Double-loop mutual switching device for preventing converter power supply system from voltage sag

Abstract

The invention discloses a double-loop mutual switching device for avoiding power interference of a converter power supply system. According to the working principle of double-loop power supply mutual switching, a first power supply is sent to a mother board through a circuit breaker Q1, a second power supply is sent to the mother board through the circuit breaker Q1, Q1 is a working power supply, Q2 is a standby power supply, only one of the two power supplies works, and when the first power supply loses power, the circuit breaker Q1 trips automatically; and then the circuit breaker Q2 is automatically switched on, so that the purpose of continuous power supply of the mother board power supply is achieved. According to the design, the problem of mis-tripping of an original system under the condition of system voltage fluctuation is mainly solved, the design idea is that when the system voltage is instantaneously reduced, tripping signals are sent out in a delayed mode, so that the system can avoid the moment of voltage fluctuation, a main element is a capacitor, and the function is achieved through the characteristics of the capacitor.

Description

Technical Field

[0001] The invention relates to a double-circuit mutual switching device for preventing power shaking of a converter power supply system. Background Art

[0002] The power supply system of the No. 2 converter of the No. 1 Steel Plant of Bayi Iron and Steel Co., Ltd. adopts a dual-circuit power supply, one circuit is taken from the N30 transformer as the working power supply, and the other circuit is taken from the N31 transformer as the backup power supply. In order to ensure the continuity of smelting, the power supply stability of the converter is required to be high. Generally, the dual-circuit mutual throwing method is often adopted, that is, the pressure loss coil of the circuit breaker is used to detect the current power supply voltage. When the power supply voltage is less than 15% of the rated voltage (AC 380V), the working circuit breaker is disconnected, and then the backup power circuit breaker is automatically closed, thereby ensuring the continuity of power supply. However, the power grid of Bayi Iron and Steel Co., Ltd. is not stable enough, and when other users on the power grid fail, it will also cause the voltage of the power grid to fluctuate instantly, commonly known as shaking. At this time, the above system will act immediately. When the circuit breaker is instantly mutual thrown, the system will have a momentary power interruption, causing the equipment under the system such as the inverter alarm, contactor release, PLC stop running, etc., and then cause the entire system to stop working.

[0003] The purpose of the present invention is to provide a dual-circuit mutual switching device for avoiding power fluctuations in the converter power supply system, mainly to solve the problem of false tripping of the original system under the condition of system voltage fluctuations. When the system voltage drops instantaneously, the trip signal is delayed, so that the system can avoid the moment of voltage fluctuation. Summary of the invention

[0004] The technical solution adopted by the present invention is a double-circuit mutual switching device for avoiding power swing in the converter power supply system. Closing coils 1XF and 2XF of the circuit breaker and opening coils 1MX and 2MX of the circuit breaker are respectively installed in the double-circuit circuit; the opening coils 1MX and 2MX are respectively powered by DC 110V; in the double-circuit circuit, D1, D2, D3, and D4 are diodes, C1, C2, C3, and C4 are electrolytic capacitors, D1, D3, and C2 form a single-phase half-wave rectifier circuit, which is used for the opening circuit of power supply No. 2, and D2, D4, and C1 form a single-phase half-wave rectifier circuit. Phase half-wave rectification circuit is used for the disconnection circuit of power supply No. 1; 1T and 2T are AC transformers, which convert AC 220V into AC 20V; KBP308 is a single-phase full-wave rectifier bridge, which rectifies AC 20V into DC 19V, which is used to charge capacitors C3 and C4; K1 and K2 are DC 24V intermediate relays, and the auxiliary contacts of K1 and K2 realize mutual switching in automatic state; SK is a selection switch, which is used for manual and automatic switching of the device. When manual is selected, all circuit breakers are manually operated, and when automatic is selected, the device realizes automatic mutual switching.

[0005] The working principle of the device: When the selector switch is set to automatic, power supply No. 1 is the working power supply, circuit breaker Q1 is in the closed state, and circuit breaker Q2 is in the open state: When the working power supply voltage is instantly lower than 185V, the original system circuit breaker will immediately trip and automatically switch to the backup power supply, while the new device will not trip immediately at this time, because capacitor C3 stores electrical energy, and C3 and 1K form a circuit, so that 1K is kept for 2~3.5 seconds without releasing, thereby avoiding this momentary low voltage. When the working power supply is lost, C3 discharges to 1K, and when the voltage across C3 is lower than 25% (18V) of the rated voltage of the intermediate relay 1K, 1K is released. At this time, the normally closed auxiliary contact of 1K, the opening coil 1MX and capacitor C1 form a circuit, and the opening coil 1MX is energized and works through the electrical energy of capacitor C1, thereby tripping the circuit breaker Q1. When the circuit breaker Q1 trips, the other normally closed auxiliary contact of 1K, the closing coil 2XF and the switch B2 form a circuit, thereby completing the automatic closing of the circuit breaker Q2. When the power supply No. 2 is the working power supply, the working principle is the same, and the action sequence is reversed. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a schematic diagram of the circuit connection structure of the present invention. Implementation

[0007] A double-circuit switching device for preventing power fluctuations in the converter power supply system, such as Figure 1 As shown, the closing coils 1XF and 2XF of the circuit breaker and the opening coils 1MX and 2MX of the circuit breaker are installed in the double-circuit circuit respectively; the opening coils 1MX and 2MX are powered by DC 110V respectively; in the double-circuit circuit, D1, D2, D3, and D4 are diodes, C1, C2, C3, and C4 are electrolytic capacitors, D1, D3, and C2 form a single-phase half-wave rectifier circuit for the opening circuit of power supply No. 2, and D2, D4, and C1 form a single-phase half-wave rectifier circuit for the opening circuit of power supply No. 1; 1T and 2T are AC transformers, which convert AC 220V into AC 20V, KBP308 is a single-phase full-wave rectifier bridge, which rectifies AC 20V into DC 19V, and is used to charge capacitors C3 and C4. K1 and K2 are DC 24V intermediate relays, and the auxiliary contacts of K1 and K2 realize mutual switching in automatic state; SK is a selection switch, which is used to switch the device between manual and automatic. When manual is selected, all circuit breakers are manually operated, and when automatic is selected, the device realizes automatic mutual switching.

Claims

1. A double-circuit switching device for preventing power swing in the converter power supply system, characterized in that The double-circuit circuit is equipped with closing coils 1XF and 2XF of the circuit breaker, and opening coils 1MX and 2MX of the circuit breaker; the opening coils 1MX and 2MX are powered by DC 110V respectively; in the double-circuit circuit, D1, D2, D3, and D4 are diodes, C1, C2, C3, and C4 are electrolytic capacitors, D1, D3, and C2 form a single-phase half-wave rectifier circuit for the opening circuit of power supply No. 2, and D2, D4, and C1 form a single-phase half-wave rectifier circuit for the opening circuit of power supply No. 1; 1T and 2T are AC transformers, which convert AC 220V into AC 20V, KBP308 is a single-phase full-wave rectifier bridge, which rectifies AC 20V into DC 19V, and is used to charge capacitors C3 and C4. K1 and K2 are DC 24V intermediate relays, and the auxiliary contacts of K1 and K2 realize mutual switching in automatic state; SK is a selection switch, which is used to switch the device between manual and automatic. When manual is selected, all circuit breakers are manually operated, and when automatic is selected, the device realizes automatic mutual switching.

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