阅读说明：本技术 一种高压互感器群运行状态实时采集系统 (Real-time acquisition system for running state of high-voltage transformer group ) 是由 明东岳 鄢烈奇 唐登平 李俊 姚鹏 石洪 李帆 刘莉 荣先金 王�华 郭正 陈 于 2020-11-27 设计创作，主要内容包括：本发明提出了一种高压互感器群运行状态实时采集系统,基于高压互感器二次侧电压和泄露电流得出高压互感器的介质损耗,并且将压强、湿度、温度数据与基于二次侧电压和泄露电流分析出的介质损耗进行互相验证,增强了本系统对故障监测的可靠性；采用微电流传感器检测设备末端的泄露电流的方法相比于传统的超声波局部放电检测方法,其抗干扰能力更强,可以将有用信号从噪声中提取出来,减少系统检测的误差。(The invention provides a real-time acquisition system for the running state of a high-voltage transformer group, which is characterized in that the dielectric loss of the high-voltage transformer is obtained based on the secondary side voltage and the leakage current of the high-voltage transformer, and the pressure, humidity and temperature data and the dielectric loss analyzed based on the secondary side voltage and the leakage current are mutually verified, so that the reliability of the system for fault monitoring is enhanced; compared with the traditional ultrasonic partial discharge detection method, the method for detecting the leakage current at the tail end of the equipment by adopting the micro-current sensor has stronger anti-interference capability, can extract useful signals from noise, and reduces the detection error of a system.)

1. The utility model provides a real-time collection system of operating condition of high-voltage transformer crowd, its includes a plurality of high-voltage transformer, a plurality of detection channel and treater, and a plurality of detection channel detects a plurality of high-voltage transformer secondary side voltage and electric current one-to-one to give the treater with the testing result, its characterized in that: the detection channel comprises a secondary side voltage conditioning circuit and a leakage current conditioning circuit;

the secondary side voltage conditioning circuit detects the secondary side output voltage of the high-voltage transformer, conditions the detected analog quantity and inputs the conditioned analog quantity to a first digital input end of the processor;

the leakage current conditioning circuit detects leakage current of the high-voltage transformer, conditions the detected analog quantity and inputs the conditioned analog quantity to a second digital input end of the processor;

and the processor receives the digital signals output by the secondary side voltage conditioning circuit and the leakage current conditioning circuit and calculates the phase angle difference and the dielectric loss tangent value of the two signals.

2. The system for real-time acquisition of the operating state of the high-voltage transformer group as claimed in claim 1, wherein: the leakage current conditioning circuit comprises a current sensor, a first integrator, a high-pass filter, a phase correction circuit, a second integrator, a program-controlled power amplifier and a first A/D converter;

the primary side of the current sensor collects leakage current of a high-voltage transformer, the secondary side of the current sensor outputs a voltage signal to a first integrator, the first integrator performs integral amplification on the voltage signal, the amplified signal is input to a high-pass filter, the high-pass filter filters a direct current component in the input signal, the filtered signal is output to a phase correction circuit, the phase correction circuit adjusts the phase angle of the input signal within a preset range to enable the phase angle to be consistent with the phase of the output signal voltage and the primary side voltage of the current sensor, the phase correction circuit inputs the voltage signal with consistent phase to a second integration circuit, the second integration circuit eliminates the influence of power grid frequency fluctuation on the collection precision of the current sensor, the second integrator outputs the voltage signal to a program-controlled power amplifier, the program-controlled power amplifier changes signal gain, and inputs the gained voltage signal to a first A/D converter, the input voltage signal is converted into a discrete digital signal by the first A/D converter and is input to a first digital input end of the processor.

3. The system for real-time acquisition of the operating state of the high-voltage transformer group as claimed in claim 2, wherein: the secondary side voltage conditioning circuit comprises a capacitance voltage division circuit, a voltage follower, a non-inverting amplifier, a zero setting circuit and a second A/D converter;

the capacitance voltage division circuit divides the secondary side output voltage of the high-voltage transformer and outputs a divided voltage signal, the voltage signal is subjected to impedance matching through the voltage follower and then is input to the in-phase input end of the in-phase amplifier, the zero setting circuit is electrically connected with the reverse phase input end of the in-phase amplifier, the output end of the in-phase amplifier is electrically connected with the analog input end of the second A/D converter, and the digital output end of the second A/D converter is electrically connected with the second digital input end of the processor.

