Energy Management of a Microgrid: Compensating for the Difference between the Real and Predicted Output Power of Photovoltaics

© 2016 IEEE. An increasing awareness of energy efficiency has led to the development of several improved converter topologies, semiconductor devices and control schemes for distributed energy resources, and, particularly, for microgrids. Recent advances in energy management systems (EMS) for microgrids have improved upon existing methods in several aspects, including prediction of power generated by photovoltaics (PV), and optimal management of electrical energy storage. However, the actual generated PV power may deviate from predictions for several reasons, such as rapid cloud changes or system faults. This paper contributes to the ongoing research on EMS control schemes by proposing a model predictive control (MPC) scheme that adapts to the difference between the actual and predicted output power of PV. The key benefit of this approach is its ability to rapidly adapt to varying operating conditions of the PV without increasing the computational burden of a typical MPC scheme. The feasibility of the scheme is demonstrated using simulations of 5 kW microgrid system compromising a 5 kW/400 Ah battery, 10 kW PV and 5 kW grid/load connection. The proposed scheme reduces variations in the state of charge (SOC) of a battery. The proposed scheme also reduces the energy taken from grid and this improvement in performance is a function of the difference between the actual and the predicted power.