  The deepening penetration of renewables in power systems has contributed to
the increasing needs for generation scheduling flexibility. Specifically, for
short-term operations, flexibility here indicates that sufficient ramp
capacities should be reserved to respond to the expected changes in the load
and intermittent generation, also covering a certain amount of their
uncertainty. To address the growing requirements for flexible ramp capacity,
markets for ramp products have been launched in practice such as the ones in
California ISO and Midcontinent ISO. Some-times, to guarantee sufficient ramp
capacity, expensive fast start units have to be committed in real-time.
Moreover, with higher penetration of renewable generation, the flexibility
provided by the conventional units might not be enough. Actually, wind power
producers are physically capable of offering flexibility, which is sometimes
also economically efficient to the entire system. In this paper, we aim to
explore the mechanism and possibility of including wind power producers as ramp
providers to increase the supply of flexibility. To conduct the anal-yses, a
two-stage stochastic real-time unit commitment model considering ramp capacity
adequacy is formulated. Case studies indicate that both the system and the wind
power producers can benefit if the wind power is allowed to provide flexible
ramp products.
