WO2022083788A1

WO2022083788A1 - Composite voltage test device for dc link capacitor

Info

Publication number: WO2022083788A1
Application number: PCT/CN2021/133164
Authority: WO
Inventors: 孙晓武; 李印达; 郭向明; 曹崇峰; 冯申荣
Original assignee: 无锡市电力滤波有限公司
Priority date: 2020-12-28
Filing date: 2021-11-25
Publication date: 2022-04-28
Also published as: ZA202201243B; CN112379310A

Abstract

A composite voltage testing device for a DC link capacitor, primarily consisting of a direct-current test circuit (1), a power frequency test circuit (2), a high-frequency test circuit (3), a measurement circuit (4) and a control circuit (5). An output end of the direct-current test circuit (1) is connected in parallel to one end of the measurement circuit (4), and the other end of the measurement circuit (4) is connected in parallel to the power frequency test circuit (2) and one end of the high-frequency test circuit (3) respectively. The control circuit (5) comprises signal acquisition (51), control output (52), and a controller (53). The signal acquisition (51) of the control loop (5) comes from the measurement circuit (4), and the control output (52) of the control circuit (5) is respectively connected to the direct-current test circuit (1), the power frequency test circuit (2), the high-frequency test circuit (3), and the measurement circuit (4). The invention features a simple structure, convenient operation, and is able to satisfy the voltage testing requirements for DC link capacitors.

Description

A composite voltage test device for DC support capacitors

This application claims the priority of the Chinese patent application filed on December 28, 2020 with the application number 202011574330.3 and the invention titled "A composite voltage test device for DC support capacitors", the entire contents of which are incorporated by reference in in this application.

technical field

The invention belongs to the technical field of capacitor testing, in particular to a composite voltage testing device for DC support capacitors.

Background technique

The DC support capacitor is one of the important components of the converter, and its main function is to act as an energy storage element on the DC side of the converter. Metallized film capacitors have advantages over electrolytic capacitors in terms of high voltage, high frequency, high temperature, high current, small size and long life. Therefore, metallized film DC support capacitors are widely used in high-performance converters such as rail transit, flexible DC transmission, and wind power photovoltaics. achievement.

When a traditional DC capacitor works, the current is zero. The DC support capacitor is different from the traditional DC capacitor. In actual operation, in addition to the DC voltage, the ripple voltage is also applied to the DC support capacitor, resulting in ripple current.

The voltage breakdown and insulation characteristics of capacitors under DC and AC voltage conditions are different, and the working field strength is also very different. The working field strength of the AC capacitor is 40-60V/μm. The working field strength of the DC capacitor is more than 200V/μm.

Important voltage test items for capacitors: thermal stability test, durability test, and inter-electrode withstand voltage test.

At present, most of the capacitor test devices can only use a single DC voltage source, a power frequency voltage source or a variable frequency power supply. Therefore, the DC support capacitor test can only reflect the characteristics of the capacitor under a single DC voltage, power frequency voltage source or variable frequency voltage, and cannot reflect the working characteristics of the DC support capacitor under actual working conditions.

In order to better design a reasonable DC support capacitor, it is necessary to accurately grasp the insulation characteristics and life characteristics of the actual working conditions of the DC support capacitor.

Therefore, it is necessary to design a new DC support capacitor voltage test device, which can solve the technology of superposition of different types of voltage sources to meet the test requirements of DC support capacitors.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a composite voltage test device for DC support capacitors in order to overcome the disadvantage that most of the existing test devices can only reflect the characteristics of capacitors under a single DC voltage source, power frequency voltage source or variable frequency power supply.

For achieving the above object, the present invention provides the following scheme:

The utility model relates to a composite voltage test device for DC support capacitors. The composite voltage test device for DC support capacitors is mainly composed of a DC test circuit, a power frequency test circuit, a high frequency test circuit, a test circuit and a control circuit.

The output end of the DC test loop is connected in parallel with one end of the test loop.

The other end of the test loop is connected in parallel with the power frequency test loop and the high frequency test loop respectively.

The control loop includes signal acquisition, control output, and controller. The signal acquisition for the control loop comes from the test loop. The control output of the control loop is respectively connected to the DC test loop, the power frequency test loop, the high frequency test loop and the test loop. The controller gives the command to control the output according to the signal acquisition and calculation.

