Test system for power cells in a converter valve

Abstract

The application relates to a test system of power units in a converter valve, the converter valve comprising a first bridge arm and a second bridge arm connected in series, the first bridge arm and the second bridge arm each comprising a plurality of power units connected in series; the test system comprising a load connected at both ends of the first bridge arm and a test module connected to each power unit in the second bridge arm, the test module being configured to control each power unit in the second bridge arm to perform a switching action while each power unit in the first bridge arm remains off, and collect electrical parameters of each power unit in the second bridge arm, each electrical parameter being used to determine a test result. Through the technical scheme provided by the application, the technical problem that the existing test scheme is difficult to simulate the working condition of the power unit under real working conditions and the test result is inaccurate is solved.

Description

Technical Field

[0001] This application relates to the field of power electronics testing technology, and in particular to a testing system for power units in a converter valve. Background Technology

[0002] With the construction of the global energy internet, high-voltage direct current (HVDC) transmission technology has been widely applied, especially flexible DC transmission technology based on voltage source converters (VSCs). Due to its flexibility and controllability, it has become a core component of modern smart grids. In VSC-HVDC power systems, the converter valve is the core device for realizing AC-DC power conversion. To withstand DC voltages of up to hundreds of kilovolts, converter valves typically use multiple power units connected in series.

[0003] These power units require rigorous testing before being put into operation. Existing testing methods mainly focus on single-pulse or continuous-pulse testing of individual power units. However, for converter valves composed of multiple power units connected in series, the different power units will affect each other, making it difficult for existing testing methods to simulate the actual working conditions of the power units, resulting in inaccurate test results. Summary of the Invention

[0004] Therefore, it is necessary to provide a testing system for the power unit in the converter valve, which aims to solve the technical problem that the existing testing schemes are difficult to simulate the working conditions of the power unit under real working conditions and have inaccurate test results.

[0005] A test system for power units in a converter valve, wherein the converter valve includes a first bridge arm and a second bridge arm connected in series, and both the first bridge arm and the second bridge arm include multiple power units connected in series.

[0006] The testing system includes:

[0007] A load, the load being used to connect to both ends of the first bridge arm;

[0008] A test module, wherein the test module is used to connect to each of the power units in the second bridge arm; wherein the test module is configured to:

[0009] While each power unit in the first bridge arm remains off, each power unit in the second bridge arm is controlled to perform a switching action, and the electrical parameters of each power unit in the second bridge arm are collected. Each electrical parameter is used to determine the test result.

[0010] In one embodiment, the test module is configured as follows:

[0011] A control signal is synchronously sent to each of the power units in the second bridge arm to control each of the power units in the second bridge arm to perform switching operations; wherein, the control signal is used to control each of the power units in the second bridge arm to turn on for a first preset time and then turn off for a second preset time, and then turn on for a third preset time after turning off for the second preset time.

[0012] In one embodiment, the control signal includes a first turn-on pulse and a second turn-on pulse, wherein the effective pulse width of the first turn-on pulse is a first preset duration, and the effective pulse width of the second turn-on pulse is a third preset duration, and the test module is configured to:

[0013] The first activation pulse is synchronously sent to each of the power units in the second bridge arm, and after the second preset time after the first activation pulse ends, the second activation pulse is synchronously sent to each of the power units in the second bridge arm.

[0014] In one embodiment, both the first preset duration and the third preset duration are greater than the preset on-state duration; wherein, the on-state duration is the minimum duration from the turn-off to the steady-state turn-on of each power unit in the second bridge arm.

[0015] In one embodiment, the second preset duration is greater than the preset off-state duration; wherein the off-state duration is the minimum duration from turn-on to steady-state off for each power unit in the second bridge arm.

[0016] In one embodiment, the electrical parameters of each power unit in the second bridge arm include off-state electrical parameters and on-state electrical parameters, and the test module is configured to:

[0017] The shutdown electrical parameters of each power unit in the second bridge arm are collected, and each shutdown electrical parameter is used to determine the shutdown consistency of each power unit in the second bridge arm; wherein, the shutdown electrical parameters are the electrical parameters of each power unit in the second bridge arm within the second preset time period;

[0018] The power-on electrical parameters of each power unit in the second bridge arm are collected, and each power-on electrical parameter is used to determine the power-on consistency of each power unit in the second bridge arm; wherein, the power-on electrical parameters are the electrical parameters of each power unit in the second bridge arm within the third preset time period.

[0019] In one embodiment, the test system further includes a DC voltage source, a first switching unit, and an energy storage unit. The first end of the DC voltage source is connected to the first end of the first switching unit. The second end of the first switching unit is connected to the first end of the first bridge arm and the first end of the energy storage unit. The second end of the first bridge arm is connected to the first end of the second bridge arm. The second end of the DC voltage source is connected to the second end of the second bridge arm and the second end of the energy storage unit.

[0020] In one embodiment, the power unit includes a fully controlled switching device and an anti-parallel diode, the cathode of which is connected to the current input terminal of the fully controlled switching device, the anode of which is connected to the current output terminal of the fully controlled switching device, and the control terminal of the fully controlled switching device is connected to the test module.

[0021] In one embodiment, the power unit further includes an absorption circuit, the first end of which is connected to the cathode of the anti-parallel diode and the current input terminal of the fully controlled switching device, and the second end of which is connected to the anode of the anti-parallel diode and the current output terminal of the fully controlled switching device.

