Pilot zero sequence protection method, pilot zero sequence protection device and electronic equipment

Abstract

This application belongs to the field of power system relay protection technology, and particularly relates to a longitudinal zero-sequence protection method, a longitudinal zero-sequence protection device, and electronic equipment. The method includes determining the multiphase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak feeder side; generating a weak feeder judgment result based on the multiphase electrical quantities, zero-sequence electrical quantities, and their corresponding weak feeder judgment conditions; detecting the permissive signal issued by the longitudinal zero-sequence protection device on the zero-sequence non-weak feeder side to obtain a signal detection result; and controlling the operating state of the switching equipment on the zero-sequence weak feeder side based on the weak feeder judgment result and the signal detection result.

Description

Technical Field

[0001] The present application belongs to the technical field of power system relay protection, and in particular relates to a pilot zero-sequence protection method, a pilot zero-sequence protection device, and an electronic device. Background Art

[0002] Non-differential pilot protection for power systems mainly includes two types: pilot distance protection and pilot zero-sequence protection. The two have different principles and complementary performances, and are applied cooperatively in power grid fault protection. Among them, the pilot distance protection judges the fault location based on the line impedance measurement principle, and the pilot zero-sequence protection uses the zero-sequence current component generated by the fault to judge the fault state, and has better sensitivity in the scenario of high-resistance ground fault. Under conventional working conditions, the pilot zero-sequence protection and the pilot distance protection share a communication channel, and the weak-infeed side can complete fault protection adaptation relying on the weak-infeed logic matching the pilot distance protection, without the need to separately configure a dedicated pilot zero-sequence weak-infeed protection logic.

[0003] However, in the independent channel scenario in the prior art, the pilot zero-sequence protection lacks an adapted dedicated weak-infeed protection logic, which results in poor flexibility and stability of power system operation protection. Contents of the Invention

[0004] In view of this, the embodiments of the present application provide a pilot zero-sequence protection method, a pilot zero-sequence protection device, and an electronic device, so as to solve the problem of poor flexibility and stability of power system operation protection caused by the existing pilot zero-sequence protection method.

[0005] A first aspect of the embodiments of the present application provides a pilot zero-sequence protection method, which is applied to a pilot zero-sequence protection device on the zero-sequence weak-infeed side, and the method includes: determining the multi-phase electrical quantity and the zero-sequence electrical quantity of the zero-sequence weak-infeed side; generating a weak-infeed determination result based on the multi-phase electrical quantity, the zero-sequence electrical quantity and their respective corresponding weak-infeed determination conditions; detecting the permission signal sent by the pilot zero-sequence protection device on the zero-sequence non-weak-infeed side to obtain a signal detection result; and controlling the action state of the switch device on the zero-sequence weak-infeed side based on the weak-infeed determination result and the signal detection result.

[0006] According to an embodiment of the present application, the pilot zero-sequence protection method further includes: acquiring working state parameters of the pilot zero-sequence protection device; and generating a state determination result based on the working state parameters and the corresponding state determination condition.

[0007] According to an embodiment of the present application, the controlling the action state of the switch device on the zero-sequence weak-infeed side based on the weak-infeed determination result and the signal detection result includes: controlling the action state of the switch device on the zero-sequence weak-infeed side based on the weak-infeed determination result, the signal detection result and the state determination result.

[0008] According to an embodiment of this application, the operating status parameters include the status parameters of each current transformer and the oscillation blocking information and post-acceleration information of the longitudinal zero-sequence protection device.

[0009] According to an embodiment of this application, generating a state determination result based on the working state parameters and the corresponding state determination conditions includes: determining the state determination result as a condition-satisfied result when the state determination conditions are met, wherein satisfying the state determination conditions includes at least one of the following: the state parameters of each current transformer indicate no open circuit, the oscillation blocking information shows that it is not in the oscillation blocking state, and the post-acceleration information shows that it is not in the post-acceleration state.

[0010] According to an embodiment of this application, the multiphase electrical quantities include phase voltages and phase currents, and the zero-sequence electrical quantities include zero-sequence voltages determined based on phase voltages and zero-sequence currents determined based on phase currents.

[0011] According to an embodiment of this application, a weak feeder determination result is generated based on the multiphase electrical quantities and the zero-sequence electrical quantities and their respective weak feeder determination conditions, including: determining the weak feeder determination result as a condition-satisfied result when each phase voltage, each phase current, zero-sequence voltage, and zero-sequence current satisfy their respective weak feeder determination conditions.

[0012] According to an embodiment of this application, the permission signal emitted by the longitudinal zero-sequence protection device on the non-weak feed side of the zero-sequence protection device is detected to obtain a signal detection result, including: detecting whether the independent channel of the longitudinal zero-sequence protection device where the longitudinal zero-sequence protection device is located receives a permission signal emitted by the longitudinal zero-sequence protection device on the non-weak feed side of the zero-sequence protection device, and obtaining the signal detection result.

[0013] According to an embodiment of this application, the operation state of the switching equipment on the zero-sequence weak feeder side is controlled based on the weak feeder determination result and the signal detection result, including: based on the on / off state of the weak feeder trip control word, the operation state of the switching equipment on the zero-sequence weak feeder side is controlled according to the weak feeder determination result and the signal detection result.

[0014] According to an embodiment of this application, based on the enabled / disabled state of the weak feeder trip control word, and according to the weak feeder determination result and the signal detection result, the operating state of the switchgear on the zero-sequence weak feeder side is controlled, including: when the enabled / disabled state is that the weak feeder trip control word is enabled, if the weak feeder determination result is a condition-satisfied result and the signal detection result shows that an allow signal is received from the longitudinal zero-sequence protection device on the zero-sequence non-weak feeder side, the longitudinal zero-sequence protection weak feeder trip operation is controlled, and a trip command is issued to the switchgear on the zero-sequence weak feeder side, wherein the trip command is used to control the operating state of the switchgear.

[0015] According to an embodiment of this application, the longitudinal zero-sequence protection method further includes: when the operation / deactivation state is the weak feeder trip control word exiting, if the weak feeder determination result is a condition-satisfied result and the signal detection result shows that an allow signal is received from the longitudinal zero-sequence protection device on the non-weak feeder side, the longitudinal zero-sequence protection weak feeder trip is controlled to remain closed, and an allow signal is sent to the longitudinal zero-sequence protection device on the non-weak feeder side.

[0016] A second aspect of this application provides a longitudinally coupled zero-sequence protection device, comprising: an electrical quantity determination module for determining multiphase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak-feed side; a weak-feed judgment module for generating a weak-feed judgment result based on the multiphase electrical quantities, the zero-sequence electrical quantities, and their respective corresponding weak-feed judgment conditions; a signal detection module for detecting the permission signal emitted by the longitudinally coupled zero-sequence protection device on the zero-sequence non-weak-feed side and obtaining a signal detection result; and a weak-feed control module for controlling the operating state of the switching equipment on the zero-sequence weak-feed side based on the weak-feed judgment result and the signal detection result.

[0017] A third aspect of this application provides an electronic device, including: one or more processors; and a memory for storing one or more computer programs, wherein the one or more processors execute the one or more computer programs to implement the steps of the method described above.

[0018] A fourth aspect of this application provides a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implement the steps of the above-described method.

[0019] A fifth aspect of this application provides a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the above-described method.

