A redundant trigger circuit for bypass switch of flexible DC converter valve

Abstract

The present invention discloses a redundant trigger circuit for a bypass switch of a flexible direct current converter valve, comprising a first charging resistor, a second charging resistor, a first energy storage capacitor, a second energy storage capacitor, a first thyristor, a second thyristor, a first thyristor trigger circuit, a second thyristor trigger circuit, a first diode, a second diode, a third diode, a fourth diode, a bypass switch trigger coil, a second voltage detection circuit and a first voltage detection circuit, wherein the positive electrodes of the first charging resistor and the second charging resistor are connected in parallel to the positive electrode of the power supply, the negative electrode of the first charging resistor is connected to the first energy storage capacitor and the first voltage detection circuit connected in parallel, the negative electrode of the first charging resistor is connected to the anode of the second thyristor, and the gate of the second thyristor is connected to the second thyristor trigger circuit. The beneficial effect of the present invention is that the charging current of the energy storage capacitor is set to flow through the bypass switch trigger coil, so as to detect the on-off state of the bypass switch trigger coil.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a redundant trigger circuit for a bypass switch of a flexible direct current converter valve. Background Art

[0002] The main circuit structure of the bridge arm of the MMC flexible DC transmission converter valve is composed of multiple power units in series. When a single power unit fails, a reliable bypass is required to ensure the continued operation of the equipment. The current traditional practice is to configure only a set of charging resistors, a capacitor, and a thyristor in series with the trigger coil of the bypass switch. When the thyristor is triggered to turn on, the capacitor discharges to the trigger coil of the bypass switch, triggering the bypass switch to close. The traditional bypass switch trigger circuit cannot detect the on and off state of the bypass switch trigger coil. When the bypass switch trigger coil has an open circuit fault, it will cause the bypass switch to refuse to operate, which will cause the entire equipment to trip and stop operating. The reliability needs to be improved. Summary of the invention

[0003] In view of the above problems, the present invention proposes a redundant trigger circuit for a bypass switch of a flexible DC converter valve, which mainly solves the problems of the background technology, detects the on-off state of the bypass switch trigger coil, and realizes a redundant trigger function.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A redundant trigger circuit for a bypass switch of a flexible direct current converter valve comprises a first charging resistor, a second charging resistor, a first energy storage capacitor, a second energy storage capacitor, a first thyristor, a second thyristor, a first thyristor trigger circuit, a second thyristor trigger circuit, a first diode, a second diode, a third diode, a fourth diode, a bypass switch trigger coil, a second voltage detection circuit and a first voltage detection circuit, wherein the positive electrodes of the first charging resistor and the second charging resistor are connected in parallel to the positive electrode of a power supply, the negative electrode of the first charging resistor is connected to the first energy storage capacitor and the first voltage detection circuit connected in parallel, the negative electrode of the first charging resistor is connected to the anode of the second thyristor, the gate of the second thyristor is connected to one end of the second thyristor trigger circuit, the cathode of the second thyristor is connected to the other end of the second thyristor trigger circuit and the second diode The anode of the first energy storage capacitor is connected to the cathode of the third diode. Similarly, the negative electrode of the second charging resistor is connected to the second energy storage capacitor connected in parallel and the second voltage detection circuit. The negative electrode of the second charging resistor is connected to the anode of the first thyristor. The gate of the first thyristor is connected to one end of the first thyristor trigger circuit. The cathode of the first thyristor is connected to the other end of the first thyristor trigger circuit and the anode of the first diode. The negative electrode of the second energy storage capacitor is connected to the cathode of the fourth diode. The anode of the first diode is connected to the cathode of the third diode. The anode of the second diode is connected to the cathode of the fourth diode. The cathodes of the first diode and the second diode are connected to one end of the bypass switch trigger coil. The other end of the bypass switch trigger coil is connected in parallel with the anodes of the third diode and the fourth diode and connected to the negative electrode of the power supply.

[0006] The beneficial effects of the present invention are:

[0007] 1. A redundant trigger circuit for a bypass switch of a flexible DC converter valve designed in the present invention realizes the function of detecting the on-off state of the bypass switch trigger coil by setting the charging current of the energy storage capacitor to flow through the bypass switch trigger coil.

