STUDY ON SUBSYNCHRONOUS RESONANCE PROBLEM IN SERIES-COMPENSATED TRANSMISSION SYSTEM

Chengbing He, Dongchao Chen

School of energy, power and mechanical engineering, North China Electric Power University, Beijing 102206, China

The series capacitor compensation technique can improve the transmission capability of transmission system; however, it may cause subsynchronous resonance (SSR) which will seriously influence the safe operation of large turbo-generator shafts. Aiming at a series capacitor compensation transmission system, the transient torques of SSR is simulated in different compensation degrees and unit load levels. Based on the modified segmentation Prony algorithm (MSPA) proposed in this paper, the characteristic frequencies and damping parameters are identified and analysed. The MSPA, complex Morlet wavelet and time-frequency contour map are integrated and used in analysis of transient torques of SSR in time-frequency field. The results of study show that the transient torques develop towards divergence direction and the frequencies of SSR (converted to the rotor side) in negative damping area move towards into low frequency area with the increasing of the compensation degree. With the increasing of the power output, the torque values of each shaft section will increase, but the dominant oscillation mode will not change. The increasing of power output can make the damping effect slightly change and the trend of the change develops towards the direction that is not conducive to restrain SSR.