Transformer substation transient electric field sensor calibration method and system

Abstract

The invention discloses a transformer substation transient electric field sensor calibration method and system, and relates to the technical field of transformer substations, and the method comprises the steps: placing an electric field sensor in a transverse electromagnetic wave cell, and placing a field intensity probe at the upper half part of the cell to measure the electric field intensity. The first feed-in power is recorded by changing the excitation source injection cell. Then, the field intensity probe is taken out, and the electric field sensor is put back to the original position for steady-state calibration. Constructing a transient calibration test loop, generating a high-voltage pulse signal, thereby generating a transient electric field environment, and carrying out transient calibration on the electric field sensor; according to the invention, high-precision steady-state and transient-state calibration of the sensor is realized, and the measurement accuracy and reliability are obviously improved; the calibration process is simplified, the operation convenience is improved, and the compatibility of the sensor in a complex electromagnetic environment is enhanced; accurate calibration is beneficial for finding potential problems, prolonging the service life of the sensor and reducing the maintenance cost, so that the safety and the stability of a power system are integrally improved.

Description

Technical Field

[0001] The present invention relates to the technical field of substations, and in particular to a method and system for calibrating a transient electric field sensor of a substation. Background Art

[0002] The very fast transient phenomena generated during the GIS switch operation process include the following three points: the transient overvoltage inside the GIS is generally called VFTO, which mainly affects the insulation of the internal primary equipment, causing insulation coordination failure, insulation equipment damage and other hazards; the external transient overvoltage coupled between the GIS shell and the earth is called TEV, which mainly threatens the external secondary equipment and personal safety; in addition, there are transient electromagnetic fields radiated into the station space, which will also affect the secondary equipment; the above three parts constitute the very fast transient process of GIS switch operation. Therefore, the measuring sensors placed at the end of the electronic transformer are voltage sensors and electric field sensors, and in-depth research is needed on voltage sensors and electric field sensors; many smart substations at home and abroad have applied electronic transformers, but electronic transformers have added digital acquisition circuits and communication network systems. While having many technical advantages, the close installation with primary equipment will also cause new problems for traditional transformers. GIS interrupters, disconnectors, grounding switches, and single-phase grounding short circuit faults will all generate very fast transient overvoltages (VFTO), among which the disconnector is the main cause. During the normal switching operation of the substation, a transient ground potential rise of several kV and a transient electric field of several kV / m are generated. The transformer acquisition card is arranged near the primary side and is subject to an extremely harsh electromagnetic environment. When the electronic transformer is put into use, it needs to be tested in a simulated electromagnetic environment to see if it can withstand the harsh electromagnetic environment.

[0003] Pulse electric field testing in a complex electromagnetic environment places high demands on the electromagnetic compatibility of electronic equipment. In electric field testing, the power supply problem of the test device has always been one of the hot topics of concern to scholars. The power supply part generally uses batteries. Traditional batteries generally have insufficient endurance. In order to meet the test requirements, batteries need to be replaced frequently; because the battery size and capacity cannot be taken into account, the sensor cannot make a breakthrough in miniaturization design. Frequent entry of personnel into the measurement site increases the danger. The test equipment is required to have an extremely wide test bandwidth and a large linear dynamic range. The test often occurs in the near field area, so the test equipment is required to be as small as possible. In the existing technology, laser batteries are used to power the equipment, which has the problems of short power supply time, frequent battery replacement, and interference signals to surrounding electronic equipment; the electric field sensor also needs to be calibrated before it can be used normally. The calibration of the system is divided into transient calibration and steady-state calibration. Transient calibration requires calibrating the rise time in the time domain, which needs to meet the requirements of the nanosecond rising edge, and steady-state calibration is to achieve -3dB bandwidth calibration. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to provide an electric field sensor power supply method for use in harsh environments and a sensor calibration method used in conjunction therewith.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a method for calibrating a transient electric field sensor in a substation, comprising:

[0008] The electric field sensor is placed in the transverse electromagnetic wave chamber, and the field strength probe is placed in the upper part of the transverse electromagnetic wave chamber to measure the electric field strength;

[0009] Change the excitation source injected into the beginning of the transverse electromagnetic wave chamber and record the first feeding power;

[0010] Take out the field strength probe, put the electric field sensor into the position where the field strength probe was originally placed, and perform steady-state calibration;

[0011] Construct a transient calibration test loop to generate a high-voltage pulse signal, and further generate a transient calibration test electric field environment;

[0012] Install the electric field sensor in the transient calibration test electric field environment to perform transient calibration.

