Controllable oscillation DC circuit breaker test system

Abstract

The invention relates to a controllable oscillation DC circuit breaker test system, and belongs to the technical field of DC circuit breakers. The system comprises a resonant capacitor connected in series and a charging interface used for being externally connected with a power supply, two ends of the resonant capacitor are connected with a to-be-tested branch in parallel, and the to-be-tested branch comprises a resonant inductor, a discharging switch and a to-be-tested interface used for being externally connected with a to-be-tested controllable oscillation direct current circuit breaker, the controllable oscillation direct-current circuit breaker further comprises current acquisition devices arranged on the branch to be tested and a main through-current branch and / or an oscillation branch of the controllable oscillation direct-current circuit breaker to be tested. The test system obtains the real-time state of a to-be-tested DC circuit breaker in real time through current acquisition devices arranged on a to-be-tested branch circuit and a main through-flow branch circuit and / or an oscillation branch circuit of the to-be-tested controllable oscillation DC circuit breaker, so as to accurately determine whether the breaking performance of the to-be-tested DC circuit breaker meets the expectation or not. And therefore, comprehensive verification of the breaking test of the controllable oscillation direct-current circuit breaker can be realized.

Description

Technical Field

[0001] The present invention relates to a test system for a controllable oscillating DC circuit breaker, belonging to the technical field of DC circuit breakers. Background Art

[0002] At present, a controllable oscillating DC circuit breaker includes a main current-carrying branch, an oscillating branch, a full-bridge controllable unit, and an energy dissipation branch. As a new product, how to reliably verify its working characteristics is a difficult problem in the industry.

[0003] The patent document with publication number CN116718908A discloses a test circuit for a DC circuit breaker. The test circuit includes a capacitor charging circuit and a test circuit. The test circuit includes a first switch, an inductor, a diode, and a capacitor. The first switch, the inductor, the diode, and the to-be-tested DC circuit breaker are connected in series between both ends of the capacitor; the conduction direction of the diode is the same as the discharging direction of the capacitor. When the inductor current oscillates through zero for the first time, the diode cuts off to prevent the current from oscillating repeatedly; the capacitor charging circuit is connected to the capacitor and used to charge the capacitor. After the charge of the capacitor meets the set value, the test of the DC circuit breaker can be carried out. At this time, the first switch can be controlled to close, so that the short-circuit current formed by the oscillating discharge of the capacitor and the inductor causes the circuit breaker to act, and thus the opening characteristics of the DC circuit breaker can be obtained. This solution tests the opening characteristics of the DC circuit breaker through the test circuit, thereby realizing the performance evaluation of the DC circuit breaker and avoiding safety problems during the use of the DC circuit breaker.

[0004] However, the conduction direction of the diode connected in series at both ends of the capacitor is the same as the discharging direction of the capacitor, so that the current passing through the DC circuit breaker is only the forward current of the resonant capacitor discharging in the forward direction. In actual applications, the current passing through the DC circuit breaker during the breaking process is positive and negative currents. Therefore, this test circuit cannot comprehensively verify the breaking test of the controllable oscillating DC circuit breaker.

[0005] The patent document with the publication number CN109031106A discloses a breaking test device for a hybrid DC circuit breaker. The test device includes a charging power supply branch, a resonant capacitor, a resonant inductor, a resonant control switch, a discharging branch, and positive and negative connection terminals for connecting a hybrid DC circuit breaker specimen. The charging power supply branch and the resonant capacitor are connected in parallel and form first and second parallel connection points, and the first and second parallel connection points are correspondingly connected to the positive and negative connection terminals; the resonant inductor and the resonant control switch are serially arranged between the first parallel connection point and the positive connection terminal and / or between the second parallel connection point and the negative connection terminal; the discharging branch is connected in parallel across the two ends of the resonant capacitor, and the discharging branch includes a parallel-connected discharging branch and a bypass branch. A dissipative device and a discharging switch are serially arranged in the discharging branch, and a grounding switch is serially arranged in the bypass branch. In this solution, during the residual energy discharging process of the DC circuit breaker, it first discharges through the discharging branch, and after a delay period, it directly discharges to the ground, so that the residual energy in the circuit breaker is discharged more completely and the test process is safer.

