Cloud-Edge-Collaboration-Based Flexibility Scheduling Strategy Considering Communication and Computation Delay

As the penetration rate of renewable energy sources (RES) gradually increases, demand-side resources (DSR) should be fully utilized to provide flexibility and rapidly respond to real-time power supply-demand imbalance. However, scheduling a large number of DSR clusters will inevitably bring unbearable transmission delay, and computation delay, which in turn lead to lower response speeds. This paper examines flexibility scheduling of DSR clusters within a smart distribution network (SDN) in view of both kinds of delay. Building upon a SDN model, maximum schedulable flexibility of DSR clusters is first quantified. Then, a flexibility response curve is analyzed to reflect the effect of delay on flexibility scheduling. Aiming at reducing flexibility shortage brought by delay, we propose a modified flexibility scheduling strategy based on cloud-edge collaboration. Compared with traditional strategy, centralized optimization is replaced by distributed optimization to consider both economic efficiency and effect of delay. Besides, an offloading strategy is also formulated to decide optimal edge nodes and corresponding wired paths for edge computations. In a case study, we evaluate scheduled flexibility, operational cost, average delay and the chosen edge nodes for edge computations with traditional strategy and our proposed strategy. Evaluation results show the proposed strategy can significantly reduce the effect of delay on flexibility scheduling, and guarantee the optimality of operational cost to some extent.