New energy power station single-phase ground fault comprehensive protection system and method

Abstract

The application relates to the field of power system protection, and discloses a new energy power station single-phase grounding fault comprehensive protection system and method, which comprises the following: a line remote measurement module for detecting the current and voltage of each line in the power station; a comprehensive grounding protection device for switching to a corresponding mode according to the neutral point setting mode of the power station; based on the current and voltage of each line and the on-off position state of the circuit breaker of the power station, logical operation is performed to determine whether a grounding fault occurs; corresponding control signals are sent according to the determination result; and an automatic circuit breaker device is connected to the grounding branch of the power station, and when the automatic circuit breaker device receives the control signals, the automatic circuit breaker device is closed or opened to realize the operation of the power station in the grounding mode or the non-grounding mode, so that the problems of the existing grounding protection device, such as the limited application range, the limited function and the refusal of the original line protection device, are solved.

Description

Technical Field

[0001] This invention relates to the field of power system protection, specifically to a comprehensive protection system and method for single-phase grounding faults in new energy power plants. Background Technology

[0002] With the rapid development of new energy sources, wind and photovoltaic power generation are gradually increasing in scale and occupying an increasingly important position in the new energy field. However, the most common failure rate in new energy power plants is currently single-phase grounding faults, with a failure rate of 60% to 70%. The causes of these faults may include single-phase grounding of the transmission line, insulation breakdown leading to single-phase grounding, etc. Once a single-phase grounding fault occurs, the line protection device trips, and the corresponding circuit breaker trips, thus eliminating the single-phase grounding fault. However, current single-phase grounding fault isolation devices have the following problems:

[0003] (1) Limited applicability of the device: Conventional new energy power plants are divided into two design modes: with main transformer and without main transformer. These two design modes have their own characteristics. At present, there is no ground fault protection system that can integrate the two different design modes, which greatly reduces the versatility of the device. This device system can complete the design modes of different power plants.

[0004] (2) Functional limitations: Current grounding protection devices cannot automatically switch the grounding resistance operation mode. The isolation switch is manually operated mechanically. When a single-phase grounding fault occurs, the grounding resistance operation mode cannot be switched in time, which poses a risk of continuous current passing through and burning out the resistor, resulting in significant economic losses.

[0005] The original line protection device, used as a backup protection system, fails to operate when a single-phase ground fault occurs, preventing the fault from being cleared and potentially causing further escalation and significant economic losses. This new device can reactivate the circuit breaker, causing it to disconnect. Once the circuit breaker at the low-resistance point is disconnected, the system becomes ungrounded, and the protection device ceases to function and protect against ground faults. However, the device can still operate after the circuit breaker at the low-resistance point has been disconnected. Summary of the Invention

[0006] In view of this, the present invention provides a comprehensive protection system and method for single-phase grounding faults in new energy power plants, in order to solve the problems of limited applicability, limited function, and failure of the original line protection device to operate in existing grounding protection devices.

[0007] In a first aspect, the present invention provides a comprehensive protection system for single-phase grounding faults in a new energy power station, comprising: a line telemetry module, a comprehensive grounding protection device, and an automatic circuit breaker device. The line telemetry module is used to detect the current and voltage of each line within the power station; the comprehensive grounding protection device is used to switch to the corresponding mode according to the neutral point setting method of the power station; based on the current and voltage of each line and the open / closed position of the power station's circuit breaker, it performs logical operations to determine whether a grounding fault has occurred; and issues a corresponding control signal based on the determination result; the automatic circuit breaker device is connected in series to the grounding branch of the power station, and when the automatic circuit breaker device receives the control signal, it closes or opens to achieve grounded or ungrounded operation of the power station.

[0008] This invention addresses the issue of switching between different operating modes based on the neutral point setting method, and realizes grounding protection for multiple lines based on the current and voltage of each line and the opening and closing position of the power station circuit breaker, thereby solving the problems of limited applicability, limited function, and failure of the original line protection device to operate in existing grounding protection devices.

[0009] In one optional implementation, the integrated grounding protection device includes: an analog signal input module, a digital signal input module, an analog-to-digital converter module, a logic judgment module, a digital signal output module, a mode conversion module, and a human-machine interface module. The analog signal input module is used to acquire the current and voltage signals from the current transformer and voltage transformer, and transmit these signals to the analog-to-digital converter module. The digital signal input module is used to acquire the circuit breaker opening and closing position status of the corresponding circuit breaker, and transmit this status to the logic judgment module. The analog-to-digital converter module converts the analog signals from the analog signal input module into digital signals, and then converts the digital signals into digital signals. The signal is transmitted to the logic judgment module; the logic judgment module compares the amplitude and phase based on the current and voltage of each line obtained by the line telemetry module, and combines the circuit breaker's open / close position status to determine whether a ground fault has occurred through logical operations; the switch signal output module receives the logic judgment result from the logic judgment module and outputs the corresponding circuit breaker control signal; the mode conversion module switches the working mode of the integrated grounding protection equipment according to the neutral point setting method of the power station; the human-machine interaction module is used for manual control and searching of the system's operating status, and the operator can switch the working mode of the mode conversion module through the human-machine interaction module.

[0010] In one optional implementation, the operating modes include: grounding mode of a new energy power station without main transformer boosting via grounding transformer with reduced resistance, grounding mode of a new energy power station with main transformer boosting via main transformer low-voltage side neutral point resistance, and grounding mode of a new energy power station with main transformer boosting via grounding transformer with reduced resistance.

[0011] Secondly, the present invention provides a comprehensive protection method for single-phase grounding faults in a new energy power station, applied to the comprehensive grounding protection device of the second optional embodiment of the first aspect. The method includes: acquiring the current and voltage of each line in the power station detected by the line telemetry module; switching to the corresponding mode according to the neutral point setting method of the power station; determining whether a grounding fault has occurred based on the amplitude and phase of the current and voltage of each line and the opening and closing position status of the power station circuit breaker through logical operations; issuing a corresponding control signal according to the determination result; the control signal is used to control the automatic circuit breaker device to close or open, so as to realize the operation of the power station in grounded mode or ungrounded mode.

[0012] In one alternative implementation, the power station includes collector lines, grounding lines, grounding transformer branches, transmission lines, busbars, and other lines.

[0013] In one optional implementation, the process of issuing a corresponding control signal based on the judgment result for any collector line includes: when the operating mode is the grounding mode of a new energy power station without main transformer boosting via grounding transformer low resistance, if the zero-sequence voltage amplitude of the bus is greater than or equal to a preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to a preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to a preset grounding transformer current threshold, and the zero-sequence current amplitude of the collector line is greater than or equal to a preset collector line current threshold, then control... The automatic circuit breaker trips; after a preset time, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, the automatic circuit breaker is kept in the tripped state, and the circuit breaker on the collector line is opened; otherwise, the automatic circuit breaker is closed. When the operating mode is the grounding mode of the new energy power station via the main transformer's low-voltage side neutral point resistance, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, and the zero-sequence current of the transmission line is... If the amplitude of the grounding transformer current is greater than or equal to the preset grounding transformer current threshold, or if the amplitude of the zero-sequence current of the collector line is greater than or equal to the preset collector line current threshold, the automatic circuit breaker will be controlled to open. After a preset time, if the amplitude of the zero-sequence voltage of the busbar is greater than or equal to the preset busbar voltage threshold, the automatic circuit breaker will be controlled to remain open, and the circuit breaker on the collector line will be controlled to open; otherwise, the automatic circuit breaker will be controlled to close. When the operating mode is the grounding mode of the new energy power station with voltage boosted by the main transformer and grounded by the grounding transformer with low resistance, if the amplitude of the zero-sequence voltage of the busbar is greater than or equal to... If the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of the collector line is greater than or equal to the preset collector line current threshold, the automatic circuit breaker will be controlled to open. After a preset time, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, the automatic circuit breaker will be controlled to remain in the open state, and the circuit breaker on the collector line will be controlled to open. Otherwise, the automatic circuit breaker will be controlled to close.

[0014] In one optional implementation, when at least one collector line experiences a permanent single-phase ground fault, the process of issuing a corresponding control signal based on the judgment result further includes: for any unfaulted collector line, if the bus zero-sequence voltage amplitude is greater than or equal to a preset bus voltage threshold, the collector line zero-sequence current amplitude is greater than or equal to a preset collector line current threshold, and the collector line phase angle is greater than or equal to -180° and less than or equal to 0°, then the circuit breaker on that collector line is controlled to open; for any other line, if the bus zero-sequence voltage amplitude is greater than or equal to a preset bus voltage threshold, the other line zero-sequence current amplitude is greater than or equal to a preset other line current threshold, and the other line phase angle is greater than or equal to -180° and less than or equal to 0°, then the circuit breaker on that other line is controlled to open.

[0015] In one optional implementation, the process of issuing a corresponding control signal based on the judgment result further includes: if the zero-sequence voltage amplitude of the bus is greater than or equal to a preset bus voltage threshold, the zero-sequence current amplitude of the transmitting line is greater than or equal to a preset transmitting line current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to a preset grounding transformer current threshold, and the zero-sequence current amplitude of all collector lines is greater than or equal to a collector line current threshold, and at the same time the phase angle of the transmitting line, the grounding transformer branch, and all collector lines is greater than or equal to -180° and less than or equal to 0°, then the circuit breakers on the transmitting line, the grounding transformer branch, and all collector lines are controlled to open.