[0006] However, in the test process of this solution, the real-time state of the to-be-tested DC circuit breaker cannot be obtained in real time. Therefore, it is difficult to accurately determine whether the breaking performance of the to-be-tested DC circuit breaker meets the expectations, and this test device also cannot achieve a comprehensive verification of the breaking test of the controllable oscillation DC circuit breaker. Summary of the Invention

[0007] The object of the present invention is to provide a controllable oscillation DC circuit breaker test system to solve the problem that the existing breaking test for the controllable oscillation DC circuit breaker is not comprehensive.

[0008] To achieve the above object, the solution of the present invention includes: A controllable oscillation DC circuit breaker test system of the present invention includes a series-connected resonant capacitor and a charging interface for connecting to an external power supply. A to-be-tested branch is connected in parallel across the two ends of the resonant capacitor. The to-be-tested branch includes a series-connected resonant inductor, a discharging switch, and a to-be-tested interface for connecting to a to-be-tested controllable oscillation DC circuit breaker; it also includes a current acquisition device arranged on the to-be-tested branch and on the main current-carrying branch and / or the oscillation branch of the to-be-tested controllable oscillation DC circuit breaker.

[0009] Further, it also includes a charging switch for controlling the charging of the resonant capacitor. The charging switch is serially connected with the resonant capacitor and the charging interface.

[0010] Further, a discharging branch is also connected in parallel across the two ends of the resonant capacitor. The discharging branch is connected in parallel with the to-be-tested branch and includes a series-connected discharging resistor and a discharging switch.

[0011] Further, the connection point between the negative terminal of the charging interface and the resonant capacitor and the connection point between the negative terminal of the charging interface and the to-be-tested branch are both grounded.

[0012] Advantages of the Present Invention: The present invention is a pioneering invention, which provides a test system for a controllable oscillating DC circuit breaker, including a series-connected resonant capacitor and a charging interface for connecting an external power supply. Both ends of the resonant capacitor are connected in parallel with a branch to be tested, and the branch to be tested includes a series-connected resonant inductor, a discharge switch, and a test interface for connecting an external controllable oscillating DC circuit breaker to be tested; it also includes a current acquisition device arranged on the branch to be tested and on the main current-carrying branch and / or the oscillating branch of the controllable oscillating DC circuit breaker to be tested. The test system charges the resonant capacitor through the power supply connected to the charging interface. After the charging is completed, the discharge switch is closed to discharge the resonant capacitor. The resonant capacitor and the resonant inductor alternately store energy to form an oscillation process, that is, the short-circuit current formed by the oscillating discharge of the resonant capacitor and the resonant inductor causes the external controllable oscillating DC circuit breaker to operate, so as to obtain the opening characteristics of the circuit breaker to be tested. On this basis, through the current acquisition device arranged on the branch to be tested and on the main current-carrying branch of the controllable oscillating DC circuit breaker to be tested, or through the current acquisition device arranged on the branch to be tested and on the oscillating branch of the controllable oscillating DC circuit breaker to be tested, or through the current acquisition device arranged on the branch to be tested and on the main current-carrying branch and the oscillating branch of the controllable oscillating DC circuit breaker to be tested, the real-time state of the DC circuit breaker to be tested is obtained in real time, so as to accurately determine whether the breaking performance of the DC circuit breaker to be tested meets the expectations, and further realize the comprehensive verification of the breaking test of the controllable oscillating DC circuit breaker. Description of the Drawings

[0013] Figure 1 is the topological structure diagram of the test system for the controllable oscillating DC circuit breaker; Figure 2 is the topological structure diagram of the test system with the controllable oscillating DC circuit breaker to be tested connected; Figure 3 is the topological structure diagram of the H-bridge module; Figure 4 is the test flow chart of the test system for the controllable oscillating DC circuit breaker; Figure 5 is the waveform diagram of the breaking current of the controllable oscillating DC circuit breaker during the test.

