Fast switching device for single-bus sectional power supply system

Abstract

The utility model belongs to the field of electrical technology, and discloses a fast switching device for a single-bus segmented power supply system, which aims at solving the problems in the segmented power supply system in the prior art and comprises a main switching loop, a control power supply fast switching loop, a voltage detection comparison loop, a zero-current over-current detection circuit and a PLC (Programmable Logic Controller) control loop, the main switching loop is used for providing rapid bypass switching for a standby breaker for opening, and the voltage detection comparison loop and the zero-current over-current detection circuit access a comparison detection logic signal to the PLC control loop. And the PLC control loop is used for outputting the detected voltage sag condition and an upper computer instruction to the main switching loop for switching and controlling the power supply switching of the power supply fast switching loop. When voltage sag occurs in a certain section of the bus or the power supply is withdrawn, the other section of the bus is quickly connected, so that the influence caused by the voltage sag is reduced or avoided; meanwhile, the problem that in a single-bus sectional power supply system, the operation mode is changed under the condition that equipment on a bus is not stopped, and loop closing operation is needed is solved.

Description

Technical Field

[0001] The utility model relates to the field of electrical technology, in particular to a single busbar segmented power supply system quick-cut device. Background Art

[0002] With the development and progress of society, it is well known that enterprises with continuous and stable production all need a stable power supply system. Due to short-circuit faults in the power system, the voltage of the entire system often drops (voltage "temporary sag") for 80-500ms. This voltage "temporary sag" mainly affects the low-voltage 380V power supply and distribution system due to undervoltage shutdown; in addition, the low-voltage 380V power supply and distribution system mostly adopts a single busbar segmented operation mode with two incoming power supplies. When one incoming power supply needs to be repaired or the power is cut off due to an accident, in order to ensure the continuous power supply of the two low-voltage busbars, the superior power department is often contacted to close the loop of the primary power supply of the two transformers of the low-voltage power supply (to avoid the superior power department's Due to uneven load distribution between the two power sources, an ultra-high circulating current is generated when the low-voltage 380V power source is connected in parallel, causing an accident). That is, close the connecting switch of the two 380V busbars to realize the parallel operation of the two 380V low-voltage single busbars, and then cut off the low-voltage incoming line that needs to be shut down as required, so as to shut down the electrical equipment on the power outage incoming line; after the power outage maintenance is completed, it is necessary to contact the superior power department again to close the primary power supply of the two transformers of the low-voltage power source before closing the 380V power outage maintenance incoming line switch to realize the parallel operation of the two 380V low-voltage single busbars, cut off the connecting switch of the two 380V busbars, and restore the separate operation mode of the two 380V single busbars.

[0003] From the above process, it can be seen that the operation is rather complicated and requires the mutual cooperation of two departments. In addition, after the two busbars on the primary side of the transformer are closed, there is also the problem of circulating current, and it is necessary to apply for the closing operation of the upper-level substation. The existing technology cannot solve the above technical problems. Utility Model Content

[0004] The utility model aims to solve the technical problems existing in the prior art segmented power supply system and provides a single bus segmented power supply system quick-cut device.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A single-busbar segmented power supply system fast-cut device, characterized in that it includes a main switching circuit, a control power fast-cut circuit, a voltage detection comparison circuit, a zero current overcurrent detection circuit and a PLC control circuit. The main switching circuit is used to provide fast bypass switching for the circuit breaker in standby mode. The voltage detection comparison circuit and the zero current overcurrent detection circuit connect the comparison detection logic signal to the PLC digital input point of the PLC control circuit. The PLC control circuit is used to output the detected voltage sag and the host computer instruction to the main switching circuit switching and the control power fast-cut circuit power switching through the PLC digital output point.

[0007] Furthermore, the main switching circuit includes a first circuit breaker QF1 connected to the first power supply, the first circuit breaker QF1 is connected to the first three-phase current transformer I1, the first three-phase current transformer I1 is connected to the bus end of a first distribution line, and also includes a second circuit breaker QF2 connected to the second power supply, the second circuit breaker QF2 is connected to the second three-phase current transformer I2, the second three-phase current transformer I2 is connected to the bus end of the second distribution line, a third circuit breaker QF3 is connected between the bus end of the first distribution line and the bus end of the second distribution line, and a bypass circuit is connected between the first power supply, the second power supply and the two ends of the third circuit breaker QF3.

[0008] Furthermore, the bypass circuit includes a seventh circuit breaker QF7 connected to the first power supply, the seventh circuit breaker QF7 is connected to the normally open contact of the third contactor KM3 of the main circuit, the normally open contact of the third contactor KM3 of the main circuit is connected to the reactor L and the normally open contact of the second contactor KM2 of the main circuit, the normally open contact of the second contactor KM2 of the main circuit is connected to the bus terminal of the second-stage distribution line, the other end of the reactor L is connected to the first thyristor V1 and the second thyristor V2 which are connected in reverse parallel, the gate switches of the first thyristor V1 and the second thyristor V2 are connected to the normally open contact of the first reed switch relay KR1, the first thyristor V1 and the second thyristor V2 are connected in reverse parallel, One end of the positive and negative poles of the thyristor V2 is connected to the normally open contact of the first contactor KM1 of the main circuit, and the other end of the normally open contact of the first contactor KM1 of the main circuit is connected to the busbar end of a section of the distribution line. The normally open contact of the fourth contactor KM4 of the main circuit is connected between the normally open contact of the first contactor KM1 of the main circuit and the positive and negative poles of the first thyristor V1 and the second thyristor V2. The normally open contact of the fourth contactor KM4 of the main circuit is connected to the eighth circuit breaker QF8, and the other end of the eighth circuit breaker QF8 is connected between the second power supply and the second circuit breaker QF2.

