摘要
With increasing adoption of intermittent renewable generation,challenges to maintain stable frequencies for power systems are increasing.Demand-side resources,such as thermostatically controlled loads(TCLs),have been proven capable of providing regulation services.The district cooling system(DCS),a type of centralized TCL that provides cooling services for a group of buildings,is an ideal resource for this purpose.A DCS usually has significant regulation flexibility because its rated power capacity is large(up to 100 MW)and it can utilize thermal inertia of an aggregation of buildings.However,as a large-scale system with complex thermal dynamics,its effective regulation is nontrivial,and its traditional demanddriven control scheme has difficulty considering regulation signals from power systems.To address these challenges,we propose a bidirectional-driven control scheme in a DCS for the first time.On this basis,we formulate the thermal and electricity model of a DCS in the frequency domain and derive an equivalent model to control it like a traditional generator.Furthermore,we propose a sensitivity-based control strategy for a DCS to allocate mass flow adjustments among buildings,which effectively considers heterogeneity of buildings to balance temperature impacts.Numerical studies illustrate effectiveness of the proposed model and control strategy.
