Low-voltage area fault simulation test platform and test method of switchable grounding system

Abstract

The application discloses a low-voltage transformer area fault simulation test platform and test method of a switchable grounding system, belongs to the field of power distribution testing, and comprises a low-voltage transformer area simulation unit for simulating a power distribution environment of a low-voltage transformer area; the low-voltage transformer area simulation unit comprises three-phase power supply lines, a neutral line, a grounding line and a device to be tested, three phases of the device to be tested are connected with the three-phase power supply lines, and the three-phase power supply lines are provided with fault access points; a fault simulation unit is connected with the fault access points of the low-voltage transformer area simulation unit and used for simulating short-circuit faults and over / under voltage faults; and a grounding system switching unit is connected with the fault access points, the neutral line and the grounding line and used for switching different grounding systems. The application can solve the problem that the prior art cannot simulate low-voltage transformer area faults under different grounding systems.

Description

Technical Field

[0001] This invention belongs to the field of power distribution testing, specifically relating to a low-voltage distribution area fault simulation test platform and test method for switchable grounding systems. Background Technology

[0002] As the "last mile" of power supply services, low-voltage distribution networks directly serve end users and are characterized by rapidly changing management needs, large-scale management equipment, and high service requirements. With the large-scale integration of distributed renewable energy, the increasing complexity of user load characteristics, and the growing demand for power supply reliability, low-voltage distribution networks face multiple technical challenges.

[0003] Currently, traditional simulation platforms are unable to reproduce fault conditions under different complex grounding systems, thus failing to effectively support personnel in dealing with complex fault scenarios. This results in insufficient preparation for personnel in actual operations, thereby limiting the efficiency and accuracy of fault handling. Summary of the Invention

[0004] The purpose of this invention is to provide a low-voltage distribution area fault simulation test platform and test method with switchable grounding system, so as to solve the problem that the existing technology cannot simulate low-voltage distribution area faults under different grounding systems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] Firstly, a low-voltage distribution area fault simulation test platform with a switchable grounding system includes:

[0007] Low-voltage distribution area simulation unit, used to simulate the power distribution environment of low-voltage distribution areas;

[0008] The low-voltage distribution area simulation unit includes a three-phase power line, a neutral line, a grounding line, and a device under test. The three phases of the device under test are connected to the three-phase power line respectively. The three-phase power line has a fault access point. Each phase of the three-phase power line is connected to a resistor to simulate the actual cable resistance.

[0009] The fault simulation unit is connected to the fault access point of the low-voltage distribution area simulation unit and is used to simulate short-circuit faults and over / under voltage faults.

[0010] The grounding system switching unit connects the fault access point, the neutral line, and the grounding line, and is used to switch between different grounding systems.

[0011] In some embodiments, the grounding system switching unit includes: a device metal part grounding point switching module, a system neutral point switching module, and an operating mode switching module;

[0012] The equipment metal part grounding point switching module connects the metal part of the equipment under test, the equipment grounding point, the neutral line, and the grounding line.

[0013] The system's neutral point switching module connects the power grounding point, three-phase power lines, and neutral line through an isolation transformer. This effectively prevents the neutral line from being directly grounded due to faults (such as short circuits or lightning strikes), which can lead to ground potential imbalance, reduce the risk of electric shock, and prevent third harmonics from affecting the upstream power system through isolation.

[0014] The operating mode switching module connects to the system neutral point switching module, neutral line, and grounding line.

[0015] In some embodiments, the device metal part grounding point switching module includes a three-position switch S5 and a first grounding resistor, the resistance of which is less than or equal to 4 ohms. The three-position switch S5 has a contact point 1, a contact point 2, a contact point 3, and a contact. During operation, the contact is connected to the contact point 1, the contact point 2, and the contact point 3 at different positions. The fixed end of the three-position switch S5 is connected to the metal part of the device under test, the contact point 1 is connected to the neutral line, the contact point 2 is connected to the grounding line, and the contact point 3 is connected to the device grounding point through the first grounding resistor.

[0016] The neutral point switching module of the system includes: switch S3, switch S4, and 1000. A resistor, switch S3, and switch S4 are connected in parallel and connected to the neutral point of the three-phase power supply line and the neutral line through an isolation transformer. Switch S3 is connected to a 1000Ω transformer. The resistor is connected to the power supply ground point, and the switch S4 is also connected to the power supply ground point.

