CN203301131U - Automatic switching circuit capable of protecting loops in switching of main line switch and by-pass switch - Google Patents

Abstract

An automatic switching circuit capable of protecting loops in the switching of a main line switch and a by-pass switch is provided. The automatic switching circuit is mainly composed of a sampling channel selection circuit, a main line switch working state loop and a by-pass switch working state loop. According to the automatic switching circuit capable of protecting the loops in the switching of the main line switch and the by-pass switch, current loops of the main line switch and the by-pass switch are accessed to differential protection simultaneously, and a digital quantity switching mode is adopted to switch voltage and current, and therefore, the switching of the current loops is free of possibility of open-circuit states, as a result, harm to personal safety and damage to equipment caused by the open-circuit states of the current loops can be prevented; the differential protection can be automatically locked when the switching of voltage and current loops is performed, and therefore, possibility of protection mal-operation can be decreased; remote operation-enabled automatic switching can be realized, and therefore, the requirement for unmanned attendance of a transformer substation can be satisfied, and therefore, safe and reliable operation of microcomputer transformer protection under different operating modes can be realized.

Description

Automatic switching circuit of the protection circuit when the main line switch and bypass switch are switched

technical field

The utility model belongs to the technical field of high-voltage power transmission and transformation, in particular to an automatic switching circuit for protecting a circuit when a main line switch and a bypass switch are switched.

Background technique

The rapid development of today's microcomputer control technology has exposed many obvious deficiencies in the traditional secondary protection circuit technology in the current power system; gradually applying the microcomputer protection device to the existing power system that is already in operation, enhancing the existing power The level of automation, digitalization and intelligence of the system is a major issue facing the current power control technology.

Fig. 1 is a schematic diagram of the connection between the main line switch and the bypass switch as backups in the prior art. As shown in Figure 1, in the current 220KV high-voltage power substation system, the main line switch DLb and the bypass switch DLp are often used in parallel as backup connections; when the secondary protection circuit uses a computer-based protection device WB, due to The microcomputer protection device WB is only connected to a group of input sampling terminals, and respectively collects the signals of the switch current signal terminal Iib of the local line and the switch voltage signal terminal Vib of the local line, so the microcomputer protection device WB can only protect the switch DLb of the local line; In this case, when the bypass switch DLp is used to replace the main line switch DLb, or the bypass switch DLp restores the main line switch DLb to operate, the protection current and voltage circuit switching, and the switching of the protection outlet pressure plate are all controlled by Operators do it manually.

The disadvantages of this manual switching method are: 1) the current loop is easy to open during the switching process, which endangers the safety of the operating personnel and equipment; when switching the current and voltage loops, the protection must be turned off first, and then put into protection after switching; 2) The operation steps are cumbersome, and it is easy to cause misoperation of the differential protection.

Contents of the invention

In order to solve the above problems, the purpose of this utility model is to provide an automatic switching circuit for the protection circuit when the main line switch and the bypass switch are switched.

In order to achieve the above-mentioned purpose, the automatic switching circuit of the protection circuit provided by the utility model is mainly composed of three parts: the sampling channel selection circuit, the working state circuit of the main line switch and the working state circuit of the bypass switch. : The switch working status loop of the main line is connected with the sampling channel selection circuit, which is used to detect the status signal of the switch of the main line, and transmit the signal to the sampling channel selection circuit; the bypass switch working status loop is connected with the sampling channel selection circuit, used It is used to detect the state signal of the bypass switch and transmit the signal to the sampling channel selection circuit; the two groups of sampling channel selection circuit use input channels to communicate with the current/voltage signal Iib/Vib of the main line and the current/voltage signal Iip of the bypass switch respectively. /Vip is connected, which is used to automatically select the current/voltage signal of the main line switch and the current/voltage signal of the bypass switch according to the state signals of the main line switch and the bypass switch.

