Impacts of distributed generation on stability of electrical power systems

Abstract

Environmental concerns, market forces, and emergence of new technologies have recently resulted in restructuring electric utility from vertically integrated networks to competitive deregulated entities. Distributed generation (DG) is playing a major role in such deregulated markets. When they are installed in small amounts, their impacts on the system may be negligible. When their penetration levels increase, however, they may start affecting system performance from more than one aspect. System transient stability needs to be re-assessed after the emergence of DG. This thesis attempts to address the impact of DG on system stability under different operation conditions. Wind Energy Conversion Systems (WECS) are involved as a DG technology. Dynamic models for different system components such as synchronous and induction generators, and Wind Turbines are presented first. Then, the impacts of WECS on the stability of an electrical power system are addressed taking into account different ratings and installation locations. After that, an attempt to enhance system stability is performed using optimized STATCOM control schemes and Power System Stabilizers (PSS) whose parameters are tuned up using Genetic Algorithm (GA) for optimum control. Time-domain simulations are carried out under different WECS penetration levels and installation location within the grid. Simulation results show that STATCOM has contributed to an enhancement in the transient stability of induction generators. Moreover, they show the effectiveness of the optimized PSS in damping out synchronous generators’ rotor angle oscillations.