4. The system for real-time acquisition of the operating state of the high-voltage transformer group as claimed in claim 3, wherein: the capacitance voltage-dividing circuit includes: a capacitor C1, an adjustable capacitor C2, a capacitor C3, resistors R8-R10, a potentiometer RP3, a gas discharge tube TV1 and a bidirectional transient diode D2;

one end of the capacitor C3 inputs a secondary voltage signal of a high-voltage transformer, the other end of the capacitor C3 is electrically connected with one end of the capacitor C1 through a potentiometer RP3, the other end of the capacitor C1 is electrically connected with an input end of a voltage follower, the gas discharge tube TV1 is connected in parallel with two ends of the capacitor C1, the adjustable capacitor C2 is connected in parallel with two ends of the capacitor C1, the resistor R10 is connected in parallel with two ends of the adjustable capacitor C2, one end of the resistor R8 is electrically connected with one end of the capacitor C1, the other end of the resistor R8 is electrically connected with the other end of the capacitor C1 through the resistor R9, and the bidirectional transient diode D2 is connected in parallel with two ends of.

5. The system for real-time acquisition of the operating state of the high-voltage transformer group as claimed in claim 3, wherein: the detection channel also comprises a GPS receiving module;

the GPS receiving module receives an external GPS time service signal and outputs a PPS second pulse signal and a UART time service positioning signal to the processor, the processor captures the PPS second pulse signal and outputs the PPS second pulse signal to the first A/D converter and the second A/D converter through the I/O port of the processor, and synchronous sampling of the first A/D converter and the second A/D converter is achieved.

6. The system for real-time acquisition of the operating state of the high-voltage transformer group as claimed in claim 1, wherein: the detection channel also comprises a temperature detection module, a humidity detection module and a pressure detection module;

the temperature detection module detects a temperature value of the high-voltage transformer and sends the temperature value to the processor;

the humidity detection module detects a humidity value of the environment where the high-voltage transformer is located and sends the humidity value to the processor;

the pressure intensity detection module detects the pressure intensity change of the high-voltage transformer and sends the pressure intensity change value to the processor;

and the processor substitutes the acquired pressure, humidity and temperature data into a preset mathematical model, calculates the density and water content of the gas and judges the insulation performance of the high-voltage transformer.

Technical Field

The invention relates to the technical field of high-voltage transformer group detection, in particular to a real-time acquisition system for the running state of a high-voltage transformer group.

Background

The high-voltage transformer group is used for measuring the large current and the high voltage of a power system and provides the most basic and important measurement data for a power grid. As an important metering and protecting device in an electric power system, a Capacitor Voltage Transformer (CVT) has a direct relationship with the stability of grid operation and the accuracy of electric energy metering in safe and stable operation.

At present, a main method for detecting the state of the CVT is a power failure maintenance mode, the power supply is inevitably stopped in the mode, the workload is large, the maintenance period is long, the voltage applied in the test is not the high voltage born by the daily operation of the electrical equipment, the CVT state cannot be really judged, and the maintenance resources cannot be reasonably configured. Therefore, in order to solve the above problems, the invention provides a system for acquiring the running state of a high-voltage transformer group in real time, which can accurately track and grasp the running errors of the transformer group in running, acquire and record the running results of the transformer group in real time, and provide an accurate data base for the evaluation of the error state of the transformer.

Disclosure of Invention

In view of this, the invention provides a real-time acquisition system for the running state of a high-voltage transformer group, which can accurately track and master the running error of the transformer group in operation, acquire and record the running result of the transformer group in real time, and provide an accurate data basis for the evaluation of the error state of the transformer.

The technical scheme of the invention is realized as follows: the invention provides a real-time acquisition system for the running state of a high-voltage transformer group, which comprises a plurality of high-voltage transformers, a plurality of detection channels and a processor, wherein the plurality of detection channels detect the secondary side voltages and currents of the plurality of high-voltage transformers one by one and send the detection results to the processor, and each detection channel comprises a secondary side voltage conditioning circuit and a leakage current conditioning circuit;

the secondary side voltage conditioning circuit detects the secondary side output voltage of the high-voltage transformer, conditions the detected analog quantity and inputs the conditioned analog quantity to a first digital input end of the processor;

the leakage current conditioning circuit detects the leakage current of the high-voltage transformer, conditions the signal of the detected analog quantity and inputs the conditioned signal to a second digital input end of the processor;

and the processor receives the digital signals output by the secondary side voltage conditioning circuit and the leakage current conditioning circuit and calculates the phase angle difference and the dielectric loss tangent value of the two signals.

