Ground fault current regulation and control system, method and equipment and storage medium

Abstract

The embodiment of the invention discloses a ground fault current regulation and control system, method and device and a storage medium, the system is composed of a converter and a low-cost rapid mechanical switch, the switch branch current of the to-be-switched rapid mechanical switch is inhibited to be zero through an arc-free tapping method, and then rapid arc-free tapping conversion is realized. The problem that the adjustment response speed is low is effectively solved.

Description

[Technical field]

[0001] The present invention relates to the technical field of single-phase ground fault control in distribution network, and in particular to a ground fault current control system, method, device and storage medium. [Background technology]

[0002] During the operation of the distribution network, there are a large number of single-phase grounding faults caused by complex reasons such as lightning strikes, short-term contact between branches and conductors, insulator contamination and breakdown, and cable degradation. Low-current grounding methods, especially resonant grounding methods, have the advantages of compensating for single-phase grounding fault currents and improving power supply reliability. By overcompensating the capacitive current to the ground, the arc suppression coil can effectively suppress the residual current at the fault point to a safe arc extinguishing range, thereby significantly reducing the risk of arc reignition and achieving high-quality and reliable control of single-phase grounding faults.

[0003] At present, electromechanical hybrid on-load tap-changers have been deeply studied by relevant scholars. Hybrid on-load tap-changers extend the life of mechanical contacts by suppressing arcs during the switching process of the tap-changer. However, in order to solve the hard switching problem, hybrid on-load tap-changers need to add complex buffer circuits; in addition, since mechanical contacts are retained, hybrid on-load tap-changers cannot achieve cross-level regulation, and the response speed of ground fault current regulation is slow, making it difficult to ensure fast and reliable fault regulation in ground fault scenarios. [Summary of the invention]

[0004] In view of this, the present invention provides a ground fault current control system, method, device and storage medium.

[0005] The specific technical scheme of the first embodiment of the present invention is: a ground fault current control system, the system comprising: a converter, an arc suppression coil, a plurality of groups of fast mechanical switches and a bias transformer; one end of the arc suppression coil is connected to a distribution network, the other end of the arc suppression coil is connected to one end of the plurality of groups of fast mechanical switches, the other end of the plurality of groups of mechanical switches is connected to the input end of the bias transformer, the output end of the bias transformer is connected to the distribution network, the input end of the converter is connected to the distribution network, and the output end of the converter is connected to the winding end of the bias transformer; the arc suppression coil is used to compensate for the capacitive current of the distribution network; the plurality of groups of fast mechanical switches are used to output and compensate for the equivalent inductance of the distribution network according to an arc-free tapping method according to different gears and the capacitive current; the arc-free tapping method includes that the branch current of the fast mechanical switch to be switched is zero; the converter is used to transmit the voltage of the distribution network to the bias transformer; the bias transformer is used to output an equivalent series voltage corresponding to the equivalent inductance according to the equivalent inductance and the voltage of the distribution network, and output the equivalent series voltage to the distribution network.

[0006] Preferably, the converter includes a rectifier, an inverter and a capacitor; the input end of the rectifier is connected to the distribution network, the output end of the rectifier is respectively connected in parallel with the filter capacitor and the input end of the inverter, and the output end of the inverter is connected to the winding end of the bias transformer; the rectifier is used to draw power from the distribution network and send a DC voltage to the filter capacitor; the filter capacitor is used to filter the DC voltage; the inverter is used to receive the filtered DC voltage and output an AC voltage to the bias transformer.

