Simulated ablation test platform and test method for filter bank circuit breaker

Abstract

The invention provides a simulation ablation test platform and test method for a filter bank circuit breaker, and relates to the technical field of circuit breaker contacts, and the test platform comprises a simulation breaking ablation module which is connected in series with a to-be-tested test circuit breaker, and simulates the opening operation to carry out the accelerated ablation of the contact of the test circuit breaker; the switching erosion simulation module is used for being connected in series with a to-be-tested test circuit breaker and simulating switching-on operation to perform accelerated ablation on a contact of the test circuit breaker; and the dynamic contact resistance test module is used for being connected to two ends of the test circuit breaker to be tested and monitoring the voltage of the contact, the current flowing through the contact and the stroke signal in the opening or closing process of the test circuit breaker so as to determine the dynamic change of the contact resistance of the contact. According to the scheme, accelerated ablation can be carried out on the circuit breaker by simulating the opening and closing working conditions of the circuit breaker, and then the service life state of the circuit breaker is tested and evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of circuit breaker contacts, and in particular to a simulated ablation test platform and a test method for a filter group circuit breaker. Background Art

[0002] The converter station is equipped with a large-capacity AC filter group to supplement the large amount of reactive power consumed by nonlinear components such as converter valves and filter out the harmonic components that cause system voltage and current distortion. The SF6 circuit breaker used in the filter group needs to be switched on and off at any time according to the changes in the system operating conditions and the demand for reactive power and filtering to complete the input and removal of the filter group.

[0003] The filter group circuit breaker in the converter station operates more frequently than other circuit breakers. During the closing process, high-amplitude and high-frequency surge currents will be generated. The contacts and nozzles of the arc extinguishing chamber will seriously reduce their breaking performance due to the accumulated closing arc erosion and mechanical wear. During the breaking process, the breaking current is a multi-dimensional capacitive small current, the arc is not fully burning, the arc channel is a non-equilibrium plasma, and the recovery voltage is high and has a DC component during the breaking process, which is prone to the risk of reignition, breaking failure and even explosion, seriously affecting the safe operation of the power grid. There have been many safety accidents in the power system caused by the decline of the arc extinguishing ability of the circuit breaker, and the number of breaking times is far lower than the prescribed number.

[0004] At present, when inspecting and repairing the filter group circuit breaker, the filter group circuit breaker is usually disassembled for testing and repair after reaching the set number of interruptions or operating years, which makes it difficult to conduct timely and accurate evaluation of the electrical life and status of the circuit breaker. Summary of the invention

[0005] In view of this, in order to address the above shortcomings, it is necessary to propose a simulated ablation test platform and test method for filter group circuit breaker, which can accelerate the ablation of the circuit breaker by simulating the opening and closing conditions of the circuit breaker, and then test and evaluate the life status of the circuit breaker.

[0006] In a first aspect, the present invention provides a simulated ablation test platform for a filter bank circuit breaker, comprising: a simulated opening ablation module, a simulated closing erosion module and a dynamic contact resistance test module;

[0007] The simulated breaking and ablation module is used to connect in series the test circuit breaker to be tested, and simulate the opening operation to accelerate the ablation of the test circuit breaker contacts;

[0008] The simulated closing erosion module is used to connect in series to the test circuit breaker to be tested, and simulate the closing operation to accelerate the ablation of the test circuit breaker contacts;

[0009] The dynamic contact resistance test module is used to be connected to both ends of the test circuit breaker to be tested, and monitor the voltage of the contacts, the current flowing through the contacts and the travel signal during the opening or closing process of the test circuit breaker to determine the dynamic change of the contact resistance.

[0010] Preferably, the circuit for simulating the breaking and ablation module comprises:

[0011] One end of the switches K1 and K2 are both connected to the three-phase alternating current, and the other ends are both connected to the thyristor unit. One end of the resistor R1 is connected to the thyristor unit, and the other end is connected to the first end of the primary coil of the transformer. One end of the resistor R2 is respectively connected to the thyristor unit and the second end of the primary coil of the transformer, and the other end of the resistor R2 is connected to the first end of the primary coil of the transformer. One end of the resistor R3 is connected to the first end of the secondary coil of the transformer, and the other end is connected to the positive electrode of the diode D1. The negative electrode of the diode is connected to one end of the inductor L1. The other end of the inductor L1 is connected to one end of the protection circuit breaker QF1. The other end of the protection circuit breaker QF1 is connected to one end of the closing circuit breaker QF2. The other end of the closing circuit breaker QF2 is used to be connected to the first end of the test circuit breaker QF to be tested. One end of the capacitor group C1 is connected to the negative electrode of the diode D1, and the other end is connected to the second end of the secondary coil of the transformer. The second end of the secondary coil of the transformer is also used to be connected to the second end of the test circuit breaker QF to be tested.

[0012] Preferably, the simulated breaking and ablation module further comprises: a timing control unit, which is used to control the actions of each circuit breaker in the simulated breaking and ablation module according to a preset sequence.

[0013] Preferably, the circuit for simulating the closing erosion module includes:

[0014] A first end of the power supply AC is connected to the anode of the diode D2, one end of the switch K3 is connected to the cathode of the diode D2, and the other end is connected to one end of the resistor R4, the other end of the resistor R4 is connected to one end of the inductor L2, the other end of the inductor L2 is connected to one end of the switch K4, the other end of the switch K4 is used to be connected to the first end of the test circuit breaker QF to be tested, one end of the capacitor C2 is connected to the line between the switch K3 and the resistor R4, and the other end is connected to the second end of the power supply AC, and the second end of the power supply AC is also used to be connected to the second end of the test circuit breaker QF to be tested.

