The Dynamic Voltage Restorer (DVR) is an equipment works based on power electronic devices which has been applied to protect the sensitive loads against voltage disturbance. This equipment is one of the instruments in Custom Power Park (CPP) which uses Distributed Generation (DG) source connected to DC bus to compensate the voltage sag of sensitive loads. Combined operation of DVR with DG unit connected to DC bus is a new method which is proposed in this paper. Another equipment of CPP are Active Power Filter (APF) and Static Transfer Switch (STS) devices. APF has been used to eliminate the harmonics of non-linear loads. The STS was applied to increase the reliability of critical load against the system faults. In this paper, the ability of CPP for power quality improvements has been simulated and modeled by PSCAD/EMTDC. Results of simulation show that voltage sag and interruption has been improved by the DVR.