[0022] In one embodiment, the absorption circuit includes a clamping diode, an absorption capacitor, and an absorption resistor. The anode of the clamping diode is connected to the cathode of the anti-parallel diode and the current input terminal of the fully controlled switching device, respectively. The cathode of the clamping diode is connected to the first terminal of the absorption capacitor and the first terminal of the absorption resistor, respectively. The second terminal of the absorption capacitor is connected to the anode of the anti-parallel diode, the current output terminal of the fully controlled switching device, and the second terminal of the absorption resistor, respectively.

[0023] The aforementioned test system for the power units in the converter valve includes a first bridge arm and a second bridge arm connected in series, each of which comprises multiple power units connected in series. The test system includes a load and a test module. The load is connected to both ends of the first bridge arm, and the test module is connected to each power unit in the second bridge arm. The test module is configured to control the switching action of each power unit in the second bridge arm while keeping all power units in the first bridge arm off, and to collect the electrical parameters of each power unit in the second bridge arm. These electrical parameters are used to determine the test results.

[0024] Since both the first and second bridge arms consist of multiple power units connected in series, and the power units in the first bridge arm remain off during testing to form a freewheeling loop, the test system performs tests on these power units. During the test, the actual operating conditions of the converter valve when multiple power units are connected in series in practical applications are simulated, achieving a complete simulation of the converter valve's commutation process. The test system then collects the electrical parameters of each power unit in the second bridge arm. The test results obtained through comprehensive comparison and analysis of these electrical parameters can effectively reflect the mutual influence of the power units when used in series, thus yielding more accurate test results. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the test system for the power unit in a converter valve in one embodiment;

[0027] Figure 2 This is a schematic diagram of the power unit in a converter valve in one embodiment;

[0028] Figure 3 This is a schematic diagram of the voltage waveform of the control signal in one embodiment;

[0029] Figure 4 This is an equivalent circuit diagram of the circuit formed by the first bridge arm and the second bridge arm during the first test phase in one embodiment;

[0030] Figure 5 This is an equivalent circuit diagram of the circuit formed by the first bridge arm and the second bridge arm during the second test phase in one embodiment;

[0031] Figure 6 This is an equivalent circuit diagram of the circuit formed by the first bridge arm and the second bridge arm during the third test phase in one embodiment;

[0032] Figure 7 This is a voltage waveform diagram of each power unit in the second bridge arm within a second preset time period in one embodiment;

[0033] Figure 8 This is a current waveform diagram of each power unit in the second bridge arm within a third preset time period in one embodiment;

[0034] Figure 9This is a schematic diagram of the test system for the power unit in the converter valve in another embodiment;

[0035] Figure 10 This is a schematic diagram of the test process of a test system based on the power unit in a converter valve in one embodiment.

[0036] Explanation of reference numerals in the attached figures:

[0037] 100. Converter valve; 110. First bridge arm; 120. Second bridge arm; 130. Power unit; 131. Absorption circuit; 200. Load; 300. Test module; 400. DC voltage source; 500. First switching unit; 600. Energy storage unit; 700. Second switching unit; 800. Discharge unit;

[0038] T, Fully controlled switching device; D0, Anti-parallel diode; Ds, Clamping diode; Rs, Absorption resistor; Cs, Absorption capacitor; L0, Load inductor; L1, First stray inductor; L2, Second stray inductor; L3, Third stray inductor. Detailed Implementation

[0039] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0042] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0043] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0044] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0045] This application discloses a test system for power units in a converter valve. This test system is mainly used in the testing scenario of converter valves composed of series power units in the field of high voltage direct current transmission.

[0046] Reference Figure 1 The test system for the power units in the converter valve 100 tests the power units 130 in the converter valve 100. The converter valve 100 includes a first bridge arm 110 and a second bridge arm 120 connected in series. Both the first bridge arm 110 and the second bridge arm 120 include multiple power units 130 connected in series. For example, the first bridge arm 110 includes n power units 130, denoted as Hh1, Hh2, ..., Hhn, where n is an integer greater than or equal to 2. The second bridge arm 120 includes m power units 130, denoted as Hl1, Hl2, ..., Hlm, where m is an integer greater than or equal to 2. n and m can be the same or different.

[0047] The test system includes a load 200 and a test module 300. The load 200 is used to connect to both ends of the first bridge arm 110, and the test module 300 is used to connect to each power unit 130 in the second bridge arm 120.

[0048] The test module 300 is configured to control each power unit 130 in the second bridge arm 120 to perform switching actions while keeping each power unit 130 in the first bridge arm 110 off, and to collect the electrical parameters of each power unit 130 in the second bridge arm 120. The electrical parameters are used to determine the test results.

[0049] Specifically, load 200 is connected to both ends of the first bridge arm 110 in parallel. Load 200 is used to simulate inductive load characteristics during testing, generating inductive reactive power to simulate the operating conditions of the converter valve 100. In some feasible embodiments, load 200 is an inductor with a large inductance value, used to generate inductive reactive power during the testing of the first bridge arm 110 and the second bridge arm 120. The first end of the inductor is connected to the first end of the first bridge arm 110, and the second end of the inductor is connected to the second end of the second bridge arm 120, with the second end of the first bridge arm 110 connected to the first end of the second bridge arm 120. In some feasible embodiments, the inductance value of the inductor can be set by those skilled in the art according to actual testing requirements. By adjusting the inductance value, the magnitude of the inductive current generated in load 200 can be changed, thereby simulating the inductive current situation of the converter valve 100 under different operating conditions.