[0015] Preferably, the circuit of the dynamic contact resistance test module includes:

[0016] The positive electrode of the charging power supply DC is connected to one end of the charging switch K, the other end of the charging switch K is connected to one end of the resistor R, the other end of the resistor R is connected to one end of the Hall coil H, and the other end of the Hall coil H is used to be connected to the first end of the test circuit breaker to be tested; one end of the capacitor Rc is connected to the line between the resistor R and the Hall coil H, and the other end is connected to one end of the capacitor Cc and is respectively connected to the negative electrode of the charging power supply DC and the ground terminal, and the negative electrode of the charging power supply DC is also used to be connected to the second end of the test circuit breaker to be tested.

[0017] Preferably, the test circuit breaker to be tested is a SF6 high-voltage circuit breaker with a rated closing short-circuit current of 63kA; the opening action time of the test circuit breaker is 32.5ms-33ms, and the closing action time of the closing circuit breaker is 42.8ms-43ms.

[0018] In a second aspect, the present invention provides a simulated ablation test method for a filter bank circuit breaker. The test method is implemented based on the simulated ablation test platform for the filter bank circuit breaker as described in the first aspect. The method comprises:

[0019] Determine the allowable breaking ablation times and the allowable closing erosion times that can make the circuit breaker electrical life reach the life limit;

[0020] Using the simulated breaking and ablation module of the simulated ablation test platform of the filter group circuit breaker, within the range of the allowable breaking and ablation times, simulate the opening operation to accelerate the ablation of the test circuit breaker contacts;

[0021] Or, using the simulated closing erosion module of the simulated ablation test platform of the filter bank circuit breaker, simulate the closing operation within the range of the allowable closing erosion times to accelerate the erosion of the test circuit breaker contacts;

[0022] The dynamic contact resistance test module of the filter bank circuit breaker simulation ablation test platform is used to monitor the contact voltage, current flowing through the contact and travel signal during the opening or closing process of the test circuit breaker to determine the dynamic change of the contact resistance.

[0023] Preferably, the determining of the allowable number of interruption ablation times that can make the electrical life of the circuit breaker reach the life limit includes:

[0024] Use the following calculation formula to determine the allowable breaking and burning times of the circuit breaker:

[0025]

[0026] Among them, N s Used to characterize the allowable breaking and burning times of the circuit breaker, I s Used to characterize breaking current.

[0027] Preferably, the determining of the allowable closing corrosion times that can make the electrical life of the circuit breaker reach the life limit includes:

[0028] According to the report of C2 test of circuit breaker, determine the ablation energy in C2 test of test circuit breaker;

[0029] The arc burning time is tested every M times, and the current during the arc burning time after the current surge is integrated to obtain the charge transferred each time by the arc;

[0030] When the accumulated arc transfer charge of ablation is equal to the energy of ablation during the C2 level test, the allowable number of closing erosions is confirmed.

[0031] Preferably, when the simulated breaking and ablation module is used to accelerate the ablation of the test circuit breaker contacts, a timing control unit is used to control the sequence of each circuit breaker;

[0032] During one ablation process, the working states of each circuit breaker in the simulated opening and closing ablation module include: first, the protective circuit breaker and the test circuit breaker are in the closed state, the closing circuit breaker is in the open state, the transformer charges the capacitor, and when the voltage reaches a predetermined value, the charging stops; then, the closing circuit breaker is actuated, the circuit is connected, the states of the test circuit breaker and the protective circuit breaker remain unchanged, and a power frequency attenuation current appears in the circuit; finally, after a set delay, the test circuit breaker is opened, the closing circuit breaker and the protective circuit breaker are in the closed state, an arc is generated in the arc extinguishing chamber of the test circuit breaker, and the arc is extinguished after the current passes through the zero point.

[0033] It can be seen from the above technical scheme that the simulated ablation test platform and test method of the filter group circuit breaker provided by this scheme include a simulated opening and closing ablation module, a simulated closing erosion module and a dynamic contact resistance test module. By connecting the test circuit breaker to be tested to the simulated opening and closing ablation module, the opening operation can be simulated to accelerate the ablation of the test circuit breaker contacts. Similarly, by connecting the test circuit breaker to be tested to the simulated closing erosion module, the closing operation can be simulated to accelerate the ablation of the test circuit breaker contacts. Furthermore, by connecting the dynamic contact resistance test module to both ends of the test circuit breaker to be tested, the voltage of the contacts, the current flowing through the contacts and the travel signal during the opening and closing process of the test circuit breaker can be monitored, thereby determining the dynamic change of the contact resistance of the contacts. It can be seen that this test platform can simulate the ablation of contacts after various opening and closing operations of the circuit breaker, and then evaluate the contact life of the circuit breaker after a certain number of opening and closing operations through the dynamic contact resistance test. In this way, there is no need to wait until the number of opening and closing times or the operating years reach a certain number before performing maintenance to determine the contact condition of the circuit breaker, and the life evaluation of the circuit breaker after various actual operating conditions can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a simulated ablation test platform for a filter bank circuit breaker provided in an embodiment of the present invention.

[0035] Figure 2 A circuit diagram of a simulated breaking and ablation module provided in an embodiment of the present invention.

[0036] Figure 3 A circuit diagram of a closing erosion simulation module provided by an embodiment of the present invention.

