Joint synchronous measurement system and method of space charge and high voltage frequency domain dielectric spectrum

Abstract

The present invention relates to the technical field of high-voltage frequency-domain dielectric spectroscopy, and in particular, provides a joint synchronous measurement system and method for space charge and high-voltage frequency-domain dielectric spectroscopy. The system includes a function generator, a terminal, an oscilloscope, a voltage amplifier, a nanosecond pulse source, a data acquisition card, a voltage divider, a space charge measurement electrode housing, an oil bath circulation device, a high-voltage electrode, a semi-conductive layer, a sample, a protective electrode, a current measurement electrode, a space charge measurement electrode, a piezoelectric film, a signal amplifier, and a current detection unit; the system solves the technical difficulties of joint measurement of space charge and alternating current, and directly measures the alternating current under nanosecond pulse high-voltage conditions, thereby avoiding the current information loss and measurement interference caused by time-sharing measurement, ensuring that the dielectric properties and space charge distribution of insulating materials can be accurately reflected under high-voltage electric fields, thereby improving the application accuracy and reliability of high-voltage FDS technology in insulation state assessment.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage frequency-domain dielectric spectroscopy, and in particular to a joint synchronous measurement system and method for space charge and high-voltage frequency-domain dielectric spectroscopy. Background Art

[0002] Frequency-domain Dielectric Spectroscopy (FDS) applies AC voltages of different frequencies to measure the corresponding current, and calculates the dielectric parameters in combination with the insulation size, and finally obtains the frequency-domain dielectric corresponding law. As a non-destructive testing technology, it can reveal rich insulation information, especially in the evaluation of the insulation status of power equipment. It has extremely high application value. However, the conventional FDS measurement voltage is low, and it is difficult to accurately reflect the dielectric properties of insulating materials under high operating electric fields. In addition, the measured current is weak and easily interfered by external factors. For this reason, high-voltage frequency-domain dielectric spectroscopy has gradually received attention in recent years, but the problem of spatial charge accumulation inside insulating materials under high electric field conditions cannot be ignored. The nanosecond pulse high voltage required by the PEA method will generate an ampere-level pulse current on the sample, which is much larger than the AC current. It will generate overvoltage in the circuit that detects the current and damage the instrument and equipment, which brings new challenges to the study of high-voltage frequency-domain dielectric response.

[0003] Most of the existing space charge measurement technologies use the electroacoustic pulse method (PEA method). The key to the joint measurement of space charge and frequency domain dielectric spectrum lies in the synchronous measurement technology of space charge and AC current. However, there has been no breakthrough in the joint measurement of space charge and AC current. Existing research can realize the joint measurement of space charge-DC current based on the electroacoustic pulse method. According to whether the space charge and current are measured simultaneously and whether the same position of the sample is measured, there are currently three technical solutions: ① Simultaneous and same area: the sampling resistor is placed on the high-voltage side of the DC circuit, and an inductor is introduced between the sampling resistor and the pulse circuit to isolate the DC circuit. This method can solve the above two problems, but the sampling resistor is placed on the high-voltage side, which requires high safety and reliability of the measurement circuit. ② Time-sharing and same area: glass with good sound transmission and insulation is added to the lower electrode and piezoelectric film to solve the piezoelectric effect problem, and the synchronous measurement of space charge and current at the same position of the same sample is realized, but there are problems such as the attenuation of sound waves in the glass and the mismatch of acoustic impedance at the interface of different materials, both of which will weaken the sensor receiving signal. ③ Time-sharing and partitioning: The PEA measurement electrode is improved to a "four-electrode" structure of a high-voltage upper electrode-space charge measurement electrode-current measurement electrode-protection electrode. The space charge and current measurement branches are in parallel, and the space charge and current are measured at different positions of the same sample. In actual measurements, the latter two methods are both controlled by switches. For example, the published patent documents CN105911326A, CN206671403U, and CN215641531U all control switches to independently measure space charge and relaxation current in time to solve the pulse current problem. However, this will lose current information during the space charge measurement process, and the switching speed and measurement and control system are required to be high during AC current measurement. The transient voltage formed by the rapid on and off of the switch will also affect the measurement, which makes this method unsuitable for AC conditions. Summary of the invention

[0004] In view of this, the present invention provides a system and method for the joint synchronous measurement of space charge and high-voltage frequency-domain dielectric spectrum, so as to solve the technical difficulties in the joint measurement of space charge and AC current, avoid the current information loss and measurement interference caused by time-sharing measurement, and ensure that the dielectric properties and space charge distribution of the insulating material can be accurately reflected under the high-voltage electric field, thereby improving the application accuracy and reliability of high-voltage FDS technology in insulation status assessment.

