CN105334430B - A kind of single-phase ground fault distance measuring method and system based on electrical power distribution automatization system - Google Patents

Abstract

The invention discloses a single-phase ground fault ranging method based on a power distribution automation system. Firstly, the zero-sequence voltage and zero-sequence current at both ends of the distribution line are collected; Calculation state, when the zero-sequence current and voltage at both ends of the distribution line is detected; when it is detected that there is a three-phase current and voltage at one end of the distribution line and zero-sequence current at the other end; When there is no detection current and voltage at one end, the fault point of the distribution line is calculated according to the circuit model of the line distribution parameter; the present invention provides the applicable conditions for the application of the distribution network with respect to the location method of the single-phase ground fault point; the fault distance measurement in the three cases is single-phase The capture of zero-sequence voltage and zero-sequence current at the moment of grounding; using the principle of single-phase ground fault location based on the circuit model of distributed parameters of the line, only need to install power distribution terminals at the main line nodes and important branch nodes to collect line zero-sequence voltage, zero-sequence sequence current.

Description

A single-phase ground fault location method and system based on distribution automation system

technical field

The invention relates to the field of distribution network lines, in particular to a single-phase ground fault ranging method based on a distribution automation system.

Background technique

At present, most fault location devices applied to distribution lines are single-ended location devices based on the principle of impedance ranging. In the bilateral power supply mode, this ranging method is greatly affected by the transition resistance in principle, so it will be very difficult to ensure good and stable ranging accuracy.

The distance measurement accuracy is of great significance in the distance measurement of distribution network line faults, which directly affects the length of time for finding and troubleshooting line faults. High ranging accuracy can shorten the repair time, quickly restore power supply, and reduce economic losses.

Therefore, there is a need for a method of calculating fault points under different fault type conditions.

Contents of the invention

The object of the present invention is to provide a method for calculating fault points under different fault type conditions.

The purpose of the present invention is achieved by such technical scheme:

A kind of single-phase grounding fault ranging method based on distribution automation system provided by the present invention comprises the following steps:

S1: Collect the zero-sequence voltage and zero-sequence current at both ends of the distribution line;

S2: Judging the calculation state according to the zero-sequence voltage and zero-sequence current at both ends of the distribution line. When the calculation state meets the following conditions, search for line faults according to the following corresponding methods:

S21: When the zero-sequence current voltage at both ends of the distribution line is detected, calculate the zero-sequence voltage v _FM at one end of the line and the zero-sequence voltage v _FN at the other end according to the circuit model of distributed parameters of the line, and search for the zero-sequence voltage on the distribution line The point where the sequence voltage _vFM and _vFN are consistent is the fault point of the distribution line;

S22: When it is detected that there is three-phase current and voltage at one end of the distribution line and zero-sequence current at the other end,

Obtain the detected zero-sequence voltage v _F0 and detected zero-sequence current i _NF0 of the fault point F;

Calculate the zero-sequence current at one end of the distribution line according to the detected zero-sequence voltage v _F0 and the detected zero-sequence current i _NF0 of the fault point F of the distribution line distribution parameter circuit model to obtain the calculated zero-sequence current i _N0 ,

Comparing the calculated zero-sequence current i _N0 with the detected zero-sequence current i _NF0 , if the calculated zero-sequence current i _N0 is the same as the detected zero-sequence current i _NF0 , then the fault point F is a ground fault point;

If not the same, return to continue searching and calculating;

S23: When it is detected that there is a three-phase current and voltage at one end of the distribution line, and there is no detection current and voltage at the other end,

Calculate the positive sequence current i _NF1 and positive sequence current i _NF2 of the fault point F;

Calculate the zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 on the transition resistance Z _F ;

Judging whether the transition resistance zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 are equal, if they are equal, this point is the fault point;

If not equal, return and repeat;

S3: store and output the fault points.

Further, the following steps are also included:

When the fault phase voltage v _F of the fault point F is equal to zero, the point where the fault phase voltage v _F is equal to zero is the fault point.

Further, the following steps are also included:

The grounding transition resistance Z _F is calculated by obtaining the fault phase voltage v _F and the transition resistance zero sequence current i _F0 flowing on the grounding transition resistance Z _F , and the nature of the single-phase grounding fault is obtained by comparing the change of the grounding transition resistance Z _F .