[0037] Figure 4 A circuit diagram of a dynamic contact resistance test module provided in an embodiment of the present invention.

[0038] Figure 5 Directly test the current and voltage of the circuit breaker during the breaking process.

[0039] Figure 6 This is the inrush current waveform during the circuit breaker closing process.

[0040] Figure 7 It is the equivalent circuit of the current source loop.

[0041] Figure 8 This is the attenuation waveform of the power frequency current when the circuit is unloaded.

[0042] Fig. 9 This is the timing diagram of the circuit breaker action in the simulated ablation test.

[0043] Fig.10 It is the current, voltage and stroke waveform of the circuit breaker closing and opening action.

[0044] Fig.11 It is the curve of dynamic resistance and stroke changing with time during the closing and opening process.

[0045] Fig.12 It is the dynamic resistance-stroke curve of closing and opening process.

[0046] Fig.13 Schematic diagram for calculating characteristic parameters of dynamic resistance curve.

[0047] Fig.14 Dynamic resistance curves under different test currents. DETAILED DESCRIPTION

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0049] The zero crossing of the AC current creates favorable conditions for arc extinction. As long as the arc gap channel does not reignite after the current passes through zero, the arc will eventually go out. Starting from the time when the arc current passes through zero, two opposite processes will occur in the arc gap, namely: the voltage recovery process and the dielectric strength recovery process. At the moment when the current passes through zero and the arc is extinguished, the voltage on the arc gap is the arc extinction voltage Ux. After the circuit is disconnected at the current zero crossing, the voltage of the arc gap should change from Ux to the power supply voltage at this time. Due to the presence of capacitance and inductance in the actual circuit, the voltage cannot jump directly, so the voltage on the arc gap will undergo a transition process, which is called the voltage recovery process. In this process, the voltage appearing at both ends of the arc gap is called the transient recovery voltage. The voltage recovery process is related to the circuit parameters and the arc gap performance. It can be periodic or non-periodic, such as Figure 5 shown.

[0050] After the current passes through the zero point and the arc is extinguished, the process in which the arc gap gradually changes from the original conductive channel to an insulating medium is called the dielectric strength recovery process. The dielectric strength of the arc gap is characterized by the voltage that it can withstand. The recovery of the dielectric strength of the arc gap after the contact breaks the current is called the hot dielectric strength recovery characteristic. Since there is still residual plasma in the arc gap for a short time after the arc is extinguished, it will seriously affect the recovery of the dielectric strength, so that the dielectric recovery characteristics after the arc is extinguished are significantly different from the no-load dielectric recovery characteristics. The voltage recovery process increases the arc gap voltage, which may cause the arc gap to break down again. The dielectric strength recovery process increases the dielectric strength of the arc gap, which will hinder the arc gap from breaking down again and eventually extinguish the arc. Therefore, whether the arc is extinguished or not depends on the "competition" of these two processes that occur simultaneously but have opposite effects.

[0051] In actual operation, the large current (fault current) and high voltage (recovery voltage) that the circuit breaker bears during the entire opening process need to be provided by the same independent power supply, which places high demands on the power supply capacity. It is uneconomical and sometimes even impossible to use direct tests for assessment. Figure 5 As can be seen from the current and voltage waveforms during the circuit breaker opening process, it can be found that the transient recovery voltage acting on both ends of the circuit breaker break and the fault current flowing through the circuit breaker do not appear at the same time. Therefore, the entire circuit breaker opening process can be divided into three independent stages:

[0052] (1) High current stage: the period from contact separation to the time before the arc voltage changes significantly before the current crosses the zero point. During this process, a large fault current flows through the circuit breaker, the break maintains a low resistance, and the voltage acting on both ends of the break is approximately the arc voltage.

[0053] (2) Interaction stage: that is, a short period of time before the current passes through zero and the arc is extinguished. When the short-circuit current load is transferred to the high voltage load, as the current tends to zero, the arc voltage may rise, charging the parallel capacitor and distorting the arc current. After the current zero point, the post-arc conductivity will produce additional damping on the transient recovery voltage, thereby affecting the voltage at both ends of the circuit breaker and the energy of the input contact gap;

[0054] (3) High voltage stage: that is, the stage when the gap is under the action of recovery voltage after the current passes through zero point and extinguishes. In this process, the gap has been transformed into a high-resistance state, and the current flowing through the gap is a post-arc current with a very small amplitude, but the voltage acting on both ends of the fracture is a rapidly rising transient recovery voltage and a continuous steady-state recovery voltage.

[0055] Since the high current and high voltage do not act on the circuit breaker at the same time during the actual breaking process, two power sources can be used to provide the current flowing through the circuit breaker under test and the recovery voltage acting on both ends of the circuit breaker during the test, which are called the current source circuit and the voltage source circuit respectively. However, since the post-arc current after the arc is extinguished in the high voltage stage is very small, it has little effect on the contact erosion. Therefore, the erosion of the circuit breaker is mainly in the high current stage before the current passes through zero, and whether the current is successfully broken or not has nothing to do with the voltage source. Therefore, in the contact simulation ablation test, the voltage source circuit can be omitted, and only the current source circuit can be used to achieve the same contact ablation effect as the actual breaking of the short-circuit current.

[0056] See the schematic diagram of the inrush current waveform during the closing process of the filter bank circuit breaker. Figure 6 As can be seen from the figure, the entire closing process of the circuit breaker can be divided into the following three stages:

[0057] (1) The circuit breaker receives a closing signal and the contacts start to move. Although both ends of the circuit breaker are subject to voltage, the distance between the contacts is large and no pre-breakdown occurs. The entire circuit remains disconnected and there is no current in the circuit.