The sampling channel selection circuit includes: a microcomputer protection device WB, a first optocoupler G1, a second optocoupler G2, resistors R1-R4 and normally open contacts QJ1, QJ2; wherein: the microcomputer protection device WB is a microcomputer Model type transformer protector, which is equipped with two sets of input sampling ports, the two input sampling ports of the first group are respectively connected with the local line voltage signal terminal Vib and the local line current signal terminal Liib, used to collect the local line switch DLb Voltage and current values; the two input sampling ports of the second group are respectively connected to the bypass voltage signal terminal Vip and the bypass current signal terminal Iip to collect the voltage and current value of the bypass switch DLp; the microcomputer protection device WB is equipped with two switching value input channels, the first input channel is connected with the normally closed contact QJ1 through the first optocoupler G1, and is used to collect the status signal of the switch DLb of the line through the normally closed contact QJ1; the second input channel is connected through the second The second optocoupler G2 is connected with the normally closed contact QJ2, and is used to collect the state signal of the bypass switch DLp through the normally closed contact QJ2; the collector of the first optocoupler G1 is connected to the power supply Vin through the resistor R2, and its emitter is connected to the first The input channel is connected, the anode of the light-emitting diode of the first optocoupler G1 is connected to the external power supply Vout through the resistor R1, and the cathode of the light-emitting diode is connected to the ground wire of the external power supply through the normally open contact QJ1; the collector of the second optocoupler G2 It is connected to the power supply Vin through the resistor R4, and its emitter is connected to the second input channel. The anode of the light-emitting diode of the second optocoupler G2 is connected to the external power supply Vout through the resistor R3, and the cathode of the light-emitting diode is connected to the external power supply through the normally open contact QJ2. connected to the power ground.

The switch working state circuit of this line includes: normally open contact YK1, terminal 2 and terminal 4, terminal 1 and terminal 3 of transfer switch ZK, normally open contact FJ1, relay coil QJ1 and terminal 1 and terminal 3 of changeover switch QK , where: the normally open contact YK1 is the relay contact of the remote control main line; the transfer switch ZK is the remote control/local control transfer switch. Open; in the bypass position, terminal 2 is disconnected from terminal 4, and terminal 1 is connected to terminal 3; the normally open contact FJ1 is the auxiliary contact of the main line switch; the relay coil QJ1 is the relay coil for the working state of the main line switch; the changeover switch QK It is the main line/bypass switch. When the main line is in the position, terminal 1 and terminal 3 on it are connected, and in the bypass position, terminal 1 and terminal 3 are disconnected;

One end of the normally open contact YK1 is connected to the DC bus +KM, and the other end is connected in series with the terminal 2 and terminal 4 of the transfer switch ZK, the normally open contact FJ1 and the relay coil QJ1, and then connected to the DC bus -KM; Terminal 1 of QK is connected to DC bus +KM, terminal 3 of switch QK is connected to terminal 1 of transfer switch ZK, terminal 3 of transfer switch ZK is connected to terminal 4 of transfer switch ZK.

The bypass switch working state circuit includes: normally open contact YK2, terminal 6 and terminal 8, terminal 5 and terminal 7 of transfer switch ZK, normally open contact FJ2, relay coil QJ2 and terminal 2 and terminal 4 of switch QK , where: the normally open contact YK2 is the remote control bypass working relay contact; the transfer switch ZK is the remote control/local control transfer switch, in the remote position, the terminal 6 and terminal 8 on it are connected, and the terminal 5 and terminal 7 are disconnected open; in the bypass position, terminal 6 is disconnected from terminal 8, and terminal 5 is connected to terminal 7; the normally open contact FJ2 is the auxiliary contact of the bypass switch; the relay coil QJ2 is the relay coil in the working state of the bypass switch; the changeover switch QK is Main line/bypass switch, when in the main line position, terminal 2 and terminal 4 on it are disconnected, and in bypass position, terminal 2 and terminal 4 are connected;

One end of the normally open contact YK2 is connected to the DC bus +KM, and the other end is connected in series with the terminal 6 and terminal 8 of the transfer switch ZK, the normally open contact FJ2 and the relay coil QJ2, and then connected to the DC bus -KM; Terminal 2 of QK is connected to DC bus +KM, terminal 4 of changeover switch QK is connected to terminal 5 of changeover switch ZK, terminal 7 of changeover switch ZK is connected to terminal 8 of changeover switch ZK.

The microcomputer protection device is PST-1200 microcomputer transformer protector.

The utility model provides an automatic switching circuit for the protection circuit when the main line switch and the bypass switch are switched. Switching, so that there is no possibility of an open circuit in the switching of the current loop, thus preventing the harm to the human body and equipment caused by the open circuit of the current loop; and when the current and voltage loops are switched, the differential protection is automatically blocked, reducing the probability of protection misoperation; and it can be remotely controlled. The operation is automatically switched, which meets the requirements of unattended substations, and realizes the safe and reliable operation of the microcomputer transformer protection in various operating modes.

Description of drawings

Fig. 1 is a schematic diagram of the connection between the main line switch and the bypass switch as backups in the prior art.

Fig. 2 is a schematic diagram of the composition of the protection circuit when the main line switch and the bypass switch are switched by the utility model.

Fig. 3 is a schematic diagram of the sampling channel selection circuit in the automatic switching circuit of the protection circuit when the main line switch and the bypass switch are switched by the utility model.

