Control of energy storage systems for three-phase applications

This paper deals with control of a kVA-rated power conversion system containing energy storage devices used for three-phase applications. Two main operating modes are possible: grid-feeding, when system operates as a power source connected to the grid, and grid-forming (standalone), when system operates as a voltage source supplying an islanded load. A two-level global control architecture is employed for both cases, which relies on three-phase current control in the αβ frame as inner loops. Proportional-resonant (PR) controllers are used to this end. This paper discusses PR controllers design and numerical implementation and proposes a solution to deal with the parameter-varying nature of plant, exhibited especially in the off-grid case. Opportunity of using Smith predictor schemes for compensate pure delay due to digital pulse-width modulation (PWM) is also analyzed. MATLAB^®/Simulink^® simulation results illustrate the proposed control approach effectiveness.