Direct-connection-preventing self-excitation resonance direct-current circuit breaker and economical control method thereof

Abstract

The invention discloses an anti-direct-connection self-excitation resonance direct-current circuit breaker and an economical control method thereof. The direct-current circuit breaker comprises a main branch, a transfer branch and an energy consumption branch, the transfer branch comprises a resonant capacitor, an anti-direct-connection voltage-controlled power electronic module and a pre-energy-storage capacitor module, and the anti-direct-connection voltage-controlled power electronic module comprises a first inductor, a second inductor and a bridge circuit. One end of the first inductor and one end of the second inductor are respectively connected with one bridge arm of the bridge circuit, the other end of the first inductor is connected with the other end of the second inductor and then is connected with the resonant capacitor, the pre-energy-storage capacitor module comprises two series capacitors, and the two series capacitors are integrally connected in parallel at the two ends of the bridge circuit. The second inductor is connected in parallel with a voltage probe used for voltage measurement, and the voltage probe is connected with the bridge circuit through the controller. The problem that the efficiency is reduced due to dead time is solved, an economical closed-loop control scheme can be achieved, and high reliability and economical efficiency are achieved.

Description

Technical Field

[0001] This invention relates to the field of DC circuit breakers, and more particularly to a self-excited DC circuit breaker with anti-shoo-through and its economical control method. Background Technology

[0002] Flexible DC grids are a key technology for building new power systems and supporting large-scale integration of renewable energy. Because DC fault currents lack a natural zero-crossing point and have a high rise rate, DC circuit breakers with fast breaking capabilities have become the core protection equipment for flexible DC grids. However, traditional DC circuit breakers require a large number of cascaded power devices to meet high withstand voltage requirements, resulting in high cost and large size. To overcome this drawback, the forced resonant DC circuit breaker has been proposed, which uses a pre-charge capacitor and an LC oscillation circuit to generate a resonant current to transfer and interrupt fault current. This structure significantly reduces the voltage that power electronic devices withstand, resulting in a significant improvement in economic efficiency.

[0003] Forced resonant DC circuit breakers use an excitation source module composed of fully controlled devices (such as IGBTs or reverse-resistance IGCTs) to excite the oscillating current. However, although IGBTs and reverse-resistance IGCTs are fully controlled devices, they both have reverse turn-off times. Reverse-resistance IGCTs, in particular, are prone to dynamic avalanche effects when turning off high-frequency currents, affecting their reliable turn-off. If the turn-on and turn-off timing of the devices is not properly coordinated, a shoot-through phenomenon can easily occur, where all semiconductor devices conduct simultaneously, forming a short-circuit loop, generating a huge short-circuit current, and damaging the equipment. To prevent such shoot-through faults, existing technologies typically set a dead time in the control timing. However, in resonant DC circuit breakers, the presence of a dead time shortens the effective excitation time, reduces the excitation effect of the excitation source on the oscillating current, and thus weakens the circuit breaker's breaking performance.

[0004] Furthermore, current forced resonant DC circuit breakers all employ an outer-loop control strategy for their excitation sources, relying on a pre-set fixed signal to control the conduction and cutoff of power electronic devices. In practical operation, due to the influence of stray parameters, the frequency of the resonant current generated by the LC oscillation module may drift, causing a mismatch between it and the fixed-frequency voltage output by the excitation source. This mismatch severely weakens the excitation effect, limiting further improvements in the circuit breaker's breaking performance. Summary of the Invention

[0005] To address the issues of reduced breaking performance in forced resonant DC circuit breakers with reverse-resistance IGCT or IGBT circuits as the excitation source module, and the mismatch between the resonant current frequency and the excitation source voltage frequency caused by the outer loop control scheme of power electronic devices, this invention proposes an anti-shoo-through self-excited resonant DC circuit breaker and its economical closed-loop control method to solve the above problems.

