Design of Electro Hydraulic Actuator

Abstract

In this research, a non-linear model for the guide vane electro hydraulic actuator of turbine no.4 at Rosaries Hydro Power Station has been developed using MATLAB/SIMULINK integrated environment, and the performance of the model is compared with the real plant using a state feedback controller and a PID controller with the same (PID) gains as built in the real plant. The performance of the two controllers is investigated. To understand the dynamic behaviors of the system, it has been represented by 3ed order differential equations defining the dynamics of plant, and using a fact that the dynamic pressure changes in the hydraulic cylinder chambers becomes linearly dependent on cylinder chambers volumes above and below some prescribed cut off frequencies, the order of system equations reduced to 2ed order. Then these equations were used to design the state feedback controller, so as to control the non-linear model. For the position control of the single rod hydraulic actuator, state feedback gains are determined by using the linear reduced order system equations. The dynamic performance of the system is investigated by running open loop and closed loop frequency response and step response tests.