CN-115792502-B - Ground fault positioning method utilizing temporary and steady state characteristics of PT cable ground current

CN115792502BCN 115792502 BCN115792502 BCN 115792502BCN-115792502-B

Abstract

The application relates to a ground fault positioning method, a device, a server and a storage medium by utilizing the transient and steady state characteristics of PT cable ground current. The method comprises the steps of obtaining a plurality of current setting values corresponding to a plurality of preset points in a power grid circuit, wherein the power grid circuit is a secondary circuit formed by connecting PT cables in a transformer substation with a plurality of secondary windings, determining instantaneous current values of the preset points based on branch parameters of a branch circuit corresponding to the preset points, wherein the branch parameters comprise cable parameters and capacitance parameters, determining whether a ground fault exists in the power grid circuit based on steady-state characteristics corresponding to the current setting values and transient characteristics corresponding to the instantaneous current values of the preset points, and the ground fault is used for representing the cable points which are abnormally connected to the ground in the power grid circuit. By adopting the method, the loss of the power grid load caused by power failure detection can be avoided, and the applicability and accuracy of fault detection are improved.

Inventors

WEN CAIQUAN
OUYANG YUFEI
XIONG XIAOFU
WEI XIN
HUANG YIHUA
LI NING
YAN MAOHUA
LI JUEQIANG
LIU WEI
RONG HAO
QUAN JIEXIONG

Assignees

中国南方电网有限责任公司超高压输电公司梧州局

Dates

Publication Date: 20260512
Application Date: 20221217

Claims (8)

