Power connection device

Abstract

The invention provides a power supply connection device which is composed of a 1 # power supply incoming line circuit breaker QF1, a 2 # power supply incoming line circuit breaker QF2, a connection circuit breaker MCB, a connection isolation MDB and a current limiting reactor L. The power supply connection device is used for solving the problem of loop closing power regulation under the scene that the voltage amplitude and phase angle difference of a power grid bus is large. According to the device, by tracking the frequency difference and angle difference changes of two paths of power supply voltages in real time, loop closing operation is carried out when voltage vector phases coincide, and equipment overload and relay protection maloperation caused by overlarge loop closing current are avoided. The device further comprises a current limiting reactor which is used for stabilizing impact current in the loop closing transient process and limiting short-circuit current when a short-circuit fault occurs. The power supply reliability can be effectively improved, and risks in loop closing operation are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, belonging to the category of power supply connection in the closed-loop power adjustment operation of power grids, and particularly relates to a power supply connection device. Background Art

[0002] In power grids, considering the impact of short-circuit current on the operation of the system and equipment, closed-loop design and open-loop operation are generally implemented. When a certain bus, switch, or feeder needs to be repaired or fails, the load supplied by multiple power sources on this bus, switch, or feeder can be load transferred. Through closed-loop operation, the load is transferred to other connected buses or feeders, thereby achieving load transfer without power interruption, that is, closed-loop power adjustment. Closed-loop power adjustment can reduce the power outage time of users, improve the reliability of power supply, ensure the power supply quality of the system, and improve the public's satisfaction with power services. With the increase in power load density and the complexity of the grid structure, dual-power supply or even multi-power supply is becoming more and more common. It has become an inevitable trend to achieve load transfer without power interruption through closed-loop and open-loop operations. When closed-loop power adjustment is carried out between substations belonging to two different partitions, affected by the system operation status and grid parameters, risks such as equipment overload, maloperation of relay protection, excessive short-circuit current, and accident expansion caused by electromagnetic loop network may occur. That is, the main problem brought by closed-loop operation is that there is a certain voltage phasor difference between the two busbars on both sides of the closed-loop switch or tie switch before closing the loop, which may lead to excessive closed-loop current during the closed-loop operation, causing maloperation of instantaneous protection or overcurrent protection, expanding the power outage area, and resulting in serious consequences. Summary of the Invention

[0003] To solve the problems of closed-loop power adjustment in the scenario where the voltage amplitudes and phase angles of power grid busbars are quite different, which causes economic and social impacts caused by short-term power outages and poor power supply reliability, the present application provides a power supply connection device, which consists of a No. 1 power supply incoming breaker, a No. 2 power supply incoming breaker, a tie breaker, a tie isolation, and a current-limiting reactor. It is characterized in that: the incoming end of the No. 1 power supply incoming breaker is connected to Power Supply I through a No. 1 current transformer, the outgoing end of the No. 1 power supply incoming breaker is connected to the tie breaker through Section I busbar, the incoming end of the No. 2 power supply incoming breaker is connected to Power Supply II through a No. 2 current transformer, the outgoing end of the No. 2 power supply incoming breaker is connected to the tie isolation through Section II busbar, a current-limiting reactor is connected in series between the tie breaker and the tie isolation, a No. 1 line voltage transformer is connected to Power Supply I, and a No. 2 line voltage transformer is connected to Power Supply II; When the power supply connection device of the present application performs active closed-loop power adjustment, it includes the following steps: Collect the voltage signals U1 and U2 of the line voltage transformer of Line 1 and the line voltage transformer of Line 2, track the frequency difference and phase difference changes of the voltage in real time, calculate the next phase coincidence time when the two power supply voltage vectors coincide in phase for the first time in the feedback, subtract the inherent closing time of the tie breaker before the next phase coincidence, and send a closing signal to the tie breaker to ensure that the tie breaker is closed exactly when the two power supply voltage vectors coincide in phase; The power transfer of a power supply connection device in case of a power supply failure in this application includes the following steps: When a power supply in use fails, trip the power supply incoming breaker on the faulty side, and then collect the voltage signals U1 and U2 of the line voltage transformer of Line 1 and the line voltage transformer of Line 2, track the frequency difference and phase difference changes of the voltage in real time, calculate the next phase coincidence time when the two power supply voltage vectors coincide in phase for the first time in the feedback, subtract the inherent closing time of the tie breaker before the next phase coincidence, and send a closing signal to the tie breaker When the I-section bus and the II-section bus are operating in parallel and exceed the preset capacity of the operating power supply, quickly execute the load shedding program, and the load shedding sequence is: the breaker of the tertiary load feeder on the faulty section - the breaker of the tertiary load feeder on the non-faulty section - the breaker of the secondary load feeder on the faulty section - the breaker of the secondary load feeder on the non-faulty section.