[0006] This application discloses a self-excited DC circuit breaker with shoot-through protection, including a main branch, a transfer branch, and an energy-dissipating branch. The main branch includes a vacuum switch, and the energy-dissipating branch includes a surge arrester. The transfer branch includes a resonant capacitor, a voltage-controlled power electronic module with shoot-through protection, and a pre-storage capacitor module. The voltage-controlled power electronic module with shoot-through protection includes a first inductor, a second inductor, and a bridge circuit. One end of the first inductor and one end of the second inductor are respectively connected to one arm of the bridge circuit. The other ends of the first inductor and the other ends of the second inductor are connected to the resonant capacitor. The pre-storage capacitor module includes two series capacitors, which are connected in parallel across the bridge circuit. A voltage probe for voltage measurement is connected in parallel with the second inductor. The voltage probe is connected to the bridge circuit through a controller. In the anti-shoo-through voltage-controlled power electronic module, the first inductor, the second inductor, and the resonant capacitor are connected in series to form a resonant module, generating a resonant current. When a power electronic device experiences a shoot-through fault in the bridge circuit, the presence of the first and second inductors suppresses the release of energy from the pre-stored capacitor, ensuring the safety of the power electronic device while stabilizing its duty cycle at the theoretical maximum value. The second inductor provides a voltage signal to achieve closed-loop control of the power electronic device.

[0007] Preferably, the anti-short-through voltage-controlled power electronic module and the pre-storage capacitor module constitute an excitation source module, and the excitation source module is a unidirectional excitation structure or a bidirectional excitation structure.

[0008] Preferably, the first inductor and the second inductor are coupled inductors or ordinary inductors.

[0009] Preferably, the first inductor and the second inductor are ordinary inductors.

[0010] Preferably, the bridge circuit is a full-bridge structure.

[0011] Preferably, the bridge circuit is a half-bridge structure.

[0012] Preferably, the bridge circuit includes a reverse-resistance type IGCT.

[0013] Preferably, the bridge circuit includes an IGBT.

[0014] This application also discloses an economical control method for a shoot-through self-excited resonant DC circuit breaker, implemented based on the aforementioned shoot-through self-excited resonant DC circuit breaker, comprising the following steps: Use a voltage probe to monitor the voltage signal across the inductor module; The monitored voltage signal is filtered and then input into the controller. Determine the zero-crossing point of the resonant current based on the filtered voltage signal; Based on the zero-crossing point, a control signal is generated to adjust the turn-on and turn-off timing of the power electronic devices, so that the output voltage frequency of the excitation source module matches the resonant current frequency.

[0015] Preferably, the method for determining the zero-crossing point of the resonant current includes: The system detects whether the du / dt of the voltage signal is zero, and then detects whether the du / dt reaches a maximum value within tens of microseconds thereafter. If the above conditions are met, it is determined to be the zero-crossing point of the resonant current.

[0016] The beneficial effects of this invention are: (1) A special anti-shoo-through excitation source structure is applied, that is, an inductor module is added between the power electronic module and the LC oscillation module. This can suppress the large current generated when the device shoots through, protect the device from the threat of large current, and make the circuit breaker work more reliably. Under the action of the anti-shoo-through excitation source structure, the drive duty cycle of the power electronic device can approach 50%, which improves the resonant efficiency of the circuit breaker and enhances the breaking performance of the circuit breaker.

[0017] (2) By monitoring the voltage waveform across the added inductor module, the zero-crossing point of the resonant current can be determined, so that the frequency of the resonant current matches the frequency of the excitation source module, thereby improving the resonant efficiency. Moreover, since the inductance value of the added inductor module is small, the measured voltage is the rate of change of voltage at the tap of the inductor module, and the monitored voltage amplitude is small, within 100 volts. This closed-loop control scheme has certain economic advantages. Attached Figure Description

[0018] Figure 1 This is a circuit topology diagram of a self-resonant DC circuit breaker for preventing shoot-through according to an embodiment of the present invention; Figure 2 This is a topology diagram of a DC circuit breaker circuit with bidirectional excitation and coupled inductors, as shown in this embodiment of the invention. Figure 3 This is a schematic diagram of the working state of the transfer branch in a normal operation according to an embodiment of the present invention. Figure 4 A schematic diagram of the waveform of the transfer branch current during normal operation in an embodiment of the present invention; Figure 5 This is a schematic diagram of the working state of the transfer branch when the semiconductors are simultaneously turned on, according to an embodiment of the present invention. Figure 6 This is a schematic diagram of the waveform of the transfer branch current when the semiconductors are simultaneously turned on, according to an embodiment of the present invention. Figure 7 This is a schematic diagram illustrating the process of suppressing short-circuit current in a large inductor in the excitation source when the semiconductors are simultaneously turned on, according to an embodiment of the present invention. Figure 8This is a schematic diagram of the voltage waveform across the inductor module according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the voltage waveform and resonant current waveform of the inductor module after the filter is applied according to an embodiment of the present invention; Figure 10 This is a flowchart of an economical control method for an anti-shot-through self-resonant DC circuit breaker according to an embodiment of the present invention. Figure 11 This is a schematic diagram of the simulation results of an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments.

