CN108336720A - Single-phase earthing traveling-wave protection method and device and computer equipment - Google Patents

Abstract

The invention provides a single-phase ground traveling wave protection method, device and computer equipment. Among them, the method includes: when a traveling wave disturbance occurs on the line, judging whether the disturbance occurs at the non-power end of the relay in the line; when it is determined that the disturbance occurs at the non-power end of the relay, judging whether a single-phase ground fault occurs at the non-power end of the relay; When a single-phase ground fault occurs, a trip signal is issued based on the time delay set according to the ladder-type principle; if the relay sends a trip command according to the trip signal, the relay on the non-power side of the line will If the situation changes, a trip command is issued. Through the technical scheme of the present invention, the power line protection is realized in succession and quick action, and the single-phase grounding fault is quickly and selectively removed from both ends of the line, providing conditions for the rapid restoration of normal line power supply, improving the reliability of power line operation, and does not require communication Channel, with good economy and practicality.

Description

Single-phase ground traveling wave protection method and device and computer equipment

This application claims the priority of the Chinese patent application with the application number 201711367445.3 and the title of the invention "Single-phase grounding traveling wave protection method and device and computer equipment" submitted to the China Patent Office on December 18, 2017, the entire content of which is incorporated by reference incorporated in this application.

technical field

The present invention relates to the technical field of power system protection and control, in particular to a single-phase grounding traveling wave protection method, a single-phase grounding traveling wave protection device, a computer device, and a computer-readable storage medium.

Background technique

Most of the existing distribution network protection technologies adopt the traditional overcurrent protection set according to the trapezoidal principle. This technology is suitable for single-power radial multi-section branch power lines widely used in our country.

However, at present, the neutral point of my country's distribution network is mostly ungrounded or grounded through the arc suppression coil, that is, the neutral point is not effectively grounded. In this distribution system, when a single-phase-to-ground fault occurs, the magnitude of the fault current is very small, which poses a great challenge to fault detection and traditional overcurrent protection. At present, there is no fast and selective single-phase grounding protection. After a single-phase grounding fault occurs, the increase of phase voltage may cause equipment insulation breakdown and further develop into a phase-to-phase fault. Therefore, timely identification and treatment should be given.

Existing power line protection technologies include current protection, voltage protection, and distance protection based on single-ended electrical quantities, current differential protection based on double-ended electrical quantities, longitudinal direction protection, and so on. However, after a power line fault occurs, the transient traveling wave information after the fault and the power frequency steady-state electrical quantity both include fault information such as fault occurrence and fault location. The power line protection can also be constructed based on transient fault traveling wave information. The protection technology based on transient traveling wave is inherently faster than the protection technology based on power frequency steady state. Therefore, research on relay protection based on transient traveling waves can promote the development of relay protection technology.

Fault information based on transient traveling waves has been used to construct traveling wave protection, traveling wave ranging and traveling wave line selection, and some progress has been made. However, the existing protection technology based on traveling wave information also has its own shortcomings. For example, it is difficult to distinguish the traveling wave generated by faults from the traveling wave generated by system disturbances such as lightning strikes or even switching operations, and it is easy to malfunction. It cannot be used in multi-section branch power lines. Remove the fault from both ends of the faulty line.

Therefore, how to provide a single-phase grounding protection method that comprehensively utilizes traveling wave protection based on polarity comparison, and can quickly and selectively cut off from both ends of the faulty line in a neutral point non-effectively grounded system with multi-section branch power lines Single-phase ground fault has become a technical problem to be solved urgently.

Contents of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

Therefore, one aspect of the present invention is to propose a single-phase grounding traveling wave protection method.

Another aspect of the present invention is to provide a single-phase grounding traveling wave protection device.

Yet another aspect of the present invention provides a computer device.

Yet another aspect of the present invention provides a computer-readable storage medium.

In view of this, the present invention proposes a single-phase grounding traveling wave protection method, including: when a traveling wave disturbance occurs in the line, judging whether the disturbance occurs at the non-power end of the relay; when it is determined that the disturbance occurs at the non-power end of the relay, judging Whether a single-phase ground fault occurs at the non-power end of the relay; when it is determined that a single-phase ground fault occurs, a trip signal is issued based on the time set according to the ladder-type principle; if the relay sends a trip command according to the trip signal, the relay on the non-power side of the line will According to the detected changes in the three-phase power frequency electrical quantity, a trip command will be issued.

After a power line fault occurs, the power system enters a post-fault steady state after a transient process. Both the transient traveling wave information and the steady-state power frequency information after a fault are part of the fault phenomenon, and they can also reflect the fault. The transient traveling wave information reflects the microscopic situation after the AC system fails, and the steady-state power frequency The macroscopic situation of the system after the failure of the AC system is obtained. After a power line fault occurs, the system will generate a fault traveling wave that propagates along the system starting from the fault point. The initial fault traveling wave is only affected by the electrical equipment on the path it passes through, and is not affected by the electrical equipment that the traveling wave has not passed through in the system. Therefore, at the measurement point, the initial traveling wave is not affected by the way the neutral point is grounded. In addition, when we specify that the positive direction of the current traveling wave is that the bus bar points to the next line, after the protected line fails, the polarity of the initial current and voltage traveling wave detected by the relay on the power supply side is opposite, and the initial current detected by the relay on the non-power supply side The voltage traveling waves have the same polarity.

According to the single-phase grounding traveling wave protection method of the present invention, any branch line (that is, a single-ended power supply radial distribution line disconnected by a single circuit breaker) in a neutral point non-effective grounding system containing multi-section branch power lines, based on Detect the traveling wave electrical quantity at both ends of the protected line, and judge whether there is a disturbance on the protected line. If a disturbance occurs, based on the polarity comparison of the initial traveling wave, determine which side of the relay the disturbance occurs on. At the power supply end, based on the power frequency electrical quantity, it is judged whether a single-phase ground fault has occurred at the non-power end of the relay, and the fault and disturbance are distinguished. If a single-phase ground fault occurs at the non-power end of the relay, it is based on Time delay waits for action. When the relay with the shortest time delay setting trips first, the faulty line is cut off from the power supply side, and the change of the three-phase power frequency electrical quantity sensed by the relay on the opposite end without power supply is specific. The relay on the power supply side will detect that the effective value of the three-phase current approaches zero, and use this as a criterion to issue a trip command to cut off the faulty line from the non-power supply side. Through the single-phase grounding traveling wave protection method of the present invention, not only can the single-phase grounding fault be detected accurately and quickly, but also the single-phase grounding fault can be quickly and selectively cut off from both ends of the faulty line, so as to realize the power line protection of the whole line successively and quickly It provides conditions for quick restoration of normal line power supply, improves the reliability of power line operation, and does not require communication channels, which has good economy and practicability.

The traveling wave in the present invention refers to the electromagnetic wave propagating in the power system caused by the disturbance of the power equipment in operation.

In the above technical solution, preferably, the setting time is set according to the ladder-type principle, specifically: setting the corresponding setting time according to the distance between the relay and the power supply; wherein, the closer the distance is, the longer the setting time is.

In this technical solution, the closer the relay is to the power supply, the longer the corresponding setting time. If a traveling wave disturbance occurs in the system, judge which end of the relay the disturbance occurs at. If it occurs at the non-power end of the relay, when judging whether a single-phase ground fault occurs at the non-power end of the relay, if a single-phase ground fault occurs, each such The relays will act after a delay according to the corresponding setting time. When the relay with the shortest delay sends a trip command, the faulty line will be cut off from the power supply side, and the non-power side relay on the other side will use the three-phase power frequency electric current sensed According to the change of the quantity, a trip command is issued to cut off the faulty line from the non-power side. In this way, the power line protection can be activated sequentially across the entire line, accurately and quickly detect single-phase ground faults, and quickly and selectively remove single-phase ground faults from both ends of the line.

In any of the above technical solutions, preferably, the method further includes: collecting the three-phase voltage traveling wave and the three-phase current traveling wave at both ends of the line in real time; combining the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity with the Compared with the preset threshold value, if the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity is greater than the preset threshold value, it is determined that a traveling wave disturbance occurs.

