CN201174597Y - 10kV reactive compensating capacitor switch - Google Patents

Abstract

The utility model relates to a 10kV reactive power compensation capacitor switching switch, which is composed of three relays (or circuit breakers) and a control circuit, wherein the main contacts of each relay are respectively connected in series in the three phases of the main circuit, and the main contacts The input and output of the head are respectively connected to the power grid and the capacitor (capacitor bank), the control coil of the relay is connected to the output control line of the control circuit, and there are thyristors connected in parallel on the main contacts of the two relays. Yes: The thyristor connected in parallel on the main contact consists of at least two thyristors connected in series. Since the utility model adopts a circuit structure in which relay contacts and silicon controlled rectifiers are connected in parallel, and cooperates with the switching strategy and timing selection controlled by software, no inrush current will be generated when the capacitor is switched on, and arcing will not occur during switching, thus The service life of the relay is extended, at least two thyristors are used in series to solve the defect of insufficient withstand voltage, and the isolation circuit is used to solve the defect that the high-voltage circuit and the control circuit are easily disturbed.

Description

10kV reactive power compensation capacitor switching switch

technical field

The utility model belongs to a switching switch of an industrial capacitor compensation cabinet, in particular to a switching switch of a 10kV reactive power compensation capacitor.

Background technique

At present, relays (contactors) or circuit breakers are often used as the switching switches of capacitors for industrial capacitor compensation cabinets. Due to the large capacity of capacitors, there is a large inrush current in the main circuit when the capacitors are switched on, and the relays are in the process of switching. The contacts will pull the arc, which will affect the service life of the relay and the compensation capacitor. If the thyristor is used as the switching switch of the capacitor, since the thyristor has a certain voltage drop when it is turned on, it will generate a lot of heat when a large current flows. A larger radiator must be installed, which not only increases the volume of the switch, but also has a large power loss. Although the published 200520099258.8 Chinese patent solves the above-mentioned problems, when it is applied to a 10KV high-voltage power grid, there are defects such as insufficient withstand voltage of the thyristor and easy interference between the high-voltage circuit and the control circuit.

Contents of the invention

The purpose of this utility model is to provide a 10kV reactive power compensation capacitor switching switch that does not generate inrush current and has low power consumption, and can be applied to a 10KV high-voltage power grid, so as to overcome the above-mentioned shortcomings.

In order to achieve the above object, the utility model is composed of three relays (or circuit breakers) and a control circuit, wherein the main contacts of each relay are respectively connected in series in the three phases of the main circuit, and the input and output of the main contacts are respectively connected with the three phases of the main circuit. The power grid is connected to the capacitor (capacitor bank), and the control coil of the relay is connected to the output control line of the control circuit. The main contacts of the two relays are connected in parallel with thyristors, and the trigger terminals of the thyristors are connected to the control circuit. The output control line is connected, and its characteristic is: the thyristor connected in parallel on the main contact is composed of at least two thyristors connected in series.

An isolation circuit is connected between the trigger terminal of each thyristor and the output control line of the control circuit.

The above-mentioned control circuit is composed of a central processing unit CPU, an amplifying circuit and a trigger signal generating circuit, wherein the data input terminal of the central processing unit CPU is connected with the phase test signal and the switching signal, and the relay control signal output of the central processing unit CPU and the thyristor The control signal output is connected to the input terminal of the amplifying circuit, the output terminal of the amplifying circuit is respectively connected to the control coil of the relay and the input terminal of the trigger signal generating circuit, and the output terminal of the trigger signal generating circuit is connected to the trigger of the thyristor through the isolation circuit. end connected.

Since the utility model adopts a circuit structure in which relay contacts and silicon controlled rectifiers are connected in parallel, and cooperates with the switching strategy and timing selection controlled by software, no inrush current will be generated when the capacitor is switched on, and arcing will not occur during switching, thus The service life of the relay is extended, at least two thyristors are used in series to solve the defect of insufficient withstand voltage, and the isolation circuit is used to solve the defect that the high-voltage circuit and the control circuit are easily disturbed.

Description of drawings

Fig. 1 is a schematic diagram of the connection structure of the main circuit of the present invention.

Fig. 2 is a functional block diagram of the utility model control circuit.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

The connection structure of the main circuit of the utility model is shown in Figure 1, in the figure, the SCRs AS1~ASn, the SCRs CS1~CSn and the magnetic latching relays K1, K2, K3 together form the main switch. The thyristor mainly implements the function of putting the compensation capacitor into the power grid Ua, Ub, Uc without impact or disconnecting it from the power grid Ua, Ub, Uc. The relays K1 and K3 are closed after the bidirectional thyristor is reliably connected, and the thyristor short circuit for normal operation. Relay K2 realizes the function of turning on or cutting off the circuit, and acts when there is no current.

