Speed control method of double salient electro-magnetic wind power generator in full range of wind speed

Abstract

For a variable-speed wind power generation system equipped with the fixed-pitch wind turbine and doubly salient electro-magnetic generator (DSEG), the rotational speed can't be changed by pitch control. In this paper, a novel speed control method based on excitation current control of DSEG wind power generator (DEWG) in full range of wind speed is studied, based on their characteristics. It is composed of three-stage methods, which are maximum power point track (MPPT), constant speed control and constant power limit. So the safety, efficiency and stability of the whole system can be ensured. Effectiveness of the proposed methods is verified by Hardware-in-the-Loop (HIL) simulations, which adopt the real controller and real time simulation platform.Keywords -DSEG; wind power generation system; full range of wind-speed; speed control; three-stage method I. INTRODUCTION DSEG is a novel type of brushless DC machines, with the advantages of simple structure, flexibility control, and high efficiency, etc. Its application in wind power system will cut down the cost of generating and improve the reliability of system.The speed control method in full range of wind speed is needed to ensure the safety, efficiency and stability of the whole system. At present, a number of existing methods have been used in speed control of wind power system already. The method of pitch control changes the attack angle by adjusting the pitch angle of the blade. Further, the power and torque captured by wind turbine are controlled. This method can maintain constant output power in high wind speed range. However, the control system is complex and a variable distance mechanism is needed. Using the stall performance of the blade profile, the stall control method can limit the output power without a variable distance mechanism. But the stall degree deepens with increasing wind speed, so it hardly keeps constant output power in high wind speed range.Compared to the conventional permanent-magnet machine and doubly-fed induction generator wind turbine, the torque of DSEG can be controlled by adjusting the excitation current so a quicker response