[0020] The beneficial effects of this application embodiment compared with the prior art are as follows: By independently completing the acquisition, calculation, and weak feeder condition determination of multi-phase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak feeder side, and combining the detection results of the zero-sequence non-weak feeder side allowable signal to achieve linkage judgment and control, a dedicated zero-sequence protection logic under an independent channel is constructed, without relying on the weak feeder logic of longitudinal distance protection. This solution accurately identifies the actual grounding fault state of the line through dual verification of the local side condition determination and the fault authorization signal on the opposite side, effectively avoiding unnecessary maloperation of the switchgear on the powerless side, while ensuring reliable tripping of the protection on the strong power supply side and rapid clearing of the line grounding fault, significantly improving the environmental adaptability of the transmission line longitudinal zero-sequence protection and the flexibility and stability of power system operation protection. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart of the longitudinal zero-sequence protection method according to an embodiment of this application is shown; Figure 2 A flowchart of another embodiment of the longitudinal zero-sequence protection method of this application is shown; Figure 3 A flowchart of a longitudinal zero-sequence protection method according to another embodiment of this application is shown; Figure 4 A structural block diagram of the longitudinal zero-sequence protection device according to an embodiment of this application is shown; Figure 5 A block diagram of an electronic device suitable for implementing the above-described method according to an embodiment of this application is shown. Detailed Implementation

[0023] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0025] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0027] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0028] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] In practical power systems, one side of the line may be a weak feeder side. When a fault occurs on this side, the short-circuit current supplied by the weak feeder side is relatively small, and the weak feeder side may not be able to start. The longitudinal zero-sequence protection on the weak feeder side cannot operate quickly and can only operate after the fault on the opposite side has cleared and the current has been redistributed. This results in slow operation and can have a certain impact on the system. Existing technologies for handling weak feeders mainly have the following shortcomings: (1) Under normal circumstances, longitudinal zero-sequence protection and longitudinal distance protection use the same channel, and the weak feeder side does not need to be specially configured with longitudinal zero-sequence protection. However, when the channel used by longitudinal zero-sequence protection is different from the channel used by longitudinal distance protection, its protection logic is independent of longitudinal distance protection. When longitudinal zero-sequence protection is running on an independent channel, the weak feeder logic of longitudinal distance protection cannot be used to achieve the correct operation of the weak feeder side, and a weak feeder processing method needs to be specially designed for the independent channel of longitudinal zero-sequence protection.

[0030] (2) In existing weak feeder protection methods, the tripping strategy of the weak feeder side lacks flexibility. Some schemes involve unconditional tripping of the weak feeder side, which may lead to unnecessary operation of the circuit breaker on the power supply side; some schemes only send back signals from the weak feeder side, which cannot meet the requirements for weak feeder side tripping under certain operating conditions. There is a lack of a method to flexibly configure the weak feeder side tripping strategy through control words.

[0031] (3) The existing weak feeder judgment conditions are relatively simple, usually relying only on low voltage criteria (such as any phase voltage or phase-to-phase voltage being lower than 50% of the rated voltage) or the failure of components in both directions to operate as the judgment basis, lacking precise positioning for the characteristics of longitudinal zero-sequence protection. For example, it does not comprehensively consider the relationship between zero-sequence voltage threshold, three-phase current amplitude and zero-sequence start-up setting, as well as the systematic coordination of blocking conditions such as PT (Potential Transformer) disconnection, CT (Current Transformer) disconnection, and system oscillation.

[0032] Therefore, existing technologies lack a specific protection method suitable for scenarios where longitudinal zero-sequence protection uses an independent channel and achieves tripping or feedback on the weak feeder side through a weak feeder tripping control word. This method can solve the problem that longitudinal zero-sequence protection cannot act quickly when a fault occurs on the weak feeder side, and it can also adapt to scenarios where the longitudinal zero-sequence weak feeder side does not trip but only sends a feedback in the traditional way.

[0033] In view of this, embodiments of this application provide a longitudinal zero-sequence protection method, a longitudinal zero-sequence protection device, and an electronic device to solve the problems of poor flexibility and stability in power system operation protection caused by existing longitudinal zero-sequence protection methods.

[0034] In this embodiment, by independently completing the acquisition, calculation, and weak-feed condition determination of multi-phase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak-feed side, and combining the detection results of the zero-sequence non-weak-feed side allowable signal to achieve linkage judgment and control, a dedicated zero-sequence protection logic under an independent channel is constructed, which does not rely on the weak-feed logic of longitudinal distance protection. This solution accurately identifies the actual grounding fault state of the line through dual verification of the local condition determination and the fault authorization signal on the opposite side, effectively avoiding unnecessary maloperation of the switchgear on the power-free side, while ensuring reliable tripping of the protection on the high-power side and rapid clearing of the line grounding fault, significantly improving the environmental adaptability of the transmission line longitudinal zero-sequence protection and the flexibility and stability of power system operation protection.

[0035] Figure 1 A flowchart of the longitudinal zero-sequence protection method according to an embodiment of this application is shown.

[0036] Please see Figure 1 The longitudinal zero-sequence protection method in this application embodiment can be applied to a longitudinal zero-sequence protection device on the zero-sequence weak feed side. One embodiment of the method may include steps S101 to S104: In step S101, the multiphase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak feed side are determined.

[0037] In step S202, a weak feeder determination result is generated based on the multiphase electrical quantities and zero-sequence electrical quantities and their respective weak feeder determination conditions.

[0038] In step S103, the permission signal issued by the longitudinal zero-sequence protection device on the zero-sequence non-weak feed side is detected to obtain the signal detection result.

[0039] In step S104, the operating state of the switching equipment on the zero-sequence weak feed side is controlled based on the weak feed determination result and the signal detection result.

[0040] Zero-sequence weak feeder side: refers to the line side of a power transmission line in a power system that has no power source or a very small power source capacity and a very weak short-circuit current output capability. When a ground fault occurs on this side of the line, it cannot provide sufficient zero-sequence fault current. Conventional longitudinal zero-sequence protection is prone to failure to operate or false operation, which is the suitable application scenario for this method.

[0041] Multiphase electrical quantities: Specifically refers to the three-phase electrical parameters of the line collected in real time by the zero-sequence weak feeder side longitudinal zero-sequence protection device, including three-phase voltages UA, UB, UC and three-phase currents IA, IB, IC, which are the basic original electrical data for determining the line operating conditions and fault status.

[0042] Zero-sequence electrical quantities are electrical parameters obtained based on multi-phase electrical quantity calculations. They mainly include zero-sequence voltage and zero-sequence current, which can accurately reflect the zero-sequence characteristics of line grounding faults and are the core calculation parameters of zero-sequence protection criteria.

[0043] The authorization signal is an authorized conduction signal sent by the longitudinal zero-sequence protection device configured on the non-weak feeder side of the zero-sequence line to the longitudinal zero-sequence protection device on the opposite side of the zero-sequence line through the communication channel after it has reliably detected a positive-direction ground fault and its own zero-sequence directional element has operated correctly. It is an important cross-side linkage criterion signal for the weak feeder side to determine the validity of the fault and trigger the protection action.

[0044] Switchgear: is a type of power switchgear installed on the zero-sequence weak feeder side of the line to realize the connection, disconnection, fault clearing and isolation of the line. It is the core primary equipment whose controlled action is in this method. Specifically, it may include circuit breakers, load switches, disconnect switches, pole-mounted switches, etc. It completes the state switching of the corresponding operating condition by receiving control commands such as tripping and maintaining operation from the protection device.

