Improvement Of Fault Ride Throuhg Capability Of DFIG Based Wind Turbines

With increased penetration of wind energy as a renewable energy source, there is a need to keep wind turbines connected to the grid during di erent disturbances such as grid faults.Grid connected wind turbine doubly fed induction generators (DFIGs) are sensitive to dips in supply voltage,so-called "grid faults".Fault ride through systems must be designed to manage large and potentially dangerous fault currents in both stator and rotor circuits.This enables wind farms(WFs) to endure grid voltage dips avoiding WF-grid disconnection.A novel adaptive strategy can be used to obtain technically justi ed fault ride through requirements for wind turbines(WTs).The main objective of this strategy is to promote an e ective integration of WTs into power systems with still low penetration levels of wind power based on technical and economic considerations.The level of requirement imposed by the strategy is increased stepwise over time, depending on system characteristics and on wind power penetration level.The idea behind this strategy is to introduce stringent requirements only when they are technically needed for a reliable and secure power system operation.The use of superconducting fault current limiter(SFCL) improves the FRT capability of the system.Inferences ensure that SFCL is ef ective in decreasing the fault current.Moreover, both the voltage dip at the generator terminals and the reactive power consumption from the grid are decreased during fault.The voltage dip characteristics are discussed in accordance with the international grid codes for wind turbines.

• Wind Generator Topologies

>Fixed Speed Induction Generator (FSIG)

>Doubly Fed Induction Generator (DFIG)

• FAULT RIDE THROUGH CAPABILITY

>Introduction

>Adaptive Strategy

>Requirement Levels

>Methodology

>WT-Technologies

• IMPROVEMENT OF FRT USING SFCL 

>SFCL Model

>Simulation Results 

>Stator Current Behavior

>Rotor Current Behavior

>Basic con guration of an FSIG wind turbine

>Basic con guration of a DFIG wind turbine

>FRT requirement for WTs according to the AS-FRT

>General diagram to obtain the AS-FRT

>Schematic diagram of DFIG-based wind turbine with SFCL

>Superconductor E - J characteristic, showing three states

>Stator current behavior with and without SFCL

>Change of rotor current under fault with and without SFCL

>Voltage-dip characteristics at the generator terminals

>Active and reactive power responses

>Reactive power response

>E ect of SFCL resistance on stator currents

>E ect of SFCL resistance on voltage dip at the generator terminal 

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Key:Wind turbine improvement system,wind turbine control systems,power system seminar reports,Doubly fed induction generator(DFIG),Fault ride-through(FRT) capability, grid code, transient stability, voltage stability support, wind power, wind turbine,superconducting fault current limiter(SFCL)