[0007] Preferably, the rectifier includes a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode; the inverter includes a first freewheeling diode, a second freewheeling diode, a third freewheeling diode and a fourth freewheeling diode, a first fully-controlled device, a second fully-controlled device, a third fully-controlled device and a fourth fully-controlled device; the positive electrode of the first diode, the positive electrode of the second diode, the positive electrode of the third diode, the negative electrode of the fourth diode, the negative electrode of the fifth diode and the negative electrode of the sixth diode are all connected to the power distribution network, and the negative electrode of the first diode, the negative electrode of the second diode and the negative electrode of the third diode are all connected to one end of the filter capacitor, the collector of the first fully-controlled device, the negative electrode of the first freewheeling diode The anode of the fourth diode, the anode of the fifth diode and the anode of the sixth diode are all connected to the other end of the filter capacitor, the emitter of the third fully-controlled device, the anode of the third freewheeling diode, the emitter of the fourth fully-controlled device and the anode of the fourth freewheeling diode, the emitter of the first fully-controlled device, the collector of the third fully-controlled device, the anode of the first freewheeling diode and the cathode of the third freewheeling diode are connected to the opposite-name ends of the bias transformer winding, and the emitter of the second fully-controlled device, the collector of the fourth fully-controlled device, the anode of the second freewheeling diode and the cathode of the fourth fully-controlled device are connected to the same-name end of the bias transformer winding.

[0008] Preferably, the arc extinguishing coil is divided into 2n gears according to the design rule of an arithmetic progression, namely N, ±1, ... ±n gears, and a fast mechanical switch is set for each gear; each fast mechanical switch includes an even-numbered fast mechanical switch for controlling each gear to input or cut off the lower branch of the bias transformer and an odd-numbered fast mechanical switch for controlling the upper branch of the bias transformer, all the even-numbered fast mechanical switches are connected to the bias transformer through an even-numbered tap collection line, and all the odd-numbered fast mechanical switches are connected to the bias transformer through an odd-numbered tap collection line.

[0009] Preferably, the bias transformer is a three-winding transformer, which includes a primary winding, a first secondary winding and a second secondary winding, two ends of the primary winding are connected to the output end of the converter, the input end of the first secondary winding is connected to the odd-numbered tap collection line of the fast mechanical switch, the input end of the second secondary winding is connected to the even-numbered tap collection line of the fast mechanical switch, and the output end of the first secondary winding and the output end of the second secondary winding are connected to the distribution network.

[0010] Preferably, the system also includes a balancing winding; the input end of the balancing winding is connected to the output end of the bias transformer, and the output end of the balancing winding is connected to the distribution network; the balancing winding is used to balance the equivalent series voltage output by the inverter during the opening or closing process of the fast mechanical switch.

[0011] Preferably, the arc-free tapping method includes: during the operation of the even-numbered fast mechanical switches of the lower branch, after controlling the current of the lower branch to be zero, the inverter injects an equivalent series voltage into the upper branch, and after the current of the lower branch is zero, the even-numbered fast mechanical switches of the lower branch are operated; during the operation of the odd-numbered fast mechanical switches of the upper branch: after controlling the current of the upper branch to be zero, the inverter injects an equivalent series voltage into the lower branch, and after the current of the upper branch is zero, the odd-numbered fast mechanical switches of the upper branch are operated.

[0012] The specific technical solution of the second embodiment of the present invention is: a ground fault current control method, applied to the ground fault current control system as described in the first embodiment of the present application, the method comprising: an arc suppression coil compensates for the capacitive current of the distribution network; multiple groups of fast mechanical switches output and compensate for the equivalent inductance of the distribution network according to the arc-free tapping method according to different gears and the capacitive current; the arc-free tapping method includes the branch current of the fast mechanical switch to be switched being zero; the converter transmits the voltage of the distribution network to the bias transformer; the bias transformer outputs an equivalent series voltage corresponding to the equivalent inductance according to the equivalent inductance and the voltage of the distribution network, and outputs the equivalent series voltage to the distribution network.

[0013] Preferably, the arc-free tapping method includes: during the operation of the even-numbered fast mechanical switches of the lower branch, after controlling the current of the lower branch to be zero, the inverter injects an equivalent series voltage into the upper branch, and after the current of the lower branch is zero, the even-numbered fast mechanical switches of the lower branch are operated; during the operation of the odd-numbered fast mechanical switches of the upper branch: after controlling the current of the upper branch to be zero, the inverter injects an equivalent series voltage into the lower branch, and after the current of the upper branch is zero, the odd-numbered fast mechanical switches of the upper branch are operated.

