基于储能Soc日前计划的微电网实时能量优化调度方法

Real-time energy optimal dispatch for microgrid based on day-ahead scheduling of charge state

针对微电网实时优化调度计算的工程需要,提出了一种遵循储能Soc日前计划的基于网流模型的微电网实时能量优化调度方法。该方法以尽量遵循储能Soc日前计划为前提,首先建立以"等效供电成本"最小为目标函数,以分布式电源出力、储能单元储能水平以及微网与主网交互功率均在限值之内和微网内功率平衡为约束条件的实时优化数学模型;随后提出将该非线性优化模型转换为最小费用最大流网流模型进行线性化求解的方法。算例表明,遵循储能Soc日前计划的实时调度计划能够对上级电网起到削峰填谷的作用,无论在并网运行还是孤岛运行模式下能够有效降低微电网供电成本,日供电成本降低达30%以上,该方法能够足实时优化调度计算的工程要求。

Recently, as an effective method of using distributed power generation, microgrid has been developed rapidly. The microgrid's safe and economic operation has been paid more and more attentions. Microgrid economic operation cannot goes well without perfect energy optimization scheduling. Microgrid energy optimization scheduling is based on the distributed power generation forecasting and load forecasting, aiming at making full use of energy storage unit, coordinating microgrid internal power supply and the power/energy flow between microgrid and large power grid and maximizing the microgrid economic benefits. In current literature, the dynamic optimization model and static optimization model can’t combine the day-ahead scheduling with real-time scheduling and fail to make full use of the storage and removal effect of energy storage unit. In order to meet the project needs for real-time optimal dispatch of microgrid, in this paper, we proposed a real-time optimal dispatch model for microgrid based on the state of charge of day-ahead scheduling, and the network flow model. In this method, based on the real-time super short power generation/consumption prediction data, we developed methods to follow the state of charge of day-ahead scheduling, the future 5-15 minutes state of charge, charge and discharge power, the micro power supply, and power output planning. Firstly, the model took minimum equivalent power supply cost as the goal, it put four parts as constraint conditions: the controllable micro powers output, storage level, the interaction power between microgrid and power grid, and the power balance of microgrid. Then, based on the minimum cost and maximum flow theory, the nonlinear model was converted into a network flow model that can be solved linearly. In this theory, a directed topology network had been constructed. Three kinds of nodes existed in the network: 1) two virtual nodes: an original node and an terminal node; 2) four power output nodes: renewable energy generation output node, discharge power of grid node, discharge power of energy storage node, and controlled micropower supply output node; and 3) three power input nodes: load node, charge power of grid node and charge power of energy storage node. The arcsof directed topology were divided into three subsets. They were 1) four power output arc,from original node to power output nodes; 2) ten mutual power arc, from power output nodes to power input nodes; and 3) three power collection arc, from power input nodes to terminal node. Finally an example of microgrid was given, using the optimization model and algorithm which were proposed in this paper. The optimization scheduling results of grid-connected operation model and island operation model showed that by reasonable control of state of charge in each period, the given optimization scheme can maximize utilization of renewable energy power and minimize power supply cost of microgrid.