[0058] (2) Pre-breakdown stage: This is the period from the occurrence of the pre-breakdown arc to the time before the contacts make contact. During this process, the circuit is turned on due to the pre-breakdown, and a high-frequency attenuated closing surge current flows through the circuit breaker. The arc resistance is between the breaks, and the voltage acting on both ends of the breaks is the system voltage.

[0059] (3) Contact contact stage: the time from the contact to the circuit breaker closing. During this process, the arc between the broken ends disappears due to the contact, and the current is formed by the contact resistance. At this time, the inrush current stage has not yet ended. After the inrush current stage ends, the current in the circuit becomes the system operating current.

[0060] From the above analysis, it can be seen that when the AC filter is put into use, a high-frequency attenuation closing inrush current with a large amplitude will be caused. This current will erode the arc contact due to the occurrence of pre-breakdown before the circuit breaker contacts are in contact, causing the contacts to soften due to temperature rise. When the contacts are in contact with each other, the contact erosion caused by mechanical wear accounts for a large proportion. The closing inrush current is generated by components such as capacitors in the system and will not disappear after the contacts are in contact. Therefore, during the test, the capacitance and inductance parameters in the test circuit should be reasonably configured to simulate the closing inrush current generated in actual operation, so as to achieve the erosion and softening of the contacts by the arc generated during the pre-breakdown process in the simulated closing experiment, which is more consistent with the actual operation.

[0061] Based on this, Figure 1 As shown, the present invention provides a simulated ablation test platform for a filter bank circuit breaker, comprising: a simulated breaking ablation module 10, a simulated closing erosion module 20 and a dynamic contact resistance test module 30;

[0062] The simulated breaking and ablation module 10 is used to connect in series the test circuit breaker to be tested, and simulate the opening operation to accelerate the ablation of the test circuit breaker contacts;

[0063] The simulated closing erosion module 20 is used to connect in series the test circuit breaker to be tested and simulate the closing operation to accelerate the ablation of the test circuit breaker contacts;

[0064] The dynamic contact resistance test module 30 is used to be connected to both ends of the test circuit breaker to be tested, and monitor the voltage of the contacts, the current flowing through the contacts and the travel signal during the opening or closing process of the test circuit breaker to determine the dynamic change of the contact resistance.

[0065] For the simulation of breaking the ablation module 10, the equivalent schematic diagram of the current source loop discharge is as follows Figure 7 As shown, Ci is the equivalent capacitor, Li is the loop inductance, and R is the equivalent resistance of the loop. After the capacitor Ci is charged through the capacitor control system, the resistor R and inductor Li in the circuit are discharged to form a discharge loop. If the influence of the arc voltage is not considered, this circuit is a passive second-order RLC circuit. Through analysis, the following formula can be obtained. The generated current waveform is a decaying oscillation waveform, and the peak value of the first peak is proportional to the charging voltage. Therefore, the size of the ablation current I m Just change the charging voltage:

[0066]

[0067] The charging voltage control part is mainly used to provide the specified charging voltage U0. When working, after closing the low-voltage main contactor switches K1 and K2, the primary voltage of the 380V / 200KV charging transformer is controlled by the thyristor module, and the secondary AC high voltage of the charging transformer is controlled accordingly, and the main capacitor group is charged to the voltage setting value through half-wave rectification. The current generating part is mainly used to provide the current required during the circuit breaker breaking process, and the maximum single-phase output current is 63kA.

[0068] Therefore, if Figure 2 As shown, the circuit for simulating the breaking and ablation module 10 may include:

[0069] One end of the switches K1 and K2 are both connected to the three-phase alternating current, and the other ends are both connected to the thyristor unit. One end of the resistor R1 is connected to the thyristor unit, and the other end is connected to the first end of the primary coil of the transformer. One end of the resistor R2 is respectively connected to the thyristor unit and the second end of the primary coil of the transformer, and the other end of the resistor R2 is connected to the first end of the primary coil of the transformer. One end of the resistor R3 is connected to the first end of the secondary coil of the transformer, and the other end is connected to the positive electrode of the diode D1. The negative electrode of the diode is connected to one end of the inductor L1. The other end of the inductor L1 is connected to one end of the protection circuit breaker QF1. The other end of the protection circuit breaker QF1 is connected to one end of the closing circuit breaker QF2. The other end of the closing circuit breaker QF2 is used to be connected to the first end of the test circuit breaker QF to be tested. One end of the capacitor group C1 is connected to the negative electrode of the diode D1, and the other end is connected to the second end of the secondary coil of the transformer. The second end of the secondary coil of the transformer is also used to be connected to the second end of the test circuit breaker QF to be tested.

[0070] In this embodiment, the simulated breaking and ablation module 10 can mainly include a breaking and ablation test circuit and an arc ablation test circuit, which are mainly composed of capacitors, reactors, resistors, test transformers, rectifier silicon stacks and test circuit breaker models, and the test current is provided by an oscillation circuit composed of capacitors and reactors.

