Research On Energy Management Strategy Of Active Distribution Network For Improving New Renewable Energy Harvesting

In response to the global environmental crisis and energy exhaustion,the renewable energy resources represented by solar energy and wind energy have been rapidly developed.China's renewable energy installed capacity is far ahead in the world at present.However,solar energy and wind energy in some areas are abandoned due to the lack of space for local consumption and the limit of capacity for outgoing channel.In the meantime,the power of solar energy and wind energy,which is intermittent and random due to the influence of natural factors,may impact the power grid and affect the safe and stable operation of the power grid when its scale is large enough.The higher requirement has been put forward for the energy management and optimization scheduling of the active distribution network.Hence,in order to make full use of the renewable energy and guarantee economic and stable operation of distribution network,it is necessary to make the proper energy management strategy when the large-scale high permeability renewable energy is access to active distribution network.The thesis mainly studies the energy management strategy of active distribution network with the objective of improving the usage rate of the renewable energy.The main works and specific researches are summarized as follows:Firstly,the energy management of active distribution network is studied in space scale and time scale because of the space and time difference in different distributed generation.In space scale,the same owner of the distributed generations is divided into one area.The distributed energy scheduling mechanism is formulated based on the local usage of the renewable energy of two grade joint mechanism of regional distribution network and active distribution network and global coordinating optimization.In time scale,the day-ahead and intraday energy management of active distribution network is formulated.The distribution network operates optimally through the coordinated dispatching in space scale and time scale.Secondly,the day-ahead and intraday optimal model of regional distribution network and active distribution network is established.In the day-ahead optimal model of regional distribution network,the model which considers the economic and environmental benefits and effective availability of the renewable energy is a multi-objective optimization model with minimum operating cost and maximum usage rate of renewable energy.In the day-ahead optimal model of active distribution network,the model is also a multi-objective optimization model with minimum voltage deviation and network loss.Intra-day optimization takes the daily power schedule at the corresponding dispatching time as the state value,and takes the minimum of regional distribution network adjustment costs as the optimization goal.The power balance and optimizing operation in regional distribution network is realized with adjusting the active power of controllable distributed generation,energy storage,and interruptible load.The energy management center of active distribution network decides if the intraday dispatching should be used by evaluating the optimized results in regional distribution networks and if the power perturbation in distribution network leads the node voltage.Finally,the multi-objective optimization model is solved in the modified 33 nodes distribution system and real distribution system with the non-dominant genetic algorithm.The result shows that the energy management of active distribution network can increase the usage rate of local renewable energy effectively,reduce the power of regional distribution network to higher grid and ensure the economic operation of control areas.At the same time,the power flow of renewable energy can be decreased,the operating efficiency of distribution network can be increased and the voltage quality can be ensured with the help of dispatching the energy storage and demand side load.