  Uncertainty levels in forecasting of renewable generation and demand are
known to affect the amount of reserve required to operate the power grid with a
given level of reliability. In this paper, we quantify the effects on the
system reserve and reliability, due to the local dispatch of stochastic demand
and renewable generation. The analysis is performed considering the model of
the IEEE 39-bus system, with detailed dynamic models of conventional
generation, wind generation, demand and an under-frequency load shedding
mechanism. The analysis compares to cases: the base case, where renewable
generation and demand power are stochastic and the power reserve is provided by
conventional generation, against the case where the operation of traditionally
stochastic resources is dispatched according to pre-established dispatch plans
thanks to controlling local flexibility. Simulations reproduce the
post-contingency dynamic behavior of the grid due to outages of generators. The
contingencies are selected to trigger under frequency load shedding mechanisms,
hence to demonstrate the different levels of system operation reliability for
the two case studies. Simulation results show that dispatching traditionally
stochastic generation scores better regarding to expected energy not served,
producing an increase of the system reliability.
