Impact of nonsinusoidalness on Efficiency of alternative electricity generation systems

Abstract

The task of reducing the energy loss is especially important for alternative electricity generation systems from renewable sources. In electromechanical systems with variable angular speed of permanent-magnet synchronous generator (PMSG), the harmonic components of generator voltages and currents in transient and steady state have impact on energy efficiency. This paper compares the energy performance of basic schemes of taking of power from PMSG in a wind generation system. It investigates the nature of harmonic distortions of voltages and currents at the generator load on the diode bridge and assesses their impact on energy efficiency in steady-state under different wind speeds and, consequently, power. The PMSG load on active rectifier is characterized by minimal losses, but harmonic distortions appear there in transient conditions, which dominate in the alternative power plants. The paper suggests compensating of loss from transitional harmonics by the way of regulation of the generator's excitation. Simulations results are presented to illustrate the performance of the proposed method.