On the basis of the above technical solution, preferably, the leakage current conditioning circuit includes a current sensor, a first integrator, a high-pass filter, a phase correction circuit, a second integrator, a program-controlled power amplifier, and a first a/D converter;

the primary side of a current sensor collects leakage current of a high-voltage mutual inductor, the secondary side of the current sensor outputs a voltage signal to a first integrator, the first integrator performs integral amplification on the voltage signal, the amplified signal is input to a high-pass filter, the high-pass filter filters a direct current component in the input signal, the filtered signal is output to a phase correction circuit, the phase correction circuit adjusts the phase angle of the input signal within a preset range to enable the phase angle to be consistent with the phase of the output signal voltage and the primary side voltage of the current sensor, the phase correction circuit inputs the voltage signal with consistent phase to a second integration circuit, the second integration circuit eliminates the influence of power grid frequency fluctuation on the collection precision of the current sensor, the second integrator outputs the voltage signal to a program-controlled power amplifier, the program-controlled power amplifier changes signal gain, and inputs the gained voltage signal to a first A/D converter, the input voltage signal is converted into a discrete digital signal by the first A/D converter and is input to a first digital input end of the processor.

Further preferably, the secondary side voltage conditioning circuit comprises a capacitance voltage division circuit, a voltage follower, a non-inverting amplifier, a zero setting circuit and a second A/D converter;

the capacitance voltage division circuit divides the secondary side output voltage of the high-voltage transformer, outputs a divided voltage signal, the voltage signal is subjected to impedance matching through the voltage follower and then is input to the in-phase input end of the in-phase amplifier, the zero setting circuit is electrically connected with the reverse phase input end of the in-phase amplifier, the output end of the in-phase amplifier is electrically connected with the analog input end of the second A/D converter, and the digital output end of the second A/D converter is electrically connected with the second digital input end of the processor.

Further preferably, the capacitance voltage-dividing circuit includes: a capacitor C1, an adjustable capacitor C2, a capacitor C3, resistors R8-R10, a potentiometer RP3, a gas discharge tube TV1 and a bidirectional transient diode D2;

one end of a capacitor C3 inputs a secondary voltage signal of a high-voltage transformer, the other end of the capacitor C3 is electrically connected with one end of a capacitor C1 through a potentiometer RP3, the other end of the capacitor C1 is electrically connected with an input end of a voltage follower, a gas discharge tube TV1 is connected in parallel with two ends of the capacitor C1, an adjustable capacitor C2 is connected in parallel with two ends of a capacitor C1, a resistor R10 is connected in parallel with two ends of an adjustable capacitor C2, one end of a resistor R8 is electrically connected with one end of a capacitor C1, the other end of a resistor R8 is electrically connected with the other end of a capacitor C1 through a resistor R9, and a bidirectional transient diode D2 is connected in parallel with two ends.

On the basis of the above technical solution, preferably, the detection channel further includes a GPS receiving module;

the GPS receiving module receives an external GPS time service signal and outputs a PPS second pulse signal and a UART time service positioning signal to the processor, and the processor captures the PPS second pulse signal and outputs the PPS second pulse signal to the first A/D converter and the second A/D converter through an I/O port of the processor, so that synchronous sampling of the first A/D converter and the second A/D converter is realized.

On the basis of the technical scheme, preferably, the detection channel further comprises a temperature detection module, a humidity detection module and a pressure detection module;

the temperature detection module detects the temperature value of the high-voltage transformer and sends the temperature value to the processor;

the humidity detection module detects a humidity value of the environment where the high-voltage transformer is located and sends the humidity value to the processor;

the pressure detection module detects the pressure change of the high-voltage transformer and sends the pressure change value to the processor;

and the processor substitutes the acquired pressure, humidity and temperature data into a preset mathematical model, calculates the density and water content of the gas and judges the insulating property of the high-voltage transformer.

