Study On The Theory And Implementation Method Of The Differential Planning Of Power System

In recent years, all kinds of extreme weather and rare natural disasters occurred one after another in our country, which was a serious threat to safe operation of power grid. In the event of large area blackout accident, it would seriously affect the progress of national economy construction, and it even caused the confusion of people’s life order. In order to reduce the adverse impacts of meteorological disasters on the security and stability of power grid, power grid enterprises generally took preventive measures, improved the standards of power grid construction from the planning and design stage. However, the distribution of power and load in our country presented reverse, the grid that took the risk of resource optimization configuration had the characteristics as follows, the span of the space was large, the geographical conditions across the region were complex, and the difference of weather was obvious. If the protection standards of power grid were improved comprehensively and indistinguishably, it couldn’t ensure that the resistance of grid against natural disasters was improved economically, efficiently, and reasonably. Therefore, according to the characteristics and development of power grid in our country, the specific application of differentiation in power grid planning of our country were delved into, the theory and implementation method of large power grid planning were studied, which had important theoretical value and practical significance.The dissertation reviewed a large number of domestic and foreign literatures, and combined a number of scientific research projects. The theory and implementation method of the differential planning of power system were studied deeply and systematically. The main contents were as follows:The relevant theoretical basis of differential planning was introduced in this dissertation. The research trend of power grid planning, evaluation method of power system, the construction and search of core backbone network frame, and the impact of meteorological disaster on power system were reviewed and analyzed. On the basis of analyzing the characteristics of differential planning, the key problems needed to solve of differential planning were put forward, which were how to build and search the core backbone network frame and strengthen lines differentially considering meteorological conditions.From the key technology of core backbone network frame construction, the evaluation method of component importance based on the theory of risk and uncertainty was elaborated. It was used to determine the importance of the line and the node, and the evaluation results of component importance were also used as the basis of weight selection for survivability index. Based on the theory of network survivability, from the point of view of electrical characteristics and network characteristics, the network survivability evaluation index system was set up by recoverability, security, connectivity and resistibility. It could evaluate the survivability of network as well as lay a foundation for the construction of mathematical model of the core backbone network frame.A method of constructing core backbone grid with the target of the smallest total line length and the largest integrated survivability index based on survivability index system was put forward. The cosine migration model, the premature judgment mechanism, and the mutative scale of chaos and cauchy mutation strategy were introduced into the improved BBO optimization algorithm in order to improve the convergence speed and convergence precision of the algorithm. The graph theory and improved BBO optimization algorithm were used to search for core backbone network frame, and then the core backbone network frame scheme was finally determined. Numerical example results verified the rationality of the proposed model and the superiority of search algorithm.A method of strengthening lines differentially based on line comprehensive fault rate and economic assessment was put forward for the obtained core backbone network frame scheme. The generalized theory of extreme value was introduced to model the ice history data of region, and then the probability of the region’s ice damage under a given thickness of ice was obtained. Combining with the model of line fuzzy failure rate when the line was under stress, the model of line comprehensive fault rate was established under certain condition of ice. Comprehensive failure rate was used to calculate differentiated ’impairment’ benefit, on the basis of which economy evaluation indexes of differential planning were established. In that case, the differential strengthening scheme of lines of core backbone grid were determined.The demands and principles of differential planning are summarized. The system and implementation method of differential planning was proposed to guide the actual implementation of differential planning scheme of the actual power grid. The data analysis of actual power grid was made based on the principles of differential planning and the evaluation results of component importance to determine the important power supply, circuit and load needed to be safeguarded. The core backbone network frame was constructed according to the demands and features of differential planning and as well as its survivability index system. The method of strengthening lines differentially based on line comprehensive fault rate and economic assessment was used to determine the strengthening level of lines of core backbone grid. The final scheme of the differential planning of power system was obtained. The differential planning of the actual power grid showed the applicability and effectiveness of the proposed method.