Series compensation device MOV explosion-proof performance test system and method

Abstract

A system and method for testing explosion-proof performance of a series compensation device MOV, the system includes: an industrial computer, a test device connected to the industrial computer in communication; the test device includes a short-circuit current branch, a discharge current branch, a test product branch and a DC charging power supply branch connected in parallel, the test product branch includes a MOV short-circuit test product; the short-circuit current branch includes an AC generator and a current limiting inductor, which are used to input the short-circuit current to the test product branch using the AC generator and the current limiting inductor; the discharge current branch includes a discharge capacitor and a wave modulation inductor, which are used to input the discharge current to the test product branch using the discharge capacitor and the wave modulation inductor; the DC charging power supply branch includes a DC charging power supply, which is used to charge the discharge capacitor; the industrial computer is used to control the operation of the DC charging power supply, obtain the current of the MOV short-circuit test product, and generate a current waveform diagram according to the current. The present invention achieves the most stringent assessment effect and realizes effective assessment of MOV explosion-proof performance.

Description

Technical Field

[0001] The present invention relates to, in particular to, a system and method for testing explosion-proof performance of a series compensation device MOV. Background Art

[0002] The series compensation device has the advantages of increasing the transmission capacity of the transmission line and enhancing the system stability. In recent years, it has been applied in many high-voltage and long-distance transmission lines in my country. The series capacitor bank is the core component of the series compensation device, and a metal oxide voltage limiter (MOV) is usually used as a protective device for the capacitor bank. When a fault occurs in the series-compensated line, the MOV needs to absorb the energy generated by the short-circuit current while limiting the overvoltage of the capacitor bank under the line fault. Therefore, the design energy of the MOV is very large, generally in the tens of MJ. Due to the large energy absorption, the MOV unit generally adopts a multi-column parallel structure, and the entire MOV group is composed of multiple MOV units in parallel. When the resistor column in a certain MOV unit is damp or the resistor is degraded, the shunt of the entire MOV group will be uneven during a short-circuit fault. The defective MOV unit will flow through more short-circuit current, causing the MOV to break down, which in turn causes the pressure release of the voltage limiter, and the series compensation device is forced to stop operating.

[0003] At present, except for a few MOVs in operation that use composite jackets, the rest of the MOVs in series compensation devices use porcelain jackets. The explosion-proof design performance assessment of MOV porcelain jackets adopts the requirements of short-circuit test in Section 8.10 of GB / T 11032-2020 "AC gapless metal oxide arresters". It stipulates that when the MOV is undergoing a short-circuit test (also known as a pressure release test), the internal part should be able to withstand a discharge current of about 110kA with a power frequency of 63kA / 0.2s at a peak frequency, without a porcelain jacket pulverizing explosion. However, the assessment conditions of this test only consider the influence of short-circuit current, and do not consider the influence of capacitor bank discharge current. Even if the MOV has passed the type test required by the national standard, its porcelain jacket may also pulverize and explode in the event of a MOV breakdown failure. Therefore, a new test method is needed to reliably assess the explosion-proof performance of MOV. Summary of the invention

[0004] In view of the problems existing in the prior art, the main purpose of the embodiments of the present invention is to provide a system and method for testing the explosion-proof performance of a series compensation device MOV, so as to effectively evaluate the explosion-proof performance of the MOV.

[0005] In order to achieve the above-mentioned object, an embodiment of the present invention provides a system for testing explosion-proof performance of a series compensation device MOV, the system comprising: an industrial computer, a testing device connected to the industrial computer for communication;

[0006] The test device comprises a short-circuit current branch, a discharge current branch, a test branch and a DC charging power supply branch, wherein the short-circuit current branch, the discharge current branch, the test branch and the DC charging power supply branch are connected in parallel, and the test branch comprises an MOV short-circuit test product;

[0007] The short-circuit current branch includes an AC generator and a current-limiting inductor, and the short-circuit current branch is used to obtain a preset short-circuit current by using the AC generator and the current-limiting inductor, and input the short-circuit current into the test branch; wherein the AC generator is connected in series with the current-limiting inductor;

