A realistic test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in power distribution networks.

Abstract

This invention discloses a realistic test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network. The system includes: a feeder, a phase-controlled switch, a circuit breaker, a first isolating switch, a second isolating switch, a third isolating switch, a fourth isolating switch, a first grounding switch, a second grounding switch, parallel lead wires, multiple vacuum contactors, and a mobile resistor box. Through the connection of the isolating switches, phase-controlled switches, grounding switches, cable junction boxes, mobile resistor boxes, and current-limiting reactors, safe, efficient simulation and flexible switching between single-phase grounding and phase-to-phase short-circuit faults in the distribution network are achieved. Switching between single-phase grounding and phase-to-phase short-circuit faults in the distribution network can be completed within a limited space, significantly reducing the time and space required for conducting different test scenarios. Only one phase-controlled switch is needed to meet the angle control requirements for both single-phase grounding fault and phase-to-phase short-circuit tests, significantly reducing the cost of the test equipment.

Description

Technical Field

[0001] This invention relates to the field of power distribution network technology, and more specifically, to a real-world test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in power distribution networks. Background Technology

[0002] Single-phase grounding and phase-to-phase faults are common line faults in distribution network operation. When a single-phase grounding fault occurs, it is usually necessary to quickly locate the fault point using line selection, section selection, and phase selection equipment. When a phase-to-phase short-circuit fault occurs, the switch needs to accurately detect the large current and trip. To effectively verify the correctness of the fault handling of these intelligent switching devices, it is necessary to simulate real fault conditions on the line. However, due to the high voltage on the 10kV side, it is also necessary to simulate various grounding scenarios such as sand, cement, soil, grassland, and ponds, as well as large current short-circuit tests of thousands of amperes. In actual simulation tests, there are problems such as large workload for simulating faults, difficulty in implementation, and potential safety hazards. Currently, most of the fault simulations carried out by the State Grid Corporation are conducted on the actual distribution network frame. During the test, a power outage plan needs to be arranged, and alternative solutions for the corresponding fault types need to be found on site. The State Grid Hubei Electric Power Research Institute uses water resistance to simulate grounding faults in different scenarios and has achieved good results. However, there are a series of problems such as large workload on site, inconvenient device installation, inability to control the angle of fault occurrence, and the need for power outage. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a real-world test system for power distribution networks that allows for flexible switching between single-phase grounding and phase-to-phase short-circuit faults. It features the ability to flexibly switch between various single-phase grounding fault scenarios and various short-circuit fault scenarios, and to freely adjust the fault grounding resistance.

[0004] According to one aspect of the present invention, a full-scale test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network is provided, comprising:

[0005] Feeder line, phase control switch 3, circuit breaker 4, first isolating switch 5, second isolating switch 6, third isolating switch 7, fourth isolating switch 8, first grounding switch 9, second grounding switch 10, parallel lead wire 11, multiple vacuum contactors 12, and mobile resistor box 13; among which

[0006] Any two phases on the feeder can be T-connected;

[0007] One end of the first isolating switch 5 is connected to one phase of the feeder, and the other end is connected to the circuit breaker 4.

[0008] One end of the second isolating switch 6 is connected to the other phase of the feeder, and the other end is connected to the phase control switch 3;

[0009] The third isolating switch 7 is connected to the phase control switch 3 and the parallel lead wire 11;

[0010] The fourth isolating switch 8 is connected to the third isolating switch 7 and the phase control switch 3;

[0011] The first grounding switch 9 is installed between the circuit breaker 4 and the first isolating switch 5;

[0012] The second grounding switch 10 is installed between the phase control switch 3 and the second isolating switch 6;

[0013] Multiple vacuum contactors 12 are connected to parallel lead wires 11;

[0014] The movable resistor box 13 is pluggably connected to multiple vacuum contactors 12.

[0015] Optionally, the full-scale test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in the distribution network also includes a current-limiting reactor 15, which is installed between the circuit breaker 4 and the fourth isolating switch 8.

[0016] Optionally, the full-scale test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in the distribution network also includes a cable junction box, which is used to house the cables of each vacuum contactor 12.

[0017] Optionally, the movable resistor box 13 includes: multiple resistors 131, multiple detachable connecting leads 132, a supporting steel plate 133, and multiple lead connectors 134; wherein

[0018] The connection between multiple resistors 131 can be changed via detachable connecting leads 132;

[0019] Support plate 133 is used to place resistor 131;

[0020] Connect lead connector 134 and resistor 131.

[0021] Optionally, the detachable connecting lead 132 adopts an insert structure to allow for detachment or connection with the lead connector 134.