The DC test loop includes a first power supply, a first switch, a first voltage regulator, a first step-up transformer, a high-voltage silicon stack, a current limiting resistor, a DC filter capacitor, a DC filter resistor, and an AC isolation inductor.

The power frequency test loop includes a second power supply, a second switch, a second voltage regulator, a second step-up transformer, a power frequency compensation reactor, a third switch, and a power frequency DC blocking capacitor.

The high-frequency test loop includes a third power supply, a fourth switch, a high-frequency power supply, a filter, a high-frequency compensation reactor, a fifth switch, and a high-frequency DC blocking capacitor.

The test loop includes a sixth switch, a discharge resistor, a voltage measurement part, a current measurement part, and a DC support capacitor to be tested.

One end of the first power source is connected to one end of the first switch. The other end of the first switch is connected to one end of the primary side of the first voltage regulator. The other end of the first power supply is connected to the other end of the primary side of the first voltage regulator. The secondary side of the first voltage regulator is connected in parallel with the primary side of the first step-up transformer. One end of the secondary side of the first step-up transformer is sequentially connected in series with a high-voltage silicon stack and a current limiting resistor. One end of the current limiting resistor is connected in parallel with a DC filter capacitor, and a DC filter resistor and an AC blocking inductor are connected in series at the same time. One end of the isolation inductance is connected to the high voltage end of the test loop. The other end of the secondary side of the first step-up transformer is connected in parallel with the other end of the DC filter capacitor and the low-voltage end of the test loop, and is grounded.

One end of the second power source is connected to one end of the second switch. The other end of the second switch is connected to one end of the primary side of the second voltage regulator. The other end of the second power supply is connected to the other end of the primary side of the second voltage regulator. The secondary side of the second voltage regulator is connected in parallel with the primary side of the second step-up transformer. The secondary side of the second step-up transformer is connected in parallel with the power frequency compensation reactor. The high voltage end of the power frequency compensation reactor is sequentially connected in series with the third switch and the power frequency DC blocking capacitor. The other end of the power frequency DC blocking capacitor is connected to the high voltage end of the test loop. The low-voltage end of the power frequency compensation reactor is connected in parallel with the low-voltage end of the test loop and is grounded.

The third power source is connected to the fourth switch and the high frequency power source in sequence. The high frequency power supply output end is connected with the filter input end. The output end of the filter is connected in parallel with the high-frequency compensation reactor. The high-voltage end of the high-frequency compensation reactor is sequentially connected in series with the fifth switch and the high-frequency DC blocking capacitor. The other end of the high-frequency DC blocking capacitor is connected to the high-voltage end of the test loop. The low-voltage end of the high-frequency compensation reactor is connected in parallel with the low-voltage end of the test loop and grounded.

The sixth switch is connected in series with the discharge resistor and then connected in parallel with the voltage measuring component. The DC support capacitor to be tested is connected in series with the current measuring part and also connected in parallel with the voltage measuring part.

Signal acquisition includes voltage signals, current signals, and other signals, and other signals include temperature, pressure, and the like.

The control output includes a first output, a second output, a third output, and a fourth output.

The DC filter capacitor and the DC filter resistor form an RC filter, which can stabilize the DC voltage applied to the DC support capacitor to be tested.

When the first switch is in the closed state, the second switch and the fourth switch are in the open state, the output voltage of the composite voltage test device is only DC voltage at this time, and the DC withstand voltage test and DC durability test can be carried out.

When the second switch is in the closed state and the first switch and the fourth switch are in the divided state, the output voltage of the composite voltage test device is only the power frequency voltage at this time, and the power frequency thermal stability test can be carried out.

When the fourth switch is in the closed state, and the first switch and the second switch are in the split state, the output voltage of the composite voltage test device is only high-frequency voltage at this time, and the high-frequency thermal stability test can be carried out.

When the first switch, the second switch, and the third switch are all in the closed state, and the fourth switch is in the open state, the output voltage of the composite voltage test device is a DC voltage superimposed frequency voltage, which can be used for thermal stability test, durability test sex test.