Fig. 4 is a schematic diagram of the working state circuit of the main line switch in the protection circuit when the bypass switch in the transformer protection provided by the utility model is switched.

Fig. 5 is a circuit schematic diagram of the working state of the bypass switch in the protection circuit when the bypass switch in the transformer protection provided by the utility model is switched.

Detailed ways

The automatic switching circuit of the protection circuit provided by the utility model when switching between the main line switch and the bypass switch will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 2, the automatic switching circuit of the protection circuit when the switch of the main line switch and the bypass switch provided by the utility model is mainly composed of the sampling channel selection circuit 1, the working state circuit 2 of the main line switch and the working state circuit 3 of the bypass switch. It is composed of several parts, among which: the working state circuit 2 of the main line switch is connected with the sampling channel selection circuit 1, which is used to detect the state signal of the main line switch and transmit the signal to the sampling channel selection circuit 1; the bypass switch working state circuit 3 is connected with the sampling channel selection circuit 1. The sampling channel selection circuit 1 is connected to be used to detect the state signal of the bypass switch, and the signal is sent to the sampling channel selection circuit 1; the two groups of the sampling channel selection circuit 1 adopt the input channel and the current/voltage signal Iib of the line switch respectively /Vib is connected with the current/voltage signal Iip/Vip of the bypass switch, and is used to automatically select the current/voltage signal of the local switch and the current/voltage signal of the bypass switch according to the state signals of the local switch and the bypass switch.

As shown in Figure 3, the sampling channel selection circuit 1 includes: a microcomputer protection device WB, a first optocoupler G1, a second optocoupler G2, resistors R1-R4 and normally open contacts QJ1, QJ2; wherein: micro The type protection device WB is a micro-type transformer protector, which is provided with two sets of input sampling ports. The two input sampling ports of the first group are respectively connected with the voltage signal terminal Vib of the main line and the current signal end Liib of the main line. It is used to collect the voltage and current value of the switch DLb of the main line; the two input sampling ports of the second group are connected to the bypass voltage signal terminal Vip and the bypass current signal terminal Iip respectively, and are used to collect the voltage and current of the bypass switch DLp value; the microcomputer protection device WB has two switch input channels, the first input channel is connected with the normally closed contact QJ1 through the first optocoupler G1, and is used to collect the state signal of the switch DLb of the line through the normally closed contact QJ1 ; The second input channel is connected to the normally closed contact QJ2 through the second optocoupler G2, and is used to collect the state signal of the bypass switch DLp through the normally closed contact QJ2; the collector of the first optocoupler G1 is connected to the power supply Vin through the resistor R2 , its emitter is connected to the first input channel, the anode of the light-emitting diode of the first optocoupler G1 is connected to the external power supply Vout through the resistor R1, and the cathode of the light-emitting diode is connected to the ground of the external power supply through the normally open contact QJ1; the second The collector of the second optocoupler G2 is connected to the power supply Vin through the resistor R4, and its emitter is connected to the second input channel. The anode of the light-emitting diode of the second optocoupler G2 is connected to the external power supply Vout through the resistor R3, and the cathode of the light-emitting diode It is connected to the ground wire of the external power supply through the normally open contact QJ2.

As shown in Figure 4, the switch working state circuit 2 of this line includes: normally open contact YK1, terminal 2 and terminal 4, terminal 1 and terminal 3 of transfer switch ZK, normally open contact FJ1, relay coil QJ1 and switch Terminal 1 and terminal 3 of QK, among them: the normally open contact YK1 is the relay contact of the remote control main line; the transfer switch ZK is the remote control/local control transfer switch, and the terminal 2 and terminal 4 on it are connected in the remote position , Terminal 1 is disconnected from terminal 3; in the bypass position, terminal 2 is disconnected from terminal 4, and terminal 1 is connected to terminal 3; the normally open contact FJ1 is the auxiliary contact of the main line switch; the relay coil QJ1 works as the main line switch Status relay coil; switch QK is the main line/bypass switch, when the main line is in position, terminal 1 and terminal 3 on it are connected, and in bypass position, terminal 1 and terminal 3 are disconnected;

One end of the normally open contact YK1 is connected to the DC bus +KM, and the other end is connected in series with the terminal 2 and terminal 4 of the transfer switch ZK, the normally open contact FJ1 and the relay coil QJ1, and then connected to the DC bus -KM; Terminal 1 of QK is connected to DC bus +KM, terminal 3 of switch QK is connected to terminal 1 of transfer switch ZK, terminal 3 of transfer switch ZK is connected to terminal 4 of transfer switch ZK.

