The Robustness Degree Evaluation Of Distribution Grid Operation Process

Electric power has become the one of the main driving force of economic development of countries in the world, The rapid development of our national economy put forward higher requirements for the current distribution grid. China State Grid Corp proposes building the strong and smart grid to meet the high requirements and high standard of the development of the national economy for the power system. As the end link of distribution network is directly connected with the power user plays an important role in the power system, the construction of the strong and smart grid must build a strong distribution network. Some problems such as which distribution network is strong distribution network and how to evaluate the distribution network must be solved in the construction of the strong and smart grid.Firstly, the concept of distribution network structure robustness degree is defined, the basic theory is expounded and the evaluation process is determined in this paper. Power supply margin is selected as evaluation index according to the selection principle of evaluation indexes. Fuzzy set and membership function is used to describe quantitative fuzzy concept such as "distribution network structure robustness degree".Secondly, the calculation method of branch power margin is proposed based on the power flow calculation. Load with time-varying characteristics in the distribution network, in order to ensure that the calculated margin index is more accurate and consistent with the actual situation, the load growth mode of each load node must be considered when calculating the branch power margin. The method proposed in this paper not only determines the node load growth mode by the forecasting curve of short term load change, but also refers various constraint conditions easily when calculating power flow.Finally, the method of how to put the branch power margin into the index of distribution network is introduced. Through the analysis of the example, the feasibility and availability of the method proposed in this paper is verified.