CN105717414A - Ground fault positioning method and device based on zero sequence mutation method and vector method - Google Patents

Abstract

A ground fault location method and device based on the zero-sequence mutation method and the vector method, including an overhead current acquisition unit, a data integration communication unit, and a host computer device; the overhead current acquisition unit is connected to the data integration communication unit through a 2.4G communication circuit; The data merging communication unit is connected with the upper computer device through the GPRS module. The present invention is based on the zero-sequence catastrophe method and the vector method of the ground fault location device, adopts the current acquisition unit with different program addresses of A, B, and C phases, and the application acquisition unit is divided into A, B, and C phase acquisition and indication units, not a three-phase program The address is consistent, so that the collected current information not only contains amplitude parameters, but also has phase angle parameters, which can improve the judgment probability of ground faults in small current grounding systems, more accurately judge faults, and improve the probability of fault judgments; application The fault judgment mechanism combining the zero-sequence catastrophe method and the vector method meets the requirements of different grounding systems.

Description

Ground fault location method and device based on zero-sequence mutation method and vector method

technical field

The invention relates to a method for locating a small current ground fault, in particular to a method for locating a ground fault based on a zero-sequence mutation method and a vector method.

Background technique

The wiring of the medium voltage distribution network is complex, with many branches, and most of the line faults are single-phase ground faults. Most of my country's medium voltage distribution network adopts the neutral point through the arc suppression coil grounding system and the neutral point ungrounded system. These two grounded distribution network systems are also called small current grounding systems. After a single-phase ground fault occurs in a low-current grounding system, no short-circuit loop will be formed, and only a small grounding current will be caused by the distributed capacitance of the system. The three-phase line voltage will continue to maintain symmetry, and the system can run live for 1-2 hours. Due to the weak ground current of the small current grounding system, it is difficult to determine the ground fault point, which is why the single-phase ground fault location of the distribution network has become a well-known problem.

The existing methods of small current fault location system are: passive transient method and active injection method.

The current data acquisition device of the existing fault location system uses the traditional electrician pure iron as the magnetic circuit induction device. Accurately determine the occurrence of line faults. The zero-sequence current cannot be synthesized in the data combination communication device, and the initial phase angle cannot be calculated, so it is difficult for the previous technical solutions to accurately capture fault information. The original technical data merging communication device does not have the fault judgment ability, but only has the communication function.

In the power system, the phase angles of A, B, and C phases differ by 120°. However, the existing technology can collect the amplitude of each phase current, but cannot effectively distinguish the phase relationship, and cannot judge the fault through the method of zero-sequence steady state. If the monitoring current exceeds a certain value, a fault will be reported, and the fault judgment is not accurate.

Passive transient current method: The principle of the transient current method is to compare the instantaneously increased current value with the set value. Whether it is a short-circuit current or a ground current, as long as it is greater than the set value within a specified time, it is a fault . This type of system usually uses a fault detection probe with a simple structure, and the detection accuracy of the probe is very low, and some are even as low as about 20%, so that the correct rate of fault judgment indication in use is less than 40%. This type of system is often low in cost, but the accuracy rate is too low. It has been recognized in the market and will gradually withdraw from the market. This type of system cannot work in the arc suppression coil grounding system due to the limitation of its principle.

Active injection method: The principle of the injection method is to increase the signal PT in the station. When a ground fault occurs, the signal PT is automatically activated to inject a 60Hz half-wave signal into all lines. The fault indicator that can receive this signal will alarm, and the last one will alarm. The interval between the indicator and the next non-alarming indicator is the fault section. Although the system of injection method can adapt to different grounding systems, this method fails in power grids with dry climate, large transition resistance and many branches. And the use of signal PT may introduce harmonics endangering the grid system. The fault location system of the injection method is expensive and increases operating costs.

Contents of the invention

Aiming at the deficiencies in the prior art above, the present invention provides a grounding fault location method based on the zero-sequence catastrophe method and the vector method that meets the requirements of different grounding systems and improves the probability of fault judgment.

