Research On Automatic Adjustment In Power Flow Analysis For Large-scale Electrical Power Systems

The inclusion of automatic adjustment in power flow calculation, aimed at meeting the demand of special operation and control instead of by manual work, can have a major effect on computation efficiency. This dissertation is mainly discussing the problem of power flow automatic adjustment in large-scale power systems.Firstly, power flow models are studied, including AC system power flow algorithms, a sequential method for the calculation of AC/DC combined systems, and a decomposition method for the analysis with FACTS devices. How to calculate the power flow of an AC/DC combined network with FACTS devices is also discussed.Secondly, automatic adjustment methods in power flow calculation for large-scale power systems are researched. By means of sensitivity analysis, a new method for parameter adjustment is proposed, which can be used to solve the common computing problem of adjusted solutions. The problem of single objective adjustment with multi controls is solved. How to calculate sensitivity is discussed, and several kinds of sensitivity equations are conducted. A lot of calculations have verified the validation of this method.In the field of multi-objective adjustment, a new parallel method based on sensitivity is also brought out. It mainly contains two parts. Firstly, when the number of the controls is smaller than that of the objectives, a Lagrange method is adopted so that the change of adjusted parameters is minimized. Secondly, when the number of the first is larger than latter, the least square method is introduced so that objectives as many as possible are satisfied in maximum. This method takes the influence of each control to all objectives into consideration and can generate a good result. Optimization principles of the selection of objective and control are also given.Finally, according to the analysis of software currently in use, the demand and functions of a new power flow program are put out. Its architecture is based on server/client pattern. By use of object-oriented design method, the hierarchy structure of network elements is built. Techniques of how to construct and calculate with sparse matrix are detailed. Key items of automatic adjustment are discussed. This software has been developed and exhibited good characteristics in application.