Enhancing low voltage ride through and transient stability of wind driven dfig with adaptive controllers

Abstract

newlineEnvironmental concern and the perpetual increase in demand for electricity have necessitated finding alternative energy sources and devising methods to utilize existing renewable sources more efficiently. In recent decades, concerns regarding carbon emissions, climate change and limitation of fossil fuels have lead to a large increase in generation of electricity via renewable resources. Wind energy has been one of the most successful of these new additions to the generation pool. The rapid growth of electric power generation from wind is largely credited to the Doubly Fed Induction Generator (DFIG) technology. As penetration of wind energy has reached a substantial level, new power system operation issues have raised. One of the imperative concerns related to working of wind farms is the low voltage event during the presence of fault. The voltage drop produces adverse effects on wind turbines. Generally wind turbines are vulnerable to higher wind penetration and grid faults. In those conditions the protection of DFIG must be guaranteed to ensure the safe operation against over current and undesirable dc link voltage. The common solution, referred to as a crowbar , essentially short circuits the rotor windings to prevent excessive currents. However, this also effectively disables the machines and disconnects it from the grid, so the crowbar itself is not an effective aid. According to the new operational strategies, wind farms must be continuously connected to the grid without any interruption and provide reactive power for supporting the grid voltage during the grid faults. This capacity of wind farms is known as the Fault Ride Through (FRT) capability and also as the Low Voltage Ride Through (LVRT) capability.