A fast phase commutation method for low-voltage distribution network based on magnetic latching relay

Abstract

The invention discloses a fast commutation method for a low-voltage distribution network based on a magnetic latching relay, using a magnetic latching relay as a commutation switch, combining the AC zero-crossing detection signal and the status feedback signal of the commutation switch, and using a sequential logic control algorithm to complete the load. Switching of phase sequence. By improving the control method of the magnetic latching relay, the present invention greatly shortens the power-off time during the commutation process, and the longest power-off time is about 15ms, which does not affect the normal power consumption of household user loads, and satisfies the principle of AC zero-crossing switching , the error is small, no arc will be generated, and the appropriate verification time is set by using the state feedback signal of the commutation switch to judge whether the cut-off and cut-in are successful, which can avoid short-circuit between phases and ensure the normal operation of the low-voltage distribution network .

Description

technical field [0001] The invention relates to the field of power system distribution network automation and control, in particular to a low-voltage distribution network fast phase commutation method based on a magnetic latching relay. Background technique [0002] my country's low-voltage distribution network mainly adopts a three-phase four-wire system. Ideally, the three-phase load is a balanced configuration. In fact, due to the access of high-power single-phase loads and differences in user habits of electricity, it is often easy to cause the end of the distribution network to The voltage is lower than the limit value, which aggravates the three-phase imbalance problem and greatly increases the power loss. The intelligent phase selection switch is the first recommended method to control the three-phase unbalance in the "Notice on Carrying out the Governance of Three-phase Load Unbalance in Distribution Areas" by the Ministry of Transport and Inspection of the State Grid...

AI Technical Summary

Problems solved by technology

However, during the load commutation process performed by the terminal commutation switch, it is very easy to affect the normal power consumption of the load. This paper studies the new method of fast commutation in low-voltage distribution network to solve this problem.

[0003] The previous commutation switch mainly composed of relays has a simple drive circuit, strong overcurrent and overvoltage capacity, and strong anti-interference ability. However, the traditional control method takes a long commutation time, exceeding 20ms, which affects electrical equipment. The continuous power supply, and the relay immediately performs the breaking task after receiving the switching command. At this time, it is very likely that the voltage or current passing through the relay is at the maximum value, and the arcing phenomenon is likely to occur, which does not meet the AC requirements. The principle of zero-crossing switching (refers to the principle of putting into the circuit and cutting out the circuit when the AC voltage and current are just at the zero point), which will affect the normal operation and life of the relay, and more serious consequences may be due to the contact of the relay. Burning so that the relay cannot be disconnected, resulting in a short circuit between phases

Therefore, it is urgent to solve the problems of long commutation time and unsafe commutation of the commutation method based on magnetic latching relays.

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