[0008] The discharge current branch includes a discharge capacitor and a modulating inductor, and the discharge current branch is used to obtain a preset discharge current by using the discharge capacitor and the modulating inductor, and input the discharge current into the test branch; wherein the discharge capacitor is connected in series with the modulating inductor;

[0009] The DC charging power supply branch includes a DC charging power supply, and the DC charging power supply branch is used to charge the discharge capacitor;

[0010] The industrial computer is used to control the operation of the DC charging power supply, and obtain the current of the MOV short-circuit test product, and generate a current waveform diagram according to the current; wherein the current waveform diagram is used for MOV explosion-proof performance analysis.

[0011] Optionally, in one embodiment of the present invention, the short-circuit current branch further includes a first switch, and the first switch is connected in series with the AC generator and the current-limiting inductor.

[0012] Optionally, in an embodiment of the present invention, the discharge current branch further includes a second switch, and the second switch is connected in series with the discharge capacitor and the modulating inductor.

[0013] Optionally, in one embodiment of the present invention, the industrial computer is further used to control the second switch to close when the short-circuit current reaches a peak value.

[0014] Optionally, in an embodiment of the present invention, the DC charging power supply branch further includes a third switch and a fourth switch, the third switch is connected in series with the DC charging power supply, and the fourth switch is connected in parallel with the DC charging power supply.

[0015] Optionally, in an embodiment of the present invention, the discharge current branch further includes a voltage measuring device, and the voltage measuring device is connected in parallel with the discharge capacitor and is used to collect the voltage value of the discharge capacitor.

[0016] Optionally, in one embodiment of the present invention, the industrial computer is further used to receive a voltage value collected by the voltage measuring device, and when the voltage value reaches a preset full-power threshold, control the third switch to disconnect.

[0017] Optionally, in one embodiment of the present invention, the industrial computer is further used to control the first switch and the second switch to be disconnected, and control the fourth switch to be closed when the voltage value reaches a preset discharge threshold.

[0018] Optionally, in an embodiment of the present invention, the test branch further includes an ammeter, the ammeter is connected in series with the MOV short-circuit test product, and the ammeter is used to collect the current of the MOV short-circuit test product.

[0019] The embodiment of the present invention further provides a method for testing the explosion-proof performance of a series compensation device MOV, the method comprising:

[0020] Controlling a DC charging power supply in a DC charging power supply branch of the test device to charge a discharge capacitor in a discharge current branch until a voltage value of the discharge capacitor reaches a preset full-charge threshold;

[0021] Controlling the first switch to close so that the short-circuit current in the short-circuit current branch of the test device is input into the test product branch of the test device;

[0022] When the short-circuit current reaches a peak value, the second switch is controlled to close so that the discharge current in the discharge current branch is input into the test branch, and the current of the MOV short-circuit test product in the test branch is collected in real time through an ammeter;

[0023] When the voltage value of the discharge capacitor reaches a preset discharge threshold, the first switch and the second switch are controlled to be disconnected, and a current waveform diagram is generated according to the obtained current of the MOV short-circuit test product; wherein the current waveform diagram is used for MOV explosion-proof performance analysis.

[0024] Optionally, in an embodiment of the present invention, the method further includes: when the voltage value of the discharge capacitor reaches a preset discharge threshold, controlling a fourth switch connected in parallel with the DC charging power supply to close.

[0025] Optionally, in one embodiment of the present invention, the method further includes: controlling a third switch connected in series with the DC charging power supply to close so that the DC charging power supply charges the discharge capacitor, and controlling the third switch to open after the voltage value of the discharge capacitor reaches a preset full-charge threshold.

[0026] Optionally, in an embodiment of the present invention, the method further includes: acquiring a voltage value of the discharge capacitor by means of a voltage measuring device connected in parallel with the discharge capacitor.

