Research On Distributed Optimization Method For Dynamic Economic Dispatch Of Microgrids

As an effective management mode of distributed generation, microgrid has important significance to promote the development of clean energy, increase the penetration of new energy in distribution network, and improve the reliability and economy of power supply. However, the traditional centralized dynamic economic dispatch optimization methods are facing challenges because of different characteristics of all kinds of distributed energy resources, the insufficient capacity of network communication, the limited information collection capacity of distributed energy resources and the need to protect private data for generation units. Therefore, it has a great theoretical meaning and engineering value to study the distributed optimization of dynamic economic dispatch problem of microgrids.For the distributed dynamic economic dispatch problem of an islanded microgrid, we build its distributed dynamic economic dispatch model by considering the diesel power generations cost, disposal costs of renewable energy generations, depreciation expense of energy storage devices and active power loss of the power network as a complex objective function, and generating units and storages are divided into several areas based on their access positions of the power network where the common branches between two areas are defined as their boundary. Also, the synchronous alternating direction of multipliers method is used to solve this distributed model. This distributed algorithm does not require coordination center to updateand broadcast global Lagrange multipliers, each area only exchanges the voltage angles at the boundary buses with its adjacent regions during iterations, and sub optimization problems of all areas can be solvedin parallel. Furthermore, we have tested the correctness and effectiveness of this distributed algorithm, taking a real microgrid as a test system.For distributed dynamic economic dispatch problem of a distribution network containing multiple microgrids, microgrids work in a grid-connected mode and can exchange the power with a distribution network, which is different from an islanded mode. The distribution network can not only purchase the electricity from the main grid, but also can buy and sell the electricity to microgrids, and the power price in peak, valley and flat time also needs to be considered during the dispatch period. By considering the cost of microgrids, the active power loss and power purchase cost of a distribution network as a complex objective function, we build the distributed dynamic economic dispatch model. In this model, the partition is done according to the access location of microgrids and the distributed energy resources. Thus, the synchronous alternating direction of multipliers algorithm is still used to solve this distributed optimization problem. In addition, the comparison between the distributed algorithm and the centralized algorithm shows that the proposed algorithm can converge to the same optimal solution as the centralized optimization, taking a distribution network with two microgrids as a test system.