Adaptive notch filter based WECS for unbalance mitigation

Abstract

The accelerating spread of distributed energy resources among the LV networks has revealed their adverse impact on voltage profiles, power quality and protections along the network. On the contrary, since they are essentially interfaced with the network through power electronic converters that can be exploited to enhance power quality. Voltage regulation, unbalance and harmonics mitigation are some examples of the functions that can be implemented through these converters. This paper presents a wind energy conversion system (WECS) with a back-to-back converter performing its mere function of maximizing wind energy capture and regulating output active and reactive power. Added to these basic functions, ancillary services are provided to a local load and MV grid. Voltage regulation of the load voltage at different loading conditions is achieved. Extraction of load unbalance is investigated through different algorithms. Adaptive Notch Filter (ANF) has demonstrated a leading response over the conventional methods in detecting the symmetrical components under different unbalance conditions. Unbalance in grid currents is then effectively managed and the currents from/to the MV grid are ensured to be balanced. The system is simulated using PSCAD/EMTDC and results are presented to confirm validity of the proposed methods.