Auxiliary decision-making system for small-current grounding line selection

Abstract

The invention provides an auxiliary decision-making system for small-current grounding line selection, which realizes a single-phase grounding fault monitoring function by dynamically acquiring a real-time power grid model and data information, and intelligently judges whether a single-phase grounding fault exists or not according to a set monitoring target and a bus real-time operation condition. A single-phase grounding signal is prompted to a monitor in time; existing resources are fully utilized, whether arc suppression coil compensation exists in small-current grounding protection or not is intelligently judged, compensation degrees (undercompensation, overcompensation and full compensation) are identified, and a distinguishing management mode of different arc suppression coil compensation degrees is formulated by combining information (current, reactive power, time difference and the like) before and after a single-phase grounding fault occurs. A reasonable switching-off strategy sorting function is provided; the grounding historical record management function is achieved, complete historical grounding fault information and line selection strategy information are stored, the historical grounding fault information can be inquired conveniently and rapidly, and data support is provided for monitoring personnel to redisk and trace grounding faults.

Description

Technical Field

[0001] The invention belongs to the technical field of power system protection, and in particular relates to a small current grounding line selection auxiliary decision system. Background Art

[0002] In the actual operation of my country's power grid, the small current grounding system has very significant advantages. In the distribution network system with a voltage level of 3-35kV, most of them adopt the neutral point non-direct grounding method, that is, the neutral point is not grounded, the neutral point is grounded through the arc suppression coil, and the neutral point is grounded through a resistor (usually high resistance). There is no electrical connection between the system neutral line and the earth. When any phase of the feeder is in a ground short-circuit state, the impedance value of the fault circuit increases, the zero-sequence current flowing through the system is very small, and the healthy phase voltage increases to 1.732 times (approximately) the original, and the line voltage remains symmetrical. According to the current effective national power operation guidelines, the system can operate for 1-2 hours in a single-phase ground short-circuit state, which effectively improves the continuity of power supply, reduces the load loss on the user side, and demonstrates the superiority of the small current grounding system. my country's 35kV and below distribution network is generally a small current grounding system (using the neutral point not grounded or grounded through the arc suppression coil), among which single-phase grounding faults occur most frequently in the small current system. According to incomplete statistics, 80% of the transmission line faults below 35kV in the past three years were single-phase grounding faults.

[0003] While discovering the advantages of the small current grounding system, we must also recognize its existing problems, that is, the system should not run with a fault for too long. Since the healthy phase voltage rises to the line voltage, if it runs with a fault for a long time, it is very likely to cause electrical breakdown in the poorly insulated parts of the stable operating phase line, thereby indirectly forming a phase-to-phase short circuit and grounding, expanding the scope of the fault; once an arc effect is triggered at the short-circuit point, the system will be in danger of overvoltage, which will shorten the service life of the equipment at the least, and destroy the power operation equipment at the worst, seriously affecting the safe and reliable power supply of the power grid. When there are people moving around the grounding point, it may even pose a great threat to personal safety. Therefore, it is very necessary to accurately judge the grounding fault point as early as possible and eliminate the impact of the fault. Therefore, small current grounding line selection devices began to be developed, manufactured, and promoted. The line selection device automatically judges the grounding fault phase line, and promptly informs the power grid control personnel to implement targeted accident handling measures, thereby reducing the impact of the grounding fault on the stable operation of the power grid.

[0004] With the continuous expansion and complexity of the scale of the power system, combined with the above power grid situation, the traditional manual inspection and fault handling methods can no longer meet the needs. Therefore, the study of small current grounding technology can realize the intelligent detection and positioning of grounding faults and improve the automation level of the power system. Ji'an currently uses traditional manual processing methods, relying on manual and operating experience judgment, and the success rate of fault handling is not high, which cannot meet the technical specifications for the determination of single-phase grounding; there is a lack of grounding type judgment module, and it is impossible to distinguish between frequent and instantaneous grounding, which affects the determination process of single-phase grounding; there is a lack of arc suppression coil compensation degree differentiation management, and there is no strategy generation based on compensation degree, which seriously affects the correctness of the sequence of pulling strategy formation. Summary of the invention