When the first switch, the fourth switch, and the fifth switch are all in the closed state, and the second switch is in the open state, the composite voltage test device outputs the DC voltage and superimposes the high-frequency voltage at this time, and the thermal stability test, durability test can be carried out. test.

When the second switch, the third switch, the fourth switch, and the fifth switch are all in the closed state, and the first switch is in the divided state, the composite voltage test device outputs the power frequency voltage and superimposes the high frequency voltage at this time, which can be used for thermal stability. test.

When the first switch, the second switch, the third switch, the fourth switch, and the fifth switch are all in the closed state, the composite voltage test device outputs a DC voltage superimposed on a high frequency voltage and a high frequency voltage, and the thermal stability test can be carried out. Durability test.

The commands of the first output, the first output, and the third output correspond to the first switch, the second switch, and the fourth switch, respectively. When the measurement signal is abnormal, the controller gives corresponding instructions.

When the test is over or the test is abnormal, the controller gives the fourth output command, and after the sixth switch is closed, the energy on the DC support capacitor to be tested is released through the discharge resistor.

Further, the first power supply is conventionally 220VAC, the second power supply is conventionally 380VAC, and the third power supply is conventionally 380VAC.

Further, the capacity of the first step-up transformer is 30KVA, and the transformation ratio is 0.4/7kV.

Further, the capacity of the second step-up transformer is 100KVA, and the transformation ratio is 0.4/3kV.

Further, the frequency range of the variable frequency power supply is 100-2500HZ, and the power is 100KVA.

Further, the voltage measurement component adopts a voltage measurement meter.

Further, other signals (temperature, pressure, etc.) are placed with relevant sensors on the tested DC support capacitors (Cx).

Further, the current maximum 10mF is selected for the power frequency DC blocking capacitor and the high frequency DC blocking capacitor.

Further, the inductive reactance of the power frequency compensation reactor is adjustable, and the sum of the capacitive reactance of the power frequency DC blocking capacitor and the DC support capacitor to be tested matches the inductive reactance of the power frequency compensation reactor. At this time, the second step-up transformer minimum output power.

Further, the inductive reactance of the high-frequency compensation reactor is adjustable, and the sum of the capacitive reactance of the high-frequency DC blocking capacitor and the DC support capacitor to be tested matches the inductive reactance of the high-frequency compensation reactor (under the condition of the test frequency). The output power output by the high frequency power supply is the smallest.

According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

It can realize various voltage forms, and can realize AC and DC withstand voltage test, thermal stability test, and durability test, which is in line with the actual working conditions of DC support capacitors. The test operation is simple, easy to maintain, high reliability, and good safety.

The invention has the advantages of simple structure and convenient operation, and can meet the voltage test requirements of the DC support capacitor.

Instruction drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative labor.

Fig. 1 is the structural representation of the implementation of the present invention;

FIG. 2 is a schematic diagram of wiring implemented by the present invention.

Symbol Description:

1-DC test loop; 2-Power frequency test loop; 3-High frequency test loop; 4-Test loop; 5-Control loop;

51-signal acquisition; 52-control output; 53-controller;

511-voltage signal; 512-current signal; 513-other signal;

521-first output; 522-second output; 523-third output; 523-fourth output;

U _S1 - first power supply; S ₁ - first switch; BT ₁ - first voltage regulator; T ₁ - first step-up transformer; D - high voltage silicon stack; R ₁ - current limiting resistor; C ₁ - DC filter Capacitor; R ₂ - DC filter resistance; L ₁ - AC blocking inductance;

U _S2 - second power supply; S ₂ - second switch; BT ₂ - second voltage regulator; T ₂ - second step-up transformer; L ₂ - power frequency compensation reactor; S ₃ - third switch; C ₂ - Power frequency DC blocking capacitors;

U _S3 - third power supply; S ₄ - fourth switch; BP - high frequency power supply; LB - filter; L ₃ - high frequency compensation reactor; S ₅ - fifth switch; C ₃ - high frequency DC blocking capacitor; GND-ground;

S ₆ - sixth switch; R ₃ - discharge resistance; V - voltage measuring part; TA - current measuring part; C _x - DC support capacitor to be tested.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

As can be seen in Figure 1, the present invention: the composite voltage test device is mainly composed of a DC test circuit (1), a power frequency test circuit (2), a high frequency test circuit (3), a test circuit (4) and a control circuit (5). .

