A new simplified model for assessment of power variation of DFIG-based wind farm participating in frequency control system

Abstract

Due to the ever-increasing use of wind farms (WFs), an investigation of their impact on the power system stability and control is essential. Especially, assessing the active power variation of WF is one of the important issues, since it can affect the power system frequency. Unlike traditional power plants, a WF consists of many units (wind turbines) with different operating conditions; therefore, studying the behavior of each unit is necessary and this kind of study undoubtedly involves a myriad of calculations. This paper aims to propose a simple and effective equivalent model for a DFIG-based WF participating in the frequency control system. The model is intended to accurately show the behavior of WF as well as individual wind turbines. It is analytically shown that under nominal frequency conditions, a first-order system can accurately evaluate the WF output power. Also, the paper deals with further considerations that should be taken during frequency disturbances to preserve the accuracy. In order to verify the accuracy and effectiveness of the proposed model, the performance of the proposed model is compared to the detailed and the conventional models.