A platform and method for high power electromagnetic pulse loading of power equipment in an energized state

Abstract

The application provides a strong electromagnetic pulse loading platform and method in the power-on state of an electric power device, and aims to solve the technical problem that the internal circuit insulation withstand voltage and power capacity of a strong electromagnetic pulse source cannot withstand high power frequency voltage. The loading platform is characterized in that one end of three high-voltage coupling capacitors is connected to three phase lines of three-phase transmission cables respectively, and the other end is connected together, and an equivalent "zero potential" point is formed through the 120-degree phase difference of three-phase power frequency voltage. The loading method is characterized in that the equivalent "zero potential" point is constructed, the threat of power frequency voltage to the internal circuit insulation withstand voltage and power capacity of a pulse source in the power-on state is overcome, the efficient coupling of a strong electromagnetic pulse source output and a to-be-tested electric power device is realized while providing a reference phase for the superposition of nanosecond pulses on millisecond power frequency signals, and the construction of a strong electromagnetic pulse effect test method and platform for the to-be-tested electric power device in the power-on state is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to strong electromagnetic pulses, and in particular to a strong electromagnetic pulse loading platform and method in the power-on state of power equipment. BACKGROUND

[0002] Strong electromagnetic pulses generally refer to transient electromagnetic radiation environments with an electric field strength greater than 1 kV / m. According to the frequency band and energy, it can be divided into high-altitude electromagnetic pulses (HEMP), high-power microwave (Narrowband and Wideband), lightning, and other environments. Power equipment is an important part of the national economy and is also the premise and foundation for the normal operation of various power electronic devices. Lightning and nanosecond pulse impact voltage, including high-altitude electromagnetic pulses, are the main strong electromagnetic pulse environments that affect the safe and stable operation of power equipment. Therefore, in recent years, China has gradually increased its attention to the effects of key power equipment under strong electromagnetic pulses, and has proposed the need for effect test research on key power equipment under the action of strong electromagnetic pulses, so as to obtain the strong electromagnetic pulse effect threshold and failure mechanism of power equipment, and provide data support for the survival capability evaluation of power equipment under strong electromagnetic pulses.

[0003] At present, there is no mature method and test platform for high-altitude electromagnetic pulse effect test of power equipment, and there is also a lack of complete fault diagnosis and fine measurement methods. The HEMP pulse source index requirements are not as clear as lightning, operating overvoltage, and other pulse sources. Only the short-circuit current waveform index on the cable is given in the relevant standards. However, in the actual test process, the port characteristics of different test objects differ greatly, making the pulse source output vary with the test object, and the potential-sensitive test objects such as transformer windings cannot be tested according to the standard method.

[0004] Power equipment is different from other electronic equipment. In the normal working state, it withstands tens of kilovolts or even thousands of volts of power frequency voltage, which may cause the weak points existing in the equipment to break down and form a power frequency current channel under the synergistic action of strong electromagnetic pulses, thereby causing a short circuit fault or even burning of the equipment. Therefore, special attention should be paid to the strong electromagnetic pulse effect test of power equipment in the power-on state. The coupling and decoupling device used in the existing lightning impulse test has problems such as unsuitable coupling and decoupling network parameters under nanosecond-level strong electromagnetic pulses such as high-altitude electromagnetic pulses, and the wiring method easily causes the rising edge of the nanosecond-level pulse waveform to become slow. In addition, there are two key problems when injecting three-phase common mode to power equipment. First, the current through the high-voltage coupling capacitor may cause a three-phase short circuit fault, causing the switch to trip or even a power failure. Second, the power frequency voltage applied to the pulse current injection source at the pulse injection point may exceed the withstand voltage and power of the output resistance of the pulse current injection source, causing insulation failure or even burning of the pulse current injection source. SUMMARY

[0005] The present application aims to solve the technical problem that the insulation withstand voltage and power capacity of the internal circuit of the strong electromagnetic pulse source cannot withstand the high voltage of the power frequency, and to provide a strong electromagnetic pulse loading platform and method in the power-on state of the power equipment.

[0006] To achieve the above-mentioned purpose, the technical concept provided by the present application is as follows:

[0007] Based on the construction of the equivalent "zero potential" point, the threat of the high voltage of the power frequency to the insulation withstand voltage and power capacity of the internal circuit of the pulse source in the power-on state is overcome, while providing a reference phase for the superposition of the nanosecond pulse on the millisecond power frequency signal, the efficient coupling of the strong electromagnetic pulse source output and the power equipment to be tested is realized, and then the construction of the strong electromagnetic pulse effect test method and platform of the power equipment in the power-on state is realized.

