The frequency-independent control method for distributed generation systems

In this paper a novel frequency-independent control method suitable for distributed generation (DG) is presented. This strategy is derived based on the abc/αβ transformation and abc/dq transformation of the ac system variables. The active and reactive currents injected by the DG are controlled in the synchronously rotating orthogonal dq reference frame. The transformed variables are used in control of the voltage source inverter that connects DG to distribution network. Due to importance of distributed resources in modern power systems, development of new, practical, cost-effective and simple control strategies is obligatory. The new control method of this paper does not need a Phase Locked Loop (PLL) in control circuit and has fast dynamic response in providing active and reactive power to nonlinear load. From extensive simulation results, high performance of this control strategy in DG application is demonstrated with improved voltage profile, increased power factor and reduced total harmonic distortion.