The technical scheme that the present invention takes is:

A ground fault location method based on zero-sequence mutation method and vector method, comprising the following steps:

Set the PT zero-sequence voltage comparison value USET in the substation;

Read the PT zero-sequence voltage UO1 in the substation;

Determine whether the PT zero-sequence voltage UO1 in the substation is greater than the PT zero-sequence voltage comparison value USET;

If the PT zero-sequence voltage UO1 in the substation is greater than the PT zero-sequence voltage ratio value USET, send a zero-sequence current sampling command to each node, otherwise continue to read the PT zero-sequence voltage UO1 in the substation;

Obtain the zero-sequence current value IO1-IOn of n nodes;

Judging whether the zero-sequence current has been obtained;

After the zero-sequence current is obtained, judge the grounding type, otherwise continue to obtain the zero-sequence current value of the node;

Determine the grounding type as the arc suppression coil; send an overcompensation adjustment command to the arc suppression coil;

Read the zero sequence voltage UO2 of the system again;

Issue the zero-sequence current sampling command again;

Obtain the zero-sequence current IO1-IOn of n nodes;

Calculate the fault point of the fault line by the sudden change method; send a single-phase grounding alarm command to the fault line;

The grounding type is non-arc suppression coil; the line with the largest zero sequence is taken as the fault line;

Zero-sequence vector method locates the fault point;

Send a single-phase grounding alarm command to the fault line.

A ground fault location device based on zero-sequence mutation method and vector method, comprising:

An overhead current collection unit for obtaining zero-sequence current values IO1-IOn of n nodes;

Restore the waveform of the collected data, calculate the amplitude of the average current value, calculate the initial phase angle of each sampling, calculate and synthesize the data of the zero-sequence current and merge the communication unit;

It is used to set the PT zero-sequence voltage comparison value USET in the substation, and read the PT zero-sequence voltage UO1 in the substation; use the sudden change method and zero-sequence vector method to calculate the fault point of the fault line, according to the fault point and non-fault point in the system The traversal identification of the fault section is judged, and the upper computer sends a single-phase grounding alarm command to the fault line and displays it on the display.

The data merging communication unit includes a box body and a box cover, fixed lifting lugs are arranged on both sides of the box body, and the fixed lifting lugs are provided with ear holes, and the two free ends of the U-shaped snap ring are connected with the ear holes through nuts; the box The cover is connected with the box body through a hinge shaft; the cover is provided with a solar panel, and the surface of the cover is provided with a support ear; the bottom of the solar panel is provided with a connection ear; the support ear and the connection ear are provided with a connection holes; the supporting ears and the connecting ears are distributed in a triangle, the upper supporting ears are connected with the connecting ears; the lower supporting ears are connected with the connecting ears through the supporting frame.

The data merging communication unit includes: a 2.4G communication circuit for communicating with the overhead current acquisition unit; and a GPRS module for communicating with the upper computer device.

The overhead current acquisition unit includes a solar panel, the solar panel is connected to the power storage circuit; the power storage circuit and an open current transformer, a current sampling circuit, a low-power single-chip processor, and a fault indication circuit It is connected with the 2.4G communication circuit; the open current transformer is connected with the short-circuit pre-judgment circuit and the current sampling circuit; the low-power single-chip processor is connected with the short-circuit pre-judgment circuit and the current sampling circuit; The on-chip processor is connected with the fault indicating circuit and the 2.4G communication circuit.

The data merging communication unit includes an embedded processor, a voltage monitoring circuit and a power supply operation indicating circuit arranged in the box.

The data merging communication unit includes a charging management circuit, which is connected with the solar panel and the maintenance-free storage battery phase and the discharge protection circuit; the discharge protection circuit is connected with the operation switch and the voltage monitoring circuit.

The beneficial effect of the present invention relative to prior art:

The grounding fault location method based on the zero-sequence mutation method and the vector method of the present invention can improve the judgment probability of a grounding fault in a small current grounding system, is much cheaper than the active injection method, and has less interference to the system. Simultaneously, the invention takes into account the load monitoring function, which is convenient for inquiring about the load situation of the overhead line.

