Direct-current circuit breaker with rapid current suppression capability and working method of direct-current circuit breaker

Abstract

The invention relates to the technical field of direct-current circuit breaker manufacturing, in particular to a direct-current circuit breaker with a rapid current suppression capability and a working method of the direct-current circuit breaker. The main branch is a line from the L side to the R side and sequentially passes through a secondary side winding N2 of the coupling inductor and a pair of anti-parallel thyristors. Each of the four charging branches comprises a diode and is matched with a resistor of the charging resistor branch to provide a charging loop for two capacitors in the two capacitor branches, and two buffer branches are respectively connected in parallel with the two capacitor branches. After a thyristor of the trigger branch is triggered, a capacitor of the capacitor branch can transmit energy to N2 in the main branch through a primary side winding N1 of a coupling inductor in the energy transfer branch, and then bidirectional current is cut off. The direct-current circuit breaker is designed by using the coupling inductor and the thyristor, and the direct-current circuit breaker has the advantages of high efficiency, rapid current suppression, good controllability, reprotection after reclosing, low cost and high reliability in the current breaking process.

Description

Technical Field

[0001] The present invention belongs to the field of direct current circuit breaker manufacturing, and in particular relates to a direct current circuit breaker with rapid current suppression capability and a working method thereof. Background Art

[0002] For DC power systems, such as energy storage devices, photovoltaic power generation, wind power generation, and electric vehicle charging stations, system protection is crucial. Unlike AC systems, the short-circuit current in DC systems rises faster and has a larger amplitude, which seriously threatens DC systems and related equipment. DC circuit breakers can quickly and accurately detect and interrupt fault currents, thereby preventing the spread of faults and protecting equipment, ultimately improving the stability and reliability of the system. Therefore, they have become key equipment for DC protection, which is also an important direction of in-depth research in the field of power engineering in recent years.

[0003] Solid-state DC circuit breakers are designed based on solid-state switching devices. Compared with traditional mechanical circuit breaker solutions, they have the characteristics of fast current interruption, so they have been widely studied. Compared with fully controlled switches, semi-controlled devices thyristors have advantages such as low on-resistance, mature manufacturing process, low purchase price, and large surge current capacity. In recent years, a number of DC circuit breaker topology designs based on thyristors have emerged. However, the existing thyristor-based solid-state DC circuit breakers still have the following problems: (1) Passive thyristor-type solid-state DC circuit breakers can only operate after a fault occurs, so they cannot interrupt the current during normal system operation, resulting in poor controllability. (2) When the load changes, the line current will fluctuate, and its characteristics are similar to those of the fault condition. Therefore, the passive solution may be triggered by mistake, resulting in the system being shut down by mistake. (3) During the current interruption process, the external line current still rises, so the power electronic devices in the DC system will be subjected to higher current stress. (4) The operating current passes through multiple power electronic devices in the main branch, and the on-resistance is large, resulting in low efficiency. (5) After the current is interrupted for the first time, the circuit breaker is usually reclosed to determine whether the fault still exists. Some existing solutions cannot provide reclosing protection, which limits the application scenarios. (6) The thyristor turn-off circuit contains external parameters, and the reliability of the current interruption process is low. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a DC circuit breaker with rapid current suppression capability and a working method thereof, which solves the common problems of the existing thyristor-type solid-state DC circuit breakers, such as poor controllability, easy false triggering, line current still rising after operation, low efficiency, lack of reclosing protection and low reliability of the current interruption process.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A DC circuit breaker with fast current suppression capability comprises an energy dissipation branch, a main branch, a charging branch, a capacitor branch, a buffer branch, a trigger branch, a charging resistor branch and an energy transfer branch; One side of the main branch is the L side, and the other side is the R side. From the L side to the R side, it passes through the a2 end and the b2 end of the secondary winding N2 of the coupled inductor, and a pair of reverse parallel thyristors T m1 and T m2 The b2 end of the winding N2 and the thyristor T m1 Anode and thyristor T m2 cathode connection, while the thyristor T m1 The cathode and T m2 The anode is connected to the R side of the main line; The energy dissipation branch includes a lightning arrester MOV, which is connected in parallel to the main branch; The charging branch includes a first charging branch, a second charging branch, a third charging branch and a fourth charging branch; the first charging branch includes a diode D1, the second charging branch includes a diode D2, the third charging branch includes a diode D3, and the fourth charging branch includes a diode D4; The capacitor branch includes a first capacitor branch and a second capacitor branch; the first capacitor branch includes a capacitor C 1. The second capacitor branch includes capacitor C 2; The charging resistance branch includes a resistor R g ; The anode of diode D1 is connected to the main branch L side, and the cathode is connected to the capacitor C 1 one end; capacitor C The other end of 1 is connected to the anode of diode D3, and the cathode of diode D3 is connected to the resistor R g One end, and the resistor R g The other end is grounded; during normal operation, the capacitor C 1. The circuit from the main branch L side through the first charging branch, the first capacitor branch, the third charging branch and the charging resistor branch to the ground is charged to the system voltage; The anode of diode D2 is connected to the main branch R side, and the cathode is connected to the capacitor C 2 one end; capacitor C 2The other end is connected to the anode of diode D4, and the cathode of diode D4 is connected to the resistor R g One end; During normal operation, the capacitor C 2. The circuit from the main branch R side through the second charging branch, the second capacitor branch, the fourth charging branch and the charging resistor branch to the ground is charged to the system voltage; The energy transfer branch includes a primary winding N1 of a coupled inductor; the trigger branch includes a first trigger branch and a second trigger branch, the first trigger branch includes a thyristor T C1 The second trigger branch includes thyristor T C2 ; The a1 end of winding N1 is connected to the cathode of diode D1 and thyristor T C2 Anode of thyristor T C2 The cathode of winding N1 is connected to the anode of diode D4; the b1 end of winding N1 is connected to the cathode of diode D2 and thyristor T C1 Anode of thyristor T C1 The cathode of is connected to the anode of diode D3; And the a1 end of the winding N1 and the a2 end of the winding N2 are the same end, and the b1 end of the winding N1 and the b2 end of the winding N2 are the same end; The buffer branch includes a first buffer branch and a second buffer branch; The first buffer branch is connected in parallel with the capacitor C 1, which includes a diode D C1 and arrester M C1 ; diode D C1 The cathode is connected to the cathode of diode D1. C1 Anode connected to arrester M C1 One end, arrester M C1 The other end is connected to the anode of diode D3; The second buffer branch is connected in parallel with the capacitor C 2, which includes a diode D C2 and arrester M C2 , diode D C2 The cathode is connected to the cathode of diode D2. C2 Anode connected to arrester M C2 One end, arrester M C2 The other end is connected to the anode of diode D4.