1. A method for locating a ground fault by utilizing temporary and steady-state characteristics of a PT cable ground current, which is characterized by comprising the following steps: The method comprises the steps of obtaining a plurality of current setting values corresponding to a plurality of preset points in a power grid circuit, wherein the power grid circuit is a secondary circuit formed by connecting a PT cable in a transformer substation and a plurality of secondary windings, the PT cable is a wiring cable of a voltage transformer, each preset point belongs to a cable point where a branch circuit in the power grid circuit is located, different preset points belong to cable points where different branch circuits are located, the current setting values are used for representing zero sequence current values leaked when the branch circuit corresponding to the preset point is grounded, and the method comprises the steps of Determining an instantaneous current value of each preset point location based on a branch parameter of a branch circuit where the preset point location corresponds to, wherein the branch parameter comprises a cable parameter and a capacitance parameter; Determining whether a ground fault exists in the power grid circuit or not based on steady-state characteristics corresponding to the current setting values and transient characteristics corresponding to the instantaneous current values of the preset points, wherein the ground fault is used for representing that a cable point abnormally connected to the ground exists in the power grid circuit; the obtaining a plurality of current setting values corresponding to a plurality of preset point positions in the power grid circuit comprises the following steps: acquiring a first zero sequence current value leaked when the PT cable is grounded, a second zero sequence current value leaked when a control outdoor circuit in the power grid circuit is grounded, and a third zero sequence current value leaked when a control indoor circuit in the power grid circuit is grounded; The first zero sequence current value is used as a first current setting value in the plurality of preset points, the second zero sequence current value is used as a second current setting value in the plurality of preset points, and the third zero sequence current value is used as a third current setting value in the plurality of preset points; The branch circuit comprises a branch circuit I which is connected with the plurality of secondary windings, a first branch circuit belonging to a first secondary winding, a second branch circuit belonging to a second secondary winding and a third branch circuit belonging to a third secondary winding, wherein the branch circuit I is a control outdoor circuit in the power grid circuit, and the first branch circuit, the second branch circuit and the third branch circuit are all control indoor circuits in the power grid circuit; The determining whether the branch circuits have the ground fault based on the steady-state characteristics corresponding to the current setting values and the transient characteristics corresponding to the transient current values of the preset points comprises the following steps: if transient amplitude characteristics of the transient current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are smaller than steady-state amplitude characteristics of the third current setting value and are larger than the first current setting value, no ground fault exists in each power grid circuit; if transient amplitude characteristics of the transient current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are all larger than steady-state amplitude characteristics of the second current setting value, a control outdoor circuit in the power grid circuit has a ground fault; If transient amplitude characteristics of the instantaneous current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are larger than steady-state amplitude characteristics of the third current setting value and smaller than steady-state amplitude characteristics of the second current setting value, a ground fault exists in the first branch circuit in the power grid circuit; If transient amplitude characteristics of the instantaneous current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are larger than steady-state amplitude characteristics of the third current setting value and smaller than steady-state amplitude characteristics of the second current setting value, and the instantaneous current values corresponding to the second branch circuit and the third branch circuit are equal and larger than the instantaneous current values corresponding to the first branch circuit, a ground fault exists in the second branch circuit in the power grid circuit; if the transient amplitude characteristics of the transient current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are larger than the steady-state amplitude characteristics of the third current setting value and smaller than the steady-state amplitude characteristics of the second current setting value, and the transient current values corresponding to the first branch circuit and the second branch circuit are equal and smaller than the transient current values corresponding to the third branch circuit, the third branch circuit in the power grid circuit has a ground fault.
2. The method of claim 1, wherein the cable parameters include a cable length and a resistance value corresponding to each of the branch circuits, the capacitance parameters include a capacitance value corresponding to a capacitance in each of the branch circuits, and an angular frequency and an angular velocity generated by the capacitance after the alternating current is communicated to the grid circuit; the determining the instantaneous current value of each preset point location based on the branch parameter of the branch circuit where the preset point location corresponds to comprises: determining instantaneous voltage values corresponding to the preset points based on the input voltage value of alternating current communicated with the power grid circuit and the angular frequency and the angular speed of a capacitor arranged in each branch circuit; And determining the instantaneous current value corresponding to the preset point position of each branch circuit based on the derivative relation among the capacitance value, the cable length and the resistance value in each branch circuit and the instantaneous voltage value corresponding to each preset point position.
3. The method according to claim 1, characterized in that the method further comprises: Determining a first zero sequence voltage instantaneous value when the first branch circuit has a ground fault, a second zero sequence voltage instantaneous value when the second branch circuit has the ground fault and a third zero sequence voltage instantaneous value when the third branch circuit has the ground fault based on branch parameters corresponding to the first branch circuit, the second branch circuit and the third branch circuit; Respectively carrying out time domain analysis on the first zero sequence voltage instantaneous value, the second zero sequence voltage instantaneous value and the third zero sequence voltage instantaneous value to obtain first zero sequence current transient waveform data corresponding to the first zero sequence voltage instantaneous value, second zero sequence current transient waveform data corresponding to the second zero sequence voltage instantaneous value and third zero sequence current transient waveform data corresponding to the third zero sequence voltage instantaneous value; Respectively carrying out wavelet packet decomposition processing, averaging processing and power processing on the first zero-sequence current transient waveform data, the second zero-sequence current transient waveform data and the third zero-sequence current transient waveform data in sequence to obtain first characteristic data corresponding to the first zero-sequence current transient waveform data, second characteristic data corresponding to the second zero-sequence current transient waveform data and third characteristic data corresponding to the third zero-sequence current transient waveform data; And determining whether a ground fault exists in the first branch circuit, the second branch circuit and the third branch circuit based on the magnitudes between the first characteristic data, the second characteristic data and the third characteristic data and corresponding preset threshold values respectively.
