CN113917279A - Distinguishing method and system for fault phase of distribution network, method and system for judging fault line - Google Patents

Abstract

The invention discloses a method and system for judging fault phases of a distribution network, and a method and system for judging fault lines. The invention extracts three-phase current fault components when a single-phase grounding fault occurs, and extracts three-phase current energy by calculating three-phase current energy and extracting fault components. The differential and braking components are used to determine the ground fault phase. Since the transient phase current fault component is used, only the information of the initial stage of the fault is required, and it is not affected by the neutral point grounding method and the selection time of the steady-state value, and the speed can be determined. Fast and accurate.

Description

Distinguishing method and system for fault phase in distribution network, method and system for judging fault line

technical field

The invention relates to a method and system for judging fault phases of a distribution network, a method and system for judging fault lines, and belongs to the technical field of distribution automation.

Background technique

At present, the fault phase discrimination methods of distribution network are mainly divided into two types according to different electrical quantity information: one is the fault phase discrimination method based on the steady state information of the faulted phase voltage; the other is the faulted phase discrimination method based on the transient quantity of the faulted phase current. Discrimination method; among them, the first method is affected by the neutral point grounding method and the selection time of the steady-state quantity; the second method requires too much calculation, the discrimination speed is slow, and there is a risk of "misjudgment" or "missing judgment". It is rarely used in practical engineering; therefore, a new method for discriminating fault phases in distribution network is urgently needed.

SUMMARY OF THE INVENTION

The present invention provides a method, system, storage medium and computing device for determining a fault phase of a distribution network, and solves the problems disclosed in the background art.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

Discrimination methods for fault phases in distribution network, including:

In response to determining that the single-phase ground fault occurs, determining the moment of occurrence of the single-phase ground fault;

Taking the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point as the ending time, obtain the three-phase current fault component on the low-voltage side of the bus transformer between the starting time and the ending time;

According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component;

According to the three-phase current energy, the three-phase differential component, the three-phase braking component and the first preset rule, the ground fault phase is discriminated.

The method also includes the step of judging whether a single-phase-to-ground fault occurs, and the step includes:

Calculate the three-phase current variation according to the sampled three-phase current on the low-voltage side of the bus transformer;

If the variation of any phase current is greater than the threshold, it is determined that a single-phase ground fault has occurred.

In response to judging that the single-phase-to-ground fault occurs, determining the moment when the single-phase-to-ground fault occurs, including:

In response to judging that a single-phase grounding fault occurs, obtain the three-phase current variation within a preset time window before and after time _t0 ; wherein, time _t0 is the moment when it is judged that a single-phase grounding fault occurs;

Sort the acquired three-phase current variation, and filter out the phase with the largest effective value;

According to the current variation of the phase with the largest effective value and the second preset rule, the occurrence time of the single-phase ground fault is determined.

The second preset rule is:

If the sampling point n satisfies |ΔI _max,n+m |>K _s |ΔI _max,n |, then the time corresponding to the sampling point is the occurrence moment of the single-phase grounding fault;

Among them, K _s is the rate of change of singular value, ΔI _max,n+m is the maximum RMS phase current change corresponding to sampling point n+m, and m is the time required to determine that the time corresponding to sampling point n is the moment when the single-phase ground fault occurs. The number of continuous change points, ΔI _max,n is the RMS maximum phase sampling current change corresponding to the sampling point n.

The formula for calculating the three-phase current energy is:

为采样点x对应的A相电流变化量归一化值，

为采样点x对应的B相电流变化量归一化值，

为采样点x对应的C相电流变化量归一化值。Among them, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the cut-off time, n≤ x≤n+Δn,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

It is the normalized value of the C-phase current change corresponding to the sampling point x.

The formula for extracting the three-phase differential component and the three-phase braking component in the three-phase current fault component is:

为采样点x对应的A相电流变化量归一化值，

为采样点x对应的B相电流变化量归一化值，

为采样点x对应的C相电流变化量归一化值；Among them, i _da is the phase A differential component, i _db is the phase B differential component, id _dc is the phase C differential component, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the end time, n≤ x≤n+Δn,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

is the normalized value of the C-phase current change corresponding to the sampling point x;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, and i _rc is the C-phase braking component.

The first preset rule is:

E_a＞E_bk_set2、E_b≈E_c且E_a＞E_ck_set2，则A相接地故障相；like

E _a >E _b k _set2 , E _b ≈E _c and E _a >E _c k _set2 , then the A-phase ground fault phase;

E_b＞E_ak_set2、E_c≈E_a且E_b＞E_ck_set2，则B相接地故障相；like

E _b >E _a k _set2 , E _c ≈E _a and E _b >E _c k _set2 , then the B-phase ground fault phase;

E_a≈E_b、E_c＞E_ak_set2且E_c＞E_bk_set2，则C相接地故障相；like

E _a ≈E _b , E _c >E _a k _set2 and E _c >E _b k _set2 , then the C-phase ground fault phase;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient.