[0022] Alternatively, resistor 131 is a non-inductive nickel-chromium alloy resistor.

[0023] Optionally, resistor 131 has a resistance of 1000 ohms and a rated capacity of 10kW.

[0024] According to another aspect of the present invention, a real-world test method for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network is provided, comprising:

[0025] The test of fault handling capability after a single-phase wire breakage in the feeder falls into the target scenario involves installing the test specimen at a preset position on the single-phase feeder.

[0026] Open the phase control switch, close the isolating switch on the disconnected phase, close the vacuum contactor of the ground fault branch in the target scenario, open the vacuum contactor of other fault branches besides the target scenario, and open the isolating switch on the phase that is not disconnected.

[0027] Move the mobile resistor box to the fault area, connect the upper resistor of the mobile resistor box, and adjust the resistance of the mobile resistor box to the target resistance.

[0028] Connect the tail end of the isolating switch on the single-phase branch line of the ground fault to the head end of the mobile resistor box with a ground wire. After connecting the tail end of the mobile resistor box with a ground wire, place the ground wire into the target scene of the fault area.

[0029] Power is supplied to the entire distribution network grounding fault simulation system, the fault occurrence angle is selected, the phase control switch is closed, and it is determined whether the test object operates correctly.

[0030] After the single-phase grounding test is completed, the entire distribution network grounding fault simulation system is de-energized. Then, the target isolating switch closest to the parallel lead wire is opened, and all other isolating switches except the target isolating switch are closed.

[0031] Power is supplied to the entire distribution network grounding fault simulation system, the fault occurrence angle is selected, the phase control switch is closed, and it is determined whether the test object operates correctly.

[0032] This invention achieves safe, efficient simulation and flexible switching of single-phase grounding and phase-to-phase short-circuit faults in distribution networks through the connection of isolating switches, phase-controlled switches, grounding switches, cable junction boxes, mobile resistor boxes, and current-limiting reactors. It allows for switching between single-phase grounding and phase-to-phase short-circuit faults in distribution networks within a limited space, significantly reducing the time and space required for different test scenarios. Only one phase-controlled switch is needed to meet the angle control requirements for both single-phase grounding fault and phase-to-phase short-circuit tests, greatly reducing the cost of the test equipment. It also features the ability to freely adjust the fault grounding resistance and short-circuit current. This design uses only a small amount of equipment to reproduce various faults that may occur in actual distribution networks, maximizing the safety of test personnel. It has advantages such as simple structure and convenient operation, and can be applied to different test scenarios. Attached Figure Description

[0033] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0034] Figure 1 This is a framework diagram of a real-world test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network, provided by an exemplary embodiment of the present invention.

[0035] Figure 2 This is a top view of a movable resistor box provided in an exemplary embodiment of the present invention;

[0036] Figure 3 This is a flowchart illustrating a real-world test method for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network, provided by an exemplary embodiment of the present invention. Detailed Implementation

[0037] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0038] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0039] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0040] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0041] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more unless explicitly defined or given contrary instructions in the context.

[0042] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0043] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0044] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0045] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0046] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0047] Exemplary System

[0048] Figure 1 This is a framework diagram of a real-world test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network, provided by an exemplary embodiment of the present invention. Figure 1 As shown, the full-scale test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network includes: a feeder, a phase-controlled switch 3, a circuit breaker 4, a first isolating switch 5, a second isolating switch 6, a third isolating switch 7, a fourth isolating switch 8, a first grounding switch 9, a second grounding switch 10, parallel lead wires 11, multiple vacuum contactors 12, and a mobile resistor box 13; wherein any two phases on the feeder are T-connected; one end of the first isolating switch 5 is connected to one phase of the feeder, and the other end is connected to the circuit breaker 4; the second isolating switch 9... One end of switch 6 is connected to the other phase of the feeder, and the other end is connected to phase control switch 3; the third isolating switch 7 is connected to phase control switch 3 and parallel lead wire 11; the fourth isolating switch 8 is connected to the third isolating switch 7 and phase control switch 3; the first grounding switch 9 is installed between circuit breaker 4 and the first isolating switch 5; the second grounding switch 10 is installed between phase control switch 3 and the second isolating switch 6; multiple vacuum contactors 12 are connected to parallel lead wire 11; the mobile resistor box 13 is plugged into multiple vacuum contactors 12.

