A high-voltage direct-current support capacitor insulation resistance measuring device

Abstract

The utility model discloses a kind of high-voltage direct-current support capacitor insulation resistance measuring device and method, high-voltage direct-current support capacitor insulation resistance measuring device includes direct current charging test loop, test loop, discharge test loop and control system, direct current charging test loop includes power supply, first switch, voltage regulator, step-up transformer, high-voltage silicon pile, current-limiting resistance and second switch, test loop includes third switch, first discharge resistance, voltmeter and the high-voltage direct-current support capacitor to be tested, discharge test loop includes fourth switch, second discharge resistance, fifth switch and voltage divider, control system includes signal acquisition, control output and controller.The utility model simple structure, it is easy to operate, can satisfy the insulation resistance measurement test demand of high voltage, large capacity direct current support container.

Description

Technical Field

[0001] This utility model belongs to the field of capacitor testing technology, specifically relating to a high-voltage DC supported capacitor insulation resistance measuring device. Background Technology

[0002] DC support capacitors are key components of converters, primarily serving functions such as voltage equalization, energy storage, and filtering. Currently, high-power converters, such as high-voltage frequency converters in the tens of megawatt range, high-speed train converters, high-power STATCOM, and DC capacitors used in flexible DC transmission projects, all require high-voltage, high-capacity DC support capacitors. These capacitors are characterized by high voltage and large capacitance, with voltages up to 6kV DC, capacitances up to 10mF, and weights reaching up to 300kg.

[0003] These types of DC-supported capacitors use metallized polypropylene film as the dielectric, with zinc-aluminum alloy deposited on the surface of the polypropylene film as electrodes, led out through a sprayed metal layer. When a weak point in the polypropylene film breaks down, the electrodes evaporate and isolate the fault point, allowing the DC-supported capacitor to quickly restore insulation and continue normal operation; this process is called self-healing. DC-supported capacitors used for voltage equalization and energy storage can withstand DC field strengths exceeding 200 V / μm. For DC-supported capacitors applied to high field strengths, voltage drop is indicated by insulation resistance. In engineering, conductivity is one of the four major parameters of an insulator, and insulation resistance can also reflect the performance of the dielectric.

[0004] The document "JB / T 8168—2023 Pulse Capacitors and DC Capacitors" provides methods for measuring insulation resistance or self-discharge time constant, but does not provide related test circuits and related devices, and is mainly aimed at pulse capacitors and DC capacitors.

[0005] Document CN102435852A describes a method and apparatus for measuring the insulation resistance of metallized film capacitors under high electric field strength. This method calculates the insulation resistance of the metallized film capacitor under high electric field strength by sampling the resistor and the voltage division ratio of the capacitor under DC voltage. This method obtains the insulation resistance by applying voltage over a long period. This method can be used for small-capacity capacitors; however, it is not specified whether it is applicable to high-voltage, large-capacity DC-supported capacitors. This method differs from the three methods provided in document JB / T 8168—2023 Pulse Capacitors and DC Capacitors, which is an industry standard and its test methods have a certain degree of standardization and authority.

[0006] Document CN 106655321 A describes a flexible discharge device for measuring the leakage current / insulation resistance of electrolytic capacitors. Since electrolytic capacitors have relatively low voltages, typically 1000VDC, while DC-supported capacitors based on metallized films can operate at voltages up to 6000VDC, this flexible discharge device is not suitable for high-voltage DC-supported capacitors.

[0007] Currently, insulation resistance measurement of high-voltage DC-supported capacitors is not a required test item in type testing. The dielectric properties of high-voltage DC-supported capacitors are mainly analyzed by measuring their insulation resistance. Existing technologies are primarily geared towards electrolytic capacitors and metallized film capacitors under high field strength, and are not applicable to high-voltage, high-capacity DC-supported capacitors. Therefore, a device and method for measuring the insulation resistance of high-voltage DC-supported capacitors are needed to address these issues.