In this technical scheme, the three-phase voltage traveling wave and the three-phase current traveling wave on the protected line are synchronously collected in real time according to the preset sampling frequency (such as 1Mhz); the analog quantities of the real-time three-phase voltage traveling wave or three-phase current traveling wave The input level comparison circuit is compared with the preset threshold to judge whether traveling wave disturbance occurs in the system. Wherein, the setting of the threshold may be 200mv. Specifically, when the three-phase voltage traveling wave analog quantity or the three-phase voltage traveling wave analog quantity is greater than a preset threshold, it is determined that a traveling wave disturbance occurs in the system.

Those skilled in the art should understand that the sampling frequency is 1Mhz, but not limited thereto; the preset threshold is 200mv, but not limited thereto.

In any of the above technical solutions, preferably, the step of judging whether the disturbance occurs at the non-power end of the relay includes: respectively storing the initial three-phase voltage traveling wave and the initial three-phase current traveling wave, calculating the three-phase voltage traveling wave modulus and The three-phase current traveling wave modulus; the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus are respectively subjected to four-layer wavelet transform, and the corresponding wavelet transform modulus maxima are extracted according to the respective wavelet transform results; The wavelet transform modulus maximum value of the three-phase voltage traveling wave modulus of each layer in the four layers is compared with the wavelet transform modulus maximum value of the corresponding three-phase current traveling wave modulus; if there are at least three layers of three The polarity of the wavelet transform modulus maxima of the phase voltage traveling wave modulus is opposite to the polarity of the corresponding three-phase current traveling wave modulus wavelet transform modulus maxima, so it is determined that the disturbance occurs at the non-power supply end of the relay.

In any of the above technical solutions, preferably, the three-phase voltage traveling wave modulus includes the three-phase voltage traveling wave linear mode component and/or the three-phase voltage traveling wave zero-mode component, and the three-phase current traveling wave modulus includes the three-phase electric current traveling wave modulus The linear mode component of the prevailing wave and/or the zero mode component of the three-phase current traveling wave.

In this technical solution, if a traveling wave disturbance occurs in the system, four layers of wavelet transformation are performed on the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus respectively, and the wavelet function here can choose three B samples The first-order derivative of the function. The corresponding modulus maxima are extracted according to the respective wavelet transform results. By comparing the polarity of the maximum value of the four-layer wavelet transform modulus of the voltage traveling wave modulus with the corresponding polarity of the four-layer wavelet transform modulus maximum of the current traveling wave modulus, it is judged whether the disturbance occurs at the non-power supply end of the relay.

Specifically, if a traveling wave disturbance is detected in the system, the initial three-phase voltage traveling wave and the initial three-phase current traveling wave are stored, such as 64 points of data before and after the disturbance. The phase-mode transformation is carried out on the three-phase voltage traveling wave, and the phase-mode transformation matrix adopts the Karen Bell matrix, so as to obtain the three-phase voltage traveling wave line-mode component and the three-phase voltage traveling wave zero-mode component. Similarly, the phase-mode transformation is performed on the three-phase current traveling wave, and the transformation matrix adopts the Karen Bell matrix, so as to obtain the three-phase current traveling wave line-mode component and the three-phase current traveling wave zero-mode component.

Compare the polarity of the four-level wavelet transform modulus maximum value of the voltage traveling wave linear mode component with the corresponding polarity of the four-level wavelet transform modulus maximum value of the current traveling wave line mode component, if there are no less than three layers of voltage traveling wave line mode components If the polarity of the wavelet transform modulus maxima of the corresponding current traveling wave linear mode component is opposite, it is determined that the disturbance occurs at the relay without power supply; or, compare the four-level wavelet transform modulus maxima of the voltage traveling wave zero-mode component The polarity of the wavelet transform modulus maxima of the four-layer wavelet transform of the current traveling wave zero-mode component, if there are no less than three layers of the voltage traveling wave zero-mode component and the wavelet transform modulus polarity of the current traveling wave zero-mode component are opposite, Then it is determined that the disturbance occurs at the non-power supply end of the relay; if none of the above is satisfied, it is determined that the disturbance occurs outside the protected line. Through the technical solution of the present invention, single-phase grounding faults and disturbances can be distinguished, thereby avoiding the problem in the related art that it is difficult to distinguish traveling waves generated by faults from traveling waves generated by system disturbances such as lightning strikes or even switching operations, and are prone to misoperation.

Those skilled in the art should understand that the real-time collected three-phase voltage traveling wave and three-phase current traveling wave data of 64 points before and after the disturbance are only one of the transient traveling wave data after the fault, but the transient traveling wave data after the fault Not limited to this.

In any of the above technical solutions, preferably, the step of judging whether a single-phase ground fault occurs at the non-power end of the relay includes: collecting the three-phase power frequency voltage and the three-phase power frequency current at both ends of the line in real time; storing the initial three-phase The power frequency voltage and the initial three-phase power frequency current, and the phase sequence transformation of the initial three-phase power frequency voltage and the initial three-phase power frequency current, respectively, to obtain the effective value of the power frequency zero-sequence voltage and the effective value of the three-phase power frequency current ;Compare the effective value of the power frequency zero-sequence voltage with the voltage setting value. If the effective value of the power frequency zero-sequence voltage is greater than the voltage setting value, it is determined that a ground fault occurs at the non-power end of the relay; when it is determined that a ground fault occurs at the non-power end of the relay, compare The RMS value and current setting value of the three-phase power frequency current. If the RMS value of each phase of the three-phase power frequency current is lower than the current setting value, it is determined that a single-phase ground fault has occurred at the non-power end of the relay.

After the ground fault occurs in the power line, the steady-state power frequency electrical quantity after the fault has changed significantly compared with that before the fault. Before the fault, the three phases are symmetrical, and the three-phase voltage is symmetrical and maintained near the rated voltage; the three-phase current is the load current, and there is no significant zero-sequence voltage and zero-sequence current. After a fault, the voltage and current will change significantly. In the non-effective neutral point grounding system, after a single-phase ground fault, the zero-sequence voltage increases, and the healthy phase-to-phase voltage increases, except for a short-circuit fault other than single-phase grounding, the fault phase current increases, and the fault phase voltage decreases.

In this technical solution, if a traveling wave disturbance occurs at the non-power end of the relay, the real-time collected initial three-phase power frequency voltage and initial three-phase power frequency current are stored, such as 24 points of data after the disturbance. Perform phase sequence transformation on the three-phase power frequency voltage and three-phase power frequency current to obtain the positive, negative and zero three-sequence components of the three-phase power frequency voltage, and then use the Fourier transform to obtain the effective zero-sequence voltage of the power frequency value and the effective value of the three-phase power frequency current. By comparing the effective value of the zero-sequence voltage with the voltage setting value, if the effective value of the zero-sequence voltage is greater than the voltage setting value, it is determined that a ground fault has occurred at the non-power end of the relay; If the effective value of the current is lower than the current setting value, it is determined that a single-phase ground fault has occurred at the non-power end of the relay.

Those skilled in the art should understand that the real-time collected three-phase power frequency voltage and three-phase power frequency current 24-point data after disturbance is only one of the steady-state power frequency data after the fault, but the steady-state power frequency data after the fault is not limited to this.

In any of the above technical solutions, preferably, the voltage setting value is equal to the product of the upper critical value of the zero-sequence voltage under normal system operation and the first preset coefficient; the current setting value is equal to the upper critical value of the load current under normal system operation The product of the value and the second preset coefficient.

In this technical solution, the voltage setting value is set by multiplying the maximum zero-sequence voltage amplitude that may occur under normal system operation with a reliability factor, and the current setting value is set according to the maximum load current that may occur under normal system operation and another Reliability coefficients are multiplied and set.

The present invention also proposes a single-phase grounding traveling wave protection device, including: a disturbance unit, used to determine whether the disturbance occurs at the non-power end of the relay in the line when a traveling wave disturbance occurs on the line; a fault unit, used to determine whether the disturbance occurs occurs at the non-power end of the relay, and judges whether a single-phase ground fault occurs at the non-power end of the relay; the protection unit is used to determine whether a single-phase ground fault occurs, and sends a trip signal based on the time set according to the ladder-type principle; the protection unit also If the relay sends a trip command according to the trip signal, the relay on the non-power side of the line will send a trip command according to the detected change of the three-phase power frequency electrical quantity.

