Flexibility contribution of heat ventilation and air conditioning loads in a multi‐stage robust unit commitment with non‐deterministic variability‐oriented ramp reserves

Abstract

Aside from conventional generation units, heat ventilation and air-conditioning (HVAC) loads, thanks to their inherent thermal capacity storage, are reasonable alternatives to mitigate short-term variability impacts in power systems with high renewable energy sources (RES). Accordingly, HVAC loads are integrated into a multi-stage multi-resolution robust unit commitment considering non-deterministic variability-oriented reserves to address operational flexibility requirement in power systems. Since common two-stage robust optimisations are over-conservative, non-causal and in general NP-hard, a non-conservative extended affinely adjustable robust optimisation approach is proposed to provide causality, enhance computational tractability and improve optimality in a multi-stage robust decision-making framework. In addition, since existing hourly resolution scheduling is unable to track fast and frequent variations in RES, the proposed framework is multi-resolution including both hourly and sub-hourly resolutions. Moreover, unlike conventional deterministic flexible ramp reserve procurement, a robust variability-oriented reserve scheduling is presented to determine adequate while economic and technically deliverable flexible ramp reserves from both generation and demand sides. The effectiveness of the proposed model is illustrated on the IEEE 24-bus reliability test system.