[0009] Furthermore, the control power supply fast-cutting circuit includes a fourth circuit breaker QF4 connected to the inlet end of the seventh circuit breaker QF7, and a fifth circuit breaker QF5 connected to the inlet end of the eighth circuit breaker QF8. The other end of the fourth circuit breaker QF4 is connected to a third thyristor V3 and a fourth thyristor V4 which are connected in reverse parallel. The gate switch between the third thyristor V3 and the fourth thyristor V4 is connected to a normally closed contact of a second reed switch relay KR2. The third thyristor V3 and the fourth thyristor V4 are connected to a section of the distribution line control power supply bus. The other end of the fifth circuit breaker QF5 is connected to a reverse parallel The fifth thyristor V5 and the sixth thyristor V6 are connected in series, and the gate switch between the fifth thyristor V5 and the sixth thyristor V6 is connected with the normally closed contact of the third reed switch relay KR3. The fifth thyristor V5 and the sixth thyristor V6 are connected with a two-section distribution line control power bus, and the two-section distribution line control power bus is also connected with the sixth circuit breaker QF6. The other end of the sixth circuit breaker QF6 is connected with the seventh thyristor V7 and the eighth thyristor V8 which are connected in reverse parallel, and the gate switch between the seventh thyristor V7 and the eighth thyristor V8 is connected with the normally open contact of the fourth reed switch relay KR4.

[0010] Furthermore, the voltage detection comparison loop includes a first rectifier bridge UR1 and a second rectifier bridge UR2, wherein one end of the AC input end of the first rectifier bridge UR1 is connected to a first resistor R1, the first resistor R1 is connected to an LA1 terminal, the LA1 terminal is connected to a first power supply, the other end of the AC input end of the first rectifier bridge UR1 is connected to an N phase of the first power supply, and a first voltage-dividing resistor R2 is connected in parallel to the DC positive and negative terminals of the first rectifier bridge UR1; one end of the AC input end of the second rectifier bridge UR2 is connected to a second resistor R4, the second resistor R4 is connected to an LA2 terminal, the LA2 terminal is connected to a second power supply, the other end of the AC input end of the second rectifier bridge UR2 is connected to an N phase of the second power supply, and a second voltage-dividing resistor R5 is connected in parallel to the DC positive and negative terminals of the second rectifier bridge UR2; the positive pole of the DC end of the first rectifier bridge UR1 is connected to a first current-limiting resistor R3, the other end of the first current-limiting resistor R3 is connected to an anode of a first optocoupler U1, and a cathode of the first optocoupler U1 is connected to The positive pole of the DC end of the second rectifier bridge UR2 is connected, and the positive pole of the DC end of the second rectifier bridge UR2 is also connected to the second current limiting resistor R6, the other end of the second current limiting resistor R6 is connected to the anode of the second optocoupler U2, the cathode of the second optocoupler U2 and the positive pole of the first voltage-dividing resistor R2 are connected to the third current limiting resistor R7, the other end of the third current limiting resistor R7 is connected to the cathode of the first voltage-regulating diode ZD1, the anode of the first voltage-regulating diode ZD1 is connected to the anode of the third optocoupler U3, the negative pole of the third optocoupler U3 is connected to the negative pole of the second voltage-dividing resistor R5, the positive pole of the second voltage-dividing resistor R5 is connected to the fourth current limiting resistor R8, the fourth current limiting resistor R8 is connected to the cathode of the second voltage-regulating diode ZD2, the anode of the second voltage-regulating diode ZD2 is connected to the anode of the fourth optocoupler U4, the cathode of the fourth optocoupler U4 is connected to the negative pole of the second voltage-dividing resistor R5, and the output ends of the first optocoupler U1, the second optocoupler U2, the third optocoupler U3, and the fourth optocoupler U4 are connected to the PLC control loop.

[0011] Furthermore, the zero current overcurrent detection circuit includes a third rectifier bridge UR3, the DC output end of the third rectifier bridge UR3 is connected to the series-connected diodes D1, D2, D3, and D4, the cathode of the D4 diode is connected to the voltage sampling resistor R10, the other end of the voltage sampling resistor R10 is connected to the negative terminal of the DC output end of the third rectifier bridge UR3, the series-connected diodes are connected in parallel with the first non-polar capacitor C2 and the fifth current limiting resistor R9, and the fifth current limiting resistor R9 is connected to the fifth optocoupler U5; the voltage sampling resistor R10 is connected in parallel with the second non-polar capacitor C2, one end of the second non-polar capacitor C2 is connected to the sixth current limiting resistor R11, the sixth current limiting resistor R11 is connected to the sixth optocoupler U6, the sixth optocoupler U6 is connected to the third voltage zener diode ZD3, the third voltage zener diode ZD3 is connected to the other end of the second non-polar capacitor C2, and the output ends of the fifth optocoupler U5 and the sixth optocoupler U6 are connected to the PLC control loop.

[0012] Furthermore, the three phases of the first three-phase current transformer I1 and the three phases of the second three-phase current transformer I2 are all connected to the above-mentioned zero-current overcurrent detection circuit.