[0005] In view of this, the present invention aims to overcome the shortcomings of the above-mentioned problems in the prior art and proposes a small current grounding line selection auxiliary decision system. When a grounding fault occurs, the system is used to detect and locate the grounding point so that timely measures can be taken to repair the fault and prevent further damage and accidents.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A small current grounding line selection auxiliary decision system, which obtains real-time grid underlying data through a database interface. The system combines the acquired underlying data to complete single-phase grounding fault monitoring, arc suppression coil compensation management, grounding line selection strategy generation, and historical record management, and displays the results through a workstation;

[0008] The system includes a single-phase grounding fault monitoring unit, an arc suppression coil compensation management unit, a grounding line selection strategy generation unit, and a historical record management unit;

[0009] The single-phase grounding fault monitoring unit realizes single-phase grounding fault analysis and judges bus grounding phenomenon by real-time monitoring of bus telemetry and telesignaling information. When a single-phase grounding fault occurs, it considers and eliminates the interference of instantaneous grounding fault and frequent grounding fault, realizes grounding fault type identification, and prompts alarm information.

[0010] The arc suppression coil compensation degree management unit is used to determine whether there is arc suppression coil compensation in the small current grounding protection, including full compensation, over compensation and under compensation, and identify the compensation degree;

[0011] The grounding line selection strategy generation unit is used to obtain information before and after the single-phase grounding fault occurs, and use local topology analysis, combined with the single-phase grounding fault line selection method, to formulate a differentiated management mode with different arc suppression coil compensation degrees, and provide a reasonable line pulling strategy sorting;

[0012] The history record management unit is used to save the ground fault records and display the strategy information associated with the monitoring bus in a friendly human-machine interface manner, so that the monitor can quickly query the historical ground faults.

[0013] Furthermore, the acquisition of real-time grid underlying data includes:

[0014] Obtain real-time power grid models, measurements, and parameters; obtain telemetry and telesignaling information by reading the real-time database, obtain bus line voltage and phase voltage data, and obtain load and line data associated with the grounded bus, including current value, reactive power value, current mutation, reactive power mutation, and zero-sequence current value.

[0015] Furthermore, the single-phase ground fault monitoring unit is implemented as follows:

[0016] Identify instantaneous grounding and frequent grounding faults: By effectively identifying the type of grounding fault, the time quantity is used for judgment, instantaneous grounding faults are eliminated, and frequent grounding faults are distinguished. For frequent grounding, the time difference between the current grounding and the last grounding is compared. The current grounding time of frequent grounding is the same as the last grounding time, and it is handled as continuous grounding. For instantaneous grounding, the occurrence time of this grounding needs to be monitored;

[0017] Single-phase grounding fault monitoring: Real-time monitoring of bus line voltage and phase voltage, to ensure that the three-phase voltage collection quality code is normal, and the voltage of any phase of the non-fault phase increases to the voltage high coefficient multiplied by the phase voltage threshold value, and the fault phase voltage drops to the voltage low coefficient multiplied by the phase voltage threshold value, the bus is judged to be grounded, otherwise the bus grounding is restored.

[0018] Furthermore, the phase voltage threshold value=line voltage / 1.732; the voltage high coefficient is set to 1.2, and the voltage low coefficient is set to 0.8.

[0019] Furthermore, the arc suppression coil compensation degree management unit is implemented as follows:

[0020] Confirm whether there is an arc suppression coil device in the model; if there is an arc suppression coil device, identify the compensation degree V of the arc suppression coil, distinguish between full compensation, over compensation and under compensation, and after correctly identifying the compensation degree, select different threshold values ​​of the pull-through control strategy according to whether there is an arc suppression coil and the compensation degree; among them,

[0021] V=(IC-IL) / IC

[0022] When V=0, it is called full compensation, when V>0 it is under compensation, and when V<0 it is over compensation.