[0005] In a first aspect, the present invention provides a joint synchronous measurement system of space charge and high voltage frequency domain dielectric spectrum, the system comprising:

[0006] Function generator, terminal, oscilloscope, voltage amplifier, nanosecond pulse source, data acquisition card, voltage divider, space charge measurement electrode housing, oil bath circulation device, high voltage electrode, semi-conductive layer, sample, guard electrode, current measurement electrode, space charge measurement electrode, piezoelectric film, signal amplifier, current detection unit;

[0007] The function generator and the terminal, the voltage amplifier are connected with the nanosecond pulse source; the terminal is also connected with the oscilloscope and the data acquisition card; the oscilloscope is also connected with the voltage divider and the signal amplifier; the oil bath circulation device is arranged inside the outer shell of the space charge measurement electrode; the high voltage electrode, the semi-conductive layer and the sample are arranged in sequence at the bottom of the outer shell of the space charge measurement electrode; the protection electrode, the current measurement electrode and the space charge measurement electrode are arranged in parallel at the bottom of the sample; the current detection unit is connected with the data acquisition card and the current measurement electrode.

[0008] Optionally, the function generator is used to generate AC input signals of different frequencies; the terminal is used to record and display the space charge measurement results, AC voltage, AC response current, and to recover the space charge signal and calculate the dielectric parameter ε r '、ε r ", tanδ; the oscilloscope is used to display the measurement law of the space charge waveform; the voltage amplifier is used to amplify the AC input signals of different frequencies generated by the function generator into high-voltage AC signals of the same frequency; the nanosecond pulse source is used to generate ultrasonic signals reflecting the position of the space charge; the data acquisition card is used to measure the excitation voltage and response current of the frequency domain dielectric spectrum; the voltage divider is used to convert the AC high voltage into a low-voltage AC signal; the space charge measurement electrode housing is used to shield interference signals; the oil bath circulation device is used to control the temperature of the measurement electrode; the high-voltage electrode is used to apply the AC voltage and the pulse voltage to the sample at the same time; the semi-conductive layer is used to match the acoustic impedance of the sample; the sample is the material to be tested.

[0009] Optionally, the guard electrode is used to introduce the surface current to the ground potential; the current measuring electrode is used to measure the AC response current; the space charge measuring electrode is used to measure the space charge distribution; the piezoelectric film is used to convert the ultrasonic signal into an electrical signal; the signal amplifier amplifies the electrical signal generated by the piezoelectric film; the current detection unit converts the response current signal flowing through the sample into a voltage signal; during measurement, the capacitor size in the current detection unit is set, and the AC current is measured simultaneously under the pulse voltage required for space charge measurement, thereby realizing the joint synchronous measurement of space charge measurement and frequency domain dielectric spectrum under different frequency AC voltages.

[0010] Optionally, the measuring electrode adopts a four-electrode structure consisting of a high voltage electrode, a space charge measuring electrode, a current measuring electrode and a protective electrode.

[0011] In a second aspect, the present invention provides a method for joint synchronous measurement of space charge and high-voltage frequency domain dielectric spectrum, the method is implemented based on the joint synchronous measurement system of space charge and high-voltage frequency domain dielectric spectrum in the first aspect, and the method comprises:

[0012] Step 1: The voltage u of the high voltage arm H (t) and the current detection unit voltage uL (t) filter and calculate the voltage u(t) at both ends of the sample;

[0013] Step 2: Use Fast Fourier Transform (FFT) to obtain the sample voltage vector And the acquisition circuit voltage vector

[0014] Step 3: Combine the voltage vector of the acquisition circuit and the acquisition circuit impedance Z L Calculate the current vector And calculate the mode and initial phase of the sample impedance;

[0015] Step 4: Combine the size parameters to obtain the dielectric parameter ε r '、ε r ”、tanδ。