[0016] In one optional implementation, the process of issuing a corresponding control signal based on the judgment result for any other line includes: when the operating mode is the grounding mode of a new energy power station without main transformer boosting via grounding transformer low-resistance, if the bus zero-sequence voltage amplitude is greater than or equal to a preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to a preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to a preset grounding transformer current threshold, and the zero-sequence current amplitude of other lines is greater than or equal to a preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain open, and the circuit breaker on the other line is controlled to open; otherwise, the automatic circuit breaker device is controlled to close; when the operating mode is the grounding mode of a new energy power station with main transformer boosting via main transformer low-voltage side neutral point resistance, if the bus zero-sequence voltage amplitude is greater than or equal to a preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to a preset grounding current threshold, and the zero-sequence current amplitude of the transmitting line is greater than or equal to a preset collector line current threshold, then the automatic circuit breaker device is controlled to close; after a preset time, if the bus zero-sequence voltage amplitude is greater than or equal to a preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to a preset grounding current threshold, and the zero-sequence current amplitude of the transmitting line is greater than or equal to a preset collector line current threshold, then the automatic circuit breaker device is controlled to close; If the amplitude of the zero-sequence current is greater than or equal to the preset grounding transformer current threshold, and the amplitude of the zero-sequence current on other lines is greater than or equal to the preset collector line current threshold, the automatic circuit breaker will be controlled to open. After a preset time, if the amplitude of the zero-sequence voltage on the busbar is greater than or equal to the preset busbar voltage threshold, the automatic circuit breaker will be controlled to remain open, and the circuit breakers on other lines will be controlled to open; otherwise, the automatic circuit breaker will be controlled to close. When the operating mode is the new energy power station with voltage boosted by the main transformer and grounded through the grounding transformer with low resistance, if the amplitude of the zero-sequence voltage on the busbar is greater than or equal to... If the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude on the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, or the zero-sequence current amplitude on other lines is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker will be controlled to open. After a preset time, if the zero-sequence voltage amplitude on the bus is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker will be controlled to remain open, and the circuit breakers on the other lines will be controlled to open. Otherwise, the automatic circuit breaker will be controlled to close.

[0017] In an optional implementation, when at least one other line experiences a permanent single-phase ground fault, the process of issuing a corresponding control signal based on the judgment result further includes: for any collector line, if the bus zero-sequence voltage amplitude is greater than or equal to a preset bus voltage threshold, the collector line zero-sequence current amplitude is greater than or equal to a preset collector line current threshold, and the phase angle of the collector line is greater than or equal to -180° and less than or equal to 0°, then the circuit breaker on the collector line is controlled to open.

[0018] In one optional implementation, the process of issuing a corresponding control signal based on the judgment result further includes: if the zero-sequence voltage amplitude of the bus is greater than or equal to a preset bus voltage threshold, the zero-sequence current amplitude of the transmitting line is greater than or equal to a preset transmitting line current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to a preset grounding transformer current threshold, and the zero-sequence current amplitude of all collector lines is greater than or equal to a collector line current threshold, and at the same time the phase angle of the transmitting line, the grounding transformer branch, and all collector lines is greater than or equal to -180° and less than or equal to 0°, then the circuit breakers on the transmitting line, the grounding transformer branch, and all collector lines are controlled to open.

[0019] In one optional implementation, for a grounding transformer line, the process of issuing a corresponding control signal based on the judgment result includes: if the amplitude of the zero-sequence voltage of the bus is greater than or equal to a preset bus voltage threshold and the amplitude of the zero-sequence current on the grounding line is greater than or equal to a preset grounding current threshold, then the automatic circuit breaker device is controlled to remain in the open state, and after a preset time, the circuit breaker on the grounding transformer line is controlled to open; if the difference between the amplitude of any phase current of the bus and the amplitude of its zero-sequence current is greater than or equal to a preset current difference, then the circuit breaker on the grounding transformer line is controlled to open.

[0020] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the comprehensive protection method for single-phase grounding faults in new energy power plants as described in the second aspect above or any corresponding embodiment.

[0021] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions, which are used to cause a computer to execute the comprehensive protection method for single-phase grounding faults in new energy power plants according to the second aspect above or any corresponding embodiment.

[0022] Fifthly, the present invention provides a computer program product, including computer instructions, which are used to cause a computer to execute the comprehensive protection method for single-phase grounding faults in new energy power plants described in the second aspect above or any corresponding embodiment. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1This is a detailed structural diagram of an automatic circuit breaker device according to an embodiment of the present invention;

[0025] Figure 2 This is a detailed structural diagram of the integrated grounding protection device according to an embodiment of the present invention;

[0026] Figure 3 This is a detailed structural diagram of the analog signal input module, the digital signal input module, and the digital signal output module according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the mode conversion module and the logic judgment module according to an embodiment of the present invention;

[0028] Figure 5 This is a flowchart illustrating the integrated grounding fault protection method according to an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the grounding protection system structure of a new energy power station without main transformer step-up grounding mode—grounding protection system with grounding transformer small resistance, according to an embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of the grounding system protection of a new energy power station with voltage boosted by the main transformer and grounded through the neutral point resistance of the low-voltage side of the main transformer, according to an embodiment of the present invention.

[0031] Figure 8 This is a schematic diagram of the grounding system protection of a new energy power station with a grounding transformer and a small resistance grounding mode according to an embodiment of the present invention;

[0032] Figure 9 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This embodiment provides a comprehensive protection system for single-phase grounding faults in a new energy power plant, including: a line telemetry module, a comprehensive grounding protection device, and an automatic circuit breaker device.

[0035] Specifically, the line telemetry module is used to detect the current and voltage of each line in the power station; the line telemetry module includes: current transformers and voltage transformers installed on each line. The current transformers and voltage transformers are used to detect the current and voltage of the corresponding line and transmit the corresponding current and voltage signals to the integrated grounding protection equipment.

[0036] Specifically, the integrated grounding protection equipment is used to switch to the corresponding mode according to the neutral point setting method of the power station; based on the current and voltage of each line and the opening and closing position status of the power station circuit breaker, it performs logical operations to determine whether a grounding fault has occurred; and issues corresponding control signals according to the judgment result.

[0037] Specifically, the automatic circuit breaker device is connected in series with the grounding branch of the power station. When the automatic circuit breaker device receives a control signal, it closes or opens to achieve grounded or ungrounded operation of the power station. Optionally, such as Figure 1 As shown, the automatic circuit breaker device includes a circuit breaker (DL) and a disconnecting switch (GL). GL is used to open / close the grounding transformer low-resistance line branch. When the disconnecting switch is in the closed position, it indicates that the line is connected and the system operates in low-resistance grounding mode; when the disconnecting switch is in the open position, it indicates that the line is disconnected and the system operates in ungrounded mode.

[0038] In some alternative implementations, such as Figure 2 As shown, the integrated grounding protection device includes: an analog signal input module, a digital signal input module, an analog-to-digital conversion module, a logic judgment module, a digital signal output module, a mode conversion module, and a human-machine interaction module.

[0039] Specifically, the analog signal input module is used to acquire the current and voltage signals from the current transformer and voltage transformer, and transmit the current and voltage signals to the analog-to-digital converter module; such as Figure 3 As shown, the analog signal input module includes several analog input signal interfaces, from the first analog input signal interface to the tenth analog input signal interface. Each interface corresponds to a different analog signal source, that is, to a current transformer and a voltage transformer at different locations. At the same time, the number of corresponding analog signal input interfaces can be increased according to the needs of the equipment.

[0040] Specifically, the switch signal input module is used to collect the circuit breaker open / close position status of the corresponding circuit breaker and transmit the circuit breaker open / close position status to the logic judgment module; such as Figure 3 As shown, the switch signal input module includes several switch signal input interfaces, from the first switch signal input interface to the tenth switch signal input interface. Each interface corresponds to the "opening and closing" status of the circuit breaker at different locations, and is used to collect the "opening and closing" status of the circuit breaker in real time.

[0041] Specifically, the analog-to-digital converter module is used to convert the analog signals from the analog signal input module into digital signals and transmit the digital signals to the logic judgment module.

[0042] Specifically, the logic judgment module compares the amplitude and phase of the current and voltage of each line obtained by the line telemetry module, and combines this with the circuit breaker's open / close position status to determine whether a ground fault has occurred through logical operations. The switch signal output module receives the logic judgment result from the logic judgment module and outputs the corresponding circuit breaker control signal, namely the corresponding circuit breaker "open" and "close" signals, to control the circuit breaker's open / close and achieve state switching. The switch signal output module includes several switch signal output interfaces, including a first switch signal output interface and a tenth switch signal output interface, which are respectively connected to the circuit breaker's "open / close" circuit at the corresponding position to realize the "open / close" control of the circuit breaker at different positions.

[0043] Specifically, the switch signal output module receives the logic judgment result from the logic judgment module and outputs the corresponding circuit breaker control signal, that is, outputs the corresponding circuit breaker "open" and "close" signals to control the circuit breaker's opening and closing, thereby achieving state switching; for example... Figure 3 As shown, the switch signal output module includes several switch signal output interfaces, a first switch signal output interface and a tenth switch signal output interface, which are respectively connected to the "opening and closing" circuit of the circuit breaker at the corresponding position to realize the "opening and closing" control of the circuit breaker at different positions.

[0044] Specifically, such as Figure 4 As shown, the mode conversion module is used to switch the working mode of the integrated grounding protection device according to the neutral point setting method of the power station. Different working modes correspond to different logic judgments. Optionally, the working modes include: grounding mode of the new energy power station without main transformer step-up through grounding transformer low resistance, grounding mode of the new energy power station with main transformer step-up through main transformer low voltage side neutral point resistance, and grounding mode of the new energy power station with main transformer step-up through grounding transformer low resistance.

[0045] Specifically, the new energy power station without main transformer step-up uses a grounding transformer with low resistance grounding mode: This design does not have a main transformer, and the system uses a Z-type grounding transformer with a neutral point grounded through a low resistance grounding method; The main transformer neutral point grounding mode is where the new energy power station has a main transformer, and the neutral point of the Y-type winding on the low-voltage side of the main transformer is grounded through a low resistance to achieve system grounding; The main transformer with grounding transformer with low resistance grounding mode is where the new energy power station has a main transformer, but the neutral point cannot be led out from the low-voltage side of the main transformer, so it is grounded through a Z-type grounding transformer with a low resistance grounding to achieve system grounding.

[0046] Specifically, the human-computer interaction module is used for human control and to check the operating status of the system. At the same time, staff can use the human-computer interaction module to switch the working modes of the mode conversion module.

[0047] Specifically, the automatic circuit breaker device is installed on the grounding resistor branch and connected to the grounding resistor to realize the switching of the grounding resistor's operating mode. The "open" and "close" signals of the automatic circuit breaker device come from the switch signal output module. When the switch signal output module outputs a "close" signal, the automatic circuit breaker device automatically "closes," and the new energy power station system operates in grounded mode. When the switch signal output module outputs a "open" signal, the automatic circuit breaker device automatically "opens," and the new energy power station system operates in ungrounded mode, thereby realizing the switching of the grounding resistor's operating mode.