[0006] A method for operating a DC circuit breaker with rapid current suppression capability comprises the following steps: S1, waiting for the capacitance of the first capacitance branch C 1 From the main branch L side through the first charging branch, the first capacitor branch, the third charging branch and the charging resistor branch to the ground circuit to charge to the system voltage; at the same time, wait for the capacitor of the second capacitor branch C 2. The circuit from the main branch R side through the second charging branch, the second capacitor branch, the fourth charging branch and the charging resistor branch to the ground is charged to the system voltage and enters S2; S2, determine whether the system has started to start, if so, enter S3, otherwise return to S1; S3, trigger the thyristor T of the main branch at the same time m1 and T m2 , and enter S4; S4, determine whether the main branch current reverses and crosses zero when the system is running. If so, enter S3, otherwise enter S5; S5, determine whether the current disconnection signal is received, if so, enter S6, otherwise enter S4; S6, determine whether the main branch current flows from the L side to the R side, if so, go to S7, otherwise go to S8; S7, turn on the first trigger branch and the main branch thyristor T m1 and T m2 ,capacitance C 1 Energy is transferred from winding N1 to winding N2 through the coupled inductor. The energy dissipation branch successfully clamps the voltage, and the external line current is quickly suppressed. At the same time, the main branch current drops to zero and flows in the reverse direction through T m2 , T m1 Successfully shut down; then the capacitor C 1 continues to resonate through winding N1, and then the polarity changes and energy is discharged through the first buffer branch. Finally, the thyristor T C1 Withstand the capacitor reverse voltage and shut down; and enter S9; S8, turn on the second trigger branch and the main branch thyristor T m1 and T m2 ,capacitance C 2 Energy is transferred from winding N1 to winding N2 through the coupled inductor. The energy dissipation branch successfully clamps the voltage, and the external line current is quickly suppressed. At the same time, the main branch current drops to zero and flows in the reverse direction through T m1 , T m2 Successfully shut down; then the capacitor C 2 continues to resonate through winding N1, and then the polarity changes and energy is discharged through the second buffer branch. Finally, the thyristor T C2 Withstand the capacitor reverse voltage and shut down; and enter S9; S9: Determine whether reclosing is required. If yes, go to S1, otherwise end.

[0007] The beneficial effects of the present invention are: (1) The DC circuit breaker of the present invention uses cheap semi-controlled devices, such as thyristors, to design the DC circuit breaker, which is lower in cost than the solution based on a fully controlled switch. Both capacitors draw power from the main branch through the charging branch and the charging resistor branch, so no additional charging power source is required. This solution can reduce both cost and operation difficulty.