Distribution network fault phase discrimination system, including:

Timing determination module: in response to determining that the single-phase grounding fault occurs, determine the occurrence moment of the single-phase grounding fault;

Fault component acquisition module: take the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point is the cut-off time, to obtain the three-phase current fault component of the low-voltage side of the bus transformer between the starting time and the cut-off time;

Energy component acquisition module: According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component;

The ground fault phase discrimination module discriminates the ground fault phase according to the three-phase current energy, the three-phase differential component, the three-phase braking component and the first preset rule.

The first preset rule is:

E_a＞E_bk_set2、E_b≈E_c且E_a＞E_ck_set2，则A相接地故障相；like

E _a >E _b k _set2 , E _b ≈E _c and E _a >E _c k _set2 , then the A-phase ground fault phase;

E_b＞E_ak_set2、E_c≈E_a且E_b＞E_ck_set2，则B相接地故障相；like

E _b >E _a k _set2 , E _c ≈E _a and E _b >E _c k _set2 , then the B-phase ground fault phase;

E_a≈E_b、E_c＞E_ak_set2且E_c＞E_bk_set2，则C相接地故障相；like

E _a ≈E _b , E _c >E _a k _set2 and E _c >E _b k _set2 , then the C-phase ground fault phase;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient.

Discrimination methods for fault lines in distribution network, including:

In response to determining that the single-phase ground fault occurs, determining the moment of occurrence of the single-phase ground fault;

Taking the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point as the ending time, obtain the three-phase current fault component on the low-voltage side of the bus transformer between the starting time and the ending time;

According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component;

According to the three-phase current energy, the three-phase differential component, the three-phase braking component and the third preset rule, the ground fault line is judged.

The method also includes the step of judging whether a single-phase-to-ground fault occurs, and the step includes:

Calculate the three-phase current variation according to the sampled three-phase current on the low-voltage side of the bus transformer;

If the variation of any phase current is greater than the threshold, it is determined that a single-phase ground fault has occurred.

In response to judging that the single-phase-to-ground fault occurs, determining the moment when the single-phase-to-ground fault occurs, including:

In response to judging that a single-phase grounding fault occurs, obtain the three-phase current variation within a preset time window before and after time _t0 ; wherein, time _t0 is the moment when it is judged that a single-phase grounding fault occurs;

Sort the acquired three-phase current variation, and filter out the phase with the largest effective value;

According to the current variation of the phase with the largest effective value and the second preset rule, the occurrence time of the single-phase ground fault is determined.

The second preset rule is:

If the sampling point n satisfies |ΔI _max,n+m |>K _s |ΔI _max,n |, then the time corresponding to the sampling point is the occurrence moment of the single-phase grounding fault;

Among them, K _s is the rate of change of singular value, ΔI _max,n+m is the maximum RMS phase current change corresponding to sampling point n+m, and m is the time required to determine that the time corresponding to sampling point n is the moment when the single-phase ground fault occurs. The number of continuous change points, ΔI _max,n is the RMS maximum phase sampling current change corresponding to the sampling point n.

The formula for calculating the three-phase current energy is:

为采样点x对应的A相电流变化量归一化值，

为采样点x对应的B相电流变化量归一化值，

为采样点x对应的C相电流变化量归一化值。Among them, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the cut-off time, n≤ x≤n+Δn,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

It is the normalized value of the C-phase current change corresponding to the sampling point x.

The formula for extracting the three-phase differential component and the three-phase braking component in the three-phase current fault component is:

为采样点x对应的A相电流变化量归一化值，

为采样点x对应的B相电流变化量归一化值，

为采样点x对应的C相电流变化量归一化值；Among them, i _da is the phase A differential component, i _db is the phase B differential component, id _dc is the phase C differential component, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the end time, n≤ x≤n+Δn,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

is the normalized value of the C-phase current change corresponding to the sampling point x;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, and i _rc is the C-phase braking component.

The third preset rule is:

If the phase line meets the corresponding fault characteristics, the phase line is grounded;

If the three-phase lines meet the non-fault characteristics, the busbar is grounded;

in,

The fault characteristics are:

E_a＞E_bk_set2、

E_b≈E_c、

且E_a＞E_ck_set2；Phase A fault characteristics,

E _a >E _b k _set2 ,

E _b ≈E _c ,

and E _a >E _c k _set2 ;

E_c≈E_a、

E_b＞E_ak_set2、

且E_b＞E_ck_set2；Phase B fault characteristics,

E _c ≈E _a ,

E _b >E _a k _set2 ,

and E _b >E _c k _set2 ;

E_a≈E_b、

E_c＞E_bk_set2、

且E_c＞E_ak_set2；Phase C fault characteristics,

E _a ≈E _b ,

E _c >E _b k _set2 ,

and E _c >E _a k _set2 ;

Non-faulty characteristics are:

E_a≈E_b、

E_b≈E_c、

且E_a≈E_c；

E _a ≈E _b ,

E _b ≈E _c ,

and E _a ≈ E _c ;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient.