[0014] Description of the Reference Numerals: A1, the first terminal; A2, the second terminal; C0, the zero - numbered capacitor; C1, the resonant capacitor; C2, the oscillation capacitor; CT1, the first current transformer; CT2, the second current transformer; CT3, the third current transformer; D1, the first diode; D2, the second diode; D3, the third diode; D4, the fourth diode; DC +, the positive terminal; DC -, the negative terminal; K1, the charging switch; K2, the discharging switch; K3, the discharging resistor switch; L1, the resonant inductor; L2, the oscillation inductor; QF, the quick - opening switch; QH, the quick - closing switch; R0, the zero - numbered resistor; R1, the discharging resistor; T1, the first transistor; T2, the second transistor; T3, the third transistor; T4, the fourth transistor. Specific implementation mode

[0015] To solve the problems in the background technology, the present invention provides a controllable oscillation DC breaker test system. By obtaining the total current of the resonant capacitor discharge, the current passing through the oscillation inductor, and the current passing through the main current - conducting branch of the to - be - tested controllable oscillation DC breaker, the real - time state of the to - be - tested DC breaker is reflected, so as to accurately determine whether the breaking performance of the to - be - tested DC breaker meets the expectation, and further realize a comprehensive verification of the breaking test of the controllable oscillation DC breaker.

[0016] To make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0017] Embodiment 1 of a controllable oscillation DC breaker test system: A controllable oscillation DC breaker test system includes a series - connected resonant capacitor and a charging interface for connecting to an external power supply. Both ends of the resonant capacitor are connected in parallel with a to - be - tested branch. The to - be - tested branch includes a series - connected resonant inductor, a discharging switch, and a to - be - tested interface for connecting to a to - be - tested controllable oscillation DC breaker; it also includes current acquisition devices arranged on the to - be - tested branch and the main current - conducting branch of the to - be - tested controllable oscillation DC breaker.

[0018] Among them, the current passing through the oscillation inductor is obtained by subtracting the current passing through the main current - conducting branch from the current passing through the to - be - tested branch; the current passing through the to - be - tested branch is the total current of the resonant capacitor discharge.

[0019] The present invention charges the resonant capacitor through an external power supply of the charging interface, and discharges the resonant capacitor by closing the discharge switch after charging. The resonant capacitor and the resonant inductor alternately store energy to form an oscillation process, that is, the short-circuit current formed by the oscillation discharge of the resonant capacitor and the resonant inductor causes the external controllable oscillation DC circuit breaker to be tested to operate, thereby obtaining the breaking characteristics of the circuit breaker to be tested, and also obtaining the total current discharged by the resonant capacitor and the current passing through the main current branch of the controllable oscillation DC circuit breaker to be tested in real time through a current acquisition device arranged on the branch to be tested and the main current branch of the controllable oscillation DC circuit breaker to be tested, so as to obtain the real-time state of the DC circuit breaker to be tested, thereby accurately determining whether the breaking performance of the DC circuit breaker to be tested meets expectations, and finally realizing a comprehensive verification of the breaking test of the controllable oscillation DC circuit breaker.

[0020] Specifically, it also includes a charging switch for controlling the charging of the resonant capacitor, and the charging switch is connected in series with the resonant capacitor and the charging interface.

[0021] In order to facilitate the control of the charging of the resonant capacitor, a charging switch is also connected in series on the circuit connecting the resonant capacitor and the charging interface in series. The charging switch is closed to enable the power source external to the charging interface to charge the resonant capacitor, and the charging switch is opened to terminate the charging of the resonant capacitor by the power source external to the charging interface.

[0022] Specifically, a discharge branch is connected in parallel between both ends of the resonant capacitor, the discharge branch is connected in parallel with the branch to be measured, and the discharge branch includes a discharge resistor and a discharge switch connected in series.

[0023] After the DC circuit breaker to be tested (the controllable oscillation DC circuit breaker to be tested) is disconnected, the present invention closes the discharge switch and releases the residual pressure through the discharge resistor, thereby solving the problem of residual energy discharge in the test system and improving the test efficiency while ensuring safety and reliability.

