Operation control of paralleled three-phase battery energy storage system

Parallel operation for capacity enlargement of three-phase battery energy storage system (343 BESS) is presented. The proposed paralleled system consists of some inner-loop parallel-connected current-regulated pulse width modulated (CRPWM) converters, a current command distributor and an outer-loop common contro1:ler. Every single-module CRPWM 343 converter possesses good current tracking control characteristics, so is easy to parallel connect. The proposed current command distributor receives current commands from the common controller and generates suitable current commands for each paralleled converter module according to the proposed current sharing control strategy. The sophisticated system arrangement of the common controller gives the BESS many power processing functioins. When it is connected to the utility grid, it can be arranged to give peak load shaving, active power filtering, power factor correction and battery charging. In the event of utility failure the BESS can supply uninterrupted power with low distortion sinusoidal voltage waveform to critical loads. Performance of the proposed paralleled BESS at various operating conditions is demonstrated experimentally.