Optimal design of q ‐axis field winding structure of dual‐excited synchronous condenser

Abstract

The dual-excited synchronous condenser (DESC) has two field windings whose axes are located at direct and quadrature axes respectively. The DESC has more capacity of absorbing reactive power than that of the traditional synchronous condenser (TSC). However, the q-axis field winding distributed on the d-axis magnetic pole surface can decrease the magnetic circuit area of the rotor core of DESC, thus it may result in the increase of the total harmonic distortion (THD) of the magnetic field and the oversaturation of the rotor magnetic circuit. In order to obtain better electromagnetic characteristics of DESC, a q-axis field winding structure is proposed by optimising the number of slots, slot pitch and slot dimensions. The influences of the number and pitch of slot in q-axis on the air-gap radial flux density and THD of DESC are studied under the d-, q- and dual-axis excitation modes. The dimensions of the q-axis slots are optimised by combining the time-stepping finite element method and Taguchi method, and the optimal structure of q-axis field winding is obtained. A 10-kVar DESC is developed to verify the simulation results. This study provides theoretical basis for the design and manufacture of the DESC.