[0014] The specific technical solution of the third embodiment of the present invention is: a ground fault current control device, including a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method described in any one of the second embodiments of the present application.

[0015] Implementing the embodiments of the present invention will have the following beneficial effects:

[0016] The present invention compensates the capacitive current of the distribution network through an arc suppression coil; multiple groups of fast mechanical switches output the equivalent inductance of the compensation distribution network according to the arc-free tapping method according to different gears and capacitive currents; the converter transmits the voltage of the distribution network to the bias transformer; the bias transformer outputs an equivalent series voltage corresponding to the equivalent inductance according to the equivalent inductance and the voltage of the distribution network, and outputs the equivalent series voltage to the distribution network. The present invention is composed of a converter and a low-cost fast mechanical switch, and suppresses the switch branch current of the fast mechanical switch to be switched to zero through the arc-free tapping method, thereby realizing fast arc-free tapping conversion, and effectively solving the problem of slow regulation response speed.

Brief Description of the Drawings

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a structural schematic diagram of a first embodiment of a ground fault current control system;

[0019] Figure 2 It is a structural schematic diagram of a second embodiment of a ground fault current control system;

[0020] Figure 3 This is the control signal principle diagram of the arc-free turn-adjusting process;

[0021] Figure 4 This is the flow chart of arc-free on-load tapping;

[0022] Figure 5a is a schematic diagram of the current waveform of the upper branch current;

[0023] Figure 5b is a schematic diagram of the current waveform of the lower branch current;

[0024] Figure 5c A schematic diagram of a current waveform of a fault-controlled current;

[0025] Figure 6It is the fault current simulation waveform diagram;

[0026] Figure 7 A flow chart of the steps for ground fault current control;

[0027] Among them, 101 is a converter; 102 is an arc suppression coil; 103 is a fast mechanical switch; 104 is a bias transformer; and 105 is a balancing winding. [Specific implementation method]

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] The terms "first", "second", etc. in the specification, claims and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or modules is not limited to the listed steps or modules, but optionally includes steps or modules that are not listed, or optionally includes other steps or modules that are inherent to these processes, methods, products or devices.

[0030] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] See also Figure 1, is a structural diagram of a ground fault current control system in the first embodiment of the present application, the control system comprises: a converter 101, an arc extinguishing coil 102, a plurality of groups of fast mechanical switches 103 and a bias transformer 104; one end of the arc extinguishing coil 102 is connected to a power distribution network, the other end of the arc extinguishing coil 102 is connected to one end of the plurality of groups of fast mechanical switches 103, the other end of the plurality of groups of mechanical switches 103 is connected to an input end of the bias transformer 104, the output end of the bias transformer 104 is connected to the power distribution network, the input end of the converter 101 is connected to the power distribution network, and the output end of the converter 101 is connected to the power distribution network. The end is connected to the winding end of the bias transformer; the arc suppression coil 102 is used to compensate for the capacitive current of the distribution network; multiple groups of fast mechanical switches 103 are used to output the equivalent inductance of the compensation distribution network according to the arc-free tapping method according to different gears and capacitive currents; the arc-free tapping method includes that the branch current of the fast mechanical switch to be switched is zero; the converter 101 is used to transfer the voltage of the distribution network to the bias transformer 104; the bias transformer 104 is used to output an equivalent series voltage corresponding to the equivalent inductance according to the equivalent inductance and the voltage of the distribution network, and output the equivalent series voltage to the distribution network.