[0013] Furthermore, the PLC control loop includes a main loop first contactor KM1, a main loop second contactor KM2, a main loop third contactor KM3, a main loop fourth contactor KM4, a first digital output relay KA1, a second digital output relay KA2, a third digital output relay KA3, a fourth digital output relay KA4, a fifth digital output relay KA5, a sixth digital output relay KA6, a seventh digital output relay KA7, an eighth digital output relay KA8, a ninth digital output relay KA9, a tenth digital output relay KA10, a first circuit breaker QF1, a second circuit breaker QF2, a third circuit breaker QF3, a fourth circuit breaker QF4, a fifth circuit breaker QF5, a sixth digital output relay KA6, a seventh digital output relay KA7, an eighth digital output relay KA8, a ninth digital output relay KA9, a tenth digital output relay KA10, a first circuit breaker QF1, a second circuit breaker QF2, a third circuit breaker QF3, a fourth circuit breaker QF4, a fifth circuit breaker QF5, a sixth Circuit breaker QF6, first reed switch relay KR1, second reed switch relay KR2, third reed switch relay KR3, fourth reed switch relay KR4, the closing command output of the first circuit breaker QF1 is connected to the normally open contact of the first digital output relay KA1, the opening command output of the first circuit breaker QF1 is connected to the normally open contact of the second digital output relay KA2, the closing command output of the second circuit breaker QF2 is connected to the normally open contact of the third digital output relay KA3, the opening command output of the second circuit breaker QF2 is connected to the normally open contact of the fourth digital output relay KA4, the closing command output of the third circuit breaker QF3 is connected to the normally open contact of the fifth digital output relay KA5, and the opening command output of the third circuit breaker QF3 is connected to the normally open contact of the sixth digital output relay KA6.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] When a certain section of the busbar of the utility model experiences a voltage "temporary sag" or power is withdrawn, another segmented power supply is quickly connected to reduce or avoid the impact of the voltage "temporary sag"; at the same time, it also solves the problem of a single busbar segmented power supply system, in which the equipment on the busbar needs to change the operating mode without stopping operation, and the problem of "loop-closing" operation is required. In addition, the PLC control system is used to transform the original manual division operation into "one-key operation", which not only saves operation time, but also simplifies the operation and avoids the possibility of misoperation.

[0016] The utility model adopts a group of quick-cut switches in the main switching circuit to switch between three circuit breakers for standby, thereby improving the utilization rate of the quick-cut switches and reducing the equipment manufacturing cost relative to connecting a group of quick-cut switches in parallel on each circuit breaker. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is a circuit diagram of the utility model. DETAILED DESCRIPTION

[0018] The utility model is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0019] like Figure 1 As shown, a single-bus segmented power supply system fast-cutting device includes a main switching circuit, a control power fast-cutting circuit, a voltage detection comparison circuit, a zero current overcurrent detection circuit and a PLC control circuit. The main switching circuit is used to provide fast bypass switching for the circuit breaker in standby mode. The voltage detection comparison circuit and the zero current overcurrent detection circuit connect the comparison detection logic signal to the PLC digital input point of the PLC control circuit. The PLC is used to output the detected voltage sag and the host computer instruction to the main switching circuit switching and the control power fast-cutting circuit power switching through the PLC digital output point.

[0020] Main switching circuit:

[0021] It includes a first circuit breaker QF1 connected to a first power supply, the first circuit breaker QF1 is connected to a first three-phase current transformer I1, the first three-phase current transformer I1 is connected to a bus terminal of a first distribution line, and also includes a second circuit breaker QF2 connected to a second power supply, the second circuit breaker QF2 is connected to a second three-phase current transformer I2, the second three-phase current transformer I2 is connected to a bus terminal of a second distribution line, a third circuit breaker QF3 is connected between the bus terminal of the first distribution line and the bus terminal of the second distribution line, and a bypass circuit is connected between the first power supply, the second power supply and both ends of the third circuit breaker QF3.

[0022] The bypass circuit includes a seventh circuit breaker QF7 connected to the first power supply, the seventh circuit breaker QF7 is connected to the normally open contact of the third contactor KM3 of the main circuit, the normally open contact of the third contactor KM3 of the main circuit is connected to the reactance L and the normally open contact of the second contactor KM2 of the main circuit, the normally open contact of the second contactor KM2 of the main circuit is connected to the bus terminal of the second-section distribution line, the other end of the reactance L is connected to the first thyristor V1 and the second thyristor V2 which are connected in reverse parallel, the gate switches of the first thyristor V1 and the second thyristor V2 are connected to the normally open contact of the first reed switch relay KR1, one end of the anode and cathode of the first thyristor V1 and the second thyristor V2 is connected to the normally open contact of the first contactor KM1 of the main circuit, and the other end of the normally open contact of the first contactor KM1 of the main circuit is connected to the bus terminal of the first-section distribution line.

[0023] The normally open contact of the fourth contactor KM4 of the main circuit is connected between the normally open contact of the first contactor KM1 of the main circuit and the anode and cathode of the first thyristor V1 and the second thyristor V2. The normally open contact of the fourth contactor KM4 of the main circuit is connected to the eighth circuit breaker QF8. The other end of the eighth circuit breaker QF8 is connected between the second power supply and the second circuit breaker QF2.

[0024] The electrical branch circuit can provide a fast closing branch circuit for the first circuit breaker QF1 and a fast closing branch circuit for the second circuit breaker QF1.

[0025] Control power supply fast switching circuit:

[0026] The invention comprises a fourth circuit breaker QF4 connected to the inlet end of the seventh circuit breaker QF7 and a fifth circuit breaker QF5 connected to the inlet end of the eighth circuit breaker QF8. The other end of the fourth circuit breaker QF4 is connected to a third thyristor V3 and a fourth thyristor V4 connected in reverse parallel. The gate switch between the third thyristor V3 and the fourth thyristor V4 is connected to a normally closed contact of a second reed switch relay KR2. The third thyristor V3 and the fourth thyristor V4 are connected to a section of a distribution line control power bus. The other end of the fifth circuit breaker QF5 is connected to a fifth thyristor V3 and a fourth thyristor V4 connected in reverse parallel. The fifth thyristor V5, the sixth thyristor V6, the gate switch between the fifth thyristor V5 and the sixth thyristor V6 is connected to the normally closed contact of the third reed switch relay KR2, the fifth thyristor V5 and the sixth thyristor V6 are connected to the two-section distribution line control power bus, the two-section distribution line control power bus is also connected to the sixth circuit breaker QF6, the other end of the sixth circuit breaker QF6 is connected to the seventh thyristor V7 and the eighth thyristor V8 in reverse parallel, the gate switch between the seventh thyristor V7 and the eighth thyristor V8 is connected to the normally open contact of the fourth reed switch relay KR4.

