CN104734352B - A kind of distribution line Loop Closing Operation control method - Google Patents

Abstract

The invention discloses a control method for loop closing operation of a power distribution line. After the main station system judges that the loop closing operation is required, the main station sends a loop closing command to a tie switch; the feeder terminal corresponding to the tie switch receives the closing command sent by the master station After the ring command, first confirm that the switch is a tie switch; then the tie switch FTU communicates with the FTUs of the two adjacent switches peer-to-peer to obtain the voltage information at the two adjacent switches, and calculate it by combining the two line voltage information that can be collected by itself. Obtain the other two line voltages at the tie switch; compare the obtained voltage information on both sides of the tie switch with the loop closing value to determine whether the current system meets the loop closing operation conditions and perform related operations. This method confirms the loop-closing conditions before the contact switch is closed, which can ensure the correctness of the loop-closing operation of the distribution network and prevent loop-closing misoperations when the loop-closing conditions are not met. The point-to-point peer-to-peer communication method is adopted between terminals, and the communication delay is small, which can ensure the timeliness of information transmission.

Description

A control method for loop closing operation of distribution lines

technical field

The invention relates to a control method for loop closing operation of a power distribution line.

Background technique

With the rapid development of distribution network construction, my country's distribution network has basically formed a grid structure of "closed-loop design, open-loop operation", that is, the line can be powered by multiple power sources, and the contact switch is in the position during normal operation. The systems on both sides of the switch operate separately. When load reversal or line maintenance is required, first close the contact switch to close the line, and then open the appropriate section switch, which can avoid short-term power failure of some lines and improve the reliability of power supply. The existing loop closing technology is mainly that the master station performs calculation and analysis based on the grid parameters uploaded by the power distribution terminal, and judges whether the system meets the loop closing conditions. If so, it sends a remote closing command to the feeder terminal (FTU) corresponding to the contact switch. After receiving the instruction, control the contact switch to close. However, there is a communication delay between the master station and the terminal, and the operating status of the distribution network changes rapidly. When the terminal receives the closing command sent by the master station, the operating status of the system may have changed without the ability to close the loop. Conditions, if the loop closing operation is performed according to the instructions, it may cause uncontrollable network circulation power, resulting in serious consequences such as protection actions and equipment damage. Therefore, it is necessary to check the current system operating parameters by the FTU before the control tie switch is closed, so as to judge and confirm whether the loop closing operation can be performed.

During the construction of distribution lines, the feeder switch is generally equipped with a single-phase voltage transformer (PT) on both sides to detect the AB phase voltage and BC phase voltage respectively. The PT supplies power to the FTU at the same time, and its secondary side rated voltage is 220V. Therefore, the FTU can only collect one line voltage signal on each side of the switch, and one is the AB phase voltage, and the other is the BC phase voltage. In actual operation, any feeder switch may become a tie switch, and the problem of insufficient voltage signal cannot be solved by adding PT to a certain switch.

The FTU corresponding to the tie switch needs to obtain the voltage information at other switches in order to judge whether the system meets the conditions for loop closure. Traditional power distribution automation mainly adopts point-to-multipoint communication, that is, the master station communicates with all distribution terminals, and FTUs need to be transferred through the master station to exchange information. Timeliness. The new communication method is point-to-point peer-to-peer communication, that is, the feeder terminals are connected to the same Ethernet, and information can be exchanged directly between any two terminals. The problem of long data processing delay. The peer-to-peer communication network can use optical fiber Ethernet. Existing research results have shown that the actual transmission delay will not exceed 10 ms under appropriate network traffic when using the connectionless transport layer User Datagram Protocol (UDP) to transmit data.

Chinese patent ZL201210257852.X discloses a control method for loop closing operation of the distribution network. The feeder terminal collects the voltage signal of the switch to calculate whether the loop can be closed, and uploads the judgment result to the master station of the distribution network. When the master station needs to close the loop According to the upload result of the terminal, it is decided whether to execute the closing operation. This method does not mention the link of confirming the loop closing conditions by the feeder terminal before closing, and the premise of its realization is that the terminal can collect all the voltage signals required for calculation, and it cannot adapt to only one voltage transformer on each side of the feeder switch. , It can collect the actual situation of insufficient voltage signal.