[0017] The operation mode switching module includes switches S1 and S2. One end of switch S1 is connected to switches S3 and S4 in parallel, and the other end is connected to the grounding wire. One end of switch S2 is connected to the neutral wire, and the other end is connected to the grounding wire.

[0018] In some embodiments, the fault simulation unit includes a short-circuit fault generation device and an over / under voltage simulation device.

[0019] The short-circuit fault generating device includes a two-position switch S6, a two-position switch S7, a two-position switch S8, and a 0.31... Resistance, 0.33 Resistors and thyristors;

[0020] Double-position switches S6, S7, and S8 all have contact point 1 and contact point 2.

[0021] The fixed terminals of dual-position switches S6, S7, and S8 are respectively connected to the cathode of the thyristor, and the anode of the thyristor is connected to the fault access point.

[0022] The first contact point of double-position switches S6, S7, and S8 is connected to a 0.33... The resistors are interconnected, and the second contact of double-position switches S6, S7, and S8 are connected via 0.31... The resistor is grounded.

[0023] In some embodiments, the over / under voltage simulation device includes: inductor L, inductor L1, capacitor C, switch S9, and switch S10;

[0024] Inductor L is connected in parallel with switches S9 and S10 and connected to the fault access point. Switch S9 is connected in series with capacitor C and grounded, and switch S10 is connected in series with inductor L1 and grounded.

[0025] Secondly, a low-voltage distribution area fault simulation test method for a switchable grounding system, based on the aforementioned low-voltage distribution area fault simulation test platform, includes the following steps:

[0026] The power distribution environment of a low-voltage distribution area is simulated using a low-voltage distribution area simulation unit.

[0027] Different grounding systems can be switched through a grounding system switching unit. The grounding systems include: TT system (Terra-Terra System, a system that separates protective grounding and neutral grounding), TN-S system (Terra-Neutral Separated System, a system that separates protective grounding and neutral), TN-C system (Terra-Neutral Combined System, a system that combines protective grounding and neutral), TN-CS system (Terra-Neutral Combined and Separated System, a system that partially combines and partially separates protective grounding and neutral), and IT system (Isolated Terra System).

[0028] The fault simulation unit is connected to the fault access point to simulate short-circuit faults or over / under voltage faults. During the simulation, the test data and waveforms of the device under test are recorded.

[0029] In some implementations, the step of switching between different grounding systems via a grounding system switching unit specifically includes:

[0030] After remotely controlling switch S1 to the open position, switch S2 to the open position, switch S3 to the open position, switch S4 to the closed position, and three-position switch S5 to contact point 3, switch to the TT system.

[0031] Remotely control switch S1 to the closed position, switch S2 to the open position, switch S3 to the open position, switch S4 to the closed position, and then remotely control the three-position switch S5 to contact point 2 to switch to the TN-S system.

[0032] After remotely controlling switch S1 to the open position, switch S2 to the open position, switch S3 to the open position, switch S4 to the closed position, and three-position switch S5 to contact point 1, switch to the TN-C system.

[0033] Remotely control switch S1 to the open position, switch S2 to the closed position, switch S3 to the open position, switch S4 to the closed position, and then remotely control the three-position switch S5 to contact point 2 to switch to the TN-CS system.

[0034] Remotely control switch S1 to the open position, switch S2 to the open position, switch S3 to the closed position, switch S4 to the open position, and three-position switch S5 to contact point 2 to switch to the IT system.

[0035] In some implementations, the fault access points include: point a, point a1, point b, point b1, point c, and point c1; the three-phase power lines include: phase A, phase B, and phase C; points a and a1 are located on phase A, points b and b1 are located on phase B, and points c and c1 are located on phase C.

[0036] The steps of connecting the fault simulation unit to the fault access point to simulate short-circuit faults or over / under-voltage faults specifically include:

[0037] The anodes of each thyristor in the short-circuit fault generating device are connected to points a, b, and c of the fault access point, respectively. After remotely controlling the dual-position switches S6, S7, and S8 to contact point 1, a three-phase short-circuit fault is simulated.

[0038] Remotely control any two of the two-position switches S6, S7 and S8 to contact point 1, and then remotely control the remaining two-position switch to the open position to simulate a two-phase short circuit fault.

