Flexible power point tracking for active frequency regulation in grid-connected photovoltaic power plants

The increasing penetration of photovoltaic (PV) systems into modern power grids necessitates advanced control strategies capable of supporting grid stability. Traditional PV systems rely on Maximum Power Point Tracking (MPPT) to maximize energy extraction, limiting their ability to participate in grid-support functions such as frequency regulation or power curtailment. This paper presents a flexible power point tracking (FPPT) control strategy that enables PV systems to operate at arbitrary points along the power–voltage (P–V) curve. A multi-mode power management scheme is proposed, integrating conventional Perturb and Observe (P&O) MPPT with FPPT, allowing the system to switch dynamically between energy maximization and power-limiting modes based on real-time conditions. Simulation studies on a three-phase, double-stage grid-connected PV system demonstrate the controller's ability to maintain stable operation, ensure smooth transitions between modes, and inject high-quality current into the grid. The results confirm the viability of the proposed approach as a foundation for enabling PV plants to contribute to grid frequency control and other advanced power management functions.