Power flow analysis for islanded microgrid in hierarchical structure of control system using optimal control theory

Abstract

In environmental uncertainties, the power flow problem in islanded microgrid (MG) becomes complex and non-trivial. The optimal power flow (OPL) problem is described in this paper by using the energy balance between the power generation and load demand. The paper also presents the hierarchical control structure which consists of primary, secondary, tertiary, and emergency controls. Clearly, optimal power flow (OPL) which implements a distributed tertiary control in hierarchical control. MG consists of diesel engine generator (DEG), wind turbine generator (WTG), and photovoltaic (PV) power. In the control system considered, operation planning is realized based on profiles such that the MG, load, wind and photovoltaic power must be forecasted in short-period, meanwhile the dispatch source (i.e., DEG) needs to be scheduled. The aim of the control problem is to find the dispatch output power by minimizing the total cost of energy that leads to the Hamilton-Jacobi-Bellman equation. Experimental results are presented, showing the effectiveness of optimal control such that the generation allows demand profile.