[0016] In the technical solution provided by the present invention, the system comprises a function generator, a terminal, an oscilloscope, a voltage amplifier, a nanosecond pulse source, a data acquisition card, a voltage divider, a space charge measurement electrode shell, an oil bath circulation device, a high voltage electrode, a semiconductive layer, a sample, a protective electrode, a current measurement electrode, a space charge measurement electrode, a piezoelectric film, a signal amplifier, and a current detection unit; the function generator and the terminal, the voltage amplifier are connected with the nanosecond pulse source; the terminal is also connected with the oscilloscope and the data acquisition card; the oscilloscope is also connected with the voltage divider and the signal amplifier; the oil bath circulation is arranged inside the space charge measurement electrode shell; the high voltage electrode, the semiconductive layer, and the sample are arranged at the bottom of the space charge measurement electrode shell in sequence; the protective electrode, the current measurement electrode, and the space charge measurement electrode are arranged in parallel at the bottom of the sample; the current detection unit is connected with the data acquisition card and the current measurement electrode, and the system solves the technical difficulties of the joint measurement of space charge and alternating current, avoids the current information loss and measurement interference caused by time-sharing measurement, ensures that the dielectric properties and space charge distribution of the insulating material can be accurately reflected under the high voltage electric field, thereby improving the application accuracy and reliability of the high voltage FDS technology in the insulation state assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of a joint synchronous measurement system provided by an embodiment of the present invention;

[0019] Figure 2A schematic diagram of the impedance variation law of a capacitor at different frequencies provided by an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a joint synchronous measurement method provided by an embodiment of the present invention.

[0021] Reference numerals:

[0022] 1-function generator, 2-terminal, 3-oscilloscope, 4-voltage amplifier, 5-nanosecond pulse source, 6-data acquisition card, 7-voltage divider, 8-space charge measurement electrode housing, 9-oil bath circulation device, 10-high voltage electrode, 11-semiconductive layer, 12-sample, 13-protective electrode, 14-current measurement electrode, 15-space charge measurement electrode, 16-piezoelectric film, 17-signal amplifier, 18-current detection unit. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be clear that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention are also intended to include plural forms, unless the context clearly indicates other meanings.

[0026] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0027] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0028] The insulation state of power equipment is crucial to the safe operation of the power system, and insulation state assessment has therefore become a key link in the operation and maintenance of power equipment. In recent years, frequency-domain dielectric spectroscopy (FDS) has become an important means of insulation state assessment because it can non-destructively obtain rich dielectric information of insulating materials, especially in the insulation detection of oil-immersed power equipment. FDS research mainly focuses on explaining the macroscopic dielectric response by analyzing the microscopic polarization and conductivity mechanism, so as to establish a model for evaluating the insulation state. However, conventional FDS measurements are usually performed at a lower voltage, and the dielectric properties under such measurement conditions cannot truly reflect the performance of the insulating material in the actual high-voltage operating environment. In addition, since the measured current is weak under low voltage conditions, it is easily affected by environmental noise and external interference, resulting in insufficient accuracy of the measurement results. Therefore, in recent years, the use of high-voltage FDS for insulation state assessment has gradually become a hot research direction, but this also brings new technical challenges.

[0029] Under high voltage environment, the accumulation of space charge inside the insulating material is prone to occur, which poses new challenges to the study of high voltage frequency domain dielectric response. The accumulation of space charge will not only change the electric field distribution inside the insulating material, but may also lead to the enhancement of the local electric field, thereby accelerating insulation aging and even causing serious problems such as partial discharge. Therefore, the traditional dielectric response model based on low voltage FDS is difficult to fully reflect the actual dielectric properties of insulating materials under high voltage conditions. Most of these models only consider the polarization and conductivity mechanisms, but ignore the influence of space charge effects, which greatly reduces their applicability under high voltage conditions, thereby limiting the application of high voltage FDS technology in insulation state assessment. In addition, under AC electric field, the accumulation and dissipation mechanism of space charge is more complicated than that of DC electric field. The accumulation of space charge under AC electric field will not only cause changes in the electric field distribution inside the material, but may also affect the measurement results of frequency domain dielectric spectrum to a certain extent. Since the dynamic change of space charge directly affects the current in the external circuit, the mechanism of space charge on dielectric response becomes more complex and changeable during the measurement of high voltage frequency domain dielectric spectrum.

