Thermal stability aging test circuit and method for direct current support capacitor

Abstract

The invention discloses a thermal stability aging test circuit and method for a DC support capacitor. The test circuit comprises an output circuit breaker, a single-phase voltage source generator and a controller. The single-phase voltage source generator comprises a phase-shifting transformer and a variable-frequency power supply; the first end of the phase-shifting transformer is connected with an AC power supply, the second end of the phase-shifting transformer is connected with the first end of the variable-frequency power supply, and the second end of the variable-frequency power supply is connected with a to-be-tested capacitor through the output circuit breaker; the controller is used for controlling the single-phase voltage source generator to output a test signal to be applied to the capacitor to be tested, and the test signal comprises at least one of a direct-current signal or an alternating-current signal; the DC signal comprises a DC voltage, and the AC signal comprises an AC voltage of one or more frequencies. The test circuit can provide alternating current test voltages with different frequencies for the direct current support capacitor, and the test circuit is high in stability.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a thermal stability aging test circuit and method for a DC-supported capacitor. Background Technology

[0002] In recent years, flexible DC transmission technology has developed rapidly, and DC support capacitors are an important core component supporting flexible DC transmission. DC support capacitors specifically refer to capacitors used in power modules of flexible DC transmission projects or large-capacity power electronic devices to stabilize the DC bus voltage. They are characterized by higher withstand voltage, larger operating current, and higher energy storage density, and their performance directly affects the reliable operation of the flexible DC transmission system.

[0003] Thermal stability aging tests on DC-supported capacitors are a core reliability test item for evaluating the reliability and lifespan of DC-supported capacitors under long-term high-temperature operating conditions. Related technologies apply a DC voltage and a single-frequency AC voltage to the DC-supported capacitor simultaneously through an AC / DC superimposed power supply circuit. However, in actual operation, DC-supported capacitors withstand voltages of multiple frequencies, and applying only a single-frequency AC voltage cannot adequately simulate actual operating conditions. Furthermore, to achieve AC / DC isolation, a DC blocking capacitor is required. Failure of the DC blocking capacitor can affect the entire experimental process, necessitating that the DC blocking capacitor have higher stability than the DC-supported capacitor under test, resulting in higher test costs and lower reliability. Summary of the Invention

[0004] In view of this, this application provides a thermal stability aging test circuit and method for DC-supported capacitors, which can provide AC test voltages of different frequencies for DC-supported capacitors, and the test circuit has high stability.

[0005] To solve the above problems, the technical solution provided in this application is as follows:

[0006] In a first aspect of this application, a thermal stability aging test circuit for a DC-supported capacitor is provided, comprising: an output circuit breaker, a single-phase voltage source generator, and a controller; the single-phase voltage source generator comprises: a phase-shifting transformer and a frequency converter.

[0007] The first end of the phase-shifting transformer is used to connect to the AC power supply, the second end of the phase-shifting transformer is connected to the first end of the frequency converter, and the second end of the frequency converter is used to connect to the capacitor under test through the output circuit breaker.

[0008] A controller is used to control the output test signal of a single-phase voltage source generator to be applied to the capacitor under test. The test signal includes at least one of a DC signal or an AC signal; the DC signal includes a DC voltage, and the AC signal includes an AC voltage of one or more frequencies.

[0009] In one possible implementation, the frequency converter includes an AC / DC conversion circuit, a DC / AC conversion circuit, and a DC / DC conversion circuit. The AC / DC conversion circuit is used to convert the output voltage of the phase-shifting transformer into DC power, the DC / AC conversion circuit is used to convert the DC power into AC voltage in the test signal, and the DC / DC conversion circuit is used to convert the DC power into DC voltage in the test signal.

[0010] The controller is used to adjust the phase angle of the output voltage of the phase-shifting transformer by changing the connection method of the secondary winding of the phase-shifting transformer, and to adjust the amplitude or frequency of the AC voltage output by the frequency converter by controlling the modulation wave of the DC / AC conversion circuit.

[0011] One possible implementation is that the test signal includes a DC voltage and an AC voltage of one or more frequencies;

[0012] The controller, used to control the single-phase voltage source generator to output a test signal and apply it to the capacitor under test, includes:

[0013] The controller is used to control the output AC voltage of the single-phase voltage source generator. When the AC voltage meets the AC voltage requirement of the capacitor under test, it controls the output DC voltage of the single-phase voltage source generator. When the DC voltage meets the DC voltage requirement of the capacitor under test, it closes the output circuit breaker and applies the test signal to the capacitor under test.