[0027] Voltage detection comparison circuit:

[0028] The two-incoming A-phase voltage measurement and control unit includes a first rectifier bridge UR1 and a second rectifier bridge UR2. One end of the AC input end of the first rectifier bridge UR1 is connected to a first resistor R1, and the first resistor R1 is connected to an LA1 terminal, which is connected to the A phase of the first power supply. The other end of the AC input end of the first rectifier bridge UR1 is connected to the N phase of the first power supply. The DC positive and negative terminals of the first rectifier bridge UR1 are connected in parallel with a first voltage-dividing resistor R2; one end of the AC input end of the second rectifier bridge UR2 is connected to a second resistor R4, and the second resistor R4 is connected to an LA2 terminal, which is connected to the A phase of the second power supply. The other end of the AC input end of the second rectifier bridge UR2 is connected to the N phase of the second power supply, and the DC positive and negative terminals of the second rectifier bridge UR2 are connected in parallel with a second voltage-dividing resistor R5; the positive pole of the DC end of the first rectifier bridge UR1 is connected to a first current-limiting resistor R3, and the other end of the first current-limiting resistor R3 is connected to an anode of a first optocoupler U1, and a cathode of the first optocoupler U1 is connected to a cathode of the first optocoupler U1. The positive electrode of the DC end of the second rectifier bridge UR2 is connected to the positive electrode of the DC end of the second rectifier bridge UR2, the positive electrode of the DC end of the second rectifier bridge UR2 is also connected to the second current limiting resistor R6, the other end of the second current limiting resistor R6 is connected to the anode of the second optocoupler U2, the cathode of the second optocoupler U2 and the positive electrode of the first voltage-dividing resistor R2 are connected to the third current limiting resistor R7, the other end of the third current limiting resistor R7 is connected to the cathode of the first voltage-regulating diode ZD1, the anode of the first voltage-regulating diode ZD1 is connected to the anode of the third optocoupler U3, the negative electrode of the third optocoupler U3 is connected to the negative electrode of the second voltage-dividing resistor R5, the positive electrode of the second voltage-dividing resistor R5 is connected to the fourth current limiting resistor R8, the fourth current limiting resistor R8 is connected to the cathode of the second voltage-regulating diode ZD2, the anode of the second voltage-regulating diode ZD2 is connected to the anode of the fourth optocoupler U4, the cathode of the fourth optocoupler U4 is connected to the negative electrode of the second voltage-dividing resistor R5, and the output ends of the first optocoupler U1, the second optocoupler U2, the third optocoupler U3, and the fourth optocoupler U4 are connected to the PLC control loop. The output switch of the first optocoupler U1 is connected to the digital input terminal "0.0" of the PLC control system; the output switch of the second optocoupler U2 is connected to the digital input terminal "0.1" of the PLC control system; the emitter output terminal of the third optocoupler U3 is connected to the common negative terminal of the PLC control system, and the collector output terminal of the third optocoupler U3 is connected to the digital input terminal of the PLC control system. The collector output terminal of the fourth optocoupler U4 is connected to the digital input terminal of the PLC control system, thereby completing the process of converting two AC currents into two 2-8ms square wave pulses connected to the PLC digital points.

[0029] The two-incoming B-phase voltage measurement and control unit and the two-incoming C-phase voltage measurement and control unit are the same as the two-incoming A-phase voltage measurement and control unit.

[0030] Zero current overcurrent detection circuit:

[0031] The third rectifier bridge UR3 is included, the DC output end of the third rectifier bridge UR3 is connected to the series-connected diodes D1, D2, D3, and D4, the cathode of the D4 diode is connected to the voltage sampling resistor R10, the other end of the voltage sampling resistor R10 is connected to the negative terminal of the DC output end of the third rectifier bridge UR3, the series-connected diodes are connected in parallel with a first non-polar capacitor C2 and a fifth current-limiting resistor R9, and the fifth current-limiting resistor R9 is connected to a fifth optical coupler U5; the voltage sampling resistor R10 is connected in parallel with a second non-polar capacitor C2, a second non-polar capacitor C3, and a fifth current-limiting resistor R9. One end of the capacitor C2 is connected to the sixth current limiting resistor R11, the sixth current limiting resistor R11 is connected to the sixth optocoupler U6, the sixth optocoupler U6 is connected to the third voltage zener diode ZD3, the third voltage zener diode ZD3 is connected to the other end of the second non-polar capacitor C2, the output ends of the fifth optocoupler U5 and the sixth optocoupler U6 are connected to the PLC control loop, the output end of the fifth optocoupler U5 is connected to the digital input terminal "1.5" of the PLC control system, and the output end of the sixth optocoupler U6 is connected to the digital input terminal "1.6" of the PLC control system.

[0032] The three phases of the first three-phase current transformer I1 and the three phases of the second three-phase current transformer I2 are all connected to the above-mentioned zero-current overcurrent detection circuit.