[0020] One embodiment of this application discloses a DC circuit breaker with anti-shot-through self-resonance, the structure of which is as follows: Figure 1 As shown, the circuit includes a main branch, a transfer branch, and an energy dissipation branch. The main branch includes a vacuum switch, and the energy dissipation branch includes a surge arrester (MOV). The transfer branch includes a resonant capacitor C1, a shoot-through voltage-controlled power electronic module, and a pre-storage capacitor module. The shoot-through voltage-controlled power electronic module includes a first inductor L1, a second inductor L2, and a bridge circuit. One end of the first inductor L1 and one end of the second inductor L2 are respectively connected to one arm of the bridge circuit. The other end of the first inductor L1 and the other end of the second inductor L2 are connected to the resonant capacitor C1. The pre-storage capacitor module includes a first excitation capacitor Cs1 and a second excitation capacitor Cs2 connected in series. The first excitation capacitor Cs1 and the second excitation capacitor Cs2 are connected in series and then connected in parallel across the bridge circuit. A voltage probe for voltage measurement is connected in parallel to the second inductor L2. The voltage probe is connected to the bridge circuit through a controller.

[0021] In the anti-shoo-through voltage-controlled power electronic module, the first and second inductors serve three functions in this topology: First, the first and second inductors, together with the resonant capacitor, form a resonant module, generating a resonant current; second, when a power electronic device experiences a shoot-through fault in the bridge circuit, the presence of the first and second inductors suppresses the release of energy from the pre-stored capacitor, ensuring the safety of the power electronic device while stabilizing its duty cycle at the theoretical maximum value (50%); finally, the second inductor provides a voltage signal to achieve closed-loop control of the power electronic device.

[0022] The anti-shoo-through voltage-controlled power electronics module and the pre-storage capacitor module constitute the excitation source module. The DC circuit breaker excitation source module disclosed in this embodiment is a unidirectional or bidirectional excitation structure. One end of the first inductor L1 and the second inductor L2 constitute the inductor module. The inductor elements in the inductor module are coupled inductors or ordinary inductors, and the bridge circuit is a full-bridge or half-bridge structure. For example, such as... Figure 2As shown, the DC circuit breaker excitation source module is bidirectionally excited. The inductor module includes a first inductor L1 and a second inductor L2 connected in parallel, both of which are coupled inductors. The power electronic device module is a half-bridge structure composed of two semiconductor switching devices T1 and T2 and two diodes D1 and D2. Specifically, the anode of the second switching device T2 is connected to the anode of the first diode D1, forming the left bridge arm, and the cathode of the first switching device T1 is connected to the cathode of the second diode D2, forming the right bridge arm. The left and right bridge arms are connected in parallel, and the cathode of the first diode D1 is connected to the anode of the first switching device T1, and the anode of the second diode D2 is connected to the cathode of the second switching device T2. One end of the first inductor L1 and one end of the second inductor L2 are connected in parallel to the resonant capacitor C1. The other end of the first inductor L1 is connected to the midpoint of the right bridge arm, and the other end of the second inductor L2 is connected to the midpoint of the left bridge arm. In this embodiment, the first excitation capacitor Cs1 and the second excitation capacitor Cs2 of the pre-energy storage capacitor module are connected in parallel across the two ends of the right bridge arm. In this embodiment, the semiconductor device can be either a reverse-resistance IGCT or an IGBT. Figure 2 The reverse-resistance type IGCT is used as an illustration.