[0048] This embodiment provides a comprehensive protection method for single-phase grounding faults in new energy power plants, applied to integrated grounding protection equipment, such as... Figure 5 As shown, the method includes:

[0049] Step S1: Obtain the current and voltage of each line in the power station detected by the line telemetry module.

[0050] Step S2: Switch to the corresponding mode according to the neutral point setting method of the power station.

[0051] Step S3: Based on the amplitude and phase of the current and voltage of each line, and the opening and closing position of the circuit breaker in the substation, a logic operation is performed to determine whether a ground fault has occurred. Based on the determination result, a corresponding control signal is issued. The control signal is used to control the automatic circuit breaker to close or open, thereby enabling the substation to operate in grounded or ungrounded mode.

[0052] In some alternative implementations, the power station includes collector lines, grounding lines, grounding transformer branches, transmission lines, busbars, and other lines.

[0053] Specifically, the new energy power station includes several lines, including: one busbar, one transmission line, and multiple branch lines; wherein the transmission line is connected to the busbar; the multiple branch lines are connected to the busbar; the multiple branch lines include: collector line branch lines, SVG branch lines, 35kV busbar branch lines, grounding transformer branch lines, station service transformer branch lines, and low-voltage side branch lines of the main transformer; the busbar is equipped with the voltage transformer; the multiple branch lines are respectively equipped with the current transformer and the voltage transformer; the voltage transformer and the current transformer are respectively connected to the line telemetry module; the voltage transformer on the busbar is used to detect the busbar voltage; the current transformer on each branch line is used to detect the current on each branch line.

[0054] There are two types of grounding methods for power plants: effective grounding and ineffective grounding. According to national standards, all new energy power plants are operated using the resistance grounding method. In order to maintain power supply reliability, the distribution network can be operated using the ungrounded method.

[0055] There are three types of ineffective grounding methods: low-resistance neutral point grounding, high-resistance neutral point grounding, and resonant neutral point grounding. Most renewable energy power plants operate using low-resistance grounding; therefore, this embodiment mainly focuses on the low-resistance grounding scheme.

[0056] Because different new energy power plants have different design modes, the operating mode of this protection system is switched to the corresponding operating mode through the mode conversion module. At the same time, different operating modes result in different wiring methods for grounding protection equipment; therefore, the following will describe three different modes.

[0057] Mode 1: Grounding mode of a new energy power station without main transformer boosting via grounding transformer with low resistance.

[0058] Figure 6 This is a schematic diagram of the grounding protection system structure for a new energy power station that has not undergone main transformer voltage boosting, using a grounding transformer with reduced resistance grounding mode. Figure 6 The physical parameters are as follows:

[0059] (1) L1 represents 35kV0, L2 represents 35kV transmission line, L3 represents grounding transformer line, L4 and L5 represent collector lines, L6 represents other lines; L7 represents grounding resistance branch; the collector lines can be one or more, and the number of them is not specifically limited in this embodiment. The number of modules is increased according to the number of lines.

[0060] (2) PT, or voltage transformer, is installed on line L1, i.e., on the 35kV busbar, to detect the open delta voltage of the 35kV busbar, also known as the zero-sequence voltage of the 35kV busbar, which can be denoted as 3U0. This signal is transmitted to the tenth analog signal interface; at the same time, the PT voltage transformer can also transmit the measured three-phase voltage on the 35kV busbar, denoted as U. A U B U C Transmit the signal to the seventh analog signal interface A07.

[0061] (3) T represents a Z-type grounding transformer, from which a neutral line is drawn.

[0062] (4) CT represents current transformer, which is used to measure line current; among them, CT1 represents the first current transformer, CT2 represents the second current transformer, CT3 represents the third current transformer, CT4 represents the fourth current transformer, and CT5 represents the fifth current transformer.

[0063] The first current transformer (zero-sequence current transformer) of CT1 is used to collect the zero-sequence current on the transmitting line L2, denoted as 3I. 01 The signal is transmitted to the first analog input signal interface A01.

[0064] The second current transformer (zero-sequence current transformer) of CT2 is used to collect the zero-sequence current on the grounding transformer branch L3, denoted as 3I. 02 The signal is then transmitted to the second analog input signal interface A02.

[0065] The third current transformer (zero-sequence current transformer) of CT3 is used to collect the zero-sequence current on collector line L4, denoted as 3I. 03 The signal is then transmitted to the third analog input signal interface A03.

[0066] The fourth current transformer (zero-sequence current transformer) CT4 is used to collect the zero-sequence current on collector line L5, denoted as 3I. 04 The signal is then transmitted to the fourth analog input signal interface A04.

[0067] The fourth current transformer (zero-sequence current transformer) of CT5 is used to collect the zero-sequence current on other lines L6, denoted as 3I. 05 The signal is then transmitted to the fifth analog input signal interface A05.

[0068] The CT6 current transformer is used to collect the three-phase current on line L3 of the grounding transformer, denoted as I. A I B I C The signal is then transmitted to the eighth analog input signal interface A08.

[0069] The CT current transformer (zero-sequence current transformer) is used to collect the zero-sequence current on a low-resistance line, denoted as 3I0, and transmits the signal to the ninth interface A09 of the analog input signal.

[0070] (5) R represents the grounding small resistance, which is used in the small resistance grounding system. The system is grounded through this small resistance.

[0071] (6) GL represents a disconnecting switch, used to open / close the low-resistance branch of the grounding transformer. When the disconnecting switch is in the closed position, it means that the line is connected and the system operates in low-resistance grounding mode; when the disconnecting switch is in the open position, it means that the line is disconnected and the system operates in ungrounded mode.

[0072] (7) T represents the grounding transformer, which is used to provide an artificial neutral point. The line is led out from the neutral point of the grounding transformer and finally grounded through the GL disconnect switch, DL circuit breaker, small resistor R, and zero-sequence current transformer CT.

[0073] (8) 10- indicates a comprehensive grounding system protection device, used for grounding system protection and control; the comprehensive grounding protection device includes: an analog signal input module, a digital signal input module, an analog-to-digital conversion module, a logic judgment module, a digital signal output module, a mode conversion module, and a human-machine interaction module;

[0074] 9- indicates an automatic circuit breaker device used to open / close a grounding low-resistance line. When both automatic circuit breakers are in the closed position (i.e., both circuit breaker DL and disconnector GL are in the closed position), the grounding low-resistance line is in a conducting state, and the new energy power station operates in low-resistance grounding mode. When the automatic circuit breaker is in the open position, the grounding low-resistance line is in an open state, and the new energy power station operates in ungrounded mode.

[0075] 9- indicates an automatic circuit breaker device, which includes a disconnecting switch GL and a circuit breaker DL, used to control the on / off state of the grounding transformer branch L7, thereby achieving the switching of the grounding mode. The circuit breaker type is a vacuum circuit breaker or an SF6 circuit breaker.

[0076] (9) L1 is called the 35kV bus. PT, or zero-sequence voltage transformer, is located on the L1 line and is used to detect the open delta voltage of the 35kV bus, or the zero-sequence voltage of the 35kV bus, which can be denoted as 3U0.

[0077] L2 is called the transmission line, and CT1, the first current transformer, is the zero-sequence current transformer on the 35kV transmission line. This zero-sequence current transformer can detect the zero-sequence current on the transmission line L2, and can be denoted as 3I01.

[0078] L3 is called the grounding transformer branch, which includes the grounding transformer (T) and the small resistance branch on the grounding transformer branch. The high-voltage side of the grounding transformer T is connected to the busbar, and the neutral point of the grounding transformer T is grounded in sequence through the disconnecting switch GL, the circuit breaker DL, and the resistor R. The connection group of this grounding transformer is ZN connection or ZNyn connection, where Z indicates that the primary winding is Z-type connection, y indicates that the secondary winding is star connection, and N and n indicate the neutral line is led out.

[0079] In this scenario, the fault types involved are categorized as follows: grounding faults in collector lines L4 and L5, and other lines L6; grounding faults in 35kV busbar L1; and grounding / phase-to-phase faults in grounding transformer line L3.

[0080] (1) For a ground fault occurring in collector line L4, the following judgment and protection methods are available:

[0081] At time t1, 3U0≥U set 3I0≥I set、 3I 02 ≥I set 3I 03≥I set The integrated grounding protection device 10 disconnects the DL circuit breaker, and the system switches from operating in the low-resistance grounding mode to operating in the ungrounded mode.

[0082] After time t1 to t2, the integrated grounding protection device 10 checks again whether the criterion is met: 3U0≥U set :

[0083] (a) If 3U0≥U set : i.e. 3U0 set This indicates that a transient single-phase ground fault occurred in collector line L4. After the fault occurred, collector line L4 automatically extinguished the arc and the insulation automatically recovered. At this time, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close, and the system grounding mode will switch from ungrounded operation to low-resistance grounding operation, and the system will return to normal. This judgment mode will greatly improve the stability of the system power supply.

[0084] (b) If 3U0≥U set This indicates that a permanent ground fault has occurred in collector line L4, and the integrated grounding protection device 10 will not execute the automatic closing command; at the same time, the integrated grounding protection device 10, according to the aforementioned criterion: 3I0≥I set 3I 02 ≥I set 3I 03 ≥I set This achieves precise line selection. At time t2, the integrated grounding protection device 10 disconnects the corresponding circuit breaker DL3, disconnects the corresponding collector line L4, and eliminates the grounding fault line. After the fault is cleared, 3U0... set At time t3, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close.

[0085] When the L4 grounding fault of the above-mentioned collector line is a permanent grounding fault, the corresponding DL circuit breaker and DL3 circuit breaker will both be disconnected, and the system will switch to ungrounded operation. At this time, the original single-phase grounding protection system has completely failed, but the integrated grounding protection device 10 can still work normally.

[0086] When circuit breakers DL and DL3 are disconnected (based on a ground fault in collector line L4), and a single-phase ground fault occurs again in the system, the criterion for selecting the fault location will be based on amplitude and phase comparison, thereby ensuring the ground fault is cleared. For example:

[0087] When a single-phase ground fault occurs in collector line L5, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 04 ≥I set -180°≤arg(3I) 04 ​​When the above criteria are met, the integrated grounding protection device 10 controls the DL4 circuit breaker to trip and disconnect the collector line L5.

[0088] When a single-phase ground fault occurs on other line L6, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 05 ≥I set -180°≤arg(3I) 05 When / 3U0)≤0°, the integrated grounding protection device 10 controls the DL5 circuit breaker to trip and disconnect other lines L6.

