Frequency Droop-Based Synchronverter Without Battery for Primary Support of Microgrids

Distributed generation (DG) based on synchronverter with no battery is unable to provide frequency support without compromising DC-bus voltage level. However, this paper proposes a new synchronverter, which can outline this limitation by adjusting the DC-bus voltage setpoint if the grid frequency gets out of a safe predefined range. This is done through a droop mechanism as long as the DC-bus voltage level is inside range. Similarly, if the grid voltage gets out of a scheduled range, a voltage droop is triggered to provide voltage support. Thus, the proposed synchronverter brings support capability with no battery and maintains a safe DC-bus voltage level. Performance is assessed in an eolic-photovoltaic hybrid DG in a microgrid. The obtained results demonstrate the primary support capability with no battery and prolonged support capability if a battery is instead used in DC bus.