[0004] When the negative sequence voltage is higher than 8V, or the positive sequence voltage is lower than 30V and the voltage is greater than the energized threshold at the same time, and any one of the two criteria is met, the device determines that the PT is disconnected after a 5S delay; after the PT is disconnected, if the voltage recovers and no longer meets the above conditions, it returns instantaneously; the PT disconnection alarm can block all switching protections.

[0005] When the following conditions are detected, the controller is blocked: a) The switch position is abnormal (the incoming line 1, incoming line 2 switches, and tie switch are all in the closed position or all in the open position, and a blocking signal is sent after a 30S delay; a blocking signal is sent after a 0.5S delay when the PT disconnecting switch is not closed); b) The backup power supply is lost and blocked; c) The PT disconnection is blocked; d) The protection is blocked.

[0006] When the operating power supply is switched to the faulty bus, quickly trip the tie breaker.

[0007] When the bus voltage is lower than the setting voltage and reaches the setting delay, the device starts automatically and performs switching in the automatic mode.

[0008] When the working power supply breaker trips accidentally, the device is started by the auxiliary contact of the working switch, and the tie breaker is closed when the switching conditions are met.

[0009] The current-limiting reactor is configured to suppress the impact current during the closed-loop transient process, and the current-limiting reactor is also configured to limit the short-circuit current and protect the primary equipment during a short-circuit fault in the closed-loop operation. Description of the Drawings

[0010] Figure 1 This is the primary wiring schematic diagram of this application. Specific implementation manners

[0011] A power connection device provided by the present invention includes a No. 1 power incoming line breaker QF1, a No. 2 power incoming line breaker QF2, a tie breaker MCB, a tie isolation MDB, and a current limiting reactor L. It is characterized in that: the incoming line end of the No. 1 power incoming line breaker QF1 is connected to the power supply I through a No. 1 current transformer CT1, the outgoing line end of the No. 1 power incoming line breaker QF1 is connected to the tie breaker MCB through the I-section busbar, the incoming line end of the No. 2 power incoming line breaker QF2 is connected to the power supply II through a No. 2 current transformer CT2, the outgoing line end of the No. 2 power incoming line breaker QF2 is connected to the tie isolation MDB through the II-section busbar, a current limiting reactor L is connected in series between the tie breaker MCB and the tie isolation MDB, a No. 1 line voltage transformer PT1 is connected to the power supply I, and a No. 2 line voltage transformer PT2 is connected to the power supply II; The current limiting reactor L is connected in series between the tie breaker MCB and the tie isolation MDB, and is used for suppressing the impact current during the closed-loop transient process and limiting the short-circuit current during the short-circuit fault in the closed-loop operation to protect the primary equipment; The No. 1 line voltage transformer PT1 is connected to the power supply I and is used for collecting the voltage signal of the power supply I; The No. 2 line voltage transformer PT2 is connected to the power supply II and is used for collecting the voltage signal of the power supply II.

[0012] The working steps of a power connection device applied for in the present invention are as follows: S1. Actively close the loop and adjust the power: - Collect the voltage signals U1 and U2 of the No. 1 line voltage transformer PT1 and the No. 2 line voltage transformer PT2, and track the frequency difference and phase difference changes of the voltage in real time; - When the two power supply voltage vectors first coincide in phase, calculate the next phase coincidence time; - Subtract the inherent closing time of the tie breaker MCB before the next phase coincidence, and send a closing signal to the tie breaker MCB to ensure that the tie breaker MCB closes exactly when the two power supply voltage vectors coincide in phase.

[0013] S2. Adjust the power when there is a power supply fault: - When a fault occurs in the in-use power supply, trip the power incoming line breaker on the faulty side; - Collect the voltage signals U1 and U2 of the No. 1 line voltage transformer PT1 and the No. 2 line voltage transformer PT2, and track the frequency difference and phase difference changes of the voltage in real time; - When the phase of the two power supply voltage vectors in the feedback coincides for the first time, calculate the time of the next phase coincidence; - Subtract the inherent closing time of the tie breaker MCB before the next phase coincidence and send a closing signal to the tie breaker MCB.

[0014] S3. Load shedding procedure: - When the I-section bus and the II-section bus are operating in parallel and exceed the preset capacity of the operating power supply, quickly execute the load shedding procedure; - The load shedding sequence is: the breaker of the tertiary load feeder in the faulty section → the breaker of the tertiary load feeder in the non-faulty section → the breaker of the secondary load feeder in the faulty section → the breaker of the secondary load feeder in the non-faulty section.

[0015] S4. PT disconnection detection: - When the negative sequence voltage is higher than 8V, or the positive sequence voltage is lower than 30V and the voltage is greater than the energized threshold at the same time, the device determines that the PT is disconnected after a 5S delay; - After the PT is disconnected, if the voltage recovers and no longer meets the above conditions, it returns instantaneously; - The PT disconnection alarm can block all switching protections.

