Research On Dispatching Method Of Multi-microgrid In Distribution Network

As a new production and distribution mode of electric power,microgrid combines distribution generation,energy storage system and load,so that the distribution network doesn’t have to face large-scale renewable energy.With the development of technology and the advancement of electricity market reform,multi-microgrid system may be connected to the local distribution network in the future.It is of great significance to the development of microgrid to coordinate the flow of power between different units by using reasonable and effective dispatching method,so that the microgrid and distribution network could maintain a good operation state.A grid-friendly optimal dispatching method is proposed in this paper for the multimicrogrid system in distribution network.Firstly,the day-ahead optimal dispatching strategy of the distribution network layer is put forward,which coordinates the interactive power between microgrids and distribution network,so as to improve the operation state of the distribution network and the acceptance willingness and absorption level for renewable energy.By constructing the comparison matrix,the multi-objective optimization model is transformed into a single-objective optimization model.The flower pollination algorithm with strong global search ability is selected and improved to solve the optimal dispatching model of distribution network layer.Simulation examples verify the feasibility of distribution network layer optimal dispatching strategy and the effectiveness of modified flower pollination algorithm.Secondly,the day-ahead optimal dispatching strategy of microgrid layer is put forward.Because microgrids and distribution network belong to different operating subjects,a dynamic electricity price adjustment mechanism is proposed.According to the optimal result of distribution network dispatching layer,the mechanism guide the microgrid to make production plan of distribution generation and energy storage system in the next day and give the microgrid a certain degree of operational autonomy.The stepwise power distribution model is constructed,and the energy storage systems in different microgrid share the total unbalanced power of the multi-microgrid system,which makes the energy storage systems maintain good dispatching ability.Simulation examples analyze the influence of dynamic electricity price adjustment mechanism on the dispatching process,and verifies the effect of the day-ahead optimal dispatching strategy and the stepwise power distribution model.Finally,the intraday optimal dispatching strategy is proposed,which uses hybrid energy storage system to make up for the deviation of the day-ahead dispatching plan caused by the uncertainty of renewable energy.The power decomposition model is established.According to the characteristics of energy storage equipment,the charging and discharging power of hybrid energy storage system is distributed to storage batteries and super capacitors by variational mode decomposition method.Variational mode decomposition method causes the problem of the reverse charge and discharge state between different energy storage equipment at the same time,so the power correction model based on three spline interpolation is constructed to improve it.Simulation examples prove that the power distribution meets the requirements,and the charge and discharge state of these two equipments are consistent after the correction.