The present invention divides the grounding types, because different grounding types have their own unique grounding fault characteristics, and different methods are selected because of their characteristics, so that the fault will be judged more accurately, and the probability of fault judgment will be higher.

The invention adopts current acquisition units with different phases A, B, and C. The application acquisition unit is divided into A, B, and C phase acquisition and indication units. The non-three-phase program addresses are consistent, so that the collected current information not only contains amplitude parameters, but also The parameter with the phase angle is beneficial to use the sudden change method and the vector method used in the present invention, and the fault judgment is more accurate.

The fault judgment mechanism combining the zero-sequence catastrophe method and the vector method is applied to meet the requirements of different grounding systems.

Description of drawings

Fig. 1 is the system structural block diagram of the ground fault location device based on the zero-sequence catastrophe method and the vector method of the utility model;

Fig. 2 is the fault judgment flowchart of the ground fault location device based on the zero-sequence catastrophe method and the vector method of the utility model;

Fig. 3 The zero-sequence equivalent diagram of the ground fault of the neutral point ungrounded system of the ground fault location device based on the zero-sequence catastrophe method and the vector method of the utility model;

Fig. 4 The zero-sequence network diagram of the utility model based on the zero-sequence catastrophe method and the vector method after the arc-suppression coil parameters are changed;

Fig. 5 The zero-sequence network diagram before the arc-suppression coil parameters of the ground fault location device based on the zero-sequence catastrophe method and the vector method of the utility model are changed;

Figure 6 is a system block diagram of the overhead network acquisition and indication unit of the utility model ground fault location device based on the zero-sequence catastrophe method and the vector method;

Figure 7 is a system diagram of the data merging communication unit of the ground fault location device based on the zero-sequence catastrophe method and the vector method of the utility model;

Figure 8 is a schematic diagram of the front view structure of the data merging communication unit of the ground fault location device based on the zero-sequence catastrophe method and the vector method of the utility model;

Fig. 9 is a schematic diagram of the side view structure of the data merging communication unit of the ground fault location device based on the zero-sequence catastrophe method and the vector method of the utility model;

Fig. 10 is a three-dimensional structural schematic diagram of the data merging communication unit of the ground fault location device based on the zero-sequence catastrophe method and the vector method of the utility model.

Explanation of symbols of main components in the accompanying drawings:

In the picture:

1GPS antenna

22.4G antenna

3GPRS antenna

4 data merge communication controller

5 fixed lugs

6 connecting ears

7U type snap ring

8 cabinets

9 solar panels

10 support frame

11 Run the switch.

12 fuses.

13 battery

14 Support ears

15 case lids.

detailed description

The present invention is described in detail below with reference to accompanying drawing and embodiment:

The U-shaped snap ring holds the utility pole in it, and acts as a fixing device.

The support frame is removed during transportation, and the solar panel can be folded, with the smallest transportation volume.

As can be seen from Figures 1-10, a ground fault location method based on the zero-sequence catastrophe method and the vector method includes the following steps:

Set the PT zero-sequence voltage comparison value USET in the substation;

Read the PT zero-sequence voltage UO1 in the substation;

Determine whether the PT zero-sequence voltage UO1 in the substation is greater than the PT zero-sequence voltage comparison value USET;

If the PT zero-sequence voltage UO1 in the substation is greater than the PT zero-sequence voltage ratio value USET, send a zero-sequence current sampling command to each node, otherwise continue to read the PT zero-sequence voltage UO1 in the substation;

Obtain the zero-sequence current value IO1-IOn of n nodes;

Judging whether the zero-sequence current has been obtained;

After the zero-sequence current is obtained, judge the grounding type, otherwise continue to obtain the zero-sequence current value of the node;

Determine the grounding type as the arc suppression coil; send an overcompensation adjustment command to the arc suppression coil;

Read the zero sequence voltage UO2 of the system again;

Issue the zero-sequence current sampling command again;

Obtain the zero-sequence current IO1-IOn of n nodes;

Calculate the fault point of the fault line by the sudden change method; send a single-phase grounding alarm command to the fault line;

The grounding type is non-arc suppression coil; the line with the largest zero sequence is taken as the fault line;

Zero-sequence vector method locates the fault point;

Send a single-phase grounding alarm command to the fault line.

