A Novel Method of Equivalencing DFIG based Wind Farm for Stability Studies

Objectives: Analyzing the stability of large scale wind power plant (WPP) is very cumbersome and simulation time required performing the analysis is long-drawn-out. Thus a single equivalent model of WPP is developed. Methods/Statistical analysis: Kron’s based network reduction is proposed for the WPP. Two network reduction methodologies are adopted and wind turbine mechanical and electrical parameters are rescaled which is discussed in detail in the paper. Transient stability analysis is performed to validate the equivalence method. Study system consists of 23 buses with 20 DFIG wind turbine generating units connected to the main grid of utility system. Findings: Transient stability analysis is conducted for the study system. Dynamic response of detailed WPP and proposed equivalent system matches accurately for the three phases to ground fault disturbance at point of common coupling (PCC). At PCC the Voltage, Real power and Reactive power values are very close to proposed equivalent system when compared to detailed WPP. In addition, the percentage error computed is least for the proposed system. Time taken to simulate the equivalent system is very less compared to the detailed WPP and existing literature work. All the simulations are carried out in DIgSILENT Power Factory^TM software. Application/Improvements: Remarkable simulation time reduction and accuracy is achieved for the proposed method. Thus, the equivalent method is applied for quick assessment of transient stability of large scale WPP.