[0023] Furthermore, the implementation process of the grounding line selection strategy generation unit is as follows:

[0024] By using local topology analysis, all outgoing lines under the grounding bus are obtained. According to the fault time information, the data of multiple sampling time points before and after the fault are read from the rolling stored electrical characteristic quantities. The electrical characteristic quantities before and after the fault are calculated, including: fault phase current and change before and after the fault, zero-sequence current and change, reactive power and change. Combined with the single-phase grounding fault line selection method, a grounding line selection strategy suitable for different arc suppression coil compensation degrees is provided.

[0025] Furthermore, the single-phase ground fault line selection method includes:

[0026] If there is no arc suppression coil or the arc suppression coil is under-compensated, the IQ fast calculation method is used;

[0027] The over-compensation and full compensation of arc extinguishing coils adopt the I / Q / I0 comprehensive calculation method.

[0028] Furthermore, the history record management unit is implemented as follows:

[0029] When the bus line voltage and phase voltage do not meet the three-phase grounding criterion, the grounding fault is considered to have disappeared;

[0030] From the perspective of the human-machine interface, the disappeared ground fault information is cleared from the small current ground line selection main interface, written into the historical records, and displayed through the historical record management tool.

[0031] Compared with the prior art, the low-current grounding line selection auxiliary decision system of the present invention has the following advantages:

[0032] (1) Compared with the traditional manual processing method, the small current grounding line selection system of the present invention can obtain real-time telesignaling and telemetry data from SCADA, intelligently judge grounding faults, promptly prompt the monitor with the "grounding fault" signal, and effectively identify instantaneous grounding faults and frequent grounding faults; obtain information such as the current change and reactive power change before and after the grounding fault occurs, and quickly provide grounding line selection strategies to provide reasonable fault probability ranking for control personnel, quickly lock the fault point, and provide intelligent and easy-to-use auxiliary decision-making systems for dispatching and monitoring personnel to eliminate single-phase grounding faults in time. Provide a friendly human-computer interaction interface, and adopt a clear functional module, intuitive and simple interface display style. The parameter setting module displays information such as the voltage high coefficient, voltage low coefficient, weight, etc. The grounding fault monitoring module displays detailed information of the grounding bus, and the line selection strategy module provides the final strategy ranking and related data.

[0033] (2) The present invention solves the problem of long ground fault handling cycle and inability to effectively reduce the scope of power outage due to differences in the professional level of power grid control personnel. It uses real-time, fast and intelligent ground fault monitoring and ground fault line selection modules to reduce the daily complicated and difficult business problems of dispatchers and improve the professional level of personnel.

[0034] (3) The present invention constructs a historical record management mode to save ground fault information and line selection strategy information, and records in detail the data basis related to the current ground fault, including phase voltage, line voltage, reactive power change, current change, etc., to provide support for control personnel to review or study frequent ground faults.

[0035] (4) The present invention further effectively ensures the stability of power grid operation, maintains urban power supply safety and power supply security, and protects social livelihood. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0037] Figure 1 This is a functional structure diagram of the small current grounding line selection auxiliary decision system of the present invention;

[0038] Figure 2 A single-phase grounding fault analysis flow chart of the present invention;

[0039] Figure 3 A flow chart is generated for the grounding line selection strategy of the present invention. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0044] In view of the existing single-phase grounding fault troubleshooting relying on manual experience and complex test pulling operations, the present invention provides a set of grounding bus monitoring and line selection strategy generation architecture system to achieve real-time monitoring of the whole network modeling bus, grounding signal prompts, distinguish between frequent and instantaneous grounding faults, quickly lock the fault point, provide line selection strategies, improve the response speed after the grounding fault occurs, and effectively ensure the power supply reliability of the local area of ​​the power grid and the safety of people's livelihood electricity use. The specific small current grounding line selection auxiliary decision-making system structure diagram is as follows: Figure 1 As shown, the main functional modules include:

[0045] (1) Single-phase ground fault monitoring unit

[0046] By real-time monitoring of busbar telemetry and telesignaling (phase voltage, line voltage) information, single-phase grounding fault analysis is realized, busbar grounding phenomenon is judged, and when a single-phase grounding fault occurs, the interference of instantaneous grounding faults and frequent grounding faults is considered and eliminated, the grounding fault type is identified, and the "single-phase grounding" alarm information is immediately prompted.