The action sequence of inputting the compensation capacitor C in the utility model is as follows: first close the relay K2, then respectively connect the thyristors AS1~ASn, CS1~CSn respectively, and then close the relays K1 and K3; cut off the action of the compensation capacitor C The order is as follows: first, when the thyristors AS1~ASn, CS1~CSn are connected, the relays K1, K3 are turned off, then the trigger signals of the thyristors AS1~ASn, CS1~CSn are stopped, and finally the relay K2 is turned off. In the process of inputting the compensation capacitor C, after K2 is closed, the circuit does not form a loop, and there is no current. The thyristor AS1~ASn, CS1~CSn adopts the phase-selection connection method, that is, the voltage between the contactor fractures is 0V and can be triggered. The SCR is turned on, and the overcurrent multiple can be controlled within 2 times the rated current. In the process of removing the compensation capacitor, after stopping the trigger signals of the thyristors AS1~ASn, CS1~CSn, when the current crosses zero, the thyristors are naturally turned off, and the capacitor C is out of operation, which will not cause impact on the power grid. The switching on and off of relays K1 and K3 is completed under the condition that the thyristors AS1~ASn, CS1~CSn are bypassed, so the fracture will not draw arc; the relay K2 will not switch current, and the fracture will not pull arc. This switching method effectively protects the contacts of the relay, and greatly prolongs the service life of the relay and its corresponding compound switch and the withstand voltage capability of the thyristor. .

The core chip CPU of the control circuit of the present utility model (as shown in Figure 2) adopts 89C2051 single-chip microcomputer. The single-chip CPU accepts the switching and switching signals from the reactive power compensation controller, and the high level is switching, and the low level is switching. After the CPU receives the switching compensation capacitor signal, it sends corresponding signals to relay K2, thyristor AS1~ASn, CS1~CSn, relay K1, K3 respectively according to the designed action sequence (all high level means on , low level means disconnection). In order to ensure reliable action, there is a certain time interval between each two action signals, so as to ensure that before each action, the transient process of the previous action has ended, and the input points of the thyristor AS1~ASn, CS1~CSn trigger signals Respectively when relay K1 and relay K3 breakout voltage crosses zero. The above-mentioned working process is realized by software in the single-chip microcomputer 89C2051. According to the design of the program, when the single chip microcomputer receives the switching signal from the controller, the program will perform device initialization and phase detection work, and according to the program setting, select the appropriate timing (phase) to pass the isolation circuit to the corresponding SCR Issue an action command, or a relay issues an action command.

The utility model can also realize system power-off detection and power-off-phase detection. When the power fails, the switch will be reset in time to ensure that the system power-on switch is in an off state under any circumstances, and there will be no inrush current when power is on.

The content not described in detail in this specification belongs to the prior art known to those skilled in the art.

Claims (3)

1. A 10kV reactive power compensation capacitor switching switch is composed of three relays and a control circuit, wherein the main contacts of each relay are respectively connected in series with the three phases of the main circuit, and the input and output of the main contacts are respectively connected to the The power grid is connected to the capacitor, the control coil of the relay is connected to the output control line of the control circuit, and the main contacts of the two relays are connected in parallel with thyristors, and the trigger terminals of the thyristors are connected to the output control lines of the control circuit. Phase connection, characterized in that: the thyristor connected in parallel on the main contact is composed of at least two thyristors connected in series. 2. The 10kV reactive power compensation capacitor switching switch according to claim 1, characterized in that: an isolation circuit is connected between the trigger terminal of each thyristor and the output control line of the control circuit. 3. The 10kV reactive power compensation capacitor switching switch as claimed in claim 1, characterized in that: the control circuit is composed of a central processing unit CPU, an amplifying circuit and a trigger signal generating circuit, wherein the data input terminal of the central processing unit CPU and the phase The test signal is connected to the switching signal, the relay control signal output of the central processing unit CPU and the thyristor control signal output are connected to the input end of the amplifying circuit, and the output end of the amplifying circuit is respectively connected to the control coil of the relay and the trigger signal generating circuit. The input ends are connected, and the output end of the trigger signal generating circuit is connected with the trigger end of the thyristor through the isolation circuit.