A hierarchical multi-agent evaluation scheme for integrating distributed energy resources in distribution systems

Modern distribution grid is a combination of distributed generators (DGs), energy storage systems, and controllable loads connected to mid-voltage or low-voltage network that can operate in deregulated manners. High penetration of renewable resources at distribution level places new challenges on the planning and economic operation of the distribution systems. This paper proposes a hierarchical control framework based on multi-agent method to allow more flexible control on the distributed energy resources and adjustable loads at the user end while minimizing the computation burden on the distribution grid operator. The impact of large-scale DG integration is evaluated in terms of important factors such as voltage stability and line loading rate. A multi-agent network is structured based on the critical line identification technology for the purpose of reducing the control complexity in the reliable system operation. The developed mechanism coordinates the operation among different generation units and loads. The adjustable DG and loads at the customer side and controllable reactive power devices are deployed to limit the voltage deviation within the acceptable range. Simulation results clearly indicate that the agent-based hierarchical control scheme is effective in distributed energy resources management among multiple clusters of DG and variable load.