[0030] Most of the current FDS studies measure space charge and dielectric spectra independently, lacking a means to measure both simultaneously. This leads to great difficulties in studying the microscopic mechanism of dielectric response of oil-paper insulation under high voltage conditions. Due to individual differences in samples and the dispersion of measurement results, this separate measurement method also makes it difficult to achieve effective comparative analysis between space charge and frequency domain dielectric spectra, which greatly limits the in-depth study of the dielectric response mechanism of oil-paper insulation under high electric fields. In addition, there is currently no method to directly obtain space charge distribution in high-voltage frequency domain dielectric spectrum measurements, which further increases the difficulty of research.

[0031] Therefore, developing a method that can synchronously measure space charge during high-voltage frequency-domain dielectric spectrum measurement will have important theoretical significance and practical application value for improving the accuracy of insulation status assessment and in-depth research on the microscopic mechanism of dielectric response of oil-paper insulation under high-voltage conditions. This technological breakthrough can not only provide a reliable foundation for the application of high-voltage FDS technology in insulation status assessment, but also promote the development of power equipment insulation monitoring technology towards higher accuracy and reliability.

[0032] Figure 1 A schematic diagram of a joint synchronous measurement system provided by an embodiment of the present invention, such as Figure 1 As shown, the system includes:

[0033] Function generator 1, terminal 2, oscilloscope 3, voltage amplifier 4, nanosecond pulse source 5, data acquisition card 6, voltage divider 7, space charge measurement electrode housing 8, oil bath circulation device 9, high voltage electrode 10, semi-conductive layer 11, sample 12, protection electrode 13, current measurement electrode 14, space charge measurement electrode 15, piezoelectric film 16, signal amplifier 17, current detection unit 18.

[0034] The function generator 1 and the terminal 2, the voltage amplifier 4 are connected to the nanosecond pulse source 5; the terminal 2 is also connected to the oscilloscope 3 and the data acquisition card 6; the oscilloscope 3 is also connected to the voltage divider 7 and the signal amplifier 17; the oil bath circulation device 9 is arranged inside the space charge measurement electrode shell 8; the high voltage electrode 10, the semi-conductive layer 11, and the sample 12 are arranged in sequence at the bottom of the space charge measurement electrode shell 8; the protective electrode 13, the current measurement electrode 14, and the space charge measurement electrode 15 are arranged in parallel at the bottom of the sample 12; the current detection unit 18 is connected to the data acquisition card 6 and the current measurement electrode 14.

[0035] In the embodiment of the present invention, the function generator 1 is used to generate AC input signals of different frequencies; the terminal 2 is used to record and display the space charge measurement results, AC voltage, AC response current, and to recover the space charge signal and calculate the dielectric parameter ε. r '、ε r", tanδ; oscilloscope 3 is used to display the measurement law of space charge waveform; voltage amplifier 4 is used to amplify the AC input signals of different frequencies generated by function generator 1 into high-voltage AC signals of the same frequency; nanosecond pulse source 5 is used to generate ultrasonic signals reflecting the position of space charge; data acquisition card 6 is used to measure the excitation voltage and response current of frequency domain dielectric spectrum; voltage divider 7 is used to convert AC high voltage into low-voltage AC signal; space charge measurement electrode housing 8 is used to shield interference signals; oil bath circulation device 9 is used to control the temperature of measurement electrode; high-voltage electrode 10 is used to apply AC voltage and pulse voltage to sample 12 at the same time; semi-conductive layer 11 is used to match the acoustic impedance of sample 12; sample 12 is the material to be tested.

[0036] In the embodiment of the present invention, the protective electrode 13 is used to introduce the surface current to the ground potential; the current measuring electrode 14 is an electrode for measuring the AC response current; the space charge measuring electrode 15 is an electrode for measuring the space charge distribution; the piezoelectric film 16 is used to convert the ultrasonic signal into an electrical signal; the signal amplifier 17 amplifies the electrical signal generated by the piezoelectric film 16; the current detection unit 18 converts the response current signal flowing through the sample 12 into a voltage signal; during measurement, by setting the capacitance size in the current detection unit 18, the AC current is measured simultaneously under the pulse voltage required for the space charge measurement, thereby realizing the joint synchronous measurement of the space charge measurement and the frequency domain dielectric spectrum under different frequency AC voltages.

[0037] In the embodiment of the present invention, the measuring electrode adopts a four-electrode structure consisting of a high voltage electrode 10 , a space charge measuring electrode 15 , a current measuring electrode 14 , and a protection electrode 13 .

