CN203871851U - Module-combined high-voltage direct-current circuit breaker - Google Patents

Abstract

The utility model provides a module-combined high-voltage direct-current circuit breaker which comprises a switch block, a diode, a resistor and a mechanical switch. The switch block includes N half-bridge modules, and N is a positive integer. Each half-bridge module is composed of a capacitor, a first IGBT and a second IGBT. Compared with the prior art, the module-combined high-voltage direct-current circuit breaker adopts a universal half-bridge module, which can greatly reduce the cost. The N sub modules are connected in series, which reduces the voltage stress on the IGBTs of the sub modules after switching off. Discharge of the capacitors of the half-bridge modules can be controlled accurately, the half-bridge modules gradually discharge, and the discharge current is effectively reduced.

Description

Modular Combination High Voltage DC Circuit Breaker

technical field

The utility model relates to the field of high voltage direct current transmission (HVDC) protection, in particular to a module combined high voltage direct current circuit breaker.

Background technique

With the continuous development of high-voltage direct current transmission, the demand for high-voltage direct current circuit breakers is becoming more and more extensive. However, there are two major technical problems in the development of high-voltage DC circuit breakers: ① There is no natural zero-crossing point for DC current, and the DC arc is not easy to extinguish; ② The impedance of the DC system is much smaller than that of the AC system, and its short-circuit current increases extremely fast.

At present, high-voltage DC circuit breakers mainly include mechanical DC circuit breakers, solid-state DC circuit breakers and hybrid DC circuit breakers. The mechanical DC circuit breaker is based on the structure of the conventional mechanical AC circuit breaker, adding an oscillating commutation circuit that can automatically form the zero-crossing point of the high-frequency oscillating current during the process of breaking the DC current. It has stable operation, strong load capacity, and It has the advantages of small state loss, etc., but its contacts are easily damaged by the breaking arc, the breaking capacity is limited, and the fault current cut-off time is long. The solid-state DC circuit breaker uses half-controlled or fully-controlled power electronic switching devices to realize the on-off control of the current. It has the advantages of no contact, fast switching and no sound, accurate and controllable switches, and long life. Power electronic devices are prone to overvoltage and overcurrent, high on-state loss of devices, and bulky cooling systems. The hybrid high-voltage DC circuit breaker combines mechanical DC circuit breakers and solid-state DC circuit breakers, and integrates their advantages. It has the advantages of small on-state loss, fast and controllable breaking, no arc and no sound, and no special cooling equipment is required. Hybrid high-voltage DC circuit breakers generally use power electronic switches to shunt mechanical switches, and use capacitor clamping circuits to provide forward conduction voltage for shunted power electronic switches, and at the same time clamp power electronic switches and mechanical switches, but the clamp capacitor The discharge cannot be precisely controlled.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the above-mentioned prior art, and propose a modular high-voltage DC circuit breaker.

The technical solution adopted by the utility model is: a modular high-voltage DC circuit breaker, including a switch group, a diode, a resistor and a mechanical switch; the switch group includes N half-bridge modules; N is a positive integer.

Preferably, the half-bridge module is composed of a capacitor, a first IGBT and a second IGBT; wherein, the anode of the capacitor is connected to the collector of the first IGBT, the emitter of the first IGBT is connected to the collector of the second IGBT, and the capacitor The cathode of the second IGBT is connected to the emitter of the second IGBT; the collector of the second IGBT is used as the first output terminal of the half-bridge module, and the emitter of the first IGBT is used as the second output terminal of the half-bridge module.

The half-bridge modules in the switch group are connected sequentially, the second output end of the i- th half-bridge module is connected to the first output end of the i +1 half-bridge module of the switch group, and the value of i is 1~ N -1; the first output end of the first half-bridge module of the switch group is used as the upper end of the switch group, and the second output end of the Nth half-bridge module of the switch group is used as the lower end of the switch group.

The upper end of the switch group is connected to one end of the resistor and the cathode of the diode, the anode of the diode is connected to the other end of the resistor and one end of the mechanical switch, and the other end of the mechanical switch is connected to the lower end of the switch group; the two ends of the mechanical switch are used as modules Combine the two ends of the HVDC circuit breaker.