Distribution network fault line identification system, including:

Timing determination module: in response to determining that the single-phase grounding fault occurs, determine the occurrence moment of the single-phase grounding fault;

Fault component acquisition module: take the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point is the cut-off time, to obtain the three-phase current fault component of the low-voltage side of the bus transformer between the starting time and the cut-off time;

Energy component acquisition module: According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component;

Ground fault line identification module: According to the three-phase current energy, three-phase differential component, three-phase braking component and the third preset rule, the ground fault line is identified.

The third preset rule is:

If the phase line meets the corresponding fault characteristics, the phase line is grounded;

If the three-phase lines meet the non-fault characteristics, the busbar is grounded;

in,

The fault characteristics are:

The fault characteristics are:

E_a＞E_bk_set2、

E_b≈E_c、

且E_a＞E_ck_set2；Phase A fault characteristics,

E _a >E _b k _set2 ,

E _b ≈E _c ,

and E _a >E _c k _set2 ;

E_c≈E_a、

E_b＞E_ak_set2、

且E_b＞E_ck_set2；Phase B fault characteristics,

E _c ≈E _a ,

E _b >E _a k _set2 ,

and E _b >E _c k _set2 ;

E_a≈E_b、

E_c＞E_bk_set2、

且E_c＞E_ak_set2；Phase C fault characteristics,

E _a ≈E _b ,

E _c >E _b k _set2 ,

and E _c >E _a k _set2 ;

Non-faulty characteristics are:

E_a≈E_b、

E_b≈E_c、

且E_a≈E_c；

E _a ≈E _b ,

E _b ≈E _c ,

and E _a ≈ E _c ;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient.

A computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions that, when executed by a computing device, cause the computing device to perform a power distribution grid fault phase Identification method, or identification of fault lines in distribution network.

The beneficial effects achieved by the present invention: the present invention extracts the three-phase current fault component when a single-phase grounding fault occurs, and determines the grounding fault phase by calculating the three-phase current energy and extracting the differential and braking components in the fault component. The transient phase current fault component only needs the information of the initial stage of the fault, and is not affected by the neutral point grounding method and the selection time of the steady state quantity, and the judgment speed is fast and the accuracy is high.

Description of drawings

Figure 1 is a structural diagram of the distribution network system;

Fig. 2 is the flow chart of the method for judging the fault phase of the distribution network;

Figure 3 is a flow chart of a method for judging fault lines in a distribution network.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

As shown in Figure 1, when the system is in normal operation, the difference of the three-phase current on the low-voltage side of the bus transformer is mainly affected by the three-phase unbalance of the system, showing a non-fault characteristic; when a single-phase ground fault occurs in the system, the non-fault phase current on the low-voltage side of the bus transformer It is mainly the non-fault line capacitor current, while the fault phase current is mainly the sum of the non-fault phase capacitor currents, but the direction is opposite, and the fault phase discrimination is realized by using the difference between the fault phase and the non-fault phase.

Based on the above principles, a method for determining the fault phase of the distribution network as shown in Figure 2 is constructed, including the following steps:

Step 1, in response to judging that the single-phase grounding fault occurs, determine the moment of occurrence of the single-phase grounding fault;

Step 2, taking the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point as the ending time, obtain the three-phase current fault component of the low-voltage side of the bus transformer between the starting time and the ending time;

Step 3: Calculate the three-phase current energy according to the three-phase current fault component, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component;

Step 4, according to the three-phase current energy, the three-phase differential component, the three-phase braking component and the first preset rule, determine the ground fault phase.

The above method can be set in the detection module at the head end of the line. This method extracts the three-phase current fault component when a single-phase ground fault occurs, and determines the ground fault by calculating the three-phase current energy and extracting the differential and braking components of the fault components. Due to the use of transient phase current fault components, only the information of the initial stage of the fault is required, and it is not affected by the neutral point grounding method and the selection time of the steady-state value, and the discrimination speed is fast and the accuracy is high.

Before judging whether a single-phase ground fault occurs, first judge whether the phase current amplitude is greater than the threshold value. If not, it indicates that the phase current change may be caused by load switching, etc. If so, it can be judged according to the real-time change of the three-phase current. A single-phase-to-ground fault occurs, which can be achieved through the following steps/methods:

11) Calculate the three-phase current variation according to the sampled three-phase current on the low-voltage side of the bus transformer;

The sampled three-phase current needs to be real-time and synchronous, that is, the three-phase current of the low-voltage side of the bus transformer is sampled in real time, and the three-phase current variation is calculated. The formula is as follows:

Δi _ph (t)=i _ph (t)-i _ph (tN×ΔT)

Among them, Δi _ph (t) is the current variation of phase t at the current time (the full name is "change of phase current sampling value"), i _ph (t) is the current sampling value of phase t at the current moment, ΔT is the sampling interval time, and N is the work The number of sampling points in the frequency period.

