Test device and test method for distributed energy consumption device of flexible DC transmission system

Abstract

The present invention discloses a test device and test method for a distributed energy consumption device of a flexible direct current transmission system, wherein the test device comprises an alternating current power supply, a transformer, a rectifier circuit, a charging switch, a current limiting resistor, a load inductor, a first test valve section, a second test valve section, an energy replenishment module, an energy replenishment diode, an energy replenishment switch, a distributed energy consumption valve section and a current limiting inductor; the test method is divided into four stages: an uncontrolled charging stage, a cyclic charging stage, an unlocked operation boosting and current boosting stage, and a steady-state equalizing stage; the distributed energy consumption valve section is energized synchronously with the test valve section, and a steady-state equalizing test of the distributed energy consumption valve section is carried out in the unlocked operation state of the two test valve sections. The present invention solves the problem of steady-state equalizing test of distributed energy consumption devices, and the test method is economical, convenient and easy to implement.

Description

Technical Field

[0001] The invention belongs to the technical field of flexible direct current power transmission, and in particular relates to a test device and a test method for a distributed energy consumption device of a flexible direct current power transmission system. Background Art

[0002] my country has a vast territory and abundant wind resources. Transmitting wind power can greatly alleviate the energy shortage in my country. For offshore wind power transmission, flexible direct current transmission has become the optimal solution for wind power transmission. New energy wind power generation is connected to the grid through a flexible direct current transmission system. When an AC fault occurs in the receiving power grid, the DC voltage will rise due to the voltage rise of the converter valve energy accumulation module. The wind turbine has an inertia link with a slow action time. In order to cooperate with the wind turbine action, it is necessary to configure an energy consumption device to limit the DC voltage rise and protect the safety of the converter valve. Distributed energy consumption devices have the advantages of lower current change rate, lower voltage change rate, no need for consistent triggering of energy consumption modules, simple power supply of energy extraction power supply, and high inheritance of development and design, making them the preferred choice for energy consumption.

[0003] Distributed energy consumption devices need to be fully tested and verified during the design process. However, due to the late start of research on distributed energy consumption devices, there is a lack of corresponding test methods and test equipment. If the distributed energy consumption device is matched with the converter valve in the test, a large capacity needs to be configured for the test system when verifying extreme energy consumption. However, it is difficult for many plant areas to meet such requirements. In addition, the test system is complex, difficult to operate, and has high risks. Therefore, there is an urgent need for an economical, convenient, and easy-to-implement method to solve the problem of distributed energy consumption device testing, meet the functional test of distributed energy consumption devices, and test the steady-state voltage balancing ability and DC voltage suppression ability of distributed energy consumption devices. Summary of the invention

[0004] The present invention provides a test device and a test method for a distributed energy dissipation device of a flexible direct current power transmission system, so as to fully test and verify the distributed energy dissipation device during the design process.

[0005] To achieve the above-mentioned object, the present invention provides a test device for a distributed energy consumption device of a flexible direct current transmission system, comprising a first test valve section, a second test valve section, an energy replenishment module, a load inductor L1, a current limiting inductor L2, an AC power supply, a transformer T, a rectifier circuit, a charging circuit switch S1 and an energy replenishment module switch S2; the first test valve section and the second test valve section both comprise a plurality of cascaded power modules;

[0006] The AC power supply is converted into a DC voltage through the transformer T and the rectifier circuit. The first test valve section forms a first branch. The second test valve section is connected in series with the energy compensation module to form a second branch. The distributed energy consumption valve section to be tested is connected in series with the current limiting inductor L2 to form a third branch. The first branch is connected in parallel with the third branch and then connected in parallel with the second branch through the load inductor L1 to form a parallel branch. The parallel branch is then connected in parallel on the DC side of the rectifier circuit through the charging switch S1. The energy compensation module is connected in parallel to the DC side of the rectifier circuit through the energy compensation diode D2 and the energy compensation switch S2.

[0007] Furthermore, the power module includes a capacitor C and two IGBTs, a diode D is connected in anti-parallel at both ends of the two IGBTs, and the capacitor C is connected in parallel at both ends of a branch formed by connecting the two IGBTs.

[0008] Furthermore, the energy compensation module includes a capacitor C9, an IGBT T91 and an IGBT T92. A diode D91 and a diode D92 are respectively connected in anti-parallel at both ends of the IGBT T91 and the IGBT T92. The capacitor C9 is connected in parallel at both ends of a branch formed by connecting the IGBT T91 and the IGBT T92.