[0033] Control loop:

[0034] It includes a main circuit first contactor KM1, a main circuit second contactor KM2, a main circuit third contactor KM3, and a main circuit fourth contactor KM4 connected to the digital input terminal of the PLC control system, as well as a normally open contact of the main circuit first contactor KM1, a normally open contact of the main circuit second contactor KM2, a normally open contact of the main circuit third contactor KM3, and a normally open contact of the main circuit fourth contactor KM4, a first digital output relay KA1, a second digital output relay KA2, a third digital output relay KA3, a fourth digital output relay KA4, a fifth digital output relay KA5, a sixth digital output relay KA6, a seventh digital output relay KA7, an eighth digital output relay KA8, a ninth digital output relay KA9, a tenth digital output relay KA10, a first circuit breaker QF1 normally open contact, a second circuit breaker QF2 normally open contact, a third digital output relay KA10 normally open contact, a The normally open contact of circuit breaker QF3, the normally open contact of the fourth circuit breaker QF4, the normally open contact of the fifth circuit breaker QF5, the normally open contact of the sixth circuit breaker QF6, the first reed switch relay KR1, the second reed switch relay KR2, the third reed switch relay KR3, and the fourth reed switch relay KR4. The closing command output of the first circuit breaker QF1 is connected to the normally open contact of the first digital output relay KA1, the opening command output of the first circuit breaker QF1 is connected to the normally open contact of the second digital output relay KA2, the closing command output of the second circuit breaker QF2 is connected to the normally open contact of the third digital output relay KA3, the opening command output of the second circuit breaker QF2 is connected to the normally open contact of the fourth digital output relay KA4, the closing command output of the third circuit breaker QF3 is connected to the normally open contact of the fifth digital output relay KA5, and the opening command output of the third circuit breaker QF3 is connected to the normally open contact of the sixth digital output relay KA6. The first contactor KM1 of the main circuit is connected to the normally open contact of the seventh digital output relay KA7, the second contactor KM2 of the main circuit is connected to the normally open contact of the eighth digital output relay KA8, the third contactor KM3 of the main circuit is connected to the normally open contact of the ninth digital output relay KA9, and the fourth contactor KM4 of the main circuit is connected to the normally open contact of the tenth digital output relay KA10.

[0035] The working principle of the utility model is as follows:

[0036] Operation mode switching function:

[0037] In normal operation of the power distribution system, the first circuit breaker QF1 and the second circuit breaker QF2 are in the closed state, supplying power to the first distribution line and the second distribution line busbar respectively, and the third circuit breaker QF3 is in the open state.

[0038] In this state, the seventh circuit breaker QF7 and the eighth circuit breaker QF8 are closed respectively. When the PLC control system detects that the three-phase voltages of the two incoming lines are normal, the first circuit breaker QF1 and the second circuit breaker QF2 are in the closed state, and the third circuit breaker QF3 is in the open state, the PLC control system issues a command to close the first contactor KM1 of the main circuit and the second contactor KM2 of the main circuit, and the normally open contacts of the first contactor KM1 of the main circuit and the normally open contacts of the second contactor KM2 of the main circuit are closed.

[0039] When the operation mode needs to be changed, the PLC host system (or a hardware button is set at the input point of the PLC control system) can issue a one-key command of "cut off the first circuit breaker QF1 and close the third circuit breaker QF3". The coil of the second digital output relay KA2 at the PLC output point is energized, and the normally open contact of the second digital output relay KA2 is closed, that is, the command of cutting off the first circuit breaker QF1 is output, and the main contact of the first circuit breaker QF1 is converted from the on state to the off state, which generally takes less than 1ms. The normally open contact of the first circuit breaker QF1 is disconnected, and the PLC input digital point "0.0" receives the "first circuit breaker QF1" opening signal and the "first circuit breaker QF1" is turned off. When the three-phase current is , the PLC control system controls the coil of the first reed switch relay KR1 and the fifth digital output relay KA5 to be energized, and the normally open contact of the first reed switch relay KR1 is closed (lasting about 1ms), so that the first thyristor V1 and the second thyristor V2 connected in reverse parallel are turned on. In this way, the current passes through the first contactor KM1 of the main circuit, the main contact of the second contactor KM2 of the main circuit, the first thyristor V1 and the second thyristor V2 connected in reverse parallel, and the current limiting reactor L, completing the rapid power supply from the second bus to the first bus. After about 10ms, the normally open contact of the fifth digital output relay KA5 is closed, so that the third circuit breaker QF3 is closed.

[0040] After the PLC control system detects that the normally open point of the third circuit breaker QF3 is closed, the PLC control system de-energizes the coil of the first reed switch relay KR1, disconnects the normally open contact of the first reed switch relay KR1, and cuts off the reverse-parallel first thyristor V1 and the second thyristor V2. The PLC control system output de-energizes the eighth digital output relay KA8, disconnects the normally open contact of the eighth digital output relay KA8, and de-energizes the second contactor KM2 of the main circuit. The PLC control system output energizes the ninth digital output relay KA9, closes the normally open contact of the ninth digital output relay KA9, energizes the third contactor KM3 of the main circuit, and closes the normally open contact of the third contactor KM3 of the main circuit. In this way, the original operating mode is converted to the operating mode in which the main contacts of the second circuit breaker QF2 carry two busbars, and carry one busbar through the main contacts of the third circuit breaker QF3. At the same time, the reverse parallel connection of the first thyristor V1 and the second thyristor V2 is completed, and a fast closing branch is provided for the first circuit breaker QF1 through the seventh circuit breaker QF7, the third contactor KM3 of the main circuit, the current limiting reactor L, and the normally open contact branch of the first contactor KM1 of the main circuit.