According to the single-phase grounding traveling wave protection device of the present invention, any branch line in a neutral point non-effective grounding system containing multi-section branch power lines (that is, a single-ended power supply radial distribution line broken by a single circuit breaker) is based on Detect the traveling wave electrical quantity at both ends of the protected line, and judge whether there is a disturbance on the protected line. If a disturbance occurs, based on the polarity comparison of the initial traveling wave, determine which side of the relay the disturbance occurs on. At the power supply end, based on the power frequency electrical quantity, it is judged whether a single-phase ground fault has occurred at the non-power end of the relay, and the fault and disturbance are distinguished. If a single-phase ground fault occurs at the non-power end of the relay, it is based on Time delay waits for action. When the relay with the shortest time delay setting trips first, the faulty line is cut off from the power supply side, and the change of the three-phase power frequency electrical quantity sensed by the relay on the opposite end without power supply is specific. The relay on the power supply side will detect that the effective value of the three-phase current approaches zero, and use this as a criterion to issue a trip command to cut off the faulty line from the non-power supply side. Through the single-phase grounding traveling wave protection method of the present invention, not only can the single-phase grounding fault be detected accurately and quickly, but also the single-phase grounding fault can be quickly and selectively cut off from both ends of the faulty line, so as to realize the power line protection of the whole line successively and quickly It provides conditions for quick restoration of normal line power supply, improves the reliability of power line operation, and does not require communication channels, which has good economy and practicability.

In the above technical solution, preferably, the setting time is set according to the step-type principle, specifically: setting the corresponding setting time according to the distance between the relay and the power supply, wherein the closer the distance is, the longer the setting time is.

In this technical solution, the closer the relay is to the power supply, the longer the corresponding setting time. If a traveling wave disturbance occurs in the system, judge which end of the relay the disturbance occurs at. If it occurs at the non-power end of the relay, when judging whether a single-phase ground fault occurs at the non-power end of the relay, if a single-phase ground fault occurs, each such The relays will act after a delay according to the corresponding setting time. When the relay with the shortest delay sends a trip command, the faulty line will be cut off from the power supply side, and the non-power side relay on the other side will use the three-phase power frequency electric current sensed According to the change of the quantity, a trip command is issued to cut off the faulty line from the non-power side. In this way, the power line protection can be activated sequentially across the entire line, accurately and quickly detect single-phase ground faults, and quickly and selectively remove single-phase ground faults from both ends of the line.

In any of the above technical solutions, preferably, the disturbance unit is specifically used to: collect the three-phase voltage traveling wave and the three-phase current traveling wave at both ends of the line in real time; simulate the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave The quantity is compared with the preset threshold value, and if the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity is greater than the preset threshold value, it is determined that a traveling wave disturbance occurs.

In this technical scheme, the three-phase voltage traveling wave and the three-phase current traveling wave on the protected line are synchronously collected in real time according to the preset sampling frequency (such as 1Mhz); the analog quantities of the real-time three-phase voltage traveling wave or three-phase current traveling wave The input level comparison circuit is compared with the preset threshold to judge whether traveling wave disturbance occurs in the system. Wherein, the setting of the threshold may be 200mv. Specifically, when the three-phase voltage traveling wave analog quantity or the three-phase voltage traveling wave analog quantity is greater than a preset threshold, it is determined that a traveling wave disturbance occurs in the system.

Those skilled in the art should understand that the sampling frequency is 1Mhz, but not limited thereto; the preset threshold is 200mv, but not limited thereto.

In any of the above technical solutions, preferably, the disturbance unit is further specifically used to: respectively store the initial three-phase voltage traveling wave and the initial three-phase current traveling wave, calculate the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus The three-phase voltage traveling wave modulus and the corresponding three-phase current traveling wave modulus are respectively obtained, and the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus are respectively subjected to four-layer wavelet transformation, respectively according to their respective wavelet The corresponding wavelet transform modulus maxima are extracted from the transformation results; the wavelet transform modulus maxima of the three-phase voltage traveling wave moduli and the corresponding wavelet transform moduli of the three-phase current traveling wave moduli in each of the four layers Large value for polarity comparison; if there are at least three layers of three-phase voltage traveling wave modulus wavelet transform modulus maximum polarity and corresponding three-phase current traveling wave modulus wavelet transform modulus maximum polarity On the contrary, it is determined that the disturbance occurs at the non-power end of the relay.

In any of the above technical solutions, preferably, the three-phase voltage traveling wave modulus includes the three-phase voltage traveling wave linear mode component and/or the three-phase voltage traveling wave zero-mode component, and the three-phase current traveling wave modulus includes the three-phase electric current traveling wave modulus The linear mode component of the prevailing wave and/or the zero mode component of the three-phase current traveling wave.

In this technical solution, if a traveling wave disturbance occurs in the system, four layers of wavelet transformation are performed on the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus respectively, and the wavelet function here can choose three B samples The first-order derivative of the function. The corresponding modulus maxima are extracted according to the respective wavelet transform results. By comparing the polarity of the maximum value of the four-layer wavelet transform modulus of the voltage traveling wave modulus with the corresponding polarity of the four-layer wavelet transform modulus maximum of the current traveling wave modulus, it is judged whether the disturbance occurs at the non-power supply end of the relay.

Specifically, if a traveling wave disturbance is detected in the system, the initial three-phase voltage traveling wave and the initial three-phase current traveling wave are stored, such as 64 points of data before and after the disturbance. The phase-mode transformation is carried out on the three-phase voltage traveling wave, and the phase-mode transformation matrix adopts the Karen Bell matrix, so as to obtain the three-phase voltage traveling wave line-mode component and the three-phase voltage traveling wave zero-mode component. Similarly, the phase-mode transformation is performed on the three-phase current traveling wave, and the transformation matrix adopts the Karen Bell matrix, so as to obtain the three-phase current traveling wave line-mode component and the three-phase current traveling wave zero-mode component.

Compare the polarity of the four-level wavelet transform modulus maximum value of the voltage traveling wave linear mode component with the corresponding polarity of the four-level wavelet transform modulus maximum value of the current traveling wave line mode component, if there are no less than three layers of voltage traveling wave line mode components If the polarity of the wavelet transform modulus maxima of the corresponding current traveling wave linear mode component is opposite, it is determined that the disturbance occurs at the relay without power supply; or, compare the four-level wavelet transform modulus maxima of the voltage traveling wave zero-mode component The polarity of the wavelet transform modulus maxima of the four-layer wavelet transform of the current traveling wave zero-mode component, if there are no less than three layers of the voltage traveling wave zero-mode component and the wavelet transform modulus polarity of the current traveling wave zero-mode component are opposite, Then it is determined that the disturbance occurs at the non-power supply end of the relay; if none of the above is satisfied, it is determined that the disturbance occurs outside the protected line. Through the technical solution of the present invention, single-phase grounding faults and disturbances can be distinguished, thereby avoiding the problem in the related art that it is difficult to distinguish traveling waves generated by faults from traveling waves generated by system disturbances such as lightning strikes or even switching operations, and are prone to misoperation.

Those skilled in the art should understand that the real-time collected three-phase voltage traveling wave and three-phase current traveling wave data of 64 points before and after the disturbance are only one of the transient traveling wave data after the fault, but the transient traveling wave data after the fault Not limited to this.

In any of the above technical solutions, preferably, the fault unit is specifically used to: collect the three-phase power frequency voltage and the three-phase power frequency current at both ends of the line in real time; store the initial three-phase power frequency voltage and the initial three-phase power frequency current respectively , and perform phase sequence transformation on the initial three-phase power frequency voltage and initial three-phase power frequency current, respectively, to obtain the effective value of the power frequency zero-sequence voltage and the effective value of the three-phase power frequency current; compare the three-phase power frequency zero-sequence voltage effective Value and voltage setting value, if the effective value of the power frequency zero-sequence voltage is greater than the voltage setting value, it is determined that a single-phase ground fault occurs at the non-power end of the relay; when it is determined that a ground fault occurs at the non-power end of the relay, compare the three-phase power frequency current RMS value and current setting value, if the RMS value of each phase of the three-phase power frequency current is lower than the current setting value, it is determined that a single-phase ground fault has occurred at the non-power end of the relay.