[0009] Furthermore, the capacitor C9 of the energy compensation module is connected in parallel to the DC side of the rectifier circuit via the energy compensation diode D2 and the energy compensation switch S2.

[0010] Furthermore, the transformer T is a step-up split transformer.

[0011] Furthermore, a current limiting resistor R1 is connected between the parallel branch and the charging switch S1.

[0012] A test method for a test device of a distributed energy consumption device of a flexible direct current transmission system based on the above-mentioned method comprises the following steps:

[0013] Step 1, uncontrolled charging stage: disconnect the energy replenishment module switch S2, close the charging switch S1, raise the AC power supply voltage, perform uncontrolled charging, and raise the module voltage of the two test valve sections until the energy source can be stably charged. At this time, the first test valve section and the second test valve section are connected in series with the energy replenishment module and the distributed energy consumption valve section in parallel, and the modules of the three valve sections each evenly distribute the voltage output by the rectifier circuit;

[0014] Step 2, cycle charging stage: reduce the voltage of the AC power supply so that the output voltage of the rectifier circuit is the same as the voltage of the first test valve section module, and the first test valve section and the second test valve section are switched to a one-to-one cycle charging mode. At this time, the port voltages of the two test valve sections are lower than the sum of the voltages of the distributed energy consumption valve section modules. The flow diode D1 in the distributed energy consumption module is cut off due to the reverse pressure. The two test valve sections do not charge the distributed energy consumption valve section modules. The distributed energy consumption modules are in a self-discharge state, and the voltage of the distributed energy consumption modules remains basically unchanged for a short time.

[0015] Step 3, unlocking and running the boosting and current raising stage: disconnect the charging circuit switch S1, close the energy replenishment module switch S2, unlock the two test valve sections for operation, synchronously control the AC power supply voltage and the phase angle slope between the two test valve sections to increase the module voltage of the first test valve section and the second test valve section, the voltage of the distributed energy consumption module and the current of the load inductor L1 to the set value;

[0016] Step 4, steady-state voltage equalization stage: when the voltage of the distributed energy consumption module of the distributed energy consumption valve section is higher than the upper limit of the set value, the high-voltage energy consumption module discharges through the energy consumption resistor R1, and stops discharging when the voltage of the energy consumption module is discharged to the lower limit of the set value; the cycle is repeated to simulate the steady-state voltage equalization test of the distributed energy consumption valve section; the voltage setting value of the energy consumption module is gradually reduced to test the ability of the distributed energy consumption device to suppress the DC voltage.

[0017] Furthermore, in step 4, the voltage setting value of the energy consumption module is gradually reduced at a rate of 0.1 kV per second.

[0018] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0019] The test of the distributed energy consumption device of the flexible DC transmission system is to make the voltage of the distributed energy consumption valve section reach the rated voltage through the first test valve section and the second test valve section, and then test the steady-state voltage equalization capacity of the distributed energy consumption device by switching on or off the energy discharge branch in the distributed energy consumption module; and test the ability of the distributed energy consumption device to suppress the DC voltage by adjusting the voltage setting value of the energy consumption module. The circuit of the test device is simple, easy to implement and convenient to operate.

[0020] Furthermore, the capacitor C9 of the energy replenishment module 9 is connected in parallel to the DC side of the rectifier circuit via the energy replenishment diode D2 and the energy replenishment switch S2 to ensure that the power flows to the system.

[0021] Furthermore, the transformer is a step-up split transformer. The primary side of the transformer can use low-voltage conventional electricity (380V) while the secondary side of the transformer must use higher voltage electricity to meet the voltage requirements of the test platform. The split transformer can raise the voltage by voltage superposition;

[0022] Furthermore, a current limiting resistor R1 is connected between the parallel branch and the charging switch S1. The current limiting resistor R1 limits the current of the charging circuit so that the current is not too large during the charging process, thereby protecting the test equipment.