[0050] The test module 300 is connected to each power unit 130 in the second bridge arm 120. During testing, the test module 300 can drive each power unit 130 in the second bridge arm 120 to perform switching actions and can collect the electrical parameters of each power unit 130 in the second bridge arm 120 during the switching process. As an example, the test module 300 can be connected to the drive stage of each power unit 130 in the second bridge arm 120 via a synchronization signal line or optical fiber, and drives each power unit 130 in the second bridge arm 120 to perform switching actions during testing by sending control signals to each power unit 130 in the second bridge arm 120.

[0051] In some feasible embodiments, the electrical parameters of each power unit 130 in the second bridge arm 120 may include voltage change parameters and current change parameters of each power unit 130 in the second bridge arm 120. As an example, the test module 300 includes a data acquisition unit, a drive unit, multiple voltage sensors, and multiple current sensors. The multiple voltage sensors are connected in parallel with the multiple power units 130 to acquire voltage change parameters of each power unit 130 in the second bridge arm 120 during switching operations. The multiple current sensors are connected in series with the multiple power units 130 to acquire current change parameters of each power unit 130 in the second bridge arm 120 during switching operations. The data acquisition unit is connected to both the multiple voltage sensors and the multiple current sensors to receive the voltage change parameters of each power unit 130 in the second bridge arm 120 during switching operations acquired by the multiple voltage sensors, and to receive the current change parameters of each power unit 130 in the second bridge arm 120 during switching operations acquired by the multiple current sensors.

[0052] As an example, the test module 300 generates a voltage waveform diagram after collecting voltage change parameters and a current waveform diagram after collecting current change parameters, thereby clearly representing the electrical parameters of each power unit 130 in the second bridge arm 120 during the switching operation. It can clearly show the changes in electrical parameters of each power unit 130 in the second bridge arm 120 during the switching operation.

[0053] In some feasible embodiments, refer to Figure 2 The power unit 130 includes a fully controlled switching device T and an anti-parallel diode D0. The cathode of the anti-parallel diode D0 is connected to the current input terminal of the fully controlled switching device T, and the anode of the anti-parallel diode D0 is connected to the current output terminal of the fully controlled switching device T. The control terminal of the fully controlled switching device T is connected to the test module 300.

[0054] Specifically, power unit 130 includes a fully controllable switching device T and an anti-parallel diode D0. The fully controllable switching device T refers to a power electronic device that can be simultaneously controlled to turn on and off via a control signal. Examples of fully controllable switching devices T include insulated-gate bipolar transistors (IGBTs), integrated gate commutated thyristors (IGCTs), and metal-oxide-semiconductor field-effect transistors (MOSFETs), but it is not limited to these. The current input terminal of the fully controllable switching device T is connected to the cathode of the anti-parallel diode D0. The current input terminal of the fully controllable switching device T is the current input terminal when the fully controllable switching device T is turned on. For example, for a fully controllable switching device T of an insulated-gate bipolar transistor, the current input terminal of the fully controllable switching device T is the collector of the insulated-gate bipolar transistor. The current output terminal of the fully controlled switching device T is connected to the anode of the anti-parallel diode D0. The current output terminal of the fully controlled switching device T is the current output terminal when it is turned on. For example, for a fully controlled switching device T with an integrated gate commutated thyristor, the current output terminal of the fully controlled switching device T is the cathode of the integrated gate commutated thyristor. The control terminal of the fully controlled switching device T is connected to the test module 300. The control terminal of the fully controlled switching device T serves as the driving terminal of the power unit 130, used to control the switching action of the fully controlled switching device T based on the received control signal, thereby controlling the switching action of the power unit 130.

[0055] In some feasible embodiments, the power unit 130 further includes an absorption circuit 131, the first end of which is connected to the cathode of the anti-parallel diode D0 and the current input terminal of the fully controlled switching device T, and the second end of which is connected to the anode of the anti-parallel diode D0 and the current output terminal of the fully controlled switching device T.

[0056] Specifically, the absorption circuit 131 is used to suppress voltage spikes and current changes during the switching process of the power unit 130, limiting the operating trajectory of the fully controlled switching device T in the power unit 130 to within a safe operating area. Especially in a series structure, due to the inevitable differences in the switching speeds of the fully controlled switching devices T in each power unit 130, the fully controlled switching devices T in the power unit 130 that are turned off first often experience significant voltage overshoot. The absorption circuit 131 can smooth out such voltage overshoots by temporarily storing energy, thereby achieving dynamic voltage equalization.

[0057] In some feasible embodiments, the absorption circuit 131 includes a clamping diode Ds, an absorption capacitor Cs, and an absorption resistor Rs. The anode of the clamping diode Ds is connected to the cathode of the anti-parallel diode D0 and the current input terminal of the fully controlled switching device T, respectively. The cathode of the clamping diode Ds is connected to the first terminal of the absorption capacitor Cs and the first terminal of the absorption resistor Rs, respectively. The second terminal of the absorption capacitor Cs is connected to the anode of the anti-parallel diode D0, the current output terminal of the fully controlled switching device T, and the second terminal of the absorption resistor Rs, respectively.

