Volt-Var Control for Utility-Scale Solar PV Plants to Downsize SVCs and Curtailment Effects

Abstract

One way to increase solar photovoltaic penetration in the grid is the management of voltage fluctuations. This is because a photovoltaic plant cannot be interconnected to the grid if it causes voltage violations. Voltage violation is where voltage exceeds the acceptable range. Often, grid operators request photovoltaic plant owners to regulate voltage sufficiently with expensive and space-consuming static Var compensators. Unfortunately, this sometimes makes the project less feasible. This paper argues that there are better ways to regulate voltage. It also asserts that these ways must be sought before blindly procuring a static Var compensator or seeking battery storage. We simulated with a 70-MW photovoltaic plant as an addition to the grid. Without voltage regulation, voltage violations in Spring were found to be particularly significant. However, the proposed reactive power compensation removed all voltage violations smartly. Furthermore, the study results demonstrated that the operator-induced curtailment effectively reduced the necessary amount of reactive power compensation, leading to a smaller size of SVC, as it occurred specifically at certain overvoltage points. This paper argues that the economic and spatial efficiency of reactive power compensation devices is key to increasing photovoltaic penetration. It argues that one-sided bearing of the cost of reactive compensation devices is inefficient.