[0023] The primary function of the inductor module in this application is to suppress the short-circuit current generated when all power electronic devices are turned on. Under normal operating conditions, capacitor C1 and the inductor module form a resonant module, generating a resonant current. The DC circuit breaker utilizes the square-wave voltage generated by the excitation source module to act on the resonant capacitor C1 in the resonant module, controlling the excitation source voltage conversion frequency to be the same as the frequency of the resonant current, thereby exciting the LC oscillation module, causing the oscillation current to increase until it cancels out the short-circuit current of the main branch. The operating state of the transfer branch in this embodiment is as follows: Figure 3 As shown in (a)-(d), the waveforms of the transferred branch current are as follows: Figure 4 As shown, Izf represents the transfer branch current, Ib represents the main branch current, Imov represents the energy-consuming branch current, and I is only used to indicate the current flow direction in the loop. The specific operating state is as follows: At time t0, T1 is triggered to turn on, and T2 is in the off state. The current path during the t0-t1 period is as follows: Figure 3 As shown in (a); At time t1, the current in T1 crosses zero and T1 receives a turn-off signal. However, since it requires a reverse recovery time, current still flows through it during the period t1-t2. At time t2, T1 is turned off. At this time, both T1 and T2 are off. The current path during the time interval t2-t3 is as follows: Figure 3 As shown in (b); At time t3, T2 triggers conduction. The current path during the time period t3-t4 is as follows: Figure 3 As shown in (c); At time t4, the current at T2 crosses zero and receives a turn-off signal, but because it requires a reverse recovery time, current still flows through it during the period from t4 to t5. At time t5, T2 is turned off. At this time, both T1 and T2 are turned off. The current path during the t5-t6 period is as follows: Figure 3 As shown in (d).

[0024] At time t6, T1 is turned on again, and the loop current path is as follows: Figure 3 As shown in (a), the current path and the output voltage of the excitation source change periodically; At time t7, the amplitude of the current in the transfer branch increases to be equal to that in the main branch. The current in the main branch crosses zero, the arc in the fast vacuum switch is extinguished, and the switching is completed. After that, the system current flows into the transfer branch to charge capacitor C1. At time t8, the voltage across capacitor C1 rises to the MOV operating voltage, and the surge arrester MOV starts to operate, consuming the excess energy stored in the capacitors and inductors in the system.

[0025] When all semiconductors are simultaneously turned on, a large inductor is connected in series in the circuit to suppress short-circuit current. The addition of the anti-shoo-through inductor module allows the duty cycle of the power electronic devices in the excitation source module to approach 50%, improving the breaking performance of the DC circuit breaker. In this embodiment, the process of suppressing the large short-circuit current when all semiconductor devices in the DC circuit breaker's excitation source are simultaneously turned on is as follows: Figure 5 As shown in (a)-(c), the waveforms of the transferred branch current are as follows: Figure 6 As shown. The specific working status is as follows: At time t0, semiconductor device T1 is turned on, and it conducts normally during the t0-t1 period, such as Figure 5 As shown in (a); At time t1, the current in semiconductor device T1 crosses zero, receives a turn-off signal, and begins the reverse recovery process; At time t2, if semiconductor device T1 is operating under standard conditions, it should have completed reverse turn-off and the current should have dropped to 0. However, due to the influence of the working environment, the reverse turn-off time of semiconductor device is increased, and the current in T1 has not yet dropped to 0. At time t3, semiconductor device T2 turns on according to the set timing control. At this time, T1 and T2 turn on simultaneously, creating a short-circuit loop. During the period t3-t4, a very large short-circuit current is expected to be generated, which will damage the devices in the loop. The current path in the loop at this time is as follows: Figure 5 As shown in (b), it can be seen that at this time, a pair of coupled inductors L1 and L2 are connected in series in the circuit, generating mutual inductance, which greatly increases the inductive reactance in the circuit. Under the suppression effect of the large inductive reactance, the rise rate and amplitude of the short-circuit current are suppressed. At time t4, semiconductor device T1 completes reverse turn-off, and the circuit flows normally, such as... Figure 5 As shown in (c); At time t5, the current in semiconductor device T2 crosses zero, receives a turn-off signal, and begins the reverse recovery process; At time t6, if semiconductor device T2 is operating under standard conditions, the reverse recovery process should be completed and the current should drop to 0. However, due to the influence of the working environment, the reverse turn-off time of the semiconductor device is increased, and the current in T2 has not yet dropped to 0. At time t7, semiconductor device T1 is turned on again according to the set timing control. At this time, semiconductor devices T1 and T2 are turned on simultaneously again, and the loop path is as follows. Figure 5 As shown in (b), the coupled inductors L1 and L2 are connected in series to generate a large inductive reactance module, which suppresses the rise of short-circuit current; At time t8, semiconductor device T2 completes reverse turn-off, and the circuit is normally open, as follows: Figure 5 As shown in (a), the current path and the output voltage of the excitation source change periodically; At time t9, the amplitude of the oscillating current rises to be equal to the current in the main branch. The current in the main branch crosses zero, the arc in the fast vacuum switch is extinguished, and the switching is completed. At this time, the system current is transferred to the transfer branch to charge capacitor C1. At time t10, the voltage across C1 rises to the MOV operating voltage of the surge arrester, causing the surge arrester to activate and consume all the excess energy stored in the system.

