Analytical Calculation of Electromagnetic Force of VSPS Considering Harmonic supply in Rotor Converters

Variable speed pumped storage (VSPS) generator-motor has multiple operating conditions and complex air gap flux density under harmonic supply in rotor converters, and vibration performance is also an important indicator at design stage. This study firstly deduces the analytical solution of air gap flux density and radial electromagnetic force density of VSPS generator-motor, considering stator slotting, rotor slotting, and harmonic components in rotor converters. With this method, the potential low order electromagnetic force with the larger amplitude can be predicted accurately and the influence of harmonic supply in rotor converter can be analyzed thoroughly. With a 336MW VSPS generator-motor, finite element analysis (FEA) is performed and the spectrum of electromagnetic force is got by 2D-FFT. The reliability of the analytical model is verified.