Dynamic Simulation of a Large Power System with High-Capacity Photovoltaic Systems Able to Control Reactive Power

Abstract

Relatively small-capacity distributed or clustered photovoltaic (PV) systems change dynamic behaviors of the feeder despite their small capacity. Moreover, modern distributed generation (DG) inverters can control reactive power (i.e., Volt/Var control and management). To connect higher capacity PV systems (i.e., above 50 percent of the total feeder rating) able to control reactive power, various steady-state, transient behaviors, and short-circuit currents affected by the PV systems should be examined in an actual power grid. Thus, the objective of this study is to examine feeder dynamics affected by such a high-capacity PV system able to control reactive power. For this purpose, this study initially models an actual large power grid with thousands of nodes in DIgSILENT, adds high-capacity PV systems (i.e., 50 percent of the feeder rating) with a Volt/Var droop controller to the grid, and generates switching events (i.e.., the circuit breaker on/of) and faults. The Volt/Var control of a high-capacity PV system could mitigate an increase in overvoltage and affect the post-fault voltage because of controlling reactive power. The case study results can be used for the smooth integration of high-capacity DG systems to the grid.