CN114660505A - Power distribution system ground fault disappearance detection method and device and computer equipment - Google Patents
Power distribution system ground fault disappearance detection method and device and computer equipment Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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- G01R31/08—Locating faults in cables, transmission lines, or networks
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Abstract
The embodiment of the invention discloses a method and a device for detecting the disappearance of a ground fault of a power distribution system and computer equipment, wherein the method comprises the following steps: controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value; detecting zero sequence impedance of a neutral point of a power distribution system in real time, and determining the maximum value of the variation of the zero sequence impedance; determining whether the ground fault of the power distribution system disappears or not according to the maximum value of the variation and a preset variation setting value; and when the ground fault of the power distribution system disappears, controlling the flexible grounding device to stop compensating the ground fault of the power distribution system. The method can sensitively judge that the ground fault disappears without detecting the zero sequence current amplitude and the phase of each outgoing line, solves the problems of complex detection and low reliability of the prior art for the disappearance of the ground fault, has the capability of monitoring the disappearance of the ground fault in real time, has simple detection principle, does not need complex direction judgment, and can realize the automatic withdrawal of the compensation output of the flexible grounding device.
Description
Technical Field
The invention relates to the technical field of power distribution network flexible grounding system ground fault disappearance detection, in particular to a power distribution system ground fault disappearance detection method and device and computer equipment.
Background
The neutral point of the power distribution network is grounded by an active flexible device and is widely applied to power distribution systems of 66kV and below at home and abroad. The active flexible grounding mode of the power distribution network completely compensates the current of the grounding fault point, forces the fault to extinguish the arc, reduces the arc grounding overvoltage, and eliminates the risks of electric shock, fire and power failure caused by the grounding fault.
However, when the active flexible grounding device operates in the full compensation state, the full compensation state is not affected by the impedance value of the fault point. Therefore, the ground fault disappears, the active flexible grounding device cannot sense and detect, the traditional method detects the disappearance of the ground fault by adjusting the compensation voltage or current to judge the amplitude and the phase of the zero sequence current of the line, the method needs to access the zero sequence current of each line, the complexity and the uncertainty of the device detection are increased, and the method is not applied yet. The method for judging whether the zero sequence voltage exists by the output of the exiting device widely adopted at present reduces the using effect of the flexible grounding device.
Therefore, a method for accurately detecting the disappearance of the ground fault during active full compensation is urgently needed, so that the flexible grounding device can automatically quit the compensation.
Disclosure of Invention
The invention mainly aims to provide a power distribution system ground fault disappearance detection method, a power distribution system ground fault disappearance detection device and computer equipment, and can solve the problem that a flexible grounding device can automatically quit compensation in the prior art.
In order to achieve the above object, a first aspect of the present invention provides a method for detecting disappearance of ground fault in a power distribution system, the method including:
controlling a flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, wherein the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground fault;
detecting zero sequence impedance of a neutral point of the power distribution system in real time, and determining the maximum value of the variation of the zero sequence impedance;
determining whether the ground fault of the power distribution system disappears or not according to the maximum variation and a preset variation setting value;
and when the ground fault of the power distribution system disappears, controlling the flexible grounding device to stop compensating the ground fault of the power distribution system.
In one possible implementation, the detecting zero-sequence impedance of a neutral point of the power distribution system in real time and determining a maximum value of a variation of the zero-sequence impedance include:
acquiring the maximum value of the zero-sequence impedance and the minimum value of the zero-sequence impedance;
obtaining a zero sequence impedance difference value by using the maximum value of the zero sequence impedance and the minimum value of the zero sequence impedance as a difference;
and taking the zero sequence impedance difference value as the maximum value of the variable quantity.
In a possible implementation manner, the determining whether the ground fault of the power distribution system disappears according to the maximum variation and a preset variation setting includes:
when the maximum value of the variation is less than or equal to the variation setting value, determining that the ground fault disappears;
and when the maximum value of the variation is larger than the setting value of the variation, determining that the ground fault does not disappear.
