Integrated high-voltage insulation resistance test and dielectric response test integrated method

Abstract

The invention relates to an integrated high-voltage insulation resistance test and dielectric response test integrated method, and belongs to the field of electrical engineering. According to the invention, the sampling resistors are connected in series, the measurement of a micro current signal is converted into the measurement of sampling impedance voltage, and the anti-interference capability and the measurement precision are effectively improved. Insulation resistance is measured through the high-voltage direct-current power supply, the frequency range of frequency domain dielectric spectrum testing is expanded to direct current, dielectric response testing is carried out through the high-voltage alternating-current power supply, and the dielectric state of a medium under the actual operation working condition is reflected more accurately. The method has the advantages of being easy and convenient to operate, high in anti-interference capacity, high in measurement precision, wide in frequency range and the like, and can be widely applied to insulation state evaluation and fault diagnosis of high-voltage electrical equipment.

Description

Technical Field

[0001] The invention belongs to the field of electrical engineering and relates to an integrated method for high-voltage insulation resistance testing and dielectric response testing. Background Art

[0002] With the development of dielectric response technology, frequency domain dielectric spectroscopy has gradually been studied in depth by domestic and foreign scholars and has achieved certain results due to its unique advantages, such as carrying rich insulation information and the possibility of online monitoring. There are two main types of existing frequency domain dielectric spectroscopy measurement equipment. One can achieve high-precision measurement of dielectric spectra in an extremely wide frequency range. The representative instrument is the Novocontrol concept 40 broadband dielectric impedance spectrometer, but it is large in size and limited to laboratory testing and cannot be used on site. The other is suitable for field testing of dielectric response, and the main devices used are DIRANA equipment and IDAX300 equipment.

[0003] However, for the existing frequency domain dielectric spectrum technology, the lowest frequency point of the test is 0.1mHz, and the frequency range is not extended to DC; and the existing test voltage is low, and most of the voltage used is 200V, which belongs to low-voltage measurement. There are two problems in the application of low-voltage dielectric response testing to actual high-voltage equipment: (1) The low-voltage test response current is small, the signal-to-noise ratio is low, and the test error is large due to the interference of the on-site electromagnetic environment; (2) The test voltage is much smaller than the operating voltage, and the voltage correlation of the dielectric response microscopic process will cause the measurement results to fail to reflect the dielectric state under operating conditions. Summary of the invention

[0004] In view of this, the object of the present invention is to provide an integrated method for high-voltage insulation resistance testing and dielectric response testing. In view of the frequency range limitations of the broadband dielectric spectrometer, the insulation resistance measurement is realized, and the lowest frequency point of the existing frequency domain dielectric spectrum test, 0.1mHz, is extended to direct current, that is, the frequency of 0 is also considered to be part of the dielectric spectrum. At the same time, in view of the shortcomings of the existing dielectric response test, such as small response current, weak anti-interference ability, and inability to achieve accurate measurement, the method of series sampling resistance is used for voltage division, and the current measured at the nA level is converted into the voltage measured at the V level, thereby improving the anti-interference ability and achieving accurate measurement of the dielectric spectrum.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The integrated method of high voltage insulation resistance test and dielectric response test includes the following steps:

[0007] A test platform is provided, which includes a signal generator, a high voltage amplifier, an adjustable sampling impedance, a signal acquisition module and a computer;

[0008] Connect the product to be tested to the test platform;

[0009] When a high-voltage DC power supply is used, a DC voltage is output to the test object through a signal generator, and the voltage across the sampling impedance is measured through an adjustable sampling impedance, and the insulation resistance of the test object is calculated based on the measured value;

[0010] When a high-voltage AC power supply is used, an AC voltage is output to the test piece through a signal generator, and the voltage across the sampling impedance is measured through an adjustable sampling impedance, and the voltage of the voltage divider is measured through a voltage divider. The collected voltage signal is input into a signal acquisition module, and the signal acquisition module synchronously collects the voltage signal of the voltage divider and the voltage signal of the sampling impedance, and the collected voltage signal is input into a computer. The computer performs Fourier transform on the collected voltage signal, extracts the amplitude and phase of the fundamental frequency component, and calculates the dielectric parameters of the test piece based on this.