Chinese patent 201310156849.3 discloses a method, device and power distribution terminal for power distribution network closing and switching. It can not be used for power distribution lines where the terminal can collect insufficient voltage signals.

Contents of the invention

In order to solve the above problems, the present invention proposes a control method for loop closing operation of distribution lines. In this method, the feeder terminal confirms that the systems on both sides of the tie switch are in the same state before the loop closing operation, so as to avoid loop closing misoperation.

In order to achieve the above object, the present invention adopts the following technical solutions:

Each terminal on the feeder (including the terminal RTU in the station) realizes point-to-point communication through optical fiber Ethernet, and exchanges information on a peer-to-peer basis; the master station accesses the peer-to-peer network through a communication processor, and communicates with each terminal.

A control method for loop closing operation of a distribution line, comprising the following steps:

(1) The master station sends a ring closing command to the contact switch;

(2) After the FTU corresponding to the tie switch receives the loop closing instruction sent by the master station, it first judges whether the switch is a tie switch; if it is a tie switch, then proceed to step (3), otherwise it blocks the loop closure and reports to the master station;

(3) The FTU of the tie switch communicates peer-to-peer with the FTUs of the two adjacent segment switches to obtain the line voltage information at the two adjacent switches, and calculate the two line voltage information that can be collected by itself, and obtain the line voltage information at the tie switch. The other two line voltages;

(4) Comparing the collected and calculated voltage information on both sides of the contact switch with the loop closing value to determine whether the current system meets the loop closing operation conditions;

(5) If the loop closing condition is met, execute the loop closing command to control the contact switch to close, and report to the master station that the switch has been closed; otherwise, block the loop closing operation, and report the result to the master station.

In the step (3), the tie switch is marked as n, and the front and rear adjacent switches are respectively marked as n-1 and n+1, and the switch n-1 is located at the tie switch M side, and the switch n+1 is located at the tie switch N Assume that the PT on the M side of the switch is connected to the AB phase, and the PT on the N side of the switch is connected to the CB phase.

In the step (2), the condition for confirming the contact switch is that the switch is in the sub-position, and the voltage collected on both sides of the switch is greater than the voltage setting value, that is to say:

Among them, U _M·AB and U _N·CB are the line-to-line voltage amplitudes between AB phases on the M side of the tie switch and the line-to-line voltage amplitudes between the CB phases on the N side of the tie switch, and U _T is the constant voltage value.

In described step (3), utilize adjacent switch line voltage information to calculate other two line voltages at tie switch place, calculation formula is:

Among them, U _M·CB and U _N·AB are the line-to-line voltage amplitudes between the CB phases on the M side and the AB phases on the N side of the tie switch, and U _n-1·AB and U _n-1·CB are the line voltages at the switch n-1. The voltages, U _n+1·AB and U _n+1·CB are the line voltages at switch n+1.

In the step (4), the line voltage information on both sides of the contact switch is compared with the ring closing value to determine whether the ring closing condition is met, and the specific contents include:

a) The line voltage amplitudes on both sides of the tie switch meet the set value, that is:

U _min < U _L < U _max

Among them, U _L represents each line voltage at the contact switch, U _min is the lower limit value of the amplitude, and U _max is the upper limit value of the amplitude;

b) The corresponding line voltage amplitude difference on both sides of the switch is less than the set value, that is to say:

Among them, U _th is the setting value of the amplitude difference, which can generally be set to 10V;

c) The phase difference between the two line voltages collected by the tie switch satisfies the set value, that is:

in, Indicates the phase angle of the two line voltages. When the systems on both sides are running at the same time, the phase difference between the line voltage between CB phase and the line voltage between AB phase is 60 degrees; is the lower limit value of the phase angle difference; is the upper limit of the phase angle difference.