In a possible implementation manner, the flexible grounding device is further configured to detect a ground fault condition of the power distribution system, where the ground fault condition includes that the power distribution system has a ground fault or does not have a ground fault, and the flexible grounding device is controlled to adjust an output voltage, and the method further includes:
detecting a ground fault condition of the power distribution system with the flexible grounding device;
when the flexible grounding device detects that the grounding fault condition of the power distribution system is the occurrence of the grounding fault, controlling the flexible grounding device to operate in a full compensation state, wherein the full compensation state is used for completely compensating the grounding fault current of the power distribution system;
recording the compensation time of the flexible grounding device in a full compensation state;
and when the compensation time is equal to a preset time threshold, executing the step of controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value.
In one possible implementation, the calculation formula of the zero sequence impedance is as follows:
wherein the content of the first and second substances,
is the output voltage of the flexible grounding device,
is the zero sequence current of the neutral point of the distribution system, | | is the module value of the zero sequence impedance.
In one possible implementation, the calculation formula of the zero sequence current of the neutral point of the power distribution system is as follows:
wherein the content of the first and second substances,
is the output voltage of the flexible grounding device,
zero sequence current, Z, for the neutral point of a power distribution systemsIs the internal impedance of the power supply of the flexible grounding device,
for fault phase supply voltage, x is a phase a, b or c, ZfFor fault versus ground impedance, ZcIs the non-fault phase-to-ground impedance.
In a possible implementation, when the ground fault does not disappear, the zero-sequence impedance is calculated as follows:
wherein, the first and the second end of the pipe are connected with each other,
is the output voltage of the flexible earthing device, ZsIs the internal impedance of the power supply of the flexible grounding device,
for fault phase supply voltage, x is a phase a, b or c, ZfFor fault versus ground impedance, ZcIs a non-fault phase-to-ground impedance.
In one possible implementation, when the ground fault disappears, the calculation formula of the zero-sequence impedance is as follows:
wherein Z issInternal impedance of power supply, Z, for flexible earthing meanscIs the non-fault phase-to-ground impedance.
In order to achieve the above object, a second aspect of the present invention provides an apparatus for detecting disappearance of ground fault in an electrical distribution system, the apparatus comprising:
an output voltage adjustment module: the flexible grounding device is used for controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, and the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has a ground fault;
zero sequence impedance detection module: the zero-sequence impedance detection device is used for detecting the zero-sequence impedance of a neutral point of the power distribution system in real time and determining the maximum value of the variation of the zero-sequence impedance;
a failure disappearance detection module: the device is used for determining whether the ground fault of the power distribution system disappears or not according to the maximum variation and a preset variation setting value;
a stop fault compensation module: and the flexible grounding device is used for controlling the flexible grounding device to stop compensating the ground fault of the power distribution system when the ground fault of the power distribution system disappears.
To achieve the above object, a third aspect of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps as shown in the first aspect and any possible implementation manner.
To achieve the above object, a fourth aspect of the present invention provides a computer device, including a memory and a processor, the memory storing a computer program, the computer program, when executed by the processor, causing the processor to perform the steps as shown in the first aspect and any possible implementation manner.
The embodiment of the invention has the following beneficial effects:
the invention provides a power distribution system ground fault disappearance detection method, which comprises the following steps: controlling a flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, wherein the flexible grounding device is used for performing ground fault compensation on a power distribution system when the power distribution system has a ground fault; detecting zero sequence impedance of a neutral point of a power distribution system in real time, and determining the maximum value of the variable quantity of the zero sequence impedance; determining whether the ground fault of the power distribution system disappears or not according to the maximum value of the variation and a preset variation setting value; and when the ground fault of the power distribution system disappears, controlling the flexible grounding device to stop compensating the ground fault of the power distribution system. The method can sensitively judge that the ground fault disappears without detecting the zero sequence current amplitude and the phase of each outgoing line, solves the problems of complex detection and low reliability of the prior art for the disappearance of the ground fault, has the capability of monitoring the disappearance of the ground fault in real time, has simple detection principle, does not need complex direction judgment, can realize the automatic exit of compensation output of the flexible grounding device, and has stronger engineering applicability.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Wherein:
fig. 1 is a flowchart of a method for detecting loss of ground fault of a power distribution system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of an electrical connection of a power distribution system according to an embodiment of the present invention;
fig. 3 is another flowchart of a method for detecting loss of ground fault in a power distribution system according to an embodiment of the present invention;
FIG. 4 is a simplified electrical connection schematic of an electrical distribution system according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an equivalent circuit for performing ground fault disappearance detection analysis on a power distribution system according to an embodiment of the invention;
fig. 6 is a block diagram of a device for detecting loss of ground fault of a power distribution system according to an embodiment of the present invention;
FIG. 7 is a block diagram of a computer device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a flowchart of a method for detecting disappearance of ground fault in a power distribution system according to an embodiment of the present invention, where the method shown in fig. 1 may be applied to a server or a terminal, and the terminal may be a controller or any electronic device with logic processing capability, which is not limited by this example, and the following method is exemplified by being applied to the terminal, and the method shown in fig. 1 may include the following steps:
101. controlling a flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, wherein the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground fault;
102. detecting zero sequence impedance of a neutral point of the power distribution system in real time, and determining the maximum value of the variation of the zero sequence impedance;
it should be noted that the method shown in fig. 1 may be specifically applied to the scenario of a power distribution system, for example, referring to fig. 2, fig. 2 is a schematic diagram of electrical connection of a power distribution system in an embodiment of the present invention, the power distribution system shown in fig. 2 may be a power distribution network flexible grounding system, the power distribution system includes a flexible grounding device, a bus 1, a line L1, a line L2, and a line L3, a distributed capacitance to ground of each line is C, where a loan fault exists in the line L3, a fault point thereof is f,
is the output voltage of the flexible grounding device. The flexible grounding device is used for detecting which line of the power distribution system has a ground fault and performing ground fault compensation on the power distribution system when the power distribution system has the ground fault.
In this embodiment, zero sequence impedance Z through neutral is required0To determine whether the ground fault disappears, the flexible grounding device needs to be controlled to adjust the value according to the preset voltage
Adjusting output voltage of flexible grounding device
And real-time zero-sequence impedance Z to neutral point of power distribution system in adjustment process of output voltage of power distribution system0The current state of the power distribution system is reflected by the change of the zero sequence impedance, and particularly, the current state of the power distribution system can be reflected by the change amount delta Z of the zero sequence impedance0Determining the variation amount Delta Z of the zero-sequence impedance0To obtain the maximum value of the variation amount DeltaZ0max. The zero sequence impedance is a ratio of zero sequence voltage to zero sequence current of a neutral point of the power distribution system in the process of adjusting output by the flexible grounding device. Wherein the amount of adjustment
With earth-fault resistance ZfThe size is relevant.
103. Determining whether the ground fault of the power distribution system disappears or not according to the maximum variation and a preset variation setting value;
it should be noted that, since the zero-sequence impedance is a ratio of zero-sequence voltage to zero-sequence current of a neutral point of the power distribution system in the process of adjusting the output of the flexible grounding device, the zero-sequence impedance may be used to reflect a current operation state of the power distribution system, and further, a variation may reflect a variation degree of the operation state of the power distribution system. Therefore, whether the ground fault of the power distribution system disappears can be judged through the maximum value of the variation, and specifically, whether the ground fault of the power distribution system disappears can be judged according to the maximum value delta Z of the variation0maxAnd a preset variation setting value delta Z0zdAnd determining whether the ground fault of the power distribution system disappears. Further, the larger the ground fault resistance Zf is, the larger the required neutral point variation amount setting value Δ Z is0zdThe larger theThe setting value Delta Z of the variation0zdAccording to the sensitivity, the sensitivity is set to be any value larger than 0.01K0, K0 is a sensitivity coefficient, and K0 is larger than 1.
104. And when the ground fault of the power distribution system disappears, controlling the flexible grounding device to stop compensating the ground fault of the power distribution system.
Further, when the ground fault of the power distribution system disappears, the flexible grounding device is controlled to stop compensating the ground fault of the power distribution system. And furthermore, the flexible grounding device can be controlled to stop compensating the grounding fault of the power distribution system without the participation of technicians. It should be noted that, the executing main body of the present application may be a controller, and when the controller is a control device of the flexible grounding device, the flexible grounding device may further implement automatic stop of ground fault compensation for the power distribution system, so as to implement an effect of automatically exiting ground fault compensation.