[0049] Specifically, any two phases on the feeder are T-connected, such as Figure 1 As shown, phase A 1 of the 10kV feeder is T-connected to phase B 2 of the 10kV feeder. Phase-controlled switch 3 is the main switch of the test system with phase angle control function. Circuit breaker 4 is the circuit breaker for short-circuit testing. First isolating switch 5 is the isolating switch on the circuit breaker for short-circuit testing. Second isolating switch 6 is the isolating switch on the phase-controlled switch. Third isolating switch 7 is the isolating switch under the phase-controlled switch. Fourth isolating switch 8 is the isolating switch under the circuit breaker system. First grounding switch 9 is the grounding switch for short-circuit testing. Second grounding switch 10 is the main grounding switch of the system. Parallel lead wire 11 is the parallel lead wire for the 10kV fault device. Vacuum contactor 12 is the vacuum contactor for triggering ground faults. There is only one movable resistor box 13, which can be moved to the corresponding position according to the test needs. The ground fault simulation area 14 can be expanded, for example, the line can fall onto a tree or other foreign object. Current-limiting reactor 15 is a current-limiting reactor with adjustable reactance. The test sample 16 can also be referred to as the test device.

[0050] Furthermore, isolating switches are installed on both the upper and lower sides of the phase-controlled switch and the circuit breaker used for short-circuit testing, providing dual protection. When performing fault wiring, the isolating switches on either the upper or lower side of the phase-controlled switch must be disconnected. Grounding switches are installed in front of the phase-controlled switch and behind the isolating switch closest to the feeder. The portable resistor box simulates grounding resistance values ​​under various grounding scenarios such as sand, cement, soil, grass, and ponds. Multiple resistors are connected in series and parallel to achieve adjustable resistance steps from 0 ohms to 9000 ohms.

[0051] Therefore, this invention uses a phase-controlled switch with angle control capability as the trigger switch of the test system. Combined with the wiring method of the test system, it can realize the trigger angle control of single-phase grounding fault and short-circuit fault using only one phase-controlled switch, which significantly reduces the test cost. At the same time, the compact design can greatly reduce the footprint of the test grid.

[0052] Optionally, the full-scale test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in the distribution network also includes a current-limiting reactor 15, which is installed between the circuit breaker 4 and the fourth isolating switch 8.

[0053] Specifically, the current-limiting reactor simulates faults with different short-circuit currents by adjusting the reactance value according to the system impedance. It can achieve an adjustable short-circuit current of 1000A-8000A to meet the short-circuit test requirements of different scenarios.

[0054] Optionally, the full-scale test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in the distribution network also includes a cable junction box, which is used to house the cables of each vacuum contactor 12.

[0055] Specifically, the cable junction box is used to bring down the 10kV feeder to ensure the safety of the test personnel and the long-term outdoor placement of the test equipment.

[0056] Optionally, such as Figure 2 As shown, the movable resistor box 13 includes: multiple resistors 131, multiple detachable connecting leads 132, a supporting steel plate 133, and multiple lead connectors 134; wherein the multiple resistors 131 are connected in different ways through the detachable connecting leads 132; the supporting steel plate 133 is used to place the resistors 131; and the lead connectors 134 are connected to the resistors 131.

[0057] Optionally, the detachable connecting lead 132 adopts an insert structure to allow for detachment or connection with the lead connector 134.

[0058] Alternatively, resistor 131 is a non-inductive nickel-chromium alloy resistor.

[0059] Optionally, resistor 131 has a resistance of 1000 ohms and a rated capacity of 10kW.

[0060] Specifically, the short-circuit current can be freely adjusted using the movable resistor box 13. Since the capacity of a single resistor is limited and coil-type resistors have reactance, this patent uses multiple non-inductive nickel-chromium alloy resistors connected in series and parallel to increase the grounding resistance capacity, preventing the grounding resistor from burning out. This also avoids situations where the resistance inductance is too large and inconsistent with the actual characteristics of the power grid fault. Jumpers can be used to connect the resistors, increasing the safety and practicality of the device.

[0061] Therefore, the real-world test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in distribution networks proposed in this embodiment achieves safe, efficient simulation and flexible switching between single-phase grounding and phase-to-phase short-circuit faults in distribution networks through the connection of isolating switches, phase-controlled switches, grounding switches, cable junction boxes, mobile resistor boxes, and current-limiting reactors. Using the wiring method of the test system studied in this invention, the real-world test network for single-phase grounding faults and phase-to-phase short-circuit faults can be quickly switched simply by switching phase-controlled switches without changing the network structure. Switching between single-phase grounding and phase-to-phase short-circuit faults in distribution networks can be completed within a limited space, significantly reducing the time and space required for conducting different test scenarios. Only one phase-controlled switch is needed to meet the angle control requirements for single-phase grounding fault tests and phase-to-phase short-circuit tests, significantly reducing the cost of test equipment. It has the function of freely adjusting the fault grounding resistance value and the short-circuit current magnitude. This design can reproduce various faults that may occur in actual distribution networks with only a small number of devices, maximizing the protection of the personal safety of test personnel. It has the advantages of simple structure and convenient operation, and can be applied to different test scenarios.

