Operation Risk Assessment And Early Warning Of Active Distribution Network Based On Complex Network Theory

The growing permeability of distributed resources in distribution network makes the contribution of active distribution network(ADN)an inevitable trend in the development of smart grid.Compared with the traditional distribution network,ADN will have more access of the distributed generators,energy storage systems,controllable load and electric vehicles,which will make ADN have higher parameter uncertainty and topological diversity.The deeper combination of primary and secondary side also raises a higher requirement for the accuracy and rapidity of the operation risk assessment.Based on complex network theory,this paper studies the operation risk and its algorithm of ADN mathematically and physically.Current status of ADN,the application of complex network theory in power grid and advantages and disadvantages of different kinds of operation risk assessment algorithm are first investigated,based on which the main sources and key elements of risk assessment of ADN are analysed.A novel index for ADN operation risk evaluation is proposed based on complex network theory.Based on this index,rapid assessment of multistage operation risk and classified early warning of ADN can be realized.Then,strengths and limitations of the traditional complex network theory indicators applied are analysed based on physical model.Through theoretical derivation,new indexes named as network flow transfer distribution factor and betweenness-like are proposed,which are improved form of former ones.Combining complex network theory index and sequence theory index,this paper proposes a new concept called sequence-betweenness as well,based on which node and line vulnerability analysis can be more accurate,thus helping lower operation risk while distribution resources connecting power grid.By serializing risk index,customized assessment can be realized under different scenarios,load importance and key elements.In the last of this paper,ADN operation risk assessment and early warning system is established,which provides a more accurate reference for reducing the operation risk of ADN from distributed resource access point selection,network connection mode selection,operation parameter control and so on.IEEE33 node distribution network power system example results show the applicability of the model and the effectiveness of the method.