[0089] When a single-phase ground fault occurs on 35kV bus L1, the amplitude-phase ratio criterion is: 3U0≥U set 3I 01 ≥I set 3I 02 ≥I set 3I 04 ≥I set 3I 05 ≥I set -180°≤arg(3I) 01 / 3U0)≤0°、-180°≤arg(3I 02 / 3U0)≤0°, -180°≤arg(3I0 / 3U0)≤0°, -180°≤arg(3I 05 When the above criteria are met, the integrated grounding protection device 10 controls the DL1 circuit breaker, DL2 circuit breaker, DL4 circuit breaker, and DL5 circuit breaker to open and disconnect all lines.

[0090] (2) For a ground fault occurring in collector line L5, the following judgment and protection methods are available:

[0091] At time t1, 3U0≥U set 3I0≥I set 3I 02 ≥I se 3I 04 ≥I set The integrated grounding protection device 10 disconnects the DL circuit breaker, and the system switches from operating in the low-resistance grounding mode to operating in the ungrounded mode.

[0092] After time t1 to t2, the integrated grounding protection device 10 checks again whether the criterion is met: 3U0≥U set :

[0093] (a) If 3U0≥U set : i.e. 3U0 set ​This indicates that a transient single-phase ground fault occurred in collector line L5. After the fault occurred, collector line L5 automatically extinguished the arc and the insulation automatically recovered. At this time, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close, and the system grounding mode will switch from ungrounded operation to low-resistance grounding operation, and the system will return to normal. This judgment mode will greatly improve the stability of the system power supply.

[0094] (b) If 3U0≥U set This indicates that a permanent grounding fault has occurred in the collector line L5, and the integrated grounding protection device 10 will not execute the automatic closing command; at the same time, the integrated grounding protection device 10, according to the aforementioned criterion: 3I0≥I set 3I 02 ≥I se 3I 04 ≥I set This achieves precise line selection. At time t2, the integrated grounding protection device 10 disconnects the corresponding circuit breaker DL4, disconnects the corresponding collector line L5, and eliminates the grounding fault line. After the fault is cleared, 3U0... set At time t3, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close.

[0095] When the ground fault of the above-mentioned collector line L5 is a permanent ground fault, the corresponding DL circuit breaker and DL4 circuit breaker will both be disconnected, and the system will switch to ungrounded operation. At this time, the original single-phase ground fault protection system has completely failed, but the integrated ground fault protection device 10 can still work normally.

[0096] When the DL circuit breaker and DL4 circuit breaker are disconnected (based on a ground fault occurring in collector line L5), and a single-phase ground fault occurs again in the system, the criterion used for line selection will be amplitude and phase comparison, thereby ensuring the ground fault is cleared. For example:

[0097] When a single-phase ground fault occurs in collector line L4, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 03 ≥I set -180°≤arg(3I) 03 When the above criteria are met, the integrated grounding protection device 10 controls the DL3 circuit breaker to open and disconnect the collector line L4.

[0098] When a single-phase ground fault occurs on other line L6, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 05 ≥I set -180°≤arg(3I) 05 ​When the above criteria are met, the integrated grounding protection device 10 controls the DL5 circuit breaker to trip and disconnect other lines L6.

[0099] When a single-phase ground fault occurs on 35kV bus L1, the amplitude-phase ratio criterion is: 3U0≥U set 3I 01 ≥I set 3I 02 ≥I set 3I 03 ≥I set 3I 05 ≥I set -180 o ≤arg(3I 01 ) / (3U0)≤0 o -180°≤arg(3I) 02 ) / (3U0)≤0°、-180°≤arg(3I 03 ) / (3U0)≤0°、-180°≤arg(3I 05 When the above criteria are met, the integrated grounding protection device 10 controls the DL1 circuit breaker, DL2 circuit breaker, DL3 circuit breaker, and DL5 circuit breaker to open and disconnect all lines.

[0100] (3) For other lines L6 experiencing ground faults, the following judgment and protection methods apply:

[0101] At time t1, 3U0≥U set 3I0≥I set 3I 02 ≥I set 3I 05 ≥I set The integrated grounding protection device 10 disconnects the DL circuit breaker, and the system switches from operating in the low-resistance grounding mode to operating in the ungrounded mode.

[0102] After time t1 to t2, the integrated grounding protection device 10 checks again whether the criterion is met: 3U0≥U set :

[0103] (a) If 3U0≥U set : i.e. 3U0 set This indicates that the fault occurring on other line L6 is a transient single-phase ground fault. After the fault occurs, the arc on other line L6 is automatically extinguished and the insulation is automatically restored. At this time, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close, and the system grounding mode will switch from ungrounded operation to low-resistance grounding operation, and the system will return to normal. This judgment mode will greatly improve the stability of the system power supply.

[0104] ​(b) If 3U0≥U set This indicates that a permanent grounding fault has occurred on other line L6, and the integrated grounding protection device 10 will not execute the automatic closing command; at the same time, the integrated grounding protection device 10, based on the aforementioned criterion: 3I0≥I set 3I 02 ≥I set 3I 05 ≥I sett This achieves precise line selection. At time t2, the integrated grounding protection device 10 disconnects the corresponding circuit breaker DL5, disconnects the other line L6 corresponding to the grounding fault, and eliminates the grounding fault line. After the fault is cleared, 3U0... set At time t3, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close.

[0105] When the L6 grounding fault of the other lines mentioned above is a permanent grounding fault, the corresponding DL circuit breaker and DL5 circuit breaker will both be disconnected, and the system will switch to ungrounded operation. At this time, the original single-phase grounding protection system has completely failed, but the integrated grounding protection device 10 can still work normally.

[0106] When the DL and DL5 circuit breakers are disconnected (based on a ground fault occurring on line L6 in another line), and a single-phase ground fault occurs again in the system, the criterion for selecting the fault line will be based on amplitude and phase comparison, thereby ensuring the ground fault is cleared. For example:

[0107] When a single-phase ground fault occurs in collector line L4, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 03 ≥I set -180°≤arg(3I) 03 When the above criteria are met, the integrated grounding protection device 10 controls the DL3 circuit breaker to open and disconnect the collector line L4.

[0108] When a single-phase ground fault occurs in collector line L5, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 04 ≥I set -180°≤arg(3I) 04 When the above criteria are met, the integrated grounding protection device 10 controls the DL4 circuit breaker to open and disconnect the collector line L5.

[0109] When a single-phase ground fault occurs on 35kV bus L1, the amplitude-phase ratio criterion is: 3U0≥U set 3I 01 ≥I set 3I 02 ≥I set ​3I 03 ≥I set 3I 04 ≥I set -180°≤arg(3I) 01 ) / (3U0)≤0°、-180°≤arg(3I 02 ) / (3U0)≤0°、-180°≤arg(3I 03 ) / (3U0)≤0°、-180°≤arg(3I 04 When the above criteria are met, the integrated grounding protection device 10 controls the DL1 circuit breaker, DL2 circuit breaker, DL3 circuit breaker, and DL4 circuit breaker to open and disconnect all lines.

[0110] (4) Determine whether this type of fault has occurred based on the single-phase grounding fault judgment criteria for 35kV bus L1. The single-phase grounding fault judgment criteria for 35kV bus L1 are as follows:

[0111] At time t1, 3U0≥U set 3I0≥I set 3I 01 ≥I set 3I 02 ≥I set 3I 03 ≥I set 3I 04 ≥I set 3I 05 ≥I set ,

[0112] -180°≤arg(3I 01 ) / (3U0)≤0°、-180°≤arg(3I 02 ) / (3U0)≤0°、-180°≤arg(3I 03 ) / (3U0)≤0°、-180°≤arg(3I 04 ) / (3U0)≤0°、-180°≤arg(3I 05 ) / (3U0)≤0°, since most bus faults are permanent faults, the DL automatic closing command is not executed; at the same time, the integrated grounding protection device 10 can be used as a backup protection for bus protection, and at time t2, the DL1 circuit breaker, DL2 circuit breaker, DL3 circuit breaker, DL4 circuit breaker, and DL5 circuit breaker are disconnected.

[0113] (5) Determine whether this type of fault has occurred based on the ground fault determination criteria for L3 grounding line of the grounding transformer. The determination criteria for the L3 ground fault type of the grounding transformer line are as follows:

[0114] At time t1, 3U0≥Uset 3I0≥I set Since most grounding transformer line faults are permanent, the integrated grounding protection device 10 does not execute the DL automatic closing command; at time t2, the integrated grounding protection device 10 executes the DL2 opening command.

[0115] A phase-to-phase fault occurs in grounding transformer line L3: In this embodiment, the integrated grounding protection device 10 can determine whether this type of fault has occurred based on the phase-to-phase fault determination criteria for grounding transformer line L3. The determination criteria for the phase-to-phase fault type of grounding transformer line L3 are as follows:

[0116] At time t1, the phase current I A -I0≥I set or I B -I0≥I set or I C -I0≥I set (3I0=I) A +I B +I C (Calculated internally by the integrated grounding protection device 10), at time t2, the integrated grounding protection device 10 executes the DL2 trip command.

[0117] Mode 2: New energy power plants with voltage boosted by the main transformer are grounded via the neutral point resistance on the low-voltage side of the main transformer.

[0118] Figure 7 This is a schematic diagram of the grounding system structure for a new energy power station with voltage boosted by the main transformer and grounded via the neutral point resistance on the low-voltage side of the main transformer. Figure 7 The meanings of the physical parameters are as follows:

[0119] (1) L1 represents the 35kV bus, L2 represents the transmission line after being stepped up by the main transformer, L3 and L4 represent the collector line, L5 represents other lines, L6 represents the grounding resistance branch; the collector line can be one or more, and the number of the collector lines is not specifically limited in this embodiment. The number of modules is increased according to the number of the lines.

[0120] (2) PT, or voltage transformer, is installed on line L1, i.e., on the 35kV busbar, to detect the open delta voltage of the 35kV busbar, also known as the zero-sequence voltage of the 35kV busbar, which can be denoted as 3U0. This signal is transmitted to the analog signal interface A10; at the same time, the PT voltage transformer can also transmit the measured three-phase voltage on the 35kV busbar, denoted as U A U B U C Transmit the signal to the eighth analog signal interface A08.