Compared with the prior art, the utility model has the following advantages: the use of a general-purpose half-bridge module can reduce the cost very well; N sub-modules are connected in series, which reduces the voltage stress on each IGBT of each sub-module after opening ; The discharge of the capacitor of each half-bridge module can be precisely controlled, and each half-bridge module is discharged successively, effectively reducing the discharge current. Compared with the existing mechanical DC circuit breaker and solid-state DC circuit breaker, the modular combination high-voltage DC circuit breaker provided by the utility model has the advantages of the hybrid DC circuit breaker; compared with the existing hybrid DC circuit breaker, the utility model The modular combination HVDC circuit breaker provided by the new model adopts a general-purpose half-bridge module, which can reduce the cost very well. In addition, it can precisely control the discharge of the capacitance of each half-bridge module.

Description of drawings

Fig. 1 is the circuit structure diagram of the modular combination high-voltage DC circuit breaker of the present invention;

Fig. 2 is the circuit structure diagram of the half-bridge module of the modular combination high-voltage DC circuit breaker of the present invention;

Fig. 3 is an example circuit of the module combination HVDC circuit breaker shown in Fig. 1 ( N = 2);

Figures 4a to 4g are the seven working modes of the example circuit shown in Figure 3, respectively.

Detailed ways

In order to further illustrate the content and characteristics of the utility model, the specific implementation of the utility model will be described in detail below in conjunction with the accompanying drawings, but the implementation of the utility model is not limited thereto.

Referring to Fig. 1, the modular combination high-voltage direct current circuit breaker of the present invention is made up of switch group 8, diode 1, resistance 2 and mechanical switch 3; Said switch group 8 comprises N half-bridge modules SM; The value of N is a positive integer .

When _the port voltage _of the module combination HVDC breaker is Vb , the voltage stress of each IGBT on each half-bridge module 8 is only Vb / N .

As shown in Figure 2, the half-bridge module SM is composed of a capacitor 9, a first IGBT 10 and a second IGBT 11; wherein, the anode of the capacitor 9 is connected to the collector of the first IGBT 10, and the emitter of the first IGBT 10 is connected to the first IGBT 10. The collector of the second IGBT 11 is connected, the negative pole of the capacitor 9 is connected to the emitter of the second IGBT 11; the collector of the second IGBT 11 is used as the first output terminal 4 of the half bridge module SM, and the emitter of the first IGBT 11 is used as the half The second output 5 of the bridge module SM.

The second output terminal 5 of the ith half-bridge module of the switch group 8 is connected to the first output terminal 4 of the i +1 half-bridge module of the switch group 8, and the value of i is 1~ N -1; the switch group The first output terminal 4 of the first half-bridge module of 8 is used as the upper terminal of the switch group 8, and the second output terminal 5 of the Nth half-bridge module of the switch group 8 is used as the lower terminal of the switch group 8.

The upper end of the switch group 8 is connected with one end of the resistor 2 and the cathode of the diode 1, the anode of the diode 1 is connected with the other end of the resistor 2, one end of the mechanical switch 3, and the other end of the mechanical switch 3 is connected with the lower end of the switch group 8; the mechanical switch The two ends 6 and 7 of 3 are used as the two ends of the module combination high-voltage direct current circuit breaker.

Taking the circuit with N =2 as an example, the working process of the modular high-voltage DC circuit breaker of the present invention is analyzed in detail. As shown in Figure 3, the switch group 8 is composed of two half-bridge modules SM.

The example circuit shown in Figure 3 has seven working modes, as shown in Figures 4a, 4b, 4c, 4d, 4e, 4f, and 4g. The dotted lines in the figure indicate the corresponding circuit breaks, and the dotted lines with arrows are the current paths. The working process of shutting off the short-circuit current of the module-combined high-voltage DC circuit breaker is introduced in detail below. Mode 1: When the DC system is running normally, the mechanical switch 4 is closed, and the current flows through the circuit breaker, and the current path is shown in Figure 4a.

Mode 2: When a short-circuit fault occurs in the DC system, the short-circuit current increases instantaneously and flows through the mechanical switch 4 . Detect the current flowing through the circuit breaker. When the current flowing through the circuit breaker is greater than the set value, the mechanical switch 4 is broken, and an arc is generated between the contacts of the mechanical switch 4; at the same time, the gate of the second IGBT of the two half-bridge modules A high-level signal is given to both poles, so that the second IGBTs of the two half-bridge modules are in a pre-conduction state. Due to the arc voltage of the mechanical switch 4, the anti-parallel diodes and diode 3 of the first IGBT of the two half-bridge modules are both turned on, and the short-circuit current passes through the anti-parallel diode and diode 3 of the first IGBT of the two half-bridge modules to the two The capacitor 1 of the half-bridge module is charged until the voltage of the capacitor 1 of the two half-bridge modules is equal to the turn-on voltage of the second IGBT of the two half-bridge modules. The current path is shown in Figure 4b.