[0032] Specifically, the converter is used to transfer the voltage of the distribution network to the bias transformer; the bias transformer is connected to the AC output port of the inverter, and the equivalent series voltage is injected into the loop through the three-winding structure and the inverter in a reasonable manner, thereby realizing flexible control of the upper branch current or the lower branch current; the arc extinguishing coil is a dry arc extinguishing coil, which is the core equipment for realizing arc extinguishing of ground faults. It is divided into 2n gears according to the design rule of arithmetic progression, and each gear leads to a tap, which is convenient for fast mechanical switches to realize gear adjustment; the fast mechanical switch is used to realize gear adjustment of the dry arc extinguishing coil, and the equivalent inductance value in series with the zero-sequence loop is changed by the opening and closing of the fast mechanical switch, thereby ensuring high-reliability control of ground faults;

[0033] The system in this embodiment is composed of a converter and a low-cost fast mechanical switch. The arc-free tapping method is used to suppress the switch branch current of the fast mechanical switch to be switched to zero, thereby achieving fast arc-free tapping conversion, effectively solving the problem of slow regulation response speed.

[0034] In a specific embodiment, the converter includes a rectifier, an inverter and a capacitor; the input end of the rectifier is connected to the distribution network, the output end of the rectifier is connected in parallel with the input end of the filter capacitor and the inverter respectively, and the output end of the inverter is connected to the winding end of the bias transformer; the rectifier is used to draw power from the distribution network and send a DC voltage to the filter capacitor; the filter capacitor is used to filter the DC voltage; the inverter is used to receive the filtered DC voltage and output an AC voltage to the bias transformer. Specifically, the rectifier is based on the uncontrolled rectification principle to achieve DC voltage stability of the converter, thereby providing a reliable energy supply for the inverter's arc-free turn adjustment; the inverter relies on a stable DC voltage and achieves flexible control and adjustment of the upper branch current or the lower branch current based on the arc-free turn adjustment method, thereby achieving arc-free turn adjustment of the arc suppression coil.

[0035] In the specific embodiments, see Figure 2 , the rectifier includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5 and a sixth diode D6;

[0036] The inverter comprises a first freewheeling diode T1, a second freewheeling diode T2, a third freewheeling diode T3 and a fourth freewheeling diode T4, a first fully-controlled device S1, a second fully-controlled device S2, a third fully-controlled device S2 and a fourth fully-controlled device S4; the anode of the first diode D1, the anode of the second diode D2, the anode of the third diode D3, the cathode of the fourth diode D4, the cathode of the fifth diode D5 and the cathode of the sixth diode D6 are all connected to the power distribution network, the cathode of the first diode D1, the cathode of the second diode D2 and the cathode of the third diode D3 are all connected to one end of the filter capacitor C, the collector of the first fully-controlled device S1, the cathode of the first freewheeling diode T1, the collector of the second fully-controlled device S2 and the cathode of the second The cathode of the freewheeling diode T2, the anode of the fourth diode D4, the anode of the fifth diode D5 and the anode of the sixth diode D6 are all connected to the other end of the filter capacitor C, the emitter of the third fully-controlled device S3, the anode of the third freewheeling diode T3, the emitter of the fourth fully-controlled device S4 and the anode of the fourth freewheeling diode T4, the emitter of the first fully-controlled device S1, the collector of the third fully-controlled device S3, the anode of the first freewheeling diode T1 and the cathode of the third freewheeling diode T3 are connected to the opposite-name ends of the bias transformer winding, and the emitter of the second fully-controlled device S2, the collector of the fourth fully-controlled device S4, the anode of the second freewheeling diode T2 and the cathode of the fourth fully-controlled device S4 are connected to the same-name ends of the bias transformer winding.

[0037] Specifically, the rectifier includes six diodes, which are powered by the power distribution network to provide a stable DC side voltage; the right inverter includes four fully controlled devices S1~S4 and freewheeling diodes connected in parallel therewith, the emitter of S1 and the collector of S3 serve as the input end of the inverter, the emitter of S2 and the collector of S4 serve as the output end of the inverter, the positive electrode of the DC side capacitor is connected to the collector of S1, and the negative electrode is connected to the emitter of S3, the emitter of S2 is connected to the same end of the primary winding of the bias voltage device, and the emitter of S1 is connected to the other end of the primary winding of the bias voltage device.