[0014] Alternatively, the controller is used to first control the single-phase voltage source generator to output DC voltage. If the DC voltage meets the DC voltage requirement of the capacitor under test, the controller controls the single-phase voltage source generator to output AC voltage. If the AC voltage output meets the AC voltage requirement of the capacitor under test, the controller closes the output circuit breaker and applies the test signal to the capacitor under test.

[0015] One possible implementation is that the test signal includes a DC voltage and an AC voltage of one or more frequencies;

[0016] The controller, used to control the single-phase voltage source generator to output a test signal and apply it to the capacitor under test, includes:

[0017] The controller is used to control the AC current corresponding to the AC voltage output by the single-phase voltage source generator. When the AC current meets the AC current requirement of the capacitor under test, it controls the single-phase voltage source generator to output DC voltage. When the DC voltage meets the DC voltage requirement of the capacitor under test, it closes the output circuit breaker and applies the test signal to the capacitor under test.

[0018] Alternatively, the controller is used to first control the output DC voltage of the single-phase voltage source generator, and when the DC voltage meets the DC voltage requirement of the capacitor under test, control the output AC current corresponding to the AC voltage of the single-phase voltage source generator; when the AC current meets the AC current requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0019] In one possible implementation, the single-phase voltage source generator further includes a filter circuit;

[0020] The filter circuit is used to filter out harmonics in the test signal.

[0021] In a second aspect of this application, a thermal stability aging test method for a DC-supported capacitor is provided. The test method is applied to a thermal stability aging test circuit for a DC-supported capacitor. The test circuit includes: an output circuit breaker, a single-phase voltage source generator, and a controller. The single-phase voltage source generator includes: a phase-shifting transformer and a frequency converter. The first terminal of the phase-shifting transformer is used to connect to an AC power source, and the second terminal of the phase-shifting transformer is connected to the first terminal of the frequency converter. The second terminal of the frequency converter is used to connect to the capacitor under test through the output circuit breaker.

[0022] The method includes:

[0023] The single-phase voltage source generator outputs a test signal to be applied to the capacitor under test. The test signal includes at least one of a DC signal or an AC signal; the DC signal includes a DC voltage, and the AC signal includes an AC voltage of one or more frequencies.

[0024] In one possible implementation, the frequency converter includes an AC / DC conversion circuit, a DC / AC conversion circuit, and a DC / DC conversion circuit. The AC / DC conversion circuit is used to convert the output voltage of the phase-shifting transformer into DC power, the DC / AC conversion circuit is used to convert the DC power into AC voltage in the test signal, and the DC / DC conversion circuit is used to convert the DC power into DC voltage in the test signal.

[0025] The methods include: adjusting the phase angle of the output voltage of the phase-shifting transformer by changing the connection method of the secondary winding of the phase-shifting transformer, and adjusting the amplitude or frequency of the AC voltage output by the frequency converter by controlling the modulation wave of the DC / AC conversion circuit.

[0026] One possible implementation is that the test signal includes a DC voltage and an AC voltage of one or more frequencies;

[0027] The single-phase voltage source generator outputs a test signal to be applied to the capacitor under test, including:

[0028] Control the single-phase voltage source generator to output AC voltage. When the AC voltage meets the AC voltage requirement of the capacitor under test, control the single-phase voltage source generator to output DC voltage. When the DC voltage meets the DC voltage requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0029] Alternatively, control the single-phase voltage source generator to output DC voltage. If the DC voltage meets the DC voltage requirement of the capacitor under test, control the single-phase voltage source generator to output AC voltage. If the output AC voltage meets the AC voltage requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0030] One possible implementation is that the test signal includes a DC voltage and an AC voltage of one or more frequencies;

[0031] The single-phase voltage source generator outputs a test signal to be applied to the capacitor under test, including:

[0032] Control the single-phase voltage source generator to output AC current corresponding to the AC voltage. When the AC current meets the AC current requirement of the capacitor under test, control the single-phase voltage source generator to output DC voltage. When the DC voltage meets the DC voltage requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0033] Alternatively, control the single-phase voltage source generator to output DC voltage. If the DC voltage meets the DC voltage requirement of the capacitor under test, control the single-phase voltage source generator to output AC current corresponding to the AC voltage. If the AC current meets the AC current requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0034] In one possible implementation, the single-phase voltage source generator further includes a filter circuit;

[0035] The filter circuit is used to filter out harmonics in the test signal.