[0008] In summary, these types of devices and circuits represent technical problems that need to be addressed, and are also key technologies that need to be solved to improve the performance of high-voltage DC support capacitors. Summary of the Invention

[0009] In order to overcome the shortcomings of existing testing equipment technology, this utility model proposes a high-voltage DC supported capacitor insulation resistance measuring device.

[0010] The technical solution adopted in this utility model is as follows.

[0011] This utility model provides a high-voltage DC supported capacitor insulation resistance measuring device, which mainly consists of a DC charging test circuit, a test circuit, a discharge test circuit and a control system.

[0012] The DC charging test circuit includes a power supply, a first switch, a voltage regulator, a step-up transformer, a high-voltage silicon stack, a current-limiting resistor, and a second switch.

[0013] The test circuit includes a third switch, a first discharge resistor, a voltmeter, and a high-voltage DC support capacitor to be tested.

[0014] The discharge test circuit includes a fourth switch, a second discharge resistor, a fifth switch, and a voltage divider. The voltage divider consists of a high-voltage resistor and a low-voltage resistor connected in series, with the intermediate connection point being the high-voltage output terminal.

[0015] The control system includes signal acquisition, control output, and a controller. The signal acquisition for the control system comes from the test circuit and the discharge test circuit.

[0016] The output of the DC charging test circuit is connected in parallel with one end of the test circuit, and the other end of the test circuit is connected in parallel with the discharging test circuit. The control outputs of the control system are connected to the DC charging test circuit, the discharging test circuit, and the test circuit, respectively. The controller calculates and issues control output commands based on the acquired signals.

[0017] One end of the power supply is connected to one end of the first switch. The other end of the first switch is connected to one end of the primary winding of the voltage regulator. The other end of the power supply is connected to the other end of the primary winding of the voltage regulator. The secondary winding of the voltage regulator is connected in parallel to the primary winding of the step-up transformer. One end of the secondary winding of the step-up transformer is connected in series with a high-voltage silicon stack and a current-limiting resistor. One end of the current-limiting resistor is connected to the second switch. One end of the second switch is connected to the high-voltage terminal of the test circuit. The other end of the secondary winding of the step-up transformer is connected in parallel to the low-voltage terminal of the test circuit and grounded.

[0018] The third switch is connected in series with the first discharge resistor and then in parallel with the voltmeter. One end of the third switch is connected to one end of the second switch, and the other end of the first discharge resistor is connected to the voltmeter and grounded.

[0019] The high-voltage DC support capacitor to be tested is connected in parallel with the voltmeter, and one end of the DC support capacitor to be tested is connected to the grounding line.

[0020] One end of the fourth switch is connected to one end of the high-voltage DC support capacitor to be tested. The other end of the fourth switch is connected to the second discharge resistor and one end of the fifth switch. The other end of the second discharge resistor is connected to the other end of the high-voltage DC support capacitor to be tested. The fifth switch is connected in series with the voltage divider. The low-voltage resistor of the voltage divider is connected to the other end of the second discharge resistor and then to ground.

[0021] Signal acquisition includes voltage signals and other signals, including temperature and pressure.

[0022] The control outputs include the first output, the second output, the third output, the fourth output, and the fifth output.

[0023] Specifically, the power supply is typically 220V AC.

[0024] Specifically, the step-up transformer has a capacity of 30KVA and a turns ratio of 0.4 / 15kV.

[0025] Specifically, the voltmeter is a high-impedance digital voltmeter (input impedance 1000MΩ).

[0026] Specifically, other signals (temperature and pressure, etc.) are detected by placing relevant sensors on the high-voltage DC support capacitor in the test.