[0045] This embodiment discloses a longitudinal zero-sequence protection method applied to the zero-sequence weak feed side, and the specific execution steps are as follows: First, the longitudinal zero-sequence protection device on the weak-feeder side collects multi-phase electrical quantities of the line in real time, namely three-phase voltages UA, UB, UC and three-phase currents IA, IB, IC. The protection device has a built-in Fourier algorithm module that processes the collected raw data of three-phase voltages and currents to accurately calculate the power frequency RMS value and phase parameters of each phase's electrical quantity. Based on this, relying on the principle of the symmetrical component method, the zero-sequence voltage and zero-sequence current of the line are derived through calculation, completing the solution for the zero-sequence electrical quantities. This achieves complete acquisition of multi-phase and zero-sequence electrical quantities, providing data support for subsequent weak-feeder condition determination.

[0046] Secondly, based on the multi-phase electrical quantities and zero-sequence electrical quantities obtained from the data acquisition and calculation, the preset weak feeder judgment conditions are checked one by one, and a comprehensive weak feeder judgment result is generated. In this embodiment, the weak feeder judgment conditions are exclusive criteria adapted to the zero-sequence weak feeder side operating conditions. All judgment conditions must be met simultaneously to determine that this side is in a weak feeder operating condition. If all weak feeder judgment conditions are met, a judgment result that this side is in a zero-sequence weak feeder operating condition is generated, and the next detection step is entered; if any weak feeder judgment condition is not met, this side is determined to be in a normal power supply operating condition, and electrical quantity acquisition and operating condition monitoring continue.

[0047] Then, the signal detection step is executed, continuously monitoring and detecting the permissive signal sent by the longitudinal zero-sequence protection device on the non-weak feeder side of the transmission line in real time, and obtaining the corresponding signal detection results. The non-weak feeder side is the opposite line with a large power supply capacity and strong fault current output capability. Its configured longitudinal zero-sequence protection device can determine the fault direction through its own zero-sequence directional element. If this side successfully receives the permissive signal sent by the non-weak feeder side, it indicates that the non-weak feeder side has accurately determined that a positive-direction ground fault has occurred on the line, and its zero-sequence directional element has operated reliably and correctly. If no permissive signal is received from the non-weak feeder side, it is determined that no valid positive-direction ground fault has been detected on the opposite side, and this side maintains a normal monitoring state without triggering subsequent action logic.

[0048] Finally, combining the aforementioned weak feeder determination results and signal detection results, the operating status of the switchgear associated with the zero-sequence weak feeder side is precisely controlled. When it is determined that this side is in a zero-sequence weak feeder condition and simultaneously successfully receives a permission signal from the non-weak feeder side, the protection device triggers the longitudinal zero-sequence protection weak feeder tripping logic, immediately issuing a tripping command to the circuit breaker on this side to control the switchgear to trip and disconnect the faulty line; if the above dual determination conditions are not met, the switchgear is locked in normal operating condition, and maloperation is prohibited.

[0049] According to the embodiments of this application, by independently completing the acquisition, calculation, and weak-feed condition determination of multi-phase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak-feed side, and combining the detection results of the zero-sequence non-weak-feed side allowable signal to achieve linkage judgment and control, a dedicated zero-sequence protection logic under an independent channel is constructed, which does not rely on the weak-feed logic of longitudinal distance protection. This solution accurately identifies the actual grounding fault state of the line through dual verification of the local side's operating condition determination and the fault authorization signal on the opposite side, effectively avoiding unnecessary maloperation of the switchgear on the power-free side, while ensuring reliable tripping of the protection on the strong power supply side and rapid clearing of the line grounding fault, significantly improving the environmental adaptability of the transmission line longitudinal zero-sequence protection and the flexibility and stability of power system operation protection.

[0050] Figure 2 A flowchart of a longitudinal zero-sequence protection method according to another embodiment of this application is shown.

[0051] According to embodiments of this application, the longitudinal zero-sequence protection method further includes: acquiring the operating status parameters of the longitudinal zero-sequence protection device; generating a status determination result based on the operating status parameters and corresponding status determination conditions; and controlling the operating status of the switching equipment on the zero-sequence weak-feed side based on the weak-feed determination result and the signal detection result.

[0052] The control of the operating state of the switchgear on the zero-sequence weak feeder side based on the weak feeder judgment result and the signal detection result includes: controlling the operating state of the switchgear on the zero-sequence weak feeder side based on the weak feeder judgment result, the signal detection result and the state judgment result, specifically: when the state judgment condition is met, the state judgment result is determined to be the condition-met result, wherein the condition-met state judgment condition includes at least one of the following: the state parameters of each current transformer show no open circuit, the oscillation blocking information shows that it is not in the oscillation blocking state, and the post-acceleration information shows that it is not in the post-acceleration state.

[0053] In one embodiment, operating status parameters are parameters used to characterize the real-time operating conditions, abnormal operating states, and functional activation / deactivation states of the longitudinal zero-sequence protection device. These parameters mainly include key operating parameters such as the device's voltage loop status, current loop status, system oscillation blocking status, and post-fault acceleration function status. They are the core basis for determining whether the protection device meets the conditions for normal operation. Specifically, operating status parameters may include the status parameters of each current transformer, as well as the oscillation blocking information and post-acceleration information of the longitudinal zero-sequence protection device.

[0054] Status determination criteria: These are specific criteria for verifying whether the longitudinal zero-sequence protection device is in normal working condition. They include four core conditions: no PT disconnection, no CT disconnection, the protection device is not in oscillation blocking state, and the protection device is not in post-acceleration state. All of these conditions must be met for the protection device to be determined to be in normal working condition.

[0055] This embodiment, based on the aforementioned longitudinal zero-sequence protection method, adds protection device operating status verification logic and further optimizes the switchgear operation control logic. The specific execution steps are as follows: like Figure 2 As shown, based on the completion of multi-phase electrical quantity and zero-sequence electrical quantity acquisition and calculation and the generation of weak feedback judgment results, the longitudinal zero-sequence protection device on this side synchronously and in real time acquires its own working status parameters, and comprehensively obtains the real-time operating status information of the device's voltage circuit, current circuit, blocking function, and acceleration function.

[0056] Based on preset status judgment conditions, the collected working status parameters are verified in multiple dimensions to generate corresponding status judgment results. In this embodiment, the status judgment conditions include four essential verification conditions, all of which must be met simultaneously: First, the voltage circuit of the protection device is intact, and there is no PT (Power Transmission Unit) open-circuit fault; second, the current circuit of the protection device is normal, and there is no CT (Cross-Circuit Transmission Unit) open-circuit fault; third, the system does not oscillate, and the protection device is not in an oscillation-locked-off state; fourth, there is no need for acceleration after fault reclosing on the line, and the protection device is not in a post-acceleration state. If all four status judgment conditions are met, the protection device is judged to be operating normally and has the conditions for protection action activation; if any one condition is not met, the protection device is judged to have an abnormal operating condition, and the protection action logic is locked.

[0057] Simultaneously, the device continuously monitors the permissive signal transmitted from the zero-sequence non-weak feed side, acquires the signal detection results, and completes the collection of basic fault discrimination information. Ultimately, the action control of the switchgear no longer relies solely on the weak feed judgment result and signal detection result, but combines the weak feed judgment result, signal detection result, and status judgment result into a three-dimensional criterion to achieve precise control of the action status of the zero-sequence weak feed side switchgear.