[0047] (2) Arc extinguishing coil compensation management unit

[0048] Utilize existing resources to intelligently determine whether arc suppression coil compensation exists in low current grounding protection, and identify the degree of compensation (undercompensation, overcompensation, and full compensation).

[0049] (3) Grounding line selection strategy generation unit

[0050] When a single-phase grounding fault occurs, obtain the information before and after the grounding (current, reactive power, time difference, etc.), use local topology analysis, combined with the single-phase grounding fault line selection method (IQ comprehensive method, zero-sequence current method, etc.), formulate a differentiated management mode for different arc suppression coil compensation degrees, and provide a reasonable line pulling strategy ranking.

[0051] (4) History Record Management Unit

[0052] Realize the preservation of ground fault records, and use a friendly human-machine interface to display the strategic information associated with the monitoring bus, so that the monitor can quickly query the historical ground faults.

[0053] The low-current grounding line selection auxiliary decision system of the present invention obtains real-time grid underlying data through a database interface. The system combines the acquired underlying data to complete single-phase grounding fault monitoring, arc suppression coil compensation management, grounding line selection strategy generation, and historical record management, and displays the results through a workstation. Specifically,

[0054] The underlying data is acquired through the database interface to obtain real-time power grid models, measurements, and parameters; by reading the real-time database, telemetry and telesignaling information are obtained, bus line voltage and phase voltage data are obtained, and load and line data associated with the grounded bus are obtained, including current value, reactive power value, current mutation, reactive power mutation, and zero-sequence current value.

[0055] The upper-layer functions are realized by combining the acquired underlying data to complete single-phase grounding fault monitoring, arc suppression coil compensation management, grounding line selection strategy generation, and historical record management.

[0056] The front-end data display realizes the display of the main function results of the system, including arc suppression coil identification information, grounding bus information, line selection strategy information, and global control parameter information such as calculation status.

[0057] Now combined Figure 2 , Figure 3 The functional method flow chart shown introduces the overall implementation process of the system as follows.

[0058] Step 1: Single-phase ground fault monitoring

[0059] (1) Identify instantaneous grounding and frequent grounding faults

[0060] Effectively identify the type of grounding fault, use time to judge, eliminate instantaneous grounding faults, and distinguish frequent grounding faults. Frequent grounding requires comparing the time difference between the current grounding and the last grounding (less than 45s). The current grounding time of frequent grounding is the same as the last grounding time, and is handled as continuous grounding. Instantaneous grounding requires monitoring the occurrence time of this grounding (maintained for 45s).

[0061] (2) Single-phase ground fault monitoring

[0062] Monitor the bus line voltage and phase voltage in real time to ensure that the three-phase voltage collection quality code is normal, and the voltage of any non-fault phase increases to the voltage high coefficient multiplied by the phase voltage threshold value, and the fault phase voltage drops to the voltage low coefficient multiplied by the phase voltage threshold value, and the bus is judged to be grounded. Otherwise, the bus grounding is restored.

[0063] Note: ① Phase voltage threshold value = line voltage / 1.732; ② Set the voltage high coefficient to 1.2 and the voltage low coefficient to 0.8.

[0064] Step 2: Generate grounding line selection strategy

[0065] (1) Identification of arc suppression coil compensation degree

[0066] First, confirm whether there is an arc suppression coil device in the model; second, if there is an arc suppression coil device, identify the compensation degree V of the arc suppression coil and distinguish between full compensation, over compensation and under compensation. After correctly identifying the compensation degree, it is necessary to comprehensively select different threshold values ​​of the pull-through control strategy based on whether there is an arc suppression coil and the compensation degree.