After the ground fault occurs in the power line, the steady-state power frequency electrical quantity after the fault has changed significantly compared with that before the fault. Before the fault, the three phases are symmetrical, and the three-phase voltage is symmetrical and maintained near the rated voltage; the three-phase current is the load current, and there is no zero-sequence voltage and zero-sequence current. After a fault, the voltage and current will change significantly. In the non-effective neutral point grounding system, after a single-phase ground fault, the zero-sequence voltage increases, and the healthy phase-to-phase voltage increases, except for a short-circuit fault other than single-phase grounding, the fault phase current increases, and the fault phase voltage decreases.

In this technical solution, if a traveling wave disturbance occurs at the non-power end of the relay, the real-time collected initial three-phase power frequency voltage and initial three-phase power frequency current are stored, such as 24 points of data after the disturbance. Perform phase sequence transformation on the three-phase power frequency voltage and three-phase power frequency current to obtain the positive, negative and zero three-sequence components of the three-phase power frequency voltage respectively, and then use the Fourier transform to obtain the power frequency zero-sequence voltage The effective value and the effective value of the three-phase power frequency current. By comparing the effective value of the zero-sequence voltage with the voltage setting value, if the effective value of the zero-sequence voltage is greater than the voltage setting value, it is determined that a ground fault has occurred at the non-power end of the relay; If the effective value of the current is lower than the current setting value, it is determined that a single-phase ground fault has occurred at the non-power end of the relay.

Those skilled in the art should understand that the real-time collected three-phase power frequency voltage and three-phase power frequency current 24-point data after disturbance is only one of the steady-state power frequency data after the fault, but the steady-state power frequency data after the fault is not limited to this.

In any of the above technical solutions, preferably, the voltage setting value is equal to the product of the upper critical value of the zero-sequence voltage under normal system operation and the first preset coefficient; the current setting value is equal to the upper critical value of the load current under normal system operation The product of the value and the second preset coefficient.

In this technical solution, the voltage setting value is set by multiplying the maximum zero-sequence voltage amplitude that may occur under normal system operation with a reliability factor, and the current setting value is set according to the maximum load current that may occur under normal system operation and another Reliability coefficients are multiplied and set.

In the third aspect of the present invention, a computer device is proposed, including a memory, a processor, and a computer program stored on the memory and operable on the processor, and the processor is used to execute the steps of any one of the methods in the above technical solutions .

According to the computer equipment of the present invention, the processor contained in it is used to execute the steps of the single-phase ground traveling wave protection method in any of the above technical solutions, so the computer equipment can realize all the beneficial effects of the single-phase ground traveling wave protection method , which will not be repeated here.

In a fourth aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of any one of the methods in the above-mentioned technical solutions are realized.

According to the computer-readable storage medium of the present invention, when the computer program stored thereon is executed by the processor, the steps of the single-phase ground traveling wave protection method in any of the above-mentioned technical solutions are realized, so the computer-readable storage medium can realize the All the beneficial effects of the single-phase grounding traveling wave protection method will not be repeated here.

Additional aspects and advantages of the invention will become apparent in the description which follows, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 shows a schematic flow chart of a single-phase grounding traveling wave protection method according to an embodiment of the present invention;

Fig. 2 shows a schematic flow diagram of a single-phase ground traveling wave protection method according to another embodiment of the present invention;

Fig. 3 shows a schematic flowchart of a single-phase grounding traveling wave protection method according to yet another embodiment of the present invention;

Fig. 4 shows a schematic flowchart of a single-phase grounding traveling wave protection method according to yet another embodiment of the present invention;

Fig. 5 shows a schematic flowchart of a single-phase grounding traveling wave protection method according to yet another embodiment of the present invention;

Fig. 6 shows a schematic block diagram of a single-phase grounded traveling wave protection device according to an embodiment of the present invention;

Fig. 7 shows a schematic block diagram of a computer device according to an embodiment of the present invention.

Detailed ways

In order to understand the above-mentioned purpose, features and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described here. Therefore, the protection scope of the present invention is not limited by the specific details disclosed below. EXAMPLE LIMITATIONS.

As shown in FIG. 1 , it is a schematic flowchart of a single-phase grounding traveling wave protection method according to an embodiment of the present invention. Among them, the method includes:

Step 102, when a traveling wave disturbance occurs in the line, it is judged whether the disturbance occurs at the non-power supply end of the relay;

Step 104, when it is determined that the disturbance occurs at the non-power end of the relay, determine whether a single-phase ground fault occurs at the non-power end of the relay;

Step 106, when it is determined that a single-phase ground fault occurs, a trip signal is sent based on the time set according to the ladder-type principle;

Step 108, if the relay sends a trip command according to the trip signal, the relay on the non-power side of the line will send a trip command according to the detected change of the three-phase power frequency electrical quantity.

The single-phase grounding traveling wave protection method provided by the present invention is based on any branch line in a neutral point non-effective grounding system containing multi-section branch power lines (that is, a single-ended power supply radial distribution line broken by a single circuit breaker). Detect the traveling wave electrical quantity at both ends of the protected line, and judge whether there is a disturbance on the protected line. If a disturbance occurs, based on the polarity comparison of the initial traveling wave, determine which side of the relay the disturbance occurs on. At the power supply end, based on the power frequency electrical quantity, it is judged whether a single-phase ground fault has occurred at the non-power end of the relay, and the fault and disturbance are distinguished. If a single-phase ground fault occurs at the non-power end of the relay, it is based on Time delay waits for action. When the relay with the shortest time delay setting trips first, the faulty line is cut off from the power supply side, and the change of the three-phase power frequency electrical quantity sensed by the relay on the opposite end without power supply is specific. The relay on the power supply side will detect that the effective value of the three-phase current approaches zero, and use this as a criterion to issue a trip command to cut off the faulty line from the non-power supply side. Through the single-phase grounding traveling wave protection method of the present invention, not only can the single-phase grounding fault be detected accurately and quickly, but also the single-phase grounding fault can be quickly and selectively cut off from both ends of the faulty line, so as to realize the power line protection of the whole line successively and quickly It provides conditions for quick restoration of normal line power supply, improves the reliability of power line operation, and does not require communication channels, which has good economy and practicability.

The traveling wave in the embodiment of the present invention refers to the electromagnetic wave propagating in the power system caused by the disturbance of the power equipment in operation.

In the above-mentioned embodiment, preferably, the setting time is set according to the step-type principle, specifically: setting the corresponding setting time according to the distance between the relay and the power supply, wherein the closer the distance is, the longer the setting time is.

In this embodiment, the closer the relay is to the power source, the longer the corresponding setting time. If a traveling wave disturbance occurs in the system, judge which end of the relay the disturbance occurs at. If it occurs at the non-power end of the relay, when judging whether a single-phase ground fault occurs at the non-power end of the relay, if a single-phase ground fault occurs, each such The relays will act after a delay according to the corresponding setting time. When the relay with the shortest delay sends a trip command, the faulty line will be cut off from the power supply side, and the non-power side relay on the other side will use the three-phase power frequency electric current sensed According to the change of the quantity, a trip command is issued to cut off the faulty line from the non-power side. In this way, the power line protection can be activated sequentially across the entire line, accurately and quickly detect single-phase ground faults, and quickly and selectively remove single-phase ground faults from both ends of the line.

