Power System Reliability Evaluation Considering Operating Reserve Provided By Air Conditioners

With the continuous growth of p eak demand and the increasing penetration of intermittent renewable energy sources in recent years,both the power supply and demand have become highly time-varying,calling for a huge amount of operating reserve in different time scales.Demand side resources(DSRs),especially the air conditioners(ACs),offer an alternative to enhance the system reliability by providing operating reserve with active load reduction during peak periods and during contingencies.One important characteristic of ACs is that they cycle on and off by turns instead of consuming power at a constant value.This makes the dynamic response of ACs different from that of the conventional generating units.However,there is a lack of analytical models to obtain the dynamic response of ACs for the provision of operation reserve,bring complexities in the design of dispatch strategies and power system reliability evaluation.Meanwhile,because of lacking the consideration of dynamic response from ACs,existing control and dispatch strategies of ACs cannot guarantee the flexible provision of required reserve capacity during the required deployment duration.Moreover,the dynamics of operating reserve provided by ACs under uncertainties need to be involved in power system reliability evaluation framework,so that the risk level of the power system can be accurately anticipated.In order to solve the aforementioned difficulties,this paper investigates three aspects,i.e.,analytical model to represent the dynamic response of operating reserve provided by ACs,dispatch strategy of ACs for the flexible provision of operating reserve,and power system reliability evaluation considering the dynamics of operating reserve provided by ACs.Firstly,a three-layer structure is designed to integrate the operating reserve provision into the interactions between aggregators and consumers.In order to avoid the power oscillation resulted form the temporary synchronization of ACs,safe protocol is embedded in the smart controller of an individual AC.On this basis,the dynamic aggregate power of ACs is generated directly from the migration of ACs'room temperature during the reserve deployment process.Secondly,an evaluation framework of operating reserves is presented to quantify the effect of the lead-lag rebound on the capacity dimension and time dimension.Then,an optimal sequential dispatch and recovery strategy of ACs is designed to mitigate the lead-lag rebound and thus realize the flexible control of the duration time from minutes to several hours.In this way,the dispatchable potential of ACs can be fully utilized in power system operation.Lastly,considering the stochastic consumers'behavior and ambient temperature,the property of cumulants is applied to obtain the probabilistic distribution functions of reserve capacity provided by ACs.On this basis,multi-state model of operating reserve provided by ACs is constructed.Lz-transform approach is utilized to integrate the multi-state model of hybrid generation and operating reserve providers for the power system reliability evaluation.In this manner,the particular dynamics of operating reserve provided by ACs(e.g.,the demand response rebound)can be accurately involved in the power system reliability evaluation,which therefore provide reference for decision making in power systems.