Some investigations on primary frequency response analysis of grid connected variable speed wind energy conversion systems

Abstract

Growing concern about global warming due to environmental pollution generated by fossil fuel resources has become the main motivation to increase the penetration of Renewable Energy Sources (RES) into the grid. Power generation from wind has been considered as more economical and environment-friendly. With the projected growth of wind power generation, the impact of renewable power on power system dynamics is a concern for Transmission System Operator (TSO). The major issue of integrating the large scale Wind Turbine Generators (WTG) in to the grid is the impact on frequency stability. Grid frequency deviation can be mitigated by inertial response, primary frequency control and secondary frequency control of conventional synchronous generators. Hence, it is important to consider generation -load balance to prevent system being disconnected by under frequency relays. Doubly Fed Induction Generator (DFIG) (Type 3), Permanent Magnet Synchronous Generator (PMSG) and Induction Generator (Type 4) based Variable Speed Wind Energy Conversion Systems (VSWECS) are considered for the analysis due to their optimal power extraction and efficient operation than fixed speed counterparts. In order to overcome the frequency stability issues, the frequency control technique must enable the VSWTG s to contribute to regulating the grid frequency. With supplementary control, the rotational speed of VSWTs is varied over a wider range to provide active power support during grid frequency excursions. newline