A new control method of permanent magnet generator for maximum power tracking in wind turbine application

This paper discusses a new and simple control method for maximum power tracking in a variable speed wind turbine by using a step-up dc-dc converter. The output voltage of permanent magnet generator is connected to a fixed dc-link through a three-phase rectifier and the dc-dc converter. A maximum power-tracking algorithm calculates the speed command that corresponds to maximum power output of the turbine. The dc-dc converter uses this speed command to control the output power of the permanent magnet generator, such that the speed of generator tracks the command speed. A current regulated PWM voltage source inverter maintains the output voltage of dc-dc converter at a fixed value by balancing the input and output power to the dc-link. In addition, the inverter can improve power factor and inject a current with very low harmonic distortion into the utility grid. The generating system has potentials of high efficiency, good flexibility, and low cost.

I. Introduction

Maximized electricity generation by wind turbines is an interesting topic in electrical engineering and many types of variable speed generating systems have been researched to achieve this goal. Use of a variable speed generating system in wind power application can increase the captured power from wind. In fact, the system based on permanent magnet generator (PMG) is one of the most favorable and reliable methods of power generation. However, electricity generated directly by PMG has variable amplitude and frequency, requiring additional conditioning to meet the amplitude and frequency requirements of the utility grid and/or conventional loads. Many types of power electronic converters were introduced to find an appropriate and inexpensive solutions to the problems of electricity conditioning and the results are promising [1][2][5].