A circuit for current turn-off test of a converter valve and a control method thereof

Abstract

This invention relates to a current-shutdown test circuit and its control method for a converter valve, belonging to the field of high-voltage power transmission technology. The circuit includes a voltage source system, a current source system, an auxiliary valve, and an inrush current loop. The inrush current loop includes a reactor and a capacitor connected in series. The output terminal of the voltage source system, the high-voltage terminal of the auxiliary valve, the high-voltage terminal of the inrush current loop, and the output terminal of the current source system are connected sequentially. The ground terminal of the voltage source system, the low-voltage terminal of the auxiliary valve, the low-voltage terminal of the inrush current loop, and the ground terminal of the current source system are connected. A line between the high-voltage terminal of the auxiliary valve and the high-voltage terminal of the inrush current loop is used to connect the high-voltage terminal of the test valve. The method involves the voltage source system and the current source system applying voltage and current to the test valve through a combined test operation mode, while the inrush current loop applies an inrush current to the test valve. This invention constructs a test circuit equivalent to actual operating conditions, capable of reliably completing the current-shutdown test of the converter valve.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage power transmission technology, specifically relating to a converter valve current shut-off test circuit and its control method. Background Technology

[0002] In recent years, due to the development of ultra-high voltage direct current (UHVDC) transmission technology, UHVDC transmission projects using thyristor converter valves have played a crucial role in my country. Traditional UHVDC transmission projects using thyristor converter valves have advantages such as mature technology, low loss, and high reliability, playing a vital role in large-capacity, long-distance power transmission. However, there is a risk of commutation failure on the inverter side of these projects. Unreliable converter valve performance is a significant cause of commutation failure on the inverter side. Therefore, it is necessary to design a test circuit to test the operating conditions of the inverter-side converter valves to verify their reliability under high-current operating conditions.

[0003] However, existing converter valve current shutdown tests make it difficult to construct test circuits in the test environment that are equivalent to actual operating conditions, resulting in inaccurate test results and failing to guarantee the reliable operation of the converter valve. Summary of the Invention

[0004] The purpose of this invention is to provide a converter valve current shut-off test circuit and its control method to solve the problem of unreliability of existing converter valve current shut-off test circuits.

[0005] The technical solution provided by this invention for the converter valve current shut-off test circuit to solve the above-mentioned technical problems is as follows: The circuit includes a voltage source system, an auxiliary valve, an inrush current loop, and a current source system; the inrush current loop includes a capacitor and a reactor connected in series; the output terminal of the voltage source system, the high-voltage terminal of the auxiliary valve, the high-voltage terminal of the inrush current loop, and the output terminal of the current source system are connected in sequence; the ground terminal of the voltage source system, the low-voltage terminal of the auxiliary valve, the low-voltage terminal of the inrush current loop, and the ground terminal of the current source system are connected; an interface for connecting the high-voltage terminal of the test valve is provided on the connection line between the high-voltage terminal of the auxiliary valve and the high-voltage terminal of the inrush current loop.

[0006] The beneficial effects of the test circuit of this invention are: this invention constructs a test circuit equivalent to the actual operating conditions, which can complete the current shut-off test of the converter valve, and the test results are more reliable.

[0007] Furthermore, during the test, when the impulse current loop applies impulse current to the test valve, in order to prevent it from interfering with the current source system and to facilitate the control of the current applied to the test valve, the interface used to connect the high-voltage end of the test valve is connected to the high-voltage end of the impulse current loop through a first controllable switch, and the high-voltage end of the impulse current loop is connected to the output end of the current source system through a second controllable switch.

[0008] To facilitate the formation of a controllable inrush current, the inrush current circuit also includes a third controllable switch, which is connected in series with a capacitor and a reactor.

[0009] After the current cut-off test is completed, in order to dissipate the excess electrical energy in the inrush current loop and ensure safety, a diode is connected in parallel with the reactor.

[0010] Furthermore, in order to power the test valve, the auxiliary valve is used to connect the high-potential energy harvesting plate of the test valve through a damping circuit.

[0011] Furthermore, in order to ensure the reliability of the output current of the current source system, the current source system includes a six-pulse converter operating back-to-back.