[0036] The thermal stability aging test circuit for DC-supported capacitors provided in this application includes a single-phase voltage source generator and a controller. The controller can be used to control the single-phase voltage source generator to output a test signal and apply it to the capacitor under test. The test signal includes at least one of DC voltage or AC voltages of various frequencies. Since the single-phase voltage source generator can output AC voltages of various frequencies, it can better simulate the voltage and current stresses experienced by the DC-supported capacitor under actual operating conditions, resulting in higher test realism. Furthermore, according to test requirements, the controller can control the single-phase voltage source generator to output different types of test signals, thereby performing different types of tests on the capacitor under test, making the test circuit highly flexible. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of an MCC type voltage source converter valve;

[0038] Figure 2 This is a schematic diagram of an MCC-type voltage source converter valve power module;

[0039] Figure 3 This is a schematic diagram of a thermal stability aging test circuit for a capacitor in related technologies;

[0040] Figure 4 A schematic diagram of a thermal stability aging test circuit for a DC-supported capacitor provided in an embodiment of this application;

[0041] Figure 5 A schematic diagram of another thermal stability aging test circuit for a DC-supported capacitor provided in an embodiment of this application;

[0042] Figure 6 This is a flowchart of a thermal stability aging test method for a DC-supported capacitor provided in an embodiment of this application. Detailed Implementation

[0043] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0044] Modular commutated converter (MCC) type voltage source converter valves are core devices in flexible DC transmission. (See also...) Figure 1 The figure shows a schematic diagram of an MCC type voltage source converter valve. Figure 1 In the converter, SM1, SM2 and up to SMn are the power modules generated by the converter.

[0045] The DC support capacitor is an important support component in voltage source converter valves. (See also...) Figure 2 The figure shows a schematic diagram of an MCC type voltage source converter valve power module.

[0046] Figure 2 In this context, Co represents the DC-supported capacitor. In practical applications, the capacitance of the DC-supported capacitor Co is typically between 3mF and 15mF, much larger than that of ordinary power electronic capacitors.

[0047] See Figure 3 The figure is a schematic diagram of a thermal stability aging test circuit for a capacitor in related technologies.

[0048] Figure 3In the related technology shown, the primary side of transformer 302 is connected to AC power supply 301, and the secondary side of transformer 302 is connected to test capacitor 304 through DC blocking capacitor 303 to provide AC voltage required for thermal stability testing of test capacitor 304. DC power supply 305 is connected to test capacitor 304 through diode 306 to provide DC voltage required for aging testing of test capacitor 304.

[0049] In flexible DC transmission projects, the voltage stress borne by the DC support capacitor is... As shown in equation (1), current stress As shown in equation (2) below.

[0050]

[0051]

[0052] In equations (1) and (2), DC voltage Let ω be the angular frequency of the nth AC voltage. Let n be the phase angle of the nth AC voltage. Let n be the amplitude of the nth AC voltage. Let be the amplitude of the nth alternating current.

[0053] As can be seen from equations (1) and (2), the voltage and current that the DC support capacitor bears during actual operation are not of a single frequency, but include multiple AC harmonic components in addition to the fundamental frequency. Figure 3 The AC power supply 301 shown can only provide AC voltage of a single frequency to the test capacitor 304, which cannot meet the needs of simulating actual operating conditions.

[0054] Moreover, given that the capacitance of the DC-supported capacitor is already much larger than that of ordinary power electronic capacitors, Figure 3 The DC blocking capacitor 303 shown needs to have higher performance than the test capacitor 304 for the test to proceed smoothly, resulting in low reliability and high cost for the test circuit. Furthermore, for Figure 3 For the DC side of the test circuit, the DC blocking capacitor 303 is connected in parallel with the test capacitor 304. Figure 3 On the AC side of the test circuit, the DC blocking capacitor 303 is connected in series with the test capacitor 304, which increases the voltage requirements for the AC power supply 301 and the DC power supply 305.

[0055] Therefore, in order to make the test environment of DC-supported capacitors closer to actual operating conditions, this application provides a thermal stability aging test circuit and method for DC-supported capacitors.

[0056] See Figure 4The figure is a schematic diagram of a thermal stability aging test circuit for a DC-supported capacitor provided in an embodiment of this application.

[0057] The test circuit provided in this application embodiment includes: an output circuit breaker QF0, a single-phase voltage source generator 10, and a controller 20; the single-phase voltage source generator 10 includes: a phase-shifting transformer 101 and a frequency converter 102.

