T. Geetha

Bio: T. Geetha is an academic researcher from Indian Institutes of Technology. The author has contributed to research in topics: Electric power system & AC power. The author has an hindex of 1, co-authored 2 publications receiving 4 citations.

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

Stability Assessment of Power System Models For Higher Wind Penetration

Abstract: For grids of low X/R ratios voltage control through active power is effective in reducing the voltage at the point of interconnection of wind farms to grid Active power voltage control can be achieved using energy storage schemes or inter connectors In this paper we propose variable frequency transformers (VFT) as an effective means of interconnecting synchronous or asynchronous regions to enhance wind penetration It is shown that the steady state stability limits of the system are improved with VFT as inter connectors Also the performance of the VFT under open circuit and short circuit conditions are evaluated

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

Abstract: Conventional grid connected synchronous generator (SG) based wind energy generation system (WEGS) incorporates sophisticated power electronic control system in it which produces harmonics and this deteriorates the quality of output power. Hence, this paper presents a new method for grid integration of SG based WEGS using variable frequency transformer (VFT). The proposed method does not employ any power electronic based interface for grid integration of SG based WEGS and hence does not produce harmonics. Moreover, control of the proposed method is simple. In order to realize the proposed scheme, a digital simulation model of the proposed method has been developed under MATLAB/ Simulink environment. The power flow from the SG to the grid using the model has been studied and its results have been discussed.

Variable Frequency Transformer - State of the art review

Abstract: The Variable Frequency Transformer (VFT) is basically a controllable, bidirectional transmission device that can transfer power in-between asynchronous power system networks. The construction of VFT is similar to conventional asynchronous machines, where the two separate electrical networks are connected to the stator winding and the rotor winding, respectively. One power system is connected with the rotor side of the VFT and another power system is connected with the stator side of the VFT. The electrical power is exchanged between the two networks by magnetic coupling through the air gap of the VFT and both are electrically isolated. This paper gives an overview about core components, commissioning, mechanical design, model, operation, analysis and applications of VFT.