Pitch Control of a Digital Hydraulics Pitch System for Wind Turbine Based on Neuro-Fuzzy Digital Pitch Controller

Abstract

Digital Hydraulics has been implemented in the hydraulic pitch system of Wind Turbine (WT) which aids in uniform power generation at above-rated wind speeds. A novel Digital Hydraulic Pitch System (DHPS) model which uses a hydraulic motor as the end actuator was established and a wind generator system model was developed. Further, a Neuro-Fuzzy Digital Pitch Controller (NFDPC) with two distinct neuro-fuzzy controllers was employed in the developed models. Two comparative studies are conducted and in these studies, the proposed NFDPC was compared with Proportional Integral Derivative Cascade Controller (PIDCC) where PID is implemented in inner and outer loop. In the first comparative study (considering custom wind speed), results revealed that the proposed controller maintains rated generator speed than PIDCC. The Root Mean Square Error (RMSE) (between rated speed and generated speed) of the generator was 1.23 and 3.73 for the proposed and PIDCC, respectively. Thus, uniform power was generated. Consequently, in the second case study (real-time effective wind speed), the proposed controller maintains optimal generator speed with a minimal RMSE of 0.66 when compared to PIDCC with an RMSE of 3.55. Thus, uniform power was developed by the proposed controller. Therefore from these results, the proposed controller generates uniform power at above-rated wind speed with large wind fluctuations.