[0058] Specifically, when the fully controlled switching device T in the power unit 130 is turned off, voltage overshoot is likely to occur. At this time, the clamping diode Ds turns on, storing the high-voltage energy of the voltage overshoot in the absorption capacitor Cs, thereby preventing the high-voltage energy from breaking down the fully controlled switching device T in the power unit 130. Subsequently, the high-voltage energy is released through the absorption resistor Rs.

[0059] Based on the structure of the power unit 130 described in the above embodiments, in some feasible embodiments, the test module 300 is also connected to each power unit 130 in the first bridge arm 110. During the test, the test module 300 controls the fully controlled switching devices of each power unit 130 in the first bridge arm 110 to remain off, thereby controlling each power unit 130 in the first bridge arm 110 to remain off. Simultaneously, the test module 300 controls the fully controlled switching devices of each power unit 130 in the second bridge arm 120 to perform switching actions, thereby controlling each power unit 130 in the second bridge arm 120 to perform switching actions. The test module 300 collects the electrical parameters of each power unit 130 in the second bridge arm 120, specifically the electrical parameters of the fully controlled switching devices of each power unit 130 in the second bridge arm 120.

[0060] The testing principle of the test system for the power unit 130 in the converter valve 100 provided in this application is described in conjunction with the above embodiments. During the test, after the test system is powered on, since each power unit 130 in the first bridge arm 110 remains off, when each power unit 130 in the second bridge arm 120 is turned on, the current flows from the power supply through the second bridge arm 120 and the load 200, and returns to the power supply. When the power unit 130 in the second bridge arm 120 is turned off, since the load 200 is an inductive load 200, the current on it cannot change abruptly, and the current needs to find a freewheeling path. At this time, the anti-parallel diodes D0 of each power module in the first bridge arm 110, which remain off, are forced to turn on, forming a freewheeling circuit.

[0061] During the aforementioned test, the test module 300 collects the electrical parameters of each power unit 130 in the second bridge arm 120 to obtain the test results. As an example, the test results may include the turn-on consistency and turn-off consistency of each power unit 130 in the second bridge arm 120.

[0062] Understandably, the above test simulated the switching condition of the inductive load 200 in the actual operation of the converter valve 100, so that the power unit 130 of the second bridge arm 120 bears all the voltage and current from the power supply at the moment of turn-off. At this time, the obtained electrical parameters reflect the mutual influence of multiple power units 130 when they are used in series. The test results obtained based on these electrical parameters truly reflect the working conditions of the multiple power units 130 connected in series in the converter valve 100 under actual operating conditions.

[0063] Based on the above embodiments, the testing process simulates the actual operating conditions of the converter valve 100 when multiple power units 130 are connected in series in practical applications, and achieves a complete simulation of the commutation process of the converter valve 100. The testing system then collects the electrical parameters of each power unit 130 in the second bridge arm 120. The test results obtained through comprehensive comparison and analysis of these electrical parameters can better reflect the mutual influence of each power unit 130 when used in series, thus obtaining more accurate test results.

[0064] In some feasible embodiments, the test module 300 is configured as follows:

[0065] Control signals are synchronously sent to each power unit 130 in the second bridge arm 120 to control each power unit 130 in the second bridge arm 120 to perform switching operations.

[0066] The control signal is used to control each power unit 130 in the second bridge arm 120 to turn on for a first preset duration, then turn off for a second preset duration, and then turn on for a third preset duration.

[0067] Specifically, the test module 300 controls each power unit 130 in the second bridge arm 120 to remain off when the test system is not powered on. After the test system is powered on, the test module 300 synchronously sends control signals to each power unit 130 in the second bridge arm 120, first controlling each power unit 130 in the second bridge arm 120 to be turned on for a first preset duration, then controlling each power unit 130 in the second bridge arm 120 to be turned off for a second preset duration, and finally controlling each power unit 130 in the second bridge arm 120 to be turned on for a third preset duration, ultimately controlling each power unit 130 in the second bridge arm 120 to be turned off. As an example, the test module 300 sends control signals to the control electrode of the fully controllable switching device T of each power unit 130 in the second bridge arm 120.

[0068] In the above embodiment, each power unit 130 in the second bridge arm 120 is controlled to turn on first, then turn off, and then turn on again. The actual commutation process of the converter valve 100 composed of series power units 130 is simulated. Based on this, the electrical parameters collected reflect the mutual influence of each power unit 130 when used in series, and the test results obtained are true and valid.

[0069] In some feasible embodiments, the control signal includes a first turn-on pulse and a second turn-on pulse, the effective pulse width of the first turn-on pulse is a first preset duration, the effective pulse width of the second turn-on pulse is a third preset duration, and the test module 300 is configured as follows:

[0070] The first activation pulse is synchronously sent to each power unit 130 in the second bridge arm 120. After a second preset time after the first activation pulse ends, the second activation pulse is synchronously sent to each power unit 130 in the second bridge arm 120.