Further, the detected zero-sequence current i _NF0 is calculated through the following steps:

According to the instantaneous phase principle of the instantaneous signal sinusoidal function representation method, the fault phase voltage v _F (t) and the zero-sequence current flowing into the M terminal are obtained by using the sinusoidal function representation method based on Hilbert transform The sine function says:

In the formula, means, ψ _vF (t) means, express, Indicates that ω takes the power frequency angular frequency; express i _NF0 as a sine function:

In the formula, are polynomial functions; since i _F0 =i _MF0 +i _NF0 , and the instantaneous phase of v _F is the same as that of i _F0 , we have:

According to the above formula, using the ψ _vF (t), value, which can be obtained by applying the least squares method coefficients of polynomial functions;

determined according to A polynomial function calculates the detected zero-sequence current i _NF0 .

Further, the collection of zero-sequence voltage and zero-sequence current at both ends of the distribution line is obtained through collection terminals arranged at both ends of the distribution line; electric lines.

The invention provides a single-phase ground fault ranging system based on a distribution automation system, including a distribution automation master station, a communication system and a distribution automation terminal;

The distribution automation terminal is set on the distribution line to collect electrical parameters at both ends of the distribution line, and the electrical parameters include zero-sequence voltage and zero-sequence current;

The distribution master station is the upper system of the distribution network automation system, which completes the monitoring and control of various online equipment in the distribution network system, and handles the faults that occur in the line;

The communication system uploads the electrical parameters of the distribution line collected by the distribution terminal to the distribution automation master station; and receives the control command downloaded from the distribution automation master station;

The distribution automation master station receives the electrical parameter information uploaded by the distribution automation terminal and calculates the distance to the fault point on the distribution line according to the line distribution parameter circuit model.

Further, the calculation of the fault point distance is carried out according to the following steps:

S1: Obtain the zero-sequence voltage and zero-sequence current at both ends of the distribution line;

S2: Judging the calculation state according to the zero-sequence voltage and zero-sequence current at both ends of the distribution line. When the calculation state meets the following conditions, search for line faults according to the following corresponding methods:

S21: When the zero-sequence current voltage at both ends of the distribution line is detected, calculate the zero-sequence voltage v _FM at one end of the line and the zero-sequence voltage v _FN at the other end according to the circuit model of distributed parameters of the line, and search for the zero-sequence voltage on the distribution line The point where the sequence voltage _vFM and _vFN are consistent is the fault point of the distribution line;

S22: When it is detected that there is three-phase current and voltage at one end of the distribution line and zero-sequence current at the other end,

Obtain the detected zero-sequence voltage v _F0 and detected zero-sequence current i _NF0 of the fault point F;

Calculate the zero-sequence current at one end of the distribution line according to the detected zero-sequence voltage v _F0 and the detected zero-sequence current i _NF0 of the fault point F of the distribution line distribution parameter circuit model to obtain the calculated zero-sequence current i _N0 ,

Comparing the calculated zero-sequence current i _N0 with the detected zero-sequence current i _NF0 , if the calculated zero-sequence current i _N0 is the same as the detected zero-sequence current i _NF0 , then the fault point F is a ground fault point;

If not the same, return to continue searching and calculating;

S23: When it is detected that there is a three-phase current and voltage at one end of the distribution line, and there is no detection current and voltage at the other end,

Calculate the positive sequence current i _NF1 and positive sequence current i _NF2 of the fault point F;

Calculate the zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 on the transition resistance Z _F ;

Judging whether the transition resistance zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 are equal, if they are equal, this point is the fault point;

If not equal, return and repeat;

S3: store and output the fault points.

Further, the following steps are also included:

When the fault phase voltage v _F of the fault point F is equal to zero, the point where the fault phase voltage v _F is equal to zero is the fault point;

Calculate the grounding transition resistance Z _F by obtaining the fault phase voltage v _F and the transition resistance zero-sequence current i _F0 flowing on the grounding transition resistance Z _F , and compare the change of the grounding transition resistance Z _F to obtain the nature of the single-phase grounding fault;

The collection of zero-sequence voltage and zero-sequence current at both ends of the distribution line is obtained through collection terminals arranged at both ends of the distribution line; the collection terminal is arranged on the main distribution line of the distribution line and the preset branch distribution line .

Further, the detected zero-sequence current i _NF0 is calculated through the following steps:

According to the instantaneous phase principle of the instantaneous signal sinusoidal function representation method, the fault phase voltage v _F (t) and the zero-sequence current flowing into the M terminal are obtained by using the sinusoidal function representation method based on Hilbert transform The sine function says:

In the formula, means, ψ _vF (t) means, express, Indicates that ω takes the power frequency angular frequency; express i _NF0 as a sine function:

In the formula, are polynomial functions; since i _F0 =i _MF0 +i _NF0 , and the instantaneous phase of v _F is the same as that of i _F0 , we have:

According to the above formula, using the ψ _vF (t), value, which can be obtained by applying the least squares method coefficients of polynomial functions;

determined according to A polynomial function calculates the detected zero-sequence current i _NF0 .

