New Analysis Framework of Lyapunov-Based Stability for Hybrid Wind Farm Equipped with FRT: A Case Study of Egyptian Grid Code

Abstract

Due to the continuous increase of fuel prices and pollutions, the use of renewable energy especially wind has increased. In developing countries including Egypt, squirrel cage induction generator wind turbine (SCIG- WT) represents a considerable proportion of the total capacity of installed wind farm due to its qualities such as low cost and easy availability. However, its operation has a substantial effect on system stability. In contrast, doubly fed induction generator wind turbine (DFIG-WT) is broadly penetrated the electrical grid as it keeps the system stable. In this work, the ability of WT generators to continue operating rather than tripping at the time of faults is analyzed for proper stability investigation. The detailed control and stability of a grid-connected large scale SCIG and DFIG of Zafarana, Suez Gulf area, Egypt are discussed whereas the parameters of fault ride through (FRT) curve of Egypt grid code is utilized. Moreover, a precise analytical stability argument using a proposed integrated nonlinear dynamical model is presented. Conditions for global asymptotic stability of the SCIG in the sense of Lyapunov function (LF) are given and tested by time domain simulation. The eigenvalues of the matrices of LF and its derivative are determined by which the stability boundaries are determined depending on the positivity of these matrices. The dynamic behavior of the whole system is simulated in MATLAB/Simulink interface programming while the practical data are collected from an experimental model consisting of DFIG-WT to demonstrate the efficacy of the FRT control system.