Influence of Transformer Configuration on Relay Protection in Overseas Electric Power Engineering

The parameters and configuration scheme of current transformers are key factors related to the correct operation of relay protection. The configuration of transformers in overseas power engineering has different requirements from the standards of the Chinese power industry. This paper studied the characteristics of power grids, main electrical connection scheme and requirement for setting protection devices in Africa, which are important prerequisites for conducting reliability verification studies current transformers. By analyzing the differences in key issues of concern through case studies, propose reasonable equipment configuration optimization methods, including: improve the calculation coefficient of PX class current transformers to have wider applicability, adopting multi-tap or auxiliary converters to adapt to significant short circuit current differences in the near/long term of the system, balancing the dynamic/thermal stability of protective devices and setting current requirements, solving the special application problem of connecting small capacity equipment to large capacity systems. The above measures have been verified through engineering, reducing the impact of inappropriate current transformer configuration.