Hierarchical economic control of air-conditioning loads to compensate for fluctuations in distributed photovoltaic generation

Abstract

Flexible loads such as air-conditioning loads (ACLs) can be directly controlled as demand response resources (DRRs) to provide ancillary services to the power grid. This paper proposes a hierarchical economic control strategy for the transmission system operator (TSO) to utilize ACLs to compensate for fluctuations in distributed photovoltaic (PV) generation with maximum control profit considering the uncertainties. The ACLs are aggregated by load aggregators (LAs) and controlled as two kinds of virtual generators in each LA with an additional power generation (APG) function to provide DRRs as a whole. To achieve the unification of planning and execution, an allocation algorithm and a control method for ACLs are respectively put forward to distribute the required DRRs among LAs and regulate ACLs in each LA. The proposed hierarchical economic control strategy realizes the decision-making process of purchasing DRRs through day-ahead scheduling and real-time control. In day-ahead scheduling, a flexible optimization interval division approach is presented to obtain the distribution of optimization intervals, and a stochastic optimization model is formulated to obtain the optimal purchased DRR capacity considering the PV/load forecasting errors. In real-time control, after determining the distribution of optimization intervals and the sampling points that adopt the APG function, the additional DRR capacity that needs to be purchased in real time is further optimized based on the day-ahead scheduling results. Simulation results demonstrate the effectiveness of the proposed control strategy.