Growing numbers of utilities are experiencing proliferation of Plug-in Electric Vehicles (PEV) and Photovoltaic Distributed Generation (PV-DG) in their distribution systems. Charging patterns of PEVs tend to increase the original day-time and evening peak demands of distribution feeders, while PV-DG units are highly intermittent energy sources. Therefore, the integration of large amount of PEVs and PV-DGs represents a significant challenge for distribution planning and operations. As an emerging technology, Distributed Energy Storage (DES) is a promising alternative to improve the reliability and efficiency of distribution systems. DES serves as an energy buffer to manage demand and supply fluctuations. Through proper control algorithms, DES has the potential to facilitate the integration of both, PEVs and PV-DG units. Previous works have studied the mitigation of steady state impacts of PEVs and PV-DG units by using DES systems. However, this topic has not been fully investigated from a dynamic analysis perspective. This paper discusses the utilization of DES to alleviate dynamic impacts of PEVs and PV-DG units on power distribution systems. This alternative is analyzed by using models of PV-DGs, PEV and DES developed in PSCAD. Results of dynamic simulations, including voltage profiles at critical points on a test distribution feeder and operations of Load Tap Changer (LTC) are presented and discussed. Simulation results show the potential of DES for improving dynamic performance of distribution feeders with PEVs and PV-DGs proliferation.