Improvement of on-load tap changer performance in voltage regulation of MV distribution systems with DG units using D-STATCOM

This paper presents a new technique for the voltage regulation of a radial medium voltage (MV) distribution grid in presence of distributed generation (DG) units. The proposed technique consists of the coordinated action of on-load tap changer (OLTC) of transformer and reactive power compensation by D-STATCOM. Managing the system voltage using the action of OLTC is one of the most common ways for voltage regulation of MV systems. However, OLTC cannot be used for voltage regulation of long radial distribution feeders as it changes the sending point voltage of the feeder. In this study, the problem of using OLTC for the voltage regulation of a radial distribution feeder will be solved by using reactive power compensation at the DG connected bus. Simulation results reveal that the proposed control method is capable of maintaining the system voltage within the permitted range in the worst scenarios of the test system.