[0058] The specific control logic is as follows: When the local side determines that it is in a zero-sequence weak feeder condition, successfully receives the non-weak feeder side's allowable signal, and the protection device meets the normal operating conditions of no PT disconnection, no CT disconnection, no oscillation blocking, and no post-acceleration, the protection device will trigger the weak feeder trip logic, issue a trip command to control the operation of circuit breakers, load switches, pole-mounted switches, and other switching equipment, and disconnect the faulty line; if the protection device has any abnormal state, even if the weak feeder condition and the allowable signal conditions on the other side are met, the protection trip action will be blocked to maintain the normal operating state of the switching equipment and avoid protection maloperation or failure to operate under abnormal conditions.

[0059] According to the embodiments of this application, by adding multi-dimensional verification of the working status blocking conditions of four protection devices—PT disconnection, CT disconnection, oscillation blocking, and post-acceleration—to the original weak feeder condition judgment and the detection of the opposite side allowable signal, a weak feeder protection discrimination logic with multi-parameter combination criteria is constructed. Compared with the traditional simple low voltage + forward and reverse component non-operation discrimination method, it can more accurately and comprehensively characterize the zero-sequence weak feeder condition. By linking the triple judgment results to control the operation of the switching equipment, the risk of protection maloperation and failure to operate under special scenarios such as protection device circuit abnormalities, system oscillation, and post-acceleration conditions is effectively avoided. This further improves the discrimination accuracy and operational reliability of the longitudinal zero-sequence weak feeder protection, and significantly optimizes the accuracy of the weak feeder side protection operation and the safety of power grid fault handling.

[0060] According to embodiments of this application, multiphase electrical quantities include phase voltages and phase currents, and zero-sequence electrical quantities include zero-sequence voltages determined based on phase voltages and zero-sequence currents determined based on phase currents.

[0061] According to an embodiment of this application, a weak feeder determination result is generated based on multiphase electrical quantities and zero-sequence electrical quantities and their respective weak feeder determination conditions, including: determining the weak feeder determination result as a condition-satisfied result when each phase voltage, each phase current, zero-sequence voltage, and zero-sequence current satisfy their respective weak feeder determination conditions.

[0062] This embodiment, based on the aforementioned longitudinal zero-sequence protection method, refines the weak feeder judgment logic corresponding to multi-phase electrical quantities and zero-sequence electrical quantities. It completes the weak feeder condition judgment through joint verification using multi-dimensional electrical quantity criteria. The specific execution steps are as follows: First, the longitudinal zero-sequence protection device continuously collects multi-phase electrical quantities and zero-sequence electrical quantities of the line. The multi-phase electrical quantities include three-phase voltages UA, UB, UC and three-phase currents IA, IB, IC. The zero-sequence electrical quantities include the zero-sequence voltage 3U0 calculated based on the voltage of each phase and the zero-sequence current calculated based on the current of each phase, providing complete electrical data support for refined weak feeder judgment.

[0063] Secondly, specific weak infeed judgment conditions are configured for each phase voltage, phase current, zero-sequence voltage, and zero-sequence current. Each type of electrical quantity is precisely verified one by one. Only when all electrical quantities meet the corresponding judgment conditions can the weak infeed judgment result be finally determined as meeting the conditions, and the local side is judged to be in zero-sequence weak infeed condition. The specific judgment details are as follows: First, the voltage weak feeder criterion verification: Detect the voltage of each phase and the phase-to-phase voltage of the line, and determine whether any phase voltage or phase-to-phase voltage is lower than the preset weak feeder low voltage setting value Uweak_set. In this embodiment, Uweak_set is set to 70% of the rated voltage of this line. If the three-phase voltage and all phase-to-phase voltages are not lower than this setting value, it is determined that the weak feeder voltage condition is not met, and this side is identified as a non-weak feeder state. The device returns to the initial state and continues to monitor electrical quantities. If any phase voltage or phase-to-phase voltage is lower than this setting value, the voltage criterion verification is qualified.

[0064] Second, zero-sequence voltage criterion verification: The zero-sequence voltage 3U0 is calculated in real time, and the preset judgment threshold is 1V. When the zero-sequence voltage 3U0 is greater than 1V, it is determined that there is a valid zero-sequence voltage component in the system, which can exclude non-grounding faults without zero-sequence components such as three-phase short circuits, and the zero-sequence voltage criterion verification is qualified; if the zero-sequence voltage 3U0 is not greater than 1V, it is determined that there are no valid grounding fault characteristics, the weak feeder judgment condition is not met, and the device returns to the initial monitoring state.

[0065] Third, three-phase current weak feeder criterion verification: The three-phase currents IA, IB, and IC are collected and detected in real time, and compared with the preset zero-sequence starting current setting I0_start. In this embodiment, I0_start is set to 0.1 times the rated current. When the values ​​of the three-phase currents IA, IB, and IC are all less than this setting, it is determined that there is no effective zero-sequence fault current output on this side, which meets the core characteristics of no power supply and no fault current on the weak feeder side, and the current criterion verification is qualified; if any phase current is greater than or equal to this setting, it is determined that the weak feeder condition characteristics are not met.

[0066] Finally, the device generates a weak feeder judgment result only when all of the above voltage criteria, zero-sequence voltage criteria, and three-phase current criteria are simultaneously satisfied. This confirms that the local side is in a stable zero-sequence weak feeder condition and can proceed to the subsequent process of detecting the opposite side's allowable signal, verifying the status of the protection device, and controlling the operation of the switching equipment. If any electrical quantity criterion is not satisfied, the weak feeder protection logic will not be triggered, and the device will continue to maintain a normal monitoring state.

[0067] According to the embodiments of this application, by clearly distinguishing the judgment dimensions of multi-phase electrical quantities and zero-sequence electrical quantities, and setting exclusive weak feeder judgment conditions for phase voltage, phase-to-phase voltage, zero-sequence voltage, and three-phase current, a refined and multi-dimensional combination of weak feeder electrical quantity judgment criteria is constructed. This method is specifically adapted to the application scenario of independent channel for longitudinal zero-sequence protection, without relying on the weak feeder logic of longitudinal distance protection, filling the technical gap in accurate protection judgment of the weak feeder side in independent channel scenarios. Compared with the traditional simple judgment method of "low voltage + no operation of components in both directions", this method combines multi-level electrical quantity judgment criteria such as low voltage threshold, zero-sequence voltage threshold, and weak current threshold, which can accurately characterize the electrical operating characteristics of the zero-sequence weak feeder side, effectively distinguish between weak feeder operating conditions, normal operating conditions, and non-grounding fault operating conditions, greatly improving the accuracy and scenario adaptability of weak feeder operating condition judgment, and providing a reliable pre-judgment basis for the accurate control of subsequent protection actions.

[0068] According to an embodiment of this application, the permission signal emitted by the longitudinal zero-sequence protection device on the non-weak feed side of the zero-sequence protection device is detected to obtain a signal detection result, including: detecting whether the independent channel of the longitudinal zero-sequence protection device where the longitudinal zero-sequence protection device is located receives a permission signal emitted by the longitudinal zero-sequence protection device on the non-weak feed side of the zero-sequence protection device, and obtaining a signal detection result.

[0069] The independent channel for longitudinal zero-sequence protection is a dedicated communication channel that is independent of the longitudinal distance protection channel and is used to transmit longitudinal zero-sequence protection interactive signals. This channel only carries zero-sequence protection-related interactive commands, and the signal transmission is independent and free from channel coupling interference. It is the core carrier for realizing the independent logic operation of zero-sequence protection.

