Power flow analysis and control of delta compensated UPS with grid voltage fluctuation

Delta compensated UPS can compensate ± 15% fluctuation of the grid voltage. In this condition, UPS supplies a stable sinusoidal voltage and maintains the input and out power balance by regulating the input current. The power balance is completed by cooperative work of the two converters, one converter operates in the rectifier state, and the other one operates in the inverter state, so that ensure the load is normal. This paper presents a detailed analysis of the power flow of Delta compensated UPS with the grid voltage fluctuation. Based on the control strategy given in this paper, Matlab simulation results verify the validity of the theoretical analysis and control strategy.