[0026] Figure 7 The current waveforms of T1 and T2 during the processes t3-t4 and t7-t8 above, i.e., the simultaneous conduction of all reverse-resistance IGCTs in the excitation source, are compared and magnified separately. The dashed line shows the situation when there are no inductors L1 and L2 in the excitation source. Without the suppression effect of the inductors, the short-circuit current rises to a large amplitude in a very short time, which will damage the devices in the circuit. The solid line shows the current waveform when there are inductors L1 and L2 in the excitation source. Under the suppression effect of the large inductor device, the rise rate and amplitude of the short-circuit current are greatly suppressed, and it cannot cause damage to the devices in the circuit.

[0027] As can be seen from the above description, the anti-shot-through topology is feasible and can limit the large current generated when the power electronic devices in the circuit breaker are shot-through. Therefore, the duty cycle of the device drive signal can be adjusted to close to 50%, thereby improving the resonant efficiency of the circuit breaker and enhancing the breaking performance. The following will be a simulation verification of this function.

[0028] Another embodiment of this application discloses an economical control method for a shoot-through self-resonant DC circuit breaker, implemented based on the aforementioned shoot-through self-resonant DC circuit breaker. A second function of the inductor module in this application is to achieve economical closed-loop control of the power electronic devices. The shoot-through voltage-controlled power electronic module, composed of the inductor module, the power electronic device module, the voltage probe, and the controller, forms a closed-loop control system.

[0029] The economical closed-loop control system implementation scheme determines the zero-crossing point of the resonant current by measuring the voltage waveform across a small inductor, and then adjusts the turn-on and turn-off sequence of the power electronic devices. This closed-loop control scheme has two main advantages: 1) It ensures that the frequency of the excitation source voltage and the frequency of the resonant current remain consistent, improving resonant efficiency and enhancing the circuit breaker's breaking performance; 2) Because it measures a small voltage across the inductor, the measurement and monitoring costs are low, resulting in considerable economic benefits. The voltage waveform across the inductor module is shown below. Figure 8 As shown, due to the influence of the loop current, this waveform contains a large number of high-frequency voltage spikes. The waveform after filtering and the resonant current waveform are as follows. Figure 9 As shown in the diagram, it can be seen that at the moment the resonant current crosses zero, the voltage du / dt across the inductor module reaches zero, and then reaches a maximum value within tens of microseconds. Therefore, the zero-crossing point of the resonant current can be found through these two characteristics, and a turn-on / turn-off signal can be sent to the power electronic device. The control logic is as follows: Figure 10 As shown. Includes the following steps: When the DC circuit breaker is operating normally, the voltage frequency generated by the excitation source module does not match the resonant current frequency. The voltage probe monitors the voltage across the inductor module and transmits it to the controller after filtering. The controller analyzes the input voltage waveform and, upon detecting that du / dt = 0 and a maximum value for du / dt within tens of microseconds, sends a control signal to the power electronic device. The power electronic device receives the control signal and switches between on and off states. The voltage frequency generated by the excitation source is adjusted to match the resonant current frequency, improving resonant efficiency and enhancing the circuit breaker's breaking performance.

[0030] By monitoring the voltage across the inductor module, the zero-crossing point of the resonant current can be determined, thereby sending control signals to the power electronic devices and adjusting their conduction timing. This closed-loop control scheme can improve resonant efficiency and is economical.

[0031] In a specific embodiment, the proposed solution is verified through simulation experiments. For the DC circuit breaker proposed in this application, under the same oscillation parameters and pre-stored capacitor, only the drive duty cycle of the power electronic devices is changed, and simulation studies are conducted. Duty cycles of 50% and 40% are selected for comparison, and the simulation results are as follows. Figure 11 As shown.