[0011] Furthermore, the adjustable sampling impedance is a resistor with an adjustable resistance value.

[0012] Furthermore, the signal acquisition module includes a high-voltage probe, a voltage divider and two voltage signal channels.

[0013] Furthermore, the computer calculates the dielectric parameters of the test sample according to the collected voltage signal, including the complex capacitance constant and the dielectric loss tangent.

[0014] Furthermore, the signal generator is an AC signal generator, and the high-voltage amplifier is a high-voltage AC amplifier.

[0015] Furthermore, the signal generator is a DC signal generator, and the high-voltage amplifier is a high-voltage DC amplifier.

[0016] The beneficial effect of the present invention is that it can realize the integrated measurement of high-voltage dielectric spectrum and insulation resistance by only using different input signal types and combining sampling impedance on the same platform. The measured tiny current signal is converted into the measured sampling impedance voltage, which has high anti-interference ability and improves the accuracy of high-voltage frequency domain dielectric spectrum; and when a high-voltage DC power supply is used, the insulation resistance can be obtained by combining with variable sampling impedance, so as to expand the frequency range to DC.

[0017] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 This is the equivalent circuit diagram of the high voltage frequency domain dielectric response test;

[0020] Figure 2 Extend the Debye model for insulating media;

[0021] Figure 3 It is a high voltage AC power source;

[0022] Figure 4 It is the vector diagram of high voltage frequency domain dielectric response test. DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and the features in the embodiments can be combined with each other without conflict.

[0024] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0025] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0026] The present invention proposes an integrated method for high-voltage insulation resistance testing and high-voltage dielectric response testing, which can realize the measurement of dielectric spectrum and insulation resistance on the same platform. The measured tiny response current is converted into the measured voltage by using a series sampling resistor, which improves the anti-interference ability and reduces the error. While measuring the insulation resistance of the test sample, the frequency range of the wide-band dielectric spectrometer is expanded to DC.

[0027] The equivalent circuit of the integrated high voltage insulation resistance test and high voltage dielectric response test is as follows: Figure 1 When an AC power supply is used, a high voltage dielectric response test can be performed, and when a high voltage DC power supply is used, the insulation resistance value of the test piece can be obtained.

[0028] (1) Insulation resistance measurement

[0029] The sample Z1 has dielectric relaxation phenomenon, which can be equivalent to polarization processes with different response time constants. Therefore, multiple RC branches are connected in parallel to represent multiple polarization processes, that is, the Z1 equivalent model is the dielectric extended Debye model, such as Figure 2 In the model, C0 is called the geometric capacitance branch, R0 is called the insulation resistance branch, and multiple RC branches in parallel are called polarization branches.

[0030] exist Figure 1 The platform shown can measure the insulation resistance of the test sample when a high-voltage DC power supply is used. However, the insulation resistance is very large, resulting in a small response current, which is as small as pA or nA. The general current field measurement is easily interfered. The present invention adopts a series variable sampling impedance method, and uses the sampling impedance to access a larger resistance value to play a voltage dividing role. After 60 seconds of pressure application, Figure 2 The capacitor branch C0, polarization branch R1 C1, R2 C2, ...R n C n Attenuates to zero, at this time measure the voltage across the sampling impedance to obtain the value of the insulation resistance R0. The calculation of the insulation resistance of the test piece is as follows:

[0031]

[0032] Where R′=R M / / R / / R P , R M is a large resistor (for protection, to prevent floating); R is a resistor with adjustable resistance value; R P is the input resistance of the sampling probe (considered as a constant). Different from the previous high-voltage frequency domain dielectric response test method, the lowest frequency point of the existing frequency domain dielectric spectrum test is 0.1mHz. This patent expands the frequency range of the broadband dielectric spectrometer to DC while measuring the insulation resistance of the test product, that is, the DC characteristic, that is, the frequency of 0 is also considered to be part of the dielectric spectrum, realizing the expansion of the dielectric spectrum frequency characteristic test.