[0008] (2) After a fault occurs in the DC circuit breaker of the present invention, due to the unidirectional flow of the diode in the first to fourth branch, the capacitor C 1 and C2 Energy cannot be discharged through the fault point, so the capacitor voltage remains unchanged, thereby improving the breaking reliability.

[0009] (3) The current of the DC circuit breaker of the present invention only passes through a single thyristor and winding N2 when the system is running, with low on-resistance and high efficiency; if a fault occurs on the R side, the capacitor C 1 The charging circuit is not affected; if a fault occurs on the L side, the capacitor C 2 The charging circuit is not affected. After the current is interrupted, the capacitor returns to its initial state, which can provide conditions for reclosing protection.

[0010] (4) The working method of the present invention is different from the passive scheme that uses the fault itself as the trigger condition. It adopts active control and can actively disconnect the operating current, so the controllability is good; and when the load is switched and the system current fluctuates, it will not be triggered by mistake.

[0011] (5) The working method of the present invention utilizes coupling inductance and charging capacitor. After successful operation, the arrester in the energy dissipation branch operates to clamp the voltage across the circuit breaker to a level higher than the system voltage, thereby quickly suppressing the line current and effectively protecting the DC system.

[0012] (6) The working method of the present invention adopts the same control method when interrupting the operating current or the fault current, that is, turning on the thyristor in the trigger branch, and the control steps are simple; and the turn-off process of the thyristor in the main branch is independent of the external circuit, so the current interruption reliability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A circuit diagram of a DC circuit breaker with rapid current suppression capability proposed by the present invention.

[0014] Figure 2 This is a flow chart of a working method of a DC circuit breaker with rapid current suppression capability proposed by the present invention. DETAILED DESCRIPTION

[0015] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0016] like Figure 1 As shown, the DC circuit breaker based on thyristors and transformers of the present invention includes: an energy dissipation branch, a main branch, first to fourth charging branches, first and second capacitor branches, first and second buffer branches, first and second trigger branches, a charging resistor branch and an energy transfer branch.

[0017] One side of the main branch is the L side, and the other side is the R side. From the L side to the R side, it passes through the secondary winding N2 of the transformer (end a2 to end b2) and a pair of reverse parallel thyristors T m1 and T m2The b2 end of the winding N2 is connected to the thyristor T m1 Anode and thyristor T m2 cathode connection, while the thyristor T m1 The cathode and T m2 The anode of the capacitor is connected to the main line R side. The energy dissipation branch contains a lightning arrester MOV, which is connected in parallel with the main branch.

[0018] The first charging branch includes a diode D1, the anode of the diode D1 is connected to the L side of the main branch, and the cathode of the diode D1 is connected to the capacitor in the first capacitor branch. C 1 one end. Capacitor C The other end is connected to the anode of the diode D3 in the third charging branch, and the cathode of the diode D3 is connected to the resistor in the charging resistor branch. R g One end, and the resistor R g The other end is grounded. In normal operation, the capacitor C 1 can be charged to the system voltage from the main branch L side through the first charging branch, the first capacitor branch, the third charging branch, the charging resistor branch to the ground.

[0019] The second charging branch includes a diode D2, the anode of the diode D2 is connected to the R side of the main branch, and the cathode of the diode D2 is connected to the capacitor in the second capacitor branch. C 2. One end. Capacitor C 2 is connected to the anode of the diode D4 in the fourth charging branch, and the cathode of the diode D4 is connected to the resistor in the charging resistor branch. R g One end, and the resistor R g The other end is grounded. In normal operation, the capacitor C 2 can be charged to the system voltage from the main branch R side through the second charging branch, the second capacitor branch, the fourth charging branch, the charging resistor branch to the ground circuit.

[0020] The energy transfer branch includes a primary winding N1 of a coupled inductor. The a1 end of the winding N1 is connected to the cathode of the diode D1 in the first charging branch and the thyristor T in the second triggering branch. C2 anode of the thyristor T C2 The cathode of the winding N1 is connected to the anode of the diode D4 in the fourth charging branch. In addition, the end b1 of the winding N1 is connected to the cathode of the diode D2 in the second charging branch and the thyristor T in the first triggering branch. C1 anode of the thyristor T C1 The cathode of the winding N1 is connected to the anode of the diode D3 in the third charging branch. It should be noted that the a1 end of the winding N1 and the a2 end of the winding N2 are the same end, and the b1 end of the winding N1 and the b2 end of the winding N2 are the same end.

