Development of three-phase unbalanced power flow using local control of connected photovoltaic systems

With the increased number of installations of distributed photovoltaic (PV) systems within electricity distribution systems, power flow analysis is required to handle multiple PV systems. At present, PV systems are equipped with a local control function (LCF). The conventional algorithm is then applied for power flow analysis with the LCF of each PV system, where the power output of LCF of each PV system is calculated and used in the power flow calculation. The conventional algorithm is terminated when the voltage at each iteration of the power flow algorithm is converged. However, the conventional algorithm inevitably requires a lengthy calculation. This paper proposes a power flow algorithm that applies the Newton-Raphson technique to handle multiple PV systems with an LCF for a faster calculation. The LCF is approximated to have a continuous characteristic. The developed power flow algorithm can be used for a three-phase unbalanced distribution system and its effectiveness was demonstrated in a modified 19-node distribution system. (c) 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.