[0058] The first end of the phase-shifting transformer 101 is used to connect to the AC power supply, and the second end of the phase-shifting transformer 101 is connected to the first end of the frequency converter 102. The second end of the frequency converter 102 is used to connect the capacitor under test Ct through the output circuit breaker QF0.

[0059] The controller 20 is used to control the single-phase voltage source generator 10 to output a test signal and apply it to the capacitor under test Ct. The test signal includes at least one of a DC signal or an AC signal; the DC signal includes a DC voltage, and the AC signal includes an AC voltage of one or more frequencies or an AC current of one or more frequencies. Since the single-phase voltage source generator 10 can generate AC voltages or AC currents of various frequencies, it can better simulate the multiple AC harmonic components that the capacitor under test Ct experiences under actual operating conditions, resulting in a higher degree of realism in the test.

[0060] Because the controller 20 can be used to control the single-phase voltage source generator 10 to apply a DC voltage to the capacitor under test Ct for aging tests; it can also be used to control the single-phase voltage source generator 10 to apply AC voltages of different frequencies to the capacitor under test Ct for thermal stability tests; and it can also be used to control the single-phase voltage source generator 10 to simultaneously apply a DC voltage and multiple AC voltages of different frequencies to the capacitor under test Ct for thermal stability aging tests. Therefore, the test circuit provided in this application embodiment can adapt to various testing needs of the capacitor C and is highly flexible.

[0061] The thermal stability aging test circuit for a DC-supported capacitor provided in this application includes a single-phase voltage source generator and a controller. The controller can be used to control the single-phase voltage source generator to output a test signal and apply it to the capacitor under test. The test signal includes at least one of a DC voltage or an AC voltage of various frequencies. Since the single-phase voltage source generator can output AC voltages of various frequencies, it can better simulate the voltage and current stresses experienced by the DC-supported capacitor under actual operating conditions, resulting in higher test realism. Furthermore, according to test requirements, the controller can control the single-phase voltage source generator to output different types of test signals, thereby performing different types of tests on the capacitor under test, making the test circuit highly flexible.

[0062] The following will continue to combine Figure 4The specific method by which the controller 20 controls the output test signal of the single-phase voltage source generator 10 will be further explained.

[0063] In one possible implementation, the frequency converter 102 includes an AC / DC conversion circuit, a DC / AC conversion circuit, and a DC / DC conversion circuit. The AC / DC conversion circuit converts the output voltage of the phase-shifting transformer into DC power, the DC / AC conversion circuit converts the DC power into AC voltage in the test signal, and the DC / DC conversion circuit converts the DC power into DC voltage in the test signal.

[0064] The controller 20 is used to adjust the phase angle of the output voltage of the phase-shifting transformer 101 by changing the connection method of the secondary winding of the phase-shifting transformer 101, and to adjust the amplitude or frequency of the AC voltage output by the frequency converter 102 by controlling the modulation wave of the DC / AC conversion circuit.

[0065] Specifically, the AC voltage source can be a 10kV AC bus. The controller 20 can be used to select the turns ratio of the phase-shifting transformer 101 to change the amplitude of the output voltage of the phase-shifting transformer 101. The controller 20 can also be used to change the connection method of the secondary winding of the phase-shifting transformer 101 to adjust the phase angle of the output voltage of the phase-shifting transformer 101. It should be understood that the phase angle of the output voltage of the phase-shifting transformer 101 is the same as the phase angle of the output voltage of the frequency converter 102.

[0066] In one possible implementation, the AC / DC circuit in the inverter power supply 102 converts the output voltage of the phase-shifting transformer 101 into DC power. The controller 20 can adjust the amplitude of the DC power by controlling the duty cycle of the pulse width modulation (PWM) wave of the AC / DC circuit. The controller 20 can be used to adjust the amplitude or frequency of the AC voltage output by the inverter power supply 102 by controlling the modulation wave of the DC / AC conversion circuit. For example, the inverter power supply 102 may include multiple DC / AC conversion circuits. The controller 20 can send PWM waves with corresponding duty cycles to each DC / AC conversion circuit according to the amplitude of the target AC voltage, and the controller 20 can send PWM waves with corresponding frequencies to each DC / AC conversion circuit according to the frequency of the target AC voltage, so that different DC / AC circuits can output AC voltages with different amplitudes or frequencies, that is, the inverter power supply 102 can output multiple AC voltages with different amplitudes or frequencies.

[0067] In one possible implementation, the controller 20 can also be used to adjust the amplitude of the DC voltage output by the inverter power supply 102 by controlling the duty cycle of the PWM wave of the DC / DC circuit.