[0071] Specifically, refer to Figure 3The control signal Tr includes a first turn-on pulse Tr1 and a second turn-on pulse Tr2, both of which are square waves. The effective pulse width of the first turn-on pulse Tr1 is a first preset duration t1, and the effective pulse width of the second turn-on pulse Tr2 is a third preset duration t3. When the first turn-on pulse Tr1 is sent to each power unit 130 in the second bridge arm 120, each power unit 130 in the second bridge arm 120 turns on at the rising edge of the first turn-on pulse Tr1 and continues for the first preset duration t1. Each power unit 130 in the second bridge arm 120 turns off at the falling edge of the first turn-on pulse Tr1. The second turn-on pulse Tr2 is sent to each power unit 130 in the second bridge arm 120 for a second preset duration t2 after the first turn-on pulse Tr1 has finished being sent, so that each power unit 130 in the second bridge arm 120 remains off for the second preset duration t2. After a second preset duration t2, the second turn-on pulse Tr2 is sent to each power unit 130 in the second bridge arm 120. Each power unit 130 in the second bridge arm 120 turns on at the rising edge of the second turn-on pulse Tr2 and continues for a third preset duration t3. Each power unit 130 in the second bridge arm 120 turns off at the falling edge of the second turn-on pulse Tr2.

[0072] As an example, the test module 300 synchronously sends a first turn-on pulse Tr1 to the fully controlled switching device T in each power unit 130 of the second bridge arm 120. After a second preset time t2 after the first turn-on pulse Tr1 ends, the test module 300 synchronously sends a second turn-on pulse Tr2 to the fully controlled switching device T in each power unit 130 of the second bridge arm 120.

[0073] In this embodiment, the control signal Tr is configured as a first turn-on pulse Tr1 and a second turn-on pulse Tr2, and the transmission interval between the first turn-on pulse Tr1 and the second turn-on pulse Tr2 is configured. This achieves control of the switching states of each power unit 130 in the second bridge arm 120 in a relatively simple manner, simulating the actual commutation process of the converter valve 100.

[0074] In some feasible embodiments, both the first preset duration and the third preset duration are greater than the preset on-state duration.

[0075] The on-state duration is the shortest duration from the turn-off to the steady-state turn-on of each power unit 130 in the second bridge arm 120.

[0076] Specifically, the test module 300 pre-stores the minimum duration from off to steady-state on for each power unit 130 in the second bridge arm 120, i.e., pre-stores the on-state duration. This on-state duration can be obtained by those skilled in the art from the datasheets of each power unit 130 in the second bridge arm 120. As an example, the on-state duration is the minimum duration from off to steady-state on for the fully controlled switching device T in each power unit 130 of the second bridge arm 120. The test module 300 configures the first turn-on pulse and the second turn-on pulse based on the on-state duration, such that both the first preset duration and the third preset duration are greater than the preset on-state duration.

[0077] In this embodiment, because the fully controlled switching device T in the power unit 130 has not yet reached equilibrium in its internal carrier distribution during the initial turn-on stage, the turn-on voltage drop is high and unstable. Therefore, it is necessary to ensure that the turn-on time exceeds its minimum turn-on time, that is, the first preset duration and the third preset duration need to be greater than the on-state duration. Through this embodiment, by configuring the first turn-on pulse and the second turn-on pulse, each power unit 130 in the second bridge arm 120 is turned on in a steady state under the action of the first turn-on pulse and the second turn-on pulse, ensuring that the obtained electrical parameters are true and valid, thereby ensuring the accuracy of the test results.

[0078] In some feasible embodiments, the second preset duration is longer than the preset off-state duration.

[0079] The off-state duration is the shortest duration from turn-on to steady-state turn-off for each power unit 130 in the second bridge arm 120.

[0080] Specifically, the test module 300 pre-stores the minimum duration from turn-on to steady-state turn-off for each power unit 130 in the second bridge arm 120, i.e., pre-stores the off-state duration. This off-state duration can be obtained by those skilled in the art from the datasheets of each power unit 130 in the second bridge arm 120. As an example, the on-state duration is the minimum duration from turn-on to steady-state turn-off for the fully controlled switching device T in each power unit 130 of the second bridge arm 120. The test module 300 configures the transmission time interval between the first turn-on pulse and the second turn-on pulse based on the off-state duration, i.e., it configures a second preset duration, such that the second preset duration is longer than the preset off-state duration.

[0081] In this embodiment, the fully controlled switching device T in the power unit 130 requires a certain amount of time to recover its blocking capability after being turned off. If the time interval between re-turning on (the second preset duration) is less than the minimum turn-off time of the fully controlled switching device T, i.e., less than the off-state duration, the fully controlled switching device T may be subjected to high voltage again before it has fully recovered its blocking capability, leading to device damage. By configuring the second preset duration to be longer than the preset off-state duration, the safety of the power unit 130 during testing is ensured.

[0082] In conjunction with the above embodiments, and referring to Figure 4 , 5 Section 6 describes the testing principle of the testing system provided in the embodiments of this application. It is understood that... Figure 4 , 5 In section 6, both the first bridge arm 110 and the second bridge arm 120 include only one power unit 130, which uses an integrated gate commutated thyristor as the fully controlled device. Figure 4 , 5 The circuit in section 6 is consistent with the circuit in section 6, which includes multiple series power units 130 in both the first bridge arm 110 and the second bridge arm 120, in terms of commutation principle and testing principle.

[0083] The stray inductance on the main circuit of the first bridge arm 110 and the second bridge arm 120 is represented as the first stray inductor L1, the stray inductance in the absorption circuit 131 in the second bridge arm 120 is represented as the second stray inductor L2, the stray inductance in the absorption circuit 131 in the first bridge arm 110 is represented as the third stray inductor L3, and the load 200 connected in parallel across the first bridge arm 110 is the load inductor L0.