[0121] (3) CT represents current transformer, which is used to measure line current; among which CT1 represents the first current transformer, CT2 represents the second current transformer, CT3 represents the third current transformer, and CT4 represents the fourth current transformer.

[0122] The first current transformer (zero-sequence current transformer) of CT1 is used to collect the zero-sequence current on the transmitting line L2, denoted as 3I. 01 The signal is transmitted to the first analog input signal interface A01.

[0123] The second current transformer (zero-sequence current transformer) of CT2 is used to collect the zero-sequence current on the collector line L3, denoted as 3I. 02 The signal is then transmitted to the second analog input signal interface A02.

[0124] The third current transformer (zero-sequence current transformer) of CT3 is used to collect the zero-sequence current on collector line L4, denoted as 3I. 03 The signal is then transmitted to the third analog input signal interface A03.

[0125] CT4, the fourth current transformer (zero-sequence current transformer), is used to collect the zero-sequence current on other lines L5, denoted as 3I. 04 The signal is then transmitted to the fourth analog input signal interface A04.

[0126] The CT current transformer (zero-sequence current transformer) is used to collect the zero-sequence current on the low-resistance line L6, denoted as 3I0, and transmits the signal to the ninth interface A09 of the analog input signal.

[0127] (4) DL represents a circuit breaker, used to open / close the line. When the circuit breaker is in the closed position, the line is connected; when the circuit breaker is in the open position, the line is disconnected. The opening and closing of the line is controlled by controlling the opening / closing state of the circuit breaker. Among them, DL represents a circuit breaker; DL1 represents the first circuit breaker, DL2 represents the second circuit breaker, DL3 represents the third circuit breaker, and DL4 represents the fourth circuit breaker.

[0128] The switching signal of the first circuit breaker of DL1 is transmitted to the first interface B01 of the switching signal input;

[0129] The switching signal of the second circuit breaker of DL2 is transmitted to the second interface B02 of the switching signal input;

[0130] The switching signal of the DL3 third circuit breaker is transmitted to the third interface B03 of the switching signal input;

[0131] The DL4 fourth circuit breaker's switching signal is transmitted to the fourth interface B04 of the switching signal input;

[0132] The DL circuit breaker's switching signal is transmitted to the tenth interface B10 of the switching signal input;

[0133] The opening / closing control circuit of the first circuit breaker of DL1 is transmitted to the first interface C01 of the switch signal output;

[0134] The DL2 second circuit breaker opening / closing control circuit transmits the switch signal output to the second interface C02;

[0135] The DL3 third circuit breaker opening / closing control circuit transmits the switch signal output to the third interface C03;

[0136] The DL4 fourth circuit breaker opening / closing control circuit transmits the switch signal output to the fourth interface C04;

[0137] The DL circuit breaker tripping control circuit transmits the digital signal output to the ninth interface C09.

[0138] The DL circuit breaker closing control circuit transmits the signal to the tenth interface C10 of the switch signal output.

[0139] (5) R represents the grounding small resistance, which is used in the small resistance grounding system. The system is grounded through this small resistance.

[0140] (6) GL represents a disconnecting switch, used to open / close the low-resistance branch of the grounding transformer. When the disconnecting switch is in the closed position, it means that the line is connected and the system operates in low-resistance grounding mode; when the disconnecting switch is in the open position, it means that the line is disconnected and the system operates in ungrounded mode.

[0141] (7) ZB represents the main transformer, which boosts the 35kV voltage to 110kV or 220kV. The low-voltage side is Y-connected to provide the neutral point. The line is led out from the neutral point and finally grounded through the GL disconnect switch, DL circuit breaker, small resistor R, and zero-sequence current transformer CT.

[0142] (8) 10- indicates a comprehensive grounding system protection device, used for grounding system protection and control; the comprehensive grounding protection device includes: an analog signal input module, a digital signal input module, an analog-to-digital conversion module, a logic judgment module, a digital signal output module, a mode conversion module, and a human-machine interaction module;

[0143] 9- indicates an automatic circuit breaker device used to open / close a grounding low-resistance line. When both automatic circuit breakers are in the closed position (i.e., both circuit breaker DL and disconnector GL are in the closed position), the grounding low-resistance line is in a conducting state, and the new energy power station operates in low-resistance grounding mode. When the automatic circuit breaker is in the open position, the grounding low-resistance line is in an open state, and the new energy power station operates in ungrounded mode.

[0144] 9- indicates an automatic circuit breaker device, which includes a disconnecting switch GL and a circuit breaker DL, used to control the on / off state of the grounding transformer branch L6, thereby achieving the switching of the grounding mode. The circuit breaker type is a vacuum circuit breaker or an SF6 circuit breaker.

[0145] Under Mode 2, the types of grounding faults involved are: grounding faults occurring in collector lines L3, L4, and other lines L5; grounding faults in 35kV bus L1; and grounding faults on the low-voltage side and leads of the main transformer.

[0146] (1) For a ground fault occurring in collector line L3, the following judgment and protection methods are available:

[0147] At time t1, 3U0≥U set 3I0≥I set 3I 01 ≥I set 3I 02 ≥I set The integrated grounding protection device 10 disconnects the DL circuit breaker, and the system switches from operating in the low-resistance grounding mode to operating in the ungrounded mode.

[0148] After time t1 to t2, the integrated grounding protection device 10 checks again whether the criterion is met: 3U0≥U set :

[0149] (a) If 3U0≥U set : i.e. 3U0 set This indicates that a transient single-phase ground fault occurred in collector line L3. After the fault occurred, collector line L3 automatically extinguished the arc and the insulation automatically recovered. At this time, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close, and the system grounding mode will switch from ungrounded operation to low-resistance grounding operation, and the system will return to normal. This judgment mode will greatly improve the stability of the system power supply.

[0150] (b) If 3U0≥U set This indicates that a permanent grounding fault has occurred in collector line L3, and the integrated grounding protection device 10 will not execute the automatic closing command; at the same time, the integrated grounding protection device 10, according to the aforementioned criterion: 3I0≥I set 3I 01 ≥I set 3I 02 ≥I set This achieves precise line selection. At time t2, the integrated grounding protection device 10 disconnects the corresponding circuit breaker DL2, disconnects the corresponding collector line L3 of the grounding fault, and eliminates the grounding fault line. After the fault is cleared, 3U0... set At time t3, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close. ​​

[0151] When the L3 grounding fault of the above-mentioned collector line is a permanent grounding fault, the corresponding DL circuit breaker and DL2 circuit breaker will both be disconnected, and the system will switch to ungrounded operation. At this time, the original single-phase grounding protection system has completely failed, but the integrated grounding protection device 10 can still work normally.

[0152] When circuit breakers DL and DL2 are disconnected (based on a ground fault in collector line L3), and a single-phase ground fault occurs again in the system, the criterion for fault selection will be amplitude and phase comparison, thereby ensuring the ground fault is cleared. For example:

[0153] When a single-phase ground fault occurs in collector line L4, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 03 ≥I set -180°≤arg(3I) 03 When the above criteria are met, the integrated grounding protection device 10 controls the DL3 circuit breaker to open and disconnect the collector line L4.

[0154] When a single-phase ground fault occurs on other line L5, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 04 ≥I set -180°≤arg(3I) 04 When the above criteria are met, the integrated grounding protection device 10 controls the DL4 circuit breaker to trip and disconnect the other line L5.

[0155] When a single-phase ground fault occurs on 35kV bus L1, the amplitude-phase ratio criterion is: 3U0≥U set 3I 01 ≥I set 3I 03 ≥I set 3I 04 ≥I set -180°≤arg(3I) 01 ) / (3U0)≤0°、-180°≤arg(3I 03 ) / (3U0)≤0°、-180°≤arg(3I 04 When the above criteria are met, the integrated grounding protection device 10 controls the DL1 circuit breaker, DL3 circuit breaker, and DL4 circuit breaker to open and disconnect all lines.

[0156] (2) For a ground fault occurring in collector line L4, the following judgment and protection methods are available:

[0157] At time t1, 3U0≥Uset 3I0≥I set、 3I 01 ≥I set 3I 03 ≥I set At this time, the zero-sequence voltage exceeds the limit, and the integrated grounding protection device 10 disconnects the DL circuit breaker, and the system switches from operating in the small resistance grounding mode to operating in the ungrounded mode;

[0158] After time t1 to t2, the integrated grounding protection device 10 checks again whether the criterion is met: 3U0≥U set :

[0159] (a) If 3U0≥U set : i.e. 3U0 set This indicates that a transient single-phase ground fault occurred in collector line L4. After the fault occurred, collector line L4 automatically extinguished the arc and the insulation automatically recovered. At this time, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close, and the system grounding mode will switch from ungrounded operation to low-resistance grounding operation, and the system will return to normal. This judgment mode will greatly improve the stability of the system power supply.

[0160] (b) If 3U0≥U set This indicates that a permanent ground fault has occurred in collector line L4, and the integrated grounding protection device 10 will not execute the automatic closing command; at the same time, the integrated grounding protection device 10, according to the aforementioned criterion: 3I0≥I set 3I 01 ≥I set 3I 03 ≥I set This achieves precise line selection. At time t2, the integrated grounding protection device 10 disconnects the corresponding circuit breaker DL3, disconnects the corresponding collector line L4, and eliminates the grounding fault line. After the fault is cleared, 3U0... set At time t3, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close.

[0161] When the L4 grounding fault of the above-mentioned collector line is a permanent grounding fault, the corresponding DL circuit breaker and DL3 circuit breaker will both be disconnected, and the system will switch to ungrounded operation. At this time, the original single-phase grounding protection system has completely failed, but the integrated grounding protection device 10 can still work normally.

[0162] When circuit breakers DL and DL3 are disconnected (based on a ground fault in collector line L4), and a single-phase ground fault occurs again in the system, the criterion for selecting the fault location will be based on amplitude and phase comparison, thereby ensuring the ground fault is cleared. For example:

[0163] ​​When a single-phase ground fault occurs in collector line L3, the amplitude-phase comparison criterion is: 3U0≥U set 3I 02 ≥I set -180°≤arg(3I) 02 When the above criteria are met, the integrated grounding protection device 10 controls the DL2 circuit breaker to open and disconnect the collector line L3.

[0164] When a single-phase ground fault occurs on other line L5, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 04 ≥I set -180°≤arg(3I) 04 When the above criteria are met, the integrated grounding protection device 10 controls the DL4 circuit breaker to trip and disconnect the other line L5.

