Variable Frequency Transformers for Increased Wind Penetration

Abstract

The voltage impact of wind farms on weak grids is studied using a generic test system. The size of the wind farm is taken as 20% of the grid short circuit MVA to characterize weak grids. The voltage at the point of interconnection (POI) of the wind farm to the grid is analyzed for different values of grid X/R ratios. It is shown that reduction of real power injection at POI brings the voltage at POI within permissible values for the entire range of X/R ratios. A pumped storage unit or a variable frequency transformer as an asynchronous inter connector is suggested to realize this. Complete modeling and simulation of the proposed network topologies are given. The results are discussed with reference to the Indian power system. IndexTerms-pump storage, variable frequency transformers, wind energy.

A novel method for grid integration of synchronous generator based wind energy generation system

“…VFT has emerged as a flexible ac link which can be used as a tie within synchronous, in-between synchronous and in-between asynchronous power system networks. Recent studies have indicated that the application of VFT in wind power generation could provide effective wind power utilization at small as well as large scale [10] - [12]. In the paper VFT is used for grid integration of synchronous generator (SG) based wind energy generation system.…”