Reduce operational costs of thermal power units in power systems using the flexibility of district cooling systems

Abstract

The high volatility of wind generation causes the thermal power units to start up and shut down frequently because there is a lack of flexibility in the power systems, which poses a challenge to economic operation. With the increase in cooling demand, district cooling systems (DCSs) have received attention in recent years and have been built in many regions, which offer a novel option to alleviate the above problems by utilizing the complementarity between power and cooling systems. In a typical DCS, the cooling source is a key component that generates cooling energy for the entire cooling system. Utilization of the cooling storage capacity of cooling sources in DCSs is an economical and efficient measure for more operational flexibility of power systems. Therefore, this paper proposes a unit commitment model with combined power systems and DCSs to reduce the operational costs of thermal power units and wind curtailment. In this model, an accurate model of a cooling source with an ice storage tank, where the cooling characteristics and energy transmission process are reflected, is built to fully excavate the flexibility potential of DCSs. Finally, numerical simulations are performed to show that the proposed method reduces the operational costs by 15.78% within a scheduling day and makes the wind curtailment close to zero. The results of the above comparison demonstrate that the method can improve the operational economy and encourage wind power integration while assuring an adequate supply of electricity and cooling.