In the step (4), when the three conditions of the ring closing condition are all satisfied, it is considered that the systems on both sides are in the same state, and the contact switch is allowed to be closed, and the ring closing operation is performed; otherwise, the contact switch is prohibited from closing, and the ring closing is cancelled. operate.

In the step (4), when the line is overhauled or the load is transferred, switching operation is required, and the method of first closing the tie switch to close the system and then disconnecting the section switch is adopted.

The beneficial effects of the present invention are:

(1) The method of first closing the contact switch to make the system close, and then disconnecting the section switch can avoid the short-term power outage problem of some users caused by switch switching, thereby improving the reliability of power supply;

(2) The loop closing operation control method proposed by the present invention judges whether the systems on both sides are in the same period before closing the loop, and then performs the loop closing operation after confirming the synchronization, which can effectively avoid loop closing misoperations;

(3) The feeder terminal is connected to the peer-to-peer communication network, and each terminal can realize point-to-point communication through the peer-to-peer communication network without relaying through the main station, and the communication delay is small, which ensures the timeliness of information transmission.

Description of drawings

Fig. 1 is the flow chart of the control method for loop closing of distribution network of the present invention;

Figure 2 is a schematic structural diagram of a typical "hand in hand" ring overhead line;

Figure 3 is a schematic diagram of the voltage signal measured at the feeder terminal.

Among them, PT is a single-phase voltage transformer, FTU is the terminal corresponding to the feeder switch, CB1 and CB2 are outlet switches, S1-S7 is the feeder switch, among which S4 is the tie switch, FTU1-FTU7 are the feeder terminals corresponding to each feeder switch , RTU1 and RTU2 are the in-station terminals corresponding to the outlet switches, and each FTU and RTU are connected to the peer-to-peer communication network.

detailed description:

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 2, the feeder terminals are arranged in a distributed manner, and each feeder terminal is used for the measurement and control of its own switch, and each feeder terminal (including the terminal RTU in the station) is connected to the peer-to-peer communication network for point-to-point exchange of real-time information; the main station Access to the peer-to-peer network through the communication processor can communicate with any terminal. The structure of the distribution network is "closed-loop design, open-loop operation". Taking the "hand in hand" ring network powered by double-ended power supply as an example, any feeder switch can be used as a tie switch according to different operating conditions. In Figure 2, the S4 switch corresponding to FTU4 is a contact switch, and S4 is in the sub-position during normal operation, and the system operates in an open loop.

When switching operations are required for line maintenance or load transfer, the method of closing the contact switch first and then disconnecting the section switch can avoid short-term power outages for some users caused by switch switching. For example, if the transformer of substation M is overloaded, it is planned to transfer the downstream load of switch S2 from substation N. If the switch S2 is turned off first and then the tie switch S4 is turned on, it will cause a short-term power outage for users between S2 and S4; the tie switch S4 should be turned on first to close the line, and then turn off S2 to achieve power transfer. There will be no power outages for users, which improves the reliability of power supply.

The operating status of the distribution network changes rapidly. Due to the communication delay between the master station and the terminal, when the terminal receives the closing command, the operating status of the system may have changed and does not meet the conditions for closing the loop. Even one side of the line It may have been tripped due to a fault, and there may be serious consequences if the ring closing operation is performed. The present invention proposes that before performing the loop closing operation, the terminal corresponding to the contact switch judges the operating status of the systems on both sides to confirm whether the system meets the loop closing conditions.

As shown in Figure 3, a single-phase potential transformer (PT) is generally installed on both sides of the switch on site to detect the AB phase voltage and BC phase voltage respectively. Therefore, the terminal FTU4 in Figure 2 can only obtain the line-to-line voltage U _M·AB between the AB phases on the M side of the substation and the line-to-line voltage U _N·BC between the BC phases on the N side of the substation. The invention proposes that the terminal corresponding to the tie switch communicates with the feeder terminals of the two adjacent switches at the front and rear through the peer-to-peer communication network, obtains the voltage information at the adjacent switches on both sides, and makes a judgment in combination with its own voltage information. As shown in Figure 2, FTU4 communicates with FTU3 and FTU5 through a peer-to-peer network to obtain the voltage information at switches S3 and S5, where the voltage information at S3 is the line voltage U _M·AB and U _M·BC on the M side of the substation, and the voltage information at S5 The voltage information is the N-side line voltage U _N·AB and U _N·BC of the substation.

