Wavelet entropy and its application for flicker contribution evaluation

Abstract

As a result of the integration of various new load types and generation units into electric power systems, power quality disturbances such as sag–swell, harmonics, inter‐harmonics, and flicker have come into focus in the last decades. Among these disturbances, flicker is one of the serious power quality issues for both power system operators and users. In addition to having direct effects on human life such as the discomfort caused by visual disturbance, flicker may cause incorrect operations of electrical devices. Furthermore, finding a dominant flicker source in order to mitigate it and supply high‐quality power to users are the main tasks of network operators. The measurement of the flicker level is defined in the IEC 61000‐4‐15 standard as measured by a flicker meter; however, it deals only with voltage signals and is not sufficient to understand the contribution of the load and background power systems separately. Therefore, this paper proposes new approaches to the evaluation of flicker characteristics using simulated and real signals. The novelty of this paper is that it investigates the flicker characteristics in the light of multi‐resolution wavelet analysis and information‐theory‐based wavelet energy entropy analysis together and proposes a new index to interpret flickers' responsibility in load and flicker source detection. The proposed method uses only voltage and current signals and does not require additional calculation of any network parameter such as the system impedance. The proposed method is validated by simulations as well as site measurements, and the results show the accuracy and suitability of the proposed method. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.