[0070] Signal stabilization confirmation: This is a validity verification mechanism for the allowed signal settings on the other side. It filters out transient interference signals through a continuous duration threshold to avoid signal misjudgment caused by channel jitter and transient interference, thus ensuring the accuracy of protection signal identification.

[0071] Based on the aforementioned weak feeder condition determination, this embodiment refines the detection logic for the zero-sequence non-weak feeder side allowable signal, and completes accurate signal detection based on the independent channel of the longitudinal zero-sequence protection. The specific execution steps are as follows: After determining that the local side is in a zero-sequence weak feed condition through multi-dimensional electrical quantity criteria, the longitudinal zero-sequence protection device starts the independent channel signal detection process, which monitors the signal only for the dedicated independent channel of the longitudinal zero-sequence protection. It does not occupy or rely on the longitudinal distance protection channel throughout the process, thus realizing the independent acquisition and discrimination of the zero-sequence protection signal.

[0072] The protection device monitors the signal transmission status on the independent channel in real time and continuously collects the permission signal sent by the zero-sequence non-weak feeder longitudinal zero-sequence protection device. To avoid misjudgments caused by factors such as instantaneous interference, signal jitter, and pulse noise, this embodiment adds anti-jitter confirmation logic to the permission signal, setting the effective signal determination duration threshold to 5ms (or other durations). Only when the duration of the permission signal continuously received on the independent channel from the non-weak feeder exceeds 5ms is the permission signal deemed valid, and a detection result of receiving a valid permission signal is generated.

[0073] If a valid permission signal is detected in the independent channel, it indicates that the zero-sequence non-weak feeder side longitudinal zero-sequence protection device has reliably determined that a positive ground fault has occurred on the line, and the zero-sequence directional element on the power supply side has acted accurately and correctly. At this time, the subsequent switchgear operation control process is entered, and the protection action logic is executed in combination with the weak feeder determination result and the device status determination result.

[0074] If no permission signal is detected in the independent channel, or only an invalid signal that is momentary, intermittent and lasts for less than 5ms is received, it is determined that no valid permission signal has been received, and a detection result of no valid permission signal is generated. The protection device maintains normal monitoring status, does not trigger tripping action logic, and continues to monitor the independent channel signal and line electrical quantities in real time.

[0075] According to the embodiments of this application, the detection and discrimination of the opposite-side allowable signal are completed by relying on the dedicated independent channel of the longitudinal zero-sequence protection, which completely realizes the independent operation of the zero-sequence protection signal interaction logic. It does not require the channel resources and weak feeder logic of the longitudinal distance protection, and fully guarantees the independence and integrity of the zero-sequence protection logic under the independent channel. At the same time, by setting a continuous signal anti-jitter verification mechanism, false signals generated by channel jitter and electromagnetic interference are effectively filtered out, eliminating the protection misjudgment and maloperation caused by instantaneous interference. This further improves the accuracy and operational stability of the longitudinal zero-sequence protection signal detection on the weak feeder side, and adapts to the various line fault protection needs in the independent channel scenario.

[0076] According to an embodiment of this application, the operating state of the switchgear on the zero-sequence weak feeder side is controlled based on the weak feeder determination result and the signal detection result, including: based on the on / off state of the weak feeder trip control word, the operating state of the switchgear on the zero-sequence weak feeder side is controlled according to the weak feeder determination result and the signal detection result.

[0077] Weak feeder trip control word: This is a control indicator used in the longitudinal zero-sequence protection device to switch the operation mode of weak feeder protection. By configuring the two states of this control word, the fault handling logic of the zero-sequence weak feeder side can be flexibly switched to adapt to the protection needs of different power grid operation modes.

[0078] This embodiment, based on the weak feeder determination result and the detection result of the opposite side allow signal, introduces the on / off state of the weak feeder trip control word as the basis for regulation, so as to realize differentiated and refined control of the operating state of the zero-sequence weak feeder side switchgear. The specific execution steps are as follows: After the protection device completes the line electrical quantity acquisition and calculation, weak feeder condition judgment, and independent channel permission signal detection, and obtains reliable weak feeder judgment and signal detection results, the device reads the current state of the local weak feeder trip control word in real time. The device uses the enabled / disabled state of the weak feeder trip control word as an important auxiliary control criterion, which, together with the weak feeder judgment result and signal detection result, constitutes a comprehensive control logic to achieve differentiated control of the operating state of the zero-sequence weak feeder side switchgear. This embodiment introduces the state parameter of the weak feeder trip control word, changing the traditional single mode of relying solely on fixed logic to execute protection actions. It can adapt to different protection operation strategies based on the preset control word configuration state of the protection device.

[0079] This embodiment is not limited to fixed tripping or blocking logic, but rather matches the corresponding protection action strategy based on different enabling and disabling states of the weak feeder tripping control word. Combined with the confirmed weak feeder operating conditions and the valid opposite side permission signal, it adaptively adjusts the action control mode of the weak feeder side switchgear to realize configurable operation of the protection logic and adapt to the diverse operating scenarios of the power grid.

[0080] By flexibly configuring the control word state, it can be adapted to the fault handling needs under different line operation modes, avoiding the problem of poor adaptability of a single protection logic, and providing basic logical support for subsequent fine differentiation of protection action behavior under different operating conditions.

[0081] According to embodiments of this application, by introducing the on / off state of the weak feeder tripping control word into the switching equipment operation control based on the weak feeder judgment result and signal detection result, a configurable and non-singular weak feeder protection control logic is constructed, which does not rely on the weak feeder logic of longitudinal distance protection. Through multi-dimensional condition comprehensive decision-making, the shortcomings of the traditional fixed weak feeder protection operation logic are changed, which can adapt to various operating conditions of transmission lines, improve the adaptability and operational flexibility of longitudinal zero-sequence weak feeder protection, and provide a reliable infrastructure for the subsequent refinement of refined and differentiated weak feeder protection operation strategies.

[0082] According to an embodiment of this application, based on the enabled / disabled state of the weak feeder trip control word, and according to the weak feeder determination result and signal detection result, the operating state of the switchgear on the zero-sequence weak feeder side is controlled, including: when the enabled / disabled state is that the weak feeder trip control word is enabled, if the weak feeder determination result is a condition met and the signal detection result shows that an allow signal is received from the longitudinal zero-sequence protection device on the zero-sequence non-weak feeder side, the longitudinal zero-sequence protection weak feeder trip action is controlled, and a trip command is issued to the switchgear on the zero-sequence weak feeder side. The trip command is used to control the operating state of the switchgear.

[0083] Action confirmation delay T1: A fixed delay anti-jitter time threshold configured for weak feeder tripping action, typically 10~20ms, used to filter out false fault conditions caused by instantaneous electrical disturbances and transient interference in the channel, ensuring that the protection action judgment is continuously stable and effective, and improving the anti-maloperation capability of the weak feeder tripping logic.

[0084] This embodiment, based on the aforementioned configurable weak feeder protection control logic, further refines the protection action execution process under the condition that the weak feeder trip control word is enabled, achieving precise trip control when the weak feeder judgment condition and the opposite side permission signal condition are met. The specific execution steps are as follows: When the weak feeder trip control word is in the active state, the protection device continuously verifies the local weak feeder condition judgment result and the signal detection result of the independent channel. If the device determines that the local weak feeder judgment result meets the conditions, that is, all the electrical quantities on this side meet the weak feeder condition criteria, and the signal detection result shows that the device stably receives the permission signal sent by the zero-sequence non-weak feeder side longitudinal zero-sequence protection device on the independent channel of the longitudinal zero-sequence protection, then it enters the weak feeder trip operation preparation logic.