Owing to adopting above-mentioned technical scheme, the present invention has following advantage:

The present invention adopts the theoretical basis of the single-phase grounding fault ranging method based on the line distribution parameter circuit model, and besides the line distribution parameter circuit model, there is also a sinusoidal function representation method of the instantaneous signal. Adaptability to various single-phase ground faults under different power grid structures, different grounding methods, and different climatic conditions; for transition resistance (not less than 2000 ohms), the single-phase ground fault point location method gives the distribution network application Applicable conditions: the fault location in three cases is the capture of zero-sequence voltage and zero-sequence current at the moment of single-phase grounding, the removal of on-site interference of the collected voltage and current signals, and the correction of the polarity of the current transformer. The second and third cases are The calculation of the sine function representation of the instantaneous signal, the calculation of the sequence component current of the line on the opposite side of the fault point, and the synchronous processing of the data collected by the two detection points in the second case.

However, the current distribution automation terminal cannot realize the collection and transmission of fault characteristic information such as single-phase grounding under different grounding systems, which leads to the problem of single-phase grounding fault location in the distribution automation system that cannot be well solved.

Using the single-phase ground fault location principle based on the line distributed parameter circuit model, it is only necessary to install power distribution terminals at the main line nodes and important branch nodes to collect line zero-sequence voltage and zero-sequence current.

Other advantages, objects and features of the present invention will be set forth in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the investigation and research below, or can be obtained from It is taught in the practice of the present invention. The objects and other advantages of the invention will be realized and attained by the following description and claims.

Description of drawings

The accompanying drawings of the present invention are described as follows.

FIG. 1 is a schematic diagram of a single-phase ground fault location method based on a distribution automation system according to the present invention.

Fig. 2 is a schematic diagram of a zero-sequence network of a line single-phase-to-ground fault in the present invention.

Detailed ways

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

Example 1

As shown in the figure, a single-phase ground fault distance measurement method based on a distribution automation system provided by this embodiment is characterized in that it includes the following steps:

S1: Collect the zero-sequence voltage and zero-sequence current at both ends of the distribution line;

S2: Judging the calculation state according to the zero-sequence voltage and zero-sequence current at both ends of the distribution line. When the calculation state meets the following conditions, search for line faults according to the following corresponding methods:

S21: When the zero-sequence current voltage at both ends of the distribution line is detected, calculate the zero-sequence voltage v _FM at one end of the line and the zero-sequence voltage v _FN at the other end according to the circuit model of distributed parameters of the line, and search for the zero-sequence voltage on the distribution line The point where the sequence voltage _vFM and _vFN are consistent is the fault point of the distribution line;

S22: When it is detected that there is three-phase current and voltage at one end of the distribution line and zero-sequence current at the other end,

Obtain the detected zero-sequence voltage v _F0 and detected zero-sequence current i _NF0 of the fault point F;

Calculate the zero-sequence current at one end of the distribution line according to the detected zero-sequence voltage v _F0 and the detected zero-sequence current i _NF0 of the fault point F of the distribution line distribution parameter circuit model to obtain the calculated zero-sequence current i _N0 ,

Comparing the calculated zero-sequence current i _N0 with the detected zero-sequence current i _NF0 , if the calculated zero-sequence current i _N0 is the same as the detected zero-sequence current i _NF0 , then the fault point F is a ground fault point;

If not the same, return to continue searching and calculating;

S23: When it is detected that there is a three-phase current and voltage at one end of the distribution line, and there is no detection current and voltage at the other end,

Calculate the positive sequence current i _NF1 and positive sequence current i _NF2 of the fault point F;

Calculate the zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 on the transition resistance Z _F ;

Judging whether the transition resistance zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 are equal, if they are equal, this point is the fault point;

If not equal, return and repeat;

S3: store and output the fault points.

Also includes the following steps:

When the fault phase voltage v _F of the fault point F is equal to zero, the point where the fault phase voltage v _F is equal to zero is the fault point.

Also includes the following steps:

The grounding transition resistance Z _F is calculated by obtaining the fault phase voltage v _F and the transition resistance zero sequence current i _F0 flowing on the grounding transition resistance Z _F , and the nature of the single-phase grounding fault is obtained by comparing the change of the grounding transition resistance Z _F .