[0008] The technical solution of the present application is as follows:

[0009] A strong electromagnetic pulse loading platform in the power-on state of power equipment, characterized in that it comprises a strong electromagnetic pulse source, a three-phase transmission line experiment platform and three high-voltage coupling capacitors;

[0010] The three-phase transmission line experiment platform comprises a power frequency power supply, a step-up transformer, a first circuit breaker, a three-phase transmission cable, a second circuit breaker, a step-down transformer and a load connected in sequence;

[0011] The three-phase transmission cable is connected with the power equipment to be tested, for providing normal working voltage to the power equipment to be tested through the power frequency power supply, the step-up transformer and the first circuit breaker, and providing port impedance to the power equipment to be tested through the load, the step-down transformer and the three-phase transmission cable;

[0012] The first circuit breaker is used to realize the on-off between the power frequency power supply and the three-phase transmission cable;

[0013] The second circuit breaker is used to realize the on-off between the load and the three-phase transmission cable;

[0014] The capacitance of the high-voltage coupling capacitor is determined according to the environment of the strong electromagnetic pulse, and the withstand voltage value is determined according to the highest voltage output by the strong electromagnetic pulse source;

[0015] One end of each of the three high-voltage coupling capacitors is connected to the three phase lines of the three-phase transmission cable, and the other end of each of the three high-voltage coupling capacitors is connected together, for forming an equivalent "zero potential" point through the 120° phase difference of the three-phase power frequency voltage;

[0016] The high-voltage output end of the strong electromagnetic pulse source is directly connected with the equivalent "zero potential" point, and the strong electromagnetic pulse interference signal in the power-on state is loaded on the port of the power equipment to be tested by triggering the strong electromagnetic pulse source.

[0017] Further, the voltage measurement probe, the first current sensor, the first voltage sensor and the oscilloscope are further included.

[0018] The voltage measurement probe is used to measure the potential of the equivalent "zero potential" point to ensure the reliability of the equivalent "zero potential" point.

[0019] The first current sensor is used to measure the current flowing through the output port of the strong electromagnetic pulse source, and the first voltage sensor is used to measure the voltage of the output port of the strong electromagnetic pulse source, so as to ensure the correct connection of the high-voltage output end of the strong electromagnetic pulse source and the equivalent "zero potential" point through the current measured by the first current sensor and the voltage measured by the first voltage sensor.

[0020] The output ends of the voltage measurement probe, the first current sensor and the first voltage sensor are used to connect the input end of the oscilloscope.

[0021] Further, the second current sensor and the second voltage sensor are further included.

[0022] The second current sensor and the second voltage sensor are respectively used to measure the current and the voltage at the specified position of the power equipment to be tested.

[0023] The output ends of the second current sensor and the second voltage sensor are used to connect the input end of the oscilloscope.

[0024] Based on the strong electromagnetic pulse loading platform in the power-on state of the power equipment, the application further provides a strong electromagnetic pulse loading method in the power-on state of the power equipment, and the speciality thereof lies in comprising the following steps.

[0025] 1】selecting a high-voltage coupling capacitor

[0026] The capacitance value is determined according to the environment of the strong electromagnetic pulse, the withstand voltage value of the capacitor is determined according to the highest voltage output by the strong electromagnetic pulse source, and three capacitors meeting the requirements and having the same specifications are selected as the high-voltage coupling capacitors according to the determined capacitance value and withstand voltage value.

[0027] 2】constructing an equivalent "zero potential" point

[0028] 2.1】building a three-phase transmission line experimental platform; the three-phase transmission line experimental platform comprises a power frequency power supply, a step-up transformer, a first circuit breaker, a three-phase transmission cable, a second circuit breaker, a step-down transformer and a load which are connected in sequence.

[0029] 2.2】The three-phase transmission cable is disconnected from the power frequency power supply by the first circuit breaker. One end of each of the three high-voltage coupling capacitors is connected to each phase line of the three-phase transmission cable, and the other ends of the three high-voltage coupling capacitors are connected together, so that the connection point of the three high-voltage coupling capacitors forms an equivalent "zero potential" point.

[0030] 3. Connect the output port of the high-power electromagnetic pulse source directly to the equivalent "zero potential" point;

[0031] 4. Achieving the loading of strong electromagnetic pulses under powered conditions

[0032] 4.1 Connect the electrical equipment under test to a three-phase power transmission cable;

[0033] 4.2】Connect the three-phase transmission cable to the power frequency power supply through the first circuit breaker;

[0034] 4.3 Turn on the power frequency power supply to connect the three-phase transmission cable to the normal power frequency voltage; trigger the strong electromagnetic pulse source to load the strong electromagnetic pulse interference signal on the port of the power equipment under test under the power-on state.

[0035] Furthermore, step 1 specifically involves:

[0036] 1.1】Measuring the open-circuit voltage U of a strong electromagnetic pulse source o and short-circuit current I s And according to the open circuit voltage U o and short-circuit current I s Calculate the internal resistance R of a strong electromagnetic pulse source s ;

[0037] 1.2】The frequency domain transformation of the output current of the strong electromagnetic pulse source is performed to calculate the upper frequency limit f of the main energy concentration band of the strong electromagnetic pulse signal. H ;

[0038] 1.3】Set the capacitor value C so that f H Equivalent impedance at frequency Negligible, i.e.

[0039] 1.4】Set the capacitor's withstand voltage U according to the following formula. c-pulse :

[0040] U c-pulse =k*U m

[0041] Among them, U m The maximum voltage output by the strong electromagnetic pulse source is k, which is the safety margin factor, k = 1.05 to 1.35;

[0042] 1.5】According to the capacitance value C obtained in step 1.3】 and the withstand voltage value U of the capacitor obtained in step 1.4】 c-pulse Three capacitors meeting the requirements and having the same specifications are selected as the high-voltage coupling capacitors.