[0067] V=(IC-IL) / IC

[0068] When V=0, it is called full compensation, when V>0 it is under compensation, and when V<0 it is over compensation.

[0069] (2) Provide a reasonable route pulling strategy

[0070] By using local topology analysis, all outgoing lines under the grounding bus are obtained. According to the fault time information, multiple sampling time point data before and after the fault are read from the rolling stored electrical characteristic quantities, and the electrical characteristic quantities before and after the fault are calculated, including: fault phase current and change before and after the fault, zero sequence current and change, reactive power and change. Combined with the single-phase grounding fault line selection method (IQ fast calculation method or I / Q / I0 comprehensive calculation method), a grounding line selection strategy suitable for different arc suppression coil compensation degrees is provided.

[0071] When there is no arc extinguishing coil or the arc extinguishing coil is under-compensated, the IQ fast calculation method is used; when the arc extinguishing coil is over-compensated or even fully compensated, the I / Q / I0 comprehensive calculation method is used.

[0072] Step 3: History Management

[0073] Ground bus information storage

[0074] When the bus line voltage and phase voltage do not meet the three-phase grounding criteria, it is considered that the grounding fault has disappeared.

[0075] From the perspective of the human-machine interface, the disappeared ground fault information is cleared from the small current ground line selection main interface, written into the historical records, and displayed through the historical record management tool.

[0076] History management tools:

[0077] Supports sorting in chronological order;

[0078] Supports searching by bus name;

[0079] Supports querying the type of ground fault, and measuring the line voltage and phase voltage when ground fault occurs;

[0080] Supports querying grounding line selection strategy information, including but not limited to fault probability ranking, reactive power mutation, and current mutation.

[0081] The present invention realizes the function of single-phase grounding fault monitoring by dynamically acquiring real-time power grid model and data information, and intelligently determines whether there is a single-phase grounding fault according to the set monitoring target and the real-time operation status of the busbar, and promptly prompts the monitor with the "single-phase grounding" signal; fully utilizes existing resources, intelligently determines whether there is arc suppression coil compensation in the small current grounding protection, and identifies the compensation degree (undercompensation, overcompensation and full compensation), and combines the information before and after the single-phase grounding fault occurs (current, reactive power, time difference, etc.) to realize the formulation of differentiated management modes for different arc suppression coil compensation degrees, and provides the function of reasonable line pulling strategy sorting; realizes the function of grounding history record management, saves complete historical grounding fault information and line selection strategy information, facilitates and quickly queries historical grounding fault information, and provides data support for monitors to review and trace grounding faults.

[0082] The system of the present invention can reduce the energy loss caused by grounding faults and improve the requirements for the operation efficiency of the power grid. It can improve the rapidity and correctness of the operating system in judging the grounding line, quickly solve the grounding fault, reduce the number of push and pull times, shorten the time for handling the grounding fault, improve the safe and stable operation level of the power grid, and bring great economic and social benefits to the operation of the power grid. It can significantly improve the intelligence and automation level of the control system and reduce the workload of the control personnel.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Small current grounding line selection auxiliary decision system, characterized by: The system obtains real-time grid underlying data through a database interface. The system combines the acquired underlying data to complete single-phase grounding fault monitoring, arc suppression coil compensation management, grounding line selection strategy generation, and historical record management, and displays the results through a workstation; The system includes a single-phase grounding fault monitoring unit, an arc suppression coil compensation management unit, a grounding line selection strategy generation unit, and a historical record management unit; The single-phase grounding fault monitoring unit realizes single-phase grounding fault analysis and judges bus grounding phenomenon by real-time monitoring of bus telemetry and telesignaling information. When a single-phase grounding fault occurs, it considers and eliminates the interference of instantaneous grounding fault and frequent grounding fault, realizes grounding fault type identification, and prompts alarm information. The arc suppression coil compensation degree management unit is used to determine whether there is arc suppression coil compensation in the small current grounding protection, including full compensation, over compensation and under compensation, and identify the compensation degree; The grounding line selection strategy generation unit is used to obtain information before and after the single-phase grounding fault occurs, and use local topology analysis, combined with the single-phase grounding fault line selection method, to formulate a differentiated management mode with different arc suppression coil compensation degrees, and provide a reasonable line pulling strategy sorting; The history record management unit is used to save the ground fault records and display the strategy information associated with the monitoring bus in a friendly human-machine interface manner, so that the monitor can quickly query the historical ground faults.