[0027] This utility model also provides steps for measuring the insulation resistance of a high-voltage DC capacitor:

[0028] (1) Measure the actual capacitance of the DC-supported capacitor to be tested. C Then connect the test circuit;

[0029] (2) When the first and second switches are both closed, and the third, fourth, and fifth switches are all open, the DC charging test circuit charges the DC support capacitor under test. When the voltmeter reading reaches the test voltage value, the controller sends a relevant command to the control output. At this time, the first output sends a command to the second switch to open, and records the voltage at the start of self-discharge. U 0, record self-discharge time t The voltage after U t Insulation resistance R P The calculation formula is as follows:

[0030] R P = t / ( C *ln( U t / U 0));

[0031] (3) The controller sends relevant instructions to the control output, the second output sends the closing instruction to the fourth switch, the second discharge resistor discharges the DC support capacitor to be tested, and the reading of the voltmeter is observed; after 1 minute, the controller sends relevant instructions to the control output again, the third output sends the closing instruction to the fifth switch, the voltage signal is connected to the acquisition signal, when the voltage signal acquired is 0, the controller sends relevant instructions to the control output, at this time the second output sends the opening instruction to the fourth switch, and the measurement ends;

[0032] (4) When the test ends, the controller gives the fourth output command, the third switch closes and the remaining energy on the DC capacitor to be tested is released through the first discharge resistor. Then the controller gives the fifth output command and the first switch opens. At this time, the entire test device is in a power-off state.

[0033] (5) When the test is abnormal, other signals are abnormal. The controller gives the fourth output command. After the third switch is closed, the energy on the DC support capacitor to be tested is released through the first discharge resistor. Then the controller gives the fifth output command and the first switch is opened. At this time, the entire test device is in a power-off state.

[0034] The advantages of this invention are: it enables automatic and repeated measurement of the insulation resistance of high-voltage, large-capacity DC-supported containers; the test operation is simple, easy to maintain, highly reliable, and safe.

[0035] This invention has a simple structure and is easy to operate, and can meet the insulation resistance measurement test requirements of high-voltage, large-capacity DC-supported containers. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model;

[0037] Figure 2 This is a schematic diagram of the wiring in an embodiment of this utility model;

[0038] In the diagram, 1-DC charging test circuit; 2-Test circuit; 3-Discharging test circuit; 4-Control system;

[0039] 41 - Signal acquisition; 42 - Control output; 43 - Controller;

[0040] 411 - Voltage signal; 412 - Other signals;

[0041] 421 - First output; 422 - Second output; 423 - Third output; 424 - Fourth output; 425 - Fifth output;

[0042] Us - First power supply; S1 - First switch; BT - Voltage regulator; T - Step-up transformer; D - High-voltage silicon stack; R1 - Current-limiting resistor; S2 - Second switch;

[0043] S3 - Third switch; R2 - First discharge resistor; V - Voltmeter; Cx - High-voltage DC support capacitor to be tested;

[0044] S4 - Fourth switch; Rx - Second discharge resistor; S5 - Fifth switch; Vt - Voltage divider; RF1 - High voltage resistor of voltage divider; RF2 - Low voltage resistor of voltage divider. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0046] exist Figure 1 and Figure 2 As can be seen, the present invention: the high voltage DC support capacitor insulation resistance measuring device mainly consists of a DC charging test circuit (1), a test circuit (2), a discharge test circuit (3) and a control system (4);

[0047] The DC charging test circuit (1) includes a power supply (Us), a first switch (S1), a voltage regulator (BT), a step-up transformer (T), a high-voltage silicon stack (D), a current-limiting resistor (R1), and a second switch (S2);

[0048] The test circuit (2) includes a third switch (S3), a first discharge resistor (R2), a voltmeter (V), and a high-voltage DC support capacitor (Cx) to be tested;

[0049] The discharge test circuit (3) includes a fourth switch (S4), a second discharge resistor (Rx), a fifth switch (S5), and a voltage divider (Vt). The voltage divider (Vt) is formed by connecting the high voltage resistor (RF1) and the low voltage resistor (RF2) of the voltage divider in series, with the intermediate connection point being the high voltage output pole.