[0043] Further, in step 1.3】, let Then the capacitance value

[0044] In step 1.4】, k = 1.1.

[0045] Further, step 2】 further comprises step 2.3】: measuring the potential of the equivalent "zero potential" point by a voltage measurement probe to ensure that the equivalent "zero potential" point is reliable.

[0046] Further, step 3】 is specifically:

[0047] The high-voltage output end of the strong electromagnetic pulse source is directly connected to the equivalent "zero potential" point, and the length of the connecting cable is the shortest under the premise of ensuring the insulation safety distance of the pulse source and the three-phase power cable.

[0048] Further, step 3】 further comprises: connecting the three-phase power cable to the power frequency power source through the first circuit breaker, and then measuring the current and voltage flowing through the output port of the strong electromagnetic pulse source through the first current sensor and the first voltage sensor respectively, if the current of the output port of the strong electromagnetic pulse source is less than 0.5A, the voltage of the output port of the strong electromagnetic pulse source is less than 25V, and the power frequency power source does not trip, it indicates that the connection between the high-voltage output end of the strong electromagnetic pulse source and the equivalent "zero potential" point is correct.

[0049] Further, step 4】 is specifically:

[0050] 4.1】 disconnect the three-phase power cable from the power frequency power source through the first circuit breaker, and connect the to-be-tested power equipment on the three-phase power cable; set the second voltage sensor and the second current sensor for measuring the voltage and current at the specified position of the to-be-tested power equipment respectively, and connect the signal lines of the current sensor and the voltage sensor to the oscilloscope;

[0051] 4.2】 connect the three-phase power cable to the power frequency power source through the first circuit breaker;

[0052] 4.3】 turn on the power frequency power source, and judge whether the voltage applied to the to-be-tested power equipment is the normal working voltage through the voltage signal on the oscilloscope; when the voltage applied to the to-be-tested power equipment is the normal working voltage, the phase of the power frequency voltage is detected, the trigger time of the strong electromagnetic pulse source is specified, and the superposition of the strong electromagnetic pulse interference signal on the specified phase of the power frequency voltage is performed.

[0053] The beneficial effects of the present application compared with the prior art are:

[0054] 1. The strong electromagnetic pulse loading platform under the power-on state of the power equipment, wherein three phase lines of a three-phase power cable are connected with one high-voltage coupling capacitor with the same specification respectively, the other ends of the high-voltage coupling capacitors are connected together to form an equivalent zero potential point; the output end of a strong electromagnetic pulse source is connected with the equivalent zero potential point, and the strong electromagnetic pulse signal can be loaded on the power equipment connected with the three-phase power cable by triggering the strong electromagnetic pulse source, so that the strong electromagnetic pulse injection test under the normal working state of the power equipment is realized, the problem that the internal circuit insulation withstand voltage and power capacity of the strong electromagnetic pulse source cannot withstand the power frequency high voltage is solved, the efficient coupling between the output of the strong electromagnetic pulse source and the power equipment under test is realized, and the strong electromagnetic pulse effect phenomenon and threshold data of the power equipment under test under the real working condition are obtained.

[0055] 2. The strong electromagnetic pulse loading platform under the power-on state of the power equipment, wherein the potential of the equivalent zero potential point is measured by a voltage measurement probe, so that the reliability of the equivalent zero potential point is ensured; the current flowing through the output port of the strong electromagnetic pulse source and the voltage of the output port of the strong electromagnetic pulse source are measured by a first current sensor and a first voltage sensor respectively, so that the wiring between the high-voltage output end of the strong electromagnetic pulse source and the equivalent zero potential point is correct, and the safety and reliability of the strong electromagnetic pulse loading system experiment under the power-on state of the power equipment are improved.

[0056] 3. The strong electromagnetic pulse loading method under the power-on state of the power equipment, wherein the equivalent zero potential characteristic is innovatively provided, the wiring connection mode of the safe potential for the output circuit of the strong electromagnetic pulse source is provided, the strong electromagnetic pulse current or voltage is injected into the port of the power equipment under test under the power-on state, and the strong electromagnetic pulse effect loading method is realized; by the method, the threat of the power frequency high voltage under the power-on state to the internal circuit insulation withstand voltage and power capacity of the pulse source can be overcome, the reference phase for the superposition of the nanosecond pulse on the millisecond power frequency signal is provided, the efficient coupling between the output of the strong electromagnetic pulse source and the power equipment under test is facilitated, the construction of the strong electromagnetic pulse effect test method and platform under the power-on state of the power equipment is beneficial, and the test acquisition of the strong electromagnetic pulse effect threshold and failure mechanism of the power equipment is of great significance.

[0057] 4. The strong electromagnetic pulse loading method under the power-on state of the power equipment, which has the characteristics of strong universality and wide application, and is suitable for the strong electromagnetic pulse effect test research of typical power equipment. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 It is a structural schematic view of the strong electromagnetic pulse loading platform under the power-on state of the power equipment.

