Improvement of Voltage Stabilization in a Hybrid Microgrid Supplied by RES by use of Weighted Moving Average Filter

摘要

This paper presents a new method for bus voltage stabilization in a hybrid microgrid supplied by RES (Renewable Power Sources). Upto now, we have presented some experimental study results obtained from a Hybrid Microgrid prototype system, which was developed andinstalled on Tagajo Campus of Tohoku Gakuin University, Japan. In this developed system, major power sources are assumed to be RESsuch as PV and wind power generations, and two kinds of power storage devices of secondary battery and EDLC (Electrical Double LayerCapacitor) are incorporated to cooperatively compensate and stabilize the bus voltage that is degraded by power fluctuation of RESgeneration and load change. For proper control of these power storage devices, which have significantly different charging/dischargingproperties as well as cycle life, cost and size, the measured voltage signal need to be separated into that with different frequencies. So far, aLPF (Low-Pass Filter) has been adopted in our previous researches for realizing this signal separation, however, our experimental studieshave shown that a time delay may occur in some cases and may deteriorate the response of the whole system. Therefore, in this study a newsignal processing method is designed instead of the LPF for the purpose of voltage stabilization improvement, which is called WMAF(Weighted Moving Average Filter) in this paper and worked out based on the weighted moving average formula used in the statistical field.This paper presents the simulation results with microgrid system model that has the same configuration of the developed Hybrid Microgrid,and the improving effect of DC bus voltage stabilization by application of the proposed WMAF is examined. The purpose of this study is toconfirm whether the measured voltage signal can be separated into proper low and high frequency ones appropriately and rapidly by theproposed WMAF method, and moreover, to verify whether the DC bus voltage can be effectively stabilized by the cooperative controlbetween battery and EDLC.