[0024] Specifically, a connection point between the negative terminal of the charging interface and the resonant capacitor, and a connection point between the negative terminal and the branch to be tested are both grounded.

[0025] After the DC circuit breaker to be tested (the controllable oscillation DC circuit breaker to be tested) is disconnected, the present invention closes the discharge switch to discharge to the ground through the discharge resistor, thereby solving the problem of residual energy discharge in the test system and improving the test efficiency while ensuring safety and reliability.

[0026] Embodiment 2 of a controllable oscillation DC circuit breaker test system: A controllable oscillation DC circuit breaker test system includes a series-connected resonant capacitor and a charging interface for an external power supply. Both ends of the resonant capacitor are connected in parallel with a branch under test. The branch under test includes a series-connected resonant inductor, a discharge switch, and a test interface for externally connecting a controllable oscillation DC circuit breaker under test. It also includes current acquisition devices arranged on the branch under test and the oscillation branch of the controllable oscillation DC circuit breaker under test.

[0027] Among them, the current passing through the oscillation branch specifically refers to the current passing through the oscillation inductor; the current passing through the branch under test is the total current of the resonant capacitor discharging; the current passing through the main current-carrying branch is obtained by subtracting the current passing through the oscillation inductor from the current passing through the branch under test.

[0028] In the present invention, the power supply externally connected through the charging interface charges the resonant capacitor. After the charging is completed, the discharge switch is closed to make the resonant capacitor discharge. The resonant capacitor and the resonant inductor alternately store energy, forming an oscillation process, that is, the short-circuit current formed by the oscillatory discharge of the resonant capacitor and the resonant inductor causes the externally connected controllable oscillation DC circuit breaker under test to act, thereby obtaining the opening characteristics of the circuit breaker under test. Also, the total current of the resonant capacitor discharging and the current passing through the oscillation branch of the controllable oscillation DC circuit breaker under test are obtained in real time through the current acquisition devices arranged on the branch under test and the oscillation branch of the controllable oscillation DC circuit breaker under test, so as to obtain the real-time state of the DC circuit breaker under test, and then accurately determine whether the breaking performance of the DC circuit breaker under test meets the expectations, and finally realize a comprehensive verification of the breaking test of the controllable oscillation DC circuit breaker.

[0029] Specifically, it further includes a charging switch for controlling the charging of the resonant capacitor. The charging switch is connected in series with the resonant capacitor and the charging interface.

[0030] For facilitating the control of the charging of the resonant capacitor, a charging switch is also connected in series on the line where the resonant capacitor is connected in series with the charging interface. The charging process of the power supply externally connected through the charging interface to the resonant capacitor is realized by closing the charging switch, and the charging process of the power supply externally connected through the charging interface to the resonant capacitor is ended by opening the charging switch.

[0031] Specifically, a discharge branch is also connected in parallel at both ends of the resonant capacitor. The discharge branch is connected in parallel with the branch under test. The discharge branch includes a series-connected discharge resistor and a discharge switch.

[0032] In the present invention, after the breaking of the DC circuit breaker under test (controllable oscillation DC circuit breaker under test) is completed, the discharge switch is closed, and the residual voltage is released through the discharge resistor, solving the problem of discharging the residual energy in the test system, and improving the test efficiency while ensuring safety and reliability.

[0033] Specifically, the connection point between the negative terminal of the charging interface and the resonant capacitor, and the connection point between the negative terminal and the branch under test are both grounded.

[0034] After the DC circuit breaker under test (the controllable oscillating DC circuit breaker under test) is disconnected, the discharge switch is closed, and the energy is discharged to the ground through a discharge resistor, solving the problem of discharging the residual energy in the test system, improving the test efficiency while ensuring safety and reliability.