[0059] Figure 2 Equivalent "zero potential" point wiring diagram in the application;

[0060] Figure 3 Short-circuit current time-domain waveform diagram of the strong electromagnetic pulse source output in the embodiment of the application, wherein (a) is the overall waveform diagram, and (b) is the pulse front waveform diagram;

[0061] Figure 4 Short-circuit current frequency-domain waveform and upper limit frequency acquisition diagram of the strong electromagnetic pulse source output in the embodiment of the application;

[0062] Figure 5 Voltage change curve diagram of the output port of the strong electromagnetic pulse source in the embodiment of the application;

[0063] Figure 6 Current change curve diagram of the three high-voltage coupling capacitors in the embodiment of the application;

[0064] Figure 7 Superposition diagram of the high-altitude electromagnetic pulse at the specified phase of the power frequency voltage in the embodiment of the application. DETAILED DESCRIPTION

[0065] In order to make the advantages and characteristics of the application more clear, the application will be further described in detail below in combination with the drawings and specific embodiments.

[0066] In the embodiment, the power equipment 10 to be tested is a three-phase 10kV oil-immersed distribution transformer, and the injected strong electromagnetic pulse source 1 is a high-altitude electromagnetic pulse (HEMP) current injection source. For the high-altitude electromagnetic pulse effect test of the transformer, the oil-immersed distribution transformer is set to be in the energized working state, and a three-phase 10kV power transmission line effect test platform is built. The distribution transformer port is tested by using the high-altitude electromagnetic pulse injection method, the voltage and current waveforms of the distribution transformer port are monitored through the resistance-capacitance voltage divider and the current sensor, and then the transformer effect phenomenon and damage threshold data are obtained, thereby providing a basis for the protection and reinforcement design of the distribution transformer to cope with the high-altitude electromagnetic pulse environment.

[0067] As Figure 1As shown, a strong electromagnetic pulse loading platform in the power-on state of a power device includes a strong electromagnetic pulse source 1, a three-phase transmission line experiment platform, three high-voltage coupling capacitors 2, a voltage measurement probe, a first current sensor 11, a second current sensor, a first voltage sensor 12, a second voltage sensor, and an oscilloscope 13. The three-phase transmission line experiment platform is a traditional three-phase transmission line platform, which is used to provide the voltage and port impedance required by the power device 10 under normal working conditions, and uses a strong electromagnetic pulse injection method to test the power device port to obtain the strong electromagnetic pulse effect threshold and damage of the power device under normal working conditions. It includes a power frequency power supply 3, a step-up transformer 4, a first circuit breaker 5, a three-phase transmission cable 6, a second circuit breaker 7, a step-down transformer 8, and a load 9 connected in turn. Among them, the power device 10 under test is connected to the three-phase transmission cable 6, which is used to provide normal working voltage to the power device 10 under test through the power frequency power supply 3, the step-up transformer 4 and the three-phase transmission cable 6, and to provide port impedance to the power device 10 under test through the load 9, the step-down transformer 8 and the three-phase transmission cable 6. The first circuit breaker 5 is used to realize the on-off between the power frequency power supply 3 and the three-phase transmission cable 6, and the second circuit breaker 7 is used to realize the on-off between the load 9 and the three-phase transmission cable 6. As shown in FIG. 1, the power device 10 under test is connected to the three-phase transmission cable 6 through the first circuit breaker 5 and the second circuit breaker 7. Figure 2As shown, one end of the three high-voltage coupling capacitors 2 is connected to the three phase lines of the three-phase power cable 6, respectively, and is marked as C-A, C-B, and C-C; the other end of the three high-voltage coupling capacitors 2 is connected together, and the connection point is marked as O, which is used to form an equivalent "zero potential" point by the 120° phase difference of the three-phase power frequency voltage. The high-voltage output end of the strong electromagnetic pulse source 1 is directly connected to the equivalent "zero potential" point, and by triggering the strong electromagnetic pulse source 1, a strong electromagnetic pulse current or voltage is injected into the port of the power equipment to be tested 10 in the powered state, so as to realize the loading of the strong electromagnetic pulse interference signal at the port of the power equipment to be tested 10. The output ends of the voltage measurement probe, the first current sensor 11, the first voltage sensor 12, the second current sensor, and the second voltage sensor are used to connect the input ends of the oscilloscope 13, and the measured current and voltage are observed through the oscilloscope 13. The voltage measurement probe is used to measure the potential of the equivalent "zero potential" point to ensure that the equivalent "zero potential" point is reliable. The first current sensor 11 is used to measure the current flowing through the output port of the strong electromagnetic pulse source 1, and the first voltage sensor 12 is used to measure the voltage of the output port of the strong electromagnetic pulse source 1. By observing the current measured by the first current sensor 11 and the voltage measured by the first voltage sensor 12, it can be judged whether the connection between the high-voltage output end of the strong electromagnetic pulse source 1 and the equivalent "zero potential" point is correct. In this embodiment, the first voltage sensor 12 adopts a resistance-capacitance voltage divider. When the first current sensor 11 and the resistance-capacitance voltage divider measure the current flowing through the output port of the strong electromagnetic pulse source 1 and the voltage of the output port of the strong electromagnetic pulse source 1 (i.e. the voltage on the output resistor of the strong electromagnetic pulse source 1), if the current flowing through the output port of the strong electromagnetic pulse source 1 and the voltage of the output port of the strong electromagnetic pulse source 1 are both close to zero, and the power frequency power supply 3 does not trip, it indicates that the connection between the high-voltage output end of the strong electromagnetic pulse source 1 and the equivalent "zero potential" point is correct. In this application, the current close to zero at the output port of the strong electromagnetic pulse source 1 usually refers to less than 0.5 A, and the voltage close to zero at the output port of the strong electromagnetic pulse source 1 usually refers to less than 25 V. The second current sensor and the second voltage sensor are used to measure the current and voltage at the specified position of the power equipment to be tested 10, respectively. Specifically, the positions for measuring current and voltage are different for different power equipment to be tested 10 or different test settings. For example, for a transformer, if the test only focuses on the impedance response of the transformer, only the current and voltage at the port of the transformer need to be measured. However, if the potential distribution of the winding inside the transformer is to be focused on, the voltage at different positions inside the winding of the transformer needs to be measured. Therefore, the positions of the second current sensor and the second voltage sensor need to be set according to the actual situation, i.e. according to the position of interest of the power equipment to be tested 10, and combined with the test purpose. In this embodiment, they are set at the input port of the device to be tested, for monitoring the current flowing through the device to be tested and the port voltage.

