Reactive Power and Voltage Control Issues Associated with Large Penetration of Distributed Energy Resources in Power Systems

As the penetration of distributed energy resources increases and large conventional generators are retired, voltage regulation of generators and reactive power control of the power system should be considered more carefully. In this paper, the impacts of adding renewable resources and changing generators’ voltage regulating buses on static power flow convergence and voltage profiles are studied and reactive power status of critical areas as well as online and offline reactive power reserve capacities are visualized. The results show that if renewable resources are added without adding sufficient reactive power resources or if the voltage regulating bus of all generators move to the low voltage side of step-up transformers without tuning the voltage set points of generations, voltage violations and even voltage collapse may occur, which have a negative impact on the reliability of the power system. The paper also reviews possible solutions such as tuning the voltage set points of generators for reactive power management and adding voltage control devices such as switched shunts or static var compensators (SVCs) to the grid to compensate for this change.