[0027] The present invention generates industrial frequency current through an AC generator, combines a current limiting inductor to simulate a line short-circuit current, forms a high-frequency discharge loop through a discharge capacitor and a wave modulation inductor, realizes the simulation of the discharge current of the series compensation capacitor, and discharges the MOV test piece set to be short-circuited by connecting the short-circuit current branch and the discharge current branch in parallel, thereby achieving the most stringent assessment effect and realizing effective assessment of the explosion-proof performance of the MOV. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a structural schematic diagram of a system for testing the explosion-proof performance of a series compensation device MOV according to an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of current flowing through the MOV during a fault in an embodiment of the present invention;

[0031] Figure 3 The present invention is a flowchart of a method for testing the explosion-proof performance of a series compensation device MOV according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The embodiments of the present invention provide a system and method for testing the explosion-proof performance of a series compensation device MOV.

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] According to the electrical schematic diagram of the series compensation device in the system when a fault occurs, such as Figure 2 As shown, the series compensation capacitor and MOV are in parallel. When a short circuit occurs in the MOV, the current flowing through it will be the line current I L and capacitor discharge current I C The superposition of capacitor C1 discharge current I C It is a high-frequency current with high amplitude (hundreds of kA), high frequency (several kHz), and fast decay (several milliseconds). The pressure generated inside the MOV under this current is much greater than the line current I LTherefore, in order to effectively evaluate the explosion-proof performance of MOV, it is necessary to apply a capacitive discharge current to MOV, which is also lacking in the current short-circuit test.

[0035] like Figure 1 The figure shows a schematic diagram of the structure of a system for testing the explosion-proof performance of a series compensation device MOV according to an embodiment of the present invention. The system shown in the figure includes: an industrial computer and a testing device connected to the industrial computer for communication.

[0036] The test device includes a short-circuit current branch 1, a discharge current branch 3, a test branch 2 and a DC charging power supply branch 4. The short-circuit current branch 1, the discharge current branch 3, the test branch 2 and the DC charging power supply branch 4 are connected in parallel. The test branch 2 includes an MOV short-circuit test product, that is, Figure 1 The test products in .

[0037] The short-circuit current branch 1 includes an AC generator and a current-limiting inductor L1. The short-circuit current branch 1 is used to obtain a preset short-circuit current using the AC generator and the current-limiting inductor, and input the short-circuit current into the test branch 2; wherein the AC generator is connected in series with the current-limiting inductor L1.

[0038] The discharge current branch 3 includes a discharge capacitor C and a modulation inductor L2. The discharge current branch is used to utilize the discharge capacitor and the modulation inductor to obtain a preset discharge current and input the discharge current into the test branch 2; wherein the discharge capacitor and the modulation inductor are connected in series.

[0039] The DC charging power supply branch includes a DC charging power supply, and the DC charging power supply branch is used to charge the discharge capacitor.

[0040] The industrial computer is used to control the operation of the DC charging power supply, and obtain the current of the MOV short-circuit test product, and generate a current waveform diagram according to the current; wherein the current waveform diagram is used for MOV explosion-proof performance analysis.

[0041] In this embodiment, the test device includes a test MOV, an AC generator, a first switch S1, a current limiting inductor L1, an ammeter A, a second switch S2 with controllable closing time, a modulating inductor L2 with adjustable inductance, a discharge capacitor C with adjustable capacitance, a voltage measuring device V (such as a voltmeter), a third switch S3, a fourth switch S4, and a DC charging power supply. Figure 1 The solid line indicates electrical connection, the dotted line indicates signal transmission, and the arrow indicates the direction of signal transmission. The specific working process of the system includes: forming an AC current generating circuit through an AC generator and a current limiting inductor, injecting industrial frequency AC current into the MOV test piece to simulate the short-circuit current I flowing through the MOV when a ground fault occurs in the line L; The adjustable capacitor C is used to simulate the series compensation capacitor, and the oscillation frequency of the capacitor discharge current is changed by the modulation inductor L to simulate the discharge current I of the series compensation capacitor to the MOV during a fault. C The above two circuits are in parallel relationship, so that the power frequency current and the capacitor bank discharge current flow through the MOV at the same time to evaluate the explosion-proof performance of the MOV.

