Driving circuit of bidirectional thyristor in composite switch, three-phase intelligent commutation system and commutation method

Abstract

The invention discloses a driving circuit of a bidirectional thyristor in a composite switch, a three-phase intelligent commutation system and a commutation method. The driving circuit comprises parallel capacitors at two ends of the bidirectional thyristor, wherein the bidirectional thyristor is connected in series with a resistor and a parallel branch of a normally-open relay and then is accessed to a A-phase, B-phase or C-phase circuit, and a piezoresistor is connected in series between the A-, B and C-phase circuit and a null line and among the A-phase circuit, the B-phase circuit and theC-phase circuit. By the driving circuit, the working reliability of the circuit is ensured, and false triggering of a main circuit of the thyristor is prevented; the resistor is connected in series with the main circuit, interphase large current short circuit probably occurring in two phases is prevented, the resistor is circuit-shorted during the commutation process, the large-current commutationprocess cannot be affected, the reliability of the commutation circuit is improved, and meanwhile, the probability of a fault occurring in a power distribution network system is prevented; and with the adoption of a low-voltage and low-power trigger driving circuit, driving triggering is reliable, the output voltage waveform distortion is small during the commutation process, and the influence ona user is small.

Description

technical field [0001] The invention belongs to the technical field of three-phase unbalanced automatic commutation adjustment, and in particular relates to a driving circuit of a bidirectional thyristor in a composite switch, a three-phase intelligent commutation system and a commutation method. Background technique [0002] In the low-voltage distribution network system, there are a large number of single-phase, asymmetrical, nonlinear, and impact loads. These loads change randomly and at different times, causing serious three-phase unbalance in the distribution system. The three-phase unbalance has great harm to the stable operation of the power grid, which leads to the unbalance of the three-phase current in the power supply system and affects the quality of power supply. At the same time, the three-phase imbalance will cause the neutral line to generate current. Since the neutral line is relatively thin, the line resistance and line inductance are large, which increases...

AI Technical Summary

Problems solved by technology

Three-phase unbalance is very harmful to the stable operation of the power grid, which leads to the unbalance of three-phase current in the power supply system and affects the quality of power supply.

[0010] Although this technology reduces the inrush current to a certain extent, reduces the failure rate, and improves the reliability of the thyristor trigger, but the overvoltage interference is not completely eliminated at the moment of power-on, and there is still a large inrush current at the moment of conduction, which damages the thyristor.

Although this process takes a short time, there are great hidden dangers in long-term frequent applications, and there are still certain problems in the reliability of thyristor triggering.

[0011] In the low-voltage distribution network with complex harmonics, because the voltage waveform seriously deviates from the sine wave and the du / dt is large, the thyristors in the system are susceptible to interference, resulting in false triggering, resulting in two-phase short circuit, excessive inrush current, and thyristors. Damaged and reduced reliability, seriously affecting the safe and stable operation of the power grid

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