[0038] In a specific embodiment, the arc extinguishing coil is divided into 2n gears according to the design rule of an arithmetic progression, namely N, ±1, ... ±n gears, and a fast mechanical switch is set for each gear; each fast mechanical switch includes an even-numbered fast mechanical switch for controlling each gear to input or cut off the lower branch of the bias transformer and an odd-numbered fast mechanical switch for controlling the upper branch of the bias transformer, all the even-numbered fast mechanical switches are connected to the bias transformer through an even-numbered tap collection line, and all the odd-numbered fast mechanical switches are connected to the bias transformer through an odd-numbered tap collection line.

[0039] Specifically, the fast mechanical switch includes a fast mechanical switch k for controlling each gear to be put into or cut off. ia and k ib , where k ia is the even-numbered fast mechanical switch of the i-th gear in the lower branch, k ib is the odd-numbered fast mechanical switch of the upper branch in the i-th gear. The dry arc extinguishing coil is divided into 2n (n is an integer) gears according to the arithmetic sequence design rule, namely N, ±1, ... ±n gears, so as to realize different gear switching.

[0040] In a specific embodiment, the bias transformer is a three-winding transformer, and the three-winding transformer includes a primary winding, a first secondary winding, and a second secondary winding. The two ends of the primary winding are connected to the output end of the converter, the input end of the first secondary winding is connected to the odd-numbered tap collection line of the fast mechanical switch, the input end of the second secondary winding is connected to the even-numbered tap collection line of the fast mechanical switch, and the output end of the first secondary winding and the output end of the second secondary winding are connected to the power distribution network. Specifically, the bias transformer is a three-winding transformer, specifically including a primary winding and two secondary windings, and the two ends of the primary winding are connected to the converter; one secondary winding is connected to the odd-numbered tap collection line, which is the same-name end; the other secondary winding is connected to the even-numbered tap collection line, which is the opposite-name end.

[0041] In a specific embodiment, the system further includes a balancing winding 105; the input end of the balancing winding is connected to the output end of the bias transformer, and the output end of the balancing winding is connected to the power distribution network; the balancing winding is used to balance the equivalent series voltage output by the inverter during the opening or closing process of the fast mechanical switch. Specifically, the balancing winding is used to balance the equivalent series voltage of the inverter during the opening or closing process of the fast mechanical switch, thereby ensuring stable operation of the inverter.

[0042] In a specific embodiment, the arc-free tapping method includes: during the operation of the even-numbered fast mechanical switch of the lower branch, after controlling the current of the lower branch to be zero, the inverter injects an equivalent series voltage into the upper branch, and after the current of the lower branch is zero, the even-numbered fast mechanical switch of the lower branch is operated; during the operation of the odd-numbered fast mechanical switch of the upper branch: after controlling the current of the upper branch to be zero, the inverter injects an equivalent series voltage into the lower branch, and after the current of the upper branch is zero, the odd-numbered fast mechanical switch of the upper branch is operated.

[0043] Specifically, take the adjustment of the dry arc suppression coil from N gear to +1 gear as an example:

[0044] (1) At position N, both odd and even switches are closed, the control loop current is zero, and the upper branch current and lower branch current Not affected by branch voltage potential difference, fault-controlled current is evenly distributed;

[0045] (2) Control the lower branch current is zero, at which point the upper branch current bears all the fault control current, and then the odd-numbered switches are closed at the +1 position, and the even-numbered switches are still closed at the N position;

[0046] (3) The control loop current is zero, the upper branch current and lower branch current Not affected by branch voltage potential difference, fault-controlled current is evenly distributed;

[0047] (4) Control the upper branch current is zero, at which point the upper branch current bears all the fault control current, and then the even-numbered switches are closed at +1, and the odd-numbered taps are closed at +1;

[0048] (5) Both odd and even switches are closed in the +1 position, the control circulation current is zero, and the upper branch current and lower branch current Not affected by branch voltage potential difference, fault-controlled current is evenly distributed.