As shown in FIG. 2 , it is a schematic flowchart of a single-phase ground traveling wave protection method according to another embodiment of the present invention. Among them, the method includes:

Step 202, collecting the three-phase voltage traveling wave and the three-phase current traveling wave at both ends of the line in real time;

Step 204, comparing the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity with a preset threshold;

Step 206, if the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity is greater than a preset threshold, it is determined that a traveling wave disturbance occurs;

Step 208, judging whether the disturbance occurs at the non-power end of the relay;

Step 210, when it is determined that the disturbance occurs at the non-power end of the relay, determine whether a single-phase ground fault occurs at the non-power end of the relay;

Step 212, when it is determined that a single-phase ground fault occurs, a trip signal is sent based on the time set according to the ladder-type principle;

Step 214, if the relay sends a trip command according to the trip signal, the relay on the non-power side of the line will send a trip command according to the detected change of the three-phase power frequency electrical quantity.

In this embodiment, the three-phase voltage traveling wave and the three-phase current traveling wave on the protected line are synchronously collected in real time according to the preset sampling frequency (such as 1Mhz); the analog quantity of the real-time three-phase voltage traveling wave or the three-phase current traveling wave is The input level comparison circuit is compared with the preset threshold to judge whether traveling wave disturbance occurs in the system. Wherein, the setting of the threshold may be 200mv. Specifically, when the three-phase voltage traveling wave analog quantity or the three-phase voltage traveling wave analog quantity is greater than a preset threshold, it is determined that a traveling wave disturbance occurs in the system.

Those skilled in the art should understand that the sampling frequency is 1Mhz, but not limited thereto; the preset threshold is 200mv, but not limited thereto.

As shown in FIG. 3 , it is a schematic flowchart of a single-phase ground traveling wave protection method according to yet another embodiment of the present invention. Among them, the method includes:

Step 302, collecting the three-phase voltage traveling wave and the three-phase current traveling wave at both ends of the line in real time;

Step 304, comparing the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity with a preset threshold;

Step 306, if the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity is greater than a preset threshold, it is determined that a traveling wave disturbance occurs;

Step 308, respectively storing the initial three-phase voltage traveling wave and the initial three-phase current traveling wave, and calculating the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus;

Step 310, respectively performing four-layer wavelet transform on the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus, and extracting corresponding wavelet transform modulus maxima respectively according to the respective wavelet transform results;

Step 312, respectively comparing the polarity of the wavelet transform modulus maxima of the three-phase voltage traveling wave modulus of each of the four layers with the corresponding wavelet transform modulus maxima of the three-phase current traveling wave modulus;

Step 314, if the polarity of the wavelet transform modulus maxima of the three-phase voltage traveling wave moduli of at least three layers is opposite to the polarity of the wavelet transform modulus maxima of the corresponding three-phase current traveling wave moduli, determine The disturbance occurs at the non-powered end of the relay;

Step 316, when it is determined that the disturbance occurs at the non-power end of the relay, determine whether a single-phase ground fault occurs at the non-power end of the relay;

Step 318, when it is judged that a single-phase ground fault occurs, a trip signal is sent based on the time set according to the ladder-type principle;

Step 320, if the relay sends a trip command according to the trip signal, the relay on the non-power side of the line will send a trip command according to the detected change of the three-phase power frequency electrical quantity.

In any of the above embodiments, preferably, the three-phase voltage traveling wave modulus includes the three-phase voltage traveling wave linear mode component and/or the three-phase voltage traveling wave zero-mode component, and the three-phase current traveling wave modulus includes the three-phase electric current The linear mode component of the prevailing wave and/or the zero mode component of the three-phase current traveling wave.

In this embodiment, if it is detected that a traveling wave disturbance has occurred in the system, four layers of wavelet transformation are performed on the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus respectively, and the wavelet function here can be selected as three B-sample The first-order derivative of the function. The corresponding modulus maxima are extracted according to the respective wavelet transform results. By comparing the polarity of the maximum value of the four-layer wavelet transform modulus of the voltage traveling wave modulus with the corresponding polarity of the four-layer wavelet transform modulus maximum of the current traveling wave modulus, it is judged whether the disturbance occurs at the non-power supply end of the relay.

Specifically, if a traveling wave disturbance is detected in the system, the initial three-phase voltage traveling wave and the initial three-phase current traveling wave are stored, such as 64 points of data before and after the disturbance. The phase-mode transformation is carried out on the three-phase voltage traveling wave, and the phase-mode transformation matrix adopts the Karen Bell matrix, so as to obtain the three-phase voltage traveling wave line-mode component and the three-phase voltage traveling wave zero-mode component. Similarly, the phase-mode transformation is performed on the three-phase current traveling wave, and the transformation matrix adopts the Karen Bell matrix, so as to obtain the three-phase current traveling wave line-mode component and the three-phase current traveling wave zero-mode component.

Compare the polarity of the four-level wavelet transform modulus maximum value of the voltage traveling wave linear mode component with the corresponding polarity of the four-level wavelet transform modulus maximum value of the current traveling wave line mode component, if there are no less than three layers of voltage traveling wave line mode components If the polarity of the wavelet transform modulus maxima of the corresponding current traveling wave linear mode component is opposite, it is determined that the disturbance occurs at the relay without power supply; or, compare the four-level wavelet transform modulus maxima of the voltage traveling wave zero-mode component The polarity of the wavelet transform modulus maxima of the four-layer wavelet transform of the current traveling wave zero-mode component, if there are no less than three layers of the voltage traveling wave zero-mode component and the wavelet transform modulus polarity of the current traveling wave zero-mode component are opposite, Then it is determined that the disturbance occurs at the non-power supply end of the relay; if none of the above is satisfied, it is determined that the disturbance occurs outside the protected line. Through the embodiments of the present invention, single-phase grounding faults and disturbances can be distinguished, thereby avoiding the problem in the related art that it is difficult to distinguish traveling waves generated by faults from traveling waves generated by system disturbances, such as lightning strikes or even switching operations, and are prone to misoperation.

Those skilled in the art should understand that the real-time collected three-phase voltage traveling wave and three-phase current traveling wave data of 64 points before and after the disturbance are only one of the transient traveling wave data after the fault, but the transient traveling wave data after the fault Not limited to this.

As shown in FIG. 4 , it is a schematic flowchart of a single-phase ground traveling wave protection method according to another embodiment of the present invention. Among them, the method includes:

Step 402, collecting in real time the three-phase voltage traveling wave and the three-phase current traveling wave as well as the three-phase power frequency voltage and the three-phase power frequency current at both ends of the line;

Step 404, comparing the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity with a preset threshold;

Step 406, if the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity is greater than a preset threshold, it is determined that a traveling wave disturbance occurs in the system;

Step 408, respectively storing the initial three-phase voltage traveling wave and the initial three-phase current traveling wave, and calculating the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus;

Step 410, respectively performing four-layer wavelet transform on the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus, and extracting corresponding wavelet transform modulus maxima according to the respective wavelet transform results;

Step 412, respectively comparing the polarity of the wavelet transform modulus maxima of the three-phase voltage traveling wave moduli of each of the four layers with the corresponding wavelet transform modulus maxima of the three-phase current traveling wave moduli;

Step 414, if the polarity of the wavelet transform modulus maxima of the three-phase voltage traveling wave modulus of at least three layers is opposite to the polarity of the wavelet transform modulus maxima of the corresponding three-phase current traveling wave modulus, then determine The disturbance occurs at the non-powered end of the relay;

Step 416, respectively storing the initial three-phase power frequency voltage and the initial three-phase power frequency current, and performing phase sequence transformation on the initial three-phase power frequency voltage and the initial three-phase power frequency current, respectively, to obtain the effective value of the power frequency zero-sequence voltage and RMS value of three-phase power frequency current;

Step 418, comparing the effective value of the power frequency zero-sequence voltage with the voltage setting value, if the effective value of the power frequency zero-sequence voltage is greater than the voltage setting value, it is determined that a ground fault occurs at the non-power end of the relay;

Step 420, comparing the effective value of the three-phase power frequency current with the current setting value, if the effective value of each phase of the three-phase power frequency current is lower than the current setting value, then it is determined that the non-power end of the relay has a single-phase Ground Fault;

Step 422, sending a tripping signal based on the time set according to the ladder-type principle;

Step 424, if the relay sends a trip command according to the trip signal, the relay on the non-power side of the line will send a trip command according to the detected change of the three-phase power frequency electrical quantity.