[0084] The testing process of the testing system provided in this application mainly includes the following three stages.

[0085] First testing phase: Reference Figure 4 In the second bridge arm 120, each power unit 130 is synchronously turned on under the action of the first turn-on pulse, and this continues for a first preset duration. At this time, the voltage of the power supply of the test system is fully applied across the load inductor L0, and the load 200 in the current circuit is an inductive load 200. According to the characteristics of the inductive load 200, the current of the load 200 will increase linearly. The purpose of this stage is to establish the target current value required for the test in the load 200. The length of the first preset duration determines the current magnitude of each power unit 130 in the second bridge arm 120 at the turn-off moment after the first preset duration, and is usually set according to the rated current or overload current requirement of the fully controlled switching device T in each power unit 130 in the second bridge arm 120. By controlling the first preset duration, the turn-off characteristics of the fully controlled switching device T in each power unit 130 in the second bridge arm 120 can be tested at any current level.

[0086] Second testing phase: Reference Figure 5Upon the end of the first turn-on pulse, all power units 130 in the second bridge arm 120 are simultaneously turned off, entering the second preset duration. When all controlled devices in each power unit 130 of the second bridge arm 120 are turned off, the load 200 current needs to find a new path. The load 200 current will be transferred from the second bridge arm 120 to the anti-parallel diodes D0 in each power unit 130 of the first bridge arm 110. Correspondingly, the clamping diode Ds in the absorption circuit 131 of the power unit 130 on the second bridge arm 120 is turned on, causing the absorption capacitor Cs in the absorption circuit 131 of the power unit 130 on the second bridge arm 120 to absorb a portion of the electrical energy. At this time, the test module 300 collects the electrical parameters of each power unit 130 in the second bridge arm 120 and analyzes the voltage distribution of each power unit 130 in the second bridge arm 120 at the turn-off time. If the peak voltage of a certain power unit 130 in the second bridge arm 120 is significantly higher than that of other power units 130, it indicates that the turn-off speed of the power unit 130 is too fast or the parameters of the absorption circuit 131 are mismatched.

[0087] Third testing phase: Reference Figure 6 After a certain period following the second preset time, the clamping diode Ds turns off because the absorption capacitor Cs absorbs some electrical energy. At this time, all power units 130 in the second bridge arm 120 remain off and the clamping diode Ds is also off. The load current 200 will freewheel through the anti-parallel diodes D0 of each power module in the first bridge arm 110. The commutation process is completed.

[0088] In some feasible embodiments, the electrical parameters of each power unit 130 in the second bridge arm 120 include turn-off electrical parameters and turn-on electrical parameters, and the test module 300 is configured as follows:

[0089] The shutdown electrical parameters of each power unit 130 in the second bridge arm 120 are collected, and each shutdown electrical parameter is used to determine the shutdown consistency of each power unit 130 in the second bridge arm 120.

[0090] Among them, the shutdown electrical parameters are the electrical parameters of each power unit 130 in the second bridge arm 120 within the second preset time period.

[0091] The power-on electrical parameters of each power unit 130 in the second bridge arm 120 are collected, and each power-on electrical parameter is used to determine the power-on consistency of each power unit 130 in the second bridge arm 120.

[0092] The electrical parameters for activation are the electrical parameters of each power unit 130 in the second bridge arm 120 within the third preset time period.

[0093] Specifically, the shutdown electrical parameters are the electrical parameters of each power unit 130 in the second bridge arm 120 within the second preset time period. As an example, the shutdown electrical parameters can be the current input-current output voltage value of the fully controlled switching device T in each power unit 130 in the second bridge arm 120. For example, if the fully controlled switching device T in each power unit 130 in the second bridge arm 120 is an insulated gate bipolar transistor, then the shutdown electrical parameters are the collector-emitter voltage of the insulated gate bipolar transistor.

[0094] In some feasible embodiments, the test module 300 generates voltage waveforms of each power unit 130 in the second bridge arm 120 within a second preset time period based on the shutdown electrical parameters, and determines the shutdown consistency of each power unit 130 in the second bridge arm 120 based on the analysis of the voltage waveforms. The voltage waveforms are specifically as follows... Figure 7 As shown.

[0095] exist Figure 7 In the second bridge arm 120, Ut represents the voltage value between the current input and current output terminals of the fully controlled switching device T in each power unit 130. Figure 7 There are two voltage spike amplitudes, namely Udsp and Udm. Udsp is the first turn-off spike voltage of the power unit 130 in the second bridge arm 120 caused by the stray inductance in the series structure of the first bridge arm 110 and the second bridge arm 120. Udm is the second turn-off spike voltage of the power unit 130 in the second bridge arm 120 caused by the absorption capacitor Cs in the absorption circuit 131 of the power unit 130 in the second bridge arm 120. The test module 300 compares the first turn-off spike voltage and the second turn-off spike voltage of each power unit 130 in the second bridge arm 120 to determine the turn-off consistency of each power unit 130 in the second bridge arm 120. For example, the second bridge arm 120 includes 10 power units 130. If the first turn-off peak voltage of one of the power units 130 is significantly greater than the first turn-off peak voltage of the other power units 130, it indicates that the turn-off characteristics of the power unit 130 are different from those of the other power units 130, and the turn-off consistency of the power units 130 in the second bridge arm 120 is poor.

