Enhanced Transient Response and Power Sharing in Microgrids Using an Adaptive Droop–PID Controller Optimised via PSO–ANN

Abstract

The control of islanded microgrids presents several technical challenges, particularly in terms of achieving solid stability in voltage sharing and high-speed capability amidst fast load variations. Traditional control methods, such as fixed-gain droop control, often fail to address the contradictory requirements for accurate voltage control and balanced power allocation. Aiming to overcome these challenges, this paper introduces an advanced cascade control strategy incorporating the concept of a hybrid outer loop. The key novelty of the proposed approach lies in the integration of a PID controller using the conventional droop control scheme in outer loop. This strategy resolves the static errors and substantially improves system damping. Meanwhile, the inner loop with a fixed PI controller guarantees quick voltage and current decoupling. Aiming to achieve adaptability under varying operational conditions, the system adopts a two-stage particle swarm optimisation (PSO)–artificial neural network (ANN) optimisation technique. Firstly, PSO is employed to compute the globally optimum controller variables, including the PID and droop coefficient gains. An ANN is then used to capture these mapping relationships, enabling the real-time prediction and application of these optimal gains in real-time operation. The efficacy of the proposed controller was assessed using physically symmetric inverters that were operated under challenging 60%/40% asymmetrical power-sharing conditions. Simulation results indicate that the proposed adaptive controller outperforms traditional methods by minimising overshoot and settling time, improving power-sharing ratio and substantially reducing total harmonic distortion.