Improve the Power Quality of Wind Power Plant by Modifying the Theory of Instantaneous Active and Reactive Power

Abstract

One of the most important issues in the clean energy topics is related to the clean electricity generation with desired quality. Low quality electricity causes increasing the losses, mis-operation of the protection relays, saturation of iron core transformer and etc. Hence, it seems necessary to supply electricity with acceptable quality satisfying related standards such as IEEE-519. Quality of the power generated by wind turbines should be investigated and in order to improve its performance, some strategies should be taken if needed. A wind turbine is connected to the grid through a converter. Traditional converters are fixed-speed and the advanced systems are variable-speed. The most important advantage of the advanced systems is related to the mitigated mechanical stress and increasing of the energy capacity. Rectifier and inverter are involved in the topology of variable-speed machines. In this paper, a mathematical model of this system i.e. variable speed machine which is defined in the rotating reference frame of rotor is presented. Rectifiers and inverters contains some power electronic elements which are the major causes of harmonic generation because of their nonlinear characteristics. Harmonics are the one of the most important phenomena decreasing the power quality. Therefore, it seems that mitigation of the harmonic will be necessary. Shunt active filter is used to reduce the current harmonics. This filter has three components namely identification, modulation and inverter. Some of the identification methods are sensitive with respect to the input voltage harmonics. So, an algorithm which shows the better performances, has been used in the identification part. Finally, performance of the mentioned filter has been proved through the simulation