[0013] As a preferred solution for the calibration method of the transient electric field sensor of the substation, wherein:

[0014] The measuring electric field strength comprises:

[0015] The electric field strength measured by the field strength probe is used as the field strength of the transverse electromagnetic wave chamber, and a coaxial load is used at the end of the transverse electromagnetic wave chamber to achieve impedance matching.

[0016] As a preferred solution for the calibration method of the transient electric field sensor of the substation, wherein:

[0017] The first feed-in power includes the electric field strength measured by the field strength probe at different frequencies and the feed-in power of the transverse electromagnetic wave chamber.

[0018] As a preferred solution for the calibration method of the transient electric field sensor of the substation, wherein:

[0019] The steady-state calibration comprises:

[0020] The first feed power is fed into the transverse electromagnetic wave chamber, the output voltage of the electric field sensor is measured, the antenna coefficient is calculated, the radiation immunity of the substation transient electric field sensor is evaluated, and the steady-state calibration is completed.

[0021] As a preferred solution for the calibration method of the transient electric field sensor of the substation, wherein:

[0022] The generating of the high voltage pulse signal and further generating the transient calibration test electric field environment comprises:

[0023] The working data of the high-voltage DC power supply is adjusted through the first control circuit, and a trigger signal is generated to control the sharpening circuit to generate a high-voltage pulse signal; the output high-voltage pulse signal is transmitted to the test transmission line to generate an electric field that meets the test requirements; the pulse is absorbed by the distributed terminal matching load resistor to avoid reflection.

[0024] As a preferred solution for the calibration method of the transient electric field sensor of the substation, wherein:

[0025] The electric field sensor is installed in a transient calibration test electric field environment, and the transient calibration is performed including:

[0026] The electric field sensor is installed in the anechoic chamber to measure the electric field generated in the anechoic chamber and the electric field data and waveform inside the test body, and the measured data is transmitted outside the anechoic chamber to display, read and store the data;

[0027] The electric field sensor comprises a detector and a receiver, wherein the detector comprises a photocell, a power supply voltage stabilization module, an electric-to-optical circuit and an electric field sensing unit, and the receiver comprises a power supply module, a semiconductor laser, an optical-to-electrical circuit and an electric field detection unit;

[0028] The power module, laser, power supply optical fiber, and photocell are connected in sequence; the power module supplies power to the light-to-electricity circuit; the photocell supplies power to the electric-to-light circuit through the power supply voltage stabilizing module; the light-to-electricity circuit and the electric-to-light circuit are connected through the signal optical fiber, the electric field sensing unit is connected to the input end of the electric-to-light circuit, and the electric field detection unit is connected to the output end of the light-to-electricity circuit.

[0029] As a preferred solution for the calibration method of the transient electric field sensor of the substation, wherein:

[0030] The electric field sensing unit includes a monopole antenna, a voltage-dividing capacitor, an impedance conversion circuit, an amplifying circuit, a light transmitting circuit, a light receiving circuit and a receiving device;

[0031] The monopole antenna, the impedance conversion circuit, and the amplifier circuit are connected in sequence; one end of the voltage-dividing capacitor is connected between the monopole antenna and the impedance conversion circuit, and the other end is grounded; the output end of the amplifier circuit is converted into an optical signal by the optical transmitting circuit, and then transmitted to the optical receiving circuit via the optical fiber, and then converted into an electrical signal again for transmission to the receiving device; the voltage received by the monopole antenna is divided by the voltage-dividing capacitor, input into the transmitting circuit, transmitted to the receiving circuit by the optical fiber, and received and displayed by the oscilloscope;

[0032] When the monopole antenna is an electrically small antenna, the effective length is equal to half the physical length of the rod antenna; the calculation formula for the effective length of the rod antenna is as follows:

[0033]

[0034] Wherein, h represents the length of the antenna element; λ represents the wavelength corresponding to the operating frequency of the antenna element.