The invention provides a power distribution system ground fault disappearance detection method, which comprises the following steps: controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, wherein the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground faults; detecting zero sequence impedance of a neutral point of a power distribution system in real time, and determining the maximum value of the variation of the zero sequence impedance; determining whether the ground fault of the power distribution system disappears or not according to the maximum value of the variation and a preset variation setting value; and when the ground fault of the power distribution system disappears, controlling the flexible grounding device to stop compensating the ground fault of the power distribution system. The method can sensitively judge that the ground fault disappears without detecting the zero sequence current amplitude and the phase of each outgoing line, solves the problems of complex detection and low reliability of the prior art on the disappearance of the ground fault, has the capability of monitoring the disappearance of the ground fault in real time, has simple detection principle, does not need complex direction judgment, can realize the automatic exit of compensation output of the flexible grounding device, and has strong engineering applicability.
Referring to fig. 3, fig. 3 is another flowchart of a method for detecting disappearance of ground fault in a power distribution system according to an embodiment of the present invention, where the method shown in fig. 3 includes the following steps:
301. controlling a flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, wherein the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground fault;
it should be noted that the content of step 301 is similar to that of step 101 shown in fig. 1, and is a surface repetition, which is not described herein again, and reference may be made to the content of step 301.
In a possible implementation, the flexible grounding device is further configured to detect a ground fault condition of the power distribution system, where the ground fault condition includes a ground fault or no fault in the power distribution system, and the flexible grounding device is controlled to adjust the output voltage, and the following steps a1-a4 may be further included:
a1, detecting the ground fault condition of the power distribution system by using the flexible grounding device;
a2, when the flexible grounding device detects that the ground fault condition of the power distribution system is the occurrence of ground fault, controlling the flexible grounding device to operate in a full compensation state, wherein the full compensation state is used for fully compensating the ground fault current of the power distribution system;
it should be noted that, the flexible grounding device may be used to detect a ground fault condition of the power distribution system, and when a ground fault occurs in the power distribution system, the flexible grounding device may also be used to compensate the ground fault, and may control the flexible grounding device to operate in a full compensation state, where the flexible grounding device operates in the full compensation state, and the voltage current state is that the ground fault point current is close to 0 and the fault phase voltage is close to 0.
A3, recording the compensation time of the flexible grounding device in a full compensation state;
and A4, when the compensation time is equal to a preset time threshold, executing the step of controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value.
When the flexible grounding device starts to be in a full compensation state, the compensation time of the flexible grounding device in the full compensation state can be recorded, wherein when the compensation time is equal to a preset time threshold T, the step of controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value is started, wherein the preset time threshold is the full compensation set time T of the flexible grounding device in the full compensation state, and the time threshold T is usually set to be between 1s and 10s according to the instantaneous fault arc quenching time of a system. When the time T is reached, the output voltage of the flexible grounding device is actively adjusted
302. Detecting zero sequence impedance of a neutral point of the power distribution system in real time, and determining the maximum value of the variation of the zero sequence impedance;
it should be noted that the content shown in step 302 is similar to the content of step 102 shown in fig. 1, and for avoiding repetition, details are not repeated here, and specifically, reference may be made to the content of step 102 shown in fig. 1.
In one possible implementation, the step 302 may include steps B1-B3:
b1, acquiring the maximum value of the zero sequence impedance and the minimum value of the zero sequence impedance;
b2, obtaining a zero sequence impedance difference value by using the maximum value of the zero sequence impedance and the minimum value of the zero sequence impedance as a difference;
and B3, taking the zero sequence impedance difference value as the maximum value of the variation.
The zero-sequence impedance is detected in real time in the voltage adjustment process, so that a zero-sequence impedance value at each moment can be obtained, and the maximum value and the minimum value of the zero-sequence impedance can be obtained. The maximum value of the variation of the zero-sequence impedance can be obtained through the maximum value of the zero-sequence impedance and the minimum value of the zero-sequence impedance. Specifically, the zero sequence impedance difference value between the maximum value of the zero sequence impedance and the minimum value of the zero sequence impedance can be obtained by subtracting the maximum value from the minimum value of the zero sequence impedance, and therefore, the zero sequence impedance difference value can be used as the maximum value of the variation.
For example, the calculation formula of the zero sequence impedance may refer to the following:
wherein the content of the first and second substances,
is the output voltage of the flexible grounding device,
is the zero sequence current of the neutral point of the distribution system, | | is the module value of the zero sequence impedance.