[0068] Based on the aforementioned strong electromagnetic pulse loading platform for power equipment under energized conditions, this invention also provides a strong electromagnetic pulse loading method for power equipment under energized conditions, specifically including the following steps:

[0069] 1. Select a high-voltage coupling capacitor 2.

[0070] 1.1】Measure the open-circuit voltage U of the strong electromagnetic pulse source 1 o and short-circuit current I s And calculate the internal resistance R of the strong electromagnetic pulse source 1 according to the following formula. s :

[0071] R s =U o / I s ;

[0072] By performing a frequency domain transformation on the output current of strong electromagnetic pulse source 1, the upper frequency limit f of the main energy concentration band of the strong electromagnetic pulse signal can be calculated. H ;

[0073] According to the requirements of GJB8848-2016 standard, a high-altitude electromagnetic pulse current injection source must meet the following requirements: short-circuit output is a double exponential current waveform, rise time 20ns±15%, half-width at half-maximum (FWHM) 500ns~550ns, and peak current ≥5kA. Based on the above standard, the source resistance R of the high-altitude electromagnetic pulse current injection source in this embodiment is... s =63Ω, with a maximum output peak voltage of 400kV. To demonstrate the performance of the high-altitude electromagnetic pulse current injection source, such as... Figure 3 As shown, the time-domain waveform of the short-circuit current output from the high-altitude electromagnetic pulse current injection source is presented, where, Figure 3 (a) in the diagram is the overall waveform. Figure 3 (b) in the diagram is the waveform of the pulse leading edge; through Figure 3 The waveform diagrams show a high degree of overlap among the three tests, indicating good repeatability and demonstrating the high output stability of the high-altitude electromagnetic pulse current injection source in this invention. Generally, the high-frequency corner frequency is taken as the upper frequency limit of the main energy concentration band, such as... Figure 4 The diagram shows the frequency domain waveform of the short-circuit current output by the strong electromagnetic pulse source 1 and the upper frequency limit. The frequency corresponding to the intersection of the low-frequency extension line and the high-frequency fitting line is 4MHz, which is the upper frequency limit f of the main energy concentration band of the strong electromagnetic pulse signal in this embodiment. H =4MHz.

[0074] 1.2】Set the capacitance value C so that f H Equivalent impedance at frequency Negligible, i.e. Generally, it can be ordered Therefore, it is necessary to adjust the capacitance value. In this embodiment, f H = 4 MHz, so the capacitance C should be greater than or equal to 40 nF.

[0075] 1.3】Determine the voltage withstand value U c-pulse of the capacitor according to the following formula:

[0076] U c-pulse = k * U m

[0077] where U m is the maximum voltage output by the strong electromagnetic pulse source 1, and k is a safety margin coefficient, k = 1.05-1.35, and preferably the safety margin coefficient k is generally 1.1.

[0078] In this embodiment, when the high-altitude electromagnetic pulse current injection source outputs a short-circuit current of 5 kA, the corresponding maximum voltage U m output by the strong electromagnetic pulse source 1 is 315 kV, and an appropriate safety margin coefficient is taken to make the voltage withstand value U c-pulse of the capacitor 350 kV.

[0079] 1.4】Select three capacitors that meet the requirements and have the same specifications as the high-voltage coupling capacitor 2 according to the capacitance C determined in step 1.2】and the voltage withstand value U c-pulse of the capacitor determined in step 1.3】.

[0080] Since the voltage withstand value U c-pulse of the capacitor in this embodiment is 350 kV and the capacitance C is greater than or equal to 40 nF, a metallized film capacitor with a DC voltage withstand value of 150 kV and a capacitance of 120 nF ± 10% can be selected. According to the estimation that the AC voltage withstand value is about 3 times the DC voltage withstand value (generally 3-5 times), the AC voltage withstand value U c-pulse is about 450 kV, so the above-mentioned metallized film capacitor with the specified specifications selected in this embodiment meets the requirements.