As shown in Figure 1, it is the main steps included in the distribution network loop closing control method proposed by the present invention, and the main steps are explained as follows in conjunction with Figure 2:

After the dispatcher or the main station system determines that the loop closing operation is required, the main station sends a loop closing command to the feeder terminal FTU4 corresponding to the tie switch S4, and the loop closing command is a remote closing command containing a loop closing sign;

After FTU4 receives and receives the ring closing command, first confirm whether the corresponding switch is a tie switch; if it is a tie switch, continue to perform step (3), otherwise block the ring and report to the master station; the condition for confirming the tie switch is that the switch is in the position, And the voltage collected on both sides of the switch is greater than the voltage setting value, that is, the

Among them, U _M·AB and U _N·CB are the line-to-line voltage amplitudes between AB phases on the M side of the tie switch and the phase-to-line voltage amplitudes between CB phases on the N side of the tie switch, and U _T is a fixed voltage value, which can generally be set to 0.7 times the rated voltage;

FTU4 directly communicates point-to-point with FTU3 and FTU5, obtains the voltage information at the two adjacent switches S3 and S5, and calculates the two line voltage information that can be collected by itself, and obtains the other two line voltages at the tie switch S4; the calculation formula is :

Among them, U _M·CB and U _N·AB are the line-to-line voltage amplitudes between the CB phases on the M side and the AB phases on the N side of the tie switch respectively, U _S3·AB and U _S3·CB are the line-to-line voltages at the switch S3, and U _S5·AB and U _S5·CB is the line voltage at switch S5.

Compare the voltage information on both sides of the contact switch S4 with the loop closing value to determine whether the current system has the conditions for loop closing operation; the criteria include: the line voltage amplitudes on both sides of S4 meet the set value, and the corresponding line on both sides of S4 The voltage amplitude difference is less than the set value, and the phase difference between the two line voltages collected by S4 satisfies the set value; when the above three conditions are met, the system is considered to be in the same state and meets the loop closure conditions;

The specific contents of the three conditions include:

1) The line voltage amplitudes on both sides of the tie switch meet the set value, that is:

U _min < U _L < U _max

Among them, U _L represents each line voltage at the contact switch, U _min is the lower limit value of the amplitude, which can generally be set to 0.9 times the rated voltage, and U _max is the upper limit value of the amplitude, which can generally be set to 1.1 times the rated voltage;

2) The corresponding line voltage amplitude difference on both sides of the switch is less than the set value, that is to say:

Among them, U _th is the setting value of the amplitude difference, which can generally be set to 10V;

3) The phase difference between the two line voltages collected by the tie switch satisfies the set value, that is:

in, Indicates the phase angle of the two line voltages. When the systems on both sides are running at the same time, the phase difference between the line voltage between CB phase and the line voltage between AB phase is 60 degrees; It is the lower limit value of the phase angle difference, which can generally be set to 50 degrees; It is the upper limit value of the phase angle difference, which can generally be set to 70 degrees.

If the loop-closing condition is met, execute the loop-closing instruction to control the tie switch to close, and report to the master station that the switch has been closed; otherwise, block the loop-closing operation, and report the result to the master station.