In this embodiment, if it is detected that a traveling wave disturbance occurs at the non-power end of the relay, the real-time collected initial three-phase power frequency voltage and initial three-phase power frequency current, such as 24 points of data after the disturbance, are stored. Perform phase sequence transformation on the three-phase power frequency voltage and three-phase power frequency current to obtain the positive, negative and zero three-sequence components of the three-phase power frequency voltage, and then use the Fourier transform to obtain the effective zero-sequence voltage of the power frequency value and the effective value of the three-phase power frequency current. By comparing the effective value of the zero-sequence voltage with the voltage setting value, if the effective value of the zero-sequence voltage is greater than the voltage setting value, it is determined that a ground fault has occurred at the non-power end of the relay; If the effective value of the current is lower than the current setting value, it is determined that a single-phase ground fault has occurred at the non-power end of the relay.

Those skilled in the art should understand that the real-time collected three-phase power frequency voltage and three-phase power frequency current 24-point data after disturbance is only one of the steady-state power frequency data after the fault, but the steady-state power frequency data after the fault is not limited to this.

In any of the above embodiments, preferably, the voltage setting value is equal to the product of the upper critical value of the zero-sequence voltage under normal system operation and the first preset coefficient; the current setting value is equal to the upper critical value of the load current under normal system operation The product of the value and the second preset coefficient.

In this embodiment, the voltage setting value is set by multiplying the maximum zero-sequence voltage amplitude that may occur under normal system operation with a reliability factor, and the current setting value is set according to the maximum load current that may occur under normal system operation and another Reliability coefficients are multiplied and set.

Specific embodiments: a single-phase grounding protection method for power lines in a neutral point non-effectively grounded system is provided, as shown in Figure 5, the method specifically includes:

Step 502, collecting traveling wave electrical quantities and power frequency electrical quantities at both ends of the protected line in real time;

Step 504, based on the electrical quantities of traveling waves, it is judged whether traveling wave disturbances have occurred in the system;

Step 506, when it is determined that a traveling wave disturbance has occurred in the system, it is judged based on the polarity of the initial voltage and current traveling wave whether the disturbance occurs at the non-power supply end of the relay;

Step 508, when it is determined that the disturbance occurs at the non-power end, based on the power frequency electrical quantity, it is judged whether a single-phase ground fault has occurred at the non-power end of the relay;

Step 510, when it is determined that a single-phase ground fault has occurred, the relay first waits for action according to the time delay of the ladder type coordination;

Step 512, when the relay with the shortest time delay trips, the relay at the opposite end uses the change of the three-phase power frequency electrical quantity sensed to operate the relay.

In the single-phase grounding traveling wave protection method provided by the embodiment of the present invention, any branch line (that is, a distribution line disconnected by a single circuit breaker) in a neutral point non-effectively grounded system containing multi-section branch power lines is protected based on detection The traveling wave electrical quantity at both ends of the line is used to judge whether there is a disturbance on the protected line. If a disturbance occurs, based on the polarity comparison of the initial traveling wave, it is judged which side of the relay the disturbance occurs on. If it occurs on the non-power end of the relay, Based on the power frequency electrical quantity, judge whether a single-phase ground fault has occurred at the non-power end of the relay, and distinguish the fault from the disturbance. If a single-phase ground fault occurs at the non-power end of the relay, the time delay based on the ladder-type principle Waiting for the action, when the relay with a shorter time delay setting trips first, the non-power side relay at the opposite end of the faulty line uses the change of the three-phase power frequency electrical quantity sensed to issue a trip command. Through the single-phase grounding traveling wave protection method of the present invention, not only can the single-phase grounding fault be detected accurately and quickly, but also the single-phase grounding fault can be quickly and selectively cut off from both ends of the faulty line, so as to realize the power line protection of the whole line successively and quickly It provides conditions for quick restoration of normal line power supply, improves the reliability of power line operation, and does not require communication channels, which has good economy and practicability.

As shown in FIG. 6 , it is a schematic block diagram of a single-phase grounded traveling wave protection device according to an embodiment of the present invention. Wherein, the device 600 includes:

The disturbance unit 602 is used to determine whether the disturbance occurs at the non-power end of the relay when a traveling wave disturbance occurs in the line;

The fault unit 604 is used to determine whether a single-phase ground fault occurs at the non-power end of the relay when it is determined that the disturbance occurs at the non-power end of the relay;

The protection unit 606 is used to send a trip signal based on the time set according to the ladder-type principle when it is determined that a single-phase ground fault occurs;

The protection unit 606 is also used for if the relay sends a trip command according to the trip signal, the relay on the non-power side of the line will send a trip command according to the detected change of the three-phase power frequency electrical quantity.

The single-phase grounding traveling wave protection device 600 provided by the present invention is used for any branch line in the neutral point non-effective grounding system containing multi-section branch power lines (that is, single-ended power supply radial power distribution lines disconnected by a single circuit breaker), Based on the detection of the traveling wave electrical quantity at both ends of the protected line, it is judged whether there is a disturbance on the protected line. If a disturbance occurs, based on the polarity comparison of the initial traveling wave, it is judged which side of the relay the disturbance occurs on. At the non-power end, based on the power frequency electrical quantity, judge whether a single-phase ground fault has occurred at the non-power end of the relay, and distinguish the fault from the disturbance. When the relay with the shortest time delay setting trips first, the faulty line is cut off from the power supply side, and the relay on the opposite end without power supply uses the change of the three-phase power frequency electrical quantity that is felt specifically. The relay on the non-power side will detect that the effective value of the three-phase current approaches zero, and use this as a criterion to issue a trip command to cut off the faulty line from the non-power side. Through the single-phase grounding traveling wave protection method of the present invention, not only can the single-phase grounding fault be detected accurately and quickly, but also the single-phase grounding fault can be quickly and selectively cut off from both ends of the faulty line, so as to realize the power line protection of the whole line successively and quickly It provides conditions for quick restoration of normal line power supply, improves the reliability of power line operation, and does not require communication channels, which has good economy and practicability.

In the above-mentioned embodiment, preferably, the setting time is set according to the step-type principle, specifically: setting the corresponding setting time according to the distance between the relay and the power supply, wherein the closer the distance is, the longer the setting time is.

In this embodiment, the closer the relay is to the power source, the longer the corresponding setting time. If a traveling wave disturbance occurs in the system, judge which end of the relay the disturbance occurs at. If it occurs at the non-power end of the relay, when judging whether a single-phase ground fault occurs at the non-power end of the relay, if a single-phase ground fault occurs, each such The relays will act after a delay according to the corresponding setting time. When the relay with the shortest delay sends a trip command, the faulty line will be cut off from the power supply side, and the non-power side relay on the other side will use the three-phase power frequency electric current sensed According to the change of the quantity, a trip command is issued to cut off the faulty line from the non-power side. In this way, the power line protection can be activated sequentially across the entire line, accurately and quickly detect single-phase ground faults, and quickly and selectively remove single-phase ground faults from both ends of the line.

In any of the above embodiments, preferably, the disturbance unit 602 is specifically used to: collect the three-phase voltage traveling wave and the three-phase current traveling wave at both ends of the line in real time; convert the three-phase voltage traveling wave analog or the three-phase current traveling wave The analog quantity is compared with a preset threshold value, and if the three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity is greater than the preset threshold value, it is determined that a traveling wave disturbance occurs.

In this embodiment, the three-phase voltage traveling wave and the three-phase current traveling wave on the protected line are synchronously collected in real time according to the preset sampling frequency (such as 1Mhz); the analog quantity of the real-time three-phase voltage traveling wave or the three-phase current traveling wave is The input level comparison circuit is compared with the preset threshold to judge whether traveling wave disturbance occurs in the system. Wherein, the setting of the threshold may be 200mv. Specifically, when the three-phase voltage traveling wave analog quantity or the three-phase voltage traveling wave analog quantity is greater than a preset threshold, it is determined that a traveling wave disturbance occurs in the system.

Those skilled in the art should understand that the sampling frequency is 1Mhz, but not limited thereto; the preset threshold is 200mv, but not limited thereto.

