CN103499729B - A kind of measuring method of compensator with series capaci tance sparking distance equalizing capacitance intrinsic standoff ratio - Google Patents

Abstract

The present invention relates to the relevant technical field of series capacitor compensation devices, in particular to a method for measuring the voltage dividing ratio of voltage equalizing capacitors used in spark gaps of series capacitor compensation devices, including: disconnecting the electrical connection between the first capacitor branch and the low voltage end and/or disconnecting Opening the electrical connection between the second capacitor branch and the high-voltage terminal; applying the same test voltage to both ends of the first capacitor branch and the second capacitor branch, and the frequency of the test voltage is greater than or equal to 500 Hz; measuring the first The current of the capacitance branch obtains the first capacitance branch current, and the current of the second capacitance branch is measured to obtain the second capacitance branch current; the inverse ratio of the current ratio of the first capacitance branch current to the second capacitance branch current is used as the first capacitance branch current A voltage division ratio between the first capacitor branch and the second capacitor branch. By adopting the method of increasing the test frequency, the present invention can reduce the test voltage to below the safety voltage of 50V under the condition that the test current requirement is satisfied, improves the test safety, and has strong anti-power frequency interference capability.

Description

A method for measuring the voltage-dividing ratio of the equalizing capacitor used in the spark gap of a series capacitor compensation device

technical field

The invention relates to the related technical field of a series capacitor compensation device, in particular to a method for measuring the voltage division ratio of a voltage equalizing capacitor used in a spark gap of a series capacitor compensation device.

Background technique

The series capacitor compensation device can improve the transmission capacity and stability of the system. Its working principle is shown in Figure 1, where GAP is the spark gap and D is the damping circuit. The spark gap is a critical protection device for series capacitors. The voltage limiter (MOV) is the main protection of the series capacitor, that is, MOV1 and MOV2 in Figure 1, and the spark gap is the main protection of the MOV and the backup protection of the series capacitor. When a serious short-circuit fault occurs in the system, the capacitor is quickly overvoltage, and the MOV protection starts. Due to the limited energy bearing of the MOV, the spark gap should start protection at the millisecond level, and the spark gap fault will cause damage to the main equipment of the series capacitor compensation device. The voltage level of the series capacitor compensation device is getting higher and higher, often using multi-gap series operation, and using equalizing capacitors (C1, C2, C3 and C4) to equalize the trigger voltage, see Figure 2. The voltage equalizing capacitor has the characteristics of high voltage level (for example, a single capacitor reaches 67.5kV before the spark gap triggers), and small capacitance (for example, a single capacitor 3000pF), and is installed in the lower part of the spark gap, as shown in Figure 3, the spark gap itself The height reaches 10m, and it is installed on the series compensation platform about 10m above the ground. In order to ensure the reliable operation of the spark gap, the ratio of the terminal voltage of C1 and C2 to the total voltage is required to be 1/4, the ratio of the terminal voltage of C1 and C2 connected in series, and the voltage of C3 and C4 connected in series to the total voltage is 1/2. In engineering, C1, C2, C3 and C4 are usually required to be equal, and the capacitance value is tested by power frequency voltammetry and bridge method, and the voltage division ratio can be calculated, which is generally required to be within 5%.

Based on the above principles, the voltage division ratio can be obtained by testing the capacitance value of the voltage equalizing capacitor. However, due to the small capacitance, a high power frequency voltage source is required to apply voltage to the capacitor during equipment acceptance and maintenance, otherwise the test current signal is very weak (for example, the current measured when 220V is applied is about 200μA), and the equipment installation position is high. There are unsafe factors in the testing work under certain circumstances. In particular, the series compensation device is close to the high-voltage line in the substation, and the series compensation platform installed with the spark gap is strongly induced by power frequency, and the test current signal is easily disturbed. The voltage division ratio is calculated according to the test capacitance, and there are two test errors of voltage and current. In order to calculate the average value, at least dozens of tests are required, and the test accuracy and efficiency are poor.

Contents of the invention

Based on this, it is necessary to provide a series capacitance compensation device spark gap for the existing technical problems of low test accuracy, complicated test process and poor efficiency in the measurement of the voltage dividing ratio of the equalizing capacitor for the spark gap of the series capacitor compensation device. The measurement method of the voltage dividing ratio of the equalizing capacitor.