Compared with the prior art, the real-time acquisition system for the running state of the high-voltage transformer group has the following beneficial effects:

(1) the dielectric loss of the high-voltage transformer is obtained based on the secondary side voltage and the leakage current of the high-voltage transformer, and the pressure, humidity and temperature data and the dielectric loss analyzed based on the secondary side voltage and the leakage current are mutually verified, so that the reliability of the system for fault monitoring is enhanced;

(2) compared with the traditional ultrasonic partial discharge detection method, the method for detecting the leakage current at the tail end of the equipment by adopting the micro-current sensor has stronger anti-interference capability, can extract useful signals from noise, and reduces the detection error of a system;

(3) the high-pass filter is arranged in the leakage current conditioning circuit, so that the direct current offset output of the first integrator and other chips caused by the self-reason of devices or the influence of external temperature can be eliminated, and the direct current offset can be effectively filtered;

(4) the first integrator and the phase correction circuit are arranged in the leakage current conditioning circuit, so that the phase of a voltage signal detected by a later stage is consistent with the phase of a primary side voltage of the high-voltage transformer, the digital signal processing precision of the processor is improved, and the error of a system is reduced;

(5) the leakage current conditioning circuit is internally provided with a first integrator, a phase correction circuit and a second integrator, after the output voltage of the first integrator is corrected by the phase correction circuit, the output voltage of the first integrator is consistent with the primary side phase of the high-voltage transformer, but the first integrator performs integration processing to enable a voltage variation coefficient to be related to the power grid frequency, the measurement accuracy of the high-voltage transformer is influenced by the power grid frequency fluctuation, and the second integrator is matched with the first integrator to eliminate the influence of the power grid frequency fluctuation on the detection accuracy of the high-voltage transformer;

(6) the capacitance voltage division circuit adopts a two-stage voltage division mode of capacitance voltage division and resistance voltage division, so that the manufacturing difficulty can be reduced, the influence of overvoltage on the secondary side voltage conditioning circuit can be reduced, and the effect of protecting the secondary side voltage conditioning circuit is achieved; meanwhile, the current and voltage in a sine form can be converted into complex numbers so as to be convenient for calculation, and the error of the system is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a structural diagram of a real-time acquisition system for the running state of a high-voltage transformer group according to the invention;

fig. 2 is a structural diagram of a secondary side voltage conditioning circuit and a leakage current conditioning circuit in a real-time acquisition system of the operating state of a high-voltage transformer group according to the invention;

fig. 3 is a circuit diagram of a secondary side voltage conditioning circuit in a real-time acquisition system of the operation state of a high-voltage transformer group according to the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

As shown in fig. 1, the system for acquiring the operation state of the high-voltage transformer group in real time of the invention includes a plurality of high-voltage transformers, a plurality of detection channels and a processor.

The plurality of high-voltage transformers form a high-voltage transformer group, and the acquisition system monitors the running state real-time data of the high-voltage transformer group.

The detection channels are used for detecting the real-time running state data of each high-voltage transformer group in the high-voltage transformer group, one detection channel is used for detecting the secondary side voltage and current of one high-voltage transformer, and the detection result is sent to the processor. In this embodiment, the structures and principles of the plurality of detection channels are the same, and therefore, only one of the detection channels is described herein. Preferably, the detection channel comprises a secondary side voltage conditioning circuit, a leakage current conditioning circuit, a temperature detection module, a humidity detection module and a pressure detection module.

And the secondary side voltage conditioning circuit is used for detecting the secondary side output voltage of the high-voltage transformer, conditioning the detected analog quantity and inputting the conditioned analog quantity to the first digital input end of the processor. The leakage current conditioning circuit detects leakage current of the high-voltage transformer, conditions signals of the detected analog quantity and inputs the conditioned signals to the second digital input end of the processor.

The temperature detection module detects the temperature value of the high-voltage transformer and sends the temperature value to the processor.

The humidity detection module detects the humidity value of the environment where the high-voltage transformer is located and sends the humidity value to the processor.

The pressure intensity detection module detects the pressure intensity change of the high-voltage mutual inductor and sends the pressure intensity change value to the processor.

