Multi-state operating reserve model of aggregate thermostatically-controlled-loads for power system short-term reliability evaluation.

Highlights • TCLs' dynamic response for providing operating reserve is modelled analytically. • A probabilistic model of operating reserve provided by TCLs is proposed. • A multi-state reliability model of operating reserve provided by TCLs is developed. • The power system short-term reliability is evaluated based on L Z -transform approach. • TCLs accounts for 5.9% of peak demand in a typical large city can enhance power system reliability by 18%. Abstract Thermostatically-controlled-loads (TCLs) have been regarded as a good candidate for maintaining the power system reliability by providing operating reserve. The short-term reliability evaluation of power systems, which is essential for power system operators in decision making to secure the system real time balancing, calls for the accurate modelling of operating reserve provided by TCLs. However, the particular characteristics of TCLs make their dynamic response different from the traditional generating units, resulting in difficulties to accurately represent the reliability of operating reserve provided by TCLs with conventional reliability model. This paper proposes a novel multi-state reliability model of operating reserve provided by TCLs considering their dynamic response during the reserve deployment process. An analytical model for characterizing dynamics of operating reserve provided by TCLs is firstly developed based on the migration of TCLs' room temperature within the temperature hysteresis band. Then, considering the stochastic consumers' behaviour and ambient temperature, the probability distribution functions of reserve capacity provided by TCLs are obtained by cumulants. On this basis, the states of reserve capacity and the corresponding probabilities at each time instant are obtained for representing the reliability of operating reserve provided by TCLs in the L Z -transform approach. Case studies are conducted to validate the proposed technique. [ABSTRACT FROM AUTHOR]