12) If the variation of any phase current is greater than the threshold, it is determined that a single-phase grounding fault has occurred, otherwise, it is determined that there is no single-phase grounding fault, and go to 11).

If it is judged that a single-phase grounding fault occurs, the fault phase identification is officially started, and the moment of occurrence of the single-phase grounding fault can be determined by the following steps/methods:

21) Obtain the three-phase current variation in the preset time window before and after time _t0 ;

Time t ₀ is the time when the single-phase grounding fault is judged, and it is also the time when the fault phase is judged to start;

The preset time window is generally set to one cycle, that is, the three-phase current variation [Δi _ph (t ₀ )-N, Δi _ph (t ₀ )+N] in one cycle before and after time t ₀ is obtained.

22) Sort the obtained three-phase current changes in order, and screen out the phase with the largest effective value according to the sorted phase current changes; wherein, the effective value is the effective value of the sequence, that is, the sum of the squares of the three-phase current changes. root value;

The phase current changes after the ordering are as follows:

23) According to the current variation of the phase with the largest effective value and the second preset rule, determine the moment of occurrence of the single-phase ground fault;

The second preset rule is:

If the sampling point n satisfies |ΔI _max,n+m |>K _s |ΔI _max,n |, then the time corresponding to the sampling point is the occurrence moment of the single-phase grounding fault;

Among them, K _s is the rate of change of singular value, ΔI _max,n+m is the maximum RMS phase current change corresponding to sampling point n+m, and m is the time required to determine that the time corresponding to sampling point n is the moment when the single-phase ground fault occurs. The number of continuous change points, ΔI _max,n is the RMS maximum phase sampling current change corresponding to the sampling point n.

After determining that the time corresponding to the sampling point n is the occurrence moment of the single-phase grounding fault, extract the three-phase current fault component after the occurrence moment.

First, determine the next sampling positive sequence zero-crossing point n+Δn according to the occurrence time, that is, determine the cut-off time, and obtain the phase current fault component on the low-voltage side of the bus transformer between the starting time and the cut-off time. The phase current fault component is a continuous sampling The data set after value processing is transient data, which can be as follows:

Phase A: {Δi _A (n),Δi _A (n+1),Δi _A (n+2)…Δi _A (n+Δn)}

Phase B: {Δi _B (n),Δi _B (n+1),Δi _B (n+2)…Δi _B (n+Δn)}

Phase C: {Δi _C (n),Δi _C (n+1),Δi _C (n+2)…Δi _C (n+Δn)}

Normalize the acquired phase current fault components:

为采样点x对应的相电流变化量归一化值，Δi_ph(x)为采样点x对应的相电流变化量。in,

is the normalized value of the phase current variation corresponding to the sampling point x, and Δi _ph (x) is the phase current variation corresponding to the sampling point x.

Based on the normalized value, the three-phase current energy can be calculated, and the three-phase differential component and the three-phase braking component of the three-phase current fault components can be extracted. The specific formula can be:

Calculate the three-phase current energy as:

为采样点x对应的A相电流变化量归一化值，

为采样点x对应的B相电流变化量归一化值，

为采样点x对应的C相电流变化量归一化值。Among them, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the cut-off time,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

It is the normalized value of the C-phase current change corresponding to the sampling point x.

Extract the three-phase differential component and the three-phase braking component in the three-phase current fault component:

Among them, i _da is the phase A differential component, i _db is the phase B differential component, and i _dc is the phase C differential component;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, and i _rc is the C-phase braking component.

According to the three-phase current energy, the three-phase differential component, the three-phase braking component and the first preset rule, the ground fault phase is determined, wherein the first preset rule may be:

E_a＞E_bk_set2、E_b≈E_c且E_a＞E_ck_set2，则A相接地故障相；like

E _a >E _b k _set2 , E _b ≈E _c and E _a >E _c k _set2 , then the A-phase ground fault phase;

E_b＞E_ak_set2、E_c≈E_a且E_b＞E_ck_set2，则B相接地故障相；like

E _b >E _a k _set2 , E _c ≈E _a and E _b >E _c k _set2 , then the B-phase ground fault phase;

E_a≈E_b、E_c＞E_ak_set2且E_c＞E_bk_set2，则C相接地故障相；like

E _a ≈E _b , E _c >E _a k _set2 and E _c >E _b k _set2 , then the C-phase ground fault phase;

Among them, k _set1 is the reliability coefficient of the sequence component fault characteristic, and k _set2 is the phase current fault variation coefficient.

The software system corresponding to the above method, namely the distribution network fault phase discrimination system, includes:

Timing determination module: in response to determining that the single-phase ground fault occurs, determine the occurrence moment of the single-phase ground fault.

