717 publications from this institution
This paper presents a battery energy storage system with a modular push-pull PWM converter (MPC), which is intended for grid connection to medium-voltage or high-voltage power systems. The converter is equipped with a center-tapped transformer and two arms consisting of a cascade connection of multiple bidirectional PWM chopper-cells with floating dc capacitors. This paper discusses the operating performance and control method of the MPC, to achieve voltage balancing of all the floating capacitors. Moreover, a comparison is made between the MPC and a modular multilevel converter (MMC) as the battery energy storage system. The validity of the concept and control method developed in this paper is confirmed by computer simulations using the “PSCAD/EMTDC” software package.
This paper deals with a self-commutated back-to-back (BTB) high-voltage direct-current (HVDC) link system for the purpose of power flow control and/or frequency change in transmission systems. Each BTB unit consists of two sets of 16 three-phase voltage-source converters, and their AC terminals are connected in series each other via 16 three-phase transformers. Hence, the BTB unit uses totally 192 switching devices capable of achieving gate commutation. This results in a great reduction of voltage and current harmonics without performing PWM control. Simulation results verify the validity of the proposed system configuration and control scheme not only under a normal operating condition but also under a single-line-to-ground fault condition.
