Medium Voltage Chain STATCOM Control Strategy And Device Research

Along with the development of electrified railway in our country and the improving of the electrified railway transport capacity, the problem of reactive power and harmonic power quality caused by the traction power supply load is becoming serious. Become an important factor affect the safe and stable operation of power quality and the system of electric railway load, This paper based on the governance electrified railway power quality problems as the background, Additional research the chain STATCOM control strategy, the chain STATCOM compensate the reactive current in traction load, at the same time, suppress harmonic current, achieve the multi-objective control chain STATCOM. This paper mainly focuses on the above research.The mathematical model is the foundation of control strategy. This paper starts with the basic working principle of chain STATCOM, based on the switching function, deduced the chain switch cycle average model of STATCOM, near the dc working point is used to analyse the system small signal disturbance linearization method, the ac small signal model of the system, which laid a foundation for design of the chain STATCOM control strategy.Reactive power and harmonic current detection accuracy is the premise of the chain STATCOM control objectives. This paper simply introduced the system of three-phase reactive power and harmonic current detection method for the traditional single-phase system, for the delay of the traditional single-phase system reactive power and harmonic current detection, presents a single-phase system reactive power and harmonic current detection method without delay.Suspension capacitor voltage balance control is the premise of STATCOM can be stable and safe operation. This article through the analysis of the variation law of cell suspension capacitor voltage, puts forward a kind of capacitor voltage balance control based on instantaneous active power control strategy, and considering the traditional PI regulator in the single-phase system cannot afford to astatic track the given signal communication, presents a astatic tracking ac signal more PR parallel regulator, after analyzing the dead zone effect of chain STATCOM, raises a dead zone compensation method based on invalid device.Reactive power and harmonic current compensation method is the key technology of chain STATCOM. This article expounds the multiple objective overall chain STATCOM control strategy and control block diagram, finally the control strategy’s feasibility is certificated by Matlab/Simulink.After defining the control strategy of the system, this paper introduces the design of the chain STATCOM control system platform, including the hardware design of control panel and the DSP, FPGA software design of the program.Finally, the chain STATCOM do the experiment based on semi-physical simulation platform and industrial prototype for5chains STATCOM, and the experimental results were briefly analyzed.