[0081] 2】Construct an equivalent "zero potential" point

[0082] 2.1】Build a three-phase 10 kV transmission line experimental platform

[0083] The three-phase 10kV transmission line experimental platform comprises, in sequence, a power frequency power supply 3, a power supply filter, a 10kV step-up transformer 4, a first circuit breaker 5, a three-phase transmission cable 6, a second circuit breaker 7, a 10kV step-down transformer 8 and a load 9. The three-phase transmission cable 6 is fixed by a wire pole, and a power equipment to be tested 10 is connected to the three-phase transmission cable 6, for providing normal working voltage to the power equipment to be tested 10 through the power frequency power supply 3, the step-up transformer 4 and the three-phase transmission cable 6, and for providing port impedance to the power equipment to be tested 10 through the load 9, the step-down transformer 8 and the three-phase transmission cable 6. The power supply filter is used for filtering the power frequency power supply 3; the first circuit breaker 5 is used for realizing the on-off between the power frequency power supply 3 and the three-phase transmission cable 6, and the second circuit breaker 7 is used for realizing the on-off between the load 9 and the three-phase transmission cable 6.

[0084] 2.2】Disconnect the three-phase transmission cable 6 from the power frequency power supply 3 through the first circuit breaker 5, and connect one end of the three high-voltage coupling capacitors 2 selected in step 1 to three phase lines of the three-phase transmission cable 6 respectively under the premise of safety, and mark them as C-A, C-B and C-C respectively; connect the other end of the three high-voltage coupling capacitors 2 together and mark them as O, and the O point is the equivalent “zero potential” point by using the 120° phase difference of the three-phase power frequency voltage.

[0085] 2.3】Considering the error in the process of determining the capacitance of the high-voltage coupling capacitor 2, the application measures the potential of the O point through a voltage measurement probe after the connection of the three high-voltage coupling capacitors 2 is completed, to ensure that the equivalent “zero potential” point is reliable.

[0086] At the same time, the voltage of the output port of the strong electromagnetic pulse source 1 and the current flowing through the output port of the strong electromagnetic pulse source 1 are measured by the resistance-capacitance voltage divider and the first current sensor 11, as shown in Figure 5 , which is a voltage change curve diagram of the output port of the strong electromagnetic pulse source 1. The voltage value of the output port of the strong electromagnetic pulse source 1 is the potential of the equivalent “zero potential” point, which can be seen to be almost zero. Since the current flowing through the output port of the strong electromagnetic pulse source 1 is the sum of the currents of the three high-voltage coupling capacitors 2, as shown in Figure 6 , which is a current change curve diagram of the three high-voltage coupling capacitors 2, it can be seen from the diagram that the step-up transformer 4 is a 0.4 / 10kV transformer, and its transformation ratio is 10 / 0.4=25. The high-voltage side current of the step-up transformer 4 is about 0.4A, and the low-voltage side current is 0.4 / 25=0.016A, which is about 20mA. That is, the corresponding high-voltage coupling capacitor 2 current is about 20mA when converted to the power frequency power supply 3 end through the step-up transformer 4, which belongs to the normal working range of the protection switch. Therefore, the equivalent “zero potential” point is reliable, and the line connection is normal.

[0087] 3】Connect the high-voltage output of the strong electromagnetic pulse source 1 with the equivalent "zero potential" point

[0088] 3.1】Connect the high-voltage output of the strong electromagnetic pulse source 1 with the equivalent "zero potential" point directly, and in order to avoid waveform rising edge distortion, the length of the connecting cable should be as short as possible under the premise of ensuring the insulation safety distance of the strong electromagnetic pulse source 1 and the three-phase power cable 6.

[0089] 3.2】Check whether the connection between the high-voltage output of the strong electromagnetic pulse source 1 and the equivalent "zero potential" point is correct. First, make the three-phase power cable 6 communicate with the power frequency power supply 3 through the first circuit breaker 5, then measure the current and voltage of the output port of the strong electromagnetic pulse source 1 through the first current sensor 11 and the resistance-capacitance voltage divider respectively, if the current and voltage of the output port of the strong electromagnetic pulse source 1 are both close to zero, and the power frequency power supply 3 does not trip, it indicates that the connection between the high-voltage output of the strong electromagnetic pulse source 1 and the equivalent "zero potential" point is correct; in the present application, the current close to zero at the output port of the strong electromagnetic pulse source 1 usually refers to less than 0.5A, and the voltage close to zero at the output port of the strong electromagnetic pulse source 1 usually refers to less than 25V.

[0090] 4】Realize the loading of strong electromagnetic pulse in the power-on state

[0091] 4.1】Disconnect the three-phase power cable 6 from the power frequency power supply 3 through the first circuit breaker 5, and connect the to-be-tested power equipment 10 on the three-phase power cable 6 under the premise of safety.

[0092] At the same time, set the second voltage sensor and the second current sensor at the input port of the to-be-tested equipment, and connect the signal lines at the output ends of the second voltage sensor and the second current sensor to the input ends of the oscilloscope 13.