[0038] In an embodiment of the present invention, a four-electrode structure is used to prevent the current generated by the piezoelectric film in the acoustic-to-electric conversion from affecting the AC current measurement, thereby realizing independent measurement of space charge and AC current. When designing the electrodes, making the two electrodes with the same area can achieve the same current flowing through the two electrodes, which is convenient for data correlation analysis.

[0039] The present invention intends to adopt a resistor-capacitor parallel circuit, connecting a coupling capacitor much larger than the sample capacitance in parallel with the sampling resistor, and utilizing its high-frequency low impedance-low-frequency high impedance characteristics. Figure 2As shown, the capacitance impedance decreases inversely with the increase of frequency. In the study of AC current signal measurement, the traditional method usually relies on direct measurement, but this method may cause potential damage to the measuring instrument when facing high-frequency pulse current. Therefore, in order to improve the accuracy and safety of measurement, the present invention proposes an improved measurement method based on a resistor-capacitor parallel circuit. The core principle of this method is to utilize the frequency-dependent characteristics of the resistor-capacitor parallel circuit, that is, the coupling capacitor exhibits different impedance characteristics at different frequencies. Under high-frequency conditions, the coupling capacitor exhibits low impedance, which can effectively reduce the pulse voltage formed by the pulse current passing through it, thereby reducing the impact and damage of these pulse voltages on subsequent measurement circuits and instruments. This characteristic enables the measuring instrument to work normally without being damaged even in the presence of large pulse currents at high frequencies. On the other hand, at AC frequencies, the resistor-capacitor parallel circuit exhibits the characteristics of low impedance at high frequencies and high impedance at low frequencies. The high impedance characteristics at low frequencies make the overall impedance of the circuit close to the resistance value of the sampling resistor, which means that when measuring AC signals, no additional switch switching is required to directly complete the measurement. This feature significantly simplifies the measurement process, improves measurement efficiency, and reduces potential errors in the measurement process. In addition, in the actual measurement process, the magnitude of the AC current gradually decreases as the frequency decreases. This relationship between frequency and current amplitude requires that the resistance of the sampling resistor be adjusted accordingly according to the change in the measurement frequency. When the frequency is low, the current decreases, and the resistance of the sampling resistor needs to be increased to maintain sufficient measurement signal strength. This adaptive adjustment capability is an important advantage of the present invention when measuring AC currents of different frequencies.

[0040] In order to solve the influence of the impedance of the RC circuit itself on the phase and amplitude of the collected AC signal, the present invention intends to obtain an impedance database of different collection circuits (RC circuits) at different frequencies through an impedance analyzer.

[0041] Figure 3 A schematic diagram of a joint synchronous measurement method provided by an embodiment of the present invention is shown in FIG. Figure 3 As shown, the method is implemented based on a joint synchronous measurement system of space charge and high-voltage frequency domain dielectric spectrum, and the method includes:

[0042] Step 1: The voltage u of the high voltage arm H (t) and the current detection unit voltage u L (t) filter and calculate the voltage u(t) at both ends of the sample;

[0043] Step 2: Use Fast Fourier Transform (FFT) to obtain the sample voltage vector And the acquisition circuit voltage vector

[0044] Step 3: Combine the voltage vector of the acquisition circuit and the acquisition circuit impedance Z L Calculate the current vector And calculate the mode and initial phase of the sample impedance;

[0045] Step 4: Combine the size parameters to obtain the dielectric parameter ε r '、ε r ”、tanδ。

[0046] The present invention breaks through the bottleneck that the space charge and frequency domain dielectric spectrum cannot be measured synchronously in the prior art, and realizes the simultaneous measurement of space charge and AC current under nanosecond pulse high voltage conditions. This innovation avoids the information loss and measurement interference caused by traditional time-sharing measurement, ensures the synchronization and consistency of dielectric properties and space charge distribution under high voltage electric field, and makes the measurement results more accurate and reliable. The RC parallel circuit measurement method introduced by the present invention effectively reduces the impact of high-frequency pulse current on the measurement circuit by utilizing the frequency-dependent characteristics of the RC circuit, and avoids the damage of high-frequency pulse voltage to the measuring instrument in the traditional method. In addition, the method simplifies the measurement process, reduces frequent switching operations, improves measurement efficiency and accuracy, and is an important improvement on the prior art. The present invention realizes the accurate recovery of real current signals at different frequencies and the accurate calculation of dielectric parameters by establishing an impedance database and combining FFT technology. Compared with the prior art, the method of the present invention effectively solves the influence of the impedance of the RC circuit itself on the measurement results, and significantly improves the measurement accuracy of the high-voltage frequency domain dielectric spectrum. The prior art often faces safety issues of measuring instruments under high voltage conditions, while the present invention effectively protects the measuring instruments through innovative measurement methods and circuit designs, enhances the reliability and safety of the measurement process, and makes the measurement under high voltage conditions more controllable and safe.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. The core innovation of the present invention is to propose a method that can realize the synchronous measurement of space charge and high-voltage frequency domain dielectric spectrum under nanosecond pulse high voltage conditions. By rationally setting the capacitor in the current detection unit, the AC current can be accurately measured while the space charge is measured, thereby ensuring the synchronization of space charge and frequency domain dielectric spectrum and the consistency of data during the measurement process. This technological breakthrough overcomes the information loss and measurement interference problems caused by time-sharing measurement in traditional methods, and is the key protection point of the present invention.

