Dual-timescale generation scheduling with nondeterministic flexiramp including demand response and energy storage

Increased grid-connected wind power generation results in net load with higher volatility as well as larger ramping requirements. It is becoming imperative to provide flexible ramping products (flexiramp) for better generation / load alignment and smoother wind power integration. This paper advocates a non-deterministic flexiramp modeling approach devised in a hybrid stochastic / deterministic dual-timescale framework. The latter uses a day-ahead chance-constrained scheduling formulation along with a deterministic real-time online rolling scheduling model, to facilitate the procurement of flexiramp products in the two timescales. Demand response and energy storage are implemented and quantified as additional flexiramp product. Flexiramp reserve is introduced, to ensure sufficient flexiramp capacity throughout the timescales. To reduce the wear and tear of generators and consider the operational and maintenance costs in the proposed framework, cycling ramping (cycliramp) cost is subsumed as a penalty in the day-ahead objective function. Simulations are carried out for the 24-bus and 118-bus systems. Numerical results highlight the efficacy of the proposed generation scheduling models, along with the impact of contemplating flexiramp and cycliramp cost components in the dual-timescale scheduling approach.