Design And R&D Of Static Transfer Switch Controller

In recent years, for high and new-tech equipment, power quality has been required to behigher and more complete.In order to deal with comprehensive management of ship powersystem,more and more domestic and foreign experts and scholars begin to pay attention toand study the double power supply system.Static transfer switch (STS) is a system thatfunctions to switch power supply. With the device, normally, load is supported by mainpower; in case that fault of voltage occurs on main power, standby power will be switchedto automatically and quickly. The system provides an economic and effective solution forimproving power quality, and meets severe requirements of high and new-tech equipmentfor power quality.In the paper, based on introduction to basic principle of STS and analysis onnon-auxiliary convertor circuit, forced convertor circuit and a few LC auxiliary resonantconvertor circuits, a new LC bridge-type auxiliary resonant convertor strategy is improved.In the strategy, master thyristor is used to absorb residual power on resonant capacitor toprevent injection of residual power on resonant bypass into load, and feedback can beimplemented without serial connection to feedback diode, which reduces systemic loss. Apower resistor with proper resistance is added between inductor and capacitor on thyristorbypass to impede over-speed rise of resonant current. Besides, an improved charging circuitis put forward. With the circuit, capacitor can be charged locally with line voltage withoutneed of adding voltage source. The software-hardware combined capacitor chargingtechnology makes charging time and charging quantity controllable.Based on introduction to conditions for triggering thyristor and analysis on a fewthyristor analog trigger technologies, a new-type digital trigger circuit is put forward basedon DSP control system. The circuit features low power consumption, high accuracy, goodpulse symmetry, stability and easy debugging, setting, modification.This paper introduces the principle of dq0detection algorithm for three-phase voltage.Apower signal hardware detection module is designed, and a complete set ofsoftware-hardware detection system for three-phase voltage is developed in conjunctionwith actual application system of STS.Software-hardware design solution of complete set of STS system is introduced.Thesystem can quickly process a series of complicated signals e.g. digital signal, low-voltagesignal, low-current signal, and largely improve artificial intelligence of STS monitoringsystem with optimal algorithm and information fusion. Both software and hardware of the system have expandability, changeability and compatibility. Based on power supply ofdigital frequency converter, a new-type intelligent STS system with UPS is put forward.Abundant experiments show that the system can finish switching within8ms and it canbe up to requirement of sensitive load for UPS.It is expected to be used in ship powersystem.