Research on parameters drift problem in tracking Thevenin equivalent

This paper derives analytical fraction expression formulas of Thevenin parameters and thoroughly discusses the parameters drift problem in tracking Thevenin equivalent. After the essential reason of the parameters drift problem is revealed, the rise and fall ranges of parameters drift are decided by the relation between the magnitude order of the true values of numerator and denominator of analytical fraction expression formulas and their error. The strategy that the rise and fall of parameters drift can be rejected and the optimization method of the samples waiting to be selected are proposed. It is useful to adopt the P-V relation checking and the operation pattern checking. The works in this paper can guarantee that the results of tracking Thevenin equivalent parameters are close to the reality.