[0023] A test method for distributed energy consumption devices in a flexible direct current transmission system is disclosed. The distributed energy consumption valve section is energized synchronously with the test valve section. A steady-state equalization test of the distributed energy consumption valve section is carried out when the two test valve sections are unlocked and in operation. The ability test of the distributed energy consumption valve section to suppress direct current voltage is carried out during the steady-state equalization stage. The problem of steady-state equalization test and DC voltage suppression test of distributed energy consumption devices is solved. The test method is economical, convenient and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the test topology diagram of distributed energy consumption device in flexible DC transmission system;

[0025] Figure 2 The voltages at the two test valve section ports of the distributed energy consumption device of the flexible DC power transmission system provided in the embodiment of the present invention;

[0026] Figure 3 Voltage of two test valve section modules of the distributed energy consumption device of the flexible DC power transmission system provided in the embodiment of the present invention;

[0027] Figure 4 The voltage of the distributed energy consumption valve section of the distributed energy consumption device of the flexible direct current transmission system provided by the embodiment of the present invention;

[0028] Figure 5 The load inductance current of the distributed energy consumption device of the flexible direct current transmission system provided by the embodiment of the present invention;

[0029] Figure 6 The distributed energy consumption valve section current of the distributed energy consumption device of the flexible direct current transmission system provided by the embodiment of the present invention;

[0030] Figure 7 The power supply power of the distributed energy consumption device of the flexible direct current transmission system provided by the embodiment of the present invention;

[0031] Figure 8 The primary and secondary currents of the transformer of the distributed energy consumption device of the flexible direct current transmission system provided in the embodiment of the present invention.

[0032] In the attached drawings: 1—AC power supply, 2—transformer, 3—rectifier circuit, 7—first test valve section, 8—second test valve section, 9—energy supplement module, 12—distributed energy consumption valve section;

[0033] Figures 2 to 8 In the figure, the horizontal axis is time in seconds. DETAILED DESCRIPTION

[0034] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Reference Figure 1 A test device topology for a distributed energy consumption device of a flexible direct current transmission system comprises a distributed energy consumption valve section 8, a first test valve section 7, a second test valve section 8, an energy compensation module 9, a load inductor L1, a current limiting inductor L2, a current limiting resistor R1, an AC power supply 1, a transformer T, a rectifier circuit 3, a charging circuit switch S1, an energy compensation module switch S2 and an energy compensation diode D2; the distributed energy consumption valve section 12 of the topology comprises 6 cascaded distributed energy consumption modules; the first test valve section and the second test valve section both comprise 6 cascaded power modules, and the power modules are full-bridge modules or half-bridge modules; the half-bridge module comprises a capacitor C, an IGBT T71 and an IGBT T72, and a diode D is connected in anti-parallel at both ends of the IGBT T71 and the IGBT T72, the emitter of the IGBT T71 is connected to the collector of the IGBT T72, and the capacitor C is connected in parallel at both ends of the branch formed by the two IGBTs.

[0036] The AC power supply, transformer, rectifier circuit, charging switch, current limiting resistor, load inductor, first test valve section, second test valve section, energy replenishment module 9, energy replenishment diode D2, and energy replenishment switch constitute a typical valve section towing platform, and the distributed energy consumption valve section to be tested and the current limiting inductor are connected in series and then bridged between the first test valve section and the second test valve section. The energy replenishment module 9 includes capacitor C9, IGBT T91 and IGBT T92, and diodes D91 and D92 are respectively connected in anti-parallel at both ends of IGBT T91 and IGBT T92, and the emitter of IGBT T91 is connected to the collector of IGBT T92, and capacitor C9 is connected in parallel at both ends of the branch formed by IGBT T91 and IGBT T92.

[0037] The AC power supply 1 of the test device is converted into a DC voltage through a transformer T and a rectifier circuit 3; the first test valve section 7 of the test device forms a first branch, the second test valve section 8 and the energy compensation module 9 are connected in series to form a second branch, and the distributed energy consumption valve section 12 and the current limiting inductor L2 are connected in series to form a third branch. After the first branch and the third branch are connected in parallel, they are connected in parallel with the second branch through the load inductor L1, and then connected in parallel to the DC side of the rectifier circuit 3 through the current limiting resistor R1 and the charging switch S1; the capacitor C9 of the energy compensation module 9 of the test device is connected in parallel to the DC side of the rectifier circuit through the energy compensation diode D2 and the energy compensation switch S2. The transformer is a step-up split transformer, the primary side of the transformer can use low-voltage conventional electricity (380V), and the secondary transformer of the transformer must use higher voltage electricity to meet the voltage requirements of the test platform. The split transformer can raise the voltage by voltage superposition; the AC side of the rectifier circuit is connected in parallel, and the DC side of the rectifier circuit is connected in series.

