Research On Backup Protection For High Voltage Transformers

The application of large capacity transformer is used progressively with the scale of power system expanded, and the higher capability of transformer protection is desired. Composed to main protection of transformer,the theory of backup protection of transformer is mature and simple, but there are some problems in practice. The configuration of functions is determined by environmental factor, both hardware and software of the device are usually changed for the different needs. So the adaptability of equipment is limited, and the maturity of equipment is not ensured, either the security. Research on new type equipment of transformer protection is all along kept trace widely by relay protection researchers. Having analyzed the pivotal technology problem about research and development of backup protection for large capacity transformer, the paper presents the whole scheme for the general backup protection.At first, this paper introduces the evolvement and actuality of transformer protection, the current problems and trend is discussed. For solving the problem of massive principles and complicate configurations during actual application of transformer backup protection, having studied previous experience, an idea based on maximum configuration is raised for developing general backup protection system for transformer, making the equipment be applied to different voltage grades, such as 220kV,500kV,etc.principle of design and function configuration are presented in this paper, also approach to making protect function adjusted automatically.The platform of equipment is designed, also tested. The hardware of general equipment for transformer is basically made up of ARM and DSP, which possesses high-powered and expansibility. The connection between panel and motherboard is designed distinguishingly, so reliability and anti-jamming capability of equipment is improved. Configuration and modules of equipment are presented concretely.The principles of backup protection are important for the capability of device. Having analyzed the principles of backup protection in practice, including the distance protection, and low-voltage over-current protection, methods for solving the problems are presented respectively.The design of software is exigent because of complicated function of general protection, Key technology problem is analyzed deeply for software design. Basic configuration of software system is presented. The approach that makes the inputs and outputs of protection system adjusted freely is also presented.General backup protection equipment for transformer has been tested by static simulation experiment. The experiment results manifest that capability of equipment has come up to prospective destination, and it can fit in with the Needs of transformer protection. Methods and results of tests for the equipment are introduced in this paper.At last, the paper makes summarization for research, and expectations for farther work.