In any of the above-mentioned embodiments, preferably, the disturbance unit 602 is also specifically used to: respectively store the initial three-phase voltage traveling wave and the initial three-phase current traveling wave, and calculate the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus; obtain the three-phase voltage traveling wave modulus and the corresponding three-phase current traveling wave modulus respectively, respectively carry out the four-layer wavelet transform on the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus, respectively according to their respective The corresponding wavelet transform modulus maxima are extracted from the wavelet transform results; the wavelet transform modulus maxima of the three-phase voltage traveling wave modulus and the wavelet transform moduli of the corresponding three-phase current traveling wave moduli in each of the four layers are respectively Maximum value for polarity comparison; if there are at least three layers of three-phase voltage traveling wave modulus wavelet transform modulus maximum polarity and corresponding three-phase current traveling wave modulus wavelet transform modulus maximum polarity If the property is opposite, it is determined that the disturbance occurs at the non-power end of the relay.

In any of the above embodiments, preferably, the three-phase voltage traveling wave modulus includes the three-phase voltage traveling wave linear mode component and/or the three-phase voltage traveling wave zero-mode component, and the three-phase current traveling wave modulus includes the three-phase electric current traveling wave modulus The linear mode component of the prevailing wave and/or the zero mode component of the three-phase current traveling wave.

In this embodiment, if it is detected that a traveling wave disturbance has occurred in the system, four layers of wavelet transformation are performed on the three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus respectively, and the wavelet function here can be selected as three B-sample The first-order derivative of the function. The corresponding modulus maxima are extracted according to the respective wavelet transform results. By comparing the polarity of the maximum value of the four-layer wavelet transform modulus of the voltage traveling wave modulus with the corresponding polarity of the four-layer wavelet transform modulus maximum of the current traveling wave modulus, it is judged whether the disturbance occurs at the non-power supply end of the relay.

Specifically, if a traveling wave disturbance is detected in the system, the initial three-phase voltage traveling wave and the initial three-phase current traveling wave are stored, such as 64 points of data before and after the disturbance. The phase-mode transformation is carried out on the three-phase voltage traveling wave, and the phase-mode transformation matrix adopts the Karen Bell matrix, so as to obtain the three-phase voltage traveling wave line-mode component and the three-phase voltage traveling wave zero-mode component. Similarly, the phase-mode transformation is performed on the three-phase current traveling wave, and the transformation matrix adopts the Karen Bell matrix, so as to obtain the three-phase current traveling wave line-mode component and the three-phase current traveling wave zero-mode component.

Compare the polarity of the four-level wavelet transform modulus maximum value of the voltage traveling wave linear mode component with the corresponding polarity of the four-level wavelet transform modulus maximum value of the current traveling wave line mode component, if there are no less than three layers of voltage traveling wave line mode components If the polarity of the wavelet transform modulus maxima of the corresponding current traveling wave linear mode component is opposite, it is determined that the disturbance occurs at the relay without power supply; or, compare the four-level wavelet transform modulus maxima of the voltage traveling wave zero-mode component The polarity of the wavelet transform modulus maxima of the four-layer wavelet transform of the current traveling wave zero-mode component, if there are no less than three layers of the voltage traveling wave zero-mode component and the wavelet transform modulus polarity of the current traveling wave zero-mode component are opposite, Then it is determined that the disturbance occurs at the non-power supply end of the relay; if none of the above is satisfied, it is determined that the disturbance occurs outside the protected line. Through the embodiments of the present invention, single-phase grounding faults and disturbances can be distinguished, thereby avoiding the problem in the related art that it is difficult to distinguish traveling waves generated by faults from traveling waves generated by system disturbances, such as lightning strikes or even switching operations, and are prone to misoperation.

Those skilled in the art should understand that the real-time collected three-phase voltage traveling wave and three-phase current traveling wave data of 64 points before and after the disturbance are only one of the transient traveling wave data after the fault, but the transient traveling wave data after the fault Not limited to this.

In any of the above embodiments, preferably, the fault unit 604 is specifically configured to: collect the three-phase power frequency voltage and the three-phase power frequency current at both ends of the line in real time; store the initial three-phase power frequency voltage and the initial three-phase power frequency respectively current, and perform phase sequence transformation on the initial three-phase power frequency voltage and initial three-phase power frequency current, respectively, to obtain the effective value of the power frequency zero-sequence voltage and the effective value of the three-phase power frequency current; compare the three-phase power frequency zero-sequence voltage Effective value and voltage setting value, if the effective value of the power frequency zero-sequence voltage is greater than the voltage setting value, it is determined that a single-phase ground fault occurs at the non-power end of the relay; when it is determined that a ground fault occurs at the non-power end of the relay, compare the three-phase power frequency current If the effective value of the three-phase power frequency current is lower than the current setting value, it is determined that a single-phase ground fault has occurred at the non-power end of the relay.

After the ground fault occurs in the power line, the steady-state power frequency electrical quantity after the fault has changed significantly compared with that before the fault. Before the fault, the three phases are symmetrical, and the three-phase voltage is symmetrical and maintained near the rated voltage; the three-phase current is the load current, and there is no zero-sequence voltage and zero-sequence current. After a fault, the voltage and current will change significantly. In the non-effective neutral point grounding system, after a single-phase ground fault, the zero-sequence voltage increases, and the healthy phase-to-phase voltage increases, except for a short-circuit fault other than single-phase grounding, the fault phase current increases, and the fault phase voltage decreases.

In this embodiment, if it is detected that a traveling wave disturbance occurs at the non-power end of the relay, the real-time collected initial three-phase power frequency voltage and initial three-phase power frequency current, such as 24 points of data after the disturbance, are stored. Perform phase sequence transformation on the three-phase power frequency voltage and three-phase power frequency current to obtain the positive, negative and zero three-sequence components of the three-phase power frequency voltage respectively, and then use the Fourier transform to obtain the power frequency zero-sequence voltage The effective value and the effective value of the three-phase power frequency current. By comparing the effective value of the zero-sequence voltage with the voltage setting value, if the effective value of the zero-sequence voltage is greater than the voltage setting value, it is determined that a ground fault has occurred at the non-power end of the relay; If the effective value of the current is lower than the current setting value, it is determined that a single-phase ground fault has occurred at the non-power end of the relay.

Those skilled in the art should understand that the real-time collected three-phase power frequency voltage and three-phase power frequency current 24-point data after disturbance is only one of the steady-state power frequency data after the fault, but the steady-state power frequency data after the fault is not limited to this.

In any of the above embodiments, preferably, the voltage setting value is equal to the product of the upper critical value of the zero-sequence voltage under normal system operation and the first preset coefficient; the current setting value is equal to the upper critical value of the load current under normal system operation The product of the value and the second preset coefficient.

In this embodiment, the voltage setting value is set by multiplying the maximum zero-sequence voltage amplitude that may occur under normal system operation with a reliability factor, and the current setting value is set according to the maximum load current that may occur under normal system operation and another Reliability coefficients are multiplied and set.

As shown in FIG. 7 , a schematic diagram of a computer device according to an embodiment of the present invention. The computer device 1 includes a memory 12, a processor 14, and a computer program stored in the memory 12 and operable on the processor 14, and the processor 14 is used to execute the steps of any one of the methods in the above-mentioned embodiments.

In the computer equipment 1 provided by the present invention, the processor 14 contained in it is used to execute the steps of the single-phase ground traveling wave protection method in any of the above-mentioned embodiments, so the computer equipment 1 can realize the single-phase ground traveling wave protection method All the beneficial effects of this will not be repeated here.

The embodiment of the fourth aspect of the present invention provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps of any one of the methods in the above-mentioned embodiments are implemented.

In the computer-readable storage medium provided by the present invention, when the computer program stored thereon is executed by the processor, the steps of the single-phase ground traveling wave protection method in any of the above-mentioned embodiments are realized, so the computer-readable storage medium can realize the All the beneficial effects of the single-phase grounding traveling wave protection method will not be repeated here.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (16)

1. a kind of single-phase earthing traveling-wave protection method, which is characterized in that including：

It is disturbed when traveling wave occurs for circuit, judges whether disturbance is happened at the non-transformer end of the circuit switching electric appliance；

When judging to disturb the non-transformer end for being happened at the relay, it is single-phase to judge whether the non-transformer end of the relay occurs Earth fault；

When judgement generation singlephase earth fault, trip signal is sent out based on the time adjusted according to stepped principle；

If the relay sends out trip signal according to the trip signal, the relay of circuit non-transformer side will basis The situation of change of the three-phase main-frequency electrical quantity detected, sends out trip signal.