[0071] Specifically, the charging voltage control part in the opening and closing ablation simulation module 10 is mainly used to provide the specified charging voltage. During operation, after closing the low-voltage main contactor switches K1 and K2, the primary voltage of the 380V / 200kV charging transformer is controlled by the thyristor unit, and the secondary AC high voltage of the charging transformer is correspondingly controlled, and the main capacitor group is charged to the voltage setting value through half-wave rectification. The current generating part is mainly used to provide the current required during the circuit breaker opening process, and the maximum single-phase output current is 63kA. The protection circuit breaker mainly plays a protective role. When the test circuit breaker fails to open, the protection circuit breaker performs the opening action to protect the circuit and the safety of the experimenter. The test circuit breaker is a research object and is used to study the contact state in the simulated ablation test. The closing circuit breaker plays the role of keeping the circuit flowing, ensuring that the test circuit breaker can normally break the current, and is in the opening state before the test starts.

[0072] In addition, each circuit breaker can be opened and closed by manual operation. In one embodiment, in order to ensure that the test SF6 circuit breaker can break the arc current in each ablation, the simulated opening and closing ablation module 10 can also include a timing control unit for controlling the actions of each circuit breaker in the simulated opening and closing ablation module 10 according to a preset sequence. For example, in a single ablation process, the working state of each circuit breaker in the simulated opening and closing ablation module 10 includes: first, the protective circuit breaker and the test circuit breaker are in the closed state, the closing circuit breaker is in the open state, the transformer charges the capacitor, and when the voltage reaches a predetermined value, the charging stops; then, the closing circuit breaker is actuated, the circuit is turned on, the states of the test circuit breaker and the protective circuit breaker remain unchanged, and the power frequency attenuation current appears in the circuit; finally, after a set delay, the test circuit breaker opens, the closing circuit breaker and the protective circuit breaker are in the closed state, an arc is generated in the arc extinguishing chamber of the test circuit breaker, and the arc is extinguished after the current passes through zero, and a single ablation test ends.

[0073] In the simulation breaking and ablation module 10, the current source part is an oscillation circuit composed of capacitors and inductors connected in series, wherein the capacitor group C1 is composed of 240 5kV / 280μF capacitors, each 60 capacitors are connected in series to form a group of capacitors, the capacitance value is 16.8mF, and 4 groups of capacitors are connected in parallel. The series inductance is 0.603mH, and the rated voltage and rated current are 63kA / 10kV.

[0074] In this embodiment, the closing circuit breaker QF2 can adopt ZN-63 type vacuum circuit breaker with a rated closing current of 50kA and a mechanical operating mechanism. The test circuit breaker can adopt SF6 high-voltage circuit breaker with the main contacts removed and only the arc contacts retained, with a rated closing short-circuit current of 63kA. The structure can be a tank type circuit breaker with single or double ports to meet various cutting phenomena.

[0075] The no-load current waveform generated after the ablation circuit is turned on is shown in Figure 8 . It can be seen that due to the existence of loop resistance, the current waveform amplitude generated by the LC resonant circuit is attenuated by more than 30% in the third waveform. Therefore, in order to ensure that the current produces a better ablation effect, the circuit breaker needs to be disconnected before the second peak. Since there is a certain degree of dispersion when the operating mechanism of the circuit breaker is in action, a high-precision action signal control system is required, which can output several level pulse signals and optical pulse signals. The time delay between several signals can be set through the screen control button, with an accuracy of up to microseconds, meeting the control requirements for millisecond-level signals of the circuit breaker action response time.

[0076] Furthermore, after multiple tests, the opening action time of the test circuit breaker is 32.5-33ms, and the closing action time of the closing circuit breaker is 42.8-43ms. The action timing diagram of the circuit breaker during the ablation test is as follows: Fig. 9 shown.

[0077] For the simulation closing erosion module 20, as Figure 3 As shown, the circuit may include:

[0078] A first end of the power supply AC is connected to the anode of the diode D2, one end of the switch K3 is connected to the cathode of the diode D2, and the other end is connected to one end of the resistor R4, the other end of the resistor R4 is connected to one end of the inductor L2, the other end of the inductor L2 is connected to one end of the switch K4, the other end of the switch K4 is used to be connected to the first end of the test circuit breaker QF to be tested, one end of the capacitor C2 is connected to the line between the switch K3 and the resistor R4, and the other end is connected to the second end of the power supply AC, and the second end of the power supply AC is also used to be connected to the second end of the test circuit breaker QF to be tested.

[0079] In this embodiment, the closing erosion simulation module 20 mainly includes a closing ablation test circuit and an arc ablation test circuit, wherein the closing ablation test circuit is mainly composed of capacitors, reactors, resistors, test transformers, rectifier silicon stacks, test circuit breaker models, etc., and the test current is provided by an oscillation circuit composed of capacitors and reactors.

[0080] Specifically, in the simulation closing erosion module 20, R4 is a resistor, L2 is a reactor, C2 is a capacitor, K3 is a control switch for controlling the charging of the capacitor, and K4 is a control switch for controlling the test circuit. When ablation is performed, a current of more than 20kA is used. The measurement of dynamic contact resistance can be monitored in real time, or it can be measured several times after a certain number of ablation. For example, the dynamic contact resistance is measured 5 times after every 10 ablation times.

[0081] For the dynamic contact resistance test module 30, as Figure 4 As shown, the circuit may include:

[0082] The positive electrode of the charging power supply DC is connected to one end of the charging switch K, the other end of the charging switch K is connected to one end of the resistor R, the other end of the resistor R is connected to one end of the Hall coil H, and the other end of the Hall coil H is used to be connected to the first end of the test circuit breaker to be tested; one end of the capacitor Rc is connected to the line between the resistor R and the Hall coil H, and the other end is connected to one end of the capacitor Cc and is respectively connected to the negative electrode of the charging power supply DC and the ground terminal, and the negative electrode of the charging power supply DC is also used to be connected to the second end of the test circuit breaker to be tested.