[0035] Embodiment 3 of a test system for a controllable oscillating DC circuit breaker: A test system for a controllable oscillating DC circuit breaker includes a series-resonant capacitor and a charging interface for connecting to an external power supply. Both ends of the resonant capacitor are connected in parallel with a branch under test. The branch under test includes a series-connected resonant inductor, a discharge switch, and a test interface for connecting to the controllable oscillating DC circuit breaker under test; it also includes current acquisition devices arranged on the branch under test, on the main current-carrying branch of the controllable oscillating DC circuit breaker under test, and on the oscillating branch of the controllable oscillating DC circuit breaker under test.

[0036] Among them, the current passing through the oscillating branch specifically refers to the current passing through the oscillating inductor; the current passing through the branch under test specifically refers to the total current of the resonant capacitor discharging.

[0037] In the present invention, the power supply connected externally through the charging interface charges the resonant capacitor. After the charging is completed, the discharge switch is closed to discharge the resonant capacitor. The resonant capacitor and the resonant inductor alternately store energy, forming an oscillation process, that is, the short-circuit current formed by the oscillating discharge of the resonant capacitor and the resonant inductor causes the external controllable oscillating DC circuit breaker under test to act, thereby obtaining the opening characteristics of the circuit breaker under test. It also obtains the total current of the resonant capacitor discharging, the current passing through the main current-carrying branch of the controllable oscillating DC circuit breaker under test, and the current passing through the oscillating branch of the controllable oscillating DC circuit breaker under test in real time through the current acquisition devices arranged on the branch under test, on the main current-carrying branch of the controllable oscillating DC circuit breaker under test, and on the oscillating branch of the controllable oscillating DC circuit breaker under test, so as to obtain the real-time state of the DC circuit breaker under test, and then accurately determine whether the breaking performance of the DC circuit breaker under test meets the expectations, and finally realize the comprehensive verification of the breaking test of the controllable oscillating DC circuit breaker.

[0038] Among them, the current acquisition device can be selected as a current sensor or a current transformer according to needs.

[0039] Specifically, it further includes a charging switch for controlling the charging of the resonant capacitor. The charging switch is connected in series with the resonant capacitor and the charging interface.

[0040] To facilitate the control of the charging of the resonant capacitor, a charging switch is also connected in series on the line where the resonant capacitor is connected in series with the charging interface. The charging process of the power supply connected externally through the charging interface to the resonant capacitor is realized by closing the charging switch, and the charging process of the power supply connected externally through the charging interface to the resonant capacitor is ended by opening the charging switch.

[0041] Specifically, a discharge branch is also connected in parallel at both ends of the resonant capacitor. The discharge branch is connected in parallel with the branch to be measured, and the discharge branch includes a series-connected discharge resistor and a discharge switch.

[0042] After the DC circuit breaker to be measured (the controllable oscillating DC circuit breaker to be measured) is disconnected, the discharge switch is closed, and the residual voltage is released through the discharge resistor, solving the problem of discharging the residual energy in the test system and improving the test efficiency while ensuring safety and reliability.

[0043] Specifically, the connection point between the negative terminal of the charging interface and the resonant capacitor and the connection point between the negative terminal and the branch to be measured are both grounded.

[0044] After the DC circuit breaker to be measured (the controllable oscillating DC circuit breaker to be measured) is disconnected, the discharge switch is closed, and the charge is discharged to the ground through the discharge resistor, solving the problem of discharging the residual energy in the test system and improving the test efficiency while ensuring safety and reliability.

[0045] The controllable oscillating DC circuit breaker test system, as Figure 1 shown, includes a series-connected resonant capacitor C1, a resonant inductor L1, a discharge switch K2, a third current transformer CT3, and an interface to be measured. The two ends of the resonant capacitor C1 are respectively connected to the positive terminal DC+ and the negative terminal DC- of the charging interface. The charging interface is used to connect an external power supply to charge the resonant capacitor C1 through the external power supply.

[0046] Among them, the power supply for charging the resonant capacitor C1 is a DC power supply, and this DC power supply is the DC power output after rectifying 380V alternating current by a rectifier. Among them, the rectifier is the rectifier of the charging cabinet.

