Low voltage equivalent test device for reverse recovery period protection function of converter valve control unit

Abstract

The application discloses a low-voltage equivalent testing device for reverse recovery period protection function of a converter valve control unit, and belongs to the technical field of testing of the converter valve control unit. The device comprises a low-voltage module, a voltage dividing unit, a main control unit and a synchronous voltage acquisition unit. The low-voltage module is connected with the converter valve control unit to be tested through the voltage dividing unit. The synchronous voltage acquisition unit is connected with the voltage dividing unit in parallel. The converter valve control unit to be tested, the voltage dividing unit and the synchronous voltage acquisition unit are connected with the main control unit. The synchronous voltage acquisition unit acquires the voltage across the voltage dividing unit and sends the voltage information to the main control unit. The application solves the defects that the testing of the reverse recovery period protection function of the thyristor control unit needs to be connected with the thyristor and the damping loop and needs to be tested by using high voltage, and improves the testing efficiency and safety.

Description

Technical Field

[0001] This invention relates to the field of converter valve control unit testing technology, specifically a low-pressure equivalent testing device for the reverse recovery period protection function of a converter valve control unit. Background Technology

[0002] The converter valve in a high-voltage direct current (HVDC) transmission line is a core component of the converter station, and the high-potential trigger monitoring board of the converter valve, as its "heart," primarily functions to achieve photoelectric conversion of signals between the valve control and the converter valve, and to perform functions such as triggering, protecting, and monitoring the status of the converter valve. Its status and performance are crucial to the safe and reliable operation of the entire HVDC transmission system. Therefore, testing the converter valve control unit is of great significance for ensuring the safe and stable operation of the HVDC transmission system.

[0003] During the turn-off process, a thyristor only gains the ability to withstand reverse voltage after the current drops from its rated value to zero. Due to the junction capacitance of the thyristor, a certain amount of reverse recovery charge is required to allow the current to flow in the reverse direction after crossing zero; this process is called the reverse recovery period. During this period, charge carriers called recovery charges exist within the thyristor. If the PN junction of the thyristor cannot dissipate these charge carriers in time, it may cause local overheating and damage, or lead to the thyristor's re-triggered state, resulting in further damage. Testing the reverse recovery period protection function of the converter valve control unit can effectively prevent the thyristor from being damaged during the reverse recovery period.

[0004] Patent document CN 115826557 A discloses a testing device for a converter valve thyristor control unit, including a main control module, a pulse timing module, a simulated impulse voltage module, and a sampling module. The simulated impulse voltage module is connected to the main control module to generate an impulse voltage according to the instructions of the main control module, and is used to connect to the thyristor control unit under test to transmit the generated impulse voltage to the thyristor control unit under test to test its protection triggering function. The simulated impulse voltage module includes an energy storage capacitor and an inductor. The energy storage capacitor is connected in series with a power supply, and the inductor is connected in series at the output terminal of the capacitor to output the impulse voltage. The main control module is used to send instructions to the simulated impulse voltage module according to the voltage of the energy storage capacitor, and also to judge the test results of the protection triggering function of the thyristor control unit under test based on the received signal. This is beneficial for the debugging and analysis of the thyristor control unit. However, this invention uses impulse voltage for testing, which has poor safety.

[0005] Patent document CN 115656682 A discloses a testing device and method for a converter valve thyristor control unit, comprising: a thyristor-level testing system, with a main control unit connected to a high-frequency signal output unit, an analog signal acquisition unit, an optical interface, and a communication interface; the high-frequency signal output unit connected to the thyristor stage under test (TD) for applying a test signal to the TD; the optical interface connected to the TD for applying an optical pulse test signal to the TD; the analog signal acquisition unit connected to the TD for acquiring the test feedback signal of the TD; a polarity control signal simulation system for providing a polarity control signal to the converter valve under test; and a feedback signal simulation system for providing a feedback signal to the converter valve under test. This invention, by applying different test signals to the corresponding converter valve interfaces using the thyristor-level testing system, the polarity control signal simulation system, and the feedback signal simulation system, can achieve multi-functional testing of various converter valve thyristor control units. However, this invention also employs a high-voltage testing method, thus failing to solve the aforementioned technical problems. Summary of the Invention

