Ancillary Services Prioritization in Inverters with Virtual Synchronous Generator Functionalities.

The massive integration of renewable energy reduces the overall inertia of the grid deteriorating the system stability. Virtual synchronous generator approaches have been recently introduced in the inverter controller to enable distributed resources to improve the power system stability through frequency support. At the same time, ancillary services can be provided by the inverters to compensate reactive power flow and loading asymmetries, improving in this way the efficiency and utilization of distribution grids. This work proposes a novel multifunctional inverter where the virtual synchronous generator mode for frequency support is combined with ancillary services provision capabilities for phase balancing and reactive power compensation. In this context, an algorithm is proposed to prioritize online the provision of each functionality in order to guarantee the overcurrent limits of the inverter under any operating conditions. The inverter performance is validated through simulations, indicating that it can be reliably used to improve the power system operation.