[0038] A test method for distributed energy consumption devices in a flexible direct current transmission system is divided into four stages: an uncontrolled charging stage, a cyclic charging stage, an unlocked operation voltage and current boosting stage, and a steady-state pressure equalization stage. The distributed energy consumption valve section 12 is energized synchronously with the test valve section. When the two test valve sections are unlocked and operated, the distributed energy consumption valve section carries out a steady-state pressure equalization test as required.

[0039] In the uncontrolled charging stage, the voltage of the AC power supply is evenly distributed to each module of the two test valve sections and the distributed energy consumption valve section. The module capacitor voltage must ensure that the energy source is reliably charged;

[0040] In the cycle charging stage, the power supply charges the two test valve sections and the energy replenishment module one-to-one;

[0041] During the boost and current stage of unlocking operation, the voltages of the two test valve sections are industrial frequency sinusoidal voltages with positive bias. When the port voltage of any test valve section is higher than the sum of the voltages of the distributed energy consumption modules of the distributed energy consumption valve section, the energy consumption module is charged; when the port voltage of any test valve section is lower than the sum of the module voltages of the distributed energy consumption valve section, the flow-through diode D1 in the distributed energy consumption module is cut off due to the reverse pressure, and the distributed energy consumption valve section does not discharge any test valve section; the port voltage of the first test valve section only includes the port voltage of the first test valve section, and the port voltage of test valve section 2 is the sum of the voltages of the second test valve section and the energy replenishment module 9.

[0042] In the steady-state pressure equalization stage, when the voltage of the distributed energy consumption module of the distributed energy consumption valve section is higher than the upper limit of the set value, the high-voltage energy consumption module discharges through the energy consumption resistor R1, and stops discharging when the voltage of the energy consumption module discharges to the lower limit of the set value. The cycle is repeated to simulate the steady-state pressure equalization test of the distributed energy consumption valve section.

[0043] A test method for a distributed energy consumption device of a flexible direct current transmission system comprises the following steps:

[0044] Step 1, in the uncontrolled charging stage, disconnect the energy replenishment module switch S2, close the charging switch S1, raise the AC power supply voltage, and perform uncontrolled charging. The current limiting resistor R1 limits the charging circuit current so that the current is not too large during the charging process to protect the test equipment; raise the module voltage of the two test valve sections until the energy source can be stably charged. At this time, the first test valve section and the second test valve section are connected in series with the energy replenishment module 9 and the distributed energy consumption valve section 12 in parallel, and the modules of the three valve sections each evenly distribute the voltage output by the rectifier circuit;

[0045] Step 2, during the cycle charging stage, the AC power supply voltage is reduced so that the output voltage of the rectifier circuit is the same as the voltage of the first test valve section module. The two test valve sections are switched to a one-to-one cycle charging mode. At this time, the port voltage of the two test valve sections is lower than the sum of the voltages of the distributed energy consumption valve section modules. The through-current diode D1 in the distributed energy consumption module is cut off due to the reverse pressure. The two test valve sections do not charge the distributed energy consumption valve section modules. The distributed energy consumption modules are in a self-discharge state, and the voltage of the distributed energy consumption modules remains basically unchanged for a short time. During the cycle charging stage, the power supply voltage will drop to facilitate the next unlocking stage and reduce the impact of the unlocking moment. The main purpose is to ensure that the entire system can proceed smoothly. A large impact will endanger the safety of the equipment.

[0046] Step 3, unlock and run the boost and current stage, disconnect the charging circuit switch S1, close the energy replenishment module switch S2, unlock and run the two test valve sections, synchronously control the AC power supply voltage and the phase angle slope between the two test valve sections to increase the two test valve section module voltages, the distributed energy consumption module voltage and the load inductor L1 current to the set value. When the port voltage of any test valve section is higher than the sum of the distributed energy consumption module voltages, in order to prevent current shock, the current limiting inductor L2 is used to limit the charging current of the distributed energy consumption valve section;

[0047] Step 4, steady-state pressure equalization stage, after the two test valve sections operate stably, enable the pressure equalization control strategy of the distributed energy-consuming valve section and carry out a steady-state pressure equalization test.