The detected zero-sequence current i _NF0 is calculated through the following steps:

According to the instantaneous phase principle of the instantaneous signal sinusoidal function representation method, the fault phase voltage v _F (t) and the zero-sequence current flowing into the M terminal are obtained by using the sinusoidal function representation method based on Hilbert transform The sine function says:

In the formula, means, ψ _vF (t) means, express, Indicates that ω takes the power frequency angular frequency; express i _NF0 as a sine function:

In the formula, are polynomial functions; since i _F0 =i _MF0 +i _NF0 , and the instantaneous phase of v _F is the same as that of i _F0 , we have:

According to the above formula, using the ψ _vF (t), value, which can be obtained by applying the least squares method coefficients of polynomial functions;

determined according to A polynomial function calculates the detected zero-sequence current i _NF0 .

The collection of zero-sequence voltage and zero-sequence current at both ends of the distribution line is obtained through collection terminals arranged at both ends of the distribution line; the collection terminal is arranged on the main distribution line of the distribution line and the preset branch distribution line .

A single-phase ground fault ranging system based on a distribution automation system provided in this embodiment includes a distribution automation master station, a communication system, and a distribution automation terminal;

The distribution automation terminal is set on the distribution line to collect electrical parameters at both ends of the distribution line, and the electrical parameters include zero-sequence voltage and zero-sequence current;

The distribution master station is the upper system of the distribution network automation system, which completes the monitoring and control of various online equipment in the distribution network system, and handles the faults that occur in the line;

The communication system uploads the electrical parameters of the distribution line collected by the distribution terminal to the distribution automation master station; and receives the control command downloaded from the distribution automation master station;

The distribution automation master station receives the electrical parameter information uploaded by the distribution automation terminal and calculates the distance to the fault point on the distribution line according to the line distribution parameter circuit model.

The calculation of the fault point distance is carried out according to the following steps:

S1: Obtain the zero-sequence voltage and zero-sequence current at both ends of the distribution line;

S2: Judging the calculation state according to the zero-sequence voltage and zero-sequence current at both ends of the distribution line. When the calculation state meets the following conditions, search for line faults according to the following corresponding methods:

S21: When the zero-sequence current voltage at both ends of the distribution line is detected, calculate the zero-sequence voltage v _FM at one end of the line and the zero-sequence voltage v _FN at the other end according to the circuit model of distributed parameters of the line, and search for the zero-sequence voltage on the distribution line The point where the sequence voltage _vFM and _vFN are consistent is the fault point of the distribution line;

S22: When it is detected that there is three-phase current and voltage at one end of the distribution line and zero-sequence current at the other end,

Obtain the detected zero-sequence voltage v _H0 and detected zero-sequence current i _NF0 of the fault point F;

Calculate the zero-sequence current at one end of the distribution line according to the detected zero-sequence voltage v _F0 and the detected zero-sequence current i _NF0 of the fault point F of the distribution line distribution parameter circuit model to obtain the calculated zero-sequence current i _N0 ,

Comparing the calculated zero-sequence current i _N0 with the detected zero-sequence current i _NF0 , if the calculated zero-sequence current i _N0 is the same as the detected zero-sequence current i _NF0 , then the fault point F is a ground fault point;

If not the same, return to continue searching and calculating;

S23: When it is detected that there is a three-phase current and voltage at one end of the distribution line, and there is no detection current and voltage at the other end,

Calculate the positive sequence current i _NF1 and positive sequence current i _NF2 of the fault point F;

Calculate the zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 on the transition resistance Z _F ;

Judging whether the transition resistance zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 are equal, if they are equal, this point is the fault point;

If not equal, return and repeat;

S3: store and output the fault points.

Also includes the following steps:

When the fault phase voltage v _F of the fault point F is equal to zero, the point where the fault phase voltage v _F is equal to zero is the fault point;

Calculate the grounding transition resistance Z _F by obtaining the fault phase voltage v _F and the transition resistance zero-sequence current i _F0 flowing on the grounding transition resistance Z _F , and compare the change of the grounding transition resistance Z _F to obtain the nature of the single-phase grounding fault;

The collection of zero-sequence voltage and zero-sequence current at both ends of the distribution line is obtained through collection terminals arranged at both ends of the distribution line; the collection terminal is arranged on the main distribution line of the distribution line and the preset branch distribution line .

The detected zero-sequence current i _NF0 is calculated through the following steps:

According to the instantaneous phase principle of the instantaneous signal sinusoidal function representation method, the fault phase voltage v _F (t) and the zero-sequence current flowing into the M terminal are obtained by using the sinusoidal function representation method based on Hilbert transform The sine function says:

In the formula, means, ψ _vF (t) means, express, Indicates that ω takes the power frequency angular frequency; express i _NF0 as a sine function:

In the formula, are polynomial functions; since i _F0 =i _MF0 +i _NF0 , and the instantaneous phase of v _F is the same as that of i _F0 , we have:

According to the above formula, using the ψ _vF (t), value, which can be obtained by applying the least squares method coefficients of polynomial functions;

determined according to A polynomial function calculates the detected zero-sequence current i _NF0 .

