Power Regulation Capability and Limiting Factors of AC-Excited Generator-Motor

AC-Excited Generator-Motors (ACEGMs) have wide regulation range and high steady-state stability, thereby it is widely used in the variable speed pumped storage power station. However, the power regulation capability of the ACEGM can be restricted by the heat transfer and the rotor converter voltage. In this paper, the power regulation range of the ACEGM is derived under the constraints of the stator and rotor temperatures and the rotor converter voltage. In order to obtain the power regulation capability of the ACEGM, the stator and rotor losses and temperatures are calculated by the electromagnetic-thermal coupling model. The variation laws of the stator and rotor highest temperatures along with the increase of the active and reactive powers are revealed. The power regulation range of the ACEGM affected by the stator and rotor maximum permissible temperatures are obtained. Moreover, the influence of the rotor converter voltage on the power regulation range is studied. It is obtained that the power regulation range can be reduced along with the increase of the slip. This study establishes a theoretical foundation for enhancing the power regulation capability of the ACEGM.