Research On Optimal Operation Strategy Of Smart Distribution Network In Multi-time Scale

With the access of a large number of flexible resources such as distributed power supply,energy storage equipment,soft open point,and electric vehicles,the distribution network has better observability and controllability,which can flexibly change the operation topology.Hence it is called the smart distribution network.Coordination active operation on different flexible resources for distribution network has a vital role in the economic efficiency and safety.Several time-scales including long-time,day-ahead and real time are covered.The paper puts forward an optimal operation strategy of smart distribution network under multiple time scales considering grid structure,day-ahead active power plan and real-time reactive power control.In the long-time scale,the grid optimization strategy considering reliability constraints is put forward in view of the topology structure of distribution network.Firstly,the economic reconfiguration model of distribution network is established based on the branch flow equation and transformed into mixed integer second-order cone programming.At the same time,the reliability constraints of node power supply are set based on the line correlation matrix and transformed into a linear model based on the disjunctive programming.considering the uncertainty of distribution network load curve,a two-stage robust reconstruction model was built by means of the robust optimization of multiple discrete scenarios.Finally,according to the constraint generation algorithm,the long-term operation topology of the distribution network is obtained.Simulation results show that the proposed topology optimization method takes into account the reliability of important nodes,economy and robustness of distribution network.In the day-ahead and intra-day scales,an economic dispatching strategy considering flexible load regulation capacity is proposed to optimize the active power of the distribution network.Firstly,the flexible resources in the distribution network are set as the generalized energy storage equipment model.And the economic dispatching model of the distribution network is established considering its flexible regulation ability.In the day-ahead stage,the market guiding model and the demand response model according to marginal electricity price of nodes is established based on master-slave game and dual cone programming.In the intra-day stage,a distributed scheduling mode is proposed.And the parallel optimal scheduling of flexible resources is realized by means of Benders decomposition.The simulation results show that the proposed economic dispatching model can reduce the peak-valley difference and the power cost of the distribution network.In the real-time scale,aiming at the voltage and reactive power optimization of intelligent distribution network,a real-time voltage and reactive power control strategy based on two-stage optimization is proposed.Firstly,based on rolling optimization,the optimization model of reference point for distribution network operation is established,which takes into account the action loss of discrete devices such as on load tap changer and voltage controller.Furthermore,the power flow equation is linearized based on the power flow operation point,and the real-time voltage and reactive power control model based on the linearized power flow equation is obtained.The simulation results show that the proposed real-time voltage and reactive power control strategy can coordinate a variety of voltage and reactive power control equipment,achieve minute level voltage control,effectively reduce the voltage deviation rate of load nodes in distribution network,and avoid frequent action of equipment.