[0068] This application does not specifically limit the amplitude, frequency, or phase angle of the test signal output by the single-phase voltage source generator. The amplitude, frequency, or phase angle of the DC voltage and AC voltage in the test signal can be adjusted according to actual experimental requirements. In one possible implementation, the phase angle of the AC voltage can be between 0 degrees and 360 degrees, and the frequency of the AC voltage can be between 15 Hz and 3000 Hz.

[0069] The thermal stability aging test circuit for DC-supported capacitors provided in this application embodiment allows the amplitude, frequency, or phase angle of the test signal output by the single-phase voltage source generator to be adjusted according to actual test requirements. This enables more flexible application of various combinations of voltages to the capacitor under test (Ct), thereby simulating the voltage and current stresses borne by the capacitor under test (Ct) under different operating conditions. The test circuit exhibits high flexibility.

[0070] In one possible implementation, the test signal includes a DC voltage and an AC voltage, wherein the AC voltage may include one or more frequencies.

[0071] The specific loading method of the test circuit provided in the embodiments of this application will be further described below.

[0072] Since it is impossible to apply an infinite number of AC signals of different frequencies during actual experiments, the test signal may include k AC signals of different frequencies. The voltage stress experienced by the capacitor under test during the test. As shown in equation (3), current stress As shown in equation (4) below.

[0073]

[0074]

[0075] In equations (3) and (4), k is the maximum number of AC signals of different frequencies that can be applied to the test circuit.

[0076] Specifically, the controller can be used to control the output AC voltage of the single-phase voltage source generator. When the AC voltage meets the AC voltage requirements of the capacitor under test, the controller can control the output DC voltage of the single-phase voltage source generator. When the DC voltage meets the DC voltage requirements of the capacitor under test, the controller can close the output circuit breaker and apply the test signal to the capacitor under test.

[0077] This application does not specifically limit the output order of DC voltage and AC voltage of the single-phase voltage source generator. The above embodiment is described with AC voltage output first as an example. The following is described with DC voltage output first as an example.

[0078] Specifically, the controller controls the output DC voltage of the single-phase voltage source generator. When the DC voltage meets the DC voltage requirement of the capacitor under test, the controller controls the output AC voltage of the single-phase voltage source generator. When the AC current of the output voltage meets the AC voltage requirement of the capacitor under test, the controller closes the output circuit breaker and applies the test signal to the capacitor under test.

[0079] In one possible implementation, the controller is also configured to control the single-phase voltage source generator to re-output the DC voltage when the DC voltage output by the single-phase voltage source generator does not meet the DC voltage requirement of the capacitor under test; and to control the single-phase voltage source generator to re-output the AC voltage when the AC voltage output by the single-phase voltage source generator does not meet the AC voltage requirement of the capacitor under test.

[0080] The test circuit provided in this application embodiment has a controller that controls the single-phase voltage source generator to output AC voltage first and then DC voltage, or to output DC voltage first and then AC voltage. When the DC voltage and AC voltage meet the DC voltage requirements and AC voltage requirements of the capacitor under test, respectively, the test signal is applied to the capacitor under test, thereby reducing the resonance phenomenon caused by the simultaneous output of AC voltage and DC voltage.

[0081] It is understandable that, neglecting transient processes, the voltage and current across a capacitor have a definite functional relationship; that is, changing either the voltage or the current will simultaneously change the other. Furthermore, since the capacitive reactance of a capacitor decreases rapidly with increasing frequency, the change in voltage across the capacitor with increasing current becomes increasingly insignificant. Therefore, alternating current can be chosen as the control variable to better apply alternating current signals of different frequencies to the capacitor under test.

[0082] When AC current is selected as the control variable, the voltage stress borne by the capacitor under test during the test. As shown in equation (5) below.

[0083]

[0084] In equation (5), C is the capacitance value of the capacitor under test.

[0085] Specifically, the controller is used to control the AC current corresponding to the AC voltage output by the single-phase voltage source generator. When the AC current meets the AC current requirement of the capacitor under test, the controller controls the single-phase voltage source generator to output a DC voltage. When the DC voltage meets the DC voltage requirement of the capacitor under test, the controller closes the output circuit breaker and applies a test signal to the capacitor under test.

[0086] This application does not specifically limit the output order of DC voltage and AC current of the single-phase voltage source generator. The above embodiments are described with AC current output first as an example. The following embodiments are described with DC voltage output first as an example.