Example 2

As shown in the figure, a single-phase ground fault distance measurement method based on a distribution automation system provided by this embodiment includes the following steps:

S1: Collect the zero-sequence voltage and zero-sequence current at both ends of the distribution line;

S2: Determine which of the following conditions the zero-sequence voltage and zero-sequence current detection status at both ends of the distribution line meet, and search for line faults in the following manner:

S21: When the zero-sequence current voltage at both ends of the distribution line is detected, calculate the zero-sequence voltage v _FM and v FN at any point on the line according to the line distributed parameter circuit model, and search for the zero-sequence voltage v _FM and v _FN on the distribution line The point where v _FN is consistent is the fault point of the distribution line;

S22: When it is detected that there is three-phase current and voltage at one end of the distribution line and zero-sequence current at the other end,

Obtain the detected zero-sequence voltage v _F0 and detected zero-sequence current i _NF0 of the fault point F;

Calculate the zero-sequence current at one end of the distribution line according to the detected zero-sequence voltage v _F0 and the detected zero-sequence current i _NF0 of the fault point F of the distribution line distribution parameter circuit model to obtain the calculated zero-sequence current i _N0 ,

Comparing the calculated zero-sequence current i _N0 with the detected zero-sequence current i _NF0 , if the calculated zero-sequence current i _N0 is the same as the detected zero-sequence current i _NF0 , then the fault point F is a ground fault point;

If they are not the same, return to the step to continue the search calculation.

S23: When it is detected that there is a three-phase current and voltage at one end of the distribution line, and there is no detection current and voltage at the other end,

Calculate the positive sequence current i _NF1 and positive sequence current i _NF2 of the fault point F;

Calculate the zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 on the transition resistance Z _F ;

Judging whether the transition resistance zero-sequence current i _F0 , positive-sequence current i _F1 and negative-sequence current i _F2 are equal, if they are equal, this point is the fault point;

If not equal, return and repeat;

S3: store and output the fault points.

Also includes the following steps:

When the fault phase voltage v _F of the fault point F is equal to zero, the point where the fault phase voltage v _F is equal to zero is the fault point.

Also includes the following steps:

The grounding transition resistance Z _F is calculated by obtaining the fault phase voltage v _F and the transition resistance zero sequence current i _F0 flowing on the grounding transition resistance Z _F , and the nature of the single-phase grounding fault is obtained by comparing the change of the grounding transition resistance Z _F .

The detected zero-sequence current i _NF0 is calculated through the following steps:

According to the instantaneous phase principle of the instantaneous signal sinusoidal function representation method, the sinusoidal function representation method based on the Hilbert transform is used to obtain the fault phase voltage v _F and the zero-sequence current i _MF0 flowing into the M terminal. The sinusoidal function representation:

In the formula, means, ψ _vF (t) means, express, Indicates that ω takes the power frequency angular frequency; expressing i _NF0 as a sinusoidal function, we have

In the formula, are polynomial functions; since i _F0 =i _MF0 +i _NF0 , and the instantaneous phase of v _F is the same as that of i _F0 , we have:

According to the above formula, using the ψ _vF (t), value, which can be obtained by applying the least squares method coefficients of polynomial functions;

Sure Polynomial function, then i _NF0 can be obtained.

The collection of zero-sequence voltage and zero-sequence current at both ends of the distribution line is obtained through collection terminals arranged at both ends of the distribution line; the collection terminal is arranged on the main distribution line of the distribution line and the preset branch distribution line .

Example 3

The single-phase ground fault distance measurement method based on the distribution automation system provided in this embodiment, wherein, the single-phase ground fault distance measurement principle based on the line distributed parameter circuit model is as follows:

After the line fault section is determined by the single-phase ground fault section location method, the single-phase ground fault location principle based on the line distributed parameter circuit model is described in three cases, respectively, the zero-sequence current and voltage at both ends of the line can be detected The situation, the three-phase current and voltage at one end of the line can be detected and the other end only detects the zero-sequence current, the three-phase current and voltage at one end of the line can be detected and the current and voltage at the other end cannot be detected.

1) The zero-sequence current and voltage at both ends of the line can be detected

Referring to Figure 2, from M and N at both ends of the line, the given distance x and , calculate the zero-sequence voltage v _FM and v _FN at any point of the line according to the line distribution parameter circuit model, search the line to find the point where the zero-sequence voltage v _FM and v _FN are consistent is the fault point.