[0035] In a second aspect, an embodiment of the present invention provides a substation transient electric field sensor calibration system, comprising:

[0036] A field strength measurement module is used to place an electric field sensor in the transverse electromagnetic wave chamber, and place a field strength probe in the upper part of the transverse electromagnetic wave chamber to measure the electric field strength;

[0037] A feeding power recording module is used to change the excitation source injected into the beginning of the transverse electromagnetic wave chamber and record the first feeding power;

[0038] The steady-state calibration module is used to take out the field strength probe, put the electric field sensor into the position where the field strength probe was originally placed, and perform steady-state calibration;

[0039] A transient calibration environment generation module is used to construct a transient calibration test loop, generate a high-voltage pulse signal, and further generate a transient calibration test electric field environment;

[0040] The transient calibration module is used to install the electric field sensor in a transient calibration test electric field environment to perform transient calibration.

[0041] In a third aspect, an embodiment of the present invention provides a computing device, including:

[0042] Memory and processor;

[0043] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the one or more programs are executed by the one or more processors, the one or more processors implement the substation transient electric field sensor calibration method as described in any embodiment of the present invention.

[0044] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the substation transient electric field sensor calibration method.

[0045] Beneficial effects of the present invention: By constructing a transverse electromagnetic wave chamber (TEM chamber) and a transient calibration test circuit, the present invention can perform steady-state and transient calibration on the sensor with high precision, thereby calibrating the transient electric field sensor of the substation and improving its measurement accuracy and reliability. The present invention simplifies the calibration process, making the operation more convenient, and improves the compatibility of the sensor in a complex electromagnetic environment, ensuring its stable operation. In addition, accurate calibration helps to discover potential problems, extend the service life of the sensor, reduce maintenance costs, and improve the safety and stability of the power system as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0047] Figure 1 is an overall flow chart of the substation transient electric field sensor calibration method according to the first embodiment of the present invention;

[0048] Figure 2 It is a structural diagram of an electric field sensor framework of a method for calibrating a transient electric field sensor in a substation according to a first embodiment of the present invention;

[0049] Figure 3 It is a structural block diagram of an antenna system of a method for calibrating a transient electric field sensor in a substation according to a first embodiment of the present invention;

[0050] Figure 4It is a schematic diagram of a transient electric field sensor calibration test in a simulation example of a substation transient electric field sensor calibration method according to a second embodiment of the present invention;

[0051] Figure 5 It is a circuit diagram of a transient calibration test loop in a simulation example of a method for calibrating a transient electric field sensor in a substation according to a second embodiment of the present invention;

[0052] Figure 6 It is a general design block diagram of a high-voltage pulse power supply in a simulation example of a method for calibrating a transient electric field sensor in a substation according to a second embodiment of the present invention;

[0053] Figure 7 It is an equivalent model diagram of a sharpening circuit in a simulation example of a substation transient electric field sensor calibration method according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0055] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0056] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0057] Example 1

[0058] Reference Figure 1-Figure 3 , which is the first embodiment of the present invention, provides a method for calibrating a transient electric field sensor in a substation, comprising:

[0059] S1: Place the electric field sensor in the transverse electromagnetic wave chamber, place the field strength probe in the upper part of the transverse electromagnetic wave chamber, and measure the electric field strength;

[0060] In an embodiment of the present application, measuring the electric field strength includes:

[0061] The electric field strength measured by the field strength probe is used as the field strength of the transverse electromagnetic wave chamber, and a coaxial load is used at the end of the transverse electromagnetic wave chamber to achieve impedance matching;

[0062] S2: Change the excitation source injected into the beginning of the transverse electromagnetic wave chamber and record the first fed power;

[0063] In the embodiment of the present application, the first feed power includes the electric field strength measured by the field strength probe at different frequencies and the feed power of the transverse electromagnetic wave chamber.

[0064] S3: Take out the field strength probe, put the electric field sensor into the position where the field strength probe was originally placed, and perform steady-state calibration;

[0065] In the embodiment of the present application, performing steady-state calibration includes:

[0066] Feed the first feed power into the transverse electromagnetic wave chamber, measure the output voltage of the electric field sensor, calculate the antenna coefficient, evaluate the radiation immunity of the substation transient electric field sensor, and complete the steady-state calibration;

[0067] S4: construct a transient calibration test loop, generate a high voltage pulse signal, and further generate a transient calibration test electric field environment;

[0068] Specifically, the transient calibration test circuit is composed of a high-voltage DC power supply, a first control circuit, a sharpening circuit, a test transmission line, a load resistor, a second control circuit, an oscilloscope and a light transmitter; the high-voltage DC power supply, the first control circuit, the sharpening circuit, the test transmission line and the load resistor are installed in an anechoic chamber.