It can be seen from Figure 2 that:

The output end of the DC test loop (1) is connected in parallel with one end of the test loop (4).

The other end of the test loop (4) is connected in parallel with one end of the power frequency test loop (2) and the high frequency test loop (3) respectively.

The control loop (5) includes a signal acquisition (51), a control output (52), and a controller (53); the signal acquisition (51) of the control loop (5) comes from the test loop (4). The control output of the control loop (5) is respectively connected to the DC test loop (1), the power frequency test loop (2), the high frequency test loop (3) and the test loop (4). The controller (53) calculates and gives instructions to control the output (52) according to the signal acquisition (51).

The DC test loop (1) includes a first power supply (U _S1 ), a first switch (S ₁ ), a first voltage regulator (BT ₁ ), a first step-up transformer (T ₁ ), a high-voltage silicon stack (D), Current limiting resistor (R ₁ ), DC filter capacitor (C ₁ ), DC filter resistor (R ₂ ), AC blocking inductor (L ₁ ).

The power frequency test loop (2) includes a second power supply (U _S2 ), a second switch (S ₂ ), a second voltage regulator (BT ₂ ), a second step-up transformer (T ₂ ), and a power frequency compensation reactor ( L ₂ ), the third switch (S ₃ ), and the power frequency DC blocking capacitor (C ₂ ).

The high-frequency test loop (3) includes a third power supply (U _S3 ), a fourth switch (S ₄ ), a high-frequency power supply (BP), a filter (LB), a high-frequency compensation reactor (L ₃ ), and a fifth switch (S ₅ ), high frequency DC blocking capacitor (C ₃ ).

The test loop (4) includes a sixth switch (S ₆ ), a discharge resistor (R ₃ ), a voltage measuring part (V), a current measuring part (TA), a DC support capacitor (C _x ) to be tested.

One end of the first power supply (U _S1 ) is connected with one end of the first switch (S ₁ ); the other end of the first switch (S ₁ ) is connected with one end of the primary side of the first voltage regulator (BT ₁ ); the first power supply The other end of (U _S1 ) is connected to the other end of the primary side of the first voltage regulator (BT ₁ ); the secondary side of the first voltage regulator (BT ₁ ) is connected in parallel with the primary side of the first step-up transformer (T ₁ ) connection; one end of the secondary side of the first step-up transformer (T ₁ ) is sequentially connected in series with a high-voltage silicon stack (D) and a current limiting resistor (R ₁ ); one end of the current limiting resistor (R ₁ ) is connected in parallel with a DC filter capacitor (C ₁ ). ), the DC filter resistor (R ₂ ) and the AC isolation inductance (L ₁ ) are connected in series at the same time; one end of the AC isolation inductance (L ₁ ) is connected to the high voltage end of the test loop (4); the (T ₁ ) pair of the first step-up transformer The other end of the side is connected in parallel with the other end of the DC filter capacitor (C ₁ ) and the low-voltage end of the test loop (4), and is grounded (GND).

One end of the second power source (U _S2 ) is connected to one end of the second switch (S ₂ ); the other end of the second switch (S ₂ ) is connected to one end of the primary side of the second voltage regulator (BT ₂ ); the second power source The other end of (U _S2 ) is connected to the other end of the primary side of the second voltage regulator (BT ₂ ); the secondary side of the second voltage regulator (BT ₂ ) is connected in parallel with the primary side of the second step-up transformer (T2) ; The secondary side of the second step-up transformer (T ₂ ) is connected in parallel with the power frequency compensation reactor (L2); the high voltage end of the power frequency compensation reactor (L ₂ ) is connected to the third switch (S ₃ ), the power frequency The direct capacitor (C ₂ ) is connected in series; the other end of the power frequency DC blocking capacitor (C ₂ ) is connected to the high voltage end of the test circuit (4); the low voltage end of the power frequency compensation reactor (L ₂ ) is connected to the low voltage end of the test circuit (4) Connect in parallel, and ground (GND).