[0039] Remotely control any one of the two-position switches S6, S7, and S8 to contact point 2, and then remotely control the remaining two two-position switches to the open position to simulate a single-phase ground fault.

[0040] In some implementations, when simulating three-phase short-circuit faults and two-phase short-circuit faults, the two-position switches S6, S7 and S8 are not interlocked.

[0041] When simulating a single-phase ground fault, the two-position switches S6, S7 and S8 are interlocked.

[0042] When simulating three-phase short-circuit faults, two-phase short-circuit faults, and single-phase ground faults, the duration of occurrence of the corresponding fault is controlled by controlling the conduction time of the thyristors.

[0043] In some implementations, the step of connecting the fault simulation unit to the fault access point to simulate a short-circuit fault or an over / under voltage fault further includes:

[0044] Connect over- and under-voltage simulation devices between points a and a1, points b and b1, and points c and c1 respectively at the fault access points. Remotely control the switches S9 and S10 of each over- and under-voltage simulation device to the closed position to simulate three-phase over- and under-voltage.

[0045] Connect an over / under voltage simulation device between points a and a1, or between points b and b1, or between points c and c1 at the fault access point, and remotely control switches S9 and S10 to the closed position to simulate single-phase over / under voltage.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] This invention uses a low-voltage distribution area simulation unit to simulate the power distribution environment, a fault simulation unit to simulate short-circuit faults and over / under-voltage faults, and a grounding system switching unit to switch between different grounding systems. This allows for comprehensive verification of the device under test (DUT) under different fault conditions in different grounding systems without requiring separate modifications to the DUT. It enables comparative testing of different faults under the same test environment, solving the problem that existing technologies cannot simulate low-voltage distribution area faults under different grounding systems.

[0048] Furthermore, the grounding system switching unit can support switching of five typical grounding systems—TT system, TN-S system, TN-C system, TN-CS system, and IT system—through the equipment metal part grounding point switching module, system neutral point switching module, and operating mode switching module, thus avoiding the need for repeated physical environment construction.

[0049] Furthermore, the fault simulation unit, through the short-circuit fault generation device, can support three-phase short circuit, two-phase short circuit, and single-phase ground fault simulation, and can verify the withstand capability of the device under test under extreme faults; the over- and under-voltage simulation device, through the combination of inductors and capacitors, simulates voltage fluctuations, and can test the stability of the device under voltage imbalance scenarios.

[0050] Furthermore, during the simulation of a single-phase grounding fault, the interlocking between the two-position switches S6, S7, and S8 can prevent multi-phase grounding from causing an increase in short-circuit current, thus ensuring the safety of equipment and personnel. Attached Figure Description

[0051] Figure 1This is a schematic diagram of the structure of the low-voltage transformer area fault simulation test platform with switchable grounding system provided in Example 1;

[0052] Figure 2 This is a structural diagram of the short-circuit fault generating device provided in Embodiment 1;

[0053] Figure 3 This is a structural diagram of the over / under voltage simulation device provided in Example 1;

[0054] In the diagram, A is phase A, B is phase B, C is phase C, N is neutral, PE is grounding, and PEN is the combined line of N and PE in the TN-C system. Detailed Implementation

[0055] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings. The content described herein is for explanation rather than limitation of the present invention.

[0056] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification and claims of this invention are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, systems, products, or devices.

[0057] Example 1

[0058] like Figure 1 As shown, this embodiment provides a low-voltage distribution area simulation test platform with switchable grounding system, including: a low-voltage distribution area simulation unit, a grounding system switching unit, and a fault simulation unit;

[0059] The low-voltage distribution area simulation unit includes three-phase power lines (corresponding to...) Figure 1The system consists of three phases: A, B, and C; neutral conductor N; protective earth conductor PE; and the device under test (DUT). The three phases of the DUT are connected to the three-phase power lines, which have fault access points. The three-phase power lines, neutral conductor N, and protective earth conductor PE are primarily the power supply section for the low-voltage distribution area simulation unit. Each phase of the three-phase power lines is connected to resistors R1, R2, and R3 to simulate actual cable resistance. The low-voltage distribution area simulation unit uses a busbar, low-voltage intelligent switch, and residual current device (RCD) as core components to simulate the operating environment of the low-voltage distribution area. It connects to the distribution area fusion terminal via RS485 (Recommended Standard 485), remote signaling, and low-power wireless communication methods to monitor low-voltage side environmental quantities, electrical quantities, switch status, load data, and reactive power compensation monitoring data. Therefore, the low-voltage intelligent switch and RCD are used as the DUT for joint testing and verification.