[0049] 2. The present invention proposes an improved measurement method based on a resistor-capacitor parallel circuit, which utilizes the frequency-dependent characteristics of the resistor-capacitor parallel circuit to achieve high-frequency current suppression under nanosecond pulse high-voltage conditions. This method can effectively reduce the impact of pulse current on the measurement circuit and protect the measuring instrument. At the same time, it simplifies the measurement process of AC current and avoids frequent switching operations in traditional methods, thereby improving measurement efficiency and accuracy. This measurement method is an important innovation of the present invention in measurement technology and is a technical solution that needs to be protected.

[0050] 3. The present invention proposes a method for establishing an impedance database at different frequencies through an impedance analyzer, and combines FFT technology to restore the real current frequency domain signal, thereby accurately calculating the dielectric parameters of the sample. This method ensures the measurement accuracy of the high-voltage frequency domain dielectric spectrum, which is an important innovation and protection content of the present invention in data processing and analysis.

[0051] In the technical solution provided by the present invention, the system comprises a function generator, a terminal, an oscilloscope, a voltage amplifier, a nanosecond pulse source, a data acquisition card, a voltage divider, a space charge measurement electrode housing, an oil bath circulation device, a high voltage electrode, a semi-conductive layer, a sample, a protective electrode, a current measurement electrode, a space charge measurement electrode, a piezoelectric film, a signal amplifier, and a current detection unit; the function generator and the terminal, the voltage amplifier are connected to the nanosecond pulse source; the terminal is also connected to the oscilloscope and the data acquisition card; the oscilloscope is also connected to the voltage divider and the signal amplifier; the oil bath circulation is arranged inside the space charge measurement electrode housing; the high voltage electrode, the semi-conductive layer, the sample, the protective electrode, the current measurement electrode, the space charge measurement electrode, the piezoelectric film, the signal amplifier, and the current detection unit; the function generator and the terminal, the voltage amplifier are connected to the nanosecond pulse source; the terminal is also connected to the oscilloscope and the data acquisition card; the oscilloscope is also connected to the voltage divider and the signal amplifier; the oil bath circulation is arranged inside the space charge measurement electrode housing; the high voltage electrode, the semi-conductive layer, the protective electrode, the current measurement electrode, the space charge measurement electrode, the piezoelectric film, the signal amplifier, and the current detection unit; the The layer and the sample are arranged in sequence at the bottom of the space charge measurement electrode shell; the protection electrode, the current measuring electrode and the space charge measuring electrode are arranged in parallel at the bottom of the sample; the current detection unit is connected with the data acquisition card and the current measuring electrode. The system solves the technical problem of joint measurement of space charge and AC current, and directly measures the AC current under nanosecond pulse high voltage conditions, thereby avoiding the current information loss and measurement interference caused by time-sharing measurement, ensuring that the dielectric properties and space charge distribution of the insulating material can be accurately reflected under the high voltage electric field, thereby improving the application accuracy and reliability of high-voltage FDS technology in insulation status assessment.

