阅读说明：本技术 一种高压环境下的电容容值测量方法 (Capacitance value measuring method under high-voltage environment ) 是由 何鹏 白利兵 周权 张旭 张�杰 程玉华 于 2021-10-25 设计创作，主要内容包括：本发明提供一种高压环境下的电容容值测量方法,属于电容测量技术领域,先获取待测电容所处高压环境的参数,构建由高压直流偏置单元、高频变压单元和与待测电容并联的放电单元串联成回路的电压电流测量电路；以可调电容器为待测电容接入电压电流测量电路,获取参考工作曲线；接入待测电容后断开放电单元,启动高压直流稳压电源至高电压输出,启动高频变压单元测量原边的电压和电流,关闭高压直流稳压电源和高频变压单元,接通放电单元；根据待测电容对应电压和电流在参考工作曲线中查找可选电容值,作为待测电容在高压环境下的电容值。本发明保证了获取参考工作曲线和测量待测电容时电路的工作状态一致,实现高压环境下高精度的电容容值测量。(The invention provides a capacitance value measuring method under a high-voltage environment, which belongs to the technical field of capacitance measurement, and comprises the steps of firstly obtaining parameters of the high-voltage environment where a capacitor to be measured is located, and constructing a voltage and current measuring circuit of a loop formed by connecting a high-voltage direct-current bias unit, a high-frequency voltage transformation unit and a discharge unit connected with the capacitor to be measured in parallel in series; accessing a voltage and current measuring circuit by taking an adjustable capacitor as a capacitor to be measured to obtain a reference working curve; switching off a discharge unit after a capacitor to be tested is connected, starting a high-voltage direct-current voltage-stabilized power supply to high-voltage output, starting a high-frequency voltage transformation unit to measure the voltage and current of a primary side, switching off the high-voltage direct-current voltage-stabilized power supply and the high-frequency voltage transformation unit, and switching on the discharge unit; and searching for an optional capacitance value in the reference working curve according to the voltage and the current corresponding to the capacitor to be detected, wherein the optional capacitance value is used as the capacitance value of the capacitor to be detected in the high-voltage environment. The invention ensures that the working state of the circuit is consistent when the reference working curve is obtained and the capacitance to be measured is measured, and realizes the high-precision capacitance value measurement of the capacitor under the high-voltage environment.)

1. A capacitance value measuring method under a high-voltage environment is characterized by comprising the following steps:

s1: obtaining a capacitance C to be measured_XParameters of the high-voltage environment comprise direct-current bias voltage, voltage amplitude and voltage frequency;

s2: constructing a voltage and current measuring circuit of a loop formed by connecting a high-voltage direct-current bias unit, a high-frequency voltage transformation unit and a discharge unit in series, and connecting a capacitor C to be measured_XConnected in parallel with the discharge unit;

the high-voltage direct-current bias unit comprises a high-voltage direct-current voltage-stabilizing power supply, a resistor R and a capacitor C which are connected in series to form a loop, and the two ends of the capacitor C are used as connection points with a voltage and current measuring circuit and are used as the capacitance C to be measured_XProviding a bias voltage; the high-voltage direct-current stabilized power supply provides voltage according to the direct-current bias voltage;

the high-frequency voltage transformation unit is used as the capacitor C to be tested according to the voltage amplitude and the voltage frequency_XApplying an alternating voltage and measuring the voltage and current of the primary side;

the discharge unit is used for measuring the capacitance C_XCarrying out intermittent discharge;

s3: will be a tunable capacitor C_TAs the capacitor C to be measured_XThe method comprises the following specific processes of accessing a voltage and current measuring circuit to obtain a reference working curve:

s3.1: to measure the capacitance C_XRespectively as the adjustable capacitor C_TThe upper limit and the lower limit of the capacitance value of (C), N selectable capacitance values C are set_iI =1,2, …, N, wherein N ≧ 3;

s3.2: let sequence number i = 1;

s3.3: will be a tunable capacitor C_TIs set to a selectable capacitance value C_i；

S3.4: the discharge unit is disconnected, the high-voltage direct-current stabilized voltage power supply is started and adjusted to preset low-voltage output to the adjustable capacitorDevice C_TThe voltage at the two ends is not changed any more; then starting the high-frequency voltage transformation unit, and measuring the voltage V of the primary side after the voltage and current measurement circuit is stabilized_iAnd current I_i；