A ground fault location device based on zero-sequence mutation method and vector method, comprising:

An overhead current collection unit for obtaining zero-sequence current values IO1-IOn of n nodes;

Restore the waveform of the collected data, calculate the amplitude of the average current value, calculate the initial phase angle of each sampling, calculate and synthesize the data of the zero-sequence current and merge the communication unit;

It is used to set the PT zero-sequence voltage comparison value USET in the substation, and read the PT zero-sequence voltage UO1 in the substation; use the sudden change method and zero-sequence vector method to calculate the fault point of the fault line, according to the fault point and non-fault point in the system The traversal identification of the fault section is judged, and the upper computer sends a single-phase grounding alarm command to the fault line and displays it on the display.

The data merging communication unit includes a box body 8 and a box cover 15. Fixed lugs 5 are arranged on both sides of the box body 8. The fixed lugs 5 are provided with ear holes, and the two free ends of the U-shaped snap ring 7 pass through the nut and the ear holes. The box cover 15 is connected with the box body through a hinge shaft; the box cover 15 is provided with a solar panel 9, and the surface of the box cover 15 is provided with a support ear 14; the bottom of the solar panel 9 is provided with There are connection ears 6; the support ears 14 and the connection ears 6 are provided with connection holes; the support ears 14 and the connection ears 6 are distributed in a triangle, and the upper support ears are connected with the connection ears; the lower support ears are connected to the connection ears through the support frame 10. connect.

The data merging communication unit includes: a 2.4G communication circuit for communicating with the overhead current acquisition unit; and a GPRS module for communicating with the upper computer device.

The overhead current acquisition unit includes a solar panel, the solar panel is connected to the power storage circuit; the power storage circuit and an open current transformer, a current sampling circuit, a low-power single-chip processor, and a fault indication circuit It is connected with the 2.4G communication circuit; the open current transformer is connected with the short-circuit pre-judgment circuit and the current sampling circuit; the low-power single-chip processor is connected with the short-circuit pre-judgment circuit and the current sampling circuit; The on-chip processor is connected with the fault indicating circuit and the 2.4G communication circuit.

The data merging communication unit includes an embedded processor, a voltage monitoring circuit and a power supply operation indicating circuit arranged in the box.

The data merging communication unit includes a charging management circuit, which is connected with the solar panel and the maintenance-free storage battery phase and the discharge protection circuit; the discharge protection circuit is connected with the operation switch and the voltage monitoring circuit.

Figure 2 is a schematic diagram of the fault judgment process.

The process starts at step s201.

Then step s202, read the PT zero-sequence voltage UO1 in the substation.

In step s203, determine whether the PT zero-sequence voltage UO1 in the substation is greater than the PT zero-sequence voltage comparison value USET; if the PT zero-sequence voltage UO1 in the substation is greater than the PT zero-sequence voltage comparison value USET, go to step s204, otherwise go to step s202.

In step s204, a zero-sequence current sampling command is sent to each node.

In step s205, zero-sequence current values IO1-IOn of n nodes are acquired.

In step s206, it is judged whether the zero-sequence current has been obtained; if the zero-sequence current has been obtained, step s207 is executed; otherwise, step s205 is executed.

In step s207, the grounding type is judged, and the grounding type is an arc suppressing coil, and step s209 is executed; otherwise, step s208 is executed.

In step s209, an overcompensation adjustment command is sent to the arc suppression coil.

In step s210, the zero-sequence voltage UO2 of the system is read again.

In step s211, the zero-sequence current sampling command is issued again.