[0060] The fault simulation unit is connected to the fault access point (corresponding to) of the low-voltage distribution area simulation unit. Figure 1 Points a, a1, b, b1, c, and c1 in the diagram are used to simulate short-circuit faults and over / under voltage faults.

[0061] The grounding system switching unit connects the fault access point, the neutral line N, and the grounding line PE, and is used to switch between different grounding systems.

[0062] like Figure 1 As shown, the grounding system switching unit includes a device metal part grounding point switching module, a system neutral point switching module, and an operating mode switching module;

[0063] The equipment's metal part grounding point switching module includes a three-position switch S5 and a first grounding resistor ( Figure 1 The middle is 4 The resistor (S5) controls the grounding method of the device under test (DUT). The first grounding resistor has a resistance value of less than or equal to 4 ohms. The three-position switch S5 has contact points 1, 2, and 3, and contacts. During operation, the contacts are connected to contact points 1, 2, and 3 at different positions. The fixed end of the three-position switch S5 is connected to the metal part of the DUT. Contact point 1 is connected to the neutral line N, contact point 2 is connected to the grounding line PE, and contact point 3 is connected to the grounding line PE. Resistor connection to the equipment grounding point;

[0064] The neutral point switching module of the system includes: switch S3, switch S4, and 1000. The resistor can control the low-voltage distribution area fault simulation test platform to be grounded via a large resistor or directly. Switch S3 is connected in parallel with switch S4 and connected to the neutral point of the three-phase power supply line and neutral line N through an isolation transformer. Switch S3 is connected to a 1000Ω resistor. The resistor is connected to the power supply ground point, and the switch S4 is also connected to the power supply ground point.

[0065] The operation mode switching module includes switches S1 and S2, which can control the low-voltage distribution area fault simulation test platform to operate in three-phase four-wire or three-phase five-wire mode. One end of switch S1 is connected to switches S3 and S4 in parallel, and the other end is connected to the grounding wire PE. One end of switch S2 is connected to the neutral wire N, and the other end is connected to the grounding wire PE.

[0066] The fault simulation unit includes a short-circuit fault generation device and an over / under voltage simulation device, such as... Figure 2 As shown, the short-circuit fault generating device includes a two-position switch S6, a two-position switch S7, a two-position switch S8, and a 0.31... Resistance, 0.33 The resistor and thyristor are used. Two-position switches S6, S7, and S8 each have contact point 1 and contact point 2. The fixed terminals of switches S6, S7, and S8 are connected to the cathodes of the thyristors, and the anodes of the thyristors are connected to points a, b, and c, respectively. Contact point 1 of switches S6, S7, and S8 is connected via a 0.33... The resistors are interconnected, and the second contact of double-position switches S6, S7, and S8 are connected via 0.31... Resistor grounding;

[0067] Specifically, contact point 1 of the two-position switch S6 passes through 0.33 The resistor is connected to the phase B resistor (i.e., the 0.33 resistor connected to contact point 1 of the two-position switch S7). Resistor), C-phase resistor (i.e., the 0.33 resistor connected to contact point 1 of the two-position switch S8). (Resistor) Short-circuited; Contact 1 of the two-position switch S7 is connected through 0.33 The resistor is connected to the phase A resistor (i.e., the 0.33 resistor connected to contact point 1 of the two-position switch S6). The resistor in phase C is short-circuited; contact point 1 of the two-position switch S8 is connected through 0.33 The resistor is short-circuited with both phase A and phase B resistors.

[0068] The short-circuit fault generator can connect to points a, b, and c of the fault access point to simulate three-phase short-circuit faults, two-phase short-circuit faults, and single-phase ground faults. When simulating phase-to-phase short-circuit faults (i.e., three-phase and two-phase short-circuit faults), the two-position switches S6, S7, and S8 are not interlocked and no interlocking device is required. However, when simulating a single-phase ground fault, the two-position switches S6, S7, and S8 are interlocked and an interlocking device is required. The short-circuit fault generator can control the fault duration by controlling the conduction time of the thyristors.