[0165] When a single-phase ground fault occurs on 35kV bus L1, the amplitude-phase ratio criterion is: 3U0≥U set 3I 01 ≥I set 3I 02 ≥I set 3I 04 ≥I set -180°≤arg(3I) 01 ) / (3U0)≤0°、-180°≤arg(3I 02 ) / (3U0)≤0°、-180°≤arg(3I 04 When the above criteria are met, the integrated grounding protection device 10 controls the DL1 circuit breaker, DL2 circuit breaker, and DL4 circuit breaker to open and disconnect all lines.

[0166] (3) If a ground fault occurs on other lines L5, the following judgment and protection methods shall be used:

[0167] At time t1, 3U0≥U set 3I0≥I set 3I 01 ≥I set 3I 04 ≥I set At this time, the zero-sequence voltage exceeds the limit, and the integrated grounding protection device 10 disconnects the DL circuit breaker, and the system switches from operating in the small resistance grounding mode to operating in the ungrounded mode;

[0168] After time t1 to t2, the integrated grounding protection device 10 checks again whether the criterion is met: 3U0≥U set :

[0169] (a) If 3U0≥U set : i.e. 3U0 set This indicates that the fault occurring on other line L5 is a transient single-phase ground fault. After the fault occurs, the arc on other line L5 is automatically extinguished and the insulation is automatically restored. At this time, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close, and the system grounding mode will switch from ungrounded operation to low-resistance grounding operation, and the system will return to normal. This judgment mode will greatly improve the stability of the system power supply.

[0170] (b) If 3U0≥U set This indicates that a permanent grounding fault has occurred on other line L5, and the integrated grounding protection device 10 will not execute the automatic closing command; at the same time, the integrated grounding protection device 10, based on the aforementioned criterion: 3I0≥I set 3I 01 ≥I set 3I 04 ≥I sett This achieves precise line selection. At time t2, the integrated grounding protection device 10 disconnects the corresponding circuit breaker DL4, disconnects the other line L5 corresponding to the grounding fault, and eliminates the grounding fault line. After the fault is cleared, 3U0... set At time t3, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close.

[0171] When the L5 grounding fault of the other lines mentioned above is a permanent grounding fault, the corresponding DL circuit breaker and DL4 circuit breaker will both be disconnected, and the system will switch to ungrounded operation. At this time, the original single-phase grounding protection system has completely failed, but the integrated grounding protection device 10 can still work normally.

[0172] When circuit breakers DL and DL4 are disconnected (assuming a ground fault has occurred on line L5), and a single-phase ground fault occurs again in the system, the criterion for selecting the fault location will be based on amplitude and phase comparison, thereby clearing the ground fault. For example:

[0173] When a single-phase ground fault occurs in collector line L3, the amplitude-phase comparison criterion is: 3U0≥U set 3I 02 ≥I set -180°≤arg(3I) 02 When the above criteria are met, the integrated grounding protection device 10 controls the DL2 circuit breaker to open and disconnect the collector line L3.

[0174] When a single-phase ground fault occurs in collector line L4, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 03 ≥I set -180°≤arg(3I)​​03 When the above criteria are met, the integrated grounding protection device 10 controls the DL3 circuit breaker to open and disconnect the collector line L4.

[0175] When a single-phase ground fault occurs on 35kV bus L1, the amplitude-phase ratio criterion is: 3U0≥U set 3I 02 ≥I set 3I 03 >I set -180°≤arg(3I) 01 ) / (3U0)≤0°、-180°≤arg(3I 02 ) / (3U0)≤0°、-180°≤arg(3I 03 When the above criteria are met, the integrated grounding protection device 10 controls the DL1 circuit breaker, DL2 circuit breaker, and DL3 circuit breaker to open and disconnect all lines.

[0176] (4) If a ground fault occurs on other lines L5, the following judgment and protection methods shall be used:

[0177] The integrated grounding protection device 10 can determine whether a single-phase grounding fault has occurred based on the criteria for determining a single-phase grounding fault on the 35kV busbar L1. The criteria for determining a single-phase grounding fault on the 35kV busbar L1 are as follows:

[0178] At time t1, 3U0≥U set 3I0≥I set 3I 01 ≥I set 3I 02 ≥I set 3I 03 ≥I set 3I 04 ≥I set -180°≤arg(3I) 01 ) / (3U0)≤0°、-180°≤arg(3I 02 ) / (3U0)≤0°、-180°≤arg(3I 03 ) / (3U0)≤0°、-180°≤arg(3I 04 Since most bus faults are permanent, the integrated grounding protection device 10 does not execute the DL automatic closing command. At the same time, the integrated grounding protection device 10 can be used as a backup protection for bus protection. At time t2, the DL1 circuit breaker, DL2 circuit breaker, DL3 circuit breaker and DL4 circuit breaker are disconnected.

[0179] (5) A single-phase ground fault occurs on the low-voltage side of the main transformer, and the fault is cleared by the differential protection of the main transformer.

[0180] Mode 3: New energy power plants with voltage boosted by the main transformer are grounded via a grounding transformer with low resistance.

[0181] Figure 8 This is a schematic diagram of the grounding system protection for a new energy power station with voltage boosted by the main transformer and grounded through a grounding transformer with reduced resistance. Figure 8 The physical parameters in the text have the following meanings:

[0182] (1) L1 represents the 35kV bus, L2 represents the transmission line after the main transformer step-up, L3 represents the grounding transformer line, L4 represents the collector line, L5 represents the collector line; L6 represents the grounding small resistance branch; the collector line can be one or more, and the number of the collector lines is not specifically limited in this embodiment. The number of the modules is increased according to the number of the lines.

[0183] (2) PT, or voltage transformer, is installed on line L1, i.e., on the 35kV busbar, to detect the open delta voltage of the 35kV busbar, also known as the zero-sequence voltage of the 35kV busbar, which can be denoted as 3U0. This signal is transmitted to the analog signal interface A10; at the same time, the PT voltage transformer can also transmit the measured three-phase voltage on the 35kV busbar, denoted as U A U B U C Transmit the signal to the eighth analog signal interface A08.

[0184] (3) T represents a Z-type grounding transformer, from which a neutral line is drawn.

[0185] (4) CT represents current transformer, which is used to measure line current; among which CT1 represents the first current transformer, CT2 represents the second current transformer, CT3 represents the third current transformer, and CT4 represents the fourth current transformer.

[0186] The first current transformer (zero-sequence current transformer) of CT1 is used to collect the zero-sequence current on the transmitting line L2, denoted as 3I. 01 The signal is transmitted to the first analog input signal interface A01.

[0187] The second current transformer (zero-sequence current transformer) of CT2 is used to collect the zero-sequence current on the grounding transformer line L3, denoted as 3I. 02 The signal is then transmitted to the second analog input signal interface A02.

[0188] The third current transformer (zero-sequence current transformer) of CT3 is used to collect the zero-sequence current on collector line L4, denoted as 3I. 03 The signal is then transmitted to the third analog input signal interface A03.

[0189] The fourth current transformer (zero-sequence current transformer) CT4 is used to collect the zero-sequence current on collector line L5, denoted as 3I. 04 The signal is then transmitted to the fourth analog input signal interface A04.

[0190] The CT5 current transformer is used to collect the three-phase current on the grounding transformer line L3, denoted as I. A I B I C The signal is then transmitted to the fifth analog input signal interface A05.

[0191] The CT current transformer (zero-sequence current transformer) is used to collect the zero-sequence current on the low-resistance line L6, denoted as 3I0, and transmits the signal to the ninth interface A09 of the analog input signal.

[0192] (5) DL represents a circuit breaker, used to open / close the line. When the circuit breaker is in the closed position, the line is connected; when the circuit breaker is in the open position, the line is disconnected. The opening and closing of the line is controlled by controlling the opening / closing state of the circuit breaker. Among them, DL represents a circuit breaker; DL1 represents the first circuit breaker, DL2 represents the second circuit breaker, DL3 represents the third circuit breaker, and DL4 represents the fourth circuit breaker.

[0193] The switching signal of the first circuit breaker of DL1 is transmitted to the first interface B01 of the switching signal input;

[0194] The switching signal of the second circuit breaker of DL2 is transmitted to the second interface B02 of the switching signal input;

[0195] The switching signal of the DL3 third circuit breaker is transmitted to the third interface B03 of the switching signal input;

[0196] The DL4 fourth circuit breaker's switching signal is transmitted to the fourth interface B04 of the switching signal input;

[0197] The DL circuit breaker's switching signal is transmitted to the tenth interface B10 of the switching signal input;

[0198] The opening / closing control circuit of the first circuit breaker of DL1 is transmitted to the first interface C01 of the switch signal output;

[0199] The DL2 second circuit breaker opening / closing control circuit transmits the switch signal output to the second interface C02;

[0200] The DL3 third circuit breaker opening / closing control circuit transmits the switch signal output to the third interface C03;

[0201] The DL4 fourth circuit breaker opening / closing control circuit transmits the switch signal output to the fourth interface C04;

[0202] The DL circuit breaker tripping control circuit transmits the digital signal output to the ninth interface C09.

[0203] The DL circuit breaker closing control circuit transmits the signal to the tenth interface C10 of the switch signal output.

[0204] (6) R represents the grounding small resistance, which is used in the small resistance grounding system. The system is grounded through this small resistance.

[0205] (7) GL represents a disconnecting switch, used to open / close the low-resistance branch of the grounding transformer. When the disconnecting switch is in the closed position, it means that the line is connected and the system operates in low-resistance grounding mode; when the disconnecting switch is in the open position, it means that the line is disconnected and the system operates in ungrounded mode.

[0206] (8) ZB represents the main transformer, which steps up the 35kV voltage to 110kV or 220kV. The high voltage side is Y-connected and the low voltage side is delta-connected.

[0207] (9) JDB represents the grounding transformer. The high-voltage side of the grounding transformer is connected in a Z-type configuration. A neutral line is drawn out from the neutral point on the high-voltage side to provide an artificial neutral point. Grounding is achieved through GL disconnect switch, DL circuit breaker, R small resistor, and CT zero-sequence current transformer.