2. The small current grounding line selection auxiliary decision system according to claim 1 is characterized in that: The acquisition of real-time grid underlying data includes: Obtain real-time power grid models, measurements, and parameters; obtain telemetry and telesignaling information by reading the real-time database, obtain bus line voltage and phase voltage data, and obtain load and line data associated with the grounded bus, including current value, reactive power value, current mutation, reactive power mutation, and zero-sequence current value.

3. The small current grounding line selection auxiliary decision system according to claim 1 is characterized in that: The single-phase ground fault monitoring unit is implemented as follows: Identify instantaneous grounding and frequent grounding faults: By effectively identifying the type of grounding fault, the time quantity is used for judgment, instantaneous grounding faults are eliminated, and frequent grounding faults are distinguished. For frequent grounding, the time difference between the current grounding and the last grounding is compared. The current grounding time of frequent grounding is the same as the last grounding time, and it is handled as continuous grounding. For instantaneous grounding, the occurrence time of this grounding needs to be monitored; Single-phase grounding fault monitoring: Real-time monitoring of bus line voltage and phase voltage, to ensure that the three-phase voltage collection quality code is normal, and the voltage of any phase of the non-fault phase increases to the voltage high coefficient multiplied by the phase voltage threshold value, and the fault phase voltage drops to the voltage low coefficient multiplied by the phase voltage threshold value, the bus is judged to be grounded, otherwise the bus grounding is restored.

4. The small current grounding line selection auxiliary decision system according to claim 3 is characterized in that: The phase voltage threshold value = line voltage / 1.732; the voltage high coefficient is set to 1.2, and the voltage low coefficient is set to 0.

8.

5. The small current grounding line selection auxiliary decision system according to claim 1 is characterized in that: The arc suppression coil compensation degree management unit is implemented as follows: Confirm whether there is an arc suppression coil device in the model; if there is an arc suppression coil device, identify the compensation degree V of the arc suppression coil, distinguish between full compensation, over compensation and under compensation, and after correctly identifying the compensation degree, select different threshold values ​​of the pull-through control strategy according to whether there is an arc suppression coil and the compensation degree; among them, V=(IC-IL) / IC When V=0, it is called full compensation, when V>0 it is under compensation, and when V<0 it is over compensation.

6. The small current grounding line selection auxiliary decision system according to claim 1 is characterized in that: The implementation process of the grounding line selection strategy generation unit is as follows: By using local topology analysis, all outgoing lines under the grounding bus are obtained. According to the fault time information, the data of multiple sampling time points before and after the fault are read from the rolling stored electrical characteristic quantities. The electrical characteristic quantities before and after the fault are calculated, including: fault phase current and change before and after the fault, zero-sequence current and change, reactive power and change. Combined with the single-phase grounding fault line selection method, a grounding line selection strategy suitable for different arc suppression coil compensation degrees is provided.

7. The small current grounding line selection auxiliary decision system according to claim 6 is characterized in that: The single-phase ground fault line selection method comprises: If there is no arc suppression coil or the arc suppression coil is under-compensated, the IQ fast calculation method is used; The over-compensation and full compensation of arc extinguishing coils adopt the I / Q / I0 comprehensive calculation method.

8. The small current grounding line selection auxiliary decision system according to claim 1 is characterized in that: The history record management unit is implemented as follows: When the bus line voltage and phase voltage do not meet the three-phase grounding criterion, the grounding fault is considered to have disappeared; From the perspective of the human-machine interface, the disappeared ground fault information is cleared from the small current ground line selection main interface, written into the historical records, and displayed through the historical record management tool.

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