A method for measuring the voltage-dividing ratio of voltage equalizing capacitors for spark gaps in series capacitor compensation devices, the series capacitor compensation device includes at least two spark gap branches and at least two capacitor branches, and each spark gap branch includes at least one In the spark gap, each capacitor branch includes at least one capacitor, wherein the first spark gap branch is connected in parallel with the first capacitor branch to form a first spark capacitor branch, and the second spark gap branch is connected in parallel with the second capacitor branch to form a second spark gap branch. Two spark capacitor branches, one end of the first spark capacitor branch is a low voltage end, the other end of the first spark capacitor branch is connected in series with one end of the second spark capacitor branch, and the other end of the second spark capacitor branch is a high voltage end , the measurement method includes:

Disconnecting the electrical connection of the first capacitor branch from the low voltage terminal and/or disconnecting the electrical connection of the second capacitor branch from the high voltage terminal;

Applying the same test voltage to both ends of the first capacitor branch and the second capacitor branch, and the frequency of the test voltage is greater than or equal to 500 Hz;

measuring the current of the first capacitor branch to obtain the first capacitor branch current, and measuring the current of the second capacitor branch to obtain the second capacitor branch current;

The inverse ratio of the current ratio of the first capacitor branch current to the second capacitor branch current is used as the voltage division ratio between the first capacitor branch circuit and the second capacitor branch circuit.

Further, the first spark gap branch includes a first sealed spark gap, the second spark gap branch includes a second sealed spark gap, the first capacitor branch includes a first capacitor, and the second capacitor The branch includes a second capacitor.

Furthermore, a current testing device is used to measure the first capacitor branch current and the second capacitor branch current.

Preferably, the current testing device is a current testing instrument, and the frequency of the testing voltage is greater than or equal to 500 Hz and less than or equal to 1500 Hz.

Further, the first spark gap branch includes a first main spark gap, the second spark gap branch includes a second main spark gap, and the first capacitor branch includes a first capacitor and a second capacitor, so The second capacitor branch includes a third capacitor and a fourth capacitor.

Further, the series capacitor compensation device also includes a first sealed spark gap branch and a second sealed spark gap branch, the first sealed spark gap branch includes a first sealed spark gap, and the second sealed spark gap The gap branch includes a second sealed spark gap, the first capacitor is connected in parallel with the first sealed spark gap branch to form a first capacitor sealed spark gap branch, and the second capacitor is connected to the second sealed spark gap The branches are connected in parallel to form a second capacitively sealed spark gap branch, and the first capacitively sealed spark gap branch is connected in series with the second capacitively sealed spark gap branch.

Further, it also includes:

Applying the same test voltage to both ends of the first capacitor and the second capacitor;

measuring the current of the first capacitor to obtain the first capacitor current, and measuring the current of the second capacitor to obtain the second capacitor current;

The inverse ratio of the current ratio of the first capacitor current to the second capacitor current is used as the voltage division ratio of the first capacitor and the second capacitor.

Still further, a current testing device is used to measure the first capacitive current and the second capacitive current.

Preferably, the current testing device is a current testing instrument, and the frequency of the testing voltage is greater than or equal to 500 Hz and less than or equal to 1500 Hz.

Further, the test voltage is less than or equal to 50 volts.

By adopting the method of increasing the test frequency, the present invention can reduce the test voltage to be lower than the safety voltage 50V under the condition that the test current requirement is satisfied, improves the test safety, and has strong anti-power frequency interference capability.

At the same time, since the current ratio of the test parallel circuit is used instead of the capacitance ratio of the series circuit, the influence of the inductance of the test line and the influence of the common mode signal are offset, the test accuracy is improved, and the number of tests is reduced by at least half.

The measuring method of the invention reduces the test voltage, simplifies the test steps, reduces the test risk and improves the test precision.

Description of drawings

Figure 1 is a schematic diagram of the working principle of the series capacitor compensation device;

Figure 2 is a schematic diagram of the multi-gap series operation of the series capacitor compensation device, where M1 and M2 are the main gaps, T1 and T2 are the sealing gaps, C1, C2, C3, and C4 are voltage dividing capacitors, R1 and R2 are resistors, and A1 is the pulse Transformer, B1 is the high voltage side pulse transformer, G1 is the trigger circuit;

Figure 3 is a schematic diagram of the installation of the spark gap and its uniform capacitance;

Fig. 4 is the working flow chart of the measuring method of the voltage-dividing ratio of the voltage-equaling capacitor for a kind of series capacitor compensation device spark gap of the present invention;

