Optimal Reactive Power or VAR Flow from Distributed Smart PV Inverters

Abstract

Nowadays, smart photovoltaic (PV) inverters can perform advanced functionalities e.g., volt-var, volt-watt, frequency-watt, power curtailment controls which can support the voltage and frequency adjustment for an electric power grid. In order to maintain the voltage within the allowable region, the voltage regulator, FACTS devices, capacitor is used to provide reactive power or Var to the power grid. Smart PV inverters can provide the reactive power or Var to control voltage for a power grid using volt-var control command. The control signal of smart PV inverters may send over the cloud to generate Var requirement, but it needs to send a large number of control signals to several inverters at a time. It increases network congestion, and probability for missing commands. Therefore, an optimal switching command signal is important that will reduce total number of switching for inverters, the network congestion, and total control commands to inject Var for a distribution power network. This paper proposed an optimal reactive power or Var flow strategy from a bunch of smart PV inverters. The proposed method reduces the total numbers of switching commands for smart PV inverters, and consequently decreases the control commands, network congestion, and missing commands.