[0096] Furthermore, since the second turn-off voltage spike is caused by the absorption capacitor Cs in the absorption circuit 131 of the power unit 130 in the second bridge arm 120, the test module 300 can determine the design parameters of the absorption capacitor Cs and the absorption resistor Rs in the absorption circuit 131 based on the second turn-off voltage spike.

[0097] The turn-on electrical parameters are the electrical parameters of each power unit 130 in the second bridge arm 120 within the third preset time period. As an example, the turn-on electrical parameters can be the current value of the current input terminal to the current output terminal of the fully controlled switching device T in each power unit 130 in the second bridge arm 120. For example, if the fully controlled switching device T in each power unit 130 in the second bridge arm 120 is an insulated gate bipolar transistor, then the turn-on electrical parameters are the collector-emitter current of the insulated gate bipolar transistor.

[0098] In some feasible embodiments, the test module 300 generates current waveforms of each power unit 130 in the second bridge arm 120 within a third preset time period based on the turn-on electrical parameters, and determines the turn-on consistency of each power unit 130 in the second bridge arm 120 based on the analysis of the current waveforms. The specific current waveforms are as follows... Figure 8 As shown, It represents the current input-output current value of the fully controlled switching device T in each power unit 130 of the second bridge arm 120. As an example, the test module 300 can determine the rate of change of the current input-output current value of each power unit 130 in the second bridge arm 120 based on the current waveform diagram of each power unit 130, and verify the turn-on consistency of each power unit 130 based on the comparison results of the rate of change of the current input-output current value.

[0099] In this embodiment, the turn-off consistency of each power unit 130 in the second bridge arm 120 can be verified based on the turn-off electrical parameters, and the turn-on consistency of each power unit 130 in the second bridge arm 120 can be verified based on the turn-on electrical parameters, thereby realizing the analysis of the dynamic characteristics of each power unit 130 in the second bridge arm 120 when used in series.

[0100] In some feasible embodiments, refer to Figure 9 The test system also includes a DC voltage source 400, a first switching unit 500, and an energy storage unit 600. The first end of the DC voltage source 400 is connected to the first end of the first switching unit 500. The second end of the first switching unit 500 is connected to the first end of the first bridge arm 110 and the first end of the energy storage unit 600. The second end of the first bridge arm 110 is connected to the first end of the second bridge arm 120. The second end of the DC voltage source 400 is connected to the second end of the second bridge arm 120 and the second end of the energy storage unit 600.

[0101] Specifically, the test system provides DC voltage to the first bridge arm 110 and the second bridge arm 120 during the test through a power supply circuit consisting of a DC voltage source 400, a first switching unit 500, and a power storage unit 600. The DC voltage source 400 supplies power to the first bridge arm 110 and the second bridge arm 120, the power storage unit 600 maintains the DC voltage supplied to the first bridge arm 110 and the second bridge arm 120 at a target voltage value, and the first switching unit 500 controls whether the DC voltage source 400 charges the power storage unit 600. As an example, the power storage unit 600 can specifically be a storage capacitor.

[0102] As an example, the first switching unit 500 may be a high-voltage circuit breaker, a contactor, or a high-power relay, but is not limited to these. The first switching unit 500 is used to control the connection and disconnection of the DC voltage source 400. When the first switching unit 500 is closed, the DC voltage source 400 continuously charges the energy storage unit 600. When the first switching unit 500 is open, the DC voltage source 400 no longer charges the energy storage unit 600, and the energy storage unit 600 discharges to the first bridge arm 110 and the second bridge arm 120.

[0103] In this embodiment, the DC voltage source 400 can continuously charge the energy storage unit 600 when the first switching unit 500 is closed, enabling the energy storage unit 600 to store electrical energy. When the energy storage unit 600 discharges, it maintains the DC voltage supplied to the first bridge arm 110 and the second bridge arm 120 at a target voltage value. It is understood that through the energy storage of the energy storage unit 600, the power of the DC voltage source 400 can be much less than the rated power of each power unit 130 in the first bridge arm 110 and the second bridge arm 120, which greatly reduces the cost of the DC voltage source 400.

[0104] In some feasible embodiments, reference continues to be made to Figure 9 The test system also includes a discharge unit 800 and a second switch unit 700. The first end of the discharge unit 800 is connected to the first end of the second switch unit 700, the second end of the discharge unit 800 is connected to the second end of the DC voltage source 400, and the second end of the second switch unit 700 is connected to the first end of the DC voltage source 400.

[0105] Specifically, the test system also includes a discharge unit 800 and a second switching unit 700. The discharge circuit composed of the discharge unit 800 and the second switching unit 700 is used for rapid discharge after the test. The second switching unit 700 is used to control the connection and disconnection of the DC voltage source 400. When the second switching unit 700 is closed, the electrical energy on the first bridge arm 110, the second bridge arm 120, and the energy storage unit 600 can be released to the discharge unit 800. As an example, the discharge unit 800 can specifically discharge a resistor.

[0106] Specifically, after the test is completed, the second switch unit 700 is closed. When the second switch unit 700 is closed, the electrical energy on the first bridge arm 110, the second bridge arm 120, and the energy storage unit 600 can be released to the discharge unit 800. This achieves the safe release of electrical energy on the first bridge arm 110, the second bridge arm 120, and the energy storage unit 600.

