Stochastic Economic Dispatch of Integrated Transmission and Distribution Networks Using Distributed Approximate Dynamic Programming

With lots of distributed renewable generators and storage devices integrated into distribution networks, the coordinate economic dispatch (ED) between transmission and distribution networks is needed. A stochastic ED algorithm based on distributed approximate dynamic programming for integrated transmission and distribution networks considering the uncertain renewable generator outputs is proposed. First, the convex power flow models of transmission and distribution networks are proposed. Then, the reservoir levels of pumped-storage hydro stations and the remaining stored electric energy of battery storage stations are deemed as the storage quantities, while the renewable generator outputs are deemed as the exogenous stochastic variables to establish the stochastic storage model for the stochastic ED problem of integrated transmission and distribution networks. The approximate value functions represented by the sum of the piecewise linear functions of the storage quantities are constructed to decouple the multiperiod ED problem into a series of single-period ED problems. Finally, by using the alternating direction method of multipliers, each single-period ED problem of integrated transmission and distribution networks is solved in a distributed manner among transmission and distribution networks. Test results on the modified T6D7 system and a practical Shenzhen city network demonstrate the correctness and efficiency of the proposed algorithm.