[0047] On this basis, as Figure 2 shown, the test system further includes a charging switch K1. The charging switch K1 is arranged between the resonant capacitor C1 and the positive terminal DC+ of the charging interface. Of course, it can also be arranged between the resonant capacitor C1 and the negative terminal DC- of the charging interface. The charging of the resonant capacitor C1 by the power supply is realized by closing the charging switch K1, and the charging of the resonant capacitor C1 is ended by opening the charging switch K1.

[0048] Among them, the interface to be measured is used to connect the controllable oscillating DC circuit breaker to be measured. The first terminal A1 and the second terminal A2 of the interface to be measured are respectively connected to both ends of the main current-carrying branch of the DC circuit breaker.

[0049] The controllable oscillating DC circuit breaker to be measured includes a main current-carrying branch, a transfer branch, and a power-consuming branch. The main current-carrying branch includes a line in series with a fast disconnection switch QF. The transfer branch includes a line in series with an oscillating inductor L2, an oscillating capacitor C2, and an H-bridge module. The power-consuming branch includes a line provided with a lightning arrester.

[0050] Among them, the main current-carrying branch and the transfer branch are in parallel, and both ends of the oscillation capacitor C2 after being connected in series with the H-bridge module are respectively connected to both ends of the energy-consuming branch. The series-connected oscillation inductor L2 and oscillation capacitor C2 form an oscillation branch, and the H-bridge module serves as a full-bridge controllable unit. A fast-switching switch QH for putting into the transfer branch is also connected in series on the transfer branch.

[0051] The first current transformer CT1 is arranged on the main current-carrying branch for obtaining the current passing through the main current-carrying branch; the second current transformer CT2 is arranged on the oscillation branch for obtaining the current passing through the oscillation inductor L2.

[0052] The H-bridge module includes 4 power electronic devices, a zero capacitor C0 and a zero resistor R0. The 4 power electronic devices and the zero capacitor C0 form a full-bridge structure. The 4 power electronic devices are IGBTs. As Figure 3 shown, the first transistor T1 (hereinafter simply referred to as T1), the second transistor T2 (hereinafter simply referred to as T2), the third transistor T3 (hereinafter simply referred to as T3), the fourth transistor T4 (hereinafter simply referred to as T4), the first diode D1 (hereinafter simply referred to as D1), the second diode D2 (hereinafter simply referred to as D2), the third diode D3 (hereinafter simply referred to as D3), the fourth diode D4 (hereinafter simply referred to as D4) and the zero capacitor C0 form a full-bridge structure. Both ends of the zero capacitor C0 are respectively connected to the positive and negative terminals of another charging interface. A zero resistor R0 is connected in series between the positive terminal of the zero capacitor C0 and the positive terminal of this charging interface or between the zero capacitor C0 and the negative terminal DC- of this charging interface. The positive and negative poles of the zero capacitor C0 are opposite to the direction of the positive current.

[0053] A discharge branch is also connected in parallel at both ends of the resonant capacitor C1. The discharge branch includes a series-connected discharge resistor R1 and a discharge switch K3. After the tested DC circuit breaker is disconnected, the discharge switch is closed, and the residual voltage is released through the discharge resistor, solving the problem of discharging the residual energy in the test system, and improving the test efficiency while ensuring safety and reliability.

[0054] The connection point between the negative terminal DC- of the charging interface and the resonant capacitor C1 and the connection point between the negative terminal DC- of this charging interface and the second wiring terminal A2 of the tested interface are both grounded. After the tested DC circuit breaker is disconnected, the discharge switch is closed, and the discharge is carried out to the ground through the discharge resistor, solving the problem of discharging the residual energy in the test system, and improving the test efficiency while ensuring safety and reliability.

[0055] This test system is used to test the ability of a controllable oscillating DC circuit breaker to interrupt current. The test system charges the resonant capacitor C1 through a rectifier in the charging cabinet from an AC power supply (such as a 380V power supply) externally connected through a charging interface, that is, the charging cabinet charges the resonant capacitor C1. After charging is completed, the charging switch K1 is disconnected, the discharging switch K2 is closed, and the line current starts to increase (that is, the current measured by the third current transformer CT3 starts to increase). After the current detected by the first current transformer CT1 is greater than the current set value Iset, the power devices of the H-bridge module are controlled to turn off. When the current detected by the first current transformer CT1 is zero, it indicates that the fast-opening switch QF is completely disconnected.

