Predictive control method for wind power regulation via a double‐screw expander‐generator and supercapacitor

A modified hybrid energy storage system (HESS) consisting of a double‐screw expander‐generator (DSEG) and a supercapacitor is proposed here to accommodate wind power fluctuations. The dynamic matrix control (DMC) algorithm is applied to improve the operating performance of the HESS. The reference track of the exchanging active power of the supercapacitor is pre‐planned based on wind turbine output, load demand, and the predictive DSEG output. Meanwhile, a linearisation and state of charge (SOC) management strategy for the supercapacitor is proposed to avoid excessive charging‐discharging. During the predictive control process, the DSEG input is continually adjusted by means of rolling optimisation combined with feedback correction until the output of the HESS approximates its expectation. Case studies show that the supercapacitor efficiently eliminates the power hysteresis of the DSEG and the DSEG eliminates the intrinsic error caused by the linearisation of the supercapacitor output in turn, indicating that the control effect of the HESS is improved.