Switching System's MLE Based Transient Stability Assessment of AC/DC Hybrid System Considering Continuous Commutation Failure

The commutation failure of Line Commutated Converter-High Voltage Direct Current (LCC-HVDC) cannot be avoided. This paper presents a novel transient stability assessment approach for AC/DC hybrid system considering continuous commutation failure. First, the conception and mathematical background of Maximum Lyapunov Exponent (MLE) of switching system is introduced, and the switching compensation matrix is derived. Next, the switching system model of AC/DC hybrid system considering continuous commutation failure caused by AC faults is established. On the basis of switching compensation, the MLE of switching system is calculated accurately, and the MLE based criteria are proposed to assess the transient stability of the switching system. Finally, the modified 39-bus system with LCC-HVDC added and the real power system are used as test systems to investigate the validity and effectiveness of the proposed transient stability assessment approach.