Analysis Of Sub-Synchronous Oscillation Caused By Grid-Integration Of Double-Fed Wind Turbines Via Series Compensation

With the rapid development of wind power technology and the reverse distribution of wind energy and load,the transmission of wind power resources needs to be transported over long distances.Adding a series compensation line can improve the utilization efficiency of the wind power.However,adding a series compensation line causes the system to generate sub-synchronous oscillation.In this paper,the sub-synchronous oscillations of the three-fed wind turbines through series-compensated grid-connected are studied,and the influencing factors affecting the interaction of sub-synchronous control are obtained.The corresponding suppression strategies are proposed according to the influencing factors.In order to study the sub-synchronous oscillation of the doubly-fed wind turbines through series-compensated grid-connected,the wind turbine model,the transmission shafting model,the pitch control system model and the doubly-fed induction are first established according to the sub-synchronous oscillation principle of the doubly-fed wind turbine.The generator model,the converter control model and the series compensation capacitor line model are used.Then the small-signal mathematical model is established according to the eigenvalue analysis method.The eigenvalue and the participation factor are obtained by solving the state matrix.The analysis of the participation factors is obtained.The influencing factors affecting SSCI include wind speed Vw,series complement,and inner and outer loop parameters of rotor side converter RSC.Finally,the relationship between the inner and outer loop parameters of the RSC of the rotor-side converter the string compensation Kc,the wind speed Vw and the damping ratio of the SSCI system is verified by the time domain simulation method,and the wind speed is reduced and the string complement is obtained.The increase and the increase in the SKp2 parameter of the converter can induce a risk of SSCI in the system.According to the influencing factors affecting SSCI,a hybrid modulation damping suppression strategy is proposed.firstly,the active damping control strategy and the reactive damping control strategy are theoretically analyzed.Secondly,the hybrid damping controller is optimized according to the hybrid edditional power damping control,and the parameters are set by the parameter tuning method.Finally,the reiability of the suppression strategy is verified by time domain simulation.