Fault component acquisition module: Take the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point is the cut-off time, to obtain the three-phase current fault components on the low-voltage side of the bus transformer between the starting time and the cut-off time.

Energy component acquisition module: According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component.

The ground fault phase discrimination module discriminates the ground fault phase according to the three-phase current energy, the three-phase differential component, the three-phase braking component and the first preset rule;

The first preset rule is:

E_a＞E_bk_set2、E_b≈E_c且E_a＞E_ck_set2，则A相接地故障相；like

E _a >E _b k _set2 , E _b ≈E _c and E _a >E _c k _set2 , then the A-phase ground fault phase;

E_b＞E_ak_set2、E_c≈E_a且E_b＞E_ck_set2，则B相接地故障相；like

E _b >E _a k _set2 , E _c ≈E _a and E _b >E _c k _set2 , then the B-phase ground fault phase;

E_a≈E_b、E_c＞E_ak_set2且E_c＞E_bk_set2，则C相接地故障相；like

E _a ≈E _b , E _c >E _a k _set2 and E _c >E _b k _set2 , then the C-phase ground fault phase;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient.

If the detection module of the above method is configured at the head end of the line, the fault line identification can be further realized, that is, the busbar grounding fault and the phase line grounding fault identification.

S1) in response to judging that the single-phase grounding fault occurs, determine the moment of occurrence of the single-phase grounding fault;

S2) Take the moment when the single-phase ground fault occurs as the starting moment, and the time corresponding to the next sampling zero-crossing point is the ending moment, and obtain the phase current fault component on the low-voltage side of the bus transformer between the starting moment and the ending moment;

S3) according to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component;

S4) According to the three-phase current energy, the three-phase differential component, the three-phase braking component and the third preset rule, determine the ground fault line.

Before judging whether a single-phase ground fault occurs, first judge whether the phase current amplitude is greater than the threshold value. If not, it indicates that the phase current change may be caused by load switching, etc. If so, it can be judged according to the real-time change of the three-phase current. A single-phase-to-ground fault occurs, which can be achieved by the following steps/methods:

11) Calculate the three-phase current variation according to the sampled three-phase current on the low-voltage side of the bus transformer;

The sampled three-phase current needs to be real-time and synchronous, that is, the three-phase current on the low-voltage side of the bus transformer is sampled in real time, and the three-phase current variation is calculated. The formula is as follows:

Δi _ph (t)=i _ph (t)-i _ph (tN×ΔT)

Among them, Δi _ph (t) is the current variation of phase t at the current time (the full name is "change of phase current sampling value"), i _ph (t) is the current sampling value of phase t at the current moment, ΔT is the sampling interval time, and N is the work The number of sampling points in the frequency period.

12) If the variation of any phase current is greater than the threshold, it is determined that a single-phase grounding fault has occurred, otherwise, it is determined that there is no single-phase grounding fault, and go to 11).

If it is judged that a single-phase grounding fault occurs, the fault phase identification is officially started, and the moment of occurrence of the single-phase grounding fault can be determined by the following steps/methods:

21) Obtain the three-phase current variation in the preset time window before and after time _t0 ;

Time t ₀ is the time when the single-phase grounding fault is judged, and it is also the time when the fault phase is judged to start;

The preset time window is generally set to one cycle, that is, the three-phase current variation [Δi _ph (t ₀ )-N, Δi _ph (t ₀ )+N] in one cycle before and after time t ₀ is obtained.

22) Sort the obtained three-phase current variation in order, and screen out the phase with the largest effective value according to the sorted phase current variation;

The phase current changes after the ordering are as follows:

23) According to the current variation of the phase with the largest effective value and the second preset rule, determine the moment of occurrence of the single-phase ground fault;

The second preset rule is:

If the sampling point n satisfies |ΔI _max,n+m |>K _s |ΔI _max,n |, then the time corresponding to the sampling point is the occurrence moment of the single-phase grounding fault;

Among them, K _s is the rate of change of singular value, ΔI _max,n+m is the maximum RMS phase current change corresponding to sampling point n+m, and m is the time required to determine that the time corresponding to sampling point n is the moment when the single-phase ground fault occurs. The number of continuous change points, ΔI _max,n is the RMS maximum phase sampling current change corresponding to the sampling point n.

After determining that the time corresponding to the sampling point n is the occurrence moment of the single-phase grounding fault, extract the three-phase current fault component after the occurrence moment.

First, determine the next sampling positive sequence zero-crossing point n+Δn according to the occurrence time, that is, determine the cut-off time, and obtain the phase current fault component of the low-voltage side of the bus transformer between the starting time and the cut-off time, which can be specifically as follows:

Phase A: {Δi _A (n),Δi _A (n+1),Δi _A (n+2)…Δi _A (n+Δn)}

Phase B: {Δi _B (n),Δi _B (n+1),Δi _B (n+2)…Δi _B (n+Δn)}

Phase C: {Δi _C (n),Δi _C (n+1),Δi _C (n+2)…Δi _C (n+Δn)}

Normalize the acquired phase current fault components:

为采样点x对应的相电流变化量归一化值，Δi_ph(x)为采样点x对应的相电流变化量。in,

is the normalized value of the phase current variation corresponding to the sampling point x, and Δi _ph (x) is the phase current variation corresponding to the sampling point x.