[0069] like Figure 3 As shown, the over / under voltage simulation device includes inductor L, inductor L1, capacitor C, switch S9, and switch S10. Inductor L is connected in parallel with switches S9 and S10 and connected to the fault access point. Switch S9 is connected in series with capacitor C and grounded. Switch S10 is connected in series with inductor L1 and grounded. The over / under voltage simulation device is connected between points a and a1, or between points b and b1, or between points c and c1.

[0070] Switches S1, S2, S3, S4, three-position switch S5, two-position switch S6, two-position switch S7, two-position switch S8, switch S9, and switch S10 are all remote control switches.

[0071] Example 2

[0072] Based on the low-voltage distribution area fault simulation test platform provided in Embodiment 1, this embodiment provides a low-voltage distribution area fault simulation test method with a switchable grounding system, including the following steps:

[0073] Step 1: Simulate the power distribution environment of the low-voltage distribution area using the low-voltage distribution area simulation unit;

[0074] Step 2: Switch between different grounding systems through the grounding system switching unit. The grounding systems include: TT system, TN-S system, TN-C system, TN-CS system, and IT system.

[0075] Specifically, when using the TT system, switch S1 is remotely controlled to the open position, switch S2 is remotely controlled to the open position, switch S3 is remotely controlled to the open position, switch S4 is remotely controlled to the closed position, and the three-position switch S5 is remotely controlled to contact point 3, then switch to the TT system.

[0076] Remotely control switch S1 to the closed position, switch S2 to the open position, switch S3 to the open position, switch S4 to the closed position, and then remotely control the three-position switch S5 to contact point 2 to switch to the TN-S system.

[0077] After remotely controlling switch S1 to the open position, switch S2 to the open position, switch S3 to the open position, switch S4 to the closed position, and three-position switch S5 to contact point 1, switch to the TN-C system.

[0078] Remotely control switch S1 to the open position, switch S2 to the closed position, switch S3 to the open position, switch S4 to the closed position, and then remotely control the three-position switch S5 to contact point 2 to switch to the TN-CS system.

[0079] Remotely control switch S1 to the open position, switch S2 to the open position, switch S3 to the closed position, switch S4 to the open position, and three-position switch S5 to contact point 2 to switch to the IT system.

[0080] Step 3: After switching to the corresponding grounding system, connect the anodes of the three thyristors of the short-circuit fault generating device to points a, b, and c of the fault access point respectively. After remotely controlling the dual-position switches S6, S7, and S8 to contact point 1, simulate a three-phase short-circuit fault.

[0081] Remotely control any two of the two-position switches S6, S7 and S8 to contact point 1, and then remotely control the remaining two-position switch to the open position to simulate a two-phase short circuit fault.

[0082] Remotely control any one of the two-position switches S6, S7 and S8 to contact point 2, and then remotely control the remaining two two-position switches to the open position to simulate a single-phase ground fault.

[0083] When simulating three-phase short-circuit faults and two-phase short-circuit faults, the two-position switches S6, S7 and S8 are not interlocked.

[0084] When simulating a single-phase ground fault, the two-position switches S6, S7 and S8 are interlocked.

[0085] When simulating three-phase short-circuit faults, two-phase short-circuit faults, and single-phase ground faults, the duration of occurrence of the corresponding fault is controlled by controlling the conduction time of the thyristors.

[0086] Step 4: Record the test data and waveforms of the device under test during the simulation process, and perform test analysis.

[0087] Example 3

[0088] Unlike Embodiment 2, this embodiment connects an over / under voltage simulation device at the fault connection point. Therefore, steps 1 and 2 are the same as in Embodiment 2. After the grounding system switching is completed, the steps of the low-voltage distribution area fault simulation test method with switchable grounding system provided in this embodiment that differ from those in Embodiment 3 include:

[0089] Step 3: When simulating three-phase over- and under-voltage, connect over- and under-voltage simulation devices between points a and a1, points b and b1, and points c and c1 respectively at the fault connection point, and remotely control the switches S9 and S10 of each over- and under-voltage simulation device to the closed position.

[0090] When simulating single-phase over / under voltage, connect an over / under voltage simulation device between points a and a1, or between points b and b1, or between points c and c1 at the fault connection point, and remotely control switches S9 and S10 to the closed position.

