Demand response with load-block shifting in the day ahead scheduling of predominantly hydro systems: Impact on the large-scale Brazilian case

Operational planning and scheduling of electrical systems aims to meet the system load in the most economical way, managing not only the risk of load curtailment but also to ensure ramping capability. Flexibility is also pursued by exploring the large penetration of variable renewable generation such as wind/solar plants. Demand response (DR) programs have emerged as an alternative to accommodate such variability by stimulating or paying customers to curtail or shift their load, yielding a reduction in peak prices and smoother hourly price curves. Even though the advantages of DR for originally pure thermal systems have been widely shown in the literature, quantification of the effects of DR optimization in predominantly hydro systems is yet to be better explored, since such systems already have a large flexibility in operation. We present a mixed integer linear programming application of DR with load-block shifting for the day ahead scheduling model of predominantly hydro systems, based on the official model that is used to dispatch and set system hourly prices for the Brazilian system. The model comprises load curtailment based on price offer by consumers, as well as load-block shifting, which consists in a more precise representation of loads that have time-shifting flexibility but not load profile flexibility. We show that the performance of the model is computationally feasible and assess its impact on marginal/total operation costs. We also evaluate some aspects such as: competition among offers and optimal bidding points from the customer´s point of view. Results are presented for the IEEE 14-bus system and the actual Brazilian hydrothermal-wind system.