  Renewable energy technologies including solar and wind inevitably play a
leading role in meeting the growing demand for a decarbonized and clean power
grid. However, these technologies are highly dependent of meteorological
conditions of power plant site and the challenge remains on how to cope with
their short-term and momentarily variability. This paper presents a
hierarchical control system to provide ancillary services from a solar PV power
plant to the grid without the need for additional non-solar resources. With
coordinated management of each inverter in the system, the control system
commands the power plant to proactively curtail a fraction of its instantaneous
maximum power potential, which gives the plant enough headroom to ramp up or
down power production from the overall power plant, for a service such as
regulation reserve, even under changing cloud cover conditions. A case study
from a site in Hawaii with one-second resolution solar irradiance data is used
to verify the efficacy of the proposed control system. The algorithm is
subsequently compared with an alternative control technology from the
literature, the grouping control algorithm; the results show that the proposed
hierarchical control system is over 10 times more effective in reducing
generator mileage to support power fluctuations from solar PV power plants.