[0042] As an embodiment of the present invention, the short-circuit current branch further includes a first switch, which is connected in series with the AC generator and the current-limiting inductor.

[0043] In this embodiment, the discharge current branch further includes a second switch, and the second switch is connected in series with the discharge capacitor and the modulating inductor.

[0044] In this embodiment, the industrial computer is further configured to control the second switch to close when the short-circuit current reaches a peak value.

[0045] In this embodiment, the DC charging power supply branch further includes a third switch and a fourth switch, the third switch is connected in series with the DC charging power supply, and the fourth switch is connected in parallel with the DC charging power supply.

[0046] In this embodiment, the discharge current branch further includes a voltage measuring device, which is connected in parallel with the discharge capacitor and is used to collect the voltage value of the discharge capacitor.

[0047] In this embodiment, the industrial computer is further used to receive the voltage value collected by the voltage measuring device, and when the voltage value reaches a preset full-power threshold, control the third switch to be disconnected.

[0048] In this embodiment, the industrial computer is further configured to control the first switch and the second switch to be disconnected, and control the fourth switch to be closed, when the voltage value reaches a preset discharge threshold.

[0049] As an embodiment of the present invention, the test branch further includes an ammeter, which is connected in series with the MOV short-circuit test product and is used to collect the current of the MOV short-circuit test product.

[0050] Using the structure of the system of the present invention, the specific testing process of the system includes:

[0051] 1) According to the national standard GB / T 11032-2020, a fuse is placed inside the MOV to form a test product. At this time, the test product can be considered to be in a short-circuit state in the electrical circuit.

[0052] 2) According to the short-circuit current I of the line where the MOV to be tested is located L , adjust the current limiting inductor L1, L1 = U AC / IL .

[0053] Among them, U AC is the terminal voltage of the AC generator, the short-circuit current I L The value is determined by the actual short-circuit impedance of the power system at the line where the series compensation device is installed. Its maximum value is 80kA and can also be set according to actual needs.

[0054] 3) Adjust the capacitance of the discharge capacitor C according to the capacitance of the capacitor in series with the MOV, and adjust the modulation inductor L2 according to the required oscillation frequency f, L2 = 1 / f 2 C.

[0055] The capacitance value of the series compensation capacitor is one of the rated parameters of the series compensation device, which can be determined when designing the series compensation device. The capacitance range is about several hundred μF, and can also be set according to actual needs. The required oscillation frequency f is determined based on the experience of previous actual faults, which is about 3000Hz.

[0056] 4) According to the rated voltage of the series compensation device and its protection level, the charging voltage U of the DC charging power supply is set by the industrial computer. DC ; Close the S3 switch to charge the capacitor C. According to the voltage measured by the voltage measuring device V, open the S3 switch after charging is completed.

[0057] The industrial computer receives the voltage across the capacitor measured by the voltage measuring device and the set charging voltage U DC If the difference is within 1% and reaches stability, charging is considered complete.

[0058] 5) The industrial computer controls the closing of switch S1 to inject industrial frequency AC current into the test product.

[0059] 6) The closing time is controlled by an industrial computer. Specifically, the switch S2 can be controlled to close before or after the power frequency current reaches the peak value, so as to inject the high-frequency discharge current of the capacitor into the test product.

[0060] 7) After the test, open switches S1 and S2; close switch S4 and then close switch S3 to discharge capacitor C.

[0061] When the voltage across the capacitor C is close to 0 and remains stable, the test is considered to be completed.

[0062] 8) Turn off the AC generator, check the status of the test product, and retain the current waveform flowing through the MOV in this test. The current is measured by ammeter A and transmitted to the industrial computer for storage.

[0063] The test product status refers to the integrity of the MOV jacket. The test product status can determine whether the explosion-proof performance of the test product meets the application requirements. If it is intact or collapsed, it is considered qualified, and if it splashes or catches fire, it is considered unqualified.