[0048] Figure 2~Figure 8 The simulation results provided for the embodiments of the present invention are divided into four stages, namely, the uncontrolled charging stage, the cyclic charging stage, the unlocked operation boosting and current increasing stage and the steady-state voltage equalization stage. The four stages are described in turn below.

[0049] 0~0.5s is the uncontrolled charging stage. The charging circuit switch S1 is closed, and the energy replenishment module switch S2 is disconnected to raise the power supply voltage so that the output voltage of the rectifier circuit is 3kV, the module voltage of the first test valve section is 0.5kV, and the module voltage of the distributed energy consumption valve section is 0.5kV. Since the second test valve section is cascaded with the energy replenishment module 9, the module voltage is 0.43kV. Before the end of the uncontrolled charging, the AC power supply voltage is adjusted to reduce the output voltage of the rectifier circuit to 0.5kV.

[0050] 0.5~2s is the cycle charging stage. The cycle charging is that the power supply charges the two test valve sections and the energy replenishment module one-to-one. The module voltage of the first test valve section is basically equivalent to the voltage of the rectifier circuit. The module voltage of the first test valve section is basically maintained at 0.5kV. The module voltage of the second test valve section and the energy replenishment module is lower than the rectifier current voltage, which will raise the module voltage of the second test valve section and the energy replenishment module to 0.5kV.

[0051] 2~8s is the unlocking operation boosting and current raising stage, which synchronously controls the AC power supply voltage and the phase angle slope between the two test valve sections to increase the voltage of the two test valve section modules, the voltage of the distributed energy consumption module and the voltage of the energy replenishment module 9 to 2.1kV;

[0052] 8~20s is the steady-state voltage equalization stage, in which the distributed energy consumption valve section control strategy is not enabled for 8~12s, and the module voltage of the distributed energy consumption valve section is about 2.1kV. After 12s, the distributed energy consumption valve section control strategy is enabled, and the voltage setting value of the distributed energy consumption module is maintained at 2.1kV for 12~14s, and the voltage setting value of the distributed energy consumption module is changed to 2.0kV for 14~16s, and the voltage setting value of the distributed energy consumption module is changed to 1.9kV for 16~18s, and the voltage setting value of the distributed energy consumption module is changed to 1.8kV for 18~20s; when the voltage of a distributed energy consumption module is higher than the set value by 1.05 times, the energy discharge branch of the distributed energy consumption module is put into operation, and the energy discharge branch includes IGBT T12, diode D12 and energy dissipation resistor R12, disconnect the energy dissipation branch when the module voltage drops to 0.95 times the set value, and the voltage of the distributed energy consumption module is maintained in the range of 0.95~1.05 times the set value, which reflects the steady-state voltage equalization capability of the distributed energy consumption device; as the voltage setting value of the energy consumption module decreases, the maximum voltage of the two test valve section ports, the voltage of the two test valve section modules, the voltage of the energy compensation module and the load inductance current all decrease, which reflects the ability of the distributed energy consumption device to suppress DC voltage; as the voltage setting value of the energy consumption module decreases, the current of the distributed energy consumption device, the power of the power supply, and the primary and secondary currents of the transformer increase, which reflects the energy consumption capacity of the distributed energy consumption device.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit it. A person skilled in the art should understand that a person skilled in the art may modify or replace the specific implementation of the present invention, such as replacing the half-bridge module in the test valve section with a full-bridge module, a clamped twin module, etc., but these modifications or changes are within the scope of protection of the pending claims.

