## 1 Introduction  
The pumped storage power station plays a few important roles in the power system, such as peak load regulating, emergency standby and directional service. The pump-turbine, as a reversible unit, needs to take two different working conditions into account: the pump model and the turbine model. There are many overflow components, and transition conditions are frequent, so its internal flow is complex with strong pressure fluctuations. It is very important to reduce the influence of pressure fluctuations, which can induce the unit to produce vibrations of a specific frequency and lead to the resonance of components, or even vibration of the plant due to improper design. A runner with splitter blades has gradually been recognized to play an important role in reducing pressure fluctuations and improving cavitation performance. At present, foreign and domestic scholars, using computational fluid dynamics and the fluid-structure interaction numerical calculation method for analysis of the internal flow of the pump-turbine, have sufficient cognition about its mechanism and also give relevant improvement measures [1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14]. [PERSON] [15] adopted a non-invasive measurement method to monitor and track the rotation stall of the pump-turbine and identified the frequency characteristics, and characteristics of the rotor-stator interaction under the rotation stall, which are expected to be applied to state monitoring in the actual operation of the full-size pump-turbine. [PERSON] [16] focused on the impact on aerodynamic performance and aeroacoustics caused by the presence of a pylon and concluded that the use of active flow control, in the form of pylon trailing edge blowing, can alleviate these adverse installation effects to a notable extent. [PERSON] [17] performed an aeroacoustic analysis with the Frowcs Williams-Hawkings tool APSIM+ for both configurations and came to similar conclusions. [PERSON] and [PERSON] [18] presented analysis and validation of the Deutsches Zentrum fur Luft- und Raumfahrt (DLR) numerical approach to coupled CFD -CAAsimulations to enable reliable predictions of the aerodynamic and aeroacoustic performance of Contract Research Organization Reagent (CROR) propulsion systems. [PERSON] [19] demonstrated that the pressure field generated in the compressor consists of spinning mode patterns, and that the number of lobes in each pattern, together with the frequency of the pressure fluctuations, gives the speed at which the pattern spins. Additionally, there is a critical pattern speed which separates the subsequent behavior of the pattern into one of two different categories. [PERSON] [20] studied the phase resonance phenomenon in centrifugal rotating machinery, compared and analyzed the phase resonance of the working condition of the pump and turbine, respectively, and revealed the important influence of the direction of rotor-stator interaction and radial velocity fluctuation on the phase resonance. [PERSON] [21] studied the performance and internal flow of a small centrifugal pump with a large blade outlet angle through experiments and numerical simulation by using a shunt blade. Through experiments and numerical analysis, [PERSON] [22] compared the cavitation performance of centrifugal pumps with and without diverging blades and found that the cavitation allowance of the impeller with splitter blades decreased significantly at high flow rates, while the cavitation allowance increased significantly at low flow rates. [PERSON] [23] introduced a kind of turbine runner with a long and short blade applied to the adjustable speed setting. By improving the operation efficiency of partial loads, the stable operation range under the speed regulation mode was expanded. In this paper, the frequency of interference is predicted theoretically, and several monitoring points are set up in different components and locations of the pump-turbine.