[0064] Furthermore, the current waveform can be subsequently used for simulating and calculating the gas pressure inside the jacket, determining the pressure distribution, improving the jacket structure, and the like.

[0065] The present invention generates an industrial frequency current through an AC generator to simulate a line short-circuit current, and forms a high-frequency discharge circuit through an adjustable capacitor and an adjustable inductor to simulate the discharge current of a series compensation capacitor. The above two circuits are in a parallel relationship, and a switch with controllable closing time is used to ensure that the capacitor discharge current is superimposed on the peak value of the industrial frequency current, thereby achieving the most stringent assessment effect.

[0066] The present invention generates power frequency current through an AC generator, combines a current limiting inductor to simulate a line short-circuit current, forms a high-frequency discharge loop through a discharge capacitor and a wave modulation inductor, realizes the simulation of the discharge current of the series compensation capacitor, and ensures that the capacitor discharge current is superimposed on the power frequency current peak value through a switch with controllable closing time, thereby achieving the most stringent assessment effect and realizing effective assessment of MOV explosion-proof performance.

[0067] like Figure 3 The flowchart of a method for testing the explosion-proof performance of a series compensation device MOV according to an embodiment of the present invention is shown. The execution subject of the method for testing the explosion-proof performance of a series compensation device MOV according to an embodiment of the present invention includes but is not limited to an industrial computer. The method shown in the figure includes:

[0068] Step S1, controlling a DC charging power supply in a DC charging power supply branch of a test device to charge a discharge capacitor in a discharge current branch until a voltage value of the discharge capacitor reaches a preset full charge threshold;

[0069] Step S2, controlling the first switch to close so that the short-circuit current in the short-circuit current branch of the testing device is input into the test product branch of the testing device;

[0070] Step S3, when the short-circuit current reaches a peak value, the second switch is controlled to be closed, so that the discharge current in the discharge current branch is input into the test branch, and the current of the MOV short-circuit test product in the test branch is collected in real time through an ammeter;

[0071] Step S4, when the voltage value of the discharge capacitor reaches a preset discharge threshold, the first switch and the second switch are controlled to be disconnected, and a current waveform diagram is generated according to the obtained current of the MOV short-circuit test sample; wherein the current waveform diagram is used for MOV explosion-proof performance analysis.

[0072] As an embodiment of the present invention, the method further includes: when the voltage value of the discharge capacitor reaches a preset discharge threshold, controlling a fourth switch connected in parallel with the DC charging power supply to close.

[0073] As an embodiment of the present invention, the method further includes: controlling a third switch connected in series with the DC charging power supply to close so that the DC charging power supply charges the discharge capacitor, and controlling the third switch to open after the voltage value of the discharge capacitor reaches a preset full-charge threshold.

[0074] As an embodiment of the present invention, the method further includes: obtaining a voltage value of the discharge capacitor by means of a voltage measuring device connected in parallel with the discharge capacitor.

[0075] Based on the same application concept as the above-mentioned series compensation device MOV explosion-proof performance test system, the present invention also provides the above-mentioned series compensation device MOV explosion-proof performance test method. Since the principle of solving the problem by the series compensation device MOV explosion-proof performance test method is similar to that of the series compensation device MOV explosion-proof performance test system, the implementation of the series compensation device MOV explosion-proof performance test method can refer to the implementation of the series compensation device MOV explosion-proof performance test system, and the repeated parts will not be repeated.

[0076] The present invention generates power frequency current through an AC generator, combines a current limiting inductor to simulate a line short-circuit current, forms a high-frequency discharge loop through a discharge capacitor and a wave modulation inductor, realizes the simulation of the discharge current of the series compensation capacitor, and ensures that the capacitor discharge current is superimposed on the power frequency current peak value through a switch with controllable closing time, thereby achieving the most stringent assessment effect and realizing effective assessment of MOV explosion-proof performance.

