Fuzzy Logic Based MPPT for a Wind Energy Conversion System Using Sliding Mode Control

Wind energy is one of the most promising and developed renewable energy resources. A power electronic interface is needed in order to connect a Wind Energy Conversion System (WECS) to the load or the utility grid. Control of this interface, which consists of generator- and grid side converters, is a very important and demanding task. The main purpose of controlling the generator-side converter is implementing Maximum Power Point Tracking (MPPT). In this paper, the conventional Hill Climbing Search (HCS) MPPT algorithm is modified using fuzzy logic theory in a way that its performance has been enhanced in terms of accuracy and speed. This modified algorithm enables the system to continuously extract the maximum energy from the wind by generating an appropriate rotor speed reference. Vienna rectifier is used as the generator-side converter due to its noticeable advantages in WECSs. A non-linear control scheme based on Sliding Mode Control (SMC) is utilized in this work for efficient speed control, which has notable advantages over linear controllers. Simulation results verify the satisfactory performance of the control scheme and the modified MPPT algorithm. A comparison is also made between SMC and PI controllers regarding their speed control performance.