2. single-phase earthing traveling-wave protection method according to claim 1, which is characterized in that described whole according to stepped principle The fixed time, specially：

According to the relay, corresponding setting time is set at a distance from power supply, it is described when adjusting wherein the distance is closer Between it is longer.

3. single-phase earthing traveling-wave protection method according to claim 1, which is characterized in that the method further includes：

The three-phase voltage traveling wave and three-phase current traveling wave at the circuit both ends are acquired in real time；

The three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity are compared with predetermined threshold value, if described Three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity are more than the predetermined threshold value, then judge that traveling wave, which occurs, disturbs It is dynamic.

4. single-phase earthing traveling-wave protection method according to claim 1, which is characterized in that described to judge whether disturbance occurs The non-transformer end of the relay the step of, including：

Storing initial three-phase voltage traveling wave and initial three-phase current traveling wave respectively calculate the three-phase voltage traveling wave modulus and described Three-phase current traveling wave modulus；

The three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus are subjected to four layers of wavelet transformation respectively, respectively basis Respective wavelet transform result extracts corresponding wavelet modulus maxima；

Respectively to the wavelet modulus maxima of each layer of three-phase voltage traveling wave modulus in four layers and corresponding three-phase electricity prevalence The wavelet modulus maxima of wave modulus carries out Polarity comparision；

If having the polarity and corresponding three-phase electricity of at least wavelet modulus maxima of three layers of the three-phase voltage traveling wave modulus The polarity of the wavelet modulus maxima of traveling wave modulus is flowed on the contrary, then judging that disturbance is happened at the non-transformer end of the relay.

5. single-phase earthing traveling-wave protection method according to claim 4, which is characterized in that

The three-phase voltage traveling wave modulus includes three-phase voltage traveling wave Aerial mode component and/or three-phase voltage traveling wave zero _exit；

The three-phase current traveling wave modulus includes three-phase current traveling wave Aerial mode component and/or three-phase current traveling wave zero _exit.

6. single-phase earthing traveling-wave protection method according to any one of claim 1 to 5, which is characterized in that the judgement The step of whether the non-transformer end of the relay occurs singlephase earth fault, including：

The three-phase main-frequency voltage and three-phase main-frequency electric current at the circuit both ends are acquired in real time；

Storing initial three-phase main-frequency voltage and initial three-phase main-frequency electric current respectively, and to the initial three-phase main-frequency voltage and described Initial three-phase main-frequency electric current carries out Phase-Sequence Transformation respectively, obtain power frequency residual voltage virtual value and three-phase main-frequency electric current it is effective Value；

Compare the power frequency residual voltage virtual value and voltage setting valve, if the power frequency residual voltage virtual value is more than or equal to institute Voltage setting valve is stated, then judges that earth fault occurs for the non-transformer end of the relay；

When the non-transformer end generation earth fault for judging the relay, the virtual value and electric current of the three-phase main-frequency electric current Setting valve judges if the virtual value of each phase power current is below the current setting in the three-phase main-frequency electric current Singlephase earth fault occurs for the non-transformer end of the relay.

7. control method according to claim 6, which is characterized in that the method further includes：

The voltage setting valve be equal to the residual voltage under the system normal operation upper critical value and the first predetermined coefficient it Product；

The current setting be equal to the load current under the system normal operation upper critical value and the second predetermined coefficient it Product.

8. a kind of single-phase earthing traveling-wave protection device, which is characterized in that including：

Disturb unit, for when circuit occur traveling wave disturbance, judge disturbance whether be happened at the circuit switching electric appliance without electricity Source；

Trouble unit, the non-transformer end for being happened at the relay when judgement disturbance, judges the non-transformer of the relay Whether end occurs singlephase earth fault；

Protection location sends out tripping for singlephase earth fault to occur when judgement based on the time adjusted according to stepped principle Signal；

The protection location, if be additionally operable to the relay sends out trip signal according to the trip signal, the circuit is without electricity The relay of source will send out trip signal according to the situation of change of the three-phase main-frequency electrical quantity detected.

9. single-phase earthing traveling-wave protection method according to claim 8, which is characterized in that described whole according to stepped principle The fixed time, specially：

According to the relay, corresponding setting time is set at a distance from power supply, it is described when adjusting wherein the distance is closer Between it is longer.

10. single-phase earthing traveling-wave protection device according to claim 8, which is characterized in that the disturbance unit, it is specific to use In：

The three-phase voltage traveling wave and three-phase current traveling wave at the circuit both ends are acquired in real time；

The three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity are compared with predetermined threshold value, if described Three-phase voltage traveling wave analog quantity or the three-phase current traveling wave analog quantity are more than the predetermined threshold value, then judge that traveling wave, which occurs, disturbs It is dynamic.

11. single-phase earthing traveling-wave protection method according to claim 8, which is characterized in that the disturbance unit, it is specific to go back For：

Storing initial three-phase voltage traveling wave and initial three-phase current traveling wave respectively calculate the three-phase voltage traveling wave modulus and described Three-phase current traveling wave modulus；

The three-phase voltage traveling wave modulus and the three-phase current traveling wave modulus are subjected to four layers of wavelet transformation respectively, respectively basis Respective wavelet transform result extracts corresponding wavelet modulus maxima；

Respectively to the wavelet modulus maxima of each layer of three-phase voltage traveling wave modulus in four layers and corresponding three-phase electricity prevalence The wavelet modulus maxima of wave modulus carries out Polarity comparision；

If having the polarity and corresponding three-phase electricity of at least wavelet modulus maxima of three layers of the three-phase voltage traveling wave modulus The polarity of the wavelet modulus maxima of traveling wave modulus is flowed on the contrary, then judging that disturbance is happened at the non-transformer end of the relay.

12. single-phase earthing traveling-wave protection method according to claim 11, which is characterized in that

The three-phase voltage traveling wave modulus includes three-phase voltage traveling wave Aerial mode component and/or three-phase voltage traveling wave zero _exit；

The three-phase current traveling wave modulus includes three-phase current traveling wave Aerial mode component and/or three-phase current traveling wave zero _exit.

13. the single-phase earthing traveling-wave protection device according to any one of claim 8 to 12, which is characterized in that the event Hinder unit, is specifically used for：

The three-phase main-frequency voltage and three-phase main-frequency electric current at the circuit both ends are acquired in real time；

Storing initial three-phase main-frequency voltage and initial three-phase main-frequency electric current respectively, and to the initial three-phase main-frequency voltage and described Initial three-phase main-frequency electric current carries out Phase-Sequence Transformation respectively, obtain power frequency residual voltage virtual value and three-phase main-frequency electric current it is effective Value；

Compare the power frequency residual voltage virtual value and voltage setting valve, if the power frequency residual voltage virtual value is more than or equal to institute Voltage setting valve is stated, then judges that earth fault occurs for the non-transformer end of the relay；

When earth fault, the virtual value and current setting of the three-phase main-frequency electric current, if institute occur for the judgement system The virtual value for stating each phase power current in three-phase main-frequency electric current is below the current setting, then judges the relay Singlephase earth fault occurs for non-transformer end.

14. control device according to claim 13, which is characterized in that

The voltage setting valve be equal to the residual voltage under the system normal operation upper critical value and the first predetermined coefficient it Product；

The current setting be equal to the load current under the system normal operation upper critical value and the second predetermined coefficient it Product.

15. a kind of computer equipment, including memory, processor and it is stored on the memory and can be on the processor The computer program of operation, which is characterized in that the processor is for executing such as any one of claim 1 to 7 the method The step of.

16. a kind of computer readable storage medium, is stored thereon with computer program, which is characterized in that the computer program It is realized when being executed by processor such as the step of any one of claim 1 to 7 the method.