2) The three-phase current and voltage at one end of the line can be detected and the other end only detects the zero-sequence current

Figure 2 is a schematic diagram of the zero-sequence network for a single-phase-to-ground fault on a line. In Figure 2, the distance between M and N at both ends of the line is , the distance between the detection point M and the fault point F is x, and Z _F is the grounding transition resistance of the fault point. Positive-sequence and negative-sequence networks for single-phase-to-earth faults can also be represented in the same way.

Given the distance x, calculate the zero-sequence voltage v _F0 of point F and the zero-sequence current i _MF0 flowing into terminal M from the zero-sequence voltage and current of terminal M according to the circuit model of line distribution parameters. Similarly, the positive-sequence and negative-sequence voltage and current of terminal M can be calculated Calculate the positive-sequence voltage v _F1 and negative-sequence voltage v _F2 of point F, and obtain the fault phase voltage v _F of point F. Since the grounding transition resistance Z _F of the fault point is purely resistive, the phase of the fault phase voltage v _F and the grounding The ground current i _F0 flowing on the transition resistance Z _F is in phase. The phase of zero-sequence current i _F0 of the transition resistance is the same as that of the zero-sequence current i _MF0 flowing into terminal M, and the transition resistance Z _F is a stable resistance. Based on these two conditions, the single-phase grounding fault point can be searched. However, in actual situations, the phases of i _F0 and i _MF0 may be inconsistent, or even have a large gap, and Z _F may not be a stable resistance, so it is necessary to find the detection zero-sequence current i _NF0 flowing into the N terminal, in order Calculate i _NF0 , introduce the instantaneous phase principle of the sinusoidal function representation method of the instantaneous signal, think that at any moment, the instantaneous phase of v _F at the fault point is the same as the instantaneous phase of v _F0 , and it has nothing to do with whether Z _F is a stable resistance or not. Applying the sine function representation method based on Hilbert transform, the sine function representation of v _F and i _MF0 can be obtained, namely:

In the formula, Φ(t)v _F , Ψ(t)v _F , Φ(t) _iMF0 , Ψ(t) _{iMF0 are} unique and known, and ω is the power frequency angular frequency. Expressing i _NF0 as a sine function, there is

In the formula, Φ(t) _iMF0 and Ψ(t) _iMF0 can be expressed by a polynomial function respectively. Since i _F0 ＝i _MF0 +i _NF0 , and the instantaneous phase of v _F is the same as that of i _F0 , we have:

According to the above formula, using the values of Φ(t)v _F , Ψ(t)v _F , Φ(t) _iMF0 , Ψ(t) _iMF0 in a period of time, the least square method can be used to obtain Φ(t) _iMF0 , The coefficients of the Ψ(t) _iMF0 polynomial function, that is, the polynomial functions of Φ(t) _iMF0 and Ψ(t) _iMF0 can be determined, and then i _NF0 can be obtained.

In the case that the zero-sequence voltage v _F0 and zero-sequence current i _NF0 of point F have been obtained, the zero-sequence current i _N0 is calculated by calculating the zero-sequence current of N terminal from point F v _F0 and i _NF0 according to the circuit distribution parameter circuit model, Comparing the calculated zero-sequence current i _N0 with the detected zero-sequence current i _NF0 , if the two are consistent, point F is the ground fault point; if they are not consistent, continue to search and calculate.

In the process of searching for the ground fault point, if the above fault point conditions are not met, the fault phase voltage v _F is equal to zero, and the point where the fault phase voltage v _F is equal to zero is the fault point.

3) The three-phase current and voltage at one end of the line can be detected and the current and voltage at the other end cannot be detected

See Figure 2, the zero-sequence current i _N0 at the N terminal cannot be measured at this time. According to the calculation method of detecting the zero-sequence current i _NF0 at point F, calculate the positive-sequence current i _NF1 and positive-sequence current i _NF2 at point F with respect to the positive-sequence and negative-sequence networks, so the zero-sequence current i _F0 of the transition resistance on the transition resistance Z _F , positive sequence current i _F1 and negative sequence current i _F2 can be obtained, and the point where i _F0 , i _F1 , and i _F2 are equal is the fault point, and the ground fault point can be searched according to this ranging condition.

After obtaining the fault phase voltage v _F and the transition resistance zero-sequence current i _F0 flowing on the grounding transition resistance Z _F , the grounding transition resistance Z _F can be obtained, and the change of Z _F can be used to analyze the nature of the single-phase grounding fault.

