This paper presents an enhanced centralized voltage control method of on-load tap changer (OLTC) and step voltage regulators (SVRs) in distribution systems with photovoltaic (PV) and evaluates its effectiveness. A conventional centralized voltage control is effective when its data acquisition period is short because tap operations of OLTC and SVRs are performed after the voltage values in the distribution lines are acquired. However, in distribution systems with high penetration rate of PVs, voltage deviation occurs between the data acquisition intervals because the tap positions can be changed only at the timing when the data are acquired. The proposed centralized voltage control method forecasts voltage fluctuation between the data acquisition intervals and changes to the tap position which maximizes the minimum voltage margin from the voltage limits. The numerical simulation results will be shown to compare the voltage control effectiveness of the proposed method with that of the conventional method.