Large-signal Stability Analysis Using Takagi-Sugeno Fuzzy Model Theory for Fractional Frequency Transmission System

The rapid development of renewable energy requires transmission technology innovation. The fractional frequency transmission system (FFTS) is a promising solution for largescale renewable energy transmission. While the stability analysis becomes urgent affairs for engineering application. Especially for the large-signal disturbance, previous methods on small-signal stability would be inapplicable. Thus, the system-level large-signal stability analysis method of FFTS is proposed considering the system parameters, control strategy of AC/AC converter and PLL in this paper. The state-space Takagi-Sugeno fuzzy model is proposed for Lyapunov function construction. Then the corresponding large-signal stability domain of attraction (LSDOA) could be obtained. In order to overcome the qualitative and approximate problem of traditional stability analysis method, the stability strength and affine angle is introduced initially. Ultimately, considering the influence of system parameters with different-frequency interaction feature, the large-signal stability results of FFTS under different gird faults could be revealed completely. The effectiveness of proposed approach is verified by case and simulation.