The processor receives digital signals output by the secondary side voltage conditioning circuit and the leakage current conditioning circuit, and calculates the phase angle difference and the dielectric loss tangent value of the two signals to obtain the dielectric loss of the high-voltage transformer; receiving data of collected pressure, humidity and temperature, substituting the collected pressure, humidity and temperature data into a preset mathematical model, calculating the density and water content of gas, and judging the insulation performance of the high-voltage transformer; the pressure, humidity and temperature data and the dielectric loss analyzed based on the secondary side voltage and the leakage current are mutually verified, so that the reliability of the system for fault monitoring is enhanced.

The working principle of the embodiment is as follows: the secondary side voltage conditioning circuit and the leakage current conditioning circuit are synchronously detected, and the detection result is sent to the processor, and the processor obtains the dielectric loss of the high-voltage transformer based on the secondary side voltage and the leakage current of the high-voltage transformer; meanwhile, the temperature detection module, the humidity detection module and the pressure detection module detect the pressure, humidity and temperature data of the high-voltage transformer in real time, and verify the acquired environmental data and the dielectric loss mutually to obtain the dielectric loss which is more in line with the reality.

The beneficial effect of this embodiment does: the dielectric loss of the high-voltage transformer is obtained based on the secondary side voltage and the leakage current of the high-voltage transformer, and the pressure, humidity and temperature data and the dielectric loss analyzed based on the secondary side voltage and the leakage current are mutually verified, so that the reliability of the system for monitoring faults is enhanced.

Example 2

The dielectric loss measurement of the high-voltage transformer belongs to the precise measurement of high voltage, micro current and small angle, has high requirement on the measurement method, and can accurately reflect the insulation state of equipment only by effectively reducing errors and measuring data. In the measurement, noise is an undesirable disturbing signal, which is white noise and low-frequency noise formed by limiting and affecting the sensitivity and fine noise of the measuring instrument, and these noises cannot be eliminated by means of shielding or the like. In order to reduce the effect of noise on the useful signal, a narrow band filter is often used to filter out the out-of-band noise to improve the signal-to-noise ratio of the signal. However, because the center frequency of a general filter is unstable, the bandwidth of the general filter is related to the center frequency, the Q value of the filter, and the like, the general filter cannot meet the requirement of higher noise filtering, and a large error exists, so that the measured data cannot accurately reflect the dielectric loss of the high-voltage transformer, therefore, in order to solve the above problems, in this embodiment, a micro-current sensor is used for detecting the leakage current at the tail end of the equipment, a bus end utilizes a capacitance voltage division principle to extract a secondary voltage signal, two paths of analog signals are converted into discrete digital signals by an a/D converter after being shaped, filtered, amplified and synchronously sampled, and then a processor utilizes a virtual instrument to obtain the phase angle difference and the dielectric loss tangent value of the two signals. The specific structure and principle are as follows:

and the leakage current conditioning circuit is used for detecting the leakage current of the high-voltage transformer, shaping, filtering, amplifying and synchronously sampling the acquired analog signals, converting the analog signals into digital signals, and sending the digital signals into the processor for processing. The traditional leakage current detection usually adopts ultrasonic partial discharge detection, but because the detected ultrasonic signals are very weak and various interference sources exist on the site, the signals are submerged in noise and larger errors exist. Therefore, in order to solve the above problem, in the present embodiment, the leakage current conditioning circuit detects the leakage current at the end of the high-voltage transformer by using the micro-current sensor, as shown in fig. 2, which includes a current sensor, a first integrator, a high-pass filter, a phase correction circuit, a second integrator, a programmable power amplifier, and a first a/D converter, which are connected in sequence.

And the current sensor is used for detecting the leakage current at the tail end of the high-voltage transformer. Preferably, the current sensor can be an electronic voltage transformer.

The first integrator has very weak output voltage due to the very small mutual inductance coefficient of the current sensor, and performs integral amplification on the sampling voltage of the first integrator in order to ensure that signals are not lost.

The high-pass filter may cause the first integrator and other chips to have dc offset output due to the device itself or the influence of the external temperature, and therefore, in order to eliminate the influence of the dc offset, the high-pass filter provided in this embodiment can effectively filter the dc offset. In this embodiment, the structure improvement of the high-pass filter is not involved, and the implementation can be realized by using the existing high-pass filter, which will not be described in detail herein.