Fig. 5 is a schematic diagram of the measurement method of the present invention.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 4, it is a working flow diagram of a method for measuring the voltage-dividing ratio of voltage-equaling capacitors used in the spark gap of a series capacitor compensation device of the present invention, and the series capacitor compensation device includes at least two spark gap branches and at least two capacitors branch, each spark gap branch includes at least one spark gap, each capacitor branch includes at least one capacitor, wherein the first spark gap branch and the first capacitor branch are connected in parallel to form the first spark capacitor branch, and the second spark gap branch The gap branch and the second capacitor branch are connected in parallel to form a second spark capacitor branch, one end of the first spark capacitor branch is a low voltage end, and the other end of the first spark capacitor branch is connected in series with one end of the second spark capacitor branch, The other end of the second spark capacitor branch is the high voltage end, and the measurement methods include:

Step S101, disconnecting the electrical connection between the first capacitor branch and the low voltage end and/or disconnecting the electrical connection between the second capacitor branch and the high voltage end;

Step S102, applying the same test voltage to both ends of the first capacitor branch and the second capacitor branch, and the frequency of the test voltage is greater than or equal to 500 Hz;

Step S103, measuring the current of the first capacitor branch to obtain the current of the first capacitor branch, and measuring the current of the second capacitor branch to obtain the current of the second capacitor branch;

Step S104, using the inverse ratio of the current ratio of the first capacitor branch current to the second capacitor branch current as the voltage division ratio of the first capacitor branch and the second capacitor branch.

According to the basic principle of the circuit, the capacitive reactance of the capacitor is inversely proportional to its frequency. Under the same test current, after increasing the frequency, the voltage applied to both ends of the capacitor decreases in inverse proportion according to Ohm's law; the same voltage is applied to two capacitors in series, through The current is the same, the voltage across the capacitor is inversely proportional to its capacitance value, and the same voltage is applied between two parallel capacitors, the passing current is proportional to the capacitance value of the branch, the voltage division ratio of the two series capacitors is the same as the change The current ratio after parallel connection is inversely proportional.

In this embodiment, after step S101 and step S102 are executed, the first capacitor branch and the second capacitor branch are connected in parallel, and the schematic circuit diagram is shown in FIG. 5 . The equivalent capacitance of the first capacitance branch and the equivalent capacitance of the second capacitance branch are respectively regarded as CA and CB, and a high-frequency voltage source is applied to both ends of the first capacitance branch and the two ends of the second capacitance branch at the same time, At the same time, the currents I1 and I2 flowing through the first capacitor branch and the second capacitor branch are collected, and the inverse ratio of the ratio of I1 to I2 is calculated to obtain the voltage division ratio between the equalizing capacitors C1 and C2.

Wherein, in step S101, disconnect the electrical connection between the first capacitor branch and the low voltage end and/or disconnect the electrical connection between the second capacitor branch and the high voltage end, since the first spark gap branch and the first capacitor branch are connected in parallel to form the first A spark capacitor branch, the second spark gap branch and the second capacitor branch are connected in parallel to form a second spark capacitor branch, one end of the first spark capacitor branch is a low voltage end, and the other end of the second spark capacitor branch is a high voltage end. Therefore, whether it is to disconnect the electrical connection between the first capacitor branch and the low-voltage terminal, or to disconnect the electrical connection between the second capacitor branch and the high-voltage terminal, or to disconnect the electrical connection between the first capacitor branch and the low-voltage terminal and to disconnect the second capacitor The electrical connection between the branch and the high-voltage end can realize the disconnection of the first capacitor branch and the second capacitor branch from the original circuit. At this time, a high-frequency voltage source is applied to both ends of the two capacitor branches respectively, then It is equivalent to applying a high-frequency voltage source to both ends of the capacitor branch after being connected in parallel with the two capacitor branches. Therefore, it is equivalent to the circuit schematic diagram in FIG. 5 .

In one of the embodiments, the frequency of the test voltage is greater than or equal to 500 Hz.

In one of the embodiments, the first spark gap branch includes a first sealed spark gap, the second spark gap branch includes a second sealed spark gap, the first capacitor branch includes a first capacitor, and The second capacitor branch includes a second capacitor.

In one of the embodiments, a current testing device is used to measure the first capacitor branch current and the second capacitor branch current.

Preferably, the current testing device is a current testing instrument, and the frequency of the testing voltage is greater than or equal to 500 Hz and less than or equal to 1500 Hz.