[0062] Exemplary methods

[0063] Figure 3 This is a flowchart illustrating a real-world test method for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network, provided by an exemplary embodiment of the present invention. Figure 3 As shown, the method includes:

[0064] The test of fault handling capability after a single-phase wire breakage in the feeder falls into the target scenario involves installing the test specimen at a preset position on the single-phase feeder.

[0065] Open the phase control switch, close the isolating switch on the disconnected phase, close the vacuum contactor of the ground fault branch in the target scenario, open the vacuum contactor of other fault branches besides the target scenario, and open the isolating switch on the phase that is not disconnected.

[0066] Move the mobile resistor box to the fault area, connect the upper resistor of the mobile resistor box, and adjust the resistance of the mobile resistor box to the target resistance.

[0067] Connect the tail end of the isolating switch on the single-phase branch line of the ground fault to the head end of the mobile resistor box with a ground wire. After connecting the tail end of the mobile resistor box with a ground wire, place the ground wire into the target scene of the fault area.

[0068] Power is supplied to the entire distribution network grounding fault simulation system, the fault occurrence angle is selected, the phase control switch is closed, and it is determined whether the test object operates correctly.

[0069] After the single-phase grounding test is completed, the entire distribution network grounding fault simulation system is de-energized. Then, the target isolating switch closest to the parallel lead wire is opened, and all other isolating switches except the target isolating switch are closed.

[0070] Power is supplied to the entire distribution network grounding fault simulation system, the fault occurrence angle is selected, the phase control switch is closed, and it is determined whether the test object operates correctly.

[0071] The following example illustrates the specific application of this method: "A 10kV line phase A breaks and falls into a pond".

[0072] First, a fault handling capability test was conducted to simulate the situation where a 10kV line A phase breaks and falls into a pond. The test sample was installed at point 16 on the line.

[0073] Then Figure 1 The phase control switch 3 is opened, the isolating switch 6 on the main switch and the isolating switch 7 under the main switch are closed, the vacuum contactor of the pond grounding fault branch is closed, and the vacuum contactors of other fault branches, as well as the short-circuit test circuit breaker 4, the isolating switch 5 on the short-circuit test circuit breaker and the isolating switch 8 of the short-circuit fault system are opened.

[0074] Move the mobile resistor box 13 to the pond fault area, connect the upper resistor of the mobile resistor box 13, and use a 3 parallel and 3 series connection to make the overall resistance of the resistor box 1000 ohms.

[0075] Connect the ground wire at the tail end of the isolating switch under the A phase branch line of the pond grounding fault to the head end of the mobile resistor box 13. After connecting the ground wire at the tail end of the mobile resistor box 13, place the ground wire into the water pool in the pond fault area.

[0076] Power is supplied to the entire 10kV distribution network grounding fault simulation system. When the fault occurs at an angle, such as a voltage angle of 30°, phase control switch 3 is closed to reproduce the fault of phase A falling into the pond after the wire breaks. The test object 16 is then judged to determine whether it operates correctly.

[0077] After the single-phase grounding test is completed, the system is de-energized. Then, the circuit breaker 4 for the short-circuit test, the isolating switch 5 on the circuit breaker for the short-circuit test, the isolating switch 6 on the main switch, and the isolating switch 8 of the short-circuit fault system are closed, and the isolating switch 7 under the main switch is opened.

[0078] Adjust the reactance value of current-limiting reactor 15 to the system short-circuit current of 5000A.

[0079] Power is supplied to the entire 10kV distribution network grounding fault simulation system. The fault occurrence angle is selected. For example, when the voltage angle is 90°, the phase control switch 3 is closed to reproduce the fault after the AB phase short circuit. It is then determined whether the test object 16 operates correctly.