The phase correction circuit, because the current sensor itself has a certain angular difference, makes the first integrator unable to completely implement 90 ° phase shift, its lag phase shift is always slightly greater than 90 °, reducing the detection accuracy of the system, therefore, in order to ensure the phase of the first integrator output voltage and the high voltage side voltage to be consistent, the phase correction circuit is provided in this embodiment, and the phase angle of the first integrator output voltage can be adjusted within the range of 0-10 °.

After the output voltage of the first integrator is corrected by the phase correction circuit, the output voltage of the first integrator is consistent with the primary side phase of the high-voltage transformer, but after the first integrator performs integration processing, the voltage variation coefficient is related to the power grid frequency, and the power grid frequency fluctuation can affect the measurement accuracy of the high-voltage transformer.

Since the leakage current amplitude of the programmable power amplifier varies with the tower type, the operating voltage, the weather, and the like, even differs by about 20 times, in order to stabilize the voltage of the analog input pin of the first a/D converter, the programmable power amplifier is provided in this embodiment, and the gain of the signal is dynamically changed before data conversion.

The working principle of the embodiment is as follows: the current sensor detects the leakage current at the tail end of the high-voltage mutual inductor, converts the leakage current into a voltage signal, outputs the voltage signal to the first integrator, the first integrator performs integral amplification on the voltage signal, inputs the amplified signal to the high-pass filter, the high-pass filter filters out the direct current component in the input signal, the filtered signal is output to the phase correction circuit, the phase correction circuit adjusts the phase angle of the input signal within a preset range to enable the phase angle to be consistent with the phase of the output signal voltage and the primary side voltage of the current sensor, the phase correction circuit inputs the voltage signal with consistent phase to the second integration circuit, the second integration circuit eliminates the influence of power grid frequency fluctuation on the acquisition precision of the current sensor, the second integrator outputs the voltage signal to the program-controlled power amplifier, the program-controlled power amplifier changes the signal gain and inputs the gained voltage signal to the first A/D converter, the input voltage signal is converted into a discrete digital signal by the first A/D converter and is input to a first digital input end of the processor.

The beneficial effect of this embodiment does: compared with the traditional ultrasonic partial discharge detection method, the method for detecting the leakage current at the tail end of the equipment by adopting the micro-current sensor has stronger anti-interference capability, can extract useful signals from noise, and reduces the detection error of a system;

the high-pass filter is arranged in the leakage current conditioning circuit, so that the direct current offset output of the first integrator and other chips caused by the self-reason of devices or the influence of external temperature can be eliminated, and the direct current offset can be effectively filtered;

the first integrator and the phase correction circuit are arranged in the leakage current conditioning circuit, so that the phase of a voltage signal detected by a later stage is consistent with the phase of a primary side voltage of the high-voltage transformer, the digital signal processing precision of the processor is improved, and the error of a system is reduced;

a first integrator, a phase correction circuit and a second integrator are arranged in a leakage current conditioning circuit, after the output voltage of the first integrator is corrected by the phase correction circuit, the output voltage of the first integrator is consistent with the primary side phase of the high-voltage transformer, but the first integrator performs integration processing to enable a voltage change coefficient to be related to the power grid frequency, the measurement accuracy of the high-voltage transformer is affected by the power grid frequency fluctuation, and the second integrator is matched with the first integrator to eliminate the influence of the power grid frequency fluctuation on the detection accuracy of the high-voltage transformer.

Example 3

On the basis of embodiment 1, in order to reduce the error of the system, this embodiment provides a structure and an operating principle for reducing the detection error of the secondary-side voltage conditioning circuit, and specifically, as shown in fig. 2, the secondary-side voltage conditioning circuit includes a capacitor voltage dividing circuit, a voltage follower, a non-inverting amplifier, a zeroing circuit, and a second a/D converter.