[0091] Step 4: Record the test data and waveforms of the device under test during the simulation process, and perform test analysis.

[0092] Based on the above embodiments, this invention connects to the neutral line N of the low-voltage distribution area simulation unit via switch S2; connects to the grounding line PE via switch S1; and grounds the power supply point via switch S3 or switch S4; using a three-position switch S5 to select the grounding method for the casing of the device under test. The A, B, and C phases of the device under test are connected to the A, B, and C phases of the power supply section of the low-voltage distribution area simulation unit. When switching between different grounding systems, the switching states of switches S1, S2, S3, S4, and S5 can be controlled to switch between different grounding systems. Combined with the fault simulation unit, it can simulate fault handling of the same fault type under different grounding systems, achieving low-voltage distribution area operation status monitoring, realistic fault simulation, and device under test status detection. This comprehensively verifies new equipment affected by abnormal operating conditions of the low-voltage distribution area under different grounding systems, providing technical support and decision-making basis for the construction and maintenance of low-voltage distribution areas.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A low-voltage distribution area fault simulation test platform with a switchable grounding system, characterized in that, include: Low-voltage distribution area simulation unit, used to simulate the power distribution environment of low-voltage distribution areas; The low-voltage distribution area simulation unit includes a three-phase power line, a neutral line, a grounding line, and a device under test. The three phases of the device under test are connected to the three-phase power line respectively. The three-phase power line has a fault access point. Each phase of the three-phase power line is connected to a resistor to simulate the actual cable resistance. The fault simulation unit is connected to the fault access point of the low-voltage distribution area simulation unit and is used to simulate short-circuit faults and over / under voltage faults. A grounding system switching unit is connected to the fault access point, the neutral line and the grounding line, and is used to switch between different grounding systems; The grounding system switching unit includes: a device metal part grounding point switching module, a system neutral point switching module, and an operating mode switching module; The equipment metal part grounding point switching module connects the metal part of the equipment under test, the equipment grounding point, the neutral line, and the grounding line. The system neutral point switching module connects the power grounding point, the three-phase power lines, and the neutral line through an isolation transformer. The operating mode switching module connects to the system neutral point switching module, neutral line, and grounding line; The device metal part grounding point switching module includes a three-position switch S5 and a first grounding resistor. The resistance of the first grounding resistor is less than or equal to 4 ohms. The three-position switch S5 has a contact point 1, a contact point 2, a contact point 3, and a contact. During operation, the contact is connected to the contact point 1, the contact point 2, and the contact point 3 at different positions. The fixed end of the three-position switch S5 is connected to the metal part of the device under test. The contact point 1 is connected to the neutral line, the contact point 2 is connected to the grounding line, and the contact point 3 is connected to the device grounding point through the first grounding resistor. The neutral point switching module of the system includes: switch S3, switch S4, and 1000. A resistor, switch S3, and switch S4 are connected in parallel and connected to the neutral point of the three-phase power supply line and the neutral line through an isolation transformer. Switch S3 is connected to a 1000Ω transformer. The resistor is connected to the power supply ground point, and the switch S4 is also connected to the power supply ground point. The operation mode switching module includes switch S1 and switch S2. One end of switch S1 is connected to switches S3 and S4 in parallel, and the other end is connected to the grounding wire. One end of switch S2 is connected to the neutral wire, and the other end is connected to the grounding wire. When in use, different grounding systems are switched through the grounding system switching unit. Switch S1 is remotely controlled to the open position, switch S2 is remotely controlled to the open position, switch S3 is remotely controlled to the open position, switch S4 is remotely controlled to the closed position, and the three-position switch S5 is remotely controlled to contact point 3 to switch to the TT system. Remotely control switch S1 to the closed position, switch S2 to the open position, switch S3 to the open position, switch S4 to the closed position, and then remotely control the three-position switch S5 to contact point 2 to switch to the TN-S system. After remotely controlling switch S1 to the open position, switch S2 to the open position, switch S3 to the open position, switch S4 to the closed position, and three-position switch S5 to contact point 1, switch to the TN-C system. Remotely control switch S1 to the open position, switch S2 to the closed position, switch S3 to the open position, switch S4 to the closed position, and then remotely control the three-position switch S5 to contact point 2 to switch to the TN-CS system. Remotely control switch S1 to the open position, switch S2 to the open position, switch S3 to the closed position, switch S4 to the open position, and three-position switch S5 to contact point 2 to switch to the IT system.