[0012] Furthermore, the test valve is an IGCT switching valve, which includes multiple IGCT devices connected in series.

[0013] The technical solution for the converter valve current shut-off test circuit provided by the present invention to solve the above-mentioned technical problems is as follows: The method includes the following steps:

[0014] 1) Set the voltage and current parameters, start the voltage source system and current source system, lock the test valve, and open the auxiliary valve;

[0015] 2) When the voltage across the sample valve reaches the preset charging threshold, the sample valve is triggered to open and the auxiliary valve is locked.

[0016] 3) Control the impulse current circuit to generate impulse current and apply the impulse current to the test valve, while simultaneously locking the voltage source system and the current source system;

[0017] 4) When the impact current is detected to meet the test valve shut-off current threshold, the test valve is controlled to shut off.

[0018] The beneficial effects of the control method of the present invention are: the present invention can complete the current shut-off test of the converter valve, and the test results are more reliable.

[0019] Furthermore, in order to meet different test requirements, different voltages and currents are applied to the auxiliary thyristor valve and IGCT converter valve by adjusting the control timing of the voltage source system and the current source system.

[0020] Furthermore, in order to meet different test requirements, the peak value of the inrush current is adjusted by adjusting the amount of electricity released by the capacitor, and the duration of the inrush current is adjusted by adjusting the reactance of the reactor and the capacitance of the capacitor. Attached Figure Description

[0021] Figure 1This is a circuit diagram of the converter valve current shut-off test circuit according to an embodiment of the present invention;

[0022] Figure 2 This is a circuit diagram of a test circuit for an IGCT converter valve current shut-off test according to an embodiment of the present invention.

[0023] Figure 3 Waveforms of the test voltage and test current for the IGCT converter valve current shut-off test;

[0024] Figure 4 The waveforms of the test current and control voltage for the short-circuit current test of the IGCT converter valve are shown. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0026] Embodiment of the Current Shutdown Test Circuit for the Converter Valve of the Present Invention

[0027] like Figure 1 As shown, the test circuit of this embodiment includes a voltage source system, a current source system, an auxiliary valve, and an impulse current loop. The impulse current loop includes a capacitor Cs and a reactor Ls connected in series. The output terminal of the voltage source system, the high-voltage terminal of the auxiliary valve, the high-voltage terminal of the impulse current loop, and the output terminal of the current source system are connected sequentially. The ground terminal of the voltage source system, the low-voltage terminal of the auxiliary valve, the low-voltage terminal of the impulse current loop, and the ground terminal of the current source system are connected. An interface for connecting the high-voltage terminal of the test sample valve is provided on the connection line between the high-voltage terminal of the auxiliary valve and the high-voltage terminal of the impulse current loop.

[0028] During the test, when the impulse current loop applies an impulse current to the test valve, a second controllable switch is installed on the connection line between the output terminal of the current source system and the high-voltage terminal of the impulse current loop to ensure that it does not interfere with the current source system. This second controllable switch is turned off when the impulse current loop applies an impulse current to the test valve. To facilitate control of the current applied to the test valve, a first controllable switch is installed between the test valve inlet and the impulse current loop. For example... Figure 1 As shown, when the test valve is connected, the output terminal of the current source system is connected to the high-voltage terminal of the test valve via the second controllable switch and the first controllable switch, and the grounding terminal of the current source system is connected to the low-voltage terminal of the test valve.

[0029] In this embodiment, the inrush current circuit uses an oscillating circuit composed of a capacitor Cs and a reactor Ls connected in series. To facilitate the formation of a controllable inrush current, the inrush current circuit also includes a third controllable switch, which is connected in series with the capacitor Cs and the reactor Ls. Figure 1As shown, when the test valve is connected, the high-voltage terminal of capacitor Cs is connected to the high-voltage terminal of the test valve via reactor Ls, the third controllable switch, and the first controllable switch. The ground terminal of capacitor Cs is connected to the low-voltage terminal of the test valve. After capacitor Cs has finished charging, by controlling the conduction of the third controllable switch, the capacitor discharges to form an inrush current.

