Ultra-supercritical Generator Transformer Unit Protection Technology Research

Coal-fired power is still the main force of China’s power industry, the ultra-supercritical units have obvious advantages in energy saving and environmental protection for their prominent characteristics of ultra-high parameters and ultra-low energy consumption. To ensure the safe and stable operation of the ultra supercritical units, the configuration of relay protection with good performance, reliable action and rational structure is very necessary. Therefore, the ultra-supercritical generator transformer unit protection technology research has important theoretical and practical significance. In order to improve the level of protection device selection, engineering design and operation maintenance for the ultra-supercritical generator transformer unit, this article takes the characteristics of ultra-supercritical generator transformer unit protection technology as the center, and conducts in-depth study about the key technology of ultra-supercritical generator transformer unit protection, the practical application, protection operation maintenance technology and typical accident analysis. The main contents include:(1) According to the characteristics of ultra-supercritical units, the key technical problems of generator transformer protection and their solutions are studied. TA saturation and its influence on the main protection of generator transformer unit are studied; zero power cutting protection scheme for large unit is proposed; the ultra-supercritical units generator stator and rotor grounding protection scheme is given.(2) Taking the CSC-300series generator transformer protection used by our plant as an example, this article sums up the technical features and successful operating experience of this generator transformer protection, and the experience is worth using for reference in the process of equipment selection, engineering design and operation maintenance.(3) Measures to improve the operation and management level of the ultra-supercritical generator transformer unit protection are given from perspectives of relay protection operation analysis, operation equipment anti-accident measures, technical innovation and technical management, etc.(4) Typical accidents and relay protection movements of the ultra-supercritical units are analyzed and systematically summarised from the secondary circuit, protection devices, setting and configuration, power supply systems, personal error and many aspects.