[0085] To avoid protection maloperation caused by transient interference and short-term state fluctuations, this scheme adds a fixed delay confirmation mechanism. Under the premise that the weak feeder judgment condition and the opposite side's allowable signal are simultaneously and continuously met, a stable confirmation is achieved after a typical delay T1 of 10~20ms. After the delay ends and all criteria remain valid, the protection device officially triggers the longitudinal zero-sequence protection weak feeder tripping logic, issuing trip commands to the circuit breakers, load switches, disconnect switches, pole-mounted switches, and other switching equipment configured on the zero-sequence weak feeder side. The trip commands precisely control the opening action of the switching equipment, completing the isolation of the faulty line.

[0086] At the same time, the protection device on this side continuously sends an allow signal to the zero-sequence non-weak feeder side or maintains the state of the sent allow signal through the independent channel of the longitudinal zero-sequence protection, so as to realize the interaction and coordination of the protection signals on both sides of the line, ensure that the protection on the strong power supply side of the opposite side can reliably and stably complete the tripping action, and realize the reliable clearing of the ground fault of the entire line.

[0087] According to the embodiments of this application, by linking the weak feeder judgment result with the opposite side's allow signal when the weak feeder trip control word is activated, and cooperating with the delayed confirmation mechanism to execute the weak feeder trip action, the active trip control when the fault condition on the weak feeder side is stable and effective is accurately realized. The delayed confirmation mechanism can effectively filter out false criteria caused by instantaneous electrical disturbances and transient interference in the channel, significantly improving the anti-maloperation performance and operational reliability of the weak feeder trip logic. At the same time, through the linkage method of synchronously sending allow signals from this side to the opposite side, the coordinated action of the protection on both sides of the line is realized. While ensuring reliable fault clearing on the weak feeder side, it further ensures stable tripping of the protection on the high power supply side, comprehensively improving the integrity and reliability of longitudinal zero-sequence protection fault handling in independent channel scenarios.

[0088] According to an embodiment of this application, the longitudinal zero-sequence protection method further includes: when the weak feeder trip control word is exited in the activation / deactivation state, if the weak feeder determination result is a condition met and the signal detection result shows that an allow signal is received from the longitudinal zero-sequence protection device on the non-weak feeder side, the longitudinal zero-sequence protection weak feeder trip is controlled to remain closed, and an allow signal is sent to the longitudinal zero-sequence protection device on the non-weak feeder side.

[0089] Permission signal extension: refers to extending the duration of the permission signal sent from this side to the other side. In this embodiment, the typical extension duration is 100~150ms, which is used to ensure that the protection device on the other side can stably and reliably acquire the valid permission signal and avoid the protection failure due to instantaneous signal loss.

[0090] Reset Delay: To protect the logic recovery delay after the lockout is released, this embodiment sets it to 200ms. After the lockout conditions such as PT disconnection, CT disconnection, oscillation lockout, and post-acceleration are eliminated, the weak feedback judgment logic is reopened only after the reset delay ends, so as to prevent the protection logic from being frequently turned on and off due to instantaneous fluctuations in the operating conditions.

[0091] This embodiment refines the protection operation logic under the condition of the weak feeder trip control word being out of operation. Under the premise that all weak feeder judgment conditions are met and the independent channel effectively receives the allow signal from the other side, a differentiated protection strategy adapted to the control word's on state is executed. The specific execution steps are as follows: When the weak feeder trip control word is in the off state, the protection device continuously monitors the weak feeder condition judgment result and the independent channel signal status on this side. If all weak feeder judgment conditions on this side are continuously met, and the independent channel of the longitudinal zero-sequence protection stably detects a valid allow signal sent by the zero-sequence non-weak feeder side, the weak feeder trip logic of the longitudinal zero-sequence protection on this side remains inactive, and all switching equipment such as circuit breakers, load switches, disconnectors, and pole-mounted switches maintain the closed operation state, without performing fault tripping operations.

[0092] Simultaneously, the local protection device immediately sends an allow signal back to the zero-sequence non-weak feeder protection device through the independent channel of the longitudinal zero-sequence protection. This outgoing allow signal is then broadened; in this embodiment, the signal broadening duration is set to 100-150ms to ensure that the opposite protection can continuously and stably obtain valid allow commands. Because the power supply to the weak feeder is extremely weak, the zero-sequence directional element has difficulty accurately determining the fault direction. The local device uses the broadened allow signal to complete the reverse logic confirmation using the positive fault result already determined by the opposite side, assisting the strong power supply side protection in meeting the complete tripping condition of "positive fault determination established on this side + receipt of allow signal from the opposite side".

[0093] In this embodiment, four device abnormality blocking conditions have the highest judgment priority: PT disconnection, CT disconnection, oscillation blocking, and post-acceleration state. Throughout the weak feeder judgment and signal interaction process, once any blocking condition is met, regardless of whether the weak feeder electrical criteria such as voltage, current, and zero-sequence component are satisfied, the device immediately exits the weak feeder judgment logic and directly blocks the entire weak feeder protection function, preventing protection misjudgments and malfunctions under device abnormalities, system oscillations, and post-acceleration conditions.

[0094] Once the abnormal operating conditions that caused the logic blocking are completely eliminated, the protection device waits for a 200ms reset delay. After the electrical conditions of the line and the operating status of the device are completely stable, the weak feeder judgment logic is reopened, restoring the normal weak feeder condition monitoring and fault identification functions, ensuring the smoothness and safety of the protection logic switching on and off.

[0095] According to the embodiments of this application, by adopting differentiated control logic of "no tripping on this side, feedback assisting tripping on the opposite side" when the weak feeder tripping control word is removed, it fully adapts to the operating condition characteristics of the weak feeder side without power supply, which cannot reliably determine the direction of zero-sequence faults. This effectively avoids unnecessary tripping operations of the switchgear on the powerless side, reducing equipment operation losses and unnecessary disturbances to the power grid. Through the design of allowing signal expansion of 100~150ms, the stability of the protection signal acquisition on the opposite non-weak feeder side is greatly improved, ensuring that the faulty line is reliably disconnected by the strong power supply side, achieving complete fault clearance. At the same time, by setting the highest priority of four blocking conditions and a 200ms reset delay mechanism, the risk of protection maloperation under special operating conditions such as device circuit abnormalities, system oscillations, and post-acceleration is effectively avoided, ensuring that the weak feeder protection only operates when both the system and the device are normal. This further improves the operational stability, operating condition adaptability, and fault handling reliability of the independent channel longitudinal zero-sequence weak feeder protection.

[0096] Figure 3 A flowchart of a longitudinal zero-sequence protection method according to another embodiment of this application is shown.

[0097] This embodiment combines Figure 3 The overall process of the longitudinal zero-sequence protection in this application is described. After the protection method is started, the weak feed judgment condition detection is first performed to determine whether the weak feed judgment condition and the state judgment condition are all satisfied; if the judgment result is not, it returns directly and continues to monitor in a loop.

