Research On Cascaded STATCOM And Its Realization Based On DSP

With the development of power industry，the requirement for electric power qualityand reliability is much higher now, Flexible AC Transmission System (FACTS) has beenrapidly developed as an efficient technology to improve electric power quality. As a novelreactive power compensation device, Static Synchronous Compensator (STATCOM) isone of the key technologies of FACTS, and also the development direction of modernreactive power compensation device. It is applied more and more extensively in powersystem for its superior compensation performance.The voltage class in modern power system is increasing, which requires theSTATCOM be corresponding to higher voltage and larger capacity. Two methods arecommonly used to improve the voltage level and capacity, transformer multiplextechnology and multi-level technology, in this paper the multi-level technique is chosen,and chain STATCOM which based on H bridges cascaded multilevel inverter is selectedas the main circuit. This paper analyzes the mathematical model of the chain STATCOM,and gives a reasonable control strategy according to the model, of which the current closedloop is controlled with nonlinear decoupling method, unipolar dual-frequency carrierphase-shifted sinusoidal pulse width modulation (CPS-SPWM) control method is appliedto H bridge cascaded multilevel inverter. In order to verify the feasibility of the controlmethod and the compensation performance of the STATCOM device, the model of thewhole system is built on the PSIM platform and the static and dynamic performance havebeen simulated. Moreover, the hardware and software of the system are designed based onDSP2812controller, wherein two H bridges cascaded five level inverter in single-phase isadopted as the main circuit topology. Finally, experiments are conducted.The simulation and experimental results show that the modulation performance ofunipolar dual-frequency CPS-SPWM is excellent, and the compensation effect ofSTATCOM based on the H bridge cascaded multilevel inverter can been achieved well.