[0087] Specifically, the controller is used to first control the output DC voltage of the single-phase voltage source generator, and when the DC voltage meets the DC voltage requirement of the capacitor under test, control the output AC current corresponding to the AC voltage of the single-phase voltage source generator; when the AC current meets the AC current requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0088] The test circuit provided in this application embodiment has a clear functional relationship between the AC current and AC voltage of the capacitor. The controller outputs the AC voltage in the test signal by controlling the output AC current of the single-phase voltage source generator. By detecting whether the AC current meets the AC current requirement of the capacitor under test, the controller detects whether the AC voltage meets the AC voltage requirement of the capacitor under test. The differences between AC currents of different frequencies are significant, thereby better applying the test signal to the capacitor under test.

[0089] In one possible implementation, the controller is also configured to control the single-phase voltage source generator to re-output a DC voltage when the DC voltage output by the single-phase voltage source generator does not meet the DC voltage requirement of the capacitor under test; and to control the single-phase voltage source generator to re-output an AC current when the AC current output by the single-phase voltage source generator does not meet the AC current requirement of the capacitor under test.

[0090] In one possible implementation, the single-phase voltage source generator in the test circuit provided in this application embodiment further includes a filter circuit.

[0091] See Figure 5 The figure is a schematic diagram of another thermal stability aging test circuit for a DC-supported capacitor provided in an embodiment of this application.

[0092] Figure 5 In this circuit, the AC voltage source is a 10kV AC bus. The first terminal of the filter circuit 103 is connected to the second terminal of the frequency converter 102, and the second terminal of the filter circuit 103 is connected to the first terminal of the output circuit breaker QF0. The filter circuit 103 is used to filter out unwanted high-frequency harmonics from the capacitor under test in the test signal.

[0093] The test circuit provided in this application embodiment also includes a filter circuit, which can filter out high-frequency harmonics that are not needed by the capacitor under test in the test signal, so that the test signal can more accurately provide the required voltage stress and current stress of the capacitor under test.

[0094] In one possible implementation, the test circuit also includes an incoming line switch and an input circuit breaker.

[0095] See also Figure 5 The 10kV AC busbar is connected to the first terminal of the input circuit breaker QF2 via the incoming line switch QF1. The input circuit breaker QF2 is used to connect to the first terminal of the phase-shifting transformer 101. The incoming line switch QF1 and the input circuit breaker QF2 are used to control the AC busbar to provide AC power to the phase-shifting transformer.

[0096] Based on the thermal stability aging test circuit for DC-supported capacitors provided in the above embodiments, this application also provides a thermal stability aging test method for DC-supported capacitors. The thermal stability aging test method for DC-supported capacitors provided in this application is applied to the thermal stability aging test circuit for DC-supported capacitors in the above embodiments. The test circuit includes: an output circuit breaker, a single-phase voltage source generator, and a controller; the single-phase voltage source generator includes: a phase-shifting transformer and a frequency converter; the first terminal of the phase-shifting transformer is used to connect to an AC power supply, the second terminal of the phase-shifting transformer is connected to the first terminal of the frequency converter, and the second terminal of the frequency converter is used to connect the capacitor under test through the output circuit breaker.

[0097] See Figure 6 The figure is a flowchart of a thermal stability aging test method for a DC-supported capacitor provided in an embodiment of this application.

[0098] The method includes:

[0099] S601: Controls the output test signal of the single-phase voltage source generator to be applied to the capacitor under test. The test signal includes at least one of a DC signal or an AC signal. The DC signal includes a DC voltage, and the AC signal includes an AC voltage of one or more frequencies.

[0100] For example, the controller controls the single-phase voltage source generator to output a test signal to the capacitor under test, and the test signal includes at least one of a DC signal or an AC signal.

[0101] The test method provided in this application embodiment can control a single-phase voltage source generator to output a test signal and apply it to the capacitor under test. The test signal includes at least one of DC voltage or AC voltages of various frequencies. Since the single-phase voltage source generator can output AC voltages of various frequencies, it can better simulate the voltage and current stresses experienced by the DC-supported capacitor under actual operating conditions, resulting in higher test realism. Furthermore, the single-phase voltage source generator can be configured to output different types of test signals according to test requirements, thereby enabling different types of tests to be performed on the capacitor under test, thus providing high flexibility of the test circuit.