[0208] (10) 10- indicates a comprehensive grounding system protection device, used for grounding system protection and control; the comprehensive grounding protection device includes: an analog signal input module, a digital signal input module, an analog-to-digital conversion module, a logic judgment module, a digital signal output module, a mode conversion module, and a human-machine interaction module;

[0209] 9- indicates an automatic circuit breaker device used to open / close a grounding low-resistance line. When both automatic circuit breakers are in the closed position (i.e., both circuit breaker DL and disconnector GL are in the closed position), the grounding low-resistance line is in a conducting state, and the new energy power station operates in low-resistance grounding mode. When the automatic circuit breaker is in the open position, the grounding low-resistance line is in an open state, and the new energy power station operates in ungrounded mode.

[0210] 9- indicates an automatic circuit breaker device, which includes a disconnecting switch GL and a circuit breaker DL, used to control the on / off state of the grounding transformer branch L6, thereby achieving the switching of the grounding mode. The circuit breaker type is a vacuum circuit breaker or an SF6 circuit breaker.

[0211] Under Mode 3, the types of grounding faults involved are: grounding faults occurring in collector lines L4 and L5; grounding faults occurring in 35kV bus L1; and grounding and phase-to-phase faults occurring in grounding transformer line L3.

[0212] (1) When a ground fault occurs in collector line L4, the following judgment and protection methods are available:

[0213] At time t1, 3U0≥U set 3I0≥I set 3I 02 ≥I set 3I 03 ≥I set At this time, the zero-sequence voltage exceeds the limit, and the integrated grounding protection device 10 disconnects the DL circuit breaker, and the system switches from operating in the small resistance grounding mode to operating in the ungrounded mode;

[0214] After time t1 to t2, the integrated grounding protection device 10 checks again whether the criterion is met: 3U0≥U set :

[0215] (a) If 3U0≥U set : i.e. 3U0 set This indicates that a transient single-phase ground fault occurred in collector line L4. After the fault occurred, collector line L4 automatically extinguished the arc and the insulation automatically recovered. At this time, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close, and the system grounding mode will switch from ungrounded operation to low-resistance grounding operation, and the system will return to normal. This judgment mode will greatly improve the stability of the system power supply.

[0216] (b) If 3U0≥U set This indicates that a permanent ground fault has occurred in collector line L4, and the integrated grounding protection device 10 will not execute the automatic closing command; at the same time, the integrated grounding protection device 10, according to the aforementioned criterion: 3I0≥I set 3I 02 ≥I set 3I 03 ≥I set This achieves precise line selection. At time t2, the integrated grounding protection device 10 disconnects the corresponding circuit breaker DL3, disconnects the corresponding collector line L4, and eliminates the grounding fault line. After the fault is cleared, 3U0... set， At time t3, the integrated grounding protection device 10 will control the DL circuit breaker to close automatically.

[0217] When the L4 grounding fault of the above-mentioned collector line is a permanent grounding fault, the corresponding DL circuit breaker and DL3 circuit breaker will both be disconnected, and the system will switch to ungrounded operation. At this time, the original single-phase grounding protection system has completely failed, but the integrated grounding protection device 10 can still work normally.

[0218] When circuit breakers DL and DL3 are disconnected (based on a ground fault in collector line L4), and a single-phase ground fault occurs again in the system, the criterion for selecting the fault location will be based on amplitude and phase comparison, thereby ensuring the ground fault is cleared. For example: ​​

[0219] When a single-phase ground fault occurs in collector line L5, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 04 ≥I set -180°≤arg(3I) 04 / (3U0)≤0°, when the above criteria are met, the integrated grounding protection device 10 controls the DL4 circuit breaker to open and disconnect the collector line L5.

[0220] When a single-phase ground fault occurs in grounding transformer line L3, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 02 ≥I set -180°≤arg(3I) 02 / (3U0)≤0°, when the above criteria are met, the integrated grounding protection device 10 controls the DL2 circuit breaker to open and disconnect the grounding transformer line L3.

[0221] When a single-phase ground fault occurs on 35kV bus L1, the amplitude-phase ratio criterion is: 3U0≥U set 3I 01 ≥I set 3I 02 ≥I set 3I 04 ≥I set -180 o ≤arg(3I 01 ) / (3U0)≤0 o -180°≤arg(3I) 02 / (3U0)≤0°、-180°≤arg(3I 03 When / (3U0)≤0°, the integrated grounding protection device 10 controls the DL1 circuit breaker, DL2 circuit breaker and DL4 circuit breaker to open and disconnect all lines.

[0222] (2) When a ground fault occurs in collector line L5, the following judgment and protection methods are available:

[0223] At time t1, 3U0≥U set 3I0≥I set 3I 02 ≥I set、 3I 04 ≥I set At this time, the zero-sequence voltage exceeds the limit, and the integrated grounding protection device 10 disconnects the DL circuit breaker, and the system switches from operating in the small resistance grounding mode to operating in the ungrounded mode;

[0224] After time t1 to t2, the integrated grounding protection device 10 checks again whether the criterion is met: 3U0≥U set :

[0225] (a) If 3U0≥U set : i.e. 3U0 set This indicates that a transient single-phase ground fault occurred in collector line L5. After the fault occurred, collector line L5 automatically extinguished the arc and the insulation automatically recovered. At this time, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close, and the system grounding mode will switch from ungrounded operation to low-resistance grounding operation, and the system will return to normal. This judgment mode will greatly improve the stability of the system power supply.

[0226] (b) If 3U0≥U set This indicates that a permanent grounding fault has occurred in collector line L5, and the integrated grounding protection device 10 will not execute the automatic closing command; at the same time, the integrated grounding protection device 10, according to the aforementioned criterion: 3I0=3I 02 =3I 04 ≥I set This achieves precise line selection. At time t2, the integrated grounding protection device 10 disconnects the corresponding circuit breaker DL4, disconnects the corresponding collector line L5, and eliminates the grounding fault line. After the fault is cleared, 3U0... set At time t3, the integrated grounding protection device 10 will control the DL circuit breaker to automatically close.

[0227] When the ground fault of the above-mentioned collector line L5 is a permanent ground fault, the corresponding DL circuit breaker and DL4 circuit breaker will both be disconnected, and the system will switch to ungrounded operation. At this time, the original single-phase ground fault protection system has completely failed, but the integrated ground fault protection device 10 can still work normally.

[0228] When circuit breakers DL and DL4 are disconnected (based on a ground fault occurring in collector line L5), and a single-phase ground fault occurs again in the system, the criterion for selecting the fault location will be based on amplitude and phase comparison, thereby ensuring the ground fault is cleared. For example:

[0229] When a single-phase ground fault occurs in collector line L4, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 03 ≥I set -180°≤arg(3I) 03 When / (3U0)≤0°, the integrated grounding protection device 10 controls the DL3 circuit breaker to open and disconnect the collector line L4 when the above criteria are met.

[0230] When a single-phase ground fault occurs in grounding transformer line L3, the amplitude-phase comparison criterion is: 3U0 ≥ U set 3I 02 ≥I set -180°≤arg(3I)​​02 / (3U0)≤0°, when the above criteria are met, the integrated grounding protection device 10 controls the DL2 circuit breaker to open and disconnect the grounding transformer line L3.

[0231] When a single-phase ground fault occurs on 35kV bus L1, the amplitude-phase ratio criterion is: 3U0≥U set 3I 01 ≥I set 3I 02 ≥I set 3I 03 ≥I set -180°≤arg(3I) 01 ) / (3U0)≤0°、-180°≤arg(3I 02 ) / (3U0)≤0°、-180°≤arg(3I 03 When the above criteria are met, the integrated grounding protection device 10 controls the DL1 circuit breaker, DL2 circuit breaker, and DL3 circuit breaker to disconnect all lines.

[0232] (3) For a single-phase ground fault on the 35kV busbar L1, the following judgment and protection methods are available:

[0233] The integrated grounding protection device 10 can determine whether a single-phase grounding fault has occurred based on the criteria for determining a single-phase grounding fault on the 35kV busbar L1. The criteria for determining a single-phase grounding fault on the 35kV busbar L1 are as follows:

[0234] At time t1, 3U0≥U set 3I0≥I set 3I 01 ≥I set 3I 02 ≥I set 3I 03 ≥I set 3I 04 ≥I set -180°≤arg(3I) 01 ) / (3U0)≤0°、-180°≤arg(3I 02 ) / (3U0)≤0°、-180°≤arg(3I 03 ) / (3U0)≤0°、-180°≤arg(3I 04 Since most bus faults are permanent, the integrated grounding protection device 10 does not execute the DL automatic closing command. At the same time, the integrated grounding protection device 10 can be used as a backup protection for bus protection. At time t2, the DL1 circuit breaker, DL2 circuit breaker, DL3 circuit breaker and DL4 circuit breaker are disconnected.

[0235] (4) When a ground fault occurs in line L3 of the grounding transformer, the following judgment and protection methods apply:

[0236] The integrated grounding protection device 10 can determine whether a grounding fault of type L3 has occurred based on the grounding fault determination criteria for grounding transformer line L3. The determination criteria for grounding fault type L3 of grounding transformer line are as follows:

[0237] At time t1, 3U0≥U set 3I0≥I set Since most grounding transformer line faults are permanent, the integrated grounding protection device 10 does not execute the DL automatic closing command; at time t2, the integrated grounding protection device 10 executes the DL2 opening command.

[0238] (5) When a phase-to-phase fault occurs in line L3 of the grounding transformer, the following judgment and protection methods are available:

[0239] The integrated grounding protection device 10 can determine whether a fault of this type has occurred based on the fault determination criteria for phase-to-phase L3 of the grounding transformer line. The determination criteria for phase-to-phase L3 faults of the grounding transformer line are as follows:

[0240] At time t1, the phase current I A -I0≥I set or I B -I0≥I set or I C -I0≥I set (3I0=I) A +I B +I C, (Calculated internally by the integrated grounding protection device 10), at time t2, the integrated grounding protection device 10 executes the DL2 trip command.

[0241] The integrated grounding protection device in this embodiment is presented in the form of a functional unit. Here, a unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0242] This invention also provides a computer device having the integrated grounding protection device described above.

[0243] Please see Figure 9 , Figure 9 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 9As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 9 Take a processor 10 as an example.

[0244] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0245] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0246] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0247] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0248] The computer device also includes an input device 30 and an output device 40. The processor 10, memory 20, input device 30, and output device 40 can be connected via a bus or other means. Figure 9 Taking the example of a connection between China and Israel via a bus.