[0016] S5. Controller blocking conditions: - Abnormal switch position (the 1# power incoming breaker QF1, the 2# power incoming breaker QF2, and the tie breaker MCB are all in the closed position or all in the open position; the tie isolation MDB is in the open position, and a blocking signal is sent after a 30S delay; if the PT disconnecting switch is not closed, a blocking signal is sent after a 0.5S delay); - Backup power loss blocking; - PT disconnection blocking; - Protection blocking; S6. Error correction function: - When the operating power supply is switched to the faulty bus, quickly trip the tie breaker MCB.

[0017] S7. Treatment of low bus voltage: - When the bus voltage is lower than the setting voltage and reaches the setting delay, the device starts by itself and performs switching in the automatic mode.

[0018] S8. Treatment of the theft tripping of the working power breaker: - When the working power breaker trips due to theft, the device is started by the auxiliary contact of the working switch, and the tie breaker MCB is closed when the switching conditions are met.

[0019] The faults of the in-use power supply include: voltage loss, phase loss, low voltage, overvoltage, excessive harmonic components, and frequency deviation.

[0020] When the associated circuit breaker (MCB) is replaced, overhauled, or reaches the specified operating time, more than one detection of the inherent closing time of the circuit breaker shall be carried out. The detection results are recorded in the device controller database, and the information on the inherent closing time of the associated circuit breaker in the database is updated.

Claims

1. A power supply connection device, comprising 1# power supply incoming line circuit breaker QF1, 2# power supply incoming line circuit breaker QF2, connection circuit breaker MCB, connection isolation MDB and current limiting reactor L, characterized in that: The incoming end of the 1# power incoming line circuit breaker QF1 is connected to the power source I via the 1# current transformer CT1, the outgoing end of the 1# power incoming line circuit breaker QF1 is connected to the connecting circuit breaker MCB via the I section bus, the incoming end of the 2# power incoming line circuit breaker QF2 is connected to the power source II via the 2# current transformer CT2, the outgoing end of the 2# power incoming line circuit breaker QF2 is connected to the connecting isolation MDB via the II section bus, a current limiting reactor L is connected in series between the connecting circuit breaker MCB and the connecting isolation MDB, the 1# line voltage transformer PT1 is connected to the power source I, and the 2# line voltage transformer PT2 is connected to the power source II; The present invention applies for a power connection device with the following working steps: S1. Active closing loop power regulation: - Collect the voltage signals U1 and U2 of the 1# line voltage transformer PT1 and the 2# line voltage transformer PT2, and track the frequency difference and angle difference of the voltage in real time. - When the two power supply voltage vectors overlap for the first time, calculate the next phase overlap time. - Subtract the inherent closing time of the tie circuit breaker MCB before the next phase coincidence, and send a closing signal to the tie circuit breaker MCB to ensure that the two power supply voltage vectors coincide with each other when the tie circuit breaker MCB is closed; S2. Power adjustment in case of power failure: - When the power supply fails, the circuit breaker of the power supply on the fault side will be tripped. - Collect the voltage signals U1 and U2 of the 1# line voltage transformer PT1 and the 2# line voltage transformer PT2, and track the frequency difference and angle difference of the voltage in real time. - When the two power supply voltage vectors overlap for the first time, calculate the next phase overlap time. - Subtract the inherent closing time of the tie circuit breaker MCB before the next phase coincidence, and send a closing signal to the tie circuit breaker MCB; S3. Load reduction procedure: - When busbars I and II are running in parallel and the preset capacity of the operating power is exceeded, the load shedding procedure is executed quickly. S4. PT disconnection detection: - When the negative sequence voltage is higher than 8V, or the positive sequence voltage is lower than 30V and the voltage is greater than the voltage threshold, the device will judge it as PT disconnection after a 5S delay. - After the PT is disconnected, if the voltage is restored and the above conditions are no longer met, it will return instantly. - PT disconnection alarm can lock all switching protections; S5. Controller lockout conditions: - Abnormal switch position, - Backup power failure lockout, - PT disconnection lockout, - Protective locking; S6. Error correction: - When the operating power is switched to the faulty bus, the interconnecting circuit breaker MCB is accelerated to open.

2. A power connection device according to claim 1, characterized in that: The current limiting reactor L is connected in series between the connecting circuit breaker MCB and the connecting isolator MDB, and is used to smooth the impact current of the closing loop transient process, and limit the short-circuit current when a short-circuit fault occurs during the closing loop operation, so as to protect the primary equipment.

3. A power connection device according to claim 1, characterized in that: The 1# line voltage transformer PT1 is connected to the power supply I and is used to collect the voltage signal of the power supply I; The 2# line voltage transformer PT2 is connected to the power supply II and is used to collect the voltage signal of the power supply II.

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