[0102] In one possible implementation, the frequency converter includes an AC / DC conversion circuit, a DC / AC conversion circuit, and a DC / DC conversion circuit. The AC / DC conversion circuit is used to convert the output voltage of the phase-shifting transformer into DC power, the DC / AC conversion circuit is used to convert the DC power into AC voltage in the test signal, and the DC / DC conversion circuit is used to convert the DC power into DC voltage in the test signal.

[0103] The method includes: adjusting the phase angle of the output voltage of the phase-shifting transformer by changing the connection method of the secondary winding of the phase-shifting transformer, and adjusting the amplitude or frequency of the AC voltage output by the frequency converter by controlling the modulation wave of the DC / AC conversion circuit.

[0104] One possible implementation is that the test signal includes a DC voltage and an AC voltage of one or more frequencies;

[0105] The single-phase voltage source generator outputs a test signal to be applied to the capacitor under test, including:

[0106] Control the single-phase voltage source generator to output AC voltage. When the AC voltage meets the AC voltage requirement of the capacitor under test, control the single-phase voltage source generator to output DC voltage. When the DC voltage meets the DC voltage requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0107] Alternatively, control the single-phase voltage source generator to output DC voltage. If the DC voltage meets the DC voltage requirement of the capacitor under test, control the single-phase voltage source generator to output AC voltage. If the output AC voltage meets the AC voltage requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0108] One possible implementation is that the test signal includes a DC voltage and an AC voltage of one or more frequencies;

[0109] The single-phase voltage source generator outputs a test signal to be applied to the capacitor under test, including:

[0110] Control the single-phase voltage source generator to output AC current corresponding to the AC voltage. When the AC current meets the AC current requirement of the capacitor under test, control the single-phase voltage source generator to output DC voltage. When the DC voltage meets the DC voltage requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0111] Alternatively, control the single-phase voltage source generator to output DC voltage. If the DC voltage meets the DC voltage requirement of the capacitor under test, control the single-phase voltage source generator to output AC current corresponding to the AC voltage. If the AC current meets the AC current requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

[0112] In one possible implementation, the single-phase voltage source generator further includes a filter circuit;

[0113] The filter circuit is used to filter out harmonics in the test signal.

[0114] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0115] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thermal stability aging test circuit for a DC-supported capacitor, characterized in that, include: Output circuit breakers, single-phase voltage source generators, and controllers; The single-phase voltage source generator includes: a phase-shifting transformer and a frequency converter; The first end of the phase-shifting transformer is used to connect to an AC power source, the second end of the phase-shifting transformer is connected to the first end of the frequency converter, and the second end of the frequency converter is used to connect to the capacitor under test through the output circuit breaker. The controller is used to control the single-phase voltage source generator to output a test signal to the capacitor under test. The test signal includes at least one of a DC signal or an AC signal. The DC signal includes a DC voltage, and the AC signal includes an AC voltage of one or more frequencies.

2. The test circuit according to claim 1, characterized in that, The frequency converter includes an AC / DC conversion circuit, a DC / AC conversion circuit, and a DC / DC conversion circuit. The AC / DC conversion circuit is used to convert the output voltage of the phase-shifting transformer into DC power. The DC / AC conversion circuit is used to convert the DC power into the AC voltage in the test signal. The DC / DC conversion circuit is used to convert the DC power into the DC voltage in the test signal. The controller is used to adjust the phase angle of the output voltage of the phase-shifting transformer by changing the connection method of the secondary winding of the phase-shifting transformer, and to adjust the amplitude or frequency of the AC voltage output by the frequency converter by controlling the modulation wave of the DC / AC conversion circuit.

3. The test circuit according to claim 2, characterized in that, The test signal includes the DC voltage and the AC voltage of one or more frequencies; The controller is used to control the single-phase voltage source generator to output a test signal and apply it to the capacitor under test, including: The controller is used to control the single-phase voltage source generator to output the AC voltage; when the AC voltage meets the AC voltage requirement of the capacitor under test, the controller controls the single-phase voltage source generator to output the DC voltage; when the DC voltage meets the DC voltage requirement of the capacitor under test, the controller closes the output circuit breaker and applies the test signal to the capacitor under test. Alternatively, the controller is configured to first control the single-phase voltage source generator to output the DC voltage, and when the DC voltage meets the DC voltage requirement of the capacitor under test, control the single-phase voltage source generator to output the AC voltage; and when the AC voltage of the output voltage meets the AC voltage requirement of the capacitor under test, close the output circuit breaker to apply the test signal to the capacitor under test.