[0249] Input device 30 can receive input numerical or character information, and generate key signal inputs related to user settings and function control of the computer device, such as a touchscreen, keypad, mouse, trackpad, touchpad, joystick, one or more mouse buttons, trackball, joystick, etc. Output device 40 may include display devices, auxiliary lighting devices (e.g., LEDs), and haptic feedback devices (e.g., vibration motors). The aforementioned display devices include, but are not limited to, liquid crystal displays, light-emitting diodes, displays, and plasma displays. In some alternative embodiments, the display device may be a touchscreen.

[0250] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0251] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0252] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A comprehensive protection system for single-phase grounding faults in a new energy power plant, characterized in that, include: Line telemetry module, integrated grounding protection equipment, automatic circuit breaker device, among which, The line telemetry module is used to detect the current and voltage of each line in the power station; The integrated grounding protection device is used to switch to the corresponding mode according to the neutral point setting method of the power station; based on the current and voltage of each line and the opening and closing position status of the power station circuit breaker, it performs logical operations to determine whether a grounding fault has occurred; and issues a corresponding control signal according to the determination result. The automatic circuit breaker device is connected in series with the grounding branch of the power station. When the automatic circuit breaker device receives the control signal, it closes or opens to realize the operation of the power station in grounded or ungrounded mode. The operating modes include: grounding mode of new energy power stations without main transformer step-up via grounding transformer with reduced resistance, grounding mode of new energy power stations with main transformer step-up via main transformer low-voltage side neutral point resistance, and grounding mode of new energy power stations with main transformer step-up via grounding transformer with reduced resistance. The power station includes collector lines, grounding lines, grounding transformer branches, transmission lines, busbars and other lines; For any collector line, the process of issuing the corresponding control signal based on the judgment result includes: When the operating mode is a new energy power station without main transformer step-up and grounded through a grounding transformer with low resistance, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of the collector line is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breaker on the collector line is controlled to open; otherwise, the automatic circuit breaker device is controlled to close. When the operating mode is the new energy power station with voltage boosted by the main transformer and grounded through the neutral point resistance of the low-voltage side of the main transformer, if the amplitude of the zero-sequence voltage of the bus is greater than or equal to the preset bus voltage threshold, the amplitude of the zero-sequence current on the grounding line is greater than or equal to the preset grounding current threshold, the amplitude of the zero-sequence current of the transmitting line is greater than or equal to the preset grounding transformer current threshold, and the amplitude of the zero-sequence current of the collector line is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the amplitude of the zero-sequence voltage of the bus is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breaker on the collector line is controlled to open; otherwise, the automatic circuit breaker device is controlled to close. When the operating mode is the new energy power station with voltage boosted by the main transformer and grounded through the grounding transformer with low resistance, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of the collector line is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breaker on the collector line is controlled to open; otherwise, the automatic circuit breaker device is controlled to close.

2. The integrated protection system for single-phase grounding faults in new energy power plants according to claim 1, characterized in that, The integrated grounding protection device includes: an analog signal input module, a digital signal input module, an analog-to-digital conversion module, a logic judgment module, a digital signal output module, a mode conversion module, and a human-machine interaction module. The analog signal input module is used to acquire the current and voltage signals of the current transformer and voltage transformer, and transmit the current and voltage signals to the analog-to-digital conversion module; The switch signal input module is used to collect the circuit breaker opening and closing position status of the corresponding circuit breaker and transmit the circuit breaker opening and closing position status to the logic judgment module. The analog-to-digital converter module is used to convert the analog signal from the analog signal input module into a digital signal, and transmit the digital signal to the logic judgment module; The logic judgment module compares the amplitude and phase of the current and voltage of each line obtained by the line telemetry module, and combines the circuit breaker opening and closing position status to determine whether a ground fault has occurred through logic calculation. The switch signal output module is used to receive the logic judgment result of the logic judgment module and to output the corresponding circuit breaker control signal. The mode conversion module is used to switch the working mode of the integrated grounding protection device according to the neutral point setting method of the power station. The human-computer interaction module is used for manual control and searching of the system's operating status. At the same time, staff can use the human-computer interaction module to switch the working modes of the mode conversion module.

3. A comprehensive protection method for single-phase grounding faults in new energy power plants, characterized in that, The method, applied to the integrated grounding protection device of claim 1, comprises: The current and voltage of each line in the power station are obtained from the remote sensing module. Switch to the corresponding mode according to the neutral point setting method of the power station; Based on the amplitude and phase of the current and voltage of each line and the opening and closing position of the circuit breaker of the power station, a ground fault is determined through logical operation, and a corresponding control signal is issued according to the determination result. The control signal is used to control the automatic circuit breaker device to close or open, so as to realize the operation of the power station in grounded or ungrounded mode; The power station includes collector lines, grounding lines, grounding transformer branches, transmission lines, busbars and other lines; For any collector line, the process of issuing the corresponding control signal based on the judgment result includes: When the operating mode is a new energy power station without main transformer step-up and grounded through a grounding transformer with low resistance, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of the collector line is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breaker on the collector line is controlled to open; otherwise, the automatic circuit breaker device is controlled to close. When the operating mode is the new energy power station with voltage boosted by the main transformer and grounded through the neutral point resistance of the low-voltage side of the main transformer, if the amplitude of the zero-sequence voltage of the bus is greater than or equal to the preset bus voltage threshold, the amplitude of the zero-sequence current on the grounding line is greater than or equal to the preset grounding current threshold, the amplitude of the zero-sequence current of the transmitting line is greater than or equal to the preset grounding transformer current threshold, and the amplitude of the zero-sequence current of the collector line is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the amplitude of the zero-sequence voltage of the bus is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breaker on the collector line is controlled to open; otherwise, the automatic circuit breaker device is controlled to close. When the operating mode is the new energy power station with voltage boosted by the main transformer and grounded through the grounding transformer with low resistance, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of the collector line is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breaker on the collector line is controlled to open; otherwise, the automatic circuit breaker device is controlled to close.

4. The comprehensive protection method for single-phase grounding faults in new energy power plants according to claim 3, characterized in that, When at least one collector line experiences a permanent single-phase ground fault, the process of issuing a corresponding control signal based on the judgment result further includes: For any unfaulted collector line, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude of the collector line is greater than or equal to the preset collector line current threshold, and the phase angle of the collector line is greater than or equal to -180° and less than or equal to 0°, then the circuit breaker on the collector line is controlled to open. For any other line, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude of the other line is greater than or equal to the preset current threshold of the other line, and the phase angle of the other line is greater than or equal to -180° and less than or equal to 0°, then the circuit breaker on that other line is controlled to open.

5. The comprehensive protection method for single-phase grounding faults in new energy power plants according to any one of claims 3 or 4, characterized in that, The process of issuing corresponding control signals based on the judgment result further includes: If the zero-sequence voltage amplitude of the busbar is greater than or equal to the preset busbar voltage threshold, the zero-sequence current amplitude of the transmitting line is greater than or equal to the preset transmitting line current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of all collector lines is greater than or equal to the collector line current threshold, and at the same time the phase angle of the transmitting line, the grounding transformer branch, and all collector lines is greater than or equal to -180° and less than or equal to 0°, then the circuit breakers on the transmitting line, the grounding transformer branch, and all collector lines will be opened.

6. The comprehensive protection method for single-phase grounding faults in new energy power plants according to claim 3, characterized in that, For any other line, the process of issuing the corresponding control signal based on the judgment result includes: When the operating mode is a new energy power station without main transformer step-up and grounded through a grounding transformer with low resistance, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of other lines is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the bus zero-sequence voltage amplitude is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breakers on the other lines are controlled to open; otherwise, the automatic circuit breaker device is controlled to close. When the operating mode is the new energy power station with voltage boosted by the main transformer and grounded through the neutral point resistance of the low-voltage side of the main transformer, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude of the transmitting line is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of other lines is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breakers on the other lines are controlled to open; otherwise, the automatic circuit breaker device is controlled to close. When the operating mode is the new energy power station with voltage boosted by the main transformer and grounded by the grounding transformer with low resistance, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of other lines is greater than or equal to the preset collector line current threshold, then the automatic circuit breaker device is controlled to open; after a preset time, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, then the automatic circuit breaker device is controlled to remain in the open state, and the circuit breakers on the other lines are controlled to open; otherwise, the automatic circuit breaker device is controlled to close.

7. The comprehensive protection method for single-phase grounding faults in new energy power plants according to claim 3, characterized in that, When at least one other line experiences a permanent single-phase ground fault, the process of issuing a corresponding control signal based on the judgment result further includes: For any collector line, if the zero-sequence voltage amplitude of the bus is greater than or equal to the preset bus voltage threshold, the zero-sequence current amplitude of the collector line is greater than or equal to the preset collector line current threshold, and the phase angle of the collector line is greater than or equal to -180° and less than or equal to 0°, then the circuit breaker on the collector line is controlled to open.

8. The comprehensive protection method for single-phase grounding faults in new energy power plants according to any one of claims 6 or 7, characterized in that, The process of issuing corresponding control signals based on the judgment result further includes: If the zero-sequence voltage amplitude of the busbar is greater than or equal to the preset busbar voltage threshold, the zero-sequence current amplitude of the transmitting line is greater than or equal to the preset transmitting line current threshold, the zero-sequence current amplitude of the grounding transformer branch is greater than or equal to the preset grounding transformer current threshold, and the zero-sequence current amplitude of all collector lines is greater than or equal to the collector line current threshold, and at the same time the phase angle of the transmitting line, the grounding transformer branch, and all collector lines is greater than or equal to -180° and less than or equal to 0°, then the circuit breakers on the transmitting line, the grounding transformer branch, and all collector lines will be opened.

9. The comprehensive protection method for single-phase grounding faults in new energy power plants according to claim 3, characterized in that, For grounding transformer lines, the process of issuing corresponding control signals based on the judgment result includes: If the zero-sequence voltage amplitude of the busbar is greater than or equal to the preset busbar voltage threshold, and the zero-sequence current amplitude on the grounding line is greater than or equal to the preset grounding current threshold, then the automatic circuit breaker device is controlled to remain in the open state. After a preset time, the circuit breaker on the grounding transformer line is controlled to open. If the difference between the amplitude of any phase current of the busbar and the amplitude of its zero-sequence current is greater than or equal to the preset current difference, the circuit breaker on the grounding transformer line will be controlled to trip.

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