Based on the normalized value, the three-phase current energy can be calculated, and the three-phase differential component and the three-phase braking component of the three-phase current fault components can be extracted. The specific formula can be:

Calculate the three-phase current energy as:

为采样点x对应的A相电流变化量归一化值，

为采样点x对应的B相电流变化量归一化值，

为采样点x对应的C相电流变化量归一化值。Among them, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the cut-off time,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

It is the normalized value of the C-phase current change corresponding to the sampling point x.

Extract the three-phase differential component and the three-phase braking component in the three-phase current fault component:

Among them, i _da is the phase A differential component, i _db is the phase B differential component, and i _dc is the phase C differential component;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, and i _rc is the C-phase braking component.

According to the three-phase current energy, the three-phase differential component, the three-phase braking component and the third preset rule, the ground fault line is judged, wherein the third preset rule is:

If the phase line meets the corresponding fault characteristics, the phase line is grounded;

If the three-phase lines meet the non-fault characteristics, the busbar is grounded;

in,

The fault characteristics are:

E_a＞E_bk_set2、

E_b≈E_c、

且E_a＞E_ck_set2；Phase A fault characteristics,

E _a >E _b k _set2 ,

E _b ≈E _c ,

and E _a >E _c k _set2 ;

E_c≈E_a、

E_b＞E_ak_set2、

且E_b＞E_ck_set2；Phase B fault characteristics,

E _c ≈E _a ,

E _b >E _a k _set2 ,

and E _b >E _c k _set2 ;

E_a≈E_b、

E_c＞E_bk_set2、

且E_c＞E_ak_set2；Phase C fault characteristics,

E _a ≈E _b ,

E _c >E _b k _set2 ,

and E _c >E _a k _set2 ;

Non-fault characteristics are:

E_a≈E_b、

E_b≈E_c、

且E_a≈E_c；

E _a ≈E _b ,

E _b ≈E _c ,

and E _a ≈ E _c ;

Among them, k _set1 is the reliability coefficient of the sequence component fault characteristic, and k _set2 is the phase current fault variation coefficient.

The software system corresponding to the above method, namely the distribution network fault line discrimination system, includes:

Timing determination module: in response to determining that the single-phase ground fault occurs, determine the occurrence moment of the single-phase ground fault.

Fault component acquisition module: Take the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point is the cut-off time, to obtain the three-phase current fault components on the low-voltage side of the bus transformer between the starting time and the cut-off time.

Energy component acquisition module: According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component.

Ground fault line identification module: according to the three-phase current energy, the three-phase differential component, the three-phase braking component and the third preset rule, to determine the ground fault line;

The third preset rule is:

If the phase line meets the corresponding fault characteristics, the phase line is grounded;

If the three-phase lines meet the non-fault characteristics, the busbar is grounded;

in,

The fault characteristics are:

E_a＞E_bk_set2、

E_b≈E_c、

且E_a＞E_ck_set2；Phase A fault characteristics,

E _a >E _b k _set2 ,

E _b ≈E _c ,

and E _a >E _c k _set2 ;

E_c≈E_a、

E_b＞E_ak_set2、

且E_b＞E_ck_set2；Phase B fault characteristics,

E _c ≈E _a ,

E _b >E _a k _set2 ,

and E _b >E _c k _set2 ;

E_a≈E_b、

E_c＞E_bk_set2、

且E_c＞E_ak_set2；Phase C fault characteristics,

E _a ≈E _b ,

E _c >E _b k _set2 ,

and E _c >E _a k _set2 ;

Non-faulty characteristics are:

E_a≈E_b、

E_b≈E_c、

且E_a≈E_c；

E _a ≈E _b ,

E _b ≈E _c ,

and E _a ≈ E _c ;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient.

A computer-readable storage medium storing one or more programs, the one or more programs comprising instructions that, when executed by a computing device, cause the computing device to perform a method or distribution network fault phase discrimination method. A method for identifying faulty lines in the power grid.

A computing device comprising one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more The one or more programs are executed by a plurality of processors, and the one or more programs include instructions for executing a method of identifying a faulty phase of a distribution network or a method of identifying a faulty line of a distribution network.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

The above are only embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the pending application of the present invention. within the scope of the claims.