The theoretical basis of the single-phase ground fault location method based on the distributed parameter circuit model of the line is not only the circuit model of the distributed parameter of the line, but also the sinusoidal function representation method of the instantaneous signal. The main content of the research is the adaptability of various single-phase grounding faults under different power grid structures, different grounding methods, and different climate conditions, and the adaptability of transition resistance (not less than 2000 ohms). For single-phase grounding The fault point location method provides the applicable conditions for distribution network applications; the main difficulties in the research of fault location in the three cases are the capture of the instantaneous zero-sequence voltage and zero-sequence current of single-phase grounding, and the field interference removal of the collected voltage and current signals 1. The correction of the polarity of the current transformer. The research difficulties in the second and third cases are the calculation of the sinusoidal function representation of the instantaneous signal and the calculation of the sequence component current of the line on the opposite side of the fault point. The research difficulties in the second case are Synchronous processing of data collected by two detection points.

2. Distribution automation system and terminal layout

The overall structure of distribution automation system includes: distribution automation master station, communication system and distribution automation terminal. The distribution master station is the upper system of the distribution network automation system, which completes the monitoring and control of various online equipment in the distribution network system, and handles the faults of the line; the communication system is the information exchange between the master station and the distribution terminal system. The platform and link are the nerves of the entire distribution automation system; the distribution automation terminal collects, processes and uploads the electrical quantity of the line through sensors, and monitors the distribution equipment. However, the current distribution automation terminal cannot realize the collection and transmission of fault characteristic information such as single-phase grounding under different grounding systems, which leads to the problem of single-phase grounding fault location in the distribution automation system that cannot be well solved.

Using the single-phase ground fault location principle based on the line distributed parameter circuit model, it is only necessary to install power distribution terminals at the main line nodes and important branch nodes to collect line zero-sequence voltage and zero-sequence current.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements, without departing from the spirit and scope of the technical solution, should be included in the scope of the claims of the present invention.

Claims (9)