[0050] The control system (4) includes signal acquisition (41), control output (42), and controller (43). The signal acquisition (41) of the control system (4) comes from the test circuit (2) and the discharge test circuit (3).

[0051] The output of the DC charging test circuit (1) is connected in parallel with one end of the test circuit (2), and the other end of the test circuit (2) is connected in parallel with the discharge test circuit (3); the control output (42) of the control system (4) is connected to the DC charging test circuit (1), the discharge test circuit (2) and the test circuit (3) respectively, and the controller (43) calculates and gives the instruction of the control output (42) according to the signal acquisition (41);

[0052] One end of the power supply (Us) is connected to one end of the first switch (S1), the other end of the first switch (S1) is connected to one end of the primary side of the voltage regulator (BT), the other end of the power supply (Us) is connected to the other end of the primary side of the voltage regulator (BT), the secondary side of the voltage regulator (BT) is connected in parallel with the primary side of the step-up transformer (T), one end of the secondary side of the step-up transformer (T) is connected in series with the high-voltage silicon stack (D) and the current-limiting resistor (R1), one end of the current-limiting resistor (R1) is connected to the second switch (S2), one end of the second switch (S2) is connected to the high-voltage end of the test circuit (2), and the other end of the secondary side of the step-up transformer (T) is connected in parallel with the low-voltage end of the test circuit (2) and grounded;

[0053] The third switch (S3) is connected in series with the first discharge resistor (R2) and then connected in parallel with the voltmeter (V). One end of the third switch (S3) is connected to one end of the second switch (S2), and the other end of the first discharge resistor (R2) is connected to the voltmeter (V) and grounded.

[0054] The high-voltage DC support capacitor (Cx) to be tested is connected in parallel with the voltmeter (V), and one end of the DC support capacitor (Cx) to be tested is connected to the grounding line;

[0055] One end of the fourth switch (S4) is connected to one end of the high-voltage DC support capacitor (Cx) to be tested. The other end of the fourth switch (S4) is connected to one end of the second discharge resistor (Rx) and the fifth switch (S5). The other end of the second discharge resistor (Rx) is connected to the other end of the high-voltage DC support capacitor (Cx) to be tested. The fifth switch (S5) is connected in series with the voltage divider (Vt). The low-voltage resistor (RF2) of the voltage divider is connected to the other end of the second discharge resistor (Rx) and then connected to ground.

[0056] Signal acquisition (41) includes voltage signal (411) and other signals (412), which include temperature and pressure.

[0057] The control output (42) includes a first output (421), a second output (422), a third output (423), a fourth output (424), and a fifth output (425).

[0058] Specifically, the power supply (Us) is typically 220V AC.

[0059] Specifically, the step-up transformer (T) has a capacity of 30KVA and a turns ratio of 0.4 / 15kV.

[0060] Specifically, the voltmeter (V) is a high-impedance digital voltmeter (input impedance 1000MΩ).

[0061] Specifically, other signals (412) (temperature, pressure) are obtained by placing relevant sensors on the high voltage DC support capacitor (Cx) to be tested.

[0062] This utility model also provides steps for measuring the insulation resistance of a high-voltage DC capacitor:

[0063] (1) Measure the actual capacitance of the DC-supported capacitor (Cx) to be tested. C Then connect the test circuit (2);

[0064] (2) When the first switch (S1) and the second switch (S2) are both closed, and the third switch (S3), the fourth switch (S4), and the fifth switch (S5) are all open, the DC charging test circuit (1) charges the high-voltage DC support capacitor (Cx) to be tested; when the reading of the voltmeter (V) reaches the test voltage value, the controller (43) sends a relevant instruction to the control output (42), at which time the first output (421) sends a trip instruction to the second switch (S2) and records the voltage at the start of self-discharge. U 0, record self-discharge time t The voltage after U t Insulation resistance R P The calculation formula is as follows:

[0065] R P = t / ( C *ln( U t / U 0));

[0066] (3) The controller (43) sends relevant instructions to the control output (42), the second output (422) sends a closing instruction to the fourth switch (S4), the second discharge resistor (Rx) discharges the high voltage DC support capacitor (Cx) to be tested, and observes the reading of the voltmeter; after 1 minute, the controller (43) sends relevant instructions to the control output (42) again, the third output (423) sends a closing instruction to the fifth switch (S5), the voltage signal (411) is connected to the signal acquisition (41), when the voltage signal of the signal acquisition (41) is 0, the controller (43) sends relevant instructions to the control output (42), at this time the second output (422) sends a tripping instruction to the fourth switch (S4), and the measurement ends;

[0067] (4) When the test ends, the controller (43) gives the fourth output (424) command, the third switch (S3) closes and releases the remaining energy on the DC capacitor (Cx) to be tested through the first discharge resistor (R2), and then the controller (43) gives the fifth output (425) command, the first switch (S1) opens, and the entire test device is in a power-off state.

[0068] (5) When the test is abnormal, other signals (412) are abnormal, the controller (43) gives the fourth output (424) command, the third switch (S3) closes and releases the energy on the high voltage DC support capacitor (Cx) to be tested through the first discharge resistor (R2), then the controller (43) gives the fifth output (425) command, the first switch (S1) opens, and the entire test device is in a power-off state.

[0069] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A high-voltage DC supported capacitor insulation resistance measuring device, characterized in that: The high-voltage DC-supported capacitor insulation resistance measuring device includes a DC charging test circuit, a test circuit, a discharge test circuit, and a control system. The DC charging test circuit includes a power supply, a first switch, a voltage regulator, a step-up transformer, a high-voltage silicon stack, a current-limiting resistor, and a second switch. The test circuit includes a third switch, a first discharge resistor, a voltmeter, and the high-voltage DC-supported capacitor to be tested. The discharge test circuit includes a fourth switch, a second discharge resistor, a fifth switch, and a voltage divider. The voltage divider is composed of a high-voltage resistor and a low-voltage resistor connected in series. The control system includes signal acquisition, control output, and a controller. The signal acquisition comes from the test circuit and the discharge test circuit. The control output of the control system is connected to the DC charging test circuit, the discharge test circuit, and the test circuit, respectively. The output terminal of the DC charging test circuit is connected in parallel with one end of the test circuit, and the other end of the test circuit is connected in parallel with the discharge test circuit. One end of the power supply is connected to one end of the first switch, and the other end of the first switch is connected to one end of the primary winding of the voltage regulator. The other end of the power supply is also connected to the other end of the primary winding of the voltage regulator. The secondary winding of the voltage regulator is connected in parallel to the primary winding of the step-up transformer. One end of the secondary winding of the step-up transformer is connected in series with a high-voltage silicon stack and a current-limiting resistor. One end of the current-limiting resistor is connected to a second switch. One end of the second switch is connected to the high-voltage terminal of the test circuit. The other end of the secondary winding of the step-up transformer is connected in parallel to the low-voltage terminal of the test circuit and grounded. The third switch is connected in series with the first discharge resistor and then in parallel with a voltmeter. One end of the third switch is connected to one end of the second switch, and the first discharge resistor is connected to the other end of the voltmeter and grounded; the high-voltage DC support capacitor to be tested is connected in parallel with the voltmeter; one end of the fourth switch is connected to one end of the high-voltage DC support capacitor to be tested; the other end of the fourth switch is connected to the second discharge resistor and one end of the fifth switch; the other end of the second discharge resistor is connected to the other end of the high-voltage DC support capacitor to be tested; the fifth switch is connected in series with the voltage divider; the low-voltage resistor of the voltage divider is connected to the other end of the second discharge resistor and then connected to ground.

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