[0083] In this embodiment, a large current is connected in series in the circuit breaker contact loop, and the circuit breaker is operated to open and close. A large current of more than 100A is generated in the circuit. The current in the circuit, the voltage at both ends of the circuit breaker port, and the circuit breaker travel curve are recorded during the whole process. The dynamic contact resistance curve of the circuit breaker during the whole process is obtained by using U / I, and combined with the travel curve, the change of contact resistance during the movement of the circuit breaker can be understood.

[0084] The data obtained from a single measurement of dynamic resistance include three time curves: break voltage, break current, and contact travel, such as Fig.10 As shown. The dynamic resistance-time curve can be calculated from the voltage and current waveforms by Ohm's law, as shown in Fig.11 By replacing the time axis with the stroke, the dynamic resistance-stroke curve can be obtained, which can more conveniently reflect the dynamic resistance information corresponding to different contact positions. The dynamic resistance-stroke curve is shown in Fig.12 As shown. Comparing the curve characteristics of the closing stage and the opening stage, it can be seen that the opening curve is smoother than the closing curve and shows an obvious segmentation rule: the dynamic resistance is stable when the main contact and arc contact are in contact, and the dynamic resistance shows a jump peak when the main contact is separated. The dynamic resistance is stable during the arc contact contact stage, and the resistance value jumps to exceed the range when it is separated. Due to the impact vibration during the closing process, the closing curve shows obvious resistance fluctuations and large measurement dispersion as a whole.

[0085] Typical dynamic resistance-travel curve in the opening stage is as follows: Fig.13 As shown in the figure, as the contact stroke increases, according to the characteristics of dynamic resistance change, it is divided into two stages. The first is the main contact stage, where the dynamic resistance is maintained at a relatively low level, corresponding to the parallel value of the actual contact main contact and arc contact resistance. Since the main contact resistance is much smaller than the arc contact resistance, it reflects the main contact resistance value; then the dynamic resistance value shows a significant jump, and with this as the dividing point, the latter stage is called the arc contact stage. At this time, the main contact has been completely separated, reflecting the arc contact resistance value. When the resistance value continues to rise to infinity, it appears to be out of range. At this time, the arc contact is completely separated, and the tripping action is completed. The definition based on the characteristics of the dynamic resistance curve is as follows: Fig.13The five parameters shown are: 1) The total contact stroke Lc, i.e., the contact stroke corresponding to the separation of the arc contact on the dynamic resistance-stroke curve, in mm. 2) The main contact stage stroke Lm, the stroke corresponding to the main contact stage dynamic resistance-stroke curve, in mm. 3) The arc contact stage stroke La, the stroke corresponding to the arc contact stage dynamic resistance-stroke curve, in mm. 4) The main contact resistance Rm, the average value of the dynamic resistance of the main contact stage, in μΩ. 5) The arc contact resistance Ra, the average value of the dynamic resistance of the arc contact stage, in μΩ.

[0086] like Fig.14 As shown in the figure, as the test current increases with 0.5kA, 1kA and 2kA, the reason why the resistance value of the arc contact stage of the dynamic resistance curve decreases is that the contact surface of the contact is usually covered by some materials with poor conductivity (called surface film), which increases the contact resistance. Increasing the test current will increase the contact temperature, and when the temperature rises to a certain level, the contact material will soften. This will have two effects: one is that it can destroy the surface film of the contact; the other is that it can reduce the yield strength of the contact point. They will increase the contact area of ​​the contact and thus reduce the contact resistance. When the temperature reaches the melting point of the contact material, the contact surface will be covered with a metal molten film, which will further reduce the contact resistance; as the test current increases, the reason why the fluctuation degree of the arc contact stage curve of the dynamic resistance curve decreases is that the large test current will generate a greater electromagnetic force, which will increase the mechanical pressure between the moving arc contact finger and the static arc contact finger, so that the electrical contact is more stable and the resistance curve is more stable.

[0087] Since the dynamic resistance curve under large test current is smoother, the measurement repeatability is better, and the resistance value is close to the true value, further parameter calculation is performed based on the 2kA test data.

[0088] Furthermore, the present invention also provides a simulated ablation test method for a filter bank circuit breaker. The test method is implemented based on the simulated ablation test platform for the filter bank circuit breaker described in the above embodiments. The method comprises:

[0089] Determine the allowable breaking ablation times and the allowable closing erosion times that can make the circuit breaker electrical life reach the life limit;

[0090] Using the simulated breaking and ablation module 10 of the simulated ablation test platform of the filter group circuit breaker, within the range of the allowed breaking and ablation times, the simulated opening operation is used to accelerate the ablation of the test circuit breaker contacts;

[0091] Or, using the simulated closing erosion module 20 of the simulated ablation test platform of the filter bank circuit breaker, within the range of the allowable closing erosion times, simulate the closing operation to accelerate the erosion of the test circuit breaker contacts;

[0092] The dynamic contact resistance test module 30 of the filter bank circuit breaker simulation ablation test platform is used to monitor the voltage of the contacts, the current flowing through the contacts and the travel signal during the opening or closing process of the test circuit breaker to determine the dynamic change of the contact resistance.