As shown in Figure 5, the bypass switch working state circuit 3 includes: normally open contact YK2, terminal 6 and terminal 8, terminal 5 and terminal 7 of transfer switch ZK, normally open contact FJ2, relay coil QJ2 and switch Terminal 2 and terminal 4 of QK, among them: the normally open contact YK2 is the remote control bypass working relay contact; the transfer switch ZK is the remote control/local control transfer switch, in the remote position, the terminal 6 and terminal 8 on it are connected , Terminal 5 is disconnected from terminal 7; in the bypass position, terminal 6 is disconnected from terminal 8, and terminal 5 is connected to terminal 7; the normally open contact FJ2 is the auxiliary contact of the bypass switch; the relay coil QJ2 is in the working state of the bypass switch Relay coil; switch QK is the main line/bypass switch, when the main line is in position, terminal 2 and terminal 4 on it are disconnected, and in bypass position, terminal 2 and terminal 4 are connected;

One end of the normally open contact YK2 is connected to the DC bus +KM, and the other end is connected in series with the terminal 6 and terminal 8 of the transfer switch ZK, the normally open contact FJ2 and the relay coil QJ2, and then connected to the DC bus -KM; Terminal 2 of QK is connected to DC bus +KM, terminal 4 of changeover switch QK is connected to terminal 5 of changeover switch ZK, terminal 7 of changeover switch ZK is connected to terminal 8 of changeover switch ZK.

The microcomputer protection device is PST-1200 microcomputer transformer protector.

The working principle of the automatic switching circuit of the protection circuit when the switch of the main line switch and the bypass switch provided by the utility model is: the protection device WB of the microcomputer is to the input current signal terminals Iib, Iip and the input voltage of the main line switch DLb and the bypass switch DLp The signal terminals Vib and Vip are sampled, and the microcomputer protection device WB detects the status of the normally open contacts QJ1 and QJ2 through the digital input channel. When the switch DLb of the main line is running, the normally open contact QJ1 is closed, and the normally open contact QJ2 is disconnected. At this time, the microcomputer protection device WB selects the current signal terminal Iib and the voltage signal terminal Vib of the main line switch DLb for sampling, and obtains Corresponding conversion data; when the bypass switch DLp replaces the main line switch DLb, the normally open contact QJ2 is closed, and the normally open contact QJ1 is disconnected. At this time, the microcomputer protection device WB will use the current signal of the bypass switch DLp The terminal Iip and the voltage signal terminal Vip are sampled to obtain the corresponding conversion data, so as to realize the automatic switching of the transformer differential protection current and voltage circuits. If the microcomputer protection device WB detects that the normally open contact QJ1 and the normally open contact QJ2 are closed or disconnected at the same time, an alarm signal will be issued and the protection exit will be blocked at the same time.

The automatic switching circuit of the protection circuit provided by the utility model also has a remote control function when switching between the main line switch and the bypass switch: when the remote/local changeover switch ZK is in a remote position, it can be realized through the contacts YK1 and YK2 of the remote control relay. The transition of the working state of the line/bypass switch, the protection outlet pressure plate jumps the switch of the line/bypass switch pressure plate, and the other contacts of the relay QJ1 and QJ2 can drive the intermediate relay to switch. Due to the automatic switching of current and voltage circuits and protection outlets, the protection is blocked at the same time of switching, so it can meet the requirements of unattended substations.

Claims (5)