[0093] 4.2】Make the three-phase power cable 6 communicate with the power frequency power supply 3 through the first circuit breaker 5.

[0094] 4.3】Turn on the power frequency power supply 3 to make the three-phase power cable 6 connect to the normal power frequency voltage, and judge whether the voltage applied to the to-be-tested power equipment 10 is the normal working voltage through the voltage signal on the oscilloscope 13, in other embodiments of the present application, for example, some power equipment (linear impedance) can also judge whether the voltage applied to the to-be-tested power equipment 10 is the normal working voltage through the current signal. For example Figure 7As shown in the figure, the solid line represents the output pulse of the strong electromagnetic pulse source 1, the short dashed line represents the power frequency voltage on the three-phase power cable 6, i.e. the power frequency voltage on the power equipment 10 to be tested, and the long dashed line represents the power frequency superimposed pulse voltage waveform at the port of the power equipment 10 to be tested, i.e. the superposition of the strong electromagnetic pulse interference signal on the specified phase of the power frequency voltage; when the voltage applied to the power equipment 10 to be tested is the normal working voltage, the phase of the power frequency voltage is detected, the trigger time of the strong electromagnetic pulse source 1 is specified, and the superposition of the strong electromagnetic pulse interference signal on the specified phase of the power frequency voltage is performed.

[0095] The above description is only used to illustrate the technical solutions of the present application, and is not a limitation. For ordinary skilled persons in the art, the specific technical solutions described in the above embodiments can be modified, or some technical features can be replaced by equivalents, and these modifications or replacements do not change the essence of the corresponding technical solutions out of the scope of the technical solutions protected by the present application.

Claims

1. A high-intensity electromagnetic pulse loading platform for power equipment under energized conditions, characterized in that: It includes a strong electromagnetic pulse source (1), a three-phase transmission line experimental platform, and three high-voltage coupling capacitors (2); The three-phase transmission line test platform includes a power frequency power supply (3), a step-up transformer (4), a first circuit breaker (5), a three-phase transmission cable (6), a second circuit breaker (7), a step-down transformer (8), and a load (9) connected in sequence. The three-phase power transmission cable (6) is connected to the power device under test (10), which is used to provide normal operating voltage to the power device under test (10) through the power frequency power supply (3), the step-up transformer (4) and the first circuit breaker (5), and to provide port impedance to the power device under test (10) through the load (9), the step-down transformer (8) and the three-phase power transmission cable (6); The first circuit breaker (5) is used to realize the connection and disconnection between the power frequency power supply (3) and the three-phase power transmission cable (6); The second circuit breaker (7) is used to switch the load (9) on and off with the three-phase power transmission cable (6); The capacitance value of the high-voltage coupling capacitor (2) is determined according to the environment of the strong electromagnetic pulse, and its withstand voltage value is determined according to the highest voltage output by the strong electromagnetic pulse source (1). One end of each of the three high-voltage coupling capacitors (2) is connected to one of the three phase lines of the three-phase power transmission cable (6), and the other end of each of the three high-voltage coupling capacitors (2) is connected together to form an equivalent "zero potential" point through the 120° phase difference of the three-phase power frequency voltage. The high voltage output terminal of the strong electromagnetic pulse source (1) is directly connected to the equivalent "zero potential" point. By triggering the strong electromagnetic pulse source (1), the strong electromagnetic pulse interference signal is loaded onto the port of the power equipment under test (10) under the power-on state.

2. The high electromagnetic pulse loading platform for power equipment under energized conditions according to claim 1, characterized in that: It also includes a voltage measurement probe, a first current sensor (11), a first voltage sensor (12), and an oscilloscope (13); The voltage measurement probe is used to measure the potential at the equivalent "zero potential" point; The first current sensor (11) is used to measure the current flowing through the output port of the strong electromagnetic pulse source (1), and the first voltage sensor (12) is used to measure the voltage at the output port of the strong electromagnetic pulse source (1). The output terminals of the voltage measurement probe, the first current sensor (11), and the first voltage sensor (12) are all used to connect to the input terminal of the oscilloscope (13).

3. A high-intensity electromagnetic pulse loading platform for power equipment under energized conditions, as described in claim 1 or 2, characterized in that: It also includes a second current sensor and a second voltage sensor; The second current sensor and the second voltage sensor are used to measure the current and voltage at a specified location of the electrical equipment under test (10), respectively. The output terminals of the second current sensor and the second voltage sensor are both used to connect to the input terminal of the oscilloscope (13).