[0069] In the embodiment of the present application, generating a high voltage pulse signal and further generating a transient calibration test electric field environment includes:

[0070] The working data of the high-voltage DC power supply is adjusted by the first control circuit, and a trigger signal is generated to control the sharpening circuit to generate a high-voltage pulse signal; the output high-voltage pulse signal is transmitted to the test transmission line to generate an electric field that meets the test requirements; the pulse is absorbed by the distributed terminal matching load resistor to avoid reflection;

[0071] Specifically, the single-phase 220V, 50Hz AC mains power is rectified and filtered into a 310V DC voltage, then frequency-converted into a 30kHz pulsating AC by an IGBT module, boosted to a 20kV pulsating high voltage by a high-frequency transformer, and stepped up for the first time by two groups of 8-fold voltage multipliers. The rectifier forms a DC high voltage with adjustable positive and negative voltages in the range of 0.4 to 150kV, which are charged to two groups of energy storage capacitors and sharpening capacitors respectively, discharged through a magnetically controlled mechanical stepping SF6 insulating gas switch, and then doubled for a second time to output an adjustable transient pulse high voltage of 0.8 to 300kV.

[0072] S5: Install the electric field sensor in a transient calibration test electric field environment to perform transient calibration;

[0073] In an embodiment of the present application, the electric field sensor is installed in a transient calibration test electric field environment, and the transient calibration includes:

[0074] The electric field sensor is installed in the anechoic chamber to measure the electric field generated in the anechoic chamber and the electric field data and waveform inside the test body, and the measured data is transmitted outside the anechoic chamber to display, read and store the data;

[0075] Specifically, the measured data is transmitted outside the anechoic chamber, and the data is displayed, read and stored through an oscilloscope.

[0076] like Figure 2 As shown, the electric field sensor includes a detector and a receiver, the detector includes a photocell, a power supply voltage stabilization module, an electric-to-optical circuit and an electric field sensing unit, and the receiver includes a power supply module, a semiconductor laser, an optical-to-electrical circuit and an electric field detection unit;

[0077] The power module, the laser, the power supply optical fiber, and the photocell are connected in sequence; the power module supplies power to the light-to-electricity circuit; the photocell supplies power to the electric-to-optical circuit through the power supply voltage stabilizing module; the light-to-electricity circuit and the electric-to-optical circuit are connected through the signal optical fiber, the electric field sensing unit is connected to the input end of the electric-to-optical circuit, and the electric field detection unit is connected to the output end of the light-to-electricity circuit.

[0078] It should be noted that, in this embodiment, the electric field is measured by the monopole antenna as a sensor, and the other parts are mainly used to realize laser power supply and optical fiber signal transmission.

[0079] like Figure 3 As shown, the electric field sensing unit includes a monopole antenna, a voltage-dividing capacitor, an impedance conversion circuit, an amplifying circuit, an optical transmitting circuit, an optical receiving circuit and a receiving device;

[0080] The monopole antenna, the impedance conversion circuit, and the amplifier circuit are connected in sequence; one end of the voltage-dividing capacitor is connected between the monopole antenna and the impedance conversion circuit, and the other end is grounded; the output end of the amplifier circuit is converted into an optical signal by the optical transmitting circuit, and then transmitted to the optical receiving circuit via the optical fiber, and then converted into an electrical signal again for transmission to the receiving device; the voltage received by the monopole antenna is divided by the voltage-dividing capacitor, input into the transmitting circuit, transmitted to the receiving circuit by the optical fiber, and received and displayed by the oscilloscope;

[0081] In another possible implementation, the output of the amplifier circuit is directly transmitted to the receiving device via a cable; in order to improve the sensitivity of the entire system, the monopole antenna can be appropriately lengthened or the voltage divider capacitor C value can be reduced to increase the original input signal. In this structural design, the value of the capacitor is variable, so that the dynamic range of the antenna system is adjustable.

[0082] When the monopole antenna is an electrically small antenna, the effective length is equal to half the physical length of the rod antenna; the calculation formula for the effective length of the rod antenna is as follows:

[0083]

[0084] Wherein, h represents the length of the antenna element; λ represents the wavelength corresponding to the operating frequency of the antenna element.