1. an automatic switching circuit of protection circuit when a main line switch and a bypass switch are switched, it is characterized in that: described automatic switching circuit is mainly composed of sampling channel selection circuit (1), main line switch working state loop (2) and The bypass switch working state circuit (3) is composed of three parts, among which: the main line switch working state circuit (2) is connected with the sampling channel selection circuit (1), which is used to detect the state signal of the main line switch and transmit the signal to The sampling channel selection circuit (1); the bypass switch working state loop (3) is connected with the sampling channel selection circuit (1), used to detect the state signal of the bypass switch, and transmit the signal to the sampling channel selection circuit (1) Two groups of sampling channel selection circuits (1) adopt input channels to be connected with the main line switch current/voltage signal Iib/Vib and the bypass switch current/voltage signal Iip/Vip respectively, for according to the main line switch and the bypass switch Automatically select the current/voltage signal of the main line switch and the current/voltage signal of the bypass switch. 2. The automatic switching circuit of the protection circuit when the main line switch and the bypass switch are switched according to claim 1, characterized in that: the sampling channel selection circuit (1) includes: a microcomputer protection device WB, a first Optocoupler G1, second optocoupler G2, resistors R1-R4 and normally open contacts QJ1, QJ2; among them: the microcomputer protection device WB is a microcomputer transformer protector, which sets two sets of input sampling interfaces, the first group The two input sampling ports of the second group are respectively connected with the local line voltage signal terminal Vib and the local line current signal terminal Liib to collect the voltage and current value of the local line switch DLb; the two input sampling ports of the second group are respectively connected with the bypass The voltage signal terminal Vip is connected with the bypass current signal terminal Iip, which is used to collect the voltage and current value of the bypass switch DLp; The coupling G1 is connected with the normally closed contact QJ1, which is used to collect the state signal of the switch DLb of the main line through the normally closed contact QJ1; the second input channel is connected with the normally closed contact QJ2 through the second optocoupler G2, and is used to pass the normally closed contact QJ2 collects the state signal of the bypass switch DLp; the collector of the first optocoupler G1 is connected to the power supply Vin through the resistor R2, and its emitter is connected to the first input channel, and the anode of the light-emitting diode of the first optocoupler G1 is connected to the power supply Vin through the resistor R1 The external power supply Vout is connected, and the cathode of the light-emitting diode is connected to the external power supply ground through the normally open contact QJ1; the collector of the second optocoupler G2 is connected to the power supply Vin through the resistor R4, and its emitter is connected to the second input channel , the anode of the light-emitting diode of the second optocoupler G2 is connected to the external power supply Vout through the resistor R3, and the cathode of the light-emitting diode is connected to the ground of the external power supply through the normally open contact QJ2. 3. The automatic switching circuit of the protection circuit when switching between the main line switch and the bypass switch according to claim 1, characterized in that: The switch working state circuit (2) of this line includes: normally open contact YK1, terminal 2 and terminal 4, terminal 1 and terminal 3 of transfer switch ZK, normally open contact FJ1, relay coil QJ1 and terminal 1 of transfer switch QK and terminal 3, wherein: the normally open contact YK1 is the relay contact of the remote control main line; the transfer switch ZK is the remote control/local control transfer switch. Terminal 3 is disconnected; in the bypass position, terminal 2 is disconnected from terminal 4, and terminal 1 is connected to terminal 3; the normally open contact FJ1 is the auxiliary contact of the main line switch; the relay coil QJ1 is the relay coil for the working state of the main line switch; The switch QK is the main line/bypass switch. When the main line is in the position, terminal 1 and terminal 3 on it are connected, and in the bypass position, terminal 1 and terminal 3 are disconnected; One end of the normally open contact YK1 is connected to the DC bus +KM, and the other end is connected in series with the terminal 2 and terminal 4 of the transfer switch ZK, the normally open contact FJ1 and the relay coil QJ1, and then connected to the DC bus -KM; Terminal 1 of QK is connected to DC bus +KM, terminal 3 of switch QK is connected to terminal 1 of transfer switch ZK, terminal 3 of transfer switch ZK is connected to terminal 4 of transfer switch ZK. 4. The automatic switching circuit of the protection circuit when switching between the main line switch and the bypass switch according to claim 1, characterized in that: the working state circuit (3) of the bypass switch includes: a normally open contact YK2, a transfer switch Terminal 6 and terminal 8, terminal 5 and terminal 7 of ZK, normally open contact FJ2, relay coil QJ2 and terminal 2 and terminal 4 of changeover switch QK, wherein: normally open contact YK2 is the remote control bypass working relay contact; changeover switch ZK is a switch for remote control/local control. In the remote position, terminal 6 is connected to terminal 8, and terminal 5 is disconnected from terminal 7. In bypass position, terminal 6 is disconnected from terminal 8, and terminal 5 is connected to terminal 8. 7 is connected; the normally open contact FJ2 is the auxiliary contact of the bypass switch; the relay coil QJ2 is the relay coil of the bypass switch working state; the changeover switch QK is the main line/bypass switch. Disconnect from terminal 4, and connect terminal 2 to terminal 4 in bypass position; One end of the normally open contact YK2 is connected to the DC bus +KM, and the other end is connected in series with the terminal 6 and terminal 8 of the transfer switch ZK, the normally open contact FJ2 and the relay coil QJ2, and then connected to the DC bus -KM; Terminal 2 of QK is connected to DC bus +KM, terminal 4 of changeover switch QK is connected to terminal 5 of changeover switch ZK, terminal 7 of changeover switch ZK is connected to terminal 8 of changeover switch ZK. 5. The automatic switching circuit of the protection circuit when switching the main line switch and the bypass switch according to claim 2, characterized in that: said microcomputer-based protection device is a PST-1200 microcomputer-based transformer protector.

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