Optimization and Energy Management of a Microgrid Based on Frequency Communications

In recent years, a transition towards a more sustainable future has started and it is imperative that this trend continues. An increasing energy demand from the continuously growing population, together with the increment of greenhouse gasses (GHG) emissions and the depletion of fossil fuels have motivated the penetration of renewable energy systems (RESs) in different areas and scales. As a consequence, the energy sector is facing a transition from a centralized network, composed of large and controllable power plants, to a decentralized grid based on RESs. Within this framework, microgrids (MGs) provide a key solution to integrate RESs, controllable energy resources, flexible loads and storage systems either in a grid-connected or an islanded mode. Optimal energy management is crucial to develop strategies to improve the efficiency and reliability ofMGs, as well as newcommunication networks to support optimal and reliable operation. This study proposes an energy management system (EMS) whose main objective is to optimally operate a microgrid (MG) using frequency as the only communication signal. The developed model considers renewable energy sources (RESs) such as photovoltaic (PV) panels and wind turbines, a micro-generator, a battery energy storage system (BESS) and both critical and controllable loads. In a conventional grid with a control system based on frequency communications, each element of the grid has a droop curve and the frequency reflects the generation - load balance as a result of a compromise between each other. However, in the inertia-less grid proposed in this thesis the EMS controls the BESS and solves the optimization problem, which determines the optimal frequency of the system. The rest of the system components react according to the optimal frequency by following their specific frequencypower response curves. In thisway, an optimal planning and operation of theMGis sought in order to minimize operational costs and consequently increase the use of RESs, reduce GHG emissions, perform a smart charge of the BESS and optimally operate the diesel generator. A demand-side management (DSM) mechanism is introduced in order to manage controllable loads via load-shedding to match availability of RESs. To further adjust generation to load demand, RESs curtailment or supply-side management (SSM) is implemented through the application of a version of an available standard that ensures grid security when connecting RES generators to the grid. The performance of the proposed EMS will be validated through simulation results for different scenarios using real numerical data from an existing microgrid, comparing the results against the traditional control system.Electrical Engineering, Mathematics and Computer ScienceElectrical Sustainable EnergyDC systems, Energy conversion & Storag