A robust frequency estimator for single-phase microgrid applications

Abstract

This paper presents a novel approach for estimation of single-phase grid frequency under adverse distorted conditions for single-phase microgrid application. In the existing literature, frequency estimation based on Zero Crossing Detector (ZCD) has good dynamic performance. However, the method is sensitive to noise and results in high steady state error under harmonic conditions. Sliding Discrete Fourier Transform based Zero Crossing Detector (SDFT-ZCD), on the other hand, has excellent harmonic rejection capability with less steady state error but suffers under transient conditions. In view of above said advantages and disadvantages of both, ZCD and SDFT-ZCD, a Hybrid Frequency Estimation (HFE) method is proposed for frequency estimation. The proposed HFE is based on Modified ZCD and modulated SDFT-ZCD. As a result of which, a very good steady state and dynamic response with immunity to transients is achieved. The effectiveness of the proposed approach is established with numerous simulation studies.