[0080] Therefore, by connecting isolating switches, phase-controlled switches, grounding switches, cable junction boxes, mobile resistor boxes, and current-limiting reactors, safe, efficient simulation and flexible switching of single-phase grounding and phase-to-phase short-circuit faults in distribution networks can be achieved. Switching between single-phase grounding and phase-to-phase short-circuit faults in distribution networks can be completed within a limited space, significantly reducing the time and space required for conducting different test scenarios. Only one phase-controlled switch is needed to meet the angle control requirements for single-phase grounding fault tests and phase-to-phase short-circuit tests, greatly reducing the cost of test equipment. It has the function of freely adjusting the fault grounding resistance value and the short-circuit current magnitude. This design can reproduce various faults that may occur in actual distribution networks with only a small number of devices, maximizing the protection of the personal safety of test personnel. It has the advantages of simple structure and convenient operation, and can be applied to different test scenarios.

[0081] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0082] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0083] The block diagrams of devices, systems, devices, and systems involved in this invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, systems, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0084] The methods and systems of the present invention may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of the present invention are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, the present invention may also be implemented as a program recorded on a recording medium, the program comprising machine-readable instructions for implementing the methods according to the present invention. Thus, the present invention also covers recording media storing programs for performing the methods according to the present invention.

[0085] It should also be noted that in the systems, apparatus, and methods of the present invention, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalents of the present invention. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0086] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A full-scale test system for flexible switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network, characterized in that, include: Feeder line, phase control switch (3), circuit breaker (4), first isolating switch (5), second isolating switch (6), third isolating switch (7), fourth isolating switch (8), first grounding switch (9), second grounding switch (10), parallel lead wire (11), multiple vacuum contactors (12), and mobile resistor box (13); among which Any two phases on the feeder can be T-connected; One end of the first isolating switch (5) is connected to one phase of the feeder, and the other end is connected to the circuit breaker (4); One end of the second isolating switch (6) is connected to the other phase of the feeder, and the other end is connected to the phase control switch (3); The third isolating switch (7) is connected to the phase control switch (3) and the parallel lead wire (11); The fourth isolating switch (8) is connected to the third isolating switch (7) and the phase control switch (3); The first grounding switch (9) is installed between the circuit breaker (4) and the first isolating switch (5); The second grounding switch (10) is installed between the phase control switch (3) and the second isolating switch (6); Multiple vacuum contactors (12) are connected to parallel lead wires (11); The movable resistor box (13) is pluggably connected to multiple vacuum contactors (12); It also includes a current-limiting reactor (15), which is installed between the circuit breaker (4) and the fourth isolating switch (8).

2. The system according to claim 1, characterized in that, It also includes a cable junction box, which is used to house the cables of each vacuum contactor (12).

3. The system according to claim 1, characterized in that, The movable resistor box (13) includes: multiple resistors (131), multiple detachable connecting leads (132), a supporting steel plate (133), and multiple lead connectors (134); wherein The connection between multiple resistors (131) can be changed via detachable connecting leads (132); The supporting steel plate (133) is used to place the resistor (131); The lead connector (134) and the resistor (131) are connected.

4. The system according to claim 3, characterized in that, The detachable connecting lead (132) adopts an insert structure to achieve detachment or connection with the lead connector (134).

5. The system according to claim 3, characterized in that, The resistor (131) is a non-inductive nickel-chromium alloy resistor.

6. The system according to claim 3, characterized in that, The resistance of resistor (131) is 1000 ohms and the rated capacity is 10kW.

7. A method for flexibly switching between single-phase grounding and phase-to-phase short-circuit faults in a distribution network using the full-scale test system as described in claim 1, characterized in that, include: The test of fault handling capability after a single-phase wire breakage in the feeder falls into the target scenario involves installing the test specimen at a preset position on the single-phase feeder. Open the phase control switch, close the isolating switch on the disconnected phase, close the vacuum contactor of the ground fault branch in the target scenario, open the vacuum contactor of other fault branches besides the target scenario, and open the isolating switch on the phase that is not disconnected. Move the mobile resistor box to the fault area, connect the upper resistor of the mobile resistor box, and adjust the resistance of the mobile resistor box to the target resistance. Connect the tail end of the isolating switch on the single-phase branch line of the ground fault to the head end of the mobile resistor box with a ground wire. After connecting the tail end of the mobile resistor box with a ground wire, place the ground wire into the target scene of the fault area. Power is supplied to the entire distribution network grounding fault simulation system, the fault occurrence angle is selected, the phase control switch is closed, and it is determined whether the test object operates correctly. After the single-phase grounding test is completed, the entire distribution network grounding fault simulation system is de-energized. Then, the target isolating switch closest to the parallel lead wire is opened, and all other isolating switches except the target isolating switch are closed. Power is supplied to the entire distribution network grounding fault simulation system, the fault occurrence angle is selected, the phase control switch is closed, and it is determined whether the test object operates correctly.

Images