[0030] After the current cut-off test is completed, in order to ensure safety, it is necessary to consume the excess electrical energy in the impact current circuit. To this end, the present invention connects a diode valve Vs4 in parallel with the reactor Ls, and the cathode of the diode valve Vs4 is connected to the high voltage terminal of the capacitor Cs.

[0031] In a preferred embodiment, the present invention utilizes the voltage across the auxiliary valve to power the test valve. Therefore, the auxiliary valve is connected in series with the high-potential power extraction board of the test valve via a damping circuit. During the experiment, the auxiliary thyristor valve is first turned on, and the test valve assembly is locked. The voltage across the auxiliary valve helps the test valve extract power. When the voltage of the power supply board for the test valve reaches a preset charging threshold, the test valve assembly is then triggered to turn on, and the auxiliary valve assembly is locked.

[0032] In a preferred embodiment, the current source system of the present invention includes a back-to-back 6-pulse converter, with the test valve serving as one arm of the 6-pulse bridge to provide the required current to the test valve during the test. The voltage source system is selected to have a fast adjustment speed, enabling continuous adjustment from low to high voltage.

[0033] In a preferred embodiment, the first, second, and third controllable switches can be thyristors, and the auxiliary valve is a thyristor valve. The IGCT converter valve comprises multiple IGCT devices connected in series, possessing advantages such as low driving power, simple driving circuit, high blocking voltage, large capacity, low on-state loss, high reliability, high withstand voltage, large current, low manufacturing cost, and high yield. It is frequently used in converter valves in high-voltage direct current transmission projects, and the test circuit of this invention is particularly suitable for current-shutdown tests of IGCT converter valves.

[0034] Embodiment of the control method for the current shut-off test circuit of the converter valve of the present invention

[0035] This embodiment provides a control method for the aforementioned converter valve current shut-off test circuit. When a test valve is connected and a shut-off test is performed, the control method includes the following steps:

[0036] 1) Set the voltage and current parameters, start the voltage source system and current source system, lock the test valve, and open the auxiliary valve;

[0037] 2) When the voltage across the sample valve reaches the preset charging threshold, the sample valve is triggered to open and the auxiliary valve is locked.

[0038] 3) Control the impulse current circuit to generate impulse current and apply the impulse current to the test valve, while simultaneously locking the voltage source system and the current source system;

[0039] 4) When the impact current is detected to meet the test valve shut-off current threshold, the test valve is controlled to shut off.

[0040] When the voltage source system and current source system are started, the auxiliary valve of the voltage source system is turned on, and a combined voltage and current are applied to the auxiliary valve. The voltage across the auxiliary valve helps the test valve to obtain energy. When the voltage of the power supply board for the test valve reaches the preset charging threshold, the test valve assembly is triggered to turn on, and the auxiliary valve assembly is locked. After the capacitor Cs is fully charged, the conduction time of the third controllable switch is controlled. An oscillation circuit is formed through the capacitor Cs and reactor Ls, applying a positive short-circuit current to the test valve. At this time, the voltage source system and current source system are locked. When the short-circuit current detected on the test valve meets the shutdown current value, the background control turns off the test valve, and the test valve current shutdown test is completed. The residual current on the reactor Ls is released through the diode valve Vs4.

[0041] To regulate the voltage and current applied to the auxiliary valve and the test valve, the timing of the voltage and current sources is adjusted. The peak value of the inrush current can be adjusted by regulating the system energy released by capacitor Cs, and the duration of the inrush current release can be adjusted by regulating the reactance of reactor Ls and the capacitance of capacitor Cs.

[0042] The technical solution of the present invention will be described in detail below by taking the application of the experimental circuit in the current turn-off test of the IGCT converter valve.

[0043] like Figure 2 As shown, the test circuit for the current turn-off test of the IGCT converter valve includes a voltage source system, a current source system, an auxiliary thyristor valve Vt, an IGCT converter valve, a first thyristor valve Vs1, a second thyristor valve Vs2, a third thyristor valve Vs3, a reactor Ls, a diode valve Vs4, and a short-circuit capacitor Cs.