[0041] When it is necessary to restore the original two-section busbar split operation, the PLC upper system or the hardware button set at the input point of the PLC control system can also issue a one-key operation instruction. The PLC system issues an instruction to cut off the third circuit breaker QF3 and close the first circuit breaker QF1 based on the logic. The PLC control system energizes the coil of the sixth digital output relay KA6 based on the logical output, closes the normally open contact of the sixth digital output relay KA6, and opens the third circuit breaker QF3. After the PLC control system detects that the normally open point of the third circuit breaker QF3 is disconnected, the PLC control system controls the coil of the first reed switch relay KR1 and the first digital output relay KA1 to be energized. After about 1ms, the normally open contact of the first reed switch relay KR1 closes, and the first thyristor V1 and the second thyristor V2 connected in reverse parallel are turned on. The first incoming power is connected through the seventh circuit breaker QF7, the third contactor KM3 contact of the main circuit, The first thyristor V1, the second thyristor V2, the current-limiting reactor L, and the first contactor KM1 of the main circuit connected in reverse parallel are connected to a section of busbar. After about 10ms, the normally open contact of the first digital output relay KA1 is closed, and the first circuit breaker QF1 is closed. After about 80ms, after the first circuit breaker QF1 is closed, the PLC control system controls the output to de-energize the coil of the first reed switch relay KR1 and the coil of the ninth digital output relay KA9. The normally open contact of the first reed switch relay KR1 is disconnected, so that the first thyristor V1 and the second thyristor V2 connected in reverse parallel are cut off, and then the normally open contact of the ninth digital output relay KA9 is disconnected, so that the third contactor KM3 of the main circuit is de-energized and disconnected, and then the PLC control system energizes the eighth digital output relay KA8, and the normally open contact of the eighth digital output relay KA8 is closed, so that the second contactor KM2 of the main circuit is energized, so that the electrical operation mode is switched back to: the two-section busbar is operated in sections, and the third circuit breaker QF3 is in hot standby state.

[0042] "Voltage sag" automatic quick switching function:

[0043] Detection of "voltage sag": As shown in the figure, in the incoming line voltage detection unit, the "LA1" to ground "N" voltage of the first incoming line A phase is connected, and a sawtooth pulse DC voltage with a continuous waveform is formed at both ends of the first voltage-dividing resistor R2 through the first resistor R1 and the first rectifier bridge UR1. This voltage passes through the third current-limiting resistor R7, the first voltage-stabilizing diode ZD1 and the input diode of the third optocoupler U3. When the fluctuating current of this loop reaches the action threshold current with the sawtooth pulse DC voltage, the output end of the third optocoupler U3 is turned on. Conversely, when the current is less than the action threshold current, the output end of the third optocoupler U3 is cut off. By reasonably selecting the branch component parameters, the third optocoupler U3 will appear in a working state in which the cut-off time plus the conduction time is equal to 10ms in every 10ms cycle. When the voltage remains basically unchanged at the rated voltage value, the cut-off time of the output end of the third optocoupler U3 will maintain the fixed cut-off time of the output according to the design requirements. When a "voltage sag" occurs in the first incoming line A phase, the pulse voltage amplitude is reduced, thereby causing the output end of the third optocoupler U3 to be cut off. The time becomes longer. When the lengthened time reaches the given time of the PLC control system, the "voltage sag" criterion condition of the first incoming line A phase is met, and the "LA2" to ground "N" voltage of the second incoming line A phase is connected at the same time. The "time change" detection is consistent with the principle and electrical parameters of the first incoming line voltage detection circuit. Therefore, when the two incoming line voltages are running at the rated voltage and the two power supplies have the same frequency and initial phase angle, the positive high potential of the first voltage-dividing resistor R2 and the second voltage-dividing resistor R5 should always be at the same potential. Therefore, under normal circumstances The output ends of the two detection first optocouplers U1 and the second optocoupler U2 are both in the cut-off state. Similarly, when a "voltage sag" occurs in the first incoming line A phase at this time, the pulse amplitude at both ends of the first voltage-dividing resistor R2 will decrease, so that a potential difference will appear between the positive high potential of the first voltage-dividing resistor R2 and the second voltage-dividing resistor R5. When the potential difference reaches a certain value, the input branch current of the second optocoupler U2 will reach the trigger threshold value, causing the output end of the second optocoupler U2 to be turned on, so that the second criterion condition for the "voltage sag" of the first incoming line A phase is met.