Claims

1. A test method for distributed energy consumption devices in a flexible DC transmission system. It is characterized in that The test method is based on a test device for a distributed energy consumption device of a flexible direct current power transmission system, the test device for a distributed energy consumption device of a flexible direct current power transmission system comprising a first test valve section (7), a second test valve section (8), an energy replenishment module (9), a load inductor L1, a current limiting inductor L2, an AC power supply, a transformer T, a rectifier circuit (3), a charging circuit switch S1 and an energy replenishment module switch S2; the first test valve section (7) and the second test valve section (8) both comprise a plurality of cascaded power modules; The AC power source is converted into a DC voltage via a transformer T and a rectifier circuit (3); the first test valve section (7) forms a first branch; the second test valve section (8) is connected in series with an energy replenishment module (9) to form a second branch; the distributed energy consumption valve section (12) to be tested is connected in series with a current limiting inductor L2 to form a third branch; the first branch and the third branch are connected in parallel and then connected in parallel with the second branch via a load inductor L1 to form a parallel branch; the parallel branch is then connected in parallel to the DC side of the rectifier circuit (3) via a charging switch S1; the energy replenishment module (9) is connected in parallel to the DC side of the rectifier circuit via an energy replenishment diode D2 and an energy replenishment switch S2; The test method comprises the following steps: Step 1, uncontrolled charging stage: disconnect the energy replenishment module switch S2, close the charging switch S1, raise the AC power supply voltage, perform uncontrolled charging, raise the module voltage of the two test valve sections until the energy source can be stably charged, at this time, the first test valve section and the second test valve section are connected in series with the energy replenishment module (9) and the distributed energy consumption valve section (12) in a parallel wiring mode, and the modules of the three valve sections each evenly distribute the voltage output by the rectifier circuit; the distributed energy consumption valve section (12) includes a cascaded distributed energy consumption module, the distributed energy consumption module includes an energy discharge branch, the energy discharge branch includes an IGBT T12, a diode D12 and an energy discharge resistor R12, and the parallel branch formed by the parallel connection of the IGBT T12 and the diode D12 is connected in series with the energy discharge resistor R12; Step 2, cycle charging stage: reduce the voltage of the AC power supply so that the output voltage of the rectifier circuit is the same as the voltage of the first test valve section module, and the first test valve section and the second test valve section are switched to a one-to-one cycle charging mode. At this time, the port voltages of the two test valve sections are lower than the sum of the voltages of the distributed energy consumption valve section modules. The flow diode D1 in the distributed energy consumption module is cut off due to the reverse pressure. The two test valve sections do not charge the distributed energy consumption valve section modules. The distributed energy consumption modules are in a self-discharge state, and the voltage of the distributed energy consumption modules remains basically unchanged for a short time. Step 3, unlocking and running the boosting and current raising stage: disconnect the charging circuit switch S1, close the energy replenishment module switch S2, unlock the two test valve sections for operation, synchronously control the AC power supply voltage and the phase angle slope between the two test valve sections to increase the module voltage of the first test valve section and the second test valve section, the voltage of the distributed energy consumption module and the current of the load inductor L1 to the set value; Step 4, steady-state pressure equalization stage: when the voltage of the distributed energy consumption module of the distributed energy consumption valve section is higher than the upper limit of the set value, the energy discharge branch of the distributed energy consumption module is put into operation, and the high-voltage energy consumption module is discharged through the energy discharge resistor R12, and the discharge is stopped when the voltage of the energy consumption module is discharged to the lower limit of the set value; the cycle is repeated to simulate the steady-state pressure equalization test of the distributed energy consumption valve section; the voltage setting value of the energy consumption module is gradually reduced to test the ability of the distributed energy consumption device to suppress the DC voltage.

2. A test method for a distributed energy consumption device of a flexible direct current transmission system according to claim 1, It is characterized in that The power module comprises a capacitor C and two IGBTs. A diode D is connected in anti-parallel at both ends of the two IGBTs. The capacitor C is connected in parallel at both ends of a branch formed by connecting the two IGBTs.

3. A test method for a distributed energy consumption device of a flexible direct current transmission system according to claim 1, It is characterized in that The energy compensation module (9) comprises a capacitor C9, an IGBT T91 and an IGBT T92, wherein a diode D91 and a diode D92 are respectively connected in anti-parallel at both ends of the IGBT T91 and the IGBT T92, and the capacitor C9 is connected in parallel at both ends of a branch formed by connecting the IGBT T91 and the IGBT T92.

4. A test method for distributed energy consumption devices in a flexible DC transmission system according to claim 3, It is characterized in that The capacitor C9 of the energy compensation module (9) is connected in parallel to the DC side of the rectifier circuit via the energy compensation diode D2 and the energy compensation switch S2.

5. A test method for distributed energy consumption devices in a flexible DC transmission system according to claim 1, It is characterized in that The transformer T is a step-up split transformer.

6. A test method for a distributed energy consumption device of a flexible direct current transmission system according to claim 1, It is characterized in that A current limiting resistor R1 is connected between the parallel branch and the charging switch S1.

7. A test method for distributed energy consumption devices in a flexible DC transmission system according to claim 1, It is characterized in that In step 4, the voltage setting value of the energy consumption module is gradually reduced at a rate of 0.1 kV per second.

Images