Further, please refer to fig. 4, wherein fig. 4 is a simplified electrical connection diagram of a power distribution system according to an embodiment of the present invention; wherein the wiring system shown in fig. 2 can be simplified to the structure shown in fig. 4, and fig. 4 includes a phase a, a phase B, and a phase C of the power distribution system, wherein,
phase voltages of A phase, B phase and C phase respectively, a flexible grounding device, wherein,
the output voltage of the flexible grounding device, the grounding capacitances of the phase A, the phase B and the phase C of the power distribution system are 3C, the transition resistance of the grounding fault is R,
a phase current of A, B, C phases,
is the ground return current of the neutral point of the distribution system, i.e. the zero sequence current.
With reference to fig. 5, fig. 5 is a schematic diagram of a simplified equivalent circuit for performing ground fault disappearance detection and analysis on a power distribution system according to an embodiment of the present invention; the power distribution system shown in fig. 4 may be equivalent to the circuit diagram shown in fig. 5, with fig. 5 including A, B, C phase voltages of the power distribution system
Output voltage of flexible grounding device
Wherein, assuming that the fault phase is A phase, the impedance to ground of the fault phase which is A phase is equivalent to ZfThe non-faulted phase B, C has a relative ground impedance of ZcThe internal impedance of the power supply of the flexible grounding device is equivalent to Zs，
At a phase current of A, B, C a, the phase current,
is the neutral point grounding loop current of the distribution network. According to fig. 5, the neutral point grounding loop current of the power distribution network can be calculated
Namely, zero sequence current, wherein the calculation formula of the zero sequence current of the neutral point of the power distribution system is as follows:
wherein the content of the first and second substances,
is the output voltage of the flexible grounding means,
being neutral points of the distribution systemZero sequence current of (Z)sIs the internal impedance of the power supply of the flexible grounding device,
for fault phase supply voltage, x is a phase a, b or c, ZfFor fault versus ground impedance, ZcIs the non-fault phase-to-ground impedance.
For example, assuming that the fault phase is phase a, the above equation (b) may be:
in the formula (I), the compound is shown in the specification,
the voltage is output for the flexible grounding means,
for neutral point earth return current, Z, of the distribution networksIs the internal impedance of the power supply of the flexible grounding device,
for a faulted phase A-phase supply voltage, ZfFor fault versus ground impedance, ZcIs the non-fault phase-to-ground impedance.
Further, in conjunction with fig. 5, when the ground fault does not disappear, the formula (a) may become:
wherein the content of the first and second substances,
is the output voltage of the flexible earthing device, ZsIs the internal impedance of the power supply of the flexible grounding device,
for fault phaseSource voltage, x is a phase a, b phase or c phase, ZfFor fault versus ground impedance, ZcIs the non-fault phase-to-ground impedance. The zero sequence impedance Z of the neutral point can be seen from the formula (c)0Output voltage following flexible grounding device
And changes accordingly.
For example, assuming the failed phase is phase a, equation (c) may be:
in the formula (I), the compound is shown in the specification,
is the output voltage of the flexible earthing device, ZsIs the internal impedance of the power supply of the flexible grounding device,
for a faulted phase A-phase supply voltage, ZfFor fault-to-ground impedance, ZcIs the non-fault phase-to-ground impedance.
Further, referring to FIG. 5, when the fault disappears A, B, C is equal relative impedance Zf＝ZcThen, when the ground fault disappears, equation (c) may become:
wherein, ZsInternal impedance of power supply, Z, for flexible earthing meanscIs the non-fault phase-to-ground impedance. Therefore the neutral zero sequence impedance Z0Output voltage independent of flexible grounding device
May be varied.
The invention further utilizes the zero sequence of neutral point measurement when the distribution system is in a non-fault stateImpedance and flexible grounding device power supply
Has no relation with the output of the power distribution system, and when the power distribution system is in a fault state, the zero sequence impedance measured by the neutral point is along with the power supply of the flexible grounding device
Outputting the change rule and detecting that the ground fault disappears. The method has the advantages of simple detection principle, no need of complex direction judgment and stronger engineering applicability.
303. When the maximum value of the variation is smaller than or equal to the setting value of the variation, determining that the ground fault disappears;
304. when the maximum value of the variation is larger than the setting value of the variation, determining that the ground fault does not disappear;
further, the condition of the ground fault is judged by comparing the maximum value of the variation with the setting value of the variation, and specifically, when the maximum value of the variation is less than or equal to the setting value of the variation, the ground fault is determined to disappear; and when the maximum value of the variation is larger than the setting value of the variation, determining that the ground fault does not disappear.