[0049] Specifically, Figure 2 middle is the grid side phase voltage; is the neutral point voltage of the power grid; C 0x(x=a,b,c) is the line capacitance; G f is the fault transition conductance. Please refer to the schematic diagram of the control signal of the arc-free turn regulation process Figure 3 , take the adjustment from N gear to +1 gear as an example. When the control signal M=0, the current of the lower branch is controlled Guaranteed upper branch current Takes on all fault regulation current; controls the upper branch current when the control signal M=1 Guaranteed lower branch current Takes on all fault regulation currents; when the control signal M=2, guarantees the upper branch current and lower branch current It is not affected by the branch voltage potential difference and the fault current is evenly distributed. Assume that a single-phase grounding fault occurs in the distribution network, that is, during t0-t5; during t0-t1, it is in monitoring mode, and the control signal M=2. At this time, k Na ,k Nb are all closed, and turn adjustment is started when it is detected that turn adjustment is needed; during t1~t2, it is arc-free turn adjustment mode, control signal M=0, k Na Disconnect, k 1a Closed; during t2~t3, it is arc-free turn-adjusting mode, control signal M=2, at this time k Nb ,k 1a Closed; during t3~t4, it is arc-free turn-adjusting mode, control signal M=1, k Nb Disconnect, k 1b Closed; during t4~t5, it is monitoring mode, control signal M=2, at this time k 1a ,k 1b All are closed, the turn adjustment process is completed, and the turn adjustment is continued to be monitored. Figure 4 , which is a flow chart of arc-free on-load tapping in the present invention. By real-time single-phase grounding fault detection on the distribution network, when a single-phase grounding fault occurs, the required inductance is calculated, the control switch is disconnected, and then the gear is adjusted to the target gear. During the turn adjustment process, the arc-free tapping procedure is performed step by step. After the turn adjustment is completed, the control switch is closed to achieve arc-free turn adjustment. Figure 5a is the upper branch current Current waveform, Figure 5b is the lower branch current Current waveform, Figure 5c Regulating current for faults Current waveform: Taking the adjustment from N gear to +1 gear as an example, the simulation is set as follows: the arc-free turn adjustment mode is entered at 0.01s; the lower branch current during 0.01s to 0.02s are suppressed to zero; k are disconnected in sequence during 0.02s to 0.04s Na , closed k 1a; During the period of 0.04s to 0.05s, the upper branch and the lower branch are not affected by the branch voltage potential difference, and the fault control current is evenly distributed. During the period of 0.05s to 0.06s, the upper branch current are suppressed to zero; k are disconnected in sequence during 0.06s to 0.08s Nb , closed k 1b ; Analysis of the simulation waveform shows that the present invention effectively suppresses the arc during the fast mechanical switch action process, and realizes the fast arc-free turn adjustment of the arc extinguishing coil, and the time required for a single turn adjustment is only 70ms. The fault control current is basically unchanged in the detection mode and the arc-free turn adjustment mode, ensuring that the arc-free turn adjustment has basically no effect on the fault control current. Figure 6 , which is a fault current simulation waveform diagram of the present invention. By analyzing the simulation waveform, it can be seen that the present invention can quickly achieve effective control of single-phase grounding faults under the premise of rapid arc-free turn regulation.

[0050] In the specific embodiments, see Figure 7 , is a flow chart of steps of a ground fault current control method in the second embodiment of the present application, which is applied to the ground fault current control system as described in the first embodiment of the present application, and the method includes:

[0051] Step 201, the arc suppression coil compensates for the capacitive current of the distribution network;

[0052] Step 202, multiple groups of fast mechanical switches output to compensate for the equivalent inductance of the distribution network according to the arc-free tapping method according to different gears and the capacitive current; the arc-free tapping method includes that the branch current of the fast mechanical switch to be switched is zero;

[0053] Step 203: The converter transmits the voltage of the power distribution network to the bias transformer;

[0054] Step 204: The bias transformer outputs an equivalent series voltage corresponding to the equivalent inductance according to the equivalent inductance and the voltage of the distribution network, and outputs the equivalent series voltage to the distribution network.