When other feeder switches operate as a tie switch, it is similar to the case where S4 is a tie switch, and details will not be repeated here. For the same reason, the method proposed by the present invention is also applicable to other forms of ring network, including but not limited to multi-segment multi-connection network, single-ring cable network, double-ring cable network, multi-supply and one-backup and other grid structures.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (6)

1. A control method for loop closing operation of distribution lines, characterized in that: comprising the following steps: (1) The master station sends a ring closing command to the contact switch; (2) After the FTU corresponding to the tie switch receives the loop closing instruction sent by the master station, it first judges whether the switch is a tie switch; if it is a tie switch, then proceed to step (3), otherwise it blocks the loop closure and reports to the master station; (3) The FTU of the tie switch communicates with the FTUs of the two adjacent switches peer-to-peer to obtain the line voltage information at the two adjacent switches, and calculate the two line voltage information that can be collected by itself, and obtain the other two lines at the tie switch. The calculation formula of using the adjacent switch line voltage information to calculate the other two line voltages at the tie switch is: ${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; B</span>}}\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; B</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; B</span>}}}$ ${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; B</span>}}\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; B</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; B</span>}}}$ Among them, U _M·CB and U _N·CB are the line-to-line voltage amplitudes between CB phases on the M side and N side CB phases of the tie switch, respectively, where U _M·AB and U _N·AB are the AB phases on the M side of the tie switch and the N side The line-to-line voltage amplitude between phases AB, U _{n-1 AB} and U _{n-1 CB} are the line voltages at switch n-1, U _{n+1 AB} and U _{n+1 CB} are the line voltages at switch n+1 line voltage; (4) Comparing the collected and calculated voltage information on both sides of the contact switch with the loop closing value to determine whether the current system meets the loop closing operation conditions; (5) If the loop closing condition is met, execute the loop closing command to control the contact switch to close, and report to the master station that the switch has been closed; otherwise, block the loop closing operation, and report the result to the master station. 2. A kind of distribution line closing operation control method as claimed in claim 1, is characterized in that: in described step (3), tie switch is denoted as n, two adjacent switches before and after are denoted as n-1 respectively and n+1, and the switch n-1 is located on the M side of the tie switch, and the switch n+1 is located on the N side of the tie switch. It is assumed that the PT on the M side of the switch is connected to the AB phase, and the PT on the N side is connected to the CB phase. 3. A kind of distribution circuit closing operation control method as claimed in claim 1, it is characterized in that: in described step (2), the condition of confirming contact switch is that this switch is in position, and switch both sides collects The voltages are all greater than the fixed value, that is to say: $\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}\end{array}\right.$ Among them, U _M·AB and U _N·CB are the line-to-line voltage amplitudes between AB phases on the M side of the tie switch and the line-to-line voltage amplitudes between the CB phases on the N side of the tie switch, and U _T is the constant voltage value. 4. A kind of control method for loop closing operation of distribution lines as claimed in claim 1, characterized in that: in said step (4), the line voltage information on both sides of the tie switch is compared with the loop closing fixed value, and it is judged whether there is loop closing conditions, including: a) The line voltage amplitudes on both sides of the tie switch meet the set value, that is: U _min < U _L < U _max Among them, U _L represents each line voltage at the contact switch, U _min is the lower limit value of the amplitude, and U _max is the upper limit value of the amplitude; b) The corresponding line voltage amplitude difference on both sides of the switch is less than the set value, that is to say: Among them, U _th is the set value of the amplitude difference, which is set to 10V; c) The phase difference between the two line voltages collected by the tie switch satisfies the set value, that is: in, Indicates the phase angle of the two line voltages. When the systems on both sides operate at the same time, the phase difference between the line voltage between CB phase and the line voltage between AB phase is 60 degrees; is the lower limit value of the phase angle difference; is the upper limit of the phase angle difference. 5. A control method for loop closure operation of distribution lines as claimed in claim 4, characterized in that: in said step (4), when the three conditions of loop closure conditions are all satisfied, it is considered that the systems on both sides are in the same period state, the contact switch is allowed to close, and the loop closing operation is performed; otherwise, the contact switch is prohibited from closing, and the loop closing operation is cancelled. 6. A control method for loop closing operation of distribution lines as claimed in claim 5, characterized in that: in said step (4), when the line is overhauled or the load is transferred, switching operation is required, and the first closing operation is adopted. The tie switch closes the system and then disconnects the section switch.