Resonance characteristics of rotor speed and its suppression strategy for Type-I full-power variable-speed pumped-storage units

Type-I full-power variable-speed pumped-storage units (units under power priority control) are expected to become key equipment for grid frequency support due to their rapid power regulation capability. However, the water hammer effect acts directly on the unit rotor, thereby weakening the damping characteristics of the speed control loop in a certain frequency range. This paper reveals the resulting rotor speed resonance phenomenon, which manifests as a pronounced amplification of rotor speed gain under external disturbances within the corresponding frequency range, thereby posing a potential risk to the safe operation of the unit and constraining governor parameter tuning. The quantitative relationship between the resonance peak and the system's damping characteristics is further established. On this basis, a resonance suppression strategy is proposed by introducing a first-order lead compensator in series on the governor side. The trade-offs among resonance peak magnitude, response speed, and damping characteristics after compensation are then investigated. Furthermore, parameter design guidelines for the governor and compensator under different operating conditions are established based on multi-parameter optimization, enabling flexible adaptation to diverse performance requirements. Finally, simulation results show that the optimized parameter schemes achieve superior overall performance compared with the uncompensated case, thereby verifying the effectiveness of the proposed method.