305. And when the ground fault of the power distribution system disappears, controlling the flexible grounding device to stop compensating the ground fault of the power distribution system.
It should be noted that, the content of step 305 is similar to that of step 104 shown in fig. 1, and for avoiding repetition, details are not repeated here, and specific reference may be made to the content of step 104 shown in fig. 1.
The invention provides a method for detecting disappearance of ground faults of a power distribution system, which comprises the following steps: controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, wherein the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground faults; detecting zero sequence impedance of a neutral point of a power distribution system in real time, and determining the maximum value of the variable quantity of the zero sequence impedance; when the maximum value of the variation is less than or equal to the variation setting value, determining that the ground fault disappears; when the maximum value of the variation is larger than the variation setting value, determining that the ground fault does not disappear; and when the ground fault of the power distribution system disappears, controlling the flexible grounding device to stop compensating the ground fault of the power distribution system. The method is beneficial to quickly replacing the traditional grounding mode by the flexible grounding mode, improves the power supply reliability, assists in the consumption of clean energy and the construction of a novel power distribution system, and provides the method for detecting the disappearance of the grounding fault of the flexible grounding system of the power distribution network.
Referring to fig. 6, fig. 6 is a block diagram of a power distribution system ground fault disappearance detection apparatus according to an embodiment of the present invention, where the apparatus shown in fig. 6 includes:
the output voltage adjusting module 601: the flexible grounding device is used for controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, and the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground fault;
zero sequence impedance detection module 602: the zero-sequence impedance detection device is used for detecting the zero-sequence impedance of a neutral point of the power distribution system in real time and determining the maximum value of the variation of the zero-sequence impedance;
the failure disappearance detection module 603: the device is used for determining whether the ground fault of the power distribution system disappears or not according to the maximum variation and a preset variation setting value;
the stop fault compensation module 604: the flexible grounding device is used for controlling the flexible grounding device to stop compensating the ground fault of the power distribution system when the ground fault of the power distribution system disappears;
it should be noted that the functions of each module in the apparatus shown in fig. 6 are similar to the contents of each step in the method shown in fig. 1, and for avoiding repetition, details are not repeated here, and the contents of each step in the method shown in fig. 1 may be referred to specifically.
The invention provides a power distribution system ground fault disappearance detection device, the device includes: an output voltage adjustment module: the flexible grounding device is used for controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, and the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground fault; zero sequence impedance detection module: the method comprises the steps of detecting zero sequence impedance of a neutral point of a power distribution system in real time, and determining the maximum value of variation of the zero sequence impedance; a failure disappearance detection module: the device is used for determining whether the ground fault of the power distribution system disappears or not according to the maximum variable quantity and a preset variable quantity setting value; a stop fault compensation module: and the flexible grounding device is controlled to stop compensating the ground fault of the power distribution system when the ground fault of the power distribution system disappears. The device can sensitively judge that the ground fault disappears without detecting the zero sequence current amplitude and the phase of each outgoing line, solves the problems of complex detection and low reliability of the prior art for the disappearance of the ground fault, has the capability of monitoring the disappearance of the ground fault in real time, has simple detection principle, can realize the automatic exit of compensation output of the flexible grounding device without complex direction judgment, and has strong engineering applicability.
FIG. 7 is a diagram illustrating an internal structure of a computer device in one embodiment. The computer device may specifically be a terminal, and may also be a server. As shown in fig. 7, the computer device includes a processor, a memory, and a network interface connected by a system bus. Wherein the memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program which, when executed by the processor, causes the processor to carry out the above-mentioned method. The internal memory may also have stored therein a computer program which, when executed by the processor, causes the processor to perform the method described above. Those skilled in the art will appreciate that the architecture shown in fig. 7 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.
In an embodiment, a computer device is proposed, comprising a memory and a processor, the memory storing a computer program which, when executed by the processor, causes the processor to perform the steps of the method as shown in fig. 1 or fig. 3.
