Power system is a nonlinear system with many disturbances

and the presence of the disturbances may cause the oscillation of the transmission capability.In order to effectively suppress low frequency oscillation

we studied the nonlinear calculation method of low frequency oscillation frequency and its application.Moreover

we proposed a new nonlinear approach to analyze the frequency of low frequency oscillation based on energy function and incomplete elliptic integral.Firstly

amulti-machine systems

which is equivalent to a SIMB system according to coherency

was established.Then

the Hamilton energy function of the corresponding simplified system was constructed by using the Lagrange function method.Finally

an exact expression of calculating the frequency of the low frequency oscillation in certain state was obtained by the derived form of the elliptic integral.Furthermore

the proposed method was compared with the traditional linearization method in the New England 10-machine 39-node system for low frequency oscillation simulation analysis and frequency calculation with MATLAB.Simulation results show that the maximum calculation error of the oscillation frequency is ≤0.04 Hz in the analysis of power system low frequency oscillation

and the calculation speed is faster.