[0033] (2) High voltage AC dielectric response test

[0034] The high voltage dielectric response test uses an AC signal generator to output AC voltage to the test product through a high voltage amplifier, such as Figure 3As shown. After the adjustable sampling impedance is grounded to form a loop, the signal acquisition module synchronously collects the voltage signal of the voltage divider through two voltage information channels. The voltage signal of the sampling impedance The computer simultaneously performs Fourier transform on the collected voltage signal to extract the amplitude and phase of the fundamental frequency component, and calculates the dielectric parameters of the test piece based on this.

[0035] On the one hand, the traditional dielectric response test voltage is mostly 200V low-voltage measurement, the response current is small, and the measurement is easily interfered. This patent uses an AC signal generator to output AC voltage to the test product through a high-voltage amplifier to increase the response current and reduce the error. On the other hand, the dielectric response microscopic process has voltage correlation, and choosing high-voltage measurement can better reflect the dielectric state of the medium under actual operating conditions.

[0036] The nA level current signal is converted into a voltage signal on the sampling resistor by using a series sampling resistor, which increases the magnitude of the measurement signal, improves the anti-interference ability, and reduces the error. The specific measurement process is as follows:

[0037] The signal is measured by the high voltage probe of the signal acquisition module through a voltage divider. The oscilloscope uses two voltage signal channels to measure synchronously. and Phase and amplitude information, can be Figure 4 The vector relationship is calculated as:

[0038]

[0039] Dielectric response current The voltage of the sampling resistor can be collected The adjustable sampling impedance is calculated and the adjustable resistance is adjusted with the frequency, which can always make The amplitude is maintained near a certain set value, which greatly improves the measurement accuracy:

[0040]

[0041] According to the dielectric voltage and the response current The complex capacitance constant C* and dielectric loss tangent tanδ can be obtained:

[0042]

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. An integrated method for high voltage insulation resistance test and dielectric response test, characterized in that: The following steps are involved: A test platform is provided, which includes a signal generator, a high voltage amplifier, an adjustable sampling impedance, a signal acquisition module and a computer; Connect the product to be tested to the test platform; When a high-voltage DC power supply is used, a DC voltage is output to the test object through a signal generator, and the voltage across the sampling impedance is measured through an adjustable sampling impedance, and the insulation resistance of the test object is calculated based on the measured value; When a high-voltage AC power supply is used, an AC voltage is output to the test piece through a signal generator, and the voltage across the sampling impedance is measured through an adjustable sampling impedance, and the voltage of the voltage divider is measured through a voltage divider. The collected voltage signal is input into a signal acquisition module, and the signal acquisition module synchronously collects the voltage signal of the voltage divider and the voltage signal of the sampling impedance, and the collected voltage signal is input into a computer. The computer performs Fourier transform on the collected voltage signal, extracts the amplitude and phase of the fundamental frequency component, and calculates the dielectric parameters of the test piece based on this.

2. The integrated high voltage insulation resistance test and dielectric response test method according to claim 1 is characterized in that: The adjustable sampling impedance is a resistor with an adjustable resistance value.

3. The integrated high voltage insulation resistance test and dielectric response test method according to claim 1 is characterized in that: The signal acquisition module includes a high-voltage probe, a voltage divider and two voltage signal channels.

4. The integrated high voltage insulation resistance test and dielectric response test method according to claim 1 is characterized in that: The computer calculates the dielectric parameters of the test sample according to the collected voltage signal, including the complex capacitance constant and the dielectric loss tangent.

5. The integrated high voltage insulation resistance test and dielectric response test method according to claim 1 is characterized in that: The signal generator is an AC signal generator, and the high-voltage amplifier is a high-voltage AC amplifier.

6. The integrated high voltage insulation resistance test and dielectric response test method according to claim 1, characterized in that: The signal generator is a DC signal generator, and the high-voltage amplifier is a high-voltage DC amplifier.

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