[0085] It should be noted that monopole antennas are generally equipped with an ideal ground plane and can be equivalent to dipole antennas. Generally, if the current distribution on the antenna surface is known, some characteristics of the antenna can be obtained by integrating the current. For electrically small monopole antennas, it is generally assumed that the current on the antenna surface is distributed according to the sine distribution, the current at the port far away from the ground plane is zero, and the current at the port close to the ground plane is at the maximum value. By analyzing the current state, the effective length of the rod antenna can be further calculated. The monopole antenna can be equivalent to a series connection of a capacitor and a resistor. Usually, the resistance value is relatively small and can be basically ignored. The electrically small antenna has a large input reactance. If the signal received by the monopole is directly connected to a 50-ohm system, only a small part of the data can be measured, and most of it is in the reactance, so a high input impedance field effect transistor is required to match it.

[0086] It should also be noted that in order to ensure that the power supply laser can work normally, this embodiment uses a constant current source circuit to drive. Changes in ambient temperature or semiconductor laser chip temperature can easily cause changes in the optical output power of the semiconductor laser. The function of the drive circuit to feedback the drive current is usually used, so that a stable optical output power can be obtained even if the temperature changes. There are many ways to implement a constant current source circuit, and it is common to use a voltage stabilizing chip as the main body of the constant current source.

[0087] Laser power cell LPC (Laser power cell) can convert the input laser energy of a specific wavelength into electrical energy and provide it to the load or sensor end, thereby realizing long-distance non-contact power supply. The laser power supply system consists of three parts: light source, optical fiber and power supply battery. The optical fiber power supply system is usually used in extremely harsh environments such as high electric field and high electromagnetic field. It is a safe and reliable non-contact power supply method.

[0088] The light source used in this embodiment is an optimized Fabry-Perot high-power multi-mode laser, with multiple transverse modes and longitudinal modes, and has the characteristics of low threshold and high power. It is further optimized and designed according to the characteristics of the laser battery, and has high reliability and high performance in combination with the full metallization sealing process. The center wavelength of the laser output light is around 905nm, which is suitable for supporting energy supply devices.

[0089] Laser energy batteries can ensure long service life through special active area material design, post-process semiconductor preparation technology based on micro-nano processing technology and sealed structure with high heat dissipation characteristics. Different types of batteries are sensitive to monochromatic light of different wavelengths, and different types of energy batteries can be selected according to specific application requirements.

[0090] The above is a schematic scheme of the substation transient electric field sensor calibration method of this embodiment. It should be noted that the technical scheme of the substation transient electric field sensor calibration system and the technical scheme of the substation transient electric field sensor calibration method above belong to the same concept, and the details of the technical scheme of the substation transient electric field sensor calibration system not described in detail in this embodiment can all be referred to the description of the technical scheme of the substation transient electric field sensor calibration method above.

[0091] The substation transient electric field sensor calibration system in this embodiment includes:

[0092] A field strength measurement module is used to place an electric field sensor in the transverse electromagnetic wave chamber, and place a field strength probe in the upper part of the transverse electromagnetic wave chamber to measure the electric field strength;

[0093] A feeding power recording module is used to change the excitation source injected into the beginning of the transverse electromagnetic wave chamber and record the first feeding power;

[0094] The steady-state calibration module is used to take out the field strength probe, put the electric field sensor into the position where the field strength probe was originally placed, and perform steady-state calibration;

[0095] A transient calibration environment generation module is used to construct a transient calibration test loop, generate a high-voltage pulse signal, and further generate a transient calibration test electric field environment;

[0096] The transient calibration module is used to install the electric field sensor in a transient calibration test electric field environment to perform transient calibration.

[0097] This embodiment also provides a computing device, which is applicable to the case of the substation transient electric field sensor calibration method, including:

[0098] Memory and processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the substation transient electric field sensor calibration method proposed in the above embodiment.

[0099] This embodiment further provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method for calibrating a transient electric field sensor in a substation as proposed in the above embodiment is implemented.

[0100] The storage medium proposed in this embodiment and the substation transient electric field sensor calibration method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0101] Example 2

[0102] Reference Figure 4-Figure 7 Table 1 is an embodiment of the present invention, which provides a method for calibrating a transient electric field sensor in a substation. In order to verify the beneficial effects of the present invention, a scientific demonstration is carried out through simulation experiments.

