Vertical shaft tubular pump stations are widely used in low-head, large-flow water conservancy projects due to their advantages of low head requirement, large flow capacity, and high efficiency. Based on an integrated electromechanical coupling transient modeling approach using User-Defined Functions (UDF), the dynamic response mechanism of this pump type during the accident shutdown transition process has been systematically analyzed. The results indicate that the inlet-outlet pressure difference (Δp) is a key parameter affecting the transient response. After power failure, the impeller angular velocity (ω) and unit flow rate (Q) synchronously decay and eventually converge to a reverse runaway steady state. High pressure difference conditions induce significant spatial inhomogeneity and pressure pulsations on the blade surfaces, significantly intensifying dynamic loads. Energy analysis further reveals that the inlet section and the impeller zone are the core areas for energy dissipation due to water hammer effects and flow separation, respectively. This study establishes a linear prediction model between the maximum runaway angular velocity ωmax and the pressure difference, providing a theoretical basis for the safety protection and transient control of similar pump devices.
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