Modelling and analysis of distributed power generation schemes supplying unbalanced and non-linear load

Abstract

This study presents a combined control strategy for stand-alone distributed power generation scheme, utilizing the squirrel cage induction generator (SCIG), and the permanent magnet synchronous generator (PMSG) in its structure. The combined control consists of both the machine side and load side converter control. The proposed load voltage controller, cascaded with the inner filter current controller, is designed for a load-side converter (LSC) to remove the harmonic component during non-linear loading and negative sequence component in case of unbalanced loading respectively. The control algorithm ensures to produce constant load voltage amplitude and frequency, with the change in both input power and non-linear and unbalanced loading scenarios. It also guarantees the sinusoidal load voltage under the mentioned loading conditions. Simultaneously, the dc-link voltage controller cascaded with the inner q-axis stator current controller is used for machine side converter (MSC) to keep the dc-link voltage at the prescribed level for both SCIG and PMSG during all the operating conditions. In this paper, an analysis of both the distributed generators based wind energy conversion systems under vector control for MSC provides the enhanced machine variable performance. The proposed control scheme is successfully implemented in MATLAB/Simulink environment. One scaled experimental prototype is developed, and real-time results are shown in the paper to validate the theoretical claims of the controllers.