[0103] The steady-state calibration adopts the calibration method required by GB / T 17626.x standard. The TEM chamber, i.e. the transverse electromagnetic wave chamber, is a chamber that places a small test object and a cable in electric field radiation at the same time under the condition of very limited laboratory space to evaluate the radiation immunity of the test object. The general applicable frequency range is 0.01MHz to 200MHz. The TEM chamber generates a uniform field strength between the internal conductor (core board) and the outer shell (ground plate) to test the immunity of the ESA. The electric field strength in the TEM chamber is determined by the following equation:

[0104]

[0105] Where: E = electric field strength, unit is V / m; P = power input to the chamber, unit is W; Z = impedance of the chamber (50Ω); d = distance between the upper plate and the flat plate (core plate), unit is m.

[0106] Select an appropriate field strength probe and place it in the upper part of the TEM chamber. The field strength measured by the field strength probe is the field strength of the TEM chamber.

[0107] The end of the TEM cell uses a 50Ω coaxial load to achieve impedance matching. When the excitation is injected into the beginning of the TEM cell, there will be a uniform transverse electromagnetic traveling wave in the TEM cell with the same characteristics as the far-field electromagnetic wave in free space, thus better simulating the electromagnetic environment of free space.

[0108] In any cross section of the TEM cell, assuming that the input power is P, the input voltage is V, and the vertical distance between the core plate and the bottom plate is h, the uniform electric field strength in the available test area (less than or equal to h / 3) is:

[0109]

[0110] The TEM cell simulates the electromagnetic environment of free space, so the relationship between the electric field and the magnetic field conforms to the plane wave impedance relationship:

[0111]

[0112] The wave impedance in free space is a fixed value:

[0113]

[0114] Therefore, the relationship between the electric and magnetic fields is as follows:

[0115]

[0116] As long as the electric field strength is measured, the magnetic field strength can be calculated. Figure 4 As shown in the figure, the uniform transverse electromagnetic traveling wave generation system is composed of a signal generator, a power amplifier, a low-pass filter, a dual-channel directional coupler, a power meter and a TEM cell. The HI-6105 field intensity probe can measure the electric field intensity at a fixed position in the TEM cell at different frequencies. Change the excitation source and record the electric field intensity measured by the field intensity probe and the feed power of the TEM cell at different frequencies in the range of 100kHz to 200MHz.

[0117] Take out the field intensity probe, put the transient sensor in the same position of the TEM cell, feed the energy fed at different frequencies recorded previously into the TEM cell, measure the output voltage of the transient sensor, and then calculate the antenna coefficient. The test data of the electric field sensor is shown in Table 1.

[0118] Table 1 System measurement circuit 3dB bandwidth test

[0119]

[0120] In summary, the -3dB bandwidth of the electric field sensor meets 20kHz to 500kHz, so the requirement of the electric field simulation bandwidth of 100MHz is met.

[0121] Transient calibration is required to achieve a voltage of several kV within a few ns. Requirements include:

[0122] 1) Peak field strength: 5kV / m;

[0123] 2) Rising edge: ≤3.5ns (100MHz);

[0124] 3) Oscilloscope: analog bandwidth ≥ 500MHz, sampling rate ≥ 2GSa / s.

[0125] like Figure 5The figure shows the transient calibration test circuit diagram. The control circuit A is used to adjust the working data of the high-voltage DC power supply and generate a trigger signal to control the sharpening circuit to generate a high-voltage pulse signal. The output high-voltage pulse signal is transmitted to the test transmission line to generate an electric field that meets the test requirements in a certain space. The distributed terminal matching load resistor absorbs the pulse to avoid reflection.

[0126] The data exchange between the control system and the high-voltage pulse generator (high-voltage DC power supply + sharpening circuit) can be achieved by optical cable isolation.

[0127] Different types of sensors are installed in the test space to measure the electric and magnetic fields generated by the simulator and the electric and magnetic fields inside the test object. The analog data are transmitted to the outside of the anechoic chamber and displayed, read and stored by an oscilloscope.

[0128] The test system can be installed indoors or outdoors. When placed outdoors, the control and measurement equipment must be placed in a shielded facility to prevent strong electric field pulses from interfering with the control and measurement equipment.

[0129] Since the electric field of 5kV / m is required, and the effective use space of this set of metering equipment is 1 / 3 of the height H, it is necessary to first determine the height of the GIS electronic transformer, and then determine the DC high voltage value of the high voltage power supply. The high voltage power supply is designed to be adjustable within a certain range to meet different voltage requirements.