2. The low-voltage distribution area fault simulation test platform with a switchable grounding system according to claim 1, characterized in that, The fault simulation unit includes a short-circuit fault generation device and an over / under voltage simulation device. The short-circuit fault generating device includes a two-position switch S6, a two-position switch S7, a two-position switch S8, and a 0.31... Resistance, 0.33 Resistors and thyristors; Double-position switches S6, S7, and S8 all have contact point 1 and contact point 2. The fixed terminals of dual-position switches S6, S7, and S8 are respectively connected to the cathode of the thyristor, and the anode of the thyristor is connected to the fault access point. The first contact point of double-position switches S6, S7, and S8 is connected to a 0.33... The resistors are interconnected, and the second contact of double-position switches S6, S7, and S8 are connected via 0.31... The resistor is grounded.

3. The low-voltage distribution area fault simulation test platform with a switchable grounding system according to claim 2, characterized in that, The over / under voltage simulation device includes: inductor L, inductor L1, capacitor C, switch S9, and switch S10; Inductor L is connected in parallel with switches S9 and S10 and connected to the fault access point. Switch S9 is connected in series with capacitor C and grounded, and switch S10 is connected in series with inductor L1 and grounded.

4. A method for simulating faults in low-voltage distribution areas using a switchable grounding system, characterized in that, The low-voltage distribution area fault simulation test platform according to claim 3 includes the following steps: The power distribution environment of a low-voltage distribution area is simulated using a low-voltage distribution area simulation unit. Different grounding systems can be switched through a grounding system switching unit. The grounding systems include: TT system, TN-S system, TN-C system, TN-CS system, and IT system. The fault simulation unit is connected to the fault access point to simulate short-circuit faults or over / under voltage faults. During the simulation, the test data and waveforms of the device under test are recorded.

5. The method for simulating faults in a low-voltage distribution area of ​​a switchable grounding system according to claim 4, characterized in that, The fault access points include: point a, point a1, point b, point b1, point c, and point c1. The three-phase power lines include: phase A, phase B, and phase C. Points a and a1 are located on phase A, points b and b1 are located on phase B, and points c and c1 are located on phase C. The steps of connecting the fault simulation unit to the fault access point to simulate short-circuit faults or over / under-voltage faults specifically include: The anodes of each thyristor in the short-circuit fault generating device are connected to points a, b, and c of the fault access point, respectively. After remotely controlling the dual-position switches S6, S7, and S8 to contact point 1, a three-phase short-circuit fault is simulated. Remotely control any two of the two-position switches S6, S7 and S8 to contact point 1, and then remotely control the remaining two-position switch to the open position to simulate a two-phase short circuit fault. Remotely control any one of the two-position switches S6, S7, and S8 to contact point 2, and then remotely control the remaining two two-position switches to the open position to simulate a single-phase ground fault.

6. The method for simulating faults in a low-voltage distribution area of ​​a switchable grounding system according to claim 5, characterized in that, When simulating three-phase short-circuit faults and two-phase short-circuit faults, the two-position switches S6, S7 and S8 are not interlocked. When simulating a single-phase ground fault, the two-position switches S6, S7 and S8 are interlocked. When simulating three-phase short-circuit faults, two-phase short-circuit faults, and single-phase ground faults, the duration of occurrence of the corresponding fault is controlled by controlling the conduction time of the thyristors.

7. The method for simulating faults in a low-voltage distribution area of ​​a switchable grounding system according to claim 5, characterized in that, The steps of connecting the fault simulation unit to the fault access point to simulate short-circuit faults or over / under-voltage faults also specifically include: Connect over- and under-voltage simulation devices between points a and a1, points b and b1, and points c and c1 respectively at the fault access points. Remotely control the switches S9 and S10 of each over- and under-voltage simulation device to the closed position to simulate three-phase over- and under-voltage. Connect an over / under voltage simulation device between points a and a1, or between points b and b1, or between points c and c1 at the fault access point, and remotely control switches S9 and S10 to the closed position to simulate single-phase over / under voltage.

Images