In step s212, zero-sequence currents IO1-IOn of n nodes are obtained.

In step s213, the fault point of the faulty line is calculated by the sudden change method; step s215 is executed.

In step s208, the line with the largest zero sequence is taken as the faulty line.

In step s214, the zero-sequence vector method locates the fault point.

In step s215, a single-phase grounding alarm command is sent along the fault line.

The flow ends in step s216.

Among the n nodes in Fig. 1, each node is composed of a data merging unit and an ABC collection instruction unit.

In Figures 6 and 7, dotted lines represent energy flow routes, and solid lines represent data flow routes.

The present invention is based on zero-sequence catastrophe method and vector method ground fault localization method working process as follows:

Before sampling, the data merging unit uses the GPS timing module to verify the standard time of the three sampling units, and then the A, B, and C phase acquisition and indication units use the 2.4G module to transmit data with the data merging communication unit, and each sampling collects 10 cycles of data (20ms is a cycle, and each cycle collects 16 points to form a sine wave), the data merging unit restores the waveform of the collected 160 data, and then calculates the amplitude of the average current value, and calculates the initial phase of each sampling angle, calculate and synthesize the zero-sequence current, and the data merging unit calculates whether a fault occurs according to the program operation.

The data merging unit uses the remote data transmission function of the GPRS module to transmit the load current data to the host computer, and the host computer displays it; after a fault occurs, the SOE data information is sent to the host computer. Traverse identification, judge the fault section, and display it on the display.

The overhead current acquisition unit includes: A, B, and C three-phase acquisition units. The acquisition unit is responsible for collecting current information and sending it to the data merging communication unit.

The box marked with ABC in Figure 1 is the collection indicator unit. The collection indicator unit is composed of an open-type transformer, a sampling circuit board, a power-taking circuit board, a solar charging circuit, and a fault display part. The sampling circuit board uses the AD circuit to convert the current The analog quantity is replaced by the digital quantity of the voltage, and the data collected by the single-chip microcomputer is the current data at this moment. The charging circuit is to collect the electricity induced by the transformer, and store the electricity in the energy storage element for use by the circuit board. The same goes for solar charging circuits. The fault display part is divided into LED flash display and replay indication (the red sign rotates to reveal it after avoiding the cover sign).

Send current: 2.4G module, data transmission.

The data merging communication unit includes: solar power supply system, GPRS communication, 2.4G communication, and GPS satellite timing. The merging communication unit is responsible for collecting current amplitude and phase angle information by using GPS timing, and using GPRS low-power module to complete the processing The data is reported to the host computer.

The upper computer device includes: server host, SMS group sender, 3G routing device, and upper computer software. The upper computer is responsible for collecting and merging various data of communication units, remotely adjusting various parameters, and displaying load information and fault information.

The judgment process of the zero-sequence current vector method is as follows:

Figure 3 is the zero-sequence equivalent diagram of a ground fault in a neutral point ungrounded system. The system has n outgoing lines, and a phase A ground fault occurs on the outgoing line n through resistance, and the grounding excess resistance is R. The fault point is F, and the fault line is divided into two parts, which are represented by x and y symbols respectively. Zl～Zn represent the load of line 1 to line n in turn.

Since the neutral point on the high-voltage side of the distribution transformer is not grounded, the sum of the three-phase load currents on the high-voltage side is zero, that is The current of each phase at the exit of line 1 is equal to the sum of the load current of the line and the capacitance current of the phase, that is

$\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; al</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bl</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; cl</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

again ${\stackrel{\&CenterDot;}{I}}_{01}=({\stackrel{\&CenterDot;}{I}}_{a1}+{\stackrel{\&Center\; Dot;}{I}}_{b1}+{\stackrel{\&Center\; Dot;}{I}}_{c1})/3=({\stackrel{\&Center\; Dot;}{u}}_a+{\stackrel{\&CenterDot;}{u}}_b+{\stackrel{\&CenterDot;}{u}}_c){\mathrm{j\&omega;c}}_1/3+({\stackrel{\&Center\; Dot;}{I}}_{\mathrm{al}1}+{\stackrel{\&Center\; Dot;}{I}}_{\mathrm{al}1}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{al}1})/3={\stackrel{\&Center\; Dot;}{u}}_0{\mathrm{j\&omega;c}}_{\text{1}}$

