Wind Turbine Simulators

Abstract

Electricity generation using wind energy has been well recognized as environmentally friendly, socially beneficial, and economically competitive for many applications. Wind turbine simulators (WTS) are important equipments for developing wind energy conversion systems and are used to simulate wind turbine behavior in a controlled environment without reliance on natural wind resources, for the purpose of research and design into wind turbine drive trains, especially energy conversion systems. Wind turbine simulators can significantly improve the effectiveness and efficiency of research and design in wind energy conversion systems. The simulator can be used for research applications to drive an electrical generator in a similar way as a wind turbine, by reproducing the torque developed by a wind turbine for a given wind velocity. Also, it can be used as an educational tool to teach the behavior, operation and control of a wind turbine. Usually induction motor, separately excited DC motor and permanent magnet synchronous motor can be used to reproduce the static and dynamic characteristics of real wind turbines. In the past few years, there have been many studies on wind turbine simulators. Authors of (Nunes et al., 1993), (Battaiotto et al., 1996), (Rodriguez et al., 1998) and (Monfared et al., 2009) utilized separately excited dc motors with controlled armature current. (Nunes et al., 1993) presented a wind turbine simulator using the electromagnetic (EM) torque equation of a dc machine. The armature and the field circuits were controlled so that the dc machine generated the static characteristics of a constant pitch wind turbine. (Monfared et al., 2009) , (Rabelo, et al., 2005) and (Guangchen, et al., 2010) utilized separately excited dc motor to reproduce the static and dynamic characteristics of real wind turbines. The wind turbine simulator described in (Monfared et al., 2009) aims to reproduce the mechanical behavior of wind turbine rotor, drive train and a gear box under dynamic and static conditions. The reference for the torque developed by the wind turbine includes the gradient and tower shadow effects that result in pulsating torques. The larger inertia effect and the steady-state behavior of real wind turbine are also included in the paper. In (Nichita et al., 1998) a more general approach of WTS was presented by the application of a dc motor. In (Jian & xu, 1987) a microcomputer-controlled SCR-DC motor was used to supply the shaft torque. A dc machine, although is ideal from the standpoint of control, is, in general, bulky and expensive compare with an AC machine and it needs frequent maintenance due to its commutators and brushes. Inverter driven PMSM can also work like a real wind turbine (Weihao Hu, et al., 2009), (Xu, Ke, et al., 2007). The wind turbine simulator consists of a