S3.5: turning off the high-voltage DC stabilized voltage power supply and the high-frequency voltage transformation unit, turning on the discharge unit, and adjusting the capacitance of the adjustable capacitor C_TDischarging;

s3.6: judging whether i < N, if yes, entering step S3.7; otherwise, entering step S3.8;

s3.7: let i = i +1, return to step S3.3;

s3.8: according to the adjustable capacitor C in a three-dimensional coordinate system_TN selectable capacitance values C_iCorresponding voltage V_iAnd current I_iDrawing to obtain a reference working curve;

s4: the capacitor C to be measured_XConnecting a voltage and current measuring circuit, disconnecting the discharge unit, starting the high-voltage direct-current stabilized voltage power supply, regulating the high-voltage direct-current stabilized voltage power supply to high-voltage output, and sending the high-voltage direct-current stabilized voltage power supply to the capacitor C to be measured_XThe voltage at the two ends is not changed any more; then starting the high-frequency voltage transformation unit, and measuring the voltage V 'and the current I' of the primary side after the voltage and current measurement circuit is stabilized; then the high-voltage direct-current voltage-stabilized power supply and the high-frequency voltage transformation unit are turned off, the discharge unit is turned on, and the capacitor C to be measured is subjected to voltage transformation_XDischarging;

s5: according to the capacitance C to be measured_XCorresponding voltage V 'and current I' are searched in a reference working curve for corresponding selectable capacitance values to be used as the capacitor C to be measured_XA capacitance value in a high-pressure environment.

2. The method according to claim 1, wherein the high frequency transforming unit comprises a voltmeter, and a high frequency power source, a high frequency transformer T and an ammeter connected in series to form a loop, and two ends of the high frequency transformer T are used as connection points with the voltage and current measuring circuit.

3. The method according to claim 2, wherein the resistor R and the capacitor C in the HVDC bias unit form a low-pass filter with cut-off frequencyRate f_CNot exceeding one tenth of the output frequency f of the high frequency power supply.

4. The method according to claim 1, wherein the capacitance value of the capacitor C is not lower than that of the capacitor C to be measured_X1000 times the capacitance value of (c).

5. The method according to claim 1, wherein the discharge unit comprises a switch K and a discharge resistor R connected in series_L。

6. The method for measuring capacitance and capacitance values in a high-voltage environment according to claim 1, wherein the value of the low voltage preset in S3.4 is determined according to the value of the adjustable capacitor C_TThe upper limit and the lower limit of the capacitance value are determined so as to ensure that the adjustable capacitor C is ensured after the high-voltage direct-current voltage-stabilized power supply is started_TOptional capacitance value C of_iAnd is not changed.

Technical Field

The invention belongs to the technical field of capacitance measurement, and particularly relates to a capacitance value measurement method in a high-voltage environment.

Background

The high-voltage capacitor has wide application in ignition, X-ray, large-scale transformer substation and other equipment. In a high-voltage environment of 1.5-20 kV, the capacitance value of the capacitor can change. Due to the lack of an effective capacitance value measuring method in a high-voltage environment, the capacitance value is often used as a constant in the current circuit design, so that circuit parameter deviation is large and calibration is difficult. The conventional capacitance value measuring instrument mainly performs measurement in a low-voltage environment, such as an LCR tester, a capacitance bridge tester, and the like. Although the LCR tester can guarantee higher measurement accuracy, the equipment is large in size and complex in operation, the maximum voltage which can be provided by measurement is 2V, and the test requirement of thousands of volts in a high-voltage environment cannot be met. The capacitance bridge tester is fast and convenient to apply, stable in performance and high in measurement accuracy, but the maximum voltage which can be provided by measurement is 26V, and the actual test requirements cannot be met.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a capacitance value measuring method in a high-voltage environment, and a reference working curve is drawn by constructing a voltage and current measuring circuit of a capacitor, so that the capacitance value measurement in the high-voltage environment is realized.

The specific technical scheme of the invention is as follows:

a capacitance value measuring method under a high-voltage environment is characterized by comprising the following steps:

s1: obtaining a capacitance C to be measured_XParameters of the high-voltage environment comprise direct-current bias voltage, voltage amplitude and voltage frequency;

s2: constructing a voltage and current measuring circuit of a loop formed by connecting a high-voltage direct-current bias unit, a high-frequency voltage transformation unit and a discharge unit in series, and connecting a capacitor C to be measured_XConnected in parallel with the discharge unit for measuring the capacitance C to be measured_XThe voltage and the current of the primary side of the corresponding high-frequency transformation unit;

