An Instantaneous Current Control Strategy and Its Digital Implementation for PWM Converter in Variable-Speed WECS

Within various topologies of variable-speed wind turbine systems, PWM converters are employed either as grid interface or as motor dive or both. According to the particular requirements for dynamic response of MPPT and utility grid connection, a real-time control strategy adopting instantaneous current regulation with ac-side voltage feedforward correction is proposed. The mathematical model of the system with neutral line suitable for the method is given and the dc voltage control and compensation are also devised. The digital implementation makes it feasible in practical wind energy conversion systems (WECS) and the experimental results are provided demonstrating the satisfactory dynamics of currents and effective restriction for lower order harmonics.