New control strategies based on Grid-Forming converters make possible the operation of isolated microgrids without the support of synchronous generation. This paper proposes an Energy Management System algorithm that optimizes the operation of a microgrid, maximizing the integration of renewable energy and considering the possibility of disconnecting all synchronous generators. The algorithm is applied to a microgrid modelled with real data and two economic dispatch strategies are analysed: the first requires keeping at least one synchronous generator connected to provide frequency regulation following standard practice; and the second considers the disconnection of all conventional generation relying on the capabilities of Grid-Forming converters when sufficient reserve is available. The results show that the proposed strategy reduces the operational cost of the system, as well as solar PV curtailment and diesel consumption.

This paper proposes a two-step optimization algorithm for energy management and optimal control of activereactive power commands in microgrids. The first step ensures an optimal energy management and provides the active power setpoints for power plants and energy storage. The second step calculates the voltage setpoints for power plants and reactive power flows whilst minimizing power transmission losses. This work focuses on the second step of the algorithm and the framework to combine both. A previous study introduces the first step based on a receding-horizon scheme. It is analysed and discussed the performance of the algorithm against two decentralized methods widely used in the literature. The results show that the proposed algorithm reduces power transmission losses by more than 20% compared to other methods.

This paper presents a Voltage Source Converter (VSC) with an implemented Virtual Synchronous Machine (VSM) control strategy, which is able to work in both grid-tied and islanded mode, providing inertia to the grid and regulating the frequency and the voltage of the system. Those capabilities are necessary to make possible a high penetration of power electronic converters in the power grid. Converters work in parallel with the conventional generators while being able to deal with islanding or some other critical grid events. The proposed control strategy has been tested in a test bench with a synchronous generator (SG). When islanding the VSC, the converter demonstrates its grid forming capabilities controlling the frequency and voltage of the microgrid. The VSM control has proved its grid forming and grid supporting capabilities, without switching between control modes, making it ideal to react to different grid events and showing a soft transition between grid-tied and islanded operation modes.