Control of wide-speed-range operation for a permanent magnet synchronous generator-based wind turbine generator at high wind speeds

Abstract

Wind turbine generators (WTGs) contain plenty of inertia in their rotating masses, which has great potential for exploitation. Traditionally, WTGs are operated with the rated rotational speed at high wind speeds, which cannot accelerate further to absorb kinetic energy (KE). In this paper, a control method achieving a wide-speed-range operation for a permanent magnet synchronous generator (PMSG)-based WTG at high wind speeds is proposed. The proposed method can permit the WTG to operate steadily at any desired speed over an allowable range, rather than fixed to the rated speed. Thus, the rotating masses can not only decelerate to release substantial KE as previous works, but also accelerate to absorb considerable KE, which acts as a flexible virtual flywheel energy storage system (VFESS). The equivalent capacity of the VFESS is analyzed in theory, based on the analysis for feasible operation range of rotational speed at high wind speeds. The performance of the proposed control method is verified considering normal operation, extra active power demand and low voltage ride through scenarios, based on EMTP-RV generated data. The results demonstrate that the proposed method can make a WTG operate steadily at any preset speed over a wide range and generate the rated power at high wind speeds. The VFESS can either absorb or release considerable energy without additional cost. In addition, the discussions on the potential prospect of KE in WTGs and the transition ways of rotational speed at high wind speeds are also investigated.