Calculation of Synchronous Reactance and Analysis of Influencing Factors for Large Tubular Hydro‐Generator Based on Static Magnetic Field Model

The steady‐state synchronous reactance ( x d and x q ) of a hydro‐generator are key electrical parameters that characterise its operational characteristics. These parameters determine the voltage regulation and static stability of the generator, whilst also governing its grid‐connected active and reactive power control. Given the inherently narrow air gaps in tubular hydro‐generators, the influence of geometric structure and material properties on synchronous reactance and operational performance is particularly pronounced. Changes in structure or material alter the magnetic reluctance, which modifies the inductance and thereby determines the reactance value. Therefore, accurate and efficient calculation of synchronous reactance during the design phase is of paramount importance. This paper takes a 36 MW large tubular hydro‐generator as an example. Analysis of the static magnetic field model reveals the influence of stator skewed slots, damping bars and stator‐rotor core laminations on the synchronous reactance. The computational accuracy of the proposed method is validated against measured data, with high computational efficiency also achieved. This study provides direct and meaningful technical support for improving the accuracy and efficiency of reactance analysis in hydro‐generator and for enhancing their operational reliability. It also provides a theoretical basis for the precise simulation calculations of large tubular hydro‐generator.