[0107] In conjunction with the above embodiments, and referring to Figure 10 After connecting the converter valve 100 to the test system, the specific test procedure for the test system provided in this application embodiment includes the following steps:

[0108] Step 1: The test module 300 generates a control signal, which is configured to set the effective pulse width of the first activation pulse to the first preset duration, set the effective pulse width of the second activation pulse to the third preset duration, and set the transmission time interval between the first activation pulse and the second activation pulse to the second preset duration.

[0109] Step 2: Close the first switch unit 500, and the DC voltage source 400 will charge the energy storage unit 600 to the preset test target voltage.

[0110] Step 3: Disconnect the first switch unit 500, and the energy storage unit 600 provides the test target voltage to the first bridge arm 110 and the second bridge arm 120.

[0111] Step 4: The test module 300 sends control signals to each power unit 130 in the second bridge arm 120.

[0112] Step 5: The test module 300 collects the electrical parameters of each power unit 130 in the second bridge arm 120.

[0113] Step 6: Close the second switch unit 700 to safely release the energy in the energy storage unit 600, the first bridge arm 110, and the second bridge arm 120, thus completing the test.

[0114] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0115] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0116] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A testing system for the power unit in a converter valve, characterized in that, The converter valve includes a first bridge arm and a second bridge arm connected in series, and both the first bridge arm and the second bridge arm include multiple power units connected in series. The testing system includes: A load, the load being used to connect to both ends of the first bridge arm; A test module, wherein the test module is used to connect to each of the power units in the second bridge arm; wherein the test module is configured to: While each power unit in the first bridge arm remains off, each power unit in the second bridge arm is controlled to perform a switching action, and the electrical parameters of each power unit in the second bridge arm are collected. Each electrical parameter is used to determine the test result.

2. The testing system according to claim 1, characterized in that, The test module is configured as follows: A control signal is synchronously sent to each of the power units in the second bridge arm to control each of the power units in the second bridge arm to perform switching operations; wherein, the control signal is used to control each of the power units in the second bridge arm to turn on for a first preset time and then turn off for a second preset time, and then turn on for a third preset time after turning off for the second preset time.

3. The testing system according to claim 2, characterized in that, The control signal includes a first turn-on pulse and a second turn-on pulse. The effective pulse width of the first turn-on pulse is the first preset duration, and the effective pulse width of the second turn-on pulse is the third preset duration. The test module is configured as follows: The first activation pulse is synchronously sent to each of the power units in the second bridge arm, and after the second preset time after the first activation pulse ends, the second activation pulse is synchronously sent to each of the power units in the second bridge arm.

4. The testing system according to claim 3, characterized in that, Both the first preset duration and the third preset duration are greater than the preset on-state duration; wherein, the on-state duration is the minimum duration from the turn-off to the steady-state turn-on of each power unit in the second bridge arm.

5. The testing system according to claim 3, characterized in that, The second preset duration is greater than the preset off-state duration; wherein, the off-state duration is the minimum duration from turn-on to steady-state off for each power unit in the second bridge arm.

6. The testing system according to claim 3, characterized in that, The electrical parameters of each power unit in the second bridge arm include turn-off electrical parameters and turn-on electrical parameters, and the test module is configured as follows: The shutdown electrical parameters of each power unit in the second bridge arm are collected, and each shutdown electrical parameter is used to determine the shutdown consistency of each power unit in the second bridge arm; wherein, the shutdown electrical parameters are the electrical parameters of each power unit in the second bridge arm within the second preset time period; The power-on electrical parameters of each power unit in the second bridge arm are collected, and each power-on electrical parameter is used to determine the power-on consistency of each power unit in the second bridge arm; wherein, the power-on electrical parameters are the electrical parameters of each power unit in the second bridge arm within the third preset time period.

7. The testing system according to claim 1, characterized in that, The test system further includes a DC voltage source, a first switching unit, and an energy storage unit. The first end of the DC voltage source is connected to the first end of the first switching unit. The second end of the first switching unit is connected to the first end of the first bridge arm and the first end of the energy storage unit. The second end of the first bridge arm is connected to the first end of the second bridge arm. The second end of the DC voltage source is connected to the second end of the second bridge arm and the second end of the energy storage unit.

8. The testing system according to any one of claims 1 to 7, characterized in that, The power unit includes a fully controlled switching device and an anti-parallel diode. The cathode of the anti-parallel diode is connected to the current input terminal of the fully controlled switching device, and the anode of the anti-parallel diode is connected to the current output terminal of the fully controlled switching device. The control terminal of the fully controlled switching device is connected to the test module.

9. The testing system according to claim 8, characterized in that, The power unit further includes an absorption circuit, the first end of which is connected to the cathode of the anti-parallel diode and the current input terminal of the fully controlled switching device, and the second end of which is connected to the anode of the anti-parallel diode and the current output terminal of the fully controlled switching device.

10. The testing system according to claim 9, characterized in that, The absorption circuit includes a clamping diode, an absorption capacitor, and an absorption resistor. The anode of the clamping diode is connected to the cathode of the anti-parallel diode and the current input terminal of the fully controlled switching device. The cathode of the clamping diode is connected to the first terminal of the absorption capacitor and the first terminal of the absorption resistor. The second terminal of the absorption capacitor is connected to the anode of the anti-parallel diode, the current output terminal of the fully controlled switching device, and the second terminal of the absorption resistor.

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