[0055] The method in this embodiment suppresses the switch branch current of the fast mechanical switch to be switched to zero through the arc-free tapping method, thereby realizing fast arc-free tapping conversion, and effectively solving the problem of slow regulation response speed.

[0056] In a specific embodiment, the arc-free tapping method includes: during the operation of the even-numbered fast mechanical switch of the lower branch, after controlling the current of the lower branch to be zero, the inverter injects an equivalent series voltage into the upper branch, and after the current of the lower branch is zero, the even-numbered fast mechanical switch of the lower branch is operated; during the operation of the odd-numbered fast mechanical switch of the upper branch: after controlling the current of the upper branch to be zero, the inverter injects an equivalent series voltage into the lower branch, and after the current of the upper branch is zero, the odd-numbered fast mechanical switch of the upper branch is operated.

[0057] In a specific embodiment, the third embodiment of the present application provides a ground fault current control device, including a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of any one of the methods described in the second embodiment of the present application.

[0058] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0059] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A ground fault current control system, characterized in that: The system comprises: a converter, an arc suppression coil, a plurality of groups of fast mechanical switches and a bias transformer; one end of the arc suppression coil is connected to a power distribution network, the other end of the arc suppression coil is connected to one end of the plurality of groups of fast mechanical switches, the other end of the plurality of groups of mechanical switches is connected to an input end of the bias transformer, an output end of the bias transformer is connected to the power distribution network, an input end of the converter is connected to the power distribution network, and an output end of the converter is connected to a winding end of the bias transformer; The arc suppression coil is used to compensate for the capacitive current of the power distribution network; The multiple groups of fast mechanical switches are used to output and compensate the equivalent inductance of the distribution network according to the arc-free tapping method according to different gears and the capacitive current; the arc-free tapping method includes that the branch current of the fast mechanical switch to be switched is zero; The converter is used to transfer the voltage of the power distribution network to the bias transformer; The bias transformer is used to output an equivalent series voltage corresponding to the equivalent inductance according to the equivalent inductance and the voltage of the distribution network, and output the equivalent series voltage to the distribution network.

2. The ground fault current control system according to claim 1, characterized in that: The converter includes a rectifier, an inverter and a capacitor; the input end of the rectifier is connected to the power distribution network, the output end of the rectifier is connected in parallel with the filter capacitor and the input end of the inverter respectively, and the output end of the inverter is connected to the winding end of the bias transformer; The rectifier is used to draw power from the distribution network and send a DC voltage to the filter capacitor; The filter capacitor is used to filter the DC voltage; The inverter is used to receive the filtered DC voltage and output an AC voltage to the bias transformer.

3. The ground fault current control system according to claim 2, characterized in that: The rectifier includes a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode; The inverter comprises a first freewheeling diode, a second freewheeling diode, a third freewheeling diode and a fourth freewheeling diode, a first fully-controlled device, a second fully-controlled device, a third fully-controlled device and a fourth fully-controlled device; The anode of the first diode, the anode of the second diode, the anode of the third diode, the cathode of the fourth diode, the cathode of the fifth diode and the cathode of the sixth diode are all connected to the power distribution network, the cathode of the first diode, the cathode of the second diode and the cathode of the third diode are all connected to one end of the filter capacitor, the collector of the first fully-controlled device, the cathode of the first freewheeling diode, the collector of the second fully-controlled device and the cathode of the second freewheeling diode, the anode ... the power distribution network, the cathode of the first diode, the cathode of the second diode and the cathode of the third diode are all connected to the power distribution network, the cathode of the first diode, the cathode of the second diode and the cathode of the third diode are all connected to the power distribution network, the cathode of the first diode, the cathode of the second diode and the cathode of the third diode are all connected to the power distribution network, the cathode of the first diode, the cathode of the second diode and the cathode of the third diode are all connected to the power distribution network, the cathode of the first diode, the cathode of the second diode and the cathode of the third diode are all connected to the power distribution network, the cathode of the first diode The other end of the filter capacitor, the emitter of the third fully-controlled device, the anode of the third freewheeling diode, the emitter of the fourth fully-controlled device and the anode of the fourth freewheeling diode are connected, the emitter of the first fully-controlled device, the collector of the third fully-controlled device, the anode of the first freewheeling diode and the cathode of the third freewheeling diode are connected to the opposite-name end of the bias transformer winding, and the emitter of the second fully-controlled device, the collector of the fourth fully-controlled device, the anode of the second freewheeling diode and the cathode of the fourth fully-controlled device are connected to the same-name end of the bias transformer winding.