The third power supply (U _S3 ) is connected to the fourth switch (S ₄ ) and the high frequency power supply (BP) in sequence; the output end of the high frequency power supply (BP) is connected to the input end of the filter (LB); the output end of the filter (LB) It is connected in parallel with the high-frequency compensation reactor (L ₃ ); the high-voltage end of the high-frequency compensation reactor (L ₃ ) is connected in series with the fifth switch (S ₅ ) and the high-frequency DC blocking capacitor (C ₃ ) in sequence; The other end of the direct capacitor (C ₃ ) is connected to the high-voltage end of the test circuit (4); the low-voltage end of the high-frequency compensation reactor (L ₃ ) is connected in parallel with the low-voltage end of the test circuit (4) and grounded (GND).

The sixth switch (S ₆ ) is connected in series with the discharge resistor (R ₃ ) and then connected in parallel with the voltage measuring part (V); the DC support capacitor (C _x ) to be tested is connected in series with the current measuring part (TA) and also connected with the voltage measuring part (V) Parallel connection.

The signal acquisition (51) includes a voltage signal (511), a current signal (512), and other signals (513), and the other signals (513) include temperature, pressure, and the like.

The control output (52) includes a first output (521), a second output (522), a third output (523), and a fourth output (524).

The DC filter capacitor (C ₁ ) and the DC filter resistor (R ₁ ) constitute an RC filter, which can stabilize the DC voltage applied to the DC support capacitor (C _x ) to be tested.

When the first switch (S ₁ ) is in the closed state, and the second switch (S ₂ ) and the fourth switch (S ₄ ) are in the open state, the output voltage of the composite voltage test device is only DC voltage at this time, and the DC withstand voltage can be carried out. Pressure test, DC durability test.

When the second switch (S ₂ ) is in the closed state, and the first switch (S ₁ ) and the fourth switch (S ₄ ) are in the divided state, the output voltage of the composite voltage test device is only the power frequency voltage at this time, and the work can be carried out. Frequency thermal stability test.

When the fourth switch (S ₄ ) is in the closed state, and the first switch (S ₁ ) and the second switch ( S ₂ ) are in the open state, the output voltage of the composite voltage test device is only high-frequency voltage at this time, and high Frequency thermal stability test.

When the first switch (S ₁ ), the second switch (S ₂ ), and the third switch (S ₃ ) are all in the closed state, and the fourth switch (S ₄ ) is in the open state, the composite voltage testing device outputs voltage at this time For DC voltage stacking frequency voltage, thermal stability test and durability test can be carried out.

When the first switch (S ₁ ), the fourth switch (S ₄ ), and the fifth switch (S ₅ ) are all in the closed state, and the second switch (S ₂ ) is in the open state, the composite voltage test device outputs the voltage at this time DC voltage is superimposed on high frequency voltage, and thermal stability test and durability test can be carried out.

When the second switch (S ₂ ), the third switch (S ₃ ), the fourth switch (S ₄ ), and the fifth switch (S ₅ ) are all in the closed state, and the first switch (S ₁ ) is in the open state, At this time, the composite voltage test device outputs power frequency voltage and superimposed high frequency voltage, and can carry out thermal stability test.

When the first switch (S ₁ ), the second switch (S ₂ ), the third switch (S ₃ ), the fourth switch (S ₄ ), and the fifth switch (S ₅ ) are all in the closed state, the composite voltage test device will When outputting DC voltage, superimposing frequency voltage and superimposing high frequency voltage, thermal stability test and durability test can be carried out.

The instructions of the first output (521), the first output (522), and the third output (523) correspond to the first switch (S ₁ ), the second switch (S ₂ ), and the fourth switch ( S ₃ ), respectively. When the measurement signal is abnormal, the controller (53) gives first output (521), first output (522), and third output (523) instructions accordingly.

When the test is over or the test is abnormal, the controller (53) gives a fourth output (524) command, at this time the sixth switch (S ₆ ) is closed, the discharge resistor (R ₃ ) and the DC support capacitor to be tested ( C _x ) constitutes a discharge circuit that releases the energy stored in the DC support capacitor (C _x ) to be tested.

Further, the inductive reactance value of the power frequency compensation reactor (L ₂ ) is adjustable, and the sum of the capacitive reactance of the power frequency DC blocking capacitor (C ₂ ) and the DC support capacitor (C _x ) to be tested is the same as the power frequency compensation reactor. The inductive reactance of (L ₂ ) is matched, and the output power of the second step-up transformer (T ₂ ) is at a minimum at this time.