[0044] When the two criteria are met at the same time, the PLC control system will issue a command to energize the coils of the second reed switch relay KR2 and the fourth reed switch relay KR4, and the normally closed point of the reed switch relay KR2 triggered by the gates of the third thyristor V3 and the fourth thyristor V4 of the first section of the control power system will be disconnected, and the normally open point of the fourth reed switch relay KR4, which connects the first and second sections of the control power system, will be closed. Since the voltage of the second section control bus is higher than the voltage of the first section control bus, the third thyristor V3 and the fourth thyristor V4 of the first section of the incoming line are subjected to reverse voltage and are cut off. At the same time, the PLC control system will The current measurement and control unit of the C control system determines whether the current exceeds the given value of the overcurrent protection of the incoming circuit breaker by the current flowing through the voltage sampling resistor R10. If it exceeds, it enters the waiting period and stops executing the output instruction; if it does not exceed, the PLC simultaneously energizes the coil of the second digital output relay KA2, so that the first incoming circuit breaker QF1 of the main power distribution system is opened, which takes about 80ms (the main and auxiliary contacts of the circuit breaker take about 1ms from "closed to open", and the main circuit arcs and loses power for 1ms). The opening of the first circuit breaker QF1 is completed, the normally open point of the first circuit breaker QF1 is disconnected, and the digital input of the PLC control system is "0.0" point receives a logic change, the first circuit breaker QF1 disconnects and the first judgment criterion is established. After the first circuit breaker QF1 is disconnected, the three-phase currents of the first circuit breaker QF1 are all zero, and the A1 phase secondary side detection terminal A1 of the first current transformer I1 flows through the four diodes D1, D2, D3, D4, and the voltage sampling resistor R10 through the third bridge UR3, and the current is zero. Therefore, the output of the fifth optocoupler U5 is in the cut-off state. In this way, when it is monitored that the ABC three-phase currents of the first circuit breaker QF1 are all zero, the three-phase contacts of the first circuit breaker QF1 have been disconnected and the second judgment criterion is established. Only when both judgments are established, the PLC control system outputs the first reed switch relay KR1 coil to be energized and the fifth digital output relay KA5 coil to be energized, so that the gate of the first thyristor V1 and the second thyristor V2 The normally open point of the first reed switch relay KR1 is closed (the closing time of the reed switch relay is about 1ms), and the first thyristor V1 and the second thyristor V2 are turned on. The second section of the main circuit The line provides power to a section of busbar through the normally open main contact of the second contactor KM2 of the main circuit, the current limiting reactor L, and the normally open main contact of the first relay KM1 of the main circuit. After the normally open point of the fifth digital output relay KA5 is closed, it takes about 80ms for the main contact of the third circuit breaker QF3 to close and bypass the first thyristor V1 and the second thyristor V2 power supply branch that are quickly closed. After the auxiliary contact of the third circuit breaker QF3 is closed, the PLC control system outputs the first reed switch relay KR1 The coil loses power, the first thyristor V1 and the second thyristor V2 are cut off, the PLC control system makes the coil of the second contactor KM2 of the main circuit lose power, and then makes the coil of the third contactor KM3 of the main circuit energized, so that the first thyristor V1 and the second thyristor V2 of the reverse parallel connection pass through the seventh circuit breaker QF7, the contact of the third contactor KM3 of the main circuit, the current limiting reactor L, and the normally open contact branch of the first contactor KM1 of the main circuit, providing a fast closing branch for the first incoming circuit breaker QF1.

Claims

1. A single busbar segmented power supply system fast switching device, characterized by: It includes a main switching circuit, a control power fast-cut circuit, a voltage detection comparison circuit, a zero current overcurrent detection circuit and a PLC control circuit. The main switching circuit is used to provide fast bypass switching for the circuit breaker in standby mode. The voltage detection comparison circuit and the zero current overcurrent detection circuit connect the comparison detection logic signal to the PLC digital input point of the PLC control circuit. The PLC control circuit is used to output the detected voltage sag and the host computer instruction to the main switching circuit switching and the control power fast-cut circuit power switching through the PLC digital output point.

2. A single busbar segmented power supply system quick-cut device according to claim 1, characterized in that: The main switching circuit includes a first circuit breaker QF1 connected to the first power supply, the first circuit breaker QF1 is connected to the first three-phase current transformer I1, the first three-phase current transformer I1 is connected to the bus end of a first distribution line, and also includes a second circuit breaker QF2 connected to the second power supply, the second circuit breaker QF2 is connected to the second three-phase current transformer I2, the second three-phase current transformer I2 is connected to the bus end of the second distribution line, a third circuit breaker QF3 is connected between the bus end of the first distribution line and the bus end of the second distribution line, and a bypass circuit is connected between the first power supply, the second power supply and the two ends of the third circuit breaker QF3.

3. A single busbar segmented power supply system quick-cut device according to claim 2, characterized in that: The bypass circuit includes a seventh circuit breaker QF7 connected to the first power supply, the seventh circuit breaker QF7 is connected to the normally open contact of the third contactor KM3 of the main circuit, the normally open contact of the third contactor KM3 of the main circuit is connected to the reactor L and the normally open contact of the second contactor KM2 of the main circuit, the normally open contact of the second contactor KM2 of the main circuit is connected to the bus terminal of the second-stage distribution line, the other end of the reactor L is connected to the first thyristor V1 and the second thyristor V2 connected in reverse parallel, the gate switches of the first thyristor V1 and the second thyristor V2 are connected to the normally open contact of the first reed switch relay KR1, ... One end of the positive and negative poles of the thyristor V2 is connected to the normally open contact of the first contactor KM1 of the main circuit, and the other end of the normally open contact of the first contactor KM1 of the main circuit is connected to the busbar end of a section of the distribution line. The normally open contact of the fourth contactor KM4 of the main circuit is connected between the normally open contact of the first contactor KM1 of the main circuit and the positive and negative poles of the first thyristor V1 and the second thyristor V2. The normally open contact of the fourth contactor KM4 of the main circuit is connected to the eighth circuit breaker QF8, and the other end of the eighth circuit breaker QF8 is connected between the second power supply and the second circuit breaker QF2.

4. A single busbar segmented power supply system quick-cut device according to claim 3, characterized in that: The control power supply fast-cut circuit includes a fourth circuit breaker QF4 connected to the inlet end of the seventh circuit breaker QF7, and a fifth circuit breaker QF5 connected to the inlet end of the eighth circuit breaker QF8. The other end of the fourth circuit breaker QF4 is connected to the third thyristor V3 and the fourth thyristor V4 which are connected in reverse parallel. The gate switch between the third thyristor V3 and the fourth thyristor V4 is connected to the normally closed contact of the second reed switch relay KR2. The third thyristor V3 and the fourth thyristor V4 are connected to a section of the distribution line control power supply bus. The other end of the fifth circuit breaker QF5 is connected to the reverse parallel The fifth thyristor V5 and the sixth thyristor V6, the gate switch between the fifth thyristor V5 and the sixth thyristor V6 is connected to the normally closed contact of the third reed switch relay KR3, the fifth thyristor V5 and the sixth thyristor V6 are connected to the two-section distribution line control power bus, the two-section distribution line control power bus is also connected to the sixth circuit breaker QF6, the other end of the sixth circuit breaker QF6 is connected to the seventh thyristor V7 and the eighth thyristor V8 in reverse parallel, the gate switch between the seventh thyristor V7 and the eighth thyristor V8 is connected to the normally open contact of the fourth reed switch relay KR4.

