Feed-Forward Characteristic

This chapter describes the use of predictive feed-forward control as a means of improving the performance of a hydroelectric plant in achieving its target for delivered power, while operating in grid (power system) frequency control mode. Due to the gravitational limit on the acceleration of water in the supply tunnel, a hydraulic turbine is always subject to some delay between opening or closing its guide vane and the consequent change in power. The effect of this delay on a unit working in frequency-control mode can be alleviated by predicting 2–3 s ahead what power will be required and using this information as a feed-forward signal to supplement a PI feedback controller. This chapter outlines the theory for frequency prediction and disturbance feed-forward control and shows how they can be applied to the problem of tracking a power target.