[0008] 2. The present invention uses only a single power supply, has low requirements for engineering power supply, and adopts a redundant bypass switch trigger circuit, which has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A schematic diagram of a redundant trigger circuit for a bypass switch of a flexible direct current converter valve according to an embodiment of the present invention;

[0010] Figure 2 This is a schematic diagram of a thyristor trigger circuit in a schematic diagram of a redundant trigger circuit for a bypass switch of a flexible DC converter valve according to an embodiment of the present invention;

[0011] Figure 3 This is a schematic diagram of a voltage detection circuit in a schematic diagram of a redundant trigger circuit for a bypass switch of a flexible DC converter valve according to an embodiment of the present invention.

[0012] Among them: 1. first charging resistor; 2. second charging resistor; 3. first energy storage capacitor; 4. second energy storage capacitor; 5. first thyristor; 6. second thyristor; 7. first thyristor trigger circuit; 8. second thyristor trigger circuit; 9. first diode; 10. second diode; 11. third diode; 12. fourth diode; 13. bypass switch trigger coil; 14. second voltage detection circuit; 15. first voltage detection circuit; 16. isolation transformer; 17. rectifier diode; 18. current limiting resistor; 19. anti-parallel diode; 20. upper sampling resistor; 21. lower sampling resistor; 22. hysteresis comparator. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the content of the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all the contents.

[0014] according to Figure 1As shown, this embodiment proposes a redundant trigger circuit for a bypass switch of a flexible direct current converter valve, comprising a first charging resistor 1, a second charging resistor 2, a first energy storage capacitor 3, a second energy storage capacitor 4, a first thyristor 5, a second thyristor 6, a first thyristor trigger circuit 7, a second thyristor trigger circuit 8, a first diode 9, a second diode 10, a third diode 11, a fourth diode 12, a bypass switch trigger coil 13, a second voltage detection circuit 14 and a first voltage detection circuit 15, wherein the positive electrodes of the first charging resistor 1 and the second charging resistor 2 are connected in parallel to the positive electrode of the power supply, the negative electrode of the first charging resistor 1 is connected to the first energy storage capacitor 3 and the first voltage detection circuit 15 connected in parallel, the negative electrode of the first charging resistor 1 is connected to the anode of the second thyristor 6, the gate of the second thyristor 6 is connected to one end of the second thyristor trigger circuit 8, the cathode of the second thyristor 6 is connected to the other end of the second thyristor trigger circuit 8 and the first The anode of the second diode 10 is connected, the negative electrode of the first energy storage capacitor 3 is connected to the cathode of the third diode 11. Similarly, the negative electrode of the second charging resistor 2 is connected to the second energy storage capacitor 4 connected in parallel and the second voltage detection circuit 14, the negative electrode of the second charging resistor 2 is connected to the anode of the first thyristor 5, the gate of the first thyristor 5 is connected to one end of the first thyristor trigger circuit 7, the cathode of the first thyristor 5 is connected to the other end of the first thyristor trigger circuit 7 and the anode of the first diode 9, the negative electrode of the second energy storage capacitor 4 is connected to the cathode of the fourth diode 12, the anode of the first diode 9 is connected to the cathode of the third diode 11, the anode of the second diode 10 is connected to the cathode of the fourth diode 12, the cathodes of the first diode 9 and the second diode 10 are connected to one end of the bypass switch trigger coil 13, and the other end of the bypass switch trigger coil 13 is connected in parallel with the anodes of the third diode 11 and the fourth diode 12 to the negative electrode of the power supply.

[0015] The first thyristor trigger circuit 7 and the second thyristor trigger circuit 8 both include an isolation transformer 16, a rectifier diode 17, a current limiting resistor 18 and an anti-parallel diode 19. The power transformer 16 receives a trigger signal, and one end of its output side drives the first thyristor 5 or the second thyristor 6 through the rectifier diode 17 and the current limiting resistor 18. The anode of the anti-parallel diode 19 is connected to the other end of the output side, and the cathode of the anti-parallel diode 19 is connected to the current limiting resistor 18.

