With the ever-intensive utilization of distributed generators (DGs) and smart devices, distribution networks are evolving from a hierarchal structure to a distributed structure, which imposes significant challenges to network operators in system dispatch. A distributed energy-management method for a networked microgrid (NM) is proposed to coordinate a large number of DGs for maintaining secure and economic operations in the electricity-market environment. A second-order conic programming model is used to formulate the energy-management problem of an NM. Network decomposition was first carried out, and then a distributed solution for the established optimization model through invoking alternating-direction method of multipliers (ADMM). A modified IEEE 33-bus power system was finally utilized to demonstrate the performance of distributed energy management in an NM.Energies 2018, 11, 2555 2 of 18 for implementing the control center as well as communication infrastructures [3,4]. Furthermore, storing all data in one control center carries the risk of exposing the privacy of customers, as well as unavoidable single-point failures [3]. More importantly, the distributed method is more computationally efficient than the centralized one. Therefore, it is desirable to effectively coordinate NMs in a distributed manner for improving reliability and economics.
Literature ReviewConventionally, a distribution-level microgrid is centrally controlled by a central coordination center [5]. More specifically, the central coordination center collects relevant information from dispersed controllable devices and forecasting data to perform an optimal dispatch of distributed resources for the next period [6]. Centralized energy-management architecture has been widely studied in existing publications. Reference [7] proposed a two-layer energy-management model wherein the schedule level attains the economic-operation scheme based on forecasts, while the dispatch level dispatches controllable DGs based on real-time data. In Reference [8], a centralized scheduling algorithm was proposed for an electric vehicle-dominated microgrid to optimize the charging scheme considering the charging cost and convenience of microgrid users. In Reference [9], the centralized energy-management problem for a household-level microgrid was formulated as a utility-maximization problem, subject to capacity constraints. In Reference [10], a centralized energy-management optimization model was formulated for a residential-quarter microgrid including a concentrating solar-power unit with an objective of minimizing the involved operation costs. A two-stage stochastic demand-side management model for a commercial-building microgrid is formulated in Reference [11], considering the uncertainties in solar-generation outputs, loads, microgrid availabilities, and microgrid energy demands.The fully distributed optimization method includes two broad categories, i.e., the Lagrangian relaxation-based and the optimality-condition decomposition-based category. The Lagrangian r...