[0044] The high-pressure end of the auxiliary thyristor valve Vt is connected to the high-pressure end of the IGCT converter valve, and the low-pressure end of the auxiliary thyristor valve Vt is connected to the low-pressure end of the IGCT converter valve.

[0045] The output terminal of the voltage source system is connected to the high-voltage terminal of the IGCT converter valve, and the ground terminal of the voltage source system is connected to the low-voltage terminal of the IGCT converter valve. The voltage source system can provide a voltage source with fast adjustment speed and can realize continuous adjustment from low voltage to high voltage for the test.

[0046] The output of the current source system is connected to the high-voltage end of the IGCT converter valve in sequence through the second thyristor valve Vs1 and the first thyristor valve Vs2. The grounding end of the current source system is connected to the low-voltage end of the IGCT converter valve. The current source system provides the required current to the IGCT converter valve during the test according to the experimental requirements through a 6-pulse converter that operates back to back. The IGCT converter valve serves as one arm of the 6-pulse bridge that constitutes the current source.

[0047] The high-voltage terminal of the short-circuit capacitor Cs is connected to the high-voltage terminal of the IGCT converter valve via reactor Ls, third thyristor valve Vs3, and first thyristor valve Vs1. Diode valve Vs4 is connected in parallel with the reactor, and its cathode is connected to the high-voltage terminal of the short-circuit capacitor Cs. The ground terminal of the short-circuit capacitor Cs is connected to the low-voltage terminal of the IGCT converter valve.

[0048] The control method for the test circuit used in the IGCT converter valve current turn-off test includes the following steps:

[0049] Step 1: Set voltage and current parameters, start the voltage and current source systems, lock the IGCT converter valve, turn on the auxiliary thyristor valve Vt, turn on the first thyristor valve Vs1 and the second thyristor valve Vs2, turn off the third thyristor valve Vs3, and apply the combined voltage and current to the auxiliary thyristor valve Vt, such as... Figure 3 As shown;

[0050] Step 2: When the voltage of the IGCT power supply board reaches the preset charging threshold, the IGCT valve assembly is triggered to conduct, the auxiliary thyristor valve Vt is locked, and a combined voltage and current are applied to the IGCT converter valve, such as... Figure 3 As shown;

[0051] Step 3: Charge the short-circuit capacitor Cs. After charging is complete, by controlling the conduction time of the third thyristor valve Vs3, an oscillation circuit is formed through the short-circuit capacitor Cs and the reactor Ls, applying a positive short-circuit current to the IGCT converter valve. At this time, the voltage source system and the current source system are locked, and the second thyristor valve Vs2 is turned off. Figure 4 As shown;

[0052] Step 4: When the short-circuit current detected on the IGCT converter valve meets the shutdown current value, the background control shuts down the IGCT converter valve, such as... Figure 4 As shown. The IGCT converter valve current shut-off test is completed, and the residual current on reactor Ls is released through diode valve Vs4.

Claims

1. A current shut-off test circuit for a converter valve, characterized in that, The circuit includes a voltage source system, an auxiliary valve, an inrush current loop, and a current source system. The inrush current loop includes a capacitor and a reactor connected in series. The output terminal of the voltage source system, the high-voltage terminal of the auxiliary valve, the high-voltage terminal of the inrush current loop, and the output terminal of the current source system are connected sequentially. The ground terminal of the voltage source system, the low-voltage terminal of the auxiliary valve, the low-voltage terminal of the inrush current loop, and the ground terminal of the current source system are connected. An interface for connecting the high-voltage terminal of the test valve is provided on the connection line between the high-voltage terminal of the auxiliary valve and the high-voltage terminal of the inrush current loop. The ground terminal of the current source system is used to connect the low-voltage terminal of the test valve. This circuit is used to implement a current shut-off test of the converter valve. In this test, when the voltage source system and the current source system are started, the test valve is locked and the auxiliary valve is opened. When the voltage of the power supply board of the test valve reaches a preset charging threshold, the test valve is opened and the auxiliary valve is locked. While applying an inrush current to the test valve, the voltage source system and the current source system are locked. When the inrush current meets the test valve shut-off current threshold, the test valve is shut off.

