The Research On Dynamic Equivalent Principle For Non-analytic Complex Power System Voltage Stability Analysis

In the modern large power system, voltage collapse accidents causes extremely serious consequences, voltage stability problems become a threat to the large power system security, the international electrotechnical organization has listed voltage stability problem as international power industry’s hot and frontier problem.Power system is not only a nonlinear system, but also a complex-variable system, Complex-variable function theory fails to analysing dynamic characteristics of nonlinear power system. So far, there are not scholars who use complex analysis methods to studing non-analytic complex power system voltage stability. This paper adopted complex analysis method to analyzing complex-variable power system voltage stability problem, it is not only of theoretical method innovation, but also of important practical value.This paper put forward quasi-derivative definition and algorithms of the non-analytic complex function, accordingly deduced non-analytical complex power system maximum transmission power conditions, and get the Extended Thevenin dynamic equivalent principle of nonlinear power system voltage stability analysis. The principle is that if the non-analytical complex power system wants to get the maximum power, it must follow this principle:the modulus of load static equivalent impedance should be equal to the modulus of Extended Thevenin dynamic equivalent impedance; derived the Extended Thevenin equivalent parameter calculation formula, which theoretically solved the Thevenin equivalent parameter online identification difficulties;Based on the Extended Thevenin dynamic equivalent principle, by establishing the power system Extended Thevenin nonlinear mathematical model, put forward Extended Thevenin nonlinear equivalent principle of a wide range limit load power and voltage stability limit threshold voltage analytic calculation.Extended Thevenin dynamic equivalent principle is able to quickly and accurately predict power system limit load power and voltage stability limit threshold voltage, which can solve the trend of convergence and accuracy loss of of the saddle-node bifurcation point calculation.IEEE14node system and IEEE30node system simulation results verify the correctness of the proposed method. Extended Thevenin dynamic equivalent principle and Extended Thevenin nonlinear equivalent principle can provide a set of effective method to studying and analysing the power system static voltage stability. The proposed theory provided new step length selection method for the classic continuous flow calculation.In power system voltage stability analysis, system static transmission capacity calculation and continuation flow calculation, it will have extremely broad application prospect.