[0006] In view of this, the present invention addresses the shortcomings of the prior art by providing a low-voltage equivalent test device for the reverse recovery period protection function of a converter valve control unit, which solves the defects of the current method of testing the reverse recovery period protection function of a thyristor control unit, which requires connecting the thyristor and the damping circuit and using high voltage for testing.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a low-voltage equivalent test device for the reverse recovery period protection function of a converter valve control unit, comprising a low-voltage module, a voltage divider unit, a main control unit, and a synchronous voltage acquisition unit. The low-voltage module is connected to the converter valve control unit under test through the voltage divider unit. The synchronous voltage acquisition unit is connected in parallel with the voltage divider unit. The converter valve control unit under test, the voltage divider unit, and the synchronous voltage acquisition unit are all connected to the main control unit.

[0008] Furthermore, the low-voltage module is a low-voltage transformer used to provide the sampling voltage and energy extraction voltage for the control unit of the converter valve under test.

[0009] Furthermore, the voltage divider unit includes a voltage divider resistor R1, a current-limiting resistor R2, a current-limiting resistor R3, and relays KM1, KM2, KM3, and KM4. The low-voltage module is connected to the Y terminal of the tested converter valve control unit via relay KM1 and voltage divider resistor R1. The low-voltage module is connected to the T terminal of the tested converter valve control unit via relay KM2 and current-limiting resistor R2. The low-voltage module is connected to the N terminal of the tested converter valve control unit via relay KM3. The main control unit is connected to the T terminal of the tested converter valve control unit via current-limiting resistor R3. The main control unit is connected to the N terminal of the tested converter valve control unit via relay KM4.

[0010] Furthermore, the main control unit is connected to the optical receiving interface, optical transmitting interface, and gate of the control unit of the converter valve under test, as well as relays KM1, KM2, KM3, and KM4.

[0011] Furthermore, the main control unit controls relays KM1 and KM3 to output 220V voltage to simulate the reverse recovery period impulse voltage by superimposing the input impulse voltage at the Y point, controls relays KM2 and KM3 to output 110V voltage to power the control unit of the converter valve under test, and controls relay KM4 to output 24V voltage to power the control unit of the converter valve under test during the reverse recovery period.

[0012] Furthermore, the synchronous voltage acquisition unit acquires the voltage across the voltage divider unit and sends the voltage information to the main control unit.

[0013] Furthermore, the main control unit detects the pulse width of the reverse recovery period protection gate signal through the IP back-check signal to determine whether a reverse recovery period protection action has occurred.

[0014] Furthermore, the test method for the low-pressure equivalent test device for the reverse recovery period protection function of the converter valve control unit includes the following steps:

[0015] Step 1: The main control unit supplies power to the TCU by controlling the closing of relays KM2 and KM3 and outputting voltage.

[0016] Step 2: The synchronous voltage acquisition unit acquires the voltage across the voltage divider unit as a complete sine wave voltage, and at the same time the main control unit sends a positive voltage establishment pulse to the control unit of the converter valve under test;

[0017] Step 3: The main control unit controls relays KM1 and KM3 to close and output 220V voltage to simulate the reverse recovery period impulse voltage by superimposing the input impulse voltage at point Y. It controls relay KM4 to close and output 24V voltage to power the control unit of the converter valve under test during the reverse recovery period. The control unit of the converter valve under test is triggered by the reverse recovery period protection under low voltage conditions.