[0052] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A joint synchronous measurement system for space charge and high voltage frequency domain dielectric spectrum, characterized in that: The system comprises: Function generator (1), terminal (2), oscilloscope (3), voltage amplifier (4), nanosecond pulse source (5), data acquisition card (6), voltage divider (7), space charge measurement electrode housing (8), oil bath circulation device (9), high voltage electrode (10), semiconductive layer (11), sample (12), protection electrode (13), current measurement electrode (14), space charge measurement electrode (15), piezoelectric film (16), signal amplifier (17), current detection unit (18); The function generator (1) and the terminal (2) and the voltage amplifier (4) are connected to the nanosecond pulse source (5); the terminal (2) is also connected to the oscilloscope (3) and the data acquisition card (6); the oscilloscope (3) is also connected to the voltage divider (7) and the signal amplifier (17); the oil bath circulation device (9) is arranged inside the space charge measurement electrode shell (8); the high voltage electrode (10), the semiconductive layer (11), and the sample (12) are arranged in sequence at the bottom of the space charge measurement electrode shell (8); the protection electrode (13), the current measurement electrode (14), and the space charge measurement electrode (15) are arranged in parallel at the bottom of the sample (12); the current detection unit (18) is connected to the data acquisition card (6) and the current measurement electrode (14); The current detection unit (18) adopts a resistor-capacitor parallel circuit. By utilizing the frequency-dependent characteristics of the resistor-capacitor parallel circuit, under high-frequency conditions, the coupling capacitor exhibits low impedance, which can reduce the pulse voltage formed by the pulse current passing through it; the high impedance characteristics under low frequency make the overall impedance of the circuit close to the resistance value of the sampling resistor, and when measuring AC signals, no additional switch switching is required, and the measurement can be completed directly; during measurement, by setting the capacitor size in the current detection unit (18), the AC current is measured simultaneously under the pulse voltage required for space charge measurement, thereby realizing the joint synchronous measurement of space charge and frequency domain dielectric spectrum under different frequency AC voltages.

2. The combined synchronous measurement system of space charge and high voltage frequency domain dielectric spectrum according to claim 1 is characterized in that: The function generator (1) is used to generate AC input signals of different frequencies; the terminal (2) is used to record and display the space charge measurement results, AC voltage, AC response current, and to recover the space charge signal and calculate the dielectric parameters. ε r '、 ε r ''、tanδ ; The oscilloscope (3) is used to display the measurement law of the space charge waveform; the voltage amplifier (4) is used to amplify the AC input signals of different frequencies generated by the function generator (1) into high-voltage AC signals of the same frequency; the nanosecond pulse source (5) is used to generate an ultrasonic signal reflecting the position of the space charge; the data acquisition card (6) is used to measure the excitation voltage and response current of the frequency domain dielectric spectrum; the voltage divider (7) is used to convert the AC high voltage into a low-voltage AC signal; the space charge measurement electrode housing (8) is used to shield interference signals; the oil bath circulation device (9) is used to control the temperature of the measurement electrode; the high-voltage electrode (10) is used to apply the AC voltage and the pulse voltage to the sample (12) at the same time; the semi-conductive layer (11) is used to match the acoustic impedance of the sample (12); the sample (12) is the material to be measured.

3. The combined synchronous measurement system of space charge and high voltage frequency domain dielectric spectrum according to claim 1 is characterized in that: The protection electrode (13) is used to introduce the surface current to the ground potential; the current measuring electrode (14) is an electrode for measuring the AC response current; the space charge measuring electrode (15) is an electrode for measuring the space charge distribution; the piezoelectric film (16) is used to convert the ultrasonic signal into an electrical signal; the signal amplifier (17) amplifies the electrical signal generated by the piezoelectric film (16); and the current detection unit (18) converts the response current signal flowing through the sample (12) into a voltage signal.

4. The combined synchronous measurement system of space charge and high voltage frequency domain dielectric spectrum according to claim 1 is characterized in that: The measuring electrode adopts a four-electrode structure consisting of a high voltage electrode (10) - a space charge measuring electrode (15) - a current measuring electrode (14) - a protective electrode (13).

5. A method for the joint synchronous measurement of space charge and high voltage frequency domain dielectric spectrum, characterized in that: The method is implemented based on the joint synchronous measurement system of space charge and high-voltage frequency-domain dielectric spectrum according to claim 1, and the method comprises: Step 1: High voltage arm voltage and the current sensing unit voltage Perform filtering and calculate the voltage across the sample ; Step 2: Use Fast Fourier Transform (FFT) to obtain the sample voltage vector And the acquisition circuit voltage vector ; Step 3: Combine the voltage vector of the acquisition circuit and acquisition circuit impedance Z L Calculate the current vector , and calculate the mode and initial phase of the sample impedance; Step 4: Combine the size parameters to obtain the dielectric parameters ε r '、ε r ''、tanδ .

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