[0098] If both the weak feeder detection condition and the status detection condition are met, the process proceeds to the channel permission signal detection step to determine if a permission signal from the other side with a duration greater than 5ms has been received. If no permission signal meeting the duration requirement is received, the process returns directly. Upon receiving a valid permission signal from the other side, the weak feeder control word WeakTrip_En is checked for activation or deactivation. If the weak feeder control word is in the activated state, a weak feeder trip is executed; if the weak feeder control word is in the deactivated state, the weak feeder trip does not occur, and a feedback operation is performed. After completing the above branch processing, the process returns to the next round of loop detection.

[0099] Figure 4 A structural block diagram of a longitudinal zero-sequence protection device according to an embodiment of this application is shown.

[0100] like Figure 4 As shown, the longitudinal zero-sequence protection device 400 includes an electrical quantity determination module 410, a weak feeder determination module 420, a signal detection module 430, and a weak feeder control module 440.

[0101] The electrical quantity determination module 410 is used to determine the multiphase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak feeder side.

[0102] The weak feeder determination module 420 is used to generate a weak feeder determination result based on multiphase electrical quantities and zero-sequence electrical quantities and their corresponding weak feeder determination conditions.

[0103] The signal detection module 430 is used to detect the permission signal issued by the longitudinal zero-sequence protection device on the zero-sequence non-weak feed side and obtain the signal detection result.

[0104] The weak feed control module 440 is used to control the operating state of the switching equipment on the zero-sequence weak feed side based on the weak feed determination result and the signal detection result.

[0105] According to the embodiments of this application, by independently completing the acquisition, calculation, and weak-feed condition determination of multi-phase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak-feed side, and combining the detection results of the zero-sequence non-weak-feed side allowable signal to achieve linkage judgment and control, a dedicated zero-sequence protection logic under an independent channel is constructed, which does not rely on the weak-feed logic of longitudinal distance protection. This solution accurately identifies the actual grounding fault state of the line through dual verification of the local side's operating condition determination and the fault authorization signal on the opposite side, effectively avoiding unnecessary maloperation of the switchgear on the power-free side, while ensuring reliable tripping of the protection on the strong power supply side and rapid clearing of the line grounding fault, significantly improving the environmental adaptability of the transmission line longitudinal zero-sequence protection and the flexibility and stability of power system operation protection.

[0106] According to an embodiment of this application, the longitudinal zero-sequence protection device further includes an acquisition module and a status determination module.

[0107] The acquisition module is used to acquire the operating status parameters of the longitudinal zero-sequence protection device.

[0108] The status determination module is used to generate status determination results based on the working status parameters and the corresponding status determination conditions.

[0109] According to an embodiment of this application, the weak feed control module includes a weak feed control unit.

[0110] The weak feed control unit is used to control the operating status of the switching equipment on the zero-sequence weak feed side based on the weak feed determination result, signal detection result, and status determination result.

[0111] According to embodiments of this application, the operating status parameters include the status parameters of each current transformer and the oscillation blocking information and post-acceleration information of the longitudinal zero-sequence protection device.

[0112] According to an embodiment of this application, the state determination module includes a result determination unit.

[0113] The result determination unit is used to determine the state determination result as a condition-satisfied result when the state determination conditions are met. The condition-satisfied result includes at least one of the following: the state parameters of each transformer are characterized as having no open circuits, the oscillation blocking information is not in the oscillation blocking state, and the post-acceleration information is not in the post-acceleration state.

[0114] According to embodiments of this application, multiphase electrical quantities include phase voltages and phase currents, and zero-sequence electrical quantities include zero-sequence voltages determined based on phase voltages and zero-sequence currents determined based on phase currents.

[0115] According to an embodiment of this application, the weak feed determination module includes a weak feed determination unit.

[0116] The weak feeder determination unit is used to determine the weak feeder determination result as a condition-satisfied result when each phase voltage, each phase current, zero-sequence voltage, and zero-sequence current meet their respective weak feeder determination conditions.

[0117] According to an embodiment of this application, the signal detection module includes a signal detection unit.

[0118] The signal detection unit is used to detect whether the independent channel of the longitudinal zero-sequence protection device where the longitudinal zero-sequence protection device is located receives an allow signal from the longitudinal zero-sequence protection device on the non-weak feed side of the zero-sequence protection device, and obtain the signal detection result.

[0119] According to an embodiment of this application, the weak feed control module includes a weak feed control submodule.

[0120] The weak feed control submodule is used to control the operation status of the switching equipment on the zero-sequence weak feed side based on the on / off status of the weak feed trip control word, the weak feed determination result, and the signal detection result.

[0121] According to an embodiment of this application, the weak feed control submodule includes a first weak feed control unit.

[0122] The first weak feeder control unit is used to control the longitudinal zero-sequence protection weak feeder tripping action when the weak feeder tripping control word is enabled in the enabled / disabled state. If the weak feeder determination result meets the condition and the signal detection result shows that the allow signal issued by the longitudinal zero-sequence protection device on the zero-sequence non-weak feeder side has been received, the unit will also issue a tripping command to the switchgear on the zero-sequence weak feeder side. The tripping command is used to control the operation status of the switchgear.

[0123] According to an embodiment of this application, the weak feed control submodule further includes a second weak feed control unit.

[0124] The second weak feeder control unit is used to control the longitudinal zero-sequence protection weak feeder trip to remain closed when the weak feeder trip control word is exited in the enabled / disabled state, if the weak feeder determination result is a condition met and the signal detection result shows that an allow signal has been received from the longitudinal zero-sequence protection device on the non-weak feeder side, and to send an allow signal to the longitudinal zero-sequence protection device on the non-weak feeder side.

[0125] According to embodiments of this application, any multiple modules among the electrical quantity determination module 410, weak feed determination module 420, signal detection module 430, and weak feed control module 440 can be combined into one module, or any one of these modules can be split into multiple modules. Alternatively, at least some of the functions of one or more of these modules can be combined with at least some of the functions of other modules and implemented in one module. According to embodiments of this application, at least one of the electrical quantity determination module 410, weak feed determination module 420, signal detection module 430, and weak feed control module 440 can be at least partially implemented as hardware circuits, such as field-programmable gate arrays, programmable logic arrays, systems-on-a-chip, systems-on-a-substrate, systems-on-package, application-specific integrated circuits, or any other reasonable means of integrating or packaging circuits, or implemented in software, hardware, and firmware, or in any appropriate combination of any of these three implementation methods. Alternatively, at least one of the electrical quantity determination module 410, weak feed judgment module 420, signal detection module 430, and weak feed control module 440 can be at least partially implemented as a computer program module, which can perform corresponding functions when the computer program module is run.

[0126] Figure 5 A block diagram of an electronic device suitable for implementing the above-described method according to an embodiment of this application is shown.

[0127] like Figure 5 As shown, an electronic device 500 according to an embodiment of this application includes a processor 501, which can perform various appropriate actions and processes according to a program stored in a read-only memory 502 or a program loaded from a storage portion 508 into a random access memory 503. The processor 501 may include, for example, a general-purpose microprocessor, an instruction set processor and / or an associated chipset and / or a dedicated microprocessor. The processor 501 may also include onboard memory for caching purposes. The processor 501 may include a single processing unit or multiple processing units for executing different steps of the method flow according to an embodiment of this application.

[0128] Random access memory 503 stores various programs and data required for the operation of electronic device 500. Processor 501, read-only memory 502, and random access memory 503 are interconnected via bus 504. Processor 501 executes various steps of the method flow according to embodiments of this application by executing programs in read-only memory 502 and / or random access memory 503. It should be noted that the programs may also be stored in one or more memories other than read-only memory 502 and random access memory 503. Processor 501 may also execute various steps of the method flow according to embodiments of this application by executing programs stored in said one or more memories.