The principle of determining the frequency of the high-frequency voltage source is: to meet the test voltage below the safe voltage of 50V, in order to improve the test accuracy, the test current reaches (10-20) times the working current flowing through the voltage equalizing capacitor before the spark gap is triggered, and under the specified accuracy The test frequency range of the current test instrument (for example, the frequency of ordinary multimeters is mostly below 1500Hz, and the test frequency of high-precision multimeters can reach above 10kHz), and the frequency should not be too high to ensure the stability of the test power supply and not affect the surrounding electronic equipment According to the normal work of most series compensation engineering parameters, the frequency can be selected (500-1500) Hz.

A voltage source of 40V/1000Hz was once applied to both ends of the first capacitor branch and the second capacitor branch. The measured currents were 739μA and 754μA, and the voltage equalization ratio was 1.02. The consistency of the test data was good, and the test effect was obvious.

In one of the embodiments, the first spark gap branch includes a first main spark gap, the second spark gap branch includes a second main spark gap, and the first capacitor branch includes a first capacitor and a second capacitor. Two capacitors, the second capacitor branch includes a third capacitor and a fourth capacitor.

In this embodiment, the sealing spark gap part is removed in Fig. 2 .

In one of the embodiments, the series capacitor compensation device further includes a first sealed spark gap branch and a second sealed spark gap branch, the first sealed spark gap branch includes a first sealed spark gap, and the first sealed spark gap branch The two sealed spark gap branches include a second sealed spark gap, the first capacitor is connected in parallel with the first sealed spark gap branch to form a first capacitor sealed spark gap branch, and the second capacitor is connected to the second sealed spark gap branch. The sealed spark gap branches are connected in parallel to form a second capacitive sealed spark gap branch, and the first capacitive sealed spark gap branch is connected in series with the second capacitive sealed spark gap branch.

The schematic circuit diagram of this embodiment is shown in FIG. 2 .

The method for measuring the voltage-dividing ratio of the equalizing capacitor for the spark gap of the series capacitor compensation device also includes:

Applying the same test voltage to both ends of the first capacitor and the second capacitor;

measuring the current of the first capacitor to obtain the first capacitor current, and measuring the current of the second capacitor to obtain the second capacitor current;

The inverse ratio of the current ratio of the first capacitor current to the second capacitor current is used as the voltage division ratio of the first capacitor and the second capacitor.

During the test, it is only necessary to untie the electrical connection between the capacitor C1 and the low-voltage end of the spark gap, regard C1 and C2 as CA and CB respectively, apply a high-frequency voltage source T to both ends of the capacitor, and use the current tester A1 and current tester at the same time The instrument A2 collects the currents I1 and I2 flowing through the capacitors respectively, and calculates the ratio of I1 and I2 to obtain the voltage division ratio between the equalizing capacitors C1 and C2. Considering C1 in series with C2 and C3 in series with C4 as CA and CB respectively, the voltage division ratio of the two main gaps in series can be obtained in the same way. A voltmeter can also be connected in parallel to test the voltage U across the capacitor, and a single capacitance value can be tested when necessary.

In one of the embodiments, a current testing device is used to measure the first capacitor current and the second capacitor current.

Preferably, the current testing device is a current testing instrument, and the frequency of the testing voltage is greater than or equal to 500 Hz and less than or equal to 1500 Hz.

In one embodiment, the test voltage is less than or equal to 50 volts. Due to the method of increasing the test frequency, the test voltage can be reduced to below the safe voltage 50V under the condition of meeting the test current requirements, which improves the test safety and has a strong ability to resist power frequency interference.

In the actual test of the existing technology, when the power frequency voltage source is used to test the capacitance value one by one, the test voltage is high, and it is easily affected by the power frequency induction source on the series compensation platform. Higher safety isolation measures need to be taken. The entire test process Review, time-consuming, poor test accuracy. If the method of increasing the frequency of the voltage source and the shunt ratio of the test capacitor branch is used, the voltage should be low, no isolation is required during the test, and it is not subject to power frequency interference, the accuracy of the current test is high, the number of tests is reduced, and the entire test process is safe. , Simple and fast.

The testing method of the invention can reduce the testing voltage, improve the testing precision and efficiency, and has strong anti-interference performance at the same time.

The method of the invention has been verified in the Mabai series compensation project. The traditional method takes 4 hours to test, but only 1 hour after the method is adopted, and the test accuracy is greatly improved.