In an embodiment, a computer-readable storage medium is proposed, in which a computer program is stored which, when being executed by a processor, causes the processor to carry out the steps of the method as shown in fig. 1 or fig. 3.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a non-volatile computer-readable storage medium, and can include the processes of the embodiments of the methods described above when the program is executed. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A power distribution system ground fault disappearance detection method, the method comprising:
controlling a flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, wherein the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground fault;
detecting zero sequence impedance of a neutral point of the power distribution system in real time, and determining the maximum value of the variation of the zero sequence impedance;
determining whether the ground fault of the power distribution system disappears or not according to the maximum variable quantity and a preset variable quantity setting value;
and when the ground fault of the power distribution system disappears, controlling the flexible grounding device to stop compensating the ground fault of the power distribution system.
2. The method of claim 1, wherein the detecting zero sequence impedance of the neutral point of the power distribution system in real time and determining a maximum value of a variation of the zero sequence impedance comprises:
acquiring the maximum value of the zero-sequence impedance and the minimum value of the zero-sequence impedance;
obtaining a zero sequence impedance difference value by using the maximum value of the zero sequence impedance and the minimum value of the zero sequence impedance as a difference;
and taking the zero sequence impedance difference value as the maximum variable value.
3. The method of claim 1, wherein determining whether the ground fault of the power distribution system disappears based on the maximum variation and a preset variation setting comprises:
when the maximum value of the variation is smaller than or equal to the setting value of the variation, determining that the ground fault disappears;
and when the maximum value of the variation is larger than the setting value of the variation, determining that the ground fault does not disappear.
4. The method of claim 1, wherein the flexible grounding device is further configured to detect a ground fault condition of the power distribution system, wherein the ground fault condition includes a ground fault or no fault in the power distribution system, and wherein the controlling the flexible grounding device to adjust the output voltage further comprises:
detecting a ground fault condition of the power distribution system with the flexible grounding device;
when the flexible grounding device detects that the grounding fault condition of the power distribution system is the grounding fault, controlling the flexible grounding device to operate in a full compensation state, wherein the full compensation state is used for completely compensating the grounding fault current of the power distribution system;
recording the compensation time of the flexible grounding device in a full compensation state;
and when the compensation time is equal to a preset time threshold, executing the step of controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value.
5. The method according to claim 1, wherein the zero sequence impedance is calculated as follows:
wherein, the first and the second end of the pipe are connected with each other,
is the output voltage of the flexible grounding device,
is the zero sequence current of the neutral point of the distribution system, | | is the module value of the zero sequence impedance.
6. The method of claim 5, wherein the zero sequence current of the neutral point of the power distribution system is calculated as follows:
wherein the content of the first and second substances,
is the output voltage of the flexible grounding device,
zero sequence current, Z, being the neutral point of the distribution systemsIs the internal impedance of the power supply of the flexible grounding device,
for fault phase supply voltage, x is a phase a, b or c, ZfFor fault versus ground impedance, ZcIs the non-fault phase-to-ground impedance.
7. The method according to claim 6, wherein when the ground fault does not disappear, the zero sequence impedance is calculated as follows:
wherein the content of the first and second substances,
is softOutput voltage of the sexual earthing device, ZsIs the internal impedance of the power supply of the flexible grounding device,
for fault phase supply voltage, x is a phase a, b or c, ZfFor fault versus ground impedance, ZcIs a non-fault phase-to-ground impedance.
8. The method of claim 6, wherein when the ground fault disappears, the zero sequence impedance is calculated as follows:
wherein Z issInternal impedance of power supply, Z, for flexible earthing meanscIs the non-fault phase-to-ground impedance.
9. An electrical distribution system ground fault disappearance detection apparatus, the apparatus comprising:
an output voltage adjustment module: the flexible grounding device is used for controlling the flexible grounding device to adjust the output voltage of the flexible grounding device according to a preset voltage adjustment value, and the flexible grounding device is used for performing ground fault compensation on the power distribution system when the power distribution system has ground fault;
zero sequence impedance detection module: the zero-sequence impedance detection device is used for detecting the zero-sequence impedance of a neutral point of the power distribution system in real time and determining the maximum value of the variation of the zero-sequence impedance;
a failure disappearance detection module: the device is used for determining whether the ground fault of the power distribution system disappears or not according to the maximum variation and a preset variation setting value;
a stop fault compensation module: and the flexible grounding device is used for controlling the flexible grounding device to stop compensating the ground fault of the power distribution system when the ground fault of the power distribution system disappears.
10. A computer device comprising a memory and a processor, characterized in that the memory stores a computer program which, when executed by the processor, causes the processor to carry out the steps of the method according to any one of claims 1 to 8.
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