Real-time replication of a stand-alone wind energy conversion system: Error analysis

This paper provides adequate information about the problem of real-time replicating in laboratory conditions. The dynamic behavior of stand-alone low-power wind energy conversion systems (WECS) in response to the wind speed variations and also to the electrical load variations is replicated. The investigated system consists of a variable-speed wind turbine based on a permanent-magnet synchronous generator (PMSG), a diode bridge rectifier, a DC-DC step-down converter and a wide range DC load. Because of reduced noise level and better steady-state accuracy, a speed-driven hardware-in-the-loop physical WECS simulator has been used to accomplish this task. Its significant drawback - that is, a reduced bandwidth - has been significantly alleviated by using an enhanced software simulator structure which uses a feed-forward compensation of the inherent physical disturbance produced by the generator torque variations. Both time-domain experimental results and a thorough frequency-domain error analysis show good replication performance in the frequency range of variation of both wind speed and electrical load.