[0056] While issuing a tripping command for the fast-opening switch QF, the fast-closing switch QH is controlled to close. And after issuing a tripping command for the fast-opening switch QF, within the maximum first set time S1 of delay, after receiving the intermediate position signal of the fast-opening switch QF, T1 / T4 conducts, and the resonant current (transfer branch current, that is, the current measured by the second current transformer CT2) flows through the H-bridge module from T1-C0-T4, and the resonant capacitor C1 discharges positively. When the resonant current passes through zero in the positive direction and becomes negative, T1 / T4 is turned off. After a second set time S2 of delay, T2 / T3 is conducted, and the resonant current flows through the H-bridge module from D2-C1-D3. When the resonant current passes through zero in the negative direction and becomes positive, T2 / T3 is turned off. After a second set time S2 of delay, T1 / T4 is conducted, and the resonant current flows through the H-bridge module from T1-C0-T4. When the resonant current passes through zero in the positive direction and becomes negative, T1 / T4 is turned off. After a second set time S2 of delay, T2 / T3 is conducted, and the resonant current flows through the H-bridge module from D2-C1-D3. When the resonant current passes through zero in the negative direction and becomes positive, T2 / T3 is turned off. After a second set time S2 of delay, T1 / T4 is conducted, and the resonant current flows through the H-bridge module from T1-C0-T4. When the resonant current passes through zero in the positive direction and becomes negative, T4 is turned off. After a second set time S2 of delay, T2 is conducted.

[0057] Among them, when the main branch current is zero, the fast-opening switch QF is completely disconnected.

[0058] Among them, the intermediate position signal of the fast-opening switch QF means that after the fast-opening switch QF is separated to a certain extent, the main current-carrying branch current transfers to the transfer branch. When T1 / T4 conducts and switches to T2 / T3 conduction, at this time, T1 commutates with D3, and T4 commutates with D2; when T2 / T3 conducts and switches to T1 / T4 conduction, at this time, D3 commutates with T1, and D2 commutates with T4.

[0059] During the process of controlling the H-bridge upper and lower switches to conduct alternately, the resonant current gradually rises, and the line current (i.e., the current measured by the third current transformer CT3) is turned off during the positive period of the resonant current. When the current in the fast disconnection switch QF is detected to be zero and the duration exceeds the third set time S3, it can be judged that the current in the mechanical switch (fast disconnection switch) passes through zero and extinguishes the arc and turns off.

[0060] Combined with the flowchart as shown in Figure 4 and the waveform diagram as shown in Figure 5 the following detailed description is given to the tripping control strategy of the controllable oscillating DC circuit breaker: After the control device receives the tripping command and detects that the line current passing through the resonant inductor L1 (i.e., the current measured by the third current transformer CT3) is a positive current, the tripping is completed according to the following control logic; First, issue the tripping command for the mechanical switch (fast disconnection switch QF) and the closing command for the fast closing switch QH; Within a maximum delay of 2.1 ms (the first set time S1), after receiving the mechanical switch intermediate position signal, first control T1 / T4 to conduct. After the zero crossing point of the positive current half-wave (resonant current) of the first cycle, turn off T1 / T4 simultaneously. After a dead time of 20 us (the second set time S2), turn on T2 / T3 simultaneously; When detecting the zero crossing point of the reverse current half-wave (resonant current) of the first cycle, turn off T2 / T3, and turn on T1 / T4 after a dead time of 20 us (the second set time S2); After detecting the zero crossing point of the positive current half-wave of the second cycle, turn off T1 / T4 simultaneously. After a dead time of 20 us (the second set time S2), turn on T2 / T3 simultaneously; After detecting the zero crossing point of the reverse current half-wave of the second cycle, turn off T2 / T3 simultaneously. After a dead time of 20 us (the second set time S2), turn on T1 / T4 simultaneously; After detecting the zero crossing of the positive current half-wave of the third cycle, turn off T4 simultaneously. After a dead time of 20 us (the second set time S2), turn on T2.