[0021] The first buffer branch comprises a diode D C1 and arrester M C1 , diode D C1 The cathode is connected to the cathode of the diode D1 in the first charging branch, and the diode D C1 Anode connected to arrester M C1 , lightning arrester M C1 The other end is connected to the anode of diode D3. Overall, the first buffer branch is connected in parallel with the capacitor C 1. The second buffer branch includes a diode D C2 and arrester M C2 , diode D C2 The cathode is connected to the cathode of the diode D2 in the second charging branch, and the diode D C2 Anode connected to arrester M C2 , lightning arrester M C2 The other end is connected to the anode of diode D4. Overall, the second buffer branch is connected in parallel with the capacitor C 2.

[0022] The present invention is used in DC systems such as energy storage equipment, photovoltaic power generation, wind power generation and electric vehicle charging stations, and can effectively protect the DC systems.

[0023] like Figure 2 As shown, a working method of a DC circuit breaker with fast current suppression capability comprises the following steps: S1, waiting for the capacitance of the first capacitance branch C 1 From the main branch L side, through the first charging branch, the first capacitor branch, the third charging branch, the charging resistor branch to the ground, the circuit is charged to the system voltage. At the same time, wait for the capacitor of the second capacitor branch to C 2. The circuit from the main branch R side is charged to the system voltage through the second charging branch, the second capacitor branch, the fourth charging branch, the charging resistor branch to the ground. And enters S2; S2, determine whether the system has started to start, if so, enter S3, otherwise return to S1; S3, trigger the main branch thyristor T at the same time m1 and T m2 , and enter S4; S4, determine whether the main branch current reverses and crosses zero when the system is running. If so, enter S3, otherwise enter S5; S5, determine whether the current disconnection signal is received, if so, enter S6, otherwise enter S4; S6, determine whether the main branch current flows from the L side to the R side, if so, go to S7, otherwise go to S8; S7, turn on the first trigger branch and the main branch thyristor Tm1 and T m2 ,capacitance C 1 Energy is transferred from the coupling inductor N1 to N2, the energy dissipation branch successfully clamps the voltage, the external line current is quickly suppressed, and the main branch current drops to zero and flows in the reverse direction through T m2 , T m1 Successfully shut down. Then the capacitor C 1 continues to resonate through winding N1, and then the polarity changes and energy is discharged through the first buffer branch. Finally, the thyristor T C1 The capacitor is shut down when it is subjected to reverse voltage. And enter S9; S8, turn on the second trigger branch and the main branch thyristor T m1 and T m2 ,capacitance C 2 Energy is transferred from the coupling inductor N1 to N2, and the energy dissipation branch successfully clamps the voltage. The external line current is quickly suppressed, and the main branch current drops to zero and flows through T in the reverse direction. m1 , T m2 Successfully shut down. Then the capacitor C 2 continues to resonate through winding N1, and then the polarity changes and energy is discharged through the second buffer branch. Finally, the thyristor T C2 The capacitor is shut down when it is subjected to reverse voltage. And enter S9; S9: Determine whether reclosing is required. If yes, go to S1, otherwise end.

[0024] In this example, it is necessary to ensure that the thyristor T m1 , T m2 , T C1 and T C2 The reverse recovery process is long enough to be shut down reliably.

[0025] In this example, the external inductor design needs to be considered to ensure that the system current is not negative.

[0026] In this example, the design of the coupled inductor needs to be considered to avoid generating large stress inside the circuit breaker.

[0027] In this example, the current requirements of each device need to be considered to avoid inrush current from damaging the device.

