Grid-connected photovoltaic (PV) systems with relatively high capacity effectively reduce peak load, but because of their reverse power flow, they can cause overvoltage along a feeder that can exceed five percent of the rated voltage. Modern PV systems with the capability of Volt/Var control can mitigate overvoltage by either injecting or absorbing reactive power. Thus, the objectives of this study are to (1) model a distribution network (feeder J1 located in the northeastern United States and enhanced by thirteen PV systems) using OpenDSS; (2) use actual collected load profile data as input data to the simulation model and PV generation output data at 15-minute intervals; and (3) calculate the time-series steady-state power flow of the distribution network when PV systems generate or absorb reactive power. Finally, it addresses overvoltage resulting from the deployment of high-capacity grid-connected renewable PV systems and mitigation techniques for such overvoltage issues, particularly Volt/Var management and control. Index Terms--Photovoltaic (PV) systems, time-series steady-state power flow, and Volt/Var.

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Various distributed generation (DG) systems with capacities in the range of several kilowatts to tens of megawatts can increase voltage along a feeder when they are injecting power into distribution systems. Thus, the main objective of this study is to analyze the transient behavior of such a distribution system integrated by DG systems. This study (1) models the IEEE 37-bus test feeder as a distribution network enhanced by DG systems in Simulink of MATLAB; (2) proposes case studies of DG systems with their total capacity of 10 and 38 percent of the feeder rating; and then (3) simulates the transient behavior of the test feeder when DG systems inject active power at the unity power factor during a few cycles of 60 Hz. Finally, it addresses the issues of an increase in voltage resulting from the installation of DG systems in a transient state. Index Terms--Distributed generation (DG), transient behavior of a distribution network, and an increase in voltage

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