2. The converter valve current shut-off test circuit according to claim 1, characterized in that, The interface for connecting the high-pressure end of the test sample valve is connected to the high-pressure end of the impact current circuit via a first controllable switch, and the high-pressure end of the impact current circuit is connected to the output end of the current source system via a second controllable switch.

3. The converter valve current shut-off test circuit according to claim 1, characterized in that, The inrush current circuit also includes a third controllable switch, which is connected in series with the capacitor and the reactor.

4. The converter valve current shut-off test circuit according to claim 3, characterized in that, A diode is connected in parallel with the reactor.

5. The converter valve current shut-off test circuit according to claim 1, characterized in that, The auxiliary valve is used to connect the high-potential energy harvesting plate of the sample valve through a damping circuit.

6. The converter valve current shut-off test circuit according to claim 1, characterized in that, The current source system includes six pulse converters operating back-to-back.

7. The converter valve current shut-off test circuit according to any one of claims 1 to 6, characterized in that, The test valve is an IGCT converter valve, which includes multiple IGCT devices connected in series.

8. A control method for a converter valve current shut-off test circuit, characterized in that, The converter valve current shut-off test circuit includes a voltage source system, an auxiliary valve, an impulse current loop, and a current source system. The impulse current loop includes a capacitor and a reactor connected in series. The output terminal of the voltage source system, the high-voltage terminal of the auxiliary valve, the high-voltage terminal of the impulse current loop, and the output terminal of the current source system are connected sequentially. The ground terminal of the voltage source system, the low-voltage terminal of the auxiliary valve, the low-voltage terminal of the impulse current loop, and the ground terminal of the current source system are connected. An interface for connecting the high-voltage terminal of the test valve is provided on the connection line between the high-voltage terminal of the auxiliary valve and the high-voltage terminal of the impulse current loop. The ground terminal of the current source system is used to connect the low-voltage terminal of the test valve. The method includes the following steps: 1) Set the voltage and current parameters, start the voltage source system and current source system, lock the test valve, and open the auxiliary valve; 2) When the voltage of the power supply board for the test valve reaches the preset charging threshold, the test valve is triggered to open and the auxiliary valve is locked. 3) Control the impulse current circuit to generate impulse current, and apply the impulse current to the test valve, while simultaneously locking the voltage source system and the current source system; 4) When the impact current is detected to meet the test valve shut-off current threshold, the test valve is controlled to shut off.

9. The control method for the converter valve current shut-off test circuit according to claim 8, characterized in that, By adjusting the control timing of the voltage source system and the current source system, different voltages and currents are applied to the auxiliary thyristor valve and the IGCT converter valve.

10. The control method for the converter valve current shut-off test circuit according to claim 8, characterized in that, The peak value of the inrush current is adjusted by regulating the amount of electricity released by the capacitor, and the duration of the inrush current is adjusted by regulating the reactance of the reactor and the capacitance of the capacitor.

11. The control method for the converter valve current shut-off test circuit according to claim 8, characterized in that, The interface for connecting the high-pressure end of the test sample valve is connected to the high-pressure end of the impact current circuit via a first controllable switch, and the high-pressure end of the impact current circuit is connected to the output end of the current source system via a second controllable switch.

12. The control method for the converter valve current shut-off test circuit according to claim 8, characterized in that, The inrush current circuit also includes a third controllable switch, which is connected in series with the capacitor and the reactor.

13. The control method for the converter valve current shut-off test circuit according to claim 12, characterized in that, A diode is connected in parallel with the reactor.

14. The control method for the converter valve current shut-off test circuit according to claim 8, characterized in that, The auxiliary valve is used to connect the high-potential energy harvesting plate of the sample valve through a damping circuit.

15. The control method for the converter valve current shut-off test circuit according to claim 8, characterized in that, The current source system includes six pulse converters operating back-to-back.

16. The control method for the converter valve current shut-off test circuit according to any one of claims 8 to 15, characterized in that, The test valve is an IGCT converter valve, which includes multiple IGCT devices connected in series.

Images