The Schemes Study Of Substation 10kV Busbar Protection

In current Chinese substations, the busbars of 35kV and below are normally not equipped with special busbar protections. The most popular busbar protection schemes for middle-low voltage busbars are the backup over-current protections of adjacent elements. Since the harm of arc short-circuit faults of busbars is proportional to the lasting time of the faults, some distribution equipments of the feeder are possibly damaged before the busbar protections are tripped, because the protection time of backup over-current protections of the adjacent elements is often longer than one second.In August 2005, a short circuit fault occurred in a 10kV busbar of the 220kV Yuanjiang Substation of Dongguan Power Suply Bureau. The complex voltage over current protection in the 10kV side of the transformer refused to trip since the 10kV complex voltage was not satisfied with the trip setting. This resulted in a serious damage to the 10kV switch cabinet. The principal reason of such a developed fault in the middle-low voltage side is the lack of special busbar protection.This paper firstly studies various protection principles and schemes of the 10kV busbar protection in China and other countries. The advantages and shortcomings of theses schemes are discussed in state of arts, characteristic actions, installation conditions and costs. Based on the research of the principle of feeder over-current lock mode 10kV busbar protection, the implementation scheme is designed, and the setting principle is investigated. Secondly, the adaptability and action characteristics of feeder over-current lock mode busbar protection under different operation modes are analyzed with the consideration of the characteristics of 10kV busbar.Thirdly, according to the standards of the dynamic model experiments of 10kV busbar protection and the characteristics of Dongguan Power Grid, the simulation software and digital dynamic model system, which are applicable to Dongguan Power Grid, are developed based on the Hypersim real time simulation system. The dynamic model experiments are applied to the Shenzhen NARI equipments of feeder over-current lock mode busbar protection. The results of the experiments are also discussed in details. Finally, an economical and manageable special protection scheme is designed, which is to satisfied with the characteristics of busbar protection and can be applied in both constructing and constructed substations.