Claims

1. A DC circuit breaker with fast current suppression capability, characterized in that: It includes an energy dissipation branch, a main branch, a charging branch, a capacitor branch, a buffer branch, a trigger branch, a charging resistor branch and an energy transfer branch; One side of the main branch is the L side, and the other side is the R side. From the L side to the R side, it passes through the a2 end and the b2 end of the secondary winding N2 of the coupled inductor, and a pair of reverse parallel thyristors T m1 and T m2 The b2 end of the winding N2 and the thyristor T m1 Anode and thyristor T m2 cathode connection, while the thyristor T m1 The cathode and T m2 The anode is connected to the R side of the main line; The energy dissipation branch includes a lightning arrester MOV, which is connected in parallel to the main branch; The charging branch includes a first charging branch, a second charging branch, a third charging branch and a fourth charging branch; the first charging branch includes a diode D1, the second charging branch includes a diode D2, the third charging branch includes a diode D3, and the fourth charging branch includes a diode D4; The capacitor branch includes a first capacitor branch and a second capacitor branch; the first capacitor branch includes a capacitor C 1. The second capacitor branch includes capacitor C 2; The charging resistance branch includes a resistor R g ; The anode of diode D1 is connected to the main branch L side, and the cathode is connected to the capacitor C 1 one end; capacitor C The other end of 1 is connected to the anode of diode D3, and the cathode of diode D3 is connected to the resistor R g One end, and the resistor R g The other end is grounded; during normal operation, the capacitor C 1. The circuit from the main branch L side through the first charging branch, the first capacitor branch, the third charging branch and the charging resistor branch to the ground is charged to the system voltage; The anode of diode D2 is connected to the main branch R side, and the cathode is connected to the capacitor C 2 one end; capacitor C 2The other end is connected to the anode of diode D4, and the cathode of diode D4 is connected to the resistor R g One end; During normal operation, the capacitor C 2. The circuit from the main branch R side through the second charging branch, the second capacitor branch, the fourth charging branch and the charging resistor branch to the ground is charged to the system voltage; The energy transfer branch includes a primary winding N1 of a coupled inductor; the trigger branch includes a first trigger branch and a second trigger branch, the first trigger branch includes a thyristor T C1 The second trigger branch includes thyristor T C2 ; The a1 end of winding N1 is connected to the cathode of diode D1 and thyristor T C2 Anode of thyristor T C2 The cathode of winding N1 is connected to the anode of diode D4; the b1 end of winding N1 is connected to the cathode of diode D2 and thyristor T C1 Anode of thyristor T C1 The cathode of is connected to the anode of diode D3; And the a1 end of the winding N1 and the a2 end of the winding N2 are the same end, and the b1 end of the winding N1 and the b2 end of the winding N2 are the same end; The buffer branch includes a first buffer branch and a second buffer branch; The first buffer branch is connected in parallel with the capacitor C 1, which includes a diode D C1 and arrester M C1 ; diode D C1 The cathode is connected to the cathode of diode D1. C1 Anode connected to arrester M C1 One end, arrester M C1 The other end is connected to the anode of diode D3; The second buffer branch is connected in parallel with the capacitor C 2, which includes a diode D C2 and arrester M C2 , diode D C2 The cathode is connected to the cathode of diode D2. C2 Anode connected to arrester M C2 One end, arrester M C2 The other end is connected to the anode of diode D4.

2. A method for operating a DC circuit breaker with fast current suppression capability as claimed in claim 1, characterized in that: The following steps are involved: S1, waiting for the capacitance of the first capacitance branch C 1 From the main branch L side through the first charging branch, the first capacitor branch, the third charging branch and the charging resistor branch to the ground circuit to charge to the system voltage; at the same time, wait for the capacitor of the second capacitor branch C 2. The circuit from the main branch R side through the second charging branch, the second capacitor branch, the fourth charging branch and the charging resistor branch to the ground is charged to the system voltage and enters S2; S2, determine whether the system has started to start, if so, enter S3, otherwise return to S1; S3, trigger the thyristor T of the main branch at the same time m1 and T m2 , and enter S4; S4, determine whether the main branch current reverses and crosses zero when the system is running. If so, enter S3, otherwise enter S5; S5, determine whether the current disconnection signal is received, if so, enter S6, otherwise enter S4; S6, determine whether the main branch current flows from the L side to the R side, if so, go to S7, otherwise go to S8; S7, turn on the first trigger branch and the main branch thyristor T m1 and T m2 ,capacitance C 1 Energy is transferred from winding N1 to winding N2 through the coupled inductor. The energy dissipation branch successfully clamps the voltage, and the external line current is quickly suppressed. At the same time, the main branch current drops to zero and flows in the reverse direction through T m2 , T m1 Successfully shut down; then the capacitor C 1 continues to resonate through winding N1, and then the polarity changes and energy is discharged through the first buffer branch. Finally, the thyristor T C1 Withstand capacitor reverse voltage and shut down; And enter S9; S8, turn on the second trigger branch and the main branch thyristor T m1 and T m2 ,capacitance C 2 Energy is transferred from winding N1 to winding N2 through the coupled inductor. The energy dissipation branch successfully clamps the voltage, and the external line current is quickly suppressed. At the same time, the main branch current drops to zero and flows in the reverse direction through T m1 , T m2 Successfully shut down; then the capacitor C 2 continues to resonate through winding N1, and then the polarity changes and energy is discharged through the second buffer branch. Finally, the thyristor T C2 Withstand capacitor reverse voltage and shut down; And enter S9; S9: Determine whether reclosing is required. If yes, go to S1, otherwise end.

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