Claims (19)

1. A method for judging a fault phase of a distribution network, characterized in that it comprises: In response to determining that the single-phase ground fault occurs, determining the moment of occurrence of the single-phase ground fault; Taking the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point as the ending time, obtain the three-phase current fault component on the low-voltage side of the bus transformer between the starting time and the ending time; According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component; According to the three-phase current energy, the three-phase differential component, the three-phase braking component and the first preset rule, the ground fault phase is discriminated. 2 . The method for judging fault phases in a distribution network according to claim 1 , wherein the method further comprises the step of judging whether a single-phase grounding fault occurs, the step comprising: 3 . Calculate the three-phase current variation according to the sampled three-phase current on the low-voltage side of the bus transformer; If the variation of any phase current is greater than the threshold, it is determined that a single-phase ground fault has occurred. 3. The method for judging the fault phase of a distribution network according to claim 2, wherein, in response to judging that a single-phase grounding fault occurs, determining the moment when the single-phase grounding fault occurs, comprising: In response to judging that a single-phase grounding fault occurs, obtain the three-phase current variation within a preset time window before and after time _t0 ; wherein, time _t0 is the moment when it is judged that a single-phase grounding fault occurs; Sort the acquired three-phase current variation, and filter out the phase with the largest effective value; According to the current variation of the phase with the largest effective value and the second preset rule, the occurrence time of the single-phase ground fault is determined. 4. The method for judging fault phases in a distribution network according to claim 3, wherein the second preset rule is: If the sampling point n satisfies |ΔI _max,n+m |>K _s |ΔI _max,n |, then the time corresponding to the sampling point is the occurrence moment of the single-phase grounding fault; Among them, K _s is the rate of change of singular value, ΔI _max,n+m is the maximum RMS phase current change corresponding to sampling point n+m, and m is the time required to determine that the time corresponding to sampling point n is the moment when the single-phase ground fault occurs. The number of continuous change points, ΔI _max,n is the RMS maximum phase sampling current change corresponding to the sampling point n. 5. The power distribution network fault phase discrimination method according to claim 1, wherein the formula for calculating the three-phase current energy is:

Among them, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the cut-off time, n≤ x≤n+Δn,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

It is the normalized value of the C-phase current change corresponding to the sampling point x. 6. The power distribution network fault phase discrimination method according to claim 1, wherein the formula for extracting the three-phase differential component and the three-phase braking component in the three-phase current fault component is:

Among them, i _da is the phase A differential component, i _db is the phase B differential component, id _dc is the phase C differential component, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the end time, n≤ x≤n+Δn,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

is the normalized value of the C-phase current change corresponding to the sampling point x;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, and i _rc is the C-phase braking component. 7. The method for judging fault phases in a distribution network according to claim 1, wherein the first preset rule is: like

E _a >E _b k _set2 , E _b ≈E _c and E _a >E _c k _set2 , then the A-phase ground fault phase; like

E _b >E _a k _set2 , E _c ≈E _a and E _b >E _c k _set2 , then the B-phase ground fault phase; like

E _a ≈E _b , E _c >E _a k _set2 and E _c >E _b k _set2 , then the C-phase ground fault phase; Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient. 8. A system for judging fault phases of a distribution network, characterized in that it includes: Timing determination module: in response to determining that the single-phase grounding fault occurs, determine the occurrence moment of the single-phase grounding fault; Fault component acquisition module: take the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point is the cut-off time, to obtain the three-phase current fault component of the low-voltage side of the bus transformer between the starting time and the cut-off time; Energy component acquisition module: According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component; The ground fault phase discrimination module discriminates the ground fault phase according to the three-phase current energy, the three-phase differential component, the three-phase braking component and the first preset rule. 9. The distribution network fault phase discrimination system according to claim 8, wherein the first preset rule is: like

E _a >E _b k _set2 , E _b ≈E _c and E _a >E _c k _set2 , then the A-phase ground fault phase; like

E _b >E _a k _set2 , E _c ≈E _a and E _b >E _c k _set2 , then the B-phase ground fault phase; like

E _a ≈E _b , E _c >E _a k _set2 and E _c >E _b k _set2 , then the C-phase ground fault phase; Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient. 10. A method for judging fault lines in a distribution network, comprising: In response to determining that the single-phase ground fault occurs, determining the moment of occurrence of the single-phase ground fault; Taking the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point as the ending time, obtain the three-phase current fault component on the low-voltage side of the bus transformer between the starting time and the ending time; According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component; According to the three-phase current energy, the three-phase differential component, the three-phase braking component and the third preset rule, the ground fault line is judged. 11 . The method for judging fault lines in a distribution network according to claim 10 , wherein the method further comprises the step of judging whether a single-phase ground fault occurs, the step comprising: 11 . Calculate the three-phase current variation according to the sampled three-phase current on the low-voltage side of the bus transformer; If the variation of any phase current is greater than the threshold, it is determined that a single-phase ground fault has occurred. 12. The method for judging fault lines in a distribution network according to claim 11, wherein, in response to determining that a single-phase grounding fault occurs, determining the moment of occurrence of the single-phase grounding fault, comprising: In response to judging that a single-phase grounding fault occurs, obtain the three-phase current variation within a preset time window before and after time _t0 ; wherein, time _t0 is the moment when it is judged that a single-phase grounding fault occurs; Sort the acquired three-phase current variation, and filter out the phase with the largest effective value; According to the current variation of the phase with the largest effective value and the second preset rule, the occurrence time of the single-phase ground fault is determined. 13. The method for judging fault lines in a distribution network according to claim 12, wherein the second preset rule is: If the sampling point n satisfies |ΔI _max,n+m |>K _s |ΔI _max,n |, then the time corresponding to the sampling point is the occurrence moment of the single-phase grounding fault; Among them, K _s is the rate of change of singular value, ΔI _max,n+m is the maximum RMS phase current change corresponding to sampling point n+m, and m is the time required to determine that the time corresponding to sampling point n is the moment when the single-phase ground fault occurs. The number of continuous change points, ΔI _max,n is the RMS maximum phase sampling current change corresponding to the sampling point n. 14. The method for judging fault lines in a distribution network according to claim 10, wherein the formula for calculating the three-phase current energy is:

