Optimal fractional-order PID controller of inverter-based power plants for power systems LFO damping

Abstract

The penetration of inverter-based power plants (IBPPs), such as large-scale photovoltaic (PV) power plants(LPPPs), is ever increasing considering the merits of renewable energy power plants (REPPs). Given that IBPPs areadded to power systems or replaced by conventional power plants, they should undertake the most common tasks ofsynchronous generators. The low-frequency oscillation (LFO) damping through the power system stabilizers (PSSs)of synchronous generators is regarded as one of the common tasks in power plants. This paper proposes an optimalfractional-order proportional-integral-derivative (FOPID) controller implemented in the control loop of IBPPs for LFOdamping in power systems. For this purpose, the last version of the generic dynamic model for renewable technologies(GDMRT) is used, which was released by the Western Electricity Coordinating Council (WECC) and Electric PowerResearch Institute (EPRI). In addition, an LPPP is studied as a case study. The FOPID controller is optimallytuned using the particle swarm optimization (PSO) algorithm in order to produce effective LFO damping. Finally, theperformance of this controller is simulated and investigated in a two-area test system, showing the better performance ofthe LPPP for LFO damping by using the proposed optimal FOPID controller compared to the optimal lead-lag controllerand optimal PID controller.