[0077] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A series compensation device MOV explosion-proof performance test system, characterized in that: The system comprises: an industrial computer, and a testing device connected to the industrial computer for communication; The test device comprises a short-circuit current branch, a discharge current branch, a test branch and a DC charging power supply branch, wherein the short-circuit current branch, the discharge current branch, the test branch and the DC charging power supply branch are connected in parallel, and the test branch comprises an MOV short-circuit test product; The short-circuit current branch includes an AC generator and a current-limiting inductor, and the short-circuit current branch is used to obtain a preset short-circuit current by using the AC generator and the current-limiting inductor, and input the short-circuit current into the test branch; wherein the AC generator is connected in series with the current-limiting inductor; The discharge current branch includes a discharge capacitor and a modulating inductor, and the discharge current branch is used to obtain a preset discharge current by using the discharge capacitor and the modulating inductor, and input the discharge current into the test branch; wherein the discharge capacitor is connected in series with the modulating inductor; The DC charging power supply branch includes a DC charging power supply, and the DC charging power supply branch is used to charge the discharge capacitor; The industrial computer is used to control the operation of the DC charging power supply, and obtain the current of the MOV short-circuit test product, and generate a current waveform diagram according to the current; wherein the current waveform diagram is used for MOV explosion-proof performance analysis.

2. The system according to claim 1, characterized in that The short-circuit current branch also includes a first switch, which is connected in series with the AC generator and a current-limiting inductor.

3. The system according to claim 2, characterized in that The discharge current branch further includes a second switch, which is connected in series with the discharge capacitor and the modulating inductor.

4. The system according to claim 3, characterized in that The industrial computer is further configured to control the second switch to close when the short-circuit current reaches a peak value.

5. The system according to claim 3, characterized in that The DC charging power supply branch further includes a third switch and a fourth switch, the third switch is connected in series with the DC charging power supply, and the fourth switch is connected in parallel with the DC charging power supply.

6. The system according to claim 5, characterized in that The discharge current branch further includes a voltage measuring device, which is connected in parallel with the discharge capacitor and is used to collect a voltage value of the discharge capacitor.

7. The system according to claim 6, characterized in that The industrial computer is also used to receive the voltage value collected by the voltage measuring device, and when the voltage value reaches a preset full-power threshold, control the third switch to be disconnected.

8. The system according to claim 7, characterized in that The industrial computer is further configured to control the first switch and the second switch to be disconnected, and control the fourth switch to be closed, when the voltage value reaches a preset discharge threshold.

9. The system according to claim 1, characterized in that The test branch also includes an ammeter, which is connected in series with the MOV short-circuit test product and is used to collect the current of the MOV short-circuit test product.

10. A method for testing the explosion-proof performance of a series compensation device MOV, characterized in that: The method comprises: Controlling a DC charging power supply in a DC charging power supply branch of the test device to charge a discharge capacitor in a discharge current branch until a voltage value of the discharge capacitor reaches a preset full-charge threshold; Controlling the first switch to close so that the short-circuit current in the short-circuit current branch of the test device is input into the test product branch of the test device; When the short-circuit current reaches a peak value, the second switch is controlled to close so that the discharge current in the discharge current branch is input into the test branch, and the current of the MOV short-circuit test product in the test branch is collected in real time through an ammeter; When the voltage value of the discharge capacitor reaches a preset discharge threshold, the first switch and the second switch are controlled to be disconnected, and a current waveform diagram is generated according to the obtained current of the MOV short-circuit test product; wherein the current waveform diagram is used for MOV explosion-proof performance analysis.

11. The method according to claim 10, characterized in that The method further includes: when the voltage value of the discharge capacitor reaches a preset discharge threshold, controlling a fourth switch connected in parallel with the DC charging power supply to close.

12. The method according to claim 10, characterized in that The method further includes: controlling a third switch connected in series with the DC charging power supply to close so that the DC charging power supply charges the discharge capacitor, and controlling the third switch to open after the voltage value of the discharge capacitor reaches a preset full-charge threshold.

13. The method according to claim 10, characterized in that The method further includes: obtaining a voltage value of the discharge capacitor by means of a voltage measuring device connected in parallel with the discharge capacitor.

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