the high-voltage direct-current bias unit comprises a high-voltage direct-current voltage-stabilized power supply, a resistor R and a capacitor C which are connected in series to form a loop,and the two ends of the capacitor C are taken as connection points with the voltage and current measuring circuit and are used for measuring the capacitor C to be measured_XProviding a bias voltage; the high-voltage direct-current stabilized power supply provides voltage according to the direct-current bias voltage obtained in the step S1;

the high-frequency transformation unit is used as the capacitor C to be tested according to the voltage amplitude and the voltage frequency obtained by S1_XApplying an alternating voltage and measuring the voltage and current of the primary side;

the discharge unit is used for measuring the capacitance C_XCarrying out intermittent discharge;

s3: will be a tunable capacitor C_TAs the capacitor C to be measured_XThe method comprises the following specific processes of accessing a voltage and current measuring circuit to obtain a reference working curve:

s3.1: to measure the capacitance C_XRespectively as the adjustable capacitor C_TThe upper limit and the lower limit of the capacitance value of (C), N selectable capacitance values C are set_iI =1,2, …, N, wherein N ≧ 3;

s3.2: let sequence number i = 1;

s3.3: will be a tunable capacitor C_TIs set to a selectable capacitance value C_i；

S3.4: the discharge unit is disconnected, the high-voltage direct-current stabilized voltage power supply is started and adjusted to preset low-voltage output to the adjustable capacitor C_TThe voltage at the two ends is not changed any more; then starting the high-frequency voltage transformation unit, and measuring the voltage V of the primary side after the voltage and current measurement circuit is stabilized_iAnd current I_i；

S3.5: turning off the high-voltage DC stabilized voltage power supply and the high-frequency voltage transformation unit, turning on the discharge unit, and adjusting the capacitance of the adjustable capacitor C_TDischarging;

s3.6: judging whether i < N, if yes, entering step S3.7; otherwise, entering step S3.8;

s3.7: let i = i +1, return to step S3.3;

s3.8: according to the adjustable capacitor C in a three-dimensional coordinate system_TN selectable capacitance values C_iCorresponding voltage V_iAnd current I_iDrawing to obtain a reference working curve;

s4: the capacitor C to be measured_XAccess voltage current measurementThe measuring circuit is used for switching off the discharge unit, starting the high-voltage direct-current stabilized voltage power supply and regulating the high-voltage direct-current stabilized voltage power supply to high-voltage output to the capacitor C to be measured_XThe voltage at the two ends is not changed any more; then starting the high-frequency voltage transformation unit, and measuring the voltage V 'and the current I' of the primary side after the voltage and current measurement circuit is stabilized; then the high-voltage direct-current voltage-stabilized power supply and the high-frequency voltage transformation unit are turned off, the discharge unit is turned on, and the capacitor C to be measured is subjected to voltage transformation_XDischarging;

s5: according to the capacitance C to be measured_XThe corresponding voltage V 'and current I' are used to search the corresponding selectable capacitance value in the reference working curve obtained in step S3, and the value is used as the capacitor C to be measured_XA capacitance value in a high-pressure environment.

Further, the high-frequency transformation unit comprises a voltmeter, a high-frequency power supply, a high-frequency transformer T and an ammeter, wherein the high-frequency power supply, the high-frequency transformer T and the ammeter are connected in series to form a loop, the voltmeter and the ammeter are respectively used for measuring voltage and current of a primary side, and two ends of the high-frequency transformer T are used as connection points of the high-frequency transformer T and the voltage and current measurement circuit.

Further, the resistor R and the capacitor C in the high voltage DC bias unit form a low pass filter with a cut-off frequency f_CThe output frequency f of the high-frequency power supply in the high-frequency voltage transformation unit is not more than one tenth of the output frequency f of the high-frequency power supply in the high-frequency voltage transformation unit, so that the output of the high-frequency power supply is prevented from influencing the high-voltage direct-current stabilized power supply.

Further, the capacitance value of the capacitor C is not lower than that of the capacitor C to be measured_XThe capacitance value of the capacitor C is 1000 times, so that the capacitive reactance of the capacitor C is prevented from influencing the measurement result, and the measurement precision is improved.

Further, the value of the preset low voltage in S3.4 is determined according to the adjustable capacitor C_TThe upper limit and the lower limit of the capacitance value are determined so as to ensure that the adjustable capacitor C is ensured after the high-voltage direct-current voltage-stabilized power supply is started_TOptional capacitance value C of_iAnd is not changed.