And the capacitance voltage division circuit extracts a secondary voltage signal of the high-voltage transformer. Preferably, as shown in fig. 3, the capacitive voltage divider circuit includes a capacitor C1, an adjustable capacitor C2, a capacitor C3, resistors R8-R10, a potentiometer RP3, a gas discharge tube TV1, and a bi-directional transient diode D2; specifically, a secondary voltage signal of a high-voltage transformer is input to one end of a capacitor C3, the other end of the capacitor C3 is electrically connected with one end of a capacitor C1 through a potentiometer RP3, the other end of the capacitor C1 is electrically connected with an input end of a voltage follower, a gas discharge tube TV1 is connected in parallel to two ends of the capacitor C1, an adjustable capacitor C2 is connected in parallel to two ends of a capacitor C1, a resistor R10 is connected in parallel to two ends of the adjustable capacitor C2, one end of the resistor R8 is electrically connected with one end of a capacitor C1, the other end of the resistor R8 is electrically connected with the other end of a capacitor C1 through a resistor R9, and a bidirectional transient diode D2 is connected in parallel to two. The capacitor C3 is a high-voltage standard capacitor, and the capacitance value is in the interval of 10-20 pF; the capacitance C1 is a mica capacitor, the capacitance is in the order of tens of nF, and 10nF can be selected; the capacitor C3 and the potentiometer RP3 form a capacitor voltage division mode, the capacitor C1 and the resistors R8-R10 form a resistor voltage division mode, and the capacitor voltage division mode and the resistor voltage division mode are adopted, so that the manufacturing difficulty of the capacitor C1 can be reduced, the influence of overvoltage on the secondary side voltage conditioning circuit can be reduced, and the effect of protecting the secondary side voltage conditioning circuit is achieved; the magnitude of the proportion of the resistor RP3 and the occupied power frequency series impedance is the same as that of the parallel admittance proportion of the resistors R8-R10, and the sine current and voltage can be converted into complex numbers for convenient calculation; the potentiometer RP3 and the adjustable capacitor C2 are mounted and connected on the structure, so that the adjustment of the resistance and the capacitance can be met. In this embodiment, Vin represents the secondary voltage signal of the high-voltage transformer.

The voltage follower plays roles in isolation, impedance matching and improvement of the load carrying capacity. Belongs to the prior art and is not described in detail.

The in-phase amplifier amplifies a secondary voltage signal of a high-voltage transformer extracted by the capacitance voltage division circuit, belongs to the prior art, and is not described in detail herein.

The zero setting circuit eliminates the zero drift problem of the inverting input end of the non-inverting amplifier, belongs to the prior art, and is not described in detail herein. The circuit diagram can be selected from the circuit shown in fig. 3, wherein the resistor R5, the resistor R6, the resistor R2 and the potentiometer RP2 form a zero setting circuit.

The second a/D converter converts the analog signal output by the non-inverting amplifier into a digital signal, which belongs to the prior art and will not be described in detail herein. Where the analog input of the second a/D converter is denoted by a/D, as shown in fig. 3.

In order to realize synchronous sampling of the secondary side voltage conditioning circuit and the leakage current conditioning circuit, in this embodiment, a GPS receiving module is further provided, and receives an external GPS time signal and outputs a PPS second pulse signal and a UART time positioning signal to a processor, and the processor captures the PPS second pulse signal and outputs the PPS second pulse signal to the first a/D converter and the second a/D converter through an I/O port of the processor, so that synchronous sampling of the first a/D converter and the second a/D converter is realized. The GPS receiving module can be implemented by using the prior art, and will not be described herein again.

The working principle of the embodiment is as follows: the capacitance voltage division circuit divides the secondary side output voltage of the high-voltage transformer, a divided voltage signal is output, the voltage signal is subjected to impedance matching through the voltage follower and then is input to the in-phase input end of the in-phase amplifier, the in-phase amplifier amplifies the voltage, meanwhile, the zero drift of the in-phase amplifier is eliminated through the zero setting circuit, the in-phase amplifier outputs the amplified voltage signal to the second A/D converter, the second A/D converter converts the voltage signal into a digital signal and outputs the digital signal to the processor, the processor takes the voltage extracted by secondary measurement of the high-voltage transformer as a standard, the tangent value of an included angle between the calculated and measured leakage currents is calculated, and the dielectric loss is obtained.

The beneficial effect of this embodiment does: the capacitance voltage division circuit adopts a two-stage voltage division mode of capacitance voltage division and resistance voltage division, so that the manufacturing difficulty of the capacitor C1 can be reduced, the influence of overvoltage on the secondary side voltage conditioning circuit can be reduced, and the effect of protecting the secondary side voltage conditioning circuit is achieved; meanwhile, the current and voltage in a sine form can be converted into complex numbers so as to be convenient for calculation, and the error of the system is reduced.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.