[0130] The single-phase 220V, 50Hz AC mains power is rectified and filtered into a 310V DC voltage, then frequency-converted into a 30kHz pulsating AC by an IGBT module, stepped up to a 20kV pulsating high voltage by a high-frequency transformer, stepped up for the first time by two groups of 8-fold voltage multipliers, and rectified to form a DC high voltage with adjustable positive and negative voltages in the range of 0.4 to 150kV. The two groups of energy storage capacitors and sharpening capacitors are charged respectively, and discharged through a magnetically controlled mechanical stepping SF6 insulating gas switch, and then doubled for a second time to output an adjustable transient pulse high voltage of 0.8 to 300kV.

[0131] The pulse power switch, high voltage regulation, feedback control (linear DC regulated power supply voltage feedback, high voltage feedback, current feedback circuit) and protection circuit are all controlled by a computer through optical fiber.

[0132] The overall design block diagram of high voltage pulse power supply is as follows: Figure 6 The equivalent model of the sharpening circuit is shown as Figure 7 As shown, Figure 7 In, C M is the energy storage capacitor; L M is the energy storage capacitor inductor; C tr is the sharpening capacitance; L tr is the sharpening inductor; K is the main switch; R is the load resistor.

[0133] The DC high voltage source is fed to the low inductance capacitor C M It is charged to U0 and then discharged to the load through the switch under triggering conditions. This is a standard RLC series discharge circuit.

[0134] When switch K is turned on at t=0, the circuit equation is:

[0135]

[0136] Where: C tr is the sharpening capacitor, which also has energy storage function; L is the total distributed inductance of the circuit; R is the sharpening resistor.

[0137] This formula is a second-order constant coefficient differential equation. Assume that the capacitance C M The voltage drop across is u c (t), using the initial condition I0 = 0, u c (0) = U0, three solutions can be obtained: underdamping, critical damping and overdamping.

[0138] Critical ratio α<1, underdamped condition;

[0139] α=1, which is the critical damping case;

[0140] α>1, overdamping condition;

[0141] When the critical ratio The current flowing through the forming resistor R is:

[0142]

[0143] The voltage drop across the load R is:

[0144]

[0145] This waveform is a double exponential pulse waveform.

[0146] Rise time

[0147] Decline time

[0148] FWHM

[0149] The choice of transmission line impedance will affect the signal strength received by the electric field sensor. The width of the upper and lower plates is closely related to the transmission line impedance, but it may reduce the sensitivity of the sensor. Assuming the aspect ratio is a / h, the width ratio of the upper and lower plates is w / a, W / a=2, the read impedance is 97Ω, (97 / 89)×115=125Ω, then the theoretical impedance R=115Ω; the actual impedance R=125Ω. After testing, the rising edge of the designed electric field sensor reaches 2.2514ns, which meets the requirement of rising edge ≤3.5ns (100MHz). The transient calibration of the entire system calibrates the -3dB bandwidth and rising edge parameters of the measurement system. The -3dB bandwidth of the electric field sensor meets 20kHz~500kHz, so it meets the requirement of 100MHz electric field simulation bandwidth. The rising edge of the transient calibration meets the requirement of rising edge ≤3.5ns (100MHz).

[0150] It should be noted that the above embodiments are only used to illustrate the technical solutions 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 solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for calibrating a transient electric field sensor in a substation, characterized in that: include: The electric field sensor is placed in the transverse electromagnetic wave chamber, and the field strength probe is placed in the upper part of the transverse electromagnetic wave chamber to measure the electric field strength; Change the excitation source injected into the beginning of the transverse electromagnetic wave chamber and record the first feeding power; Take out the field strength probe, put the electric field sensor into the position where the field strength probe was originally placed, and perform steady-state calibration; Construct a transient calibration test loop to generate a high-voltage pulse signal, and further generate a transient calibration test electric field environment; Install the electric field sensor in the transient calibration test electric field environment to perform transient calibration.

2. The method for calibrating a transient electric field sensor in a substation according to claim 1, characterized in that: The measuring electric field strength comprises: The electric field strength measured by the field strength probe is used as the field strength of the transverse electromagnetic wave chamber, and a coaxial load is used at the end of the transverse electromagnetic wave chamber to achieve impedance matching.