Further, the discharge unit comprises a switch K and a discharge resistor R which are connected in series_L。

The invention has the beneficial effects that:

1. the invention provides a capacitance value measuring method under a high-voltage environment, which adopts a high-voltage direct-current stabilized voltage power supply as a capacitor C to be measured_XProviding working voltage to ensure the capacitor C to be tested_XThe working state of the device is consistent with the actual high-pressure environment; adopting a high-frequency transformer T as a capacitor C to be measured_XAlternating voltage disturbance is injected, high-voltage isolation is realized, and conditions are created for the use of a high-precision low-voltage measuring instrument;

2. in measuring the capacitance C to be measured_XAnd a tunable capacitor C_TWhen the voltage and the current are in the high-voltage direct-current stabilized voltage supply, the charging and discharging current in the loop is zero after the high-voltage direct-current stabilized voltage supply is started, so that the high-frequency transformer T (the working state of the high-frequency transformer T is mainly influenced by the current and the frequency) obtains a reference working curve and measures the capacitor C to be measured_XThe working states are consistent, so that the transmission of high-precision measurement reference is ensured;

3. preferably, the capacitance value of the capacitor C required by the invention is far greater than that of the capacitor C to be measured_XThe capacitance value of can effectively avoid electric capacity C to influence because of the capacitance value that high voltage environment leads to for electric capacity C's operating condition is similar unanimous under the low pressure environment when obtaining reference working curve under the high voltage environment, and high frequency transformer T's operating condition is not influenced by the voltage, and then guarantees electric capacity C that awaits measuring under the high voltage environment_XOperating conditions in the test circuit, and adjustable capacitors C in low-voltage environments_TThe working states in the test circuit are consistent, so that the accuracy of the capacitance value measurement result of the capacitor is improved.

Drawings

Fig. 1 is a flowchart of a capacitance value measuring method in a high-voltage environment according to embodiment 1 of the present invention;

fig. 2 is a structural diagram of a voltage-current measuring circuit according to embodiment 1 of the present invention;

fig. 3 is a specific structural diagram of a voltage-current measuring circuit according to embodiment 1 of the present invention;

fig. 4 is a flowchart of acquiring a reference working curve in embodiment 1 of the present invention;

fig. 5 is a reference operating curve obtained in example 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described with reference to the following embodiments and the accompanying drawings.

The following non-limiting examples are presented to enable those of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.

Example 1

The present embodiment provides a method for measuring a capacitance value of a capacitor in a high-voltage environment, where the process is shown in fig. 1, and the method includes the following steps:

s1: acquiring capacitor C to be measured by voltmeter and oscilloscope_XParameters of the high-voltage environment comprise direct-current bias voltage, voltage amplitude and voltage frequency;

s2: constructing a voltage and current measuring circuit which is shown in figure 2 and is formed by connecting a high-voltage direct-current bias unit, a high-frequency transformation unit and a discharge unit in series into a loop, and connecting a capacitor C to be measured_XConnected in parallel with the discharge unit for measuring the capacitance C to be measured_XThe voltage and the current of the primary side of the corresponding high-frequency transformation unit; in which, as shown in figure 3,

the high-voltage direct-current bias unit comprises a high-voltage direct-current voltage-stabilizing power supply, a resistor R and a capacitor C which are connected in series to form a loop, and two ends of the capacitor C are used as connection points with a voltage and current measuring circuit and are used for measuring the capacitance C to be measured_xProviding a bias voltage; the high-voltage direct-current stabilized power supply provides voltage according to the direct-current bias voltage obtained in the step S1;

the high-frequency transformation unit comprises a voltmeter, a high-frequency power supply, a high-frequency transformer T and an ammeter, wherein the high-frequency power supply, the high-frequency transformer T and the ammeter are connected in series to form a loop; the high-frequency voltage transformation unit is used as the capacitor C to be tested according to the voltage amplitude and the voltage frequency obtained by the S1_XApplying alternating voltage, and measuring the voltage and the current of a primary side through a voltmeter and an ammeter respectively;

the discharge unit comprises a switch K and a discharge resistor R which are connected in series_LAnd respectively with a switch K and a discharge resistor R_LThe other end of the voltage measuring circuit is a connection point with a voltage and current measuring circuit and is used for measuring the capacitance C to be measured_XCarrying out intermittent discharge;