1. A single-phase ground fault ranging method based on distribution automation system, characterized in that: comprise the following steps: S1: Collect the zero-sequence voltage and zero-sequence current at both ends of the distribution line; S2: Judging the calculation state according to the zero-sequence voltage and zero-sequence current at both ends of the distribution line. When the calculation state meets the following conditions, search for line faults according to the following corresponding methods: S21: When the zero-sequence current voltage at both ends of the distribution line is detected, calculate the zero-sequence voltage v _FM at one end of the line and the zero-sequence voltage v _FN at the other end according to the circuit model of distributed parameters of the line, and search for the zero-sequence voltage on the distribution line The point where the sequence voltage _vFM and _vFN are consistent is the fault point of the distribution line; S22: When it is detected that there is three-phase current and voltage at one end of the distribution line and zero-sequence current at the other end, Obtain the detected zero-sequence voltage of the fault point F and detection of zero sequence current Detection of Zero Sequence Voltage at Fault Point F According to Distributed Parameter Circuit Model of Distribution Line and detection of zero sequence current Calculate the zero-sequence current at one end of the distribution line to get the calculated zero-sequence current will calculate the zero sequence current and detection of zero sequence current For comparison, calculate the zero-sequence current if the and detection of zero sequence current same, then the fault point F is the ground fault point; If not the same, return to continue searching and calculating; S23: When it is detected that there is a three-phase current and voltage at one end of the distribution line, and there is no detection current and voltage at the other end, Calculate the positive sequence current at fault point F and positive sequence current Calculate the zero-sequence current across the transition resistance Z _F positive sequence current and negative sequence current Judging the transition resistance zero sequence current positive sequence current and negative sequence current Whether they are equal, if they are equal, this point is the fault point; If not equal, return and repeat; S3: store and output the fault points. 2. the single-phase grounding fault ranging method based on distribution automation system as claimed in claim 1, is characterized in that: also comprise the following steps: When the fault phase voltage of fault point F When equal to zero, the fault phase voltage Points equal to zero are failure points. 3. the single-phase grounding fault ranging method based on distribution automation system as claimed in claim 1, is characterized in that: also comprise the following steps: Get the fault phase voltage by and the zero-sequence current of the transition resistance flowing through the grounding transition resistance Z _F Calculate the grounding transition resistance Z _F , compare the change of the grounding transition resistance Z _F , and obtain the nature of the single-phase grounding fault. 4. the single-phase ground fault ranging method based on distribution automation system as claimed in claim 1, is characterized in that: described detection zero-sequence current i _NF0 is calculated by the following steps: According to the instantaneous phase principle of the instantaneous signal sinusoidal function representation method, the fault phase voltage v _F (t) and the zero-sequence current flowing into the M terminal are obtained by using the sinusoidal function representation method based on Hilbert transform The sine function says: In the formula, means, ψ _vF (t) means, express, Indicates that ω takes the angular frequency of power frequency; Do the sine function representation: In the formula, are polynomial functions, respectively; since and Instantaneous phase and The instantaneous phases are the same, with: According to the above formula, using the ψ _vF (t), value, which can be obtained by applying the least squares method coefficients of polynomial functions; determined according to The polynomial function is calculated to detect the zero-sequence current 5. The single-phase ground fault ranging method based on distribution automation system as claimed in claim 1, characterized in that: the zero-sequence voltage and zero-sequence current collection at the two ends of the distribution line are obtained by being arranged at two ends of the distribution line The collection terminal at the terminal is obtained; the collection terminal is arranged on the main distribution line of the distribution line and the preset branch distribution line. 6. A single-phase ground fault ranging system based on a distribution automation system, characterized in that: it includes a distribution automation master station, a communication system and a distribution automation terminal; The distribution automation terminal is set on the distribution line to collect electrical parameters at both ends of the distribution line, and the electrical parameters include zero-sequence voltage and zero-sequence current; The distribution master station is the upper system of the distribution network automation system, which completes the monitoring and control of various online equipment in the distribution network system, and handles the faults that occur in the line; The communication system uploads the electrical parameters of the distribution line collected by the distribution terminal to the distribution automation master station; and receives the control command downloaded from the distribution automation master station; The distribution automation master station receives the electrical parameter information uploaded by the distribution automation terminal and calculates the distance to the fault point on the distribution line according to the line distribution parameter circuit model. 7. The single-phase ground fault ranging system based on distribution automation system as claimed in claim 6, wherein: the calculation of the fault point distance is carried out according to the following steps: S1: Obtain the zero-sequence voltage and zero-sequence current at both ends of the distribution line; S2: Judging the calculation state according to the zero-sequence voltage and zero-sequence current at both ends of the distribution line. When the calculation state meets the following conditions, search for line faults according to the following corresponding methods: S21: When the zero-sequence current voltage at both ends of the distribution line is detected, calculate the zero-sequence voltage v _FM at one end of the line and the zero-sequence voltage v _FN at the other end according to the line distributed parameter circuit model, and search for the zero-sequence voltage on the distribution line The point where the sequence voltage _vFM and _vFN are consistent is the fault point of the distribution line; S22: When it is detected that there is three-phase current and voltage at one end of the distribution line and zero-sequence current at the other end, Obtain the detected zero-sequence voltage of the fault point F and detection of zero sequence current Detection of Zero Sequence Voltage at Fault Point F According to Distributed Parameter Circuit Model of Distribution Line and detection of zero sequence current Calculate the zero-sequence current at one end of the distribution line to get the calculated zero-sequence current will calculate the zero sequence current and detection of zero sequence current For comparison, calculate the zero-sequence current if the and detection of zero sequence current same, then the fault point F is the ground fault point; If not the same, return to continue searching and calculating; S23: When it is detected that there is a three-phase current and voltage at one end of the distribution line, and there is no detection current and voltage at the other end, Calculate the positive sequence current at fault point F and positive sequence current Calculate the zero-sequence current across the transition resistance Z _F positive sequence current and negative sequence current Judging the transition resistance zero sequence current positive sequence current and negative sequence current Whether they are equal, if they are equal, this point is the fault point; If not equal, return and repeat; S3: store and output the fault points. 8. The single-phase ground fault ranging system based on distribution automation system as claimed in claim 6, characterized in that: it also includes the following steps: When the fault phase voltage of fault point F When equal to zero, the fault phase voltage The point equal to zero is the fault point; Get the fault phase voltage by and the zero-sequence current of the transition resistance flowing through the grounding transition resistance Z _F Calculate the grounding transition resistance Z _F , compare the change of the grounding transition resistance Z _F , and obtain the nature of the single-phase grounding fault; The collection of zero-sequence voltage and zero-sequence current at both ends of the distribution line is obtained through collection terminals arranged at both ends of the distribution line; the collection terminal is arranged on the main distribution line of the distribution line and the preset branch distribution line . 9. The single-phase ground fault ranging system based on power distribution automation system as claimed in claim 6, wherein: said detection zero-sequence current i _NF0 is calculated by the following steps: According to the instantaneous phase principle of the instantaneous signal sinusoidal function representation method, the fault phase voltage v _F (t) and the zero-sequence current flowing into the M terminal are obtained by using the sinusoidal function representation method based on Hilbert transform The sine function says: In the formula, means, ψ _vF (t) means, express, Indicates that ω takes the angular frequency of power frequency; Do the sine function representation: In the formula, are polynomial functions, respectively; since and Instantaneous phase and The instantaneous phases are the same, with: According to the above formula, using the ψ _vF (t), value, which can be obtained by applying the least squares method coefficients of polynomial functions; determined according to The polynomial function is calculated to detect the zero-sequence current