[0018] Step 4: The control unit of the converter valve under test sends the reverse recovery period protection gate signal to the main control unit. The main control unit detects the pulse width of the reverse recovery period protection gate signal to determine whether the reverse recovery period protection action has occurred.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention provides a low-voltage equivalent test device for the reverse recovery period protection function of a converter valve control unit. Through a test circuit, the thyristor control unit is triggered normally. Within 700µs after the AC negative voltage drops below -15V, a relay controls the switching of the AC 220V voltage to simulate the reverse recovery period impulse voltage by superimposing an input impulse voltage at the Y point. The test circuit detects the pulse width of the reverse recovery period protection gate signal to determine whether the reverse recovery period protection has activated. This invention features a simple test circuit, allowing for testing of the reverse recovery period protection function of the converter valve thyristor control unit under low-voltage conditions. It eliminates the need for a high-voltage circuit and connections to the thyristor and damping circuit, enabling direct testing of the converter valve control unit. The simple testing method improves both safety and efficiency. Attached Figure Description

[0021] Figure 1 This is a structural block diagram of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0023] like Figure 1 As shown, a low-voltage equivalent test device for the reverse recovery period protection function of a converter valve control unit includes a low-voltage module 1, a voltage divider unit 2, a main control unit 3, and a synchronous voltage acquisition unit 4. The low-voltage module 1 is connected to the converter valve control unit TCU5 under test through the voltage divider unit 2. The synchronous voltage acquisition unit 4 is connected in parallel with the voltage divider unit 2. The converter valve control unit 5 under test, the voltage divider unit 2, and the synchronous voltage acquisition unit 4 are all connected to the main control unit 3.

[0024] Specifically, the low-voltage module 1 is a low-voltage transformer used to provide the sampling voltage and energy extraction voltage for the control unit of the converter valve under test.

[0025] The voltage divider unit 2 includes a voltage divider resistor R1, a current limiting resistor R2, a current limiting resistor R3, and relays KM1, KM2, KM3, and KM4. The low-voltage module is connected to the Y terminal of the tested converter valve control unit through relay KM1 and voltage divider resistor R1. The low-voltage module is connected to the T terminal of the tested converter valve control unit through relay KM2 and current limiting resistor R2. The low-voltage module is connected to the N terminal of the tested converter valve control unit through relay KM3. The main control unit is connected to the T terminal of the tested converter valve control unit through current limiting resistor R3. The main control unit is connected to the N terminal of the tested converter valve control unit through relay KM4.

[0026] The main control unit 3 is connected to the optical receiving interface, optical transmitting interface, and gate of the control unit 5 of the converter valve under test, as well as relays KM1, KM2, KM3, and KM4.

[0027] The main control unit 3 controls relays KM1 and KM3 to output 220V voltage to simulate the reverse recovery period impulse voltage by superimposing the input impulse voltage at the Y point. It controls relays KM2 and KM3 to output 110V voltage to power the control unit of the converter valve under test. It controls relay KM4 to output 24V voltage to power the control unit of the converter valve under test during the reverse recovery period.

[0028] The synchronous voltage acquisition unit 4 acquires the voltage across the voltage divider unit 2 and sends the voltage information to the main control unit 3.

[0029] The main control unit 3 detects the pulse width of the reverse recovery period protection gate signal through the IP back-check signal to determine whether a reverse recovery period protection action has occurred.

[0030] The testing method of the low-pressure equivalent test device for the reverse recovery period protection function of the converter valve control unit in this embodiment of the invention includes the following steps:

[0031] Step 1: The main control unit supplies power to the TCU by controlling the closing of relays KM2 and KM3 and outputting voltage.

[0032] Step 2: The synchronous voltage acquisition unit acquires the voltage across the voltage divider unit as a complete sine wave voltage, and at the same time the main control unit sends a positive voltage establishment pulse to the TCU;

[0033] Step 3: The main control unit controls relays KM1 and KM3 to close and output 220V voltage to simulate the reverse recovery period impulse voltage by superimposing the input impulse voltage at point Y. It controls relay KM4 to close and output 24V voltage to power the TCU during the reverse recovery period. The TCU triggers the reverse recovery period protection under low voltage conditions.

[0034] Step 4: The TCU sends the reverse recovery period protection gate signal to the main control unit. The main control unit detects the pulse width of the reverse recovery period protection gate signal to determine whether a reverse recovery period protection action has occurred.