[0093] In one embodiment, determining the allowable number of interruption ablation times that can make the electrical life of the circuit breaker reach the life limit includes:

[0094] Use the following calculation formula to determine the allowable breaking and burning times of the circuit breaker:

[0095]

[0096] Among them, N s Used to characterize the allowable breaking and burning times of the circuit breaker, I s Used to characterize breaking current.

[0097] In this embodiment, since the life of a normal circuit breaker degrades slowly when breaking a small current, it is impossible to slowly burn it to the end of its life with a small current under laboratory conditions. Therefore, a larger current is used to perform an accelerated burning test to simulate the burning of an in-service circuit breaker. Domestic circuit breaker manufacturers have conducted a large number of breaking tests on SF6 circuit breakers and obtained the relationship curve between the allowable breaking times and the breaking current of the above-mentioned circuit breaker.

[0098] The maximum breaking current of the simulated ablation test is 75% of the rated short-circuit current, i.e. 30kA. Set different ablation currents and calculate the number of ablation times under the corresponding current according to the above formula, so that the electrical life of each phase reaches the life limit after the ablation test.

[0099] In one embodiment, the closing corrosion can be ablated by a 20kA current, the number of ablation is 200 times, and 5 dynamic resistance measurements are performed after every 10 ablation times. 200 times can be the average value of several devices tested. In another embodiment, in order to accurately determine the allowable closing corrosion times that can make the electrical life of the circuit breaker reach the life limit, it can be achieved in the following way:

[0100] According to the report of C2 test of circuit breaker, determine the ablation energy in C2 test of test circuit breaker;

[0101] The arc burning time is tested every M times, and the current during the arc burning time after the current surge is integrated to obtain the charge transferred each time by the arc;

[0102] When the accumulated arc transfer charge of ablation is equal to the energy of ablation during the C2 level test, the allowable number of closing erosions is confirmed.

[0103] In one embodiment, when accelerating the ablation of the test circuit breaker contacts using the simulated breaking ablation module 10, a timing control unit is used to control the sequence of each circuit breaker;

[0104] During one ablation process, the working states of each circuit breaker in the simulated opening and closing ablation module 10 include: first, the protective circuit breaker and the test circuit breaker are in the closed state, the closing circuit breaker is in the open state, the transformer charges the capacitor, and when the voltage reaches a predetermined value, the charging is stopped; then, the closing circuit breaker is actuated, the circuit is connected, the states of the test circuit breaker and the protective circuit breaker remain unchanged, and a power frequency attenuation current appears in the circuit; finally, after a set delay, the test circuit breaker is opened, the closing circuit breaker and the protective circuit breaker are in the closed state, an arc is generated in the arc extinguishing chamber of the test circuit breaker, and the arc is extinguished after the current passes through zero.

[0105] The circuit breaker dynamic contact resistance tester is based on the electrical contact theory. It applies a strong current to the moving and static contacts of the circuit breaker. During the entire opening and closing process of the circuit breaker, it measures the voltage of the contacts, the current flowing through the contacts, and the stroke signal, obtains the curve of the contact resistance and stroke changing with time, extracts the corresponding characteristic parameters such as the total contact stroke of the contact, the stage stroke of the main contact, the stage stroke of the arc contact, the main contact resistance, and the arc contact resistance, and evaluates the contact state of the arc contact of the high-voltage circuit breaker. For example, as the degree of arc contact ablation increases, the difference between the inner and outer diameters of the moving and static arc contacts increases, the surface becomes uneven, and the corresponding arc contact dynamic contact resistance curve fluctuates more, the average dynamic contact resistance value increases, and the contact will also ablate and shorten, and its contact stroke will continue to decrease, and then decide whether to carry out maintenance on the circuit breaker. Therefore, based on the simulated ablation test platform and test method of the filter group circuit breaker provided by this scheme, the contact life of the filter group circuit breaker can be effectively evaluated.

[0106] The modules or units in the device of the embodiment of the present invention can be combined, divided and deleted according to actual needs. The above disclosure is only the preferred embodiment of the present invention, and of course it cannot be used to limit the scope of the rights of the present invention. Those skilled in the art can understand that all or part of the processes of the above embodiment are implemented, and the equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A simulated ablation test platform for filter bank circuit breaker, characterized in that: include: Simulation module for breaking ablation, simulation module for closing erosion and dynamic contact resistance test; The simulated breaking and ablation module is used to connect in series the test circuit breaker to be tested, and simulate the opening operation to accelerate the ablation of the test circuit breaker contacts; The simulated closing erosion module is used to connect in series the test circuit breaker to be tested and simulate the closing operation to accelerate the ablation of the test circuit breaker contacts; The dynamic contact resistance test module is used to be connected to both ends of the test circuit breaker to be tested, and monitor the voltage of the contacts, the current flowing through the contacts and the travel signal during the opening or closing process of the test circuit breaker to determine the dynamic change of the contact resistance.

2. The simulated ablation test platform for filter bank circuit breaker according to claim 1, characterized in that: The circuit for simulating the breaking and ablation module comprises: One end of the switches K1 and K2 are both connected to the three-phase alternating current, and the other ends are both connected to the thyristor unit. One end of the resistor R1 is connected to the thyristor unit, and the other end is connected to the first end of the primary coil of the transformer. One end of the resistor R2 is respectively connected to the thyristor unit and the second end of the primary coil of the transformer, and the other end of the resistor R2 is connected to the first end of the primary coil of the transformer. One end of the resistor R3 is connected to the first end of the secondary coil of the transformer, and the other end is connected to the positive electrode of the diode D1. The negative electrode of the diode is connected to one end of the inductor L1. The other end of the inductor L1 is connected to one end of the protection circuit breaker QF1. The other end of the protection circuit breaker QF1 is connected to one end of the closing circuit breaker QF2. The other end of the closing circuit breaker QF2 is used to be connected to the first end of the test circuit breaker QF to be tested. One end of the capacitor group C1 is connected to the negative electrode of the diode D1, and the other end is connected to the second end of the secondary coil of the transformer. The second end of the secondary coil of the transformer is also used to be connected to the second end of the test circuit breaker QF to be tested.

