Multi-scale oscillation of pumped storage - wind power coupling system with surge tanks

Abstract Under grid-connected operation, pumped storage - wind power coupling system (PSWPCS) with surge tanks generates the problem of multi-scale oscillation, which leads to the complexity of dynamic response and difficulty of regulation control. Thus, this paper researches the multi-scale oscillation of PSWPCS with surge tanks. Firstly, the mathematical equations of PSWPCS with surge tanks are established. Then, the multi-scale oscillation and effect rules of surge tank area are investigated. Finally, the influence mechanism of multi-scale oscillation is studied. The results indicate that PSWPCS with surge tanks has multi-scale oscillation. The ultra-low frequency damping performance of upstream and downstream surge tanks is stronger than that of single surge tank, and the negative damping characteristics of which changes significantly with the 50% increase of upstream surge tank area. A larger water head of power station and smaller head loss of headrace tunnel are easier to induce the ultra-low frequency oscillation. The pitch angle controller of wind turbine can significantly suppress the low frequency oscillation under larger proportional and smaller integral gain. When proportional and integral gain of phase-locked loop controller are small, the sub-synchronous oscillation will be excited. Smaller stator self-inductance and rotor resistance can improve the system regulation performance.