Research On Optimal Dispatching Of Active Distribution Networks With Multi-Source Coordination

With the increasing penetration rate of distributed power such as wind power and photovoltaic power in the distribution network,the randomness and intermittent output characteristics have a negative impact on the optimal operation of distribution network.At the same time,due to the access of distributed generation(DG),the traditional single-supply radial distribution network structure has become a multi-power complex network,and the distribution network power flow has also changed.To cope with this change,energy storage technology is introduced into the distribution network and works in conjunction with DGs to achieve the controllability of DGs,so as to reduce the impact of the distributed power output on the safe operation of the distribution network.In the process of transforming the traditional distribution network from passive to active,the focus and difficulty of the research is how to give full play to the role of wind power,photovoltaic and other renewable energy sources.Therefore,this paper mainly studies the multi-source coordination optimization problem of active distribution network.The contents and the achievements of this paper are as follows.In order to study the power flow of active distribution network,this paper presents the mathematical model of DG,energy storage unit,microgrid,flexible load,SVC and on-load tap-changer in distribution network.Based on this,the power of active distribution network is calculated,which lays the foundation for the proposed control strategy and optimal scheduling method.Using wind-storage system to achieve the access of wind power grid.Based on the hierarchical control theory,the control strategy of preferentially absorbing wind power in active distribution network is proposed.Based on this strategy,an optimal scheduling model of active distribution network is established.The model combines the multi-time scale optimal dispatching model with the hierarchical control theory.In the constraints of the dispatching model,the output characteristics of the wind power storage combined system are considered,and the reserve capacity is limited by the opportunistic constraints.The model is solved using improved particle swarm optimization.The simulation of the improved IEEE-33 node system proves that this method can effectively improve the utilization of wind power in the active distribution network and greatly reduce the negetive impact of wind power randomness on the optimal dispatching in active distribution network,and it can improve the stability of the distribution network operation.Based on the linear branch power flow equations and mixed integer linear programming,a multi-time scale optimization model is proposed.First,the linear branch power flow of distribution network is introduced,and the main elements in ADN are modeled,meanwhile,the linearization method is used to simplify the non-linear components.Then,the day-ahead dispatch model is established by considering the active and reactive power coordination.In addition,in order to reduce the influence of the stochastic power from DG and FL on dispatch results,taking the results of day-ahead dispatch as reference,an auxiliary short-term dispatch model is also constructed to maximize the consumption of wind and photovoltaic power.Through the simulation of IEEE-33 node system,it is proved that this method can greatly improve the solution speed,can reduce the pressure of the main network optimization dispatching to a certain extent.