Reactive power and voltage control in distribution systems with photovoltaic generation

This paper presents the interaction of traditional centralized voltage regulators such as load-tap-changing (LTC) transformers with the new emerging inverter-based distributed photovoltaic (PV) generators in reactive power and voltage control of distribution systems. Different reactive power control strategies for inverter-based PVs are considered and their interaction with LTC transformers is analyzed. The investigated objective function is the total electric losses for the 24 hours while satisfying the system operational constraints. Discrete Particle swarm optimization (DPSO) is used to determine the LTC operation scheme as an integer nonlinear optimization problem. The performance is validated by applying the proposed method to the standard IEEE 33 bus test system.