4. The method according to claim 3, wherein the sequentially performing wavelet packet decomposition processing, averaging processing and power processing on the first zero-sequence current transient waveform data, the second zero-sequence current transient waveform data and the third zero-sequence current transient waveform data to obtain first feature data corresponding to the first zero-sequence current transient waveform data, second feature data corresponding to the second zero-sequence current transient waveform data and third feature data corresponding to the third zero-sequence current transient waveform data, respectively, includes: Respectively carrying out wavelet packet decomposition processing on each zero-sequence current transient waveform data in sequence, and separating out a first characteristic value, which corresponds to the zero-sequence current transient waveform data and is below 6 times of harmonic waves; centering the first characteristic value of each zero-sequence current transient waveform data by taking a preset period as a unit to obtain a second characteristic value corresponding to each zero-sequence current transient waveform data; Performing averaging treatment on the second characteristic value of each zero-sequence current transient waveform data to obtain a third characteristic value corresponding to each zero-sequence current transient waveform data; And carrying out 4 times of power processing on the third characteristic value of each zero-sequence current transient waveform data to obtain a fourth characteristic value corresponding to each zero-sequence current transient waveform data.
5. A ground fault locating device utilizing temporary and steady state characteristics of a PT cable ground current, the device comprising: the power grid circuit is a secondary circuit formed by connecting a PT cable in a transformer substation and a plurality of secondary windings, the PT cable is a wiring cable of a voltage transformer, each preset point location belongs to a cable point location of a branch circuit in the power grid circuit, and different preset point locations belong to cable point locations of different branch circuits; A current determining unit configured to perform determining an instantaneous current value of each preset point location based on a branch parameter of a branch circuit where each preset point location corresponds to, wherein the branch parameter includes a cable parameter and a capacitance parameter; the fault detection unit is configured to execute a transient characteristic corresponding to the transient current value of each preset point position and based on the steady state characteristic corresponding to the current setting values, and determine whether a ground fault exists in the power grid circuit; The ground fault positioning device utilizing the transient and steady-state characteristics of the PT cable ground current is used for: acquiring a first zero sequence current value leaked when the PT cable is grounded, a second zero sequence current value leaked when a control outdoor circuit in the power grid circuit is grounded, and a third zero sequence current value leaked when a control indoor circuit in the power grid circuit is grounded; The first zero sequence current value is used as a first current setting value in the plurality of preset points, the second zero sequence current value is used as a second current setting value in the plurality of preset points, and the third zero sequence current value is used as a third current setting value in the plurality of preset points; The branch circuit comprises a branch circuit I which is connected with the plurality of secondary windings, a first branch circuit belonging to a first secondary winding, a second branch circuit belonging to a second secondary winding and a third branch circuit belonging to a third secondary winding, wherein the branch circuit I is a control outdoor circuit in the power grid circuit, and the first branch circuit, the second branch circuit and the third branch circuit are all control indoor circuits in the power grid circuit; Determining whether each branch circuit has a ground fault or not based on the steady-state characteristics corresponding to the current setting values and the transient characteristics corresponding to the instantaneous current values of the preset points, wherein the ground fault positioning device using the temporary and steady-state characteristics of the PT cable ground current is used for: if transient amplitude characteristics of the transient current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are smaller than steady-state amplitude characteristics of the third current setting value and are larger than the first current setting value, no ground fault exists in each power grid circuit; if transient amplitude characteristics of the transient current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are all larger than steady-state amplitude characteristics of the second current setting value, a control outdoor circuit in the power grid circuit has a ground fault; If transient amplitude characteristics of the instantaneous current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are larger than steady-state amplitude characteristics of the third current setting value and smaller than steady-state amplitude characteristics of the second current setting value, a ground fault exists in the first branch circuit in the power grid circuit; If transient amplitude characteristics of the instantaneous current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are larger than steady-state amplitude characteristics of the third current setting value and smaller than steady-state amplitude characteristics of the second current setting value, and the instantaneous current values corresponding to the second branch circuit and the third branch circuit are equal and larger than the instantaneous current values corresponding to the first branch circuit, a ground fault exists in the second branch circuit in the power grid circuit; if the transient amplitude characteristics of the transient current values corresponding to the first branch circuit, the second branch circuit and the third branch circuit are larger than the steady-state amplitude characteristics of the third current setting value and smaller than the steady-state amplitude characteristics of the second current setting value, and the transient current values corresponding to the first branch circuit and the second branch circuit are equal and smaller than the transient current values corresponding to the third branch circuit, the third branch circuit in the power grid circuit has a ground fault.
6. A server for a server, which comprises a server and a server, characterized by comprising the following steps: A processor; A memory for storing executable instructions of the processor; Wherein the processor is configured to execute the executable instructions to implement the ground fault localization method utilizing the PT cable ground current transient, steady state feature of any one of claims 1 to 4.
7. A computer readable storage medium having a computer program embodied therein, which when executed by a processor of a server, enables the server to perform the ground fault localization method utilizing the PT cable ground current transient, steady state feature of any one of claims 1 to 4.
8. A computer program product comprising program instructions which, when executed by a processor of a server, enable the server to perform the method of positioning a ground fault using the temporary, steady-state characteristics of a PT cable ground current as claimed in any one of claims 1 to 4.