Mode 3: When the voltage of capacitor 1 of the half-bridge module is equal to the turn-on voltage of the second IGBT of the half-bridge module, the second IGBT of the half-bridge module is turned on, and the first IGBTs of the two half-bridge modules are turned on at the same time The anti-parallel diodes of all the switches are turned off, and the short-circuit current flows through the second IGBT of the half-bridge module, which reduces the short-circuit current flowing through the mechanical switch 4 . The current path is shown in Figure 4c.

Mode 4: due to the shunting of the second IGBT of the half-bridge module, the short-circuit current flowing through the mechanical switch 4 is reduced, the arc between the contacts of the mechanical switch 4 is extinguished, and the mechanical switch 4 is completely disconnected. The current path is shown in Fig. 4d.

Mode 5: As shown in Figure 4e, after the arc between the 4 contacts of the mechanical switch is extinguished, a low-level signal is given to the second IGBT gates of the two half-bridge modules, so that the second gates of the two half-bridge modules The IGBT is turned off, thereby completing the removal of the short-circuit fault of the DC system.

Mode 6: After the short-circuit fault of the DC system is eliminated, close the mechanical switch 4 again. Due to the clamping of the capacitor 1 of the two half-bridge modules, the mechanical switch 4 is closed and conducted at low voltage, and the DC system operates normally; at the same time, Give the gate of the first IGBT of the first half-bridge module a high level to turn it on, and the capacitor 1 of the first half-bridge module passes through the first IGBT and the second half-bridge of the first half-bridge module The anti-parallel diode of the second IGBT of the module, the mechanical switch 4 and the resistor 2 are discharged until the voltage of the capacitor 1 of the first half-bridge module is zero. The current path is shown in Fig. 4f.

Mode 7: After a period of time, give the gate of the first IGBT of the first half-bridge module a low level to turn it off, and give the gate of the first IGBT of the second half-bridge module a high level , to turn it on; the capacitor 1 of the second half-bridge module is discharged through the first IGBT of the second half-bridge module, the anti-parallel diode of the second IGBT of the first half-bridge module, the mechanical switch 4 and the resistor 2, Until the voltage of capacitor 1 of the second half-bridge module is zero. The current path is shown in Fig. 4g.

The above-mentioned embodiment is a preferred implementation mode of the present utility model, but the implementation mode of the present utility model is not limited by the described embodiment, and any other changes, modifications, modifications, Substitution, combination, and simplification should all be equivalent replacement methods, and are all included in the protection scope of the present utility model.

Claims (4)

1. module combined high pressure DC circuit breaker, is characterized in that: comprise switches set (8), diode (1), resistance (2) and mechanical switch (3); Described switches set (8) comprises nindividual half-bridge module (SM); nvalue be positive integer.

2. module combined high pressure DC circuit breaker according to claim 1, is characterized in that: half-bridge module (SM) is by electric capacity (9), an IGBT(10) and the 2nd IGBT(11) form; Wherein, the positive pole of electric capacity (9) and an IGBT(10) collector electrode be connected, an IGBT(10) emitter-base bandgap grading and the 2nd IGBT(11) collector electrode be connected, the negative pole of electric capacity (9) and the 2nd IGBT(11) emitter-base bandgap grading be connected; The 2nd IGBT(11) collector electrode as first output (4) of half-bridge module (SM), an IGBT(11) emitter-base bandgap grading as second output (5) of half-bridge module (SM).

3. module combined high pressure DC circuit breaker according to claim 2, is characterized in that: the half-bridge module in switches set (8) connects in turn, the ithe of second output (5) of individual half-bridge module and switches set (8) ifirst output (4) of+1 half-bridge module connects, ifor the sequence number of half-bridge module, ivalue be 1 ~ n-1; First output (4) of the 1st half-bridge module of switches set (8) is as the upper end of switches set (8), of switches set (8) nsecond output (5) of individual half-bridge module is as the lower end of switches set (8).

4. module combined high pressure DC circuit breaker according to claim 3, it is characterized in that: the upper end of switches set (8) is connected with the negative electrode of one end of resistance (2), diode (1), the anode of diode (1) is connected with one end of the other end of resistance (2), mechanical switch (3), and the other end of mechanical switch (3) is connected with the lower end of switches set (8); The two ends (6,7) of mechanical switch (3) are as the two ends of module combined high pressure DC circuit breaker.