A coordinated AGC-RTEM-P2P frequency control strategy using fractional-order controllers for low-inertia power systems

The increasing integration of renewable energy sources has significantly decreased the effective inertia of modern power systems, thereby weakening their ability to regulate frequency. Traditional Automatic Generation Control (AGC) strategies are becoming increasingly inadequate in handling rapid frequency dynamics and stability issues, especially in the presence of communication delays. This paper proposes a novel three-layer coordinated frequency control strategy, named AGC-RTEM-P2P, which incorporates fractional-order control, a hierarchical system architecture, and delay compensation techniques. Central to the approach is a fractional-order proportional-integral-derivative (FOPID) controller, which supports a multi-timescale control framework consisting of the AGC layer, the real-time energy market (RTEM) layer, and the peer-to-peer (P2P) coordination layer. Communication delays are effectively addressed using Padé approximation and Recursive Least Squares (RLS) estimation. Control parameters are globally optimized using the lightning search algorithm (LSA). Simulation studies conducted on the IEEE 118-bus system show that the proposed strategy outperforms conventional methods by reducing frequency deviations, enhancing system stability margins, and lowering control energy consumption.