3. The simulated ablation test platform for filter bank circuit breaker according to claim 2, characterized in that: The simulated breaking and ablation module also includes: a timing control unit, which is used to control the actions of each circuit breaker in the simulated breaking and ablation module according to a preset sequence.

4. The simulated ablation test platform for filter bank circuit breaker according to claim 1, characterized in that: The circuit of the simulated closing erosion module includes: A first end of the power supply AC is connected to the anode of the diode D2, one end of the switch K3 is connected to the cathode of the diode D2, and the other end is connected to one end of the resistor R4, the other end of the resistor R4 is connected to one end of the inductor L2, the other end of the inductor L2 is connected to one end of the switch K4, the other end of the switch K4 is used to be connected to the first end of the test circuit breaker QF to be tested, one end of the capacitor C2 is connected to the line between the switch K3 and the resistor R4, and the other end is connected to the second end of the power supply AC, and the second end of the power supply AC is also used to be connected to the second end of the test circuit breaker QF to be tested.

5. The simulated ablation test platform for filter bank circuit breaker according to claim 1, characterized in that: The circuit of the dynamic contact resistance test module includes: The positive electrode of the charging power supply DC is connected to one end of the charging switch K, the other end of the charging switch K is connected to one end of the resistor R, the other end of the resistor R is connected to one end of the Hall coil H, and the other end of the Hall coil H is used to be connected to the first end of the test circuit breaker to be tested; one end of the capacitor Rc is connected to the line between the resistor R and the Hall coil H, and the other end is connected to one end of the capacitor Cc and is respectively connected to the negative electrode of the charging power supply DC and the ground terminal, and the negative electrode of the charging power supply DC is also used to be connected to the second end of the test circuit breaker to be tested.

6. The simulated ablation test platform for filter bank circuit breaker according to claim 2, characterized in that: The test circuit breaker to be tested is an SF6 high-voltage circuit breaker with a rated closing short-circuit current of 63kA; the opening action time of the test circuit breaker is 32.5ms-33ms, and the closing action time of the closing circuit breaker is 42.8ms-43ms.

7. A simulated ablation test method for a filter bank circuit breaker, characterized in that: The test method is implemented based on the simulated ablation test platform of the filter bank circuit breaker according to claims 1-6, and the method comprises: Determine the allowable breaking ablation times and the allowable closing erosion times that can make the circuit breaker electrical life reach the life limit; Using the simulated breaking and ablation module of the simulated ablation test platform of the filter group circuit breaker, within the range of the allowable breaking and ablation times, simulate the opening operation to accelerate the ablation of the test circuit breaker contacts; Or, using the simulated closing erosion module of the simulated ablation test platform of the filter bank circuit breaker, simulate the closing operation within the range of the allowable closing erosion times to accelerate the erosion of the test circuit breaker contacts; The dynamic contact resistance test module of the filter bank circuit breaker simulation ablation test platform is used to monitor the contact voltage, current flowing through the contact and travel signal during the opening or closing process of the test circuit breaker to determine the dynamic change of the contact resistance.

8. The simulated ablation test method for a filter bank circuit breaker according to claim 7, characterized in that: The determination of the allowable breaking and ablation times that can make the electrical life of the circuit breaker reach the life limit includes: Use the following calculation formula to determine the allowable breaking and burning times of the circuit breaker: Among them, N s Used to characterize the allowable breaking and burning times of the circuit breaker, I s Used to characterize breaking current.

9. The simulated ablation test method for a filter bank circuit breaker according to claim 7, characterized in that: The determination of the allowable closing corrosion times that can make the electrical life of the circuit breaker reach the life limit includes: According to the report of C2 test of circuit breaker, determine the ablation energy in C2 test of test circuit breaker; The arc burning time is tested every M times, and the current during the arc burning time after the current surge is integrated to obtain the charge transferred each time by the arc; When the accumulated arc transfer charge of ablation is equal to the energy of ablation during the C2 level test, the allowable number of closing erosions is confirmed.

10. The simulated ablation test method for a filter bank circuit breaker according to claim 7, characterized in that: When accelerating the ablation of the test circuit breaker contacts by using the simulated breaking ablation module, a timing control unit is used to control the sequence of each circuit breaker; During one ablation process, the working states of each circuit breaker in the simulated opening and closing ablation module include: first, the protective circuit breaker and the test circuit breaker are in the closed state, the closing circuit breaker is in the open state, the transformer charges the capacitor, and when the voltage reaches a predetermined value, the charging stops; then, the closing circuit breaker is actuated, the circuit is connected, the states of the test circuit breaker and the protective circuit breaker remain unchanged, and a power frequency attenuation current appears in the circuit; finally, after a set delay, the test circuit breaker is opened, the closing circuit breaker and the protective circuit breaker are in the closed state, an arc is generated in the arc extinguishing chamber of the test circuit breaker, and the arc is extinguished after the current passes through the zero point.

Images