4. The ground fault current control system according to claim 1, characterized in that: The arc extinguishing coil is divided into 2n gears according to the design rule of arithmetic progression, namely N, ±1, ... ±n gears, and a fast mechanical switch is set for each gear; Each fast mechanical switch includes an even-numbered fast mechanical switch for controlling each gear to input or cut off the lower branch of the bias transformer and an odd-numbered fast mechanical switch for controlling the upper branch of the bias transformer. All the even-numbered fast mechanical switches are connected to the bias transformer through an even-numbered tap collection line, and all the odd-numbered fast mechanical switches are connected to the bias transformer through an odd-numbered tap collection line.

5. The ground fault current control system according to claim 4, characterized in that: The bias transformer is a three-winding transformer, which includes a primary winding, a first secondary winding and a second secondary winding. Both ends of the primary winding are connected to the output end of the converter, the input end of the first secondary winding is connected to the odd-numbered tap collection line of the fast mechanical switch, the input end of the second secondary winding is connected to the even-numbered tap collection line of the fast mechanical switch, and the output end of the first secondary winding and the output end of the second secondary winding are connected to the distribution network.

6. The ground fault current control system according to claim 1, characterized in that: The system further comprises a balancing winding; the input end of the balancing winding is connected to the output end of the bias transformer, and the output end of the balancing winding is connected to the power distribution network; The balancing winding is used to balance the equivalent series voltage output by the inverter during the opening or closing process of the fast mechanical switch.

7. The ground fault current control system according to claim 1, characterized in that: The arc-free tapping method comprises: During the operation of the even-numbered fast mechanical switches of the lower branch, after controlling the current of the lower branch to be zero, the inverter injects an equivalent series voltage into the upper branch, and after the current of the lower branch is zero, the even-numbered fast mechanical switches of the lower branch are operated; During the operation of the odd-numbered fast mechanical switches of the upper branch: after controlling the current of the upper branch to be zero, the inverter injects an equivalent series voltage into the lower branch, and after the current of the upper branch is zero, the odd-numbered fast mechanical switches of the upper branch are operated.

8. A ground fault current control method, applied to the ground fault current control system as claimed in claim 1, characterized in that: The method comprises: The arc suppression coil compensates for the capacitive current of the power distribution network; Multiple groups of fast mechanical switches output the equivalent inductance of the distribution network according to the arc-free tapping method according to different gears and the capacitive current; the arc-free tapping method includes that the branch current of the fast mechanical switch to be switched is zero; The converter transmits the voltage of the power distribution network to the bias transformer; The bias transformer outputs an equivalent series voltage corresponding to the equivalent inductance according to the equivalent inductance and the voltage of the distribution network, and outputs the equivalent series voltage to the distribution network.

9. The ground fault current control method according to claim 8, characterized in that: The arc-free tapping method comprises: During the operation of the even-numbered fast mechanical switches of the lower branch, after controlling the current of the lower branch to be zero, the inverter injects an equivalent series voltage into the upper branch, and after the current of the lower branch is zero, the even-numbered fast mechanical switches of the lower branch are operated; During the operation of the odd-numbered fast mechanical switches of the upper branch: after controlling the current of the upper branch to be zero, the inverter injects an equivalent series voltage into the lower branch, and after the current of the upper branch is zero, the odd-numbered fast mechanical switches of the upper branch are operated.

10. A ground fault current control device, comprising a memory and a processor, characterized in that: The memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method according to any one of claims 8 to 9.

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