Fuzzy Logic based Digital Hydraulics Control of Blade Pitch Angle in Wind Turbines

Abstract

Pitch control system is generally employed in wind turbine to mitigate load and maintain uniform power generation at above-rated wind speed regions. Hydraulic system has more power to weight ratio and so it is incorporated in the pitch system of large scale wind turbines. Some of the issues related to the usage of conventional valves in Hydraulic Pitch System (HPS) are: internal leakage, throttling losses, high power loss, less fault-tolerant, requires high manufacturing tolerance and more sensitive to contamination. In order to overcome these issues, digital hydraulics technology should be introduced as Digital Hydraulics Pitch System (DHPS). Commercially, Proportional Integral Derivative (PID) controller is used as pitch controller but these controller performance doesn’t hold good when excessive disturbance or change in operating point occurs in the system. So, heuristic-based Fuzzy Logic Controller (FLC) is preferred which has the ability to surpass the PID problems. In this paper, heuristic FLC based control strategy is proposed for a novel DHPS configuration to control the pitching action. Simulation model of DHPS is developed and system simulations are conducted. The comparative study on the effectiveness of FLC for DHPS and conventional valve controlled HPS is conducted.