3. The method for calibrating a transient electric field sensor in a substation according to claim 2, characterized in that: The first feed-in power includes the electric field strength measured by the field strength probe at different frequencies and the feed-in power of the transverse electromagnetic wave chamber.

4. The method for calibrating a transient electric field sensor in a substation according to claim 3, characterized in that: The steady-state calibration comprises: The first feed power is fed into the transverse electromagnetic wave chamber, the output voltage of the electric field sensor is measured, the antenna coefficient is calculated, the radiation immunity of the substation transient electric field sensor is evaluated, and the steady-state calibration is completed.

5. The method for calibrating a transient electric field sensor in a substation according to claim 4, characterized in that: The generating of the high voltage pulse signal and further generating the transient calibration test electric field environment comprises: The working data of the high-voltage DC power supply is adjusted through the first control circuit, and a trigger signal is generated to control the sharpening circuit to generate a high-voltage pulse signal; the output high-voltage pulse signal is transmitted to the test transmission line to generate an electric field that meets the test requirements; the pulse is absorbed by the distributed terminal matching load resistor to avoid reflection.

6. The method for calibrating a transient electric field sensor in a substation according to claim 5, characterized in that: The electric field sensor is installed in a transient calibration test electric field environment, and the transient calibration is performed including: The electric field sensor is installed in the anechoic chamber to measure the electric field generated in the anechoic chamber and the electric field data and waveform inside the test body, and the measured data is transmitted outside the anechoic chamber to display, read and store the data; The electric field sensor comprises a detector and a receiver, wherein the detector comprises a photocell, a power supply voltage stabilization module, an electric-to-optical circuit and an electric field sensing unit, and the receiver comprises a power supply module, a semiconductor laser, an optical-to-electrical circuit and an electric field detection unit; The power module, laser, power supply optical fiber, and photocell are connected in sequence; the power module supplies power to the light-to-electricity circuit; the photocell supplies power to the electric-to-light circuit through a power supply voltage stabilizing module; the light-to-electricity circuit and the electric-to-light circuit are connected through a signal optical fiber, the electric field sensing unit is connected to the input end of the electric-to-light circuit, and the electric field detection unit is connected to the output end of the light-to-electricity circuit.

7. The method for calibrating a transient electric field sensor in a substation according to claim 6, characterized in that: The electric field sensing unit includes a monopole antenna, a voltage-dividing capacitor, an impedance conversion circuit, an amplifying circuit, a light transmitting circuit, a light receiving circuit and a receiving device; The monopole antenna, the impedance conversion circuit, and the amplifier circuit are connected in sequence; one end of the voltage-dividing capacitor is connected between the monopole antenna and the impedance conversion circuit, and the other end is grounded; the output end of the amplifier circuit is converted into an optical signal by the optical transmitting circuit, and then transmitted to the optical receiving circuit via the optical fiber, and then converted into an electrical signal again for transmission to the receiving device; the voltage received by the monopole antenna is divided by the voltage-dividing capacitor, input into the transmitting circuit, transmitted to the receiving circuit by the optical fiber, and received and displayed by the oscilloscope; When the monopole antenna is an electrically small antenna, the effective length is equal to half the physical length of the rod antenna; the calculation formula for the effective length of the rod antenna is as follows: Wherein, h represents the length of the antenna element; λ represents the wavelength corresponding to the operating frequency of the antenna element.

8. A system using the substation transient electric field sensor calibration method according to any one of claims 1 to 7, characterized in that: include: A field strength measurement module is used to place an electric field sensor in the transverse electromagnetic wave chamber, and place a field strength probe in the upper part of the transverse electromagnetic wave chamber to measure the electric field strength; A feeding power recording module is used to change the excitation source injected into the beginning of the transverse electromagnetic wave chamber and record the first feeding power; The steady-state calibration module is used to take out the field strength probe, put the electric field sensor into the position where the field strength probe was originally placed, and perform steady-state calibration; A transient calibration environment generation module is used to construct a transient calibration test loop, generate a high-voltage pulse signal, and further generate a transient calibration test electric field environment; The transient calibration module is used to install the electric field sensor in a transient calibration test electric field environment to perform transient calibration.

9. A computing device comprising: Memory and processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the substation transient electric field sensor calibration method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the substation transient electric field sensor calibration method according to any one of claims 1 to 7.

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