[0032] The red waveform represents the case with a 50% duty cycle, and the blue waveform represents the case with a 40% duty cycle. The simulation results show: When using a shoot-through topology, the scheme with a 50% device drive duty cycle has higher resonant efficiency. In the interruption region, it can provide 4 zeros for a +15kA fault current and 2 zeros for a -15kA current. In contrast, the scheme with a 40% duty cycle can only provide 2 zeros for a +15kA fault current and cannot provide a zero for a -15kA current.

[0033] Therefore, under the protection of the anti-straight-through topology, the drive duty cycle of the power electronic devices can be safely set at around 50%, thereby improving the resonant efficiency of the circuit breaker and enhancing its breaking performance.

[0034] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A dead-break self-oscillating resonant DC circuit breaker comprising a main branch, a diversion branch and an energy dissipation branch, the main branch comprising a vacuum switch, the energy dissipation branch comprising a surge arrester, characterized in that, The transfer branch comprises a resonance capacitor, a through-prevention voltage-controlled power electronic module and a pre-energy storage capacitor module, the through-prevention voltage-controlled power electronic module comprises a first inductor, a second inductor and a bridge circuit, one end of the first inductor and one end of the second inductor are connected with one bridge arm of the bridge circuit respectively, the other end of the first inductor and the other end of the second inductor are connected and then connected with the resonance capacitor, the pre-energy storage capacitor module comprises two series capacitors, the two series capacitors are connected in parallel as a whole at both ends of the bridge circuit, the second inductor is provided with a voltage probe for voltage measurement, and the voltage probe is connected with the bridge circuit through a controller; The first inductor and the second inductor in the through-prevention voltage-controlled power electronic module are connected in series with the resonance capacitor to form a resonance module, and a resonance current is generated; when a power electronic device in the bridge circuit is in a through fault, the pre-energy storage capacitor energy release is inhibited due to the existence of the first inductor and the second inductor, so as to ensure the safety of the power electronic device and make the conduction duty cycle of the power electronic device stable at the maximum theoretical duty cycle; The second inductor provides a voltage signal to realize closed-loop control of the power electronic device.

2. The anti-pumping self-resonating DC circuit breaker according to claim 1, characterized in that, The through-prevention voltage-controlled power electronic module and the pre-energy storage capacitor module constitute an excitation source module, and the excitation source module is a one-way excitation structure or a two-way excitation structure.

3. The anti-pumping self-resonating DC circuit breaker according to claim 1, characterized in that, The first inductor and the second inductor are coupled inductors or ordinary inductors.

4. The anti-pumping self-resonating DC circuit breaker according to claim 1, characterized in that, The first inductor and the second inductor are ordinary inductors.

5. The anti-pumping self-resonating DC circuit breaker according to claim 1, characterized in that, The bridge circuit is a full-bridge structure.

6. The anti-pumping self-resonating DC circuit breaker of claim 1, wherein, The bridge circuit is a half-bridge structure.

7. The anti-pumping self-resonating DC circuit breaker according to claim 5 or 6, characterized in that, The bridge circuit comprises an inverse blocking IGCT.

8. The anti-pumping self-resonating DC circuit breaker according to claim 5 or 6, characterized in that, The bridge circuit comprises an IGBT.

9. An economical control method of a dead-break self-excited resonant DC circuit breaker, characterized by, The through-prevention self-excitation resonance DC circuit breaker according to any one of claims 1-8 comprises the following steps: A voltage probe is used to monitor the voltage signal at both ends of the inductor module; The monitored voltage signal is input into a controller after being filtered; The zero-crossing point of the resonance current is determined according to the filtered voltage signal; A control signal is generated according to the zero-crossing point, and the turn-on and turn-off timing of the power electronic device is adjusted, so that the frequency of the excitation source module output voltage matches the frequency of the resonance current.

10. The economic control method of the anti- through self- resonant DC circuit breaker according to claim 9, characterized in that, The method for determining the zero-crossing point of the resonance current comprises: Detecting whether du / dt of the voltage signal is zero, and detecting whether du / dt appears a maximum value within tens of microseconds after that; If the above conditions are met, it is determined that the resonance current is at the zero-crossing point.

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