  In autonomous microgrids frequency regulation (FR) is a critical issue,
especially with a high level of penetration of the photovoltaic (PV)
generation. In this study, a novel virtual synchronous generator (VSG) control
for PV generation was introduced to provide frequency support without energy
storage. PV generation reserve a part of the active power in accordance with
the pre-defined power versus voltage curve. Based on the similarities of the
synchronous generator power-angle characteristic curve and the PV array
characteristic curve, PV voltage Vpv can be analogized to the power angle
{\delta}. An emulated governor (droop control) and the swing equation control
is designed and applied to the DC-DC converter. PV voltage deviation is
subsequently generated and the pre-defined power versus voltage curve is
modified to provide the primary frequency and inertia support. A simulation
model of an autonomous microgrid with PV, storage, and diesel generator was
built. The feasibility and effectiveness of the proposed VSG strategy are
examined under different operating conditions.