4. The test circuit according to claim 2, characterized in that, The test signal includes the DC voltage and the AC voltage of one or more frequencies; The controller is used to control the single-phase voltage source generator to output a test signal and apply it to the capacitor under test, including: The controller is used to control the single-phase voltage source generator to output the AC current corresponding to the AC voltage; when the AC current meets the AC current requirement of the capacitor under test, the controller controls the single-phase voltage source generator to output the DC voltage; when the DC voltage meets the DC voltage requirement of the capacitor under test, the controller closes the output circuit breaker and applies the test signal to the capacitor under test. Alternatively, the controller is configured to first control the single-phase voltage source generator to output the DC voltage; if the DC voltage meets the DC voltage requirement of the capacitor under test, control the single-phase voltage source generator to output the AC current corresponding to the AC voltage; if the AC current meets the AC current requirement of the capacitor under test, close the output circuit breaker and apply the test signal to the capacitor under test.

5. The test circuit according to any one of claims 1 to 4, characterized in that, The single-phase voltage source generator also includes: a filter circuit; The filtering circuit is used to filter out harmonics in the test signal.

6. A method for thermal stability aging test of a DC-supported capacitor, characterized in that, The test method is applied to the thermal stability aging test circuit of a DC-supported capacitor. The test circuit includes: an output circuit breaker, a single-phase voltage source generator, and a controller. The single-phase voltage source generator includes: a phase-shifting transformer and a frequency converter. The first terminal of the phase-shifting transformer is used to connect to an AC power source, and the second terminal of the phase-shifting transformer is connected to the first terminal of the frequency converter. The second terminal of the frequency converter is used to connect to the capacitor under test through the output circuit breaker. The method includes: The single-phase voltage source generator is controlled to output a test signal and apply it to the capacitor under test. The test signal includes at least one of a DC signal or an AC signal. The DC signal includes a DC voltage, and the AC signal includes an AC voltage of one or more frequencies.

7. The test method according to claim 6, characterized in that, The frequency converter includes an AC / DC conversion circuit, a DC / AC conversion circuit, and a DC / DC conversion circuit. The AC / DC conversion circuit is used to convert the output voltage of the phase-shifting transformer into DC power. The DC / AC conversion circuit is used to convert the DC power into AC voltage in the test signal. The DC / DC conversion circuit is used to convert the DC power into DC voltage in the test signal. The method includes: adjusting the phase angle of the output voltage of the phase-shifting transformer by changing the connection method of the secondary winding of the phase-shifting transformer, and adjusting the amplitude or frequency of the AC voltage output by the frequency converter by controlling the modulation wave of the DC / AC conversion circuit.

8. The test method according to claim 7, characterized in that, The test signal includes the DC voltage and the AC voltage of one or more frequencies; The step of controlling the single-phase voltage source generator to output a test signal and apply it to the capacitor under test includes: The single-phase voltage source generator is controlled to output the AC voltage. When the AC voltage meets the AC voltage requirement of the capacitor under test, the single-phase voltage source generator is controlled to output the DC voltage. When the DC voltage meets the DC voltage requirement of the capacitor under test, the output circuit breaker is closed to apply the test signal to the capacitor under test. Alternatively, the single-phase voltage source generator is controlled to output the DC voltage. If the DC voltage meets the DC voltage requirement of the capacitor under test, the single-phase voltage source generator is controlled to output the AC voltage. If the AC voltage of the output voltage meets the AC voltage requirement of the capacitor under test, the output circuit breaker is closed to apply the test signal to the capacitor under test.

9. The test method according to claim 7, characterized in that, The test signal includes the DC voltage and the AC voltage of one or more frequencies; The step of controlling the single-phase voltage source generator to output a test signal and apply it to the capacitor under test includes: The single-phase voltage source generator is controlled to output an AC current corresponding to the AC voltage. When the AC current meets the AC current requirement of the capacitor under test, the single-phase voltage source generator is controlled to output a DC voltage. When the DC voltage meets the DC voltage requirement of the capacitor under test, the output circuit breaker is closed to apply the test signal to the capacitor under test. Alternatively, the single-phase voltage source generator is controlled to output the DC voltage. If the DC voltage meets the DC voltage requirement of the capacitor under test, the single-phase voltage source generator is controlled to output the AC current corresponding to the AC voltage. If the AC current meets the AC current requirement of the capacitor under test, the output circuit breaker is closed to apply the test signal to the capacitor under test.

10. The test method according to any one of claims 6 to 9, characterized in that, The single-phase voltage source generator also includes: a filter circuit; The filtering circuit is used to filter out harmonics in the test signal.

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