Influence of Rotor Structure on Electromagnetic Characteristics of Dual-Excited Synchronous Condenser under Different Operating Conditions

The Dual-Excited Synchronous Condenser (DESC) has greater reactive power regulation capability and inertial support capability compared to traditional one, which plays a crucial role in stabilizing voltage and frequency in the power system. The rotor winding distribution has a significant impact on the excitation magnetomotive force (MMF) and operating performance for electric machines, especially for the DESC with two sets of field windings. In this paper, the fundamental and harmonic components of excitation MMF for DESCs with concentric rotor and wound rotor structures are analyzed and compared based on quantitative calculations. The finite element models of DESCs with different rotor structures are established to study their electromagnetic characteristics. The magnetic flux density distribution and loss characteristics of three 30-Mvar DESCs with different rotor structures are analyzed at synchronous and asynchronous speeds. It is indicated that the DESC with wound rotor structure generates a high excitation magnetomotive force and exhibits moderate losses under different operating conditions. The results can provide basis for rotor design and the operating characteristics at synchronous and asynchronous speeds of the DESC.