| At present, China has been increasing its investment on the constructions of electricity systems year by year. And the capacity integrated into grid of large-scale and new power units has become larger and larger. Therefore, the complexity between the power grids has become higher, the operating situations has become more complex and the real-time control has become more difficulty. Meanwhile, affected by the changeable external environment, the operating pressure and the accident probability increases. Therefore, it is critically needed for security to assess power grid operation trends accurately, rapidly and roundly in a short time.At present the research about evaluation methods of the operating status of the power grid has been relatively mature, but it only focuses on the current operating section rather than the future trend, and cannot meet the scheduling requirements; Although research on risk evaluation analyzes the future operating trend of power grid, it is hard to meet the double demands of comprehensiveness and speed because it will cause a large amount of calculation to ensure the comprehensiveness of calculation. So online calculation has poor applicability.Focusing on the online real-time operating trend evaluation and based on the status index system, this paper adopts the methodology of grasping the main contradiction and the main problem, and proposes a two-step grid operation real-time operating trend security evaluation method that combines preliminary evaluation and refined calculation. Through preliminary evaluation, the operating trends of internal factors of the power grid and the entire power grid will be obtained quickly, satisfying the speed requirement of the online calculation; and through refined calculation, the concrete area that needs calculating and the specific dangerous side will obtained, guaranteeing the completeness of the trend evaluation. The specific method of its idea is:First, take the preliminary evaluation to divide the power grid into several interconnected sub regions, which are divided into generation side, transmission side and load side according to the functions, and calculate the importance of the load side according to related factors. Then calculate the importance of the inner elements with the tide tracing method according to the relevance of the generation side, transmission side and load side, then combine with the fuzzy theory to predict the trend of each internal element after impact events, finally, use the trend of internal elements and the operation of the important degree to compose the operating trend of the entire network. Refined calculation divides the trend of internal elements into three danger classes based on the results of preliminary estimation and constructed hold value of the degree of risk, and obtaining the level of trend of internal elements respectively. Specifically, the most dangerous and the safest status elements don’t need to calculate the indicator, and respectively conduct emergent control and no control. For non-urgent and unsafe status elements, it is need to confirm and calculate the specific danger indicator by using the proposed status indicator system.During calculating the internal elements of importance, the paper measure the importance degree of the load side through the economic effects and social effects which caused by load loss, and apply the analytic hierarchy process to calculate the importance degree of the electricity side that takes into account the economic factors and social factors; Based on importance degree of the electricity side, taking the supply and transport relationship of used electric power on the load side as a link, associating importance degree of the electricity side with generation side and transmission side, and solving the importance of the generation side and transmission side using power flow tracing method.Finally, the paper uses the provincial power grid operation section as example to prove validity and feasibility of the proposed method. |
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