[0035] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-pressure equivalent test device for the reverse recovery period protection function of a converter valve control unit, characterized in that: It includes a low-voltage module, a voltage divider unit, a main control unit, and a synchronous voltage acquisition unit. The low-voltage module is connected to the control unit of the converter valve under test through the voltage divider unit. The synchronous voltage acquisition unit is connected in parallel with the voltage divider unit. The control unit of the converter valve under test, the voltage divider unit, and the synchronous voltage acquisition unit are all connected to the main control unit. The voltage divider unit includes a voltage divider resistor R1, a current limiting resistor R2, a current limiting resistor R3, and relays KM1, KM2, KM3, and KM4. The low-voltage module is connected to the Y terminal of the tested converter valve control unit via relay KM1 and voltage divider resistor R1. The low-voltage module is connected to the T terminal of the tested converter valve control unit via relay KM2 and current limiting resistor R2. The low-voltage module is connected to the N terminal of the tested converter valve control unit via relay KM3. The main control unit is connected to the T terminal of the tested converter valve control unit via current limiting resistor R3. The main control unit is connected to the N terminal of the tested converter valve control unit via relay KM4. The main control unit controls relays KM1 and KM3 to output 220V voltage to simulate the reverse recovery period impulse voltage by superimposing the input impulse voltage at the Y point. It controls relays KM2 and KM3 to output 110V voltage to power the control unit of the converter valve under test. It controls relay KM4 to output 24V voltage to power the control unit of the converter valve under test during the reverse recovery period. Within 700µs after the negative AC voltage drops below -15V, the AC220V voltage is switched via relay control to simulate the reverse recovery period impulse voltage by superimposing the input impulse voltage at the Y point.

2. The low-pressure equivalent test device for the reverse recovery period protection function of the converter valve control unit according to claim 1, characterized in that: The low-voltage module is a low-voltage transformer used to provide the sampling voltage and energy extraction voltage for the control unit of the converter valve under test.

3. The low-pressure equivalent test device for the reverse recovery period protection function of the converter valve control unit according to claim 2, characterized in that: The main control unit is connected to the optical receiving interface, optical transmitting interface, and gate of the control unit of the converter valve under test, as well as relays KM1, KM2, KM3, and KM4.

4. The low-pressure equivalent test device for the reverse recovery period protection function of the converter valve control unit according to claim 3, characterized in that: The synchronous voltage acquisition unit acquires the voltage across the voltage divider unit and sends the voltage information to the main control unit.

5. The low-pressure equivalent test device for the reverse recovery period protection function of the converter valve control unit according to claim 4, characterized in that: The main control unit detects the pulse width of the reverse recovery period protection gate signal through the IP back-check signal to determine whether a reverse recovery period protection action has occurred.

6. A test method for the low-pressure equivalent test device for the reverse recovery period protection function of the converter valve control unit according to claim 5, characterized in that, Includes the following steps: Step 1: The main control unit supplies power to the TCU by controlling the closing of relays KM2 and KM3 and outputting voltage. Step 2: The synchronous voltage acquisition unit acquires the voltage across the voltage divider unit as a complete sine wave voltage, and at the same time the main control unit sends a positive voltage establishment pulse to the control unit of the converter valve under test; Step 3: The main control unit controls relays KM1 and KM3 to close and output 220V voltage, which is then superimposed with the input impulse voltage at point Y to simulate the reverse recovery period impulse voltage. Relay KM4 is controlled to close and output 24V voltage to power the tested converter valve control unit during the reverse recovery period. The tested converter valve control unit triggers reverse recovery period protection under low voltage conditions. Within 700µs after the AC voltage negative direction drops below -15V, the relay controls the switching of AC 220V voltage to superimpose the input impulse voltage at point Y to simulate the reverse recovery period impulse voltage. Step 4: The control unit of the converter valve under test sends the reverse recovery period protection gate signal to the main control unit. The main control unit detects the pulse width of the reverse recovery period protection gate signal to determine whether the reverse recovery period protection action has occurred.

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