5. A single busbar segmented power supply system quick-cut device according to claim 4, characterized in that: The voltage detection comparison loop includes a first rectifier bridge UR1 and a second rectifier bridge UR2. One end of the AC input end of the first rectifier bridge UR1 is connected to a first resistor R1, and the first resistor R1 is connected to a LA1 terminal, which is connected to a first power supply. The other end of the AC input end of the first rectifier bridge UR1 is connected to the N phase of the first power supply. The DC positive and negative terminals of the first rectifier bridge UR1 are connected in parallel with a first voltage-dividing resistor R2; one end of the AC input end of the second rectifier bridge UR2 is connected to a second resistor R4, and the second resistor R4 is connected to a LA2 terminal, which is connected to the second power supply. The other end of the AC input end of the second rectifier bridge UR2 is connected to the N phase of the second power supply. The DC positive and negative terminals of the second rectifier bridge UR2 are connected in parallel with a second voltage-dividing resistor R5; the positive pole of the DC end of the first rectifier bridge UR1 is connected to a first current-limiting resistor R3, and the other end of the first current-limiting resistor R3 is connected to an anode of a first optocoupler U1, and a cathode of the first optocoupler U1 is connected to a cathode of the first optocoupler U1. The positive pole of the DC end of the second rectifier bridge UR2 is connected, and the positive pole of the DC end of the second rectifier bridge UR2 is also connected to the second current limiting resistor R6, the other end of the second current limiting resistor R6 is connected to the anode of the second optocoupler U2, the cathode of the second optocoupler U2 and the positive pole of the first voltage-dividing resistor R2 are connected to the third current limiting resistor R7, the other end of the third current limiting resistor R7 is connected to the cathode of the first voltage-limiting diode ZD1, the anode of the first voltage-limiting diode ZD1 is connected to the anode of the third optocoupler U3, the negative pole of the third optocoupler U3 is connected to the negative pole of the second voltage-dividing resistor R5, the positive pole of the second voltage-dividing resistor R5 is connected to the fourth current limiting resistor R8, the fourth current limiting resistor R8 is connected to the cathode of the second voltage-limiting diode ZD2, the anode of the second voltage-limiting diode ZD2 is connected to the anode of the fourth optocoupler U4, the cathode of the fourth optocoupler U4 is connected to the negative pole of the second voltage-dividing resistor R5, and the output ends of the first optocoupler U1, the second optocoupler U2, the third optocoupler U3, and the fourth optocoupler U4 are connected to the PLC control loop.

6. A single busbar segmented power supply system quick-cut device according to claim 5, characterized in that: The zero current overcurrent detection circuit includes a third rectifier bridge UR3, the DC output end of the third rectifier bridge UR3 is connected to the series-connected diodes D1, D2, D3, and D4, the cathode of the D4 diode is connected to the voltage sampling resistor R10, the other end of the voltage sampling resistor R10 is connected to the negative terminal of the DC output end of the third rectifier bridge UR3, the series-connected diodes are connected in parallel with the first non-polar capacitor C2 and the fifth current limiting resistor R9, and the fifth current limiting resistor R9 is connected to the fifth optical coupler U5; the voltage sampling resistor R10 is connected in parallel with the second non-polar capacitor C2, one end of the second non-polar capacitor C2 is connected to the sixth current limiting resistor R11, the sixth current limiting resistor R11 is connected to the sixth optical coupler U6, the sixth optical coupler U6 is connected to the third voltage zener diode ZD3, the third voltage zener diode ZD3 is connected to the other end of the second non-polar capacitor C2, and the output ends of the fifth optical coupler U5 and the sixth optical coupler U6 are connected to the PLC control loop.

7. A single busbar sectionalized power supply system quick-cut device according to claim 6, characterized in that: The three phases of the first three-phase current transformer I1 and the three phases of the second three-phase current transformer I2 are all connected to the zero-current overcurrent detection circuit.

8. A single busbar segmented power supply system quick-cut device according to claim 1 or 7, characterized in that: The PLC control loop includes a main loop first contactor KM1 connected to the PLC control system, a main loop second contactor KM2, a main loop third contactor KM3, a main loop fourth contactor KM4, a first digital output relay KA1, a second digital output relay KA2, a third digital output relay KA3, a fourth digital output relay KA4, a fifth digital output relay KA5, a sixth digital output relay KA6, a seventh digital output relay KA7, an eighth digital output relay KA8, a ninth digital output relay KA9, a tenth digital output relay KA10, a first circuit breaker QF1, a second circuit breaker QF2, a third circuit breaker QF3, a fourth circuit breaker QF4, a fifth circuit breaker QF5, a sixth circuit breaker Device QF6, the first reed switch relay KR1, the second reed switch relay KR2, the third reed switch relay KR3, and the fourth reed switch relay KR4. The closing command output of the first circuit breaker QF1 is connected to the normally open contact of the first digital output relay KA1, the opening command output of the first circuit breaker QF1 is connected to the normally open contact of the second digital output relay KA2, the closing command output of the second circuit breaker QF2 is connected to the normally open contact of the third digital output relay KA3, the opening command output of the second circuit breaker QF2 is connected to the normally open contact of the fourth digital output relay KA4, the closing command output of the third circuit breaker QF3 is connected to the normally open contact of the fifth digital output relay KA5, and the opening command output of the third circuit breaker QF3 is connected to the normally open contact of the sixth digital output relay KA6.

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