Among them, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the cut-off time, n≤ x≤n+Δn,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

It is the normalized value of the C-phase current change corresponding to the sampling point x. 15. The method for judging fault lines in a distribution network according to claim 10, wherein the formula for extracting the three-phase differential component and the three-phase braking component in the three-phase current fault component is:

Among them, i _da is the phase A differential component, i _db is the phase B differential component, id _dc is the phase C differential component, n is the sampling point corresponding to the start time, n+Δn is the sampling zero-crossing point corresponding to the end time, n≤ x≤n+Δn,

is the normalized value of the A-phase current change corresponding to the sampling point x,

is the normalized value of the B-phase current change corresponding to the sampling point x,

is the normalized value of the C-phase current change corresponding to the sampling point x;

Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, and i _rc is the C-phase braking component. 16. The method for judging fault lines in a distribution network according to claim 10, wherein the third preset rule is: If the phase line meets the corresponding fault characteristics, the phase line is grounded; If the three-phase lines meet the non-fault characteristics, the busbar is grounded; in, The fault characteristics are: Phase A fault characteristics,

E _a >E _b k _set2 ,

E _b ≈E _c ,

and E _a >E _c k _set2 ; Phase B fault characteristics,

E _c ≈E _a ,

E _b >E _a k _set2 ,

and E _b >E _c k _set2 ; Phase C fault characteristics,

E _a ≈E _b ,

E _c >E _b k _set2 ,

and E _c >E _a k _set2 ; Non-faulty characteristics are:

E _a ≈E _b ,

E _b ≈E _c ,

and E _a ≈ E _c ; Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient. 17. A system for judging fault lines in a distribution network, characterized in that it includes: Timing determination module: in response to determining that the single-phase grounding fault occurs, determine the occurrence moment of the single-phase grounding fault; Fault component acquisition module: take the time when the single-phase ground fault occurs as the starting time, and the time corresponding to the next sampling zero-crossing point is the cut-off time, to obtain the three-phase current fault component of the low-voltage side of the bus transformer between the starting time and the cut-off time; Energy component acquisition module: According to the three-phase current fault component, calculate the three-phase current energy, and extract the three-phase differential component and the three-phase braking component in the three-phase current fault component; Ground fault line identification module: According to the three-phase current energy, three-phase differential component, three-phase braking component and the third preset rule, the ground fault line is identified. 18. The distribution network fault line discrimination system according to claim 17, wherein the third preset rule is: If the phase line meets the corresponding fault characteristics, the phase line is grounded; If the three-phase lines meet the non-fault characteristics, the busbar is grounded; in, The fault characteristics are: Phase A fault characteristics,

E _a >E _b k _set2 ,

E _b ≈E _c ,

and E _a >E _c k _set2 ; Phase B fault characteristics,

E _c ≈E _a ,

E _b >E _a k _set2 ,

and E _b >E _c k _set2 ; Phase C fault characteristics,

E _a ≈E _b ,

E _c >E _b k _set2 ,

and E _c >E _a k _set2 ; Non-faulty characteristics are:

E _a ≈E _b ,

E _b ≈E _c ,

and E _a ≈ E _c ; Among them, i _ra is the A-phase braking component, i _rb is the B-phase braking component, i _rc is the C-phase braking component, i _da is the A-phase differential component, i _db is the B-phase differential component, and i _dc is the C-phase differential component Dynamic component, E _A is the current energy of phase A, E _B is the current energy of phase B, E _C is the current energy of phase C, k _set1 is the reliability coefficient of sequence component fault characteristics, and k _set2 is the phase current fault variation coefficient. 19. A computer-readable storage medium storing one or more programs, characterized in that the one or more programs comprise instructions that, when executed by a computing device, cause the computing device to perform according to the claims Any of the methods described in 1 to 7, or 10 to 16.

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