Fast Weak Damping Eigenmode Calculation of Varying Operating Conditions
With the increasing penetration of renewable en-ergy resources and flexible loads,the damping characteristics of critical electromechanical eigenmodes change with the time in-variant operating conditions of power systems.When it comes to the dynamic stability evaluation,the QR method is accurate,but fails to satisfy the needs for online tracing.In order to cal-culate the time-varying eigenmodes,this paper proposes a method to reduce the state matrix order of the system via iner-tia equivalence.All state variables of an eigenmode are mapped to a new sub-space upon the modal clusters.However,the pat-tem matching and modal varying of eigenvalues in the calcula-tion may lead to discontinuous results.To solve the problems,the relevant factor index of the dominant clusters is proposed and a framework is built to achieve fast calculation of critical eigenvalues in different conditions.The critical eigenmode cal-culation method is tested in the IEEE 145-bus system,and the simulation results demonstrate its accuracy and rapidity.