From the perspective of the power supply side, according to Kirchhoff’s current law, the zero-sequence current of the outgoing line n is the sum of all non-fault phase currents, that is

${\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Viewed from the line side, the current of each phase on the outgoing line n is

$\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; ln</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; ln</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; ln</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The zero-sequence current of outgoing line n with formula (3)

${\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Combined

$<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; all</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Where c _all is the sum of all capacitance currents to ground.

Through the above analysis, some characteristics of the single-phase ground fault of the neutral point ungrounded system are obtained:

(1) The zero-sequence equivalent network is mainly composed of the ground-to-ground distributed capacitance of the line, and the ground-to-ground capacitance current of the line constitutes the zero-sequence current of each line.

(2) Since the zero-sequence current on the line is small, the zero-sequence voltage at each point on the line is approximately equal, and the zero-sequence voltage of the entire network is approximately the same value.

(3) The zero-sequence current of the non-faulty outgoing line is proportional to the zero-sequence voltage and the ground capacitance of the line. The zero-sequence current at the exit of the faulty line is equal to the sum of the zero-sequence currents of the non-faulty lines. The direction from the busbar to the line is the positive direction of the zero-sequence current, and the zero-sequence current of the non-faulty outgoing line is the positive direction of the current. The zero-sequence current of the non-faulty outgoing line is 90° ahead of the zero-sequence voltage, and the phase of the zero-sequence current at the exit of the faulty line lags behind the zero-sequence Voltage 90°.

(4) It can also be seen from the current direction that the zero-sequence current along the fault path increases gradually, and is the largest before the fault point; the zero-sequence current after the fault point is much smaller than that before the fault point, and the zero-sequence current along the positive direction of the line is zero-sequence In the positive direction of the current, the zero-sequence current on the fault path lags the zero-sequence voltage by 90°, and the zero-sequence current on the non-fault path leads the zero-sequence voltage by 90°.

(5) The size of the ground fault resistance only affects the magnitude of zero-sequence voltage and zero-sequence current, and does not affect the phase relationship between zero-sequence voltage and zero-sequence current.

The judgment process of mutation amount method is as follows:

The sudden change method is mainly aimed at the fault location method of the neutral point through the arc suppression coil grounding system. Figure 2 and Figure 3 are the zero-sequence network diagrams before and after the arc suppression coil parameters are changed, in which point f fails.

The zero-sequence currents of the non-fault and non-fault lines in Fig. 4 and Fig. 5 are respectively:

$\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 31</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$ $\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 32</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

In Figure 4 and Figure 5, the capacitive currents of each branch on the fault line to the ground are respectively:

$\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; ab</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; fd</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; fd</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$ $\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; ab</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; fd</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;c</span>}}_{\mathrm{<span\; class="notranslate">\; fd</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

The inductance current of the arc suppressing coil in Fig. 4 and Fig. 5 is

${\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; j\&omega;L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$ ${\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; j\&omega;L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

The zero-sequence current of each monitoring point on the fault line in Fig. 4 and Fig. 5

$\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; abs</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 31</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; abe</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; abs</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; ab</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bfs</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; abe</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bfe</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bfs</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bcs</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; fds</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; fd</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$ $\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; abs</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 32</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; abe</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; abs</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; ab</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bfs</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; abe</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bfe</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bfs</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bcs</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; fds</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; fd</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 13</span>}<span\; class="notranslate">\; )</span>$

When the overcompensation degree of the arc suppression coil increases, the modulus value of the inductor current changes Variation of capacitive current modulus of each non-fault line

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}<span\; class="notranslate">\; |</span>\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}}<span\; class="notranslate">\; |</span>\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 32</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 31</span>}}<span\; class="notranslate">\; |</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span>$