[0016] The second voltage detection circuit 14 and the first voltage detection circuit 15 both include an upper sampling resistor 20, a lower sampling resistor 21 and a hysteresis comparator 22. The upper sampling resistor 20 and the lower sampling resistor 21 are connected in series and then connected in parallel at both ends of the first energy storage capacitor 3 or the second energy storage capacitor 4. The connection point between the upper sampling resistor 20 and the lower sampling resistor 21 is connected to the input end of the hysteresis comparator 22. The output end of the hysteresis comparator 22 is the output end of the voltage detection circuit.

[0017] Here’s how it works:

[0018] The positive electrode of the power supply charges the first energy storage capacitor 3 through the first charging resistor 1, and the first energy storage capacitor 3 will gradually charge to a voltage close to the power supply; the power supply charges the second energy storage capacitor 4 through the second charging resistor 2, and the second energy storage capacitor 4 will gradually charge to a voltage close to the power supply.

[0019] The charging path of the first energy storage capacitor 3 is: the positive electrode of the power supply via the first charging resistor 1, the first energy storage capacitor 3, the first diode 9, the bypass switch trigger coil 13, and the negative electrode of the power supply.

[0020] The charging path of the second energy storage capacitor 4 is: the positive electrode of the power supply via the second charging resistor 2, the second energy storage capacitor 4, the second diode 10, the bypass switch trigger coil 13, and the negative electrode of the power supply.

[0021] The discharge path of the first energy storage capacitor 3 is: the upper end of the first energy storage capacitor 3 , the second thyristor 6 , the second diode 10 , the bypass switch trigger coil 13 , the third diode 11 , and the negative electrode of the first energy storage capacitor 3 .

[0022] The discharge path of the second energy storage capacitor 4 is: the upper end of the second energy storage capacitor 4 , the first thyristor 5 , the first diode 9 , the bypass switch trigger coil 13 , the fourth diode 12 , and the negative electrode of the second energy storage capacitor 4 .

[0023] The first energy storage capacitor 3 is connected in parallel with a first voltage detection circuit 15 , which can detect the charging voltage state of the first energy storage capacitor 3 .

[0024] The second energy storage capacitor 4 is connected in parallel with a second voltage detection circuit 14 , which can detect the charging voltage state of the second energy storage capacitor 4 .

[0025] When the bypass switch trigger coil 13 in the circuit is in the on state, the redundant trigger circuit for the bypass switch of the flexible DC converter valve in this embodiment works as follows:

[0026] 1) Before a redundant trigger circuit for a bypass switch of a flexible direct current converter valve is started, the voltage of the first energy storage capacitor 3 and the second energy storage capacitor 4 is 0V, the first thyristor trigger circuit 7 and the second thyristor trigger circuit 8 have no trigger signal, and the first thyristor 5 and the second thyristor 6 are in a cut-off state;

[0027] 2) After the power supply is powered on, the power supply charges the first energy storage capacitor 3 via the first charging resistor 1, the first energy storage capacitor 3, the first diode 9, and the bypass switch trigger coil 13; the power supply charges the second energy storage capacitor 4 via the second charging resistor 2, the second energy storage capacitor 4, the second diode 10, and the bypass switch trigger coil 13.

[0028] 3) Since the first thyristor 5 and the second thyristor 6 are both in the cut-off state, no current flows, so that the voltage of the first energy storage capacitor 3 and the second energy storage capacitor 4 is continuously charged to a voltage close to the power supply voltage. The charging state of the first energy storage capacitor 3 and the second energy storage capacitor 4 can be identified through the first voltage detection circuit 15 and the second voltage detection circuit 14.

[0029] 4) When the first thyristor trigger circuit 7 or the second thyristor trigger circuit 8 receives a trigger signal, the first thyristor 5 or the second thyristor 6 is turned on, causing the first energy storage capacitor 3 or the second energy storage capacitor 4 to discharge to the bypass switch trigger coil 13, triggering the bypass switch to close.