The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. A method for measuring the voltage-equaling capacitor voltage-dividing ratio of a series capacitor compensation device spark gap, comprising a series capacitor compensation device, said series capacitor compensation device comprising at least two spark gap branches and at least two capacitance branches, each Each spark gap branch includes at least one spark gap, and each capacitor branch includes at least one capacitor, wherein the first spark gap branch is connected in parallel with the first capacitor branch to form a first spark capacitor branch, and the second spark gap branch is connected with the first capacitor branch. The second capacitor branch is connected in parallel to form the second spark capacitor branch. One end of the first spark capacitor branch is a low-voltage end, and the other end of the first spark capacitor branch is connected in series with one end of the second spark capacitor branch. The second spark capacitor The other end of the branch is a high-voltage end, and it is characterized in that the measurement method includes: Disconnecting the electrical connection of the first capacitor branch from the low voltage terminal and/or disconnecting the electrical connection of the second capacitor branch from the high voltage terminal; Applying the same test voltage to both ends of the first capacitor branch and the second capacitor branch, and the frequency of the test voltage is greater than or equal to 500 Hz; measuring the current of the first capacitor branch to obtain the first capacitor branch current, and measuring the current of the second capacitor branch to obtain the second capacitor branch current; The inverse ratio of the current ratio of the first capacitor branch current to the second capacitor branch current is used as the voltage division ratio between the first capacitor branch circuit and the second capacitor branch circuit. 2. The measuring method of the voltage-equaling capacitor voltage-dividing ratio of the series capacitor compensation device spark gap according to claim 1, is characterized in that, the first spark gap branch comprises a first sealed spark gap, and the second spark gap The gap branch includes a second sealed spark gap, the first capacitance branch includes a first capacitance, and the second capacitance branch includes a second capacitance. 3. according to the measuring method of the voltage-equaling capacitance voltage dividing ratio of the spark gap of the series capacitance compensating device described in any one of claim 1-2, it is characterized in that, adopt current measuring device to measure described first capacitance branch current and the first Two capacitor branch currents. 4. the measuring method of voltage-equaling capacitor voltage-dividing ratio of series capacitance compensating device spark gap according to claim 3 is characterized in that, described current measuring device is a current measuring instrument, and the frequency of described testing voltage is greater than or equal to 500 Hz and less than or equal to 1500 Hz. 5. the method for measuring the voltage-equaling capacitor voltage-dividing ratio of the series capacitance compensation device spark gap according to claim 1, is characterized in that, the first spark gap branch comprises the first main spark gap, and the second spark gap The gap branch includes a second main spark gap, the first capacitor branch includes a first capacitor and a second capacitor, and the second capacitor branch includes a third capacitor and a fourth capacitor. 6. The measuring method of the voltage-equalizing capacitor voltage-dividing ratio of the series capacitor compensation device spark gap according to claim 5, characterized in that, the series capacitor compensation device also includes a first sealed spark gap branch and a second sealed spark gap branch, the first sealed spark gap branch includes a first sealed spark gap, the second sealed spark gap branch includes a second sealed spark gap, and the first capacitor is connected to the first sealed spark gap branch The circuit is connected in parallel to form the first capacitor sealed spark gap branch, and the second capacitor is connected in parallel with the second sealed spark gap branch to form the second capacitor sealed spark gap branch, and the first capacitor sealed spark gap branch is connected to the second capacitor sealed spark gap branch. Capacitor-sealed spark gap branches are connected in series. 7. the method for measuring the voltage-dividing ratio of the equalizing capacitor for the spark gap of the series capacitor compensation device according to claim 6, is characterized in that, also includes: Applying the same test voltage to both ends of the first capacitor and the second capacitor; measuring the current of the first capacitor to obtain the first capacitor current, and measuring the current of the second capacitor to obtain the second capacitor current; The inverse ratio of the current ratio of the first capacitor current to the second capacitor current is used as the voltage division ratio of the first capacitor and the second capacitor. 8. according to the measuring method of voltage-equaling capacitor voltage-dividing ratio of the spark gap of the series capacitance compensating device described in any one in claim 5-7, it is characterized in that, adopt current measuring device to measure described first capacitor current and the second capacitor current. 9. the method for measuring the voltage-equaling capacitor voltage-dividing ratio of the series capacitor compensation device spark gap according to claim 8, is characterized in that, the current test device is a current test instrument, and the frequency of the test voltage is greater than or equal to 500 Hz and less than or equal to 1500 Hz. 10. The method for measuring the voltage dividing ratio of the equalizing capacitor for the spark gap of the series capacitor compensation device according to claim 1, wherein the test voltage is less than or equal to 50 volts.