[0061] Figure 5 In the current waveform diagram of the upper part, the line current is shown by the black line, the main branch current is shown by the blue line, and the transfer branch current is shown by the red line; Figure 5 In the device disconnection schematic diagram of the lower part, the thick line represents the closing state of the fast disconnection switch QF and the conduction states of T1, T2, T3, and T4, and the corresponding thin line represents the off state of the fast disconnection switch QF and the off states of T1, T2, T3, and T4; the fast disconnection switch QF is represented by Sig_QF in Figure 5 and T1 is represented by FCS_T1 in Figure 5 and T2 is represented byFigure 5 It is represented by FCS_T2 in Figure 5 It is represented by FCS_T3 in Figure 5 It is represented by FCS_T4 in

[0062] During the process of controlling the H-bridge upper and lower transistors to conduct alternately within 2.5 cycles of the above resonance current, the resonance current gradually rises, and the line current is turned off during the positive period of the resonance current. When the current in the mechanical switch (main branch current) is detected to be zero and the duration exceeds the third set time S3, it can be determined that the current in the mechanical switch passes through zero and extinguishes the arc. When it is detected that the current in the mechanical switch passes through zero and turns off, continue to maintain T1 / T4 conduction. At this time, the line current has been transferred to the transfer branch. Until the zero crossing point of the resonance current is detected, turn off T4, maintain T1 conduction, and after a dead time of 20 us, turn on T2. The H-bridge is put into zero level. During the zero-level input process, when the line current is detected to be less than a certain value, and the current in the transfer branch is zero-crossed both positively and negatively, and the duration is 1000 us, T1 / T2 / T3 / T4 of the H-bridge module are all turned off.

[0063] If the zero crossing of the positive current half-wave in the 3rd cycle is not detected, then T1 / T2 / T3 / T4 of the H-bridge module are all turned off after the zero crossing point of the resonance current.

[0064] During the above control process, before the current in the mechanical switch passes through zero, if the zero crossing signal of the resonance current is not detected, report an abnormality, maintain the conduction state of the current upper and lower transistors, and do not conduct alternately.

[0065] A controllable oscillation DC circuit breaker test system of the present invention charges the resonance capacitor to a certain value through a charging cabinet, closes the discharge switch to generate a resonance current, can simulate the short-circuit current of the actual system, and can complete the breaking test of the controllable oscillation DC circuit breaker by controlling the on / off of the H-bridge module. By adjusting the parameters of the test system, a comprehensive verification of the breaking test of the DC circuit breaker can be achieved.

Claims

1. A controllable oscillation DC circuit breaker test system, characterized in that: The invention comprises a series resonant capacitor and a charging interface for an external power supply, wherein a branch to be tested is connected in parallel at both ends of the resonant capacitor, and the branch to be tested comprises a series resonant inductor, a discharge switch and a test interface for an external controllable oscillating DC circuit breaker to be tested; and also comprises a current acquisition device for being arranged on the branch to be tested and on the main current branch and / or oscillation branch of the controllable oscillating DC circuit breaker to be tested.

2. The controllable oscillation DC circuit breaker test system according to claim 1, characterized in that: It also includes a charging switch for controlling the charging of the resonant capacitor, and the charging switch is connected in series with the resonant capacitor and the charging interface.

3. The controllable oscillation DC circuit breaker test system according to claim 1 or 2, characterized in that: A discharge branch is connected in parallel at both ends of the resonant capacitor. The discharge branch is connected in parallel with the branch to be tested. The discharge branch includes a discharge resistor and a discharge switch connected in series.

4. The controllable oscillation DC circuit breaker test system according to claim 1, characterized in that: A connection point between the negative terminal of the charging interface and the resonant capacitor, and a connection point between the negative terminal and the branch to be tested are both grounded.

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