4. A method for applying a strong electromagnetic pulse to power equipment under energized conditions, based on the strong electromagnetic pulse application platform for power equipment under energized conditions as described in any one of claims 1-3, characterized in that it includes the following steps: 1】Select a high-voltage coupling capacitor (2) The capacitance value is determined based on the environment of the strong electromagnetic pulse, and the withstand voltage value of the capacitor is determined based on the highest voltage output by the strong electromagnetic pulse source (1); based on the determined capacitance value and withstand voltage value, three capacitors with the same specifications that meet the requirements are selected as high-voltage coupling capacitors (2); 2. Construct an equivalent "zero potential" point 2.1】Build a three-phase transmission line test platform; the three-phase transmission line test platform includes a power frequency power supply (3), a step-up transformer (4), a first circuit breaker (5), a three-phase transmission cable (6), a second circuit breaker (7), a step-down transformer (8), and a load (9) connected in sequence; 2.2】The three-phase power transmission cable (6) is disconnected from the power frequency power supply (3) by the first circuit breaker (5), and one end of the three high-voltage coupling capacitors (2) is connected to each phase line of the three-phase power transmission cable (6) respectively. The other ends of the three high-voltage coupling capacitors (2) are connected together, so that the connection point of the three high-voltage coupling capacitors (2) forms an equivalent "zero potential" point. 3】Connect the output port of the strong electromagnetic pulse source (1) directly to the equivalent "zero potential" point; 4. Achieving the loading of strong electromagnetic pulses under powered conditions 4.1 Connect the power equipment to be tested (10) to the three-phase power transmission cable (6); 4.2】The three-phase power transmission cable (6) is connected to the power frequency power supply (3) by the first circuit breaker (5); 4.3】Turn on the power frequency power supply (3) to connect the three-phase power transmission cable (6) to the normal power frequency voltage; trigger the strong electromagnetic pulse source (1) to realize the loading of the strong electromagnetic pulse interference signal on the port of the power equipment under test (10) under the power-on state.

5. The method for applying a strong electromagnetic pulse to power equipment under energized conditions according to claim 4, characterized in that, Step 1】Specifically: 1.1】Measure the open-circuit voltage U of the strong electromagnetic pulse source (1) o and short-circuit current I s And according to the open circuit voltage U o and short-circuit current I s Calculate the internal resistance R of a strong electromagnetic pulse source (1) s ; 1.2】The frequency domain transformation of the output current of the strong electromagnetic pulse source (1) is performed to calculate the upper frequency limit f of the main energy concentration band of the strong electromagnetic pulse signal. H ; 1.3】Set the capacitor value C so that f H Equivalent impedance at frequency Negligible, i.e. 1.4】Set the capacitor's withstand voltage U according to the following formula. c-pulse : IN c-pulse =k*U m Among them, U m The maximum voltage output by the strong electromagnetic pulse source (1) is k, where k is the safety margin coefficient. k＝1.05～1.35； 1.5】Based on the capacitance value C obtained in step 1.3】 and the voltage rating U obtained in step 1.4】. c-pulse Three capacitors that meet the requirements and have the same specifications are selected as high-voltage coupling capacitors (2).

6. The method for applying a strong electromagnetic pulse to power equipment under energized conditions according to claim 5, characterized in that: In step 1.3, let The capacitance value In step 1.4, k = 1.

1.

7. A method for applying a strong electromagnetic pulse to power equipment under energized conditions according to any one of claims 4-6, characterized in that: Step 2 also includes Step 2.3: Measure the potential of the equivalent "zero potential" point using a voltage measurement probe to ensure the reliability of the equivalent "zero potential" point.

8. A method for applying a strong electromagnetic pulse to power equipment under energized conditions according to claim 7, characterized in that, Step 3】Specifically: The high voltage output terminal of the strong electromagnetic pulse source (1) is directly connected to the equivalent "zero potential" point, and the length of the connecting cable is kept to the minimum while ensuring the safe insulation distance between the pulse source and the three-phase power transmission cable (6).

9. A method for applying a strong electromagnetic pulse to power equipment under energized conditions according to claim 8, characterized in that: Step 3 also includes: connecting the three-phase power transmission cable (6) to the power frequency power supply (3) through the first circuit breaker (5), and then measuring the current and voltage flowing through the output port of the strong electromagnetic pulse source (1) through the first current sensor (11) and the first voltage sensor (12). If the current at the output port of the strong electromagnetic pulse source (1) is less than 0.5A, the voltage at the output port of the strong electromagnetic pulse source (1) is less than 25V, and the power frequency power supply (3) does not trip, it indicates that the high voltage output terminal of the strong electromagnetic pulse source (1) is correctly connected to the equivalent "zero potential" point.

10. A method for applying a strong electromagnetic pulse to power equipment under energized conditions according to claim 9, characterized in that, Step 4 is as follows: 4.1】The three-phase power transmission cable (6) is disconnected from the power frequency power supply (3) by the first circuit breaker (5), and the power equipment under test (10) is connected to the three-phase power transmission cable (6); a second voltage sensor and a second current sensor are set to measure the voltage and current at a specified location of the power equipment under test (10) respectively, and the signal lines of the current sensor and the voltage sensor are connected to the oscilloscope (13); 4.2】The three-phase power transmission cable (6) is connected to the power frequency power supply (3) by the first circuit breaker (5); 4.3】Turn on the power frequency power supply (3) and use the voltage signal on the oscilloscope (13) to determine whether the voltage applied to the power equipment under test (10) is the normal working voltage. When the voltage applied to the power equipment under test (10) is the normal working voltage, perform phase detection on the power frequency voltage to specify the triggering time of the strong electromagnetic pulse source (1) and perform superposition of the strong electromagnetic pulse interference signal on the specified phase of the power frequency voltage.

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