Further, the inductive reactance value of the high-frequency compensation reactor (L ₃ ) can be adjusted, and the sum of the capacitive reactance of the high-frequency DC blocking capacitor (C ₃ ) and the DC support capacitor to be tested (C _x ) and the high-frequency compensation reactor The inductive reactance of (L ₃ ) is matched (under the condition of the test frequency), and the output power of the high-frequency power supply (BP) is the smallest at this time.

In this paper, specific examples are used to illustrate the principles and implementations of the present invention. The descriptions of the above embodiments are only used to help understand the methods and core ideas of the present invention; meanwhile, for those skilled in the art, according to the present invention There will be changes in the specific implementation and application scope. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims

A composite voltage test device for a DC support capacitor is characterized in that the composite voltage test device for a DC support capacitor is mainly composed of a DC test loop, a power frequency test loop, a high frequency test loop, a test loop and a control loop;

The output end of the DC test loop is connected in parallel with one end of the test loop, the other end of the test loop is connected in parallel with one end of the power frequency test loop and the high frequency test loop, respectively, and the control loop includes signal acquisition, control output, control The controller of the control loop gives the command of the control output according to the calculation result of the signal collection, the signal collection of the control loop comes from the test loop, and the control output of the control loop is respectively connected to the DC test loop, the power frequency test loop, High-frequency test loops and test loops.
The composite voltage test device for DC support capacitors according to claim 1, wherein the DC test circuit comprises a first power supply, a first switch, a first voltage regulator, a first step-up transformer, a high-voltage silicon stack, Current limiting resistor, DC filter capacitor, DC filter resistor, AC blocking inductor;

One end of the first 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 side of the first voltage regulator, and the other end of the first power supply is connected to the first voltage regulator. The other end of the primary side is connected, the secondary side of the first voltage regulator is connected in parallel with the primary side of the first step-up transformer, and one end of the secondary side of the first step-up transformer is sequentially connected in series with a high-voltage silicon stack, a current limiting resistor , one end of the current limiting resistor is connected in parallel with a DC filter capacitor, and at the same time, a DC filter resistor and an AC isolation inductance are connected in series. The other end of the DC filter capacitor and the low-voltage end of the test loop are connected in parallel and grounded.
The composite voltage test device for DC support capacitors according to claim 1, wherein the power frequency test loop comprises a second power supply, a second switch, a second voltage regulator, a second step-up transformer, and a power frequency compensation Reactor, third switch, power frequency DC blocking capacitor;

One end of the second power supply is connected to one end of the second switch, the other end of the second switch is connected to one end of the primary side of the second voltage regulator, and the other end of the second power supply is connected to the second voltage regulator. The other end of the primary side is connected in parallel, the secondary side of the second voltage regulator is connected in parallel with the primary side of the second step-up transformer, the secondary side of the second step-up transformer is connected in parallel with the power frequency compensation reactor, and the power frequency compensation reactor is connected in parallel. The high voltage end of the frequency compensation reactor is sequentially connected in series with the third switch and the power frequency DC blocking capacitor.
The composite voltage test device for DC support capacitors according to claim 1, wherein the high-frequency test loop comprises a third power supply, a fourth switch, a high-frequency power supply, a filter, a high-frequency compensation reactor, a fifth Switches, high frequency DC blocking capacitors;

The third power supply is connected to the fourth switch and the high-frequency power supply in sequence, the high-frequency power supply output end is connected to the filter input end, the filter output end is connected in parallel with the high-frequency compensation reactor, and the high-frequency compensation reactor is connected in parallel. The high-voltage end of the reactor is sequentially connected in series with the fifth switch and the high-frequency DC blocking capacitor.
The composite voltage test device for a DC support capacitor according to claim 1, wherein the test loop comprises a sixth switch, a discharge resistor, a voltage measurement component, a current measurement component, and the DC support capacitor to be tested;

The sixth switch is connected in series with the discharge resistor and then connected in parallel with the voltage measuring component, and the DC support capacitor to be tested is connected in series with the current measuring component and then connected in parallel with the voltage measuring component.