The changes of the modulus value of the capacitance current to ground of each section of the line on the fault line are as follows:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; ab</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; ab</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; fd</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; fd</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; fd</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; )</span>$ $\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; abs</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; abe</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; abs</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; bfs</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; abe</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; bfe</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; bfs</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; b\; f</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; bcs</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; fds</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Delta;I</span>}}_{\mathrm{<span\; class="notranslate">\; fd</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 16</span>}<span\; class="notranslate">\; )</span>$

If the fault occurs and the fault type is metallic grounding, the zero-sequence voltage remains unchanged before and after the arc suppression coil parameter is changed, and the ground capacitance current of each line remains unchanged, that is, ΔI ₁ , ΔI ₂ , ΔI ₃ , ΔI _ab , ΔI _bc , ΔI _bf , ΔI _fd are all zero, the zero-sequence current variation ΔI _abs , ΔI _abe , ΔI _bfs , ΔI _bfe on the fault path are equal to the arc suppression coil inductance current variation ΔI _L , not the zero-sequence current variation ΔI on the fault path _bcs , ΔI _{fds are} equal to zero. From this we can get the sudden change criterion under the grounding condition: when the reactance of the arc suppressing coil changes, if the modulus value of the zero-sequence current at this point changes greatly, which is approximately equal to the change of the inductive current of the arc suppressing coil, then the detection point is at On the fault path, if the zero-sequence current modulus of the point is very small, approximately zero, it means that the point is on the non-fault path.

The ground fault judgment mechanism is as follows:

Substation PT zero-sequence voltage: There are voltage transformers monitoring the three-phase zero-sequence voltage in the substation. Once a ground fault occurs, the open delta voltage of the voltage transformer will increase. When it increases to a value greater than the set value, the substation will It is considered that there is a ground fault. At this time, the invention monitoring system issues: ground fault, and the upper computer will issue a ground sampling command to order all monitoring points in the system to perform fault sampling.

Ground fault sampling: When the data merging communication unit receives the command, it will send the standard clock frequency (satellite time synchronization and time service) to the ABC three-phase acquisition unit. After completion, the acquisition unit starts to collect the current value of the transformer at the same time (160 points), send the data of these points to the data merging communication unit to perform the "Fourier" function operation. Calculate the amplitude and phase, (for the arc suppressing coil system, this is the first input sampling), the program continues.

Grounding type judgment: Before the system is put into use or the system is put into use again after transformation, the host machine will issue a grounding type parameter. This parameter is 1, indicating that the system is an arc suppression coil system; the parameter is 2, indicating that it is an ungrounded system. This parameter is not static. It changes with whether the primary equipment of the substation uses arc-suppression coils. The original system is a non-grounded system, but after the transformation of the substation, it may be an arc-suppression coil system; so the program reserves such a flag to judge the system different types, adopt different processes and methods.

The invention can improve the probability of judging the grounding fault in the small current grounding system, the price is much cheaper than the active injection method, and has less interference to the system. Simultaneously, the invention takes into account the load monitoring function, which is convenient for inquiring about the load situation of the overhead line.

The present invention divides the grounding types into partitions, because different grounding types have their own unique grounding fault characteristics, and different methods are selected because of their characteristics, so that faults can be judged more accurately and the probability of fault judgment is improved.

The present invention adopts current collection units with different program addresses for A, B, and C phases, and the application collection units are divided into A, B, and C phase collection and indication units. The non-three-phase program addresses are consistent, so that the collected current information not only contains The parameters also have the parameters of the phase angle, which is beneficial to use the sudden change method and the vector method used in the present invention, and the fault judgment is more accurate.