wherein the high-voltage direct current bias unit provides at least one kilovolt; in a high voltage DC bias unitThe resistor R and the capacitor C form a low-pass filter with a cut-off frequency f_CThe value of = 1/(2 pi RC) is not more than one tenth of the output frequency f of the high-frequency power supply in the high-frequency voltage transformation unit, so that the output of the high-frequency power supply is prevented from influencing the high-voltage direct-current stabilized power supply; the capacitance value of the capacitor C is not lower than that of the capacitor C to be measured_XThe capacitance value of the capacitor C is 1000 times, so that the capacitive reactance of the capacitor C is prevented from influencing the measurement result, and the measurement precision is improved; on the premise of meeting the measurement precision, the relative positions of the current meter and the voltmeter are flexibly configured; the working state of the high-frequency transformer T is mainly influenced by current and frequency, and the high-frequency transformer T is used as a capacitor C to be measured_xAlternating voltage disturbance is injected to realize high-voltage isolation, so that the influence of a high-voltage loop on measuring circuits such as a high-frequency power supply, a current meter and a voltmeter is prevented, and conditions are created for the use of a high-precision low-voltage measuring instrument;

s3: will be a tunable capacitor C_TAs the capacitor C to be measured_XA voltage and current measuring circuit is connected to obtain a reference working curve, as shown in fig. 4, the specific process is as follows:

s3.1: to measure the capacitance C_XRespectively as the adjustable capacitor C_TThe upper limit and the lower limit of the capacitance value of (C), N selectable capacitance values C are set_iI =1,2, …, N, wherein N ≧ 3;

s3.2: let sequence number i = 1;

s3.3: will be a tunable capacitor C_TIs set to a selectable capacitance value C_i；

S3.4: the discharge unit is disconnected, the high-voltage direct-current stabilized voltage power supply is started and adjusted to preset low-voltage output to the adjustable capacitor C_TThe voltage at the two ends is not changed any more; then starting the high-frequency voltage transformation unit, and measuring the voltage V of the primary side after the voltage and current measurement circuit is stabilized_iAnd current I_i(ii) a Wherein the value of the preset low voltage is determined according to the adjustable capacitor C_TThe upper limit and the lower limit of the capacitance value are determined so as to ensure that the adjustable capacitor C is ensured after the high-voltage direct-current voltage-stabilized power supply is started_TOptional capacitance value C of_iThe change is not changed;

s3.5: turning off the high-voltage DC stabilized voltage power supply and the high-frequency voltage transformation unit, turning on the discharge unit, and adjustingCapacitor C_TDischarging;

s3.6: judging whether i < N, if yes, entering step S3.7; otherwise, entering step S3.8;

s3.7: let i = i +1, return to step S3.3;

s3.8: according to the adjustable capacitor C in a three-dimensional coordinate system_TN selectable capacitance values C_iCorresponding voltage V_iAnd current I_iDrawing to obtain a reference working curve, as shown in FIG. 5;

s4: obtaining a capacitance C to be measured_XCorresponding voltage current: the capacitor C to be measured_XConnecting a voltage and current measuring circuit, disconnecting the discharge unit, starting the high-voltage direct-current stabilized voltage power supply, regulating the high-voltage direct-current stabilized voltage power supply to high-voltage output, and sending the high-voltage direct-current stabilized voltage power supply to the capacitor C to be measured_XThe voltage at the two ends is not changed any more; then starting the high-frequency voltage transformation unit, and measuring the voltage V 'and the current I' of the primary side after the voltage and current measurement circuit is stabilized; then the high-voltage direct-current voltage-stabilized power supply and the high-frequency voltage transformation unit are turned off, the discharge unit is turned on, and the capacitor C to be measured is subjected to voltage transformation_XDischarging; wherein the high voltage is a dc bias voltage obtained according to S1;

s5: according to the capacitance C to be measured_XThe corresponding voltage V 'and current I' are used to search the corresponding selectable capacitance value in the reference working curve obtained in step S3, and the value is used as the capacitor C to be measured_XA capacitance value in a high-pressure environment.

Furthermore, the parameter configuration of the high-frequency transformers of the high-frequency transformation units in S3 and S4 is the same, so that the working states of the high-frequency transformers in the two processes are consistent, and the transmission of high-precision measurement references is ensured.

Further, in practical applications, equivalent impedance exists in circuit wires, components and the like in the voltage and current measuring circuit, and a small resistance can be necessarily added to meet the impedance requirement of the voltage and current measuring circuit.

Although illustrative embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, and various changes may be made apparent to those skilled in the art as long as they are within the spirit and scope of the present invention as defined and defined by the appended claims, and all matters of the invention which utilize the inventive concepts are protected.