Electromechanical dynamic analysis for powertrain of off-grid switched-reluctance wind turbine hydrogen production system

Abstract

Research on hydrogen production from wind power is important for improving wind energy utilization and hydrogen production efficiency; however, research on switched-reluctance hydrogen production from wind power has been relatively limited, and its system operation characteristics are unclear. Therefore, it is necessary to conduct research on the electromechanical coupling characteristics of switched-reluctance wind turbine hydrogen production systems (WTHPSs). An electromechanical dynamic model was established for the powertrain of an off-grid switched-reluctance WTHPS, including wind turbine, gear transmission system, switched-reluctance generator (SRG), and hydrogen production devices (HPDs). The model considers the detailed characteristics of the gear system, the nonlinear physical details of the HPD, and the electromagnetic characteristics of the generator. An improved control strategy was also developed for the SRG to reduce torque fluctuation. The steady- and transient-state electromechanical characteristics were simulated and analyzed, and the influences of the SRG control strategy and HPD switching on the system dynamic characteristics and hydrogen production rate were investigated. First, with respect to the improved SRG control strategy, the results show that SRG torque fluctuation can be reduced. The influence of the SRG electromagnetic torque on the transmission system gradually decreases from the high-speed stage to the low-speed stage. However, for a sudden decrease in wind speed, the SRG with the improved control strategy tracks the reference speed more slowly. Second, with respect to the hydrogen production rate, almost no difference can be observed between the two SRG control strategies. Single and multiple HPDs have a slight effect on the dynamic characteristics of the system when the HPDs can consume all the generated power. The production rate of HPDs in a parallel connection is higher than that with a single device at the same power, and the difference increases with an increase in power.