Static Equivalence Research Of Power System

It is always restricted by the capability of computers and consumes much calculation time in various analyses of interconnected network which operates in different states. And it often turns to static equivalent methods to reduce the scale of interconnected system to solve this problem. The static equivalent methods are widely used in off-line or on-line analyses of power system. The basic problems of static equivalence are generally discussed in this paper. The selection of basic nodes and basic buses is the first step in reducing a interconnected network by using equivalent methods. This problem is deeply discussed based on a sensitivity analysis method in this paper. The non-linear errors are inevitable which are resulted by the characteristic of static equivalence. The mechanics of the production of non-linear errors is deeply discussed based on the analysis of normal Ward equivalence. And this becomes the theoretical base to improve the normal Ward equivalence. In practical application, the extended Ward equivalence can obtain satisfying precision in many cases. The particular deducing and improving course is described in this paper. And considering the actual requirement, it is programmed to solve the practical reducing problems and the emulating calculation is carried out with IEEE-57 system. The results of emulating calculation are used to proceed more analyses of the problems of Ward equivalence.