[0030] When the bypass switch trigger coil 13 in the circuit is in an open circuit fault state, the redundant trigger circuit for the bypass switch of the flexible DC converter valve of this embodiment works as follows:

[0031] 1) Before a redundant trigger circuit for a bypass switch of a flexible direct current converter valve is started, the voltage of the first energy storage capacitor 3 and the second energy storage capacitor 4 is 0V, the first thyristor trigger circuit 7 and the second thyristor trigger circuit 8 have no trigger signal, and the first thyristor 5 and the second thyristor 6 are in a cut-off state;

[0032] 2) After the power supply is powered on, since the bypass switch trigger coil 13 is in an open circuit fault state, the first energy storage capacitor 3 and the second energy storage capacitor 4 cannot be charged, and the voltage is always at 0 V. The first voltage detection circuit 15 and the second voltage detection circuit 14 can identify and alarm.

[0033] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A redundant trigger circuit for a bypass switch of a flexible direct current converter valve, characterized in that: The invention comprises a first charging resistor (1), a second charging resistor (2), a first energy storage capacitor (3), a second energy storage capacitor (4), a first thyristor (5), a second thyristor (6), a first thyristor trigger circuit (7), a second thyristor trigger circuit (8), a first diode (9), a second diode (10), a third diode (11), a fourth diode (12), a bypass switch trigger coil (13), a second voltage detection circuit (14) and a first voltage detection circuit (15), wherein the first charging resistor (1) and the second charging resistor The positive electrode of the first charging resistor (2) is connected in parallel to the positive electrode of the power supply, the negative electrode of the first charging resistor (1) is connected to the positive electrode of the first energy storage capacitor (3), the first energy storage capacitor (3) and the first voltage detection circuit (15) are connected in parallel, the negative electrode of the first charging resistor (1) is connected to the anode of the second thyristor (6), the gate of the second thyristor (6) is connected to one end of the second thyristor trigger circuit (8), the cathode of the second thyristor (6) is connected to the other end of the second thyristor trigger circuit (8) and the anode of the second diode (10), the first energy storage capacitor The negative electrode of the second charging resistor (2) is connected to the positive electrode of the second energy storage capacitor (4), the second energy storage capacitor (4) and the second voltage detection circuit (14) are connected in parallel, the negative electrode of the second charging resistor (2) is connected to the anode of the first thyristor (5), the gate of the first thyristor (5) is connected to one end of the first thyristor trigger circuit (7), the cathode of the first thyristor (5) is connected to the other end of the first thyristor trigger circuit (7) and the anode of the first diode (9). The cathode of the second energy storage capacitor (4) is connected to the cathode of the fourth diode (12), the anode of the first diode (9) is connected to the cathode of the third diode (11), the anode of the second diode (10) is connected to the cathode of the fourth diode (12), the cathodes of the first diode (9) and the second diode (10) are connected to one end of a bypass switch trigger coil (13), and the other end of the bypass switch trigger coil (13) is connected in parallel with the anodes of the third diode (11) and the fourth diode (12) to be connected to the negative electrode of the power supply; The first thyristor trigger circuit (7) and the second thyristor trigger circuit (8) both comprise an isolation transformer (16), a rectifier diode (17), a current limiting resistor (18) and an anti-parallel diode (19); the isolation transformer (16) receives a trigger signal, and one end of its output side drives the first thyristor (5) or the second thyristor (6) via the rectifier diode (17) and the current limiting resistor (18); the anode of the anti-parallel diode (19) is connected to the other end of the output side, and the cathode of the anti-parallel diode (19) is connected to the end of the current limiting resistor (18) away from the rectifier diode (17); The second voltage detection circuit (14) and the first voltage detection circuit (15) both comprise an upper sampling resistor (20), a lower sampling resistor (21) and a hysteresis comparator (22); the upper sampling resistor (20) and the lower sampling resistor (21) are connected in series and then connected in parallel to the first energy storage capacitor (3) or the second energy storage capacitor (4); the connection point between the upper sampling resistor (20) and the lower sampling resistor (21) is connected to the input end of the hysteresis comparator (22); and the output end of the hysteresis comparator (22) is the output end of the voltage detection circuit.

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