A Fully Decentralized Optimal Dispatch Scheme for an AC–DC Hybrid Distribution Network Formed by Flexible Interconnected Distribution Station Areas

Abstract

Due to unbalanced load growth among different regions and the increasing integration of distributed generators (DGs), distribution station areas (DSAs) currently face issues such as voltage violations, curtailment of renewable energy generation, and imbalanced load rates among DSAs. Interconnecting DSAs to form an AC–DC hybrid distribution network (DN) can not only address the aforementioned problems but also provides more efficient interfaces for DC devices. In order to coordinate the controllable devices within the flexible interconnected DSAs and achieve an optimal operational state, centralized optimal dispatch strategies are mainly used, which requires the deployment of an additional central controller and entails heavy communication and computation burdens. To overcome the drawbacks of centralized dispatch, a fully decentralized optimal dispatch scheme based on the alternating direction method of multipliers (ADMM) is proposed. Based on the network partitioning results, the introduction of auxiliary variables that replicate the coupling variables between areas further eliminates the need for a coordinating center in the standard ADMM, achieving a fully decentralized optimal dispatch. Additionally, two network partitioning methods are proposed for implementing decentralized dispatch. Both partitioning methods can achieve the goals of load rate balance and voltage profile improvement when implementing decentralized dispatch. Their key distinction lies in their effectiveness in improving the voltage profiles on the DC side. The partitioning method that treats the entire DC side as a separate area, resulting in higher investment, achieves better results in improving the DC voltage profiles than the other one. The choice of partitioning method can be based on practical engineering requirements.