A novel control algorithm for inverter-based distributed generation in unbalanced three-phase power systems

In distribution power system, the unbalanced operating state, harmonics, negative sequence components, which are caused by the nonlinear or unbalanced loads, not only increase the power transmission losses, but also are harmful to the electric devices. In this situation, the Active Power Filter (APF) and the Static Var Generator (SVG) would be required. However as proved in this paper, the existing compensation methods are usually affected by the unbalanced and harmonic voltages. So a compensation algorithm based on the amended Park Transformation which is suitable for the unbalanced power systems is proposed. In addition, referring to the inverter-based distributed generation (IBDG) developed rapidly in recent years, the presented compensation algorithm is integrated with the active power control scheme to build a hybrid control algorithm used in IBDG existing distribution system. Based on the stated control algorithm, IBDG not only can supply the electric power, but also compensate for the reactive power, harmonics and negative sequence currents of the distribution power system. The feasibility and accuracy of the algorithm are verified by the DIgSILENT Powerfactory simulation.