Description

Ground fault positioning method utilizing temporary and steady state characteristics of PT cable ground current Technical Field The application relates to the technical field of computers, in particular to a ground fault positioning method utilizing the temporary and steady state characteristics of PT cable ground currents, a ground fault positioning device utilizing the temporary and steady state characteristics of PT cable ground currents, a server, a storage medium and a computer program product. Background The voltage transformer (potential transformer, PT) plays two roles in the operation of the power system, namely, the voltage of a tested line is reduced in proportion to provide voltage quantity for the protection, metering and the like of the next stage, and the insulating equipment is isolated from the secondary circuit of the PT. Therefore, in order to prevent the high voltage generated when the system fails from breaking down the insulation equipment, ensure the safety of personnel, equipment and the system, the secondary loop of the PT must ensure reliable and effective grounding. In actual operation, the number of secondary loops of PT is large, the form is complex, the lines are crossed and longer, and the multi-point grounding condition often occurs due to factors such as design, construction, secondary equipment aging, wiring errors and the like. If the fault of the multipoint earthing of the secondary loop of the PT possibly causes the errors of electric energy metering and the indication abnormality of the microcomputer protection device, the relay protection and the safety automatic device act incorrectly, and the like. And the fault of the multipoint earthing of the secondary loop of the PT has great harm to the power station system, the fault can cause the self-produced zero sequence voltage of the microcomputer protection device to deviate, the misjudgment of the zero sequence direction protection can be caused, the cascading failure of the system in a large area is further caused, and the stability of the system is seriously affected. The detection of the multipoint ground fault of the traditional PT secondary circuit requires power failure detection, namely, a direct-current voltage measuring resistor is added to the secondary circuit, or the incorporated resistor determines whether the two-point ground fault occurs or not through measuring the magnitude of current flowing through the resistor. However, when the power is cut to detect the ground fault, the load of the whole power grid is lost, if the power cut time is longer, the load lost by the power grid is larger, and the life influence on the power grid coverage residents is larger. Disclosure of Invention The disclosure provides a ground fault positioning method using transient and steady state characteristics of a PT cable ground current, and a ground fault positioning device, a server, a storage medium and a computer program product using the transient and steady state characteristics of the PT cable ground current, so as to at least solve the problem that a power grid load will be lost when a power failure detection fault is performed on the power grid in the related art. The technical scheme of the present disclosure is as follows: according to a first aspect of an embodiment of the present disclosure, there is provided a ground fault locating method using temporary and steady-state characteristics of a PT cable ground current, including: The method comprises the steps of obtaining a plurality of current setting values corresponding to a plurality of preset points in a power grid circuit, wherein the power grid circuit is a secondary circuit formed by connecting a PT cable in a transformer substation and a plurality of secondary windings, the PT cable is a wiring cable of a voltage transformer, each preset point belongs to a cable point where a branch circuit in the power grid circuit is located, different preset points belong to cable points where different branch circuits are located, the current setting values are used for representing zero sequence current values leaked when the branch circuit corresponding to the preset point is grounded, and the method comprises the steps of Determining an instantaneous current value of each preset point location based on a branch parameter of a branch circuit where the preset point location corresponds to, wherein the branch parameter comprises a cable parameter and a capacitance parameter; And determining whether a ground fault exists in the power grid circuit or not based on steady-state characteristics corresponding to the current setting values and transient characteristics corresponding to the instantaneous current values of the preset points, wherein the ground fault is used for representing that a cable point abnormally connected to the ground exists in the power grid circuit. In an exemplary embodiment, the cable parameters include a cable length and a resistance value corres