Scheme Reserch And Optimal Assessment Of Urban Power Grid Black-start

With the continuous development of economic progress, power system load demand is also gradually increasing. Meanwhile, the increasing capacity and scale of various regional power grids make the interconnections among the systems becoming more frequent, which have brought a great test to the security and stability of power system operation. As the last defense line of the power system security and stability, studies on black-start have being concerned for a wide range of domestic and foreign scholars.Power system black-start, is a complex multi-objective, multi-period, multi-portfolio, multi-constrained nonlinear optimization problem. After blackout occurred, whether to select the optimal formulation and restoration scheme in accordance with the actual situation in power system quickly and efficiently decides the success or failure of the system restoration to a large extent. The paper aims at researching theory and algorithms with aspects to black-start plans, with a view to improve the success rate of black-start and improve the efficiency of the system restoration and to provide theory and decision support to dispatchers.The main contributions of this thesis are as follows:(1) The key factors which influence the process of black-start have been made into deeply exploration. Considering all possible black-start modes, analyzing and comparing their black-start conditions, restoration strategy and restoration mode, the concept and algorithm of the Generalized Assessment of Black-Start Modes are proposed. A number of indexes are extracted from four aspects of timing, structural, economic and reliability evaluation, and sorting level of black-start modes has been acquired by data envelopment analysis/analytic hierarchy process method (DEA/AHP). The application instance of the southwest zone of Shenzhen power grid shows that this method is effective, which could gain the efficiency sequence of black-start modes, in the mean time, it could obtain the corresponding restoration strategy using in each black-start mode and the optimal choice of power plant to be started under specific modes. This mehod could be a useful aid for dispatchers to choose the most suitable mode scientifically and effectively.(2) In view of the most common strategy of Build-Upward and the corresponding division of regions in the current power grid, a Tabu Search based algorithm for dividing subsystems is proposed in this paper. This method bases on the integrated weights of several indexes values to establish the target function, then determines which subsystems the nodes should be classified into by using the optimal solution of Tabu Search algorithm. The results of application instance indicate that this method could efficiently divide power grid into subsystems under black-start, obtain the optimal division results containing important plants, stations and loads, with high values in practical applications.(3) Restoration of initial subsystem of black-start is related to the success or failure of entire black-start process. On the basis of existing Data Envelopment Analysis approach (DEA), the following method, Group Standard Method (GSM), is proposed to assess the initial black-start paths, which could obtain the effective sequence of black-start paths under determinate conditions. Aiming at the indeterminate elements and the real situation of decision-making in black-start course, Fuzzy Data Envelopment Analysis (FDEA), Fuzzy multi-attribute group decision-making method are proposed to assess the relative efficiency of initial paths of black-start respectively. Thereafter, the instance of the same actual power grid is selected to assess the relative efficiency of the each scheme. The results indicate that the application and optimization of above-mentioned methods under different circumstances could remedy the disadvantage of each single method and could obtain the optimal plan of initial black-start path more effectively. (4) An expert system for black-start plans establishment is introduced from the perspective of specific applications, the form and the acquisition of the knowledge, generation and application of the rules, the composition of the database as well as the generation of the reasoning mechanism for black-start plans are analyzed in particular,the corresponding implementation using the Prolog language is given, then black-start steps are achieved by the application of expert system in the actual grid. The expert system could be used to establish black-start schemes off-line. With the adjusting of the documents of BPA, it could establish the reserved plans corresponding to all kinds of assumed failures, so that it meets the case of the recent establishing mode of black-start schemes.(5) Aiming at the deficiency of the method"Calculated off-line, matched in real time"of current black-start method, the application mode of power grid system in the black-start has been stated, and the algorithm on the early start path assessment is changed into distributed parallel optimization, the real-time monitoring of the partition of power grid black start in parallel is explored, which open up a new way for the application of grid technology in the black-start progress.