| Power system reliability assessment can provide the reference for power system planning and operation from the perspective of probabilistic risk.If the electrical connection system(ECS)is considered in this reliability assessment,the scale of power grid will grow,as well as the complexity of reliability calculation.But without the influence of ECS,the calculation results will become more optimistic,so the reliability assessment of bulk power system considering the influence of ECS can provide a standard reference for ECS planning.On the other hand,with the promotion of renewable energy generation,as a new form of it with great potential for power generation,large scale wind power has been integrated into power grid.It's necessary to establish a reliability model for wind power system and analyze the composite influence of wind power integration,which has great importance in power grid for future planning from the perspective of theoretical and practical application.From the point of view of power system topology,this paper studies the influence of collection system of wind farm and bulk power system within large-scale wind power integrated in power grid.The main contents of this paper are as follows:Besides the failure of wind turbine generator(WTG)in wind farm,outage and fault status of ECS components,the different electrical collector systems(ECS)topologies,the disconnection and switching operation of switch components will all effect the output energy of wind farms as well.Based on the multiple states of wind farm ECS components and the structure features of ECS,this paper can not only consider the multi-failure of WTG and ECS components,but also consider the disconnection and switching processes of switch components of wind power system.Based on the nonparametric kernel density estimation method and considering the influence of the ECS on wind power system,a reliability assessment model is established.Four different wind farm ECSs are implemented by using this proposed model,and the validity is verified by case studies,which provides references for the planning of wind farm ECS topologies.In bulk power grid containing wind farms,if the random characteristics of ECS components are considered directly,the sampling process of all components in bulk system and the system states analysis will reduce the efficiency of reliability calculation.While the random characteristics of wind farm ECS faults can be described by the probability density distribution model based on the nonparametric kernel density estimation.Then the wind farm output energy can be obtained using this model through sampling,which can reduce the complexity of the power system with wind energy integration and improve the efficiency of power system reliability evaluation.The function states of ECS elements will influence the system network structure,and this influence will be considered in bulk power system with wind farm integration in this paper.According to the network graph theory,the network topology is identified,and the transmission line outage,loss of load and the bus section splitting operation caused by ECS faults will also be considered.Then combine with the wind power output model,a reliability evaluation model of bulk power system containing wind farm considering the influence of ECS can be established.The effectiveness of this method is verified by different case studies,which provide a reference for the planning of wind power integration.Besides,this paper further considers the different forms of ECS of other conventional substations,then the improved ECS structure of RBTS and IEEE-RTS79 system are designed and evaluated by this model,which provide a standard reference value for bulk power assessment without considering the influence of ECS. |
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