[0129] According to embodiments of this application, the electronic device 500 may further include an input / output interface 505, which is also connected to a bus 504. The electronic device 500 may also include one or more of the following components connected to the input / output interface 505: an input section 506 including a keyboard, mouse, etc.; an output section 507 including a cathode ray tube, liquid crystal display, etc., and a speaker, etc.; a storage section 508 including a hard disk, etc.; and a communication section 509 including a network interface card, such as a local area network card, modem, etc. The communication section 509 performs communication processing via a network such as the Internet. A drive 510 is also connected to the input / output interface 505 as needed. A removable medium 511, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 510 as needed so that computer programs read from it can be installed into the storage section 508 as needed.

[0130] Embodiments of this application also provide a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of this application.

[0131] According to embodiments of this application, the computer-readable storage medium can be a non-volatile computer-readable storage medium, such as including but not limited to: portable computer disks, hard disks, random access memory, read-only memory, erasable programmable read-only memory, portable compact disk read-only memory, optical storage devices, magnetic storage devices, or any suitable combination thereof. In embodiments of this application, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of this application, the computer-readable storage medium may include the read-only memory 502, and / or random access memory 503, and / or one or more memories other than read-only memory 502 and random access memory 503 described above.

[0132] Embodiments of this application also include a computer program product comprising a computer program containing program code for performing the methods shown in the flowchart. When the computer program product is run on a computer system, the program code is used to cause the computer system to implement the methods provided in the embodiments of this application.

[0133] In one embodiment, the computer program may rely on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may also be transmitted and distributed in the form of signals over a network medium, and may be downloaded and installed via the communication section 509, and / or installed from a removable medium 511. The program code contained in the computer program can be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination thereof.

[0134] In embodiments of this application, the computer program can be downloaded and installed from a network via communication section 509, and / or installed from removable medium 511. When the computer program is executed by processor 501, it performs the functions defined in the system of this application embodiment. According to embodiments of this application, the systems, devices, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0135] According to embodiments of this application, program code for executing the computer programs provided in the embodiments of this application can be written in any combination of one or more programming languages. Specifically, these computational programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. The program code can be executed entirely on the user's computing device, partially on the user's device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0136] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0137] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

Claims

1. A longitudinal zero-sequence protection method, applied to a longitudinal zero-sequence protection device on the zero-sequence weak feed side, characterized in that, include: Determine the multiphase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak feeder side; Based on the multiphase electrical quantities and the zero-sequence electrical quantities, as well as their respective weak feeder determination conditions, a weak feeder determination result is generated; The permissive signal emitted by the longitudinal zero-sequence protection device on the non-weak feed side of the zero-sequence is detected, and the signal detection result is obtained. Based on the weak feed determination result and the signal detection result, the operation state of the switching equipment on the zero-sequence weak feed side is controlled.

2. The longitudinal zero-sequence protection method according to claim 1, characterized in that, Also includes: Obtain the operating status parameters of the longitudinal zero-sequence protection device; Based on the working status parameters and the corresponding status determination conditions, a status determination result is generated; The control of the operating state of the switching equipment on the zero-sequence weak feed side based on the weak feed determination result and the signal detection result includes: Based on the weak feed determination result, the signal detection result, and the state determination result, the operation state of the switching equipment on the zero-sequence weak feed side is controlled.

3. The longitudinal zero-sequence protection method according to claim 2, characterized in that, The operating status parameters include the status parameters of each current transformer and the oscillation blocking information and post-acceleration information of the longitudinal zero-sequence protection device. The step of generating a state determination result based on the working state parameters and the corresponding state determination conditions includes: If the state determination conditions are met, the state determination result is determined to be a condition-satisfied result. The condition for satisfying the state determination conditions includes at least one of the following: the state parameters of each transformer show no open circuit, the oscillation blocking information shows that it is not in the oscillation blocking state, and the post-acceleration information shows that it is not in the post-acceleration state.

4. The longitudinal zero-sequence protection method according to claim 1, characterized in that, The multiphase electrical quantities include the voltage and current of each phase, and the zero-sequence electrical quantities include the zero-sequence voltage determined based on the voltage of each phase and the zero-sequence current determined based on the current of each phase. The weak feeder determination result is generated based on the multiphase electrical quantities, the zero-sequence electrical quantities, and their respective weak feeder determination conditions, including: If each phase voltage, each phase current, zero-sequence voltage, and zero-sequence current satisfy their respective weak feeder determination conditions, the weak feeder determination result is determined to be a condition-satisfied result.

5. The longitudinal zero-sequence protection method according to claim 1, characterized in that, The permissive signal emitted by the longitudinal zero-sequence protection device on the non-weak feed side of the zero-sequence circuit is detected, and the signal detection results are obtained, including: The signal detection result is obtained by detecting whether the independent channel of the longitudinal zero-sequence protection device where the longitudinal zero-sequence protection device is located receives an allow signal from the longitudinal zero-sequence non-weak feed side.

6. The longitudinal zero-sequence protection method according to claim 1, characterized in that, Based on the weak feed determination result and the signal detection result, the operating state of the switching equipment on the zero-sequence weak feed side is controlled, including: Based on the enabled / disabled status of the weak feeder trip control word, the operating status of the switching equipment on the zero-sequence weak feeder side is controlled according to the weak feeder determination result and the signal detection result.

7. The longitudinal zero-sequence protection method according to claim 6, characterized in that, Based on the enabled / disabled status of the weak feeder trip control word, and according to the weak feeder determination result and the signal detection result, the operating status of the switching equipment on the zero-sequence weak feeder side is controlled, including: When the weak feeder trip control word is enabled in the enabled / disabled state, if the weak feeder determination result is a condition met and the signal detection result shows that an allow signal is received from the longitudinal zero-sequence protection device on the zero-sequence non-weak feeder side, the longitudinal zero-sequence protection weak feeder trip action is controlled, and a trip command is sent to the switchgear on the zero-sequence weak feeder side. The trip command is used to control the operation state of the switchgear.

8. The longitudinal zero-sequence protection method according to claim 7, characterized in that, Also includes: When the weak feeder trip control word is exited in the activation / deactivation state, if the weak feeder determination result is a condition met and the signal detection result shows that an allow signal has been received from the longitudinal zero-sequence protection device on the non-weak feeder side, the longitudinal zero-sequence protection weak feeder trip is controlled to remain closed, and an allow signal is sent to the longitudinal zero-sequence protection device on the non-weak feeder side.

9. A longitudinal zero-sequence protection device, characterized in that, include: The electrical quantity determination module is used to determine the multiphase electrical quantities and zero-sequence electrical quantities on the zero-sequence weak feeder side; The weak feeder determination module is used to generate a weak feeder determination result based on the multiphase electrical quantities, the zero-sequence electrical quantities, and their respective weak feeder determination conditions. The signal detection module is used to detect the permission signal emitted by the longitudinal zero-sequence protection device on the zero-sequence non-weak feed side and obtain the signal detection result. The weak feed control module is used to control the operating state of the switching equipment on the zero-sequence weak feed side based on the weak feed determination result and the signal detection result.

10. An electronic device, comprising: One or more processors; Memory, used to store one or more computer programs. The characteristic feature is that the one or more processors execute the one or more computer programs to implement the steps of the method according to any one of claims 1 to 8.

Images