Claims (7)

1. the Earth design method based on zero sequence sudden change method and vector method, it is characterised in that comprise the steps:

In setting transformer station, PT residual voltage is than logarithm value USET；

Read PT residual voltage UO1 in transformer station；

Judge in transformer station PT residual voltage UO1 whether more than PT residual voltage than logarithm value USET；

In transformer station, PT residual voltage UO1 is more than PT residual voltage than logarithm value USET, sends out zero-sequence current sample command to each node, otherwise continues to read PT residual voltage UO1 in transformer station；

Obtain n node zero-sequence current numerical value IO1-IOn；

Judge whether zero-sequence current obtains complete；

Zero-sequence current obtains complete, it is judged that earthing type, otherwise continues to obtain node zero-sequence current numerical value；

Determine that earthing type is arc suppression coil；It is transmitted across compensating regulating command to arc suppression coil；

Again read off the residual voltage UO2 of system；

Again issue zero-sequence current sample command；

Obtain n node zero-sequence current IO1-IOn；

Suddenly change and mensuration calculate faulty line trouble point；Single-phase earthing alarm command is sent out along the line to fault；

Earthing type is non-arc suppression coil；Taking the maximum circuit of zero sequence is faulty line；

Zero sequence vector method orients trouble point；

Single-phase earthing alarm command is sent out along the line to fault.

2. the earth fault positioning device based on zero sequence sudden change method and vector method, it is characterised in that including:

For obtaining the built on stilts current acquisition unit of n node zero-sequence current numerical value IO1-IOn；

The data gathered being carried out waveform reduction, calculates the amplitude of average current value, calculate the initial phase angle of sampling every time, the data calculating synthesis zero-sequence current merge communication unit；

Than logarithm value USET, PT residual voltage UO1 in transformer station is read for setting PT residual voltage in transformer station；Adopt sudden change mensuration and zero sequence vector method calculates faulty line trouble point, the traversal identification according to trouble point in system Yu non-faulting point, it is judged that fault section, send out single-phase earthing alarm command the host computer shown over the display to fault along the line.

3. the earth fault positioning device of method and the vector method of suddenling change based on zero sequence according to claim 2, it is characterized in that: described data merge communication unit and include casing and case lid, described casing both sides are provided with fixing hanger, fixing hanger is provided with earhole, and two free ends of U-shaped snap ring are connected with earhole by nut；Described case lid is connected with casing by hinge axis；Being provided with solar panel on described case lid, described case lid surface configuration has support ear；It is provided with engaging lug bottom described solar panel；Support ear and engaging lug are provided with connecting hole；Described support ear and engaging lug distribution triangular in shape, upper support ear is connected with engaging lug；Supported underneath ear is connected with engaging lug by bracing frame.

4. the earth fault positioning device of method and the vector method of suddenling change based on zero sequence according to claim 2, it is characterised in that described data merge communication unit and include: for the 2.4G communicating circuit with built on stilts current acquisition unit communications；For the GPRS module with host computer device communication.

5. the earth fault positioning device of method and the vector method of suddenling change based on zero sequence according to claim 2, it is characterised in that: described built on stilts current acquisition unit includes solar panel, and solar panel is connected with power taking accumulator；Power taking accumulator is connected with Open Type Electric Current Mutual Inductor, current sampling circuit, low-power consumption monolithic processor, failure indicating circuit and 2.4G communicating circuit；Open Type Electric Current Mutual Inductor is connected with the preposition decision circuitry of short circuit, current sampling circuit；Low-power consumption monolithic processor is connected with the preposition decision circuitry of short circuit and current sampling circuit；Low-power consumption monolithic processor is connected with failure indicating circuit and 2.4G communicating circuit.

6. the earth fault positioning device of method and the vector method of suddenling change based on zero sequence according to claim 3, it is characterised in that: described data merge flush bonding processor, electric voltage observation circuit and the power supply operation indicating circuit that communication unit includes being arranged in casing.

7. the earth fault positioning device of method and the vector method of suddenling change based on zero sequence according to claim 3; it is characterized in that: described data merge communication unit and include charge management circuit, charge management circuit and solar panel and maintenance-free battery phase and discharge protection circuit are connected；Discharge protection circuit is connected with run switch and electric voltage observation circuit.