Optimized multivariable control structures for voltage regulation in active distribution networks

Abstract The increasing penetration of distributed energy resources (DERs) into Active Distribution Networks (ADNs) demands innovative control solutions to address critical challenges such as voltage stability and power quality. Existing decentralized control strategies often fail to handle the intricate interactions between control loops in highly coupled systems, leading to suboptimal performance, excessive reactive power requirements, and operational limitations. This paper introduces a novel multivariable control framework designed for voltage regulation in ADNs. The proposed framework incorporates advanced Control Allocation and Measurement Combination modules, developed through a systematic methodology that merges Process Systems Engineering and Power Systems principles. By formulating the control design as a bilevel mixed-integer nonlinear programming (BMINLP) optimization problem, the framework minimizes voltage deviations, reactive power usage, and the reliance on actuators and sensors, ensuring system stability even under extreme conditions such as significant active power generation drops. Dynamic simulations performed on the IEEE 33-bus system demonstrate that the proposed approach outperforms traditional decentralized controllers by effectively preventing reactive power saturation and delivering superior voltage regulation. The results indicate that the voltage at all nodes stays within the permissible limits, with a maximum deviation of 0.7 %. Moreover, it achieves these results with reduced hardware and fewer control loops, highlighting its resource efficiency. This work represents a significant step forward in the control of ADNs with high DER penetration. By addressing the limitations of conventional strategies, it offers a scalable and robust solution that optimizes control resources, enhances system stability, and supports the transition to decentralized, renewable-powered distribution networks.