Longitudinal Differential Protection. Line

Current differential protection is an important developing direction of HV line main protection. This paper simply describes the basic tenets of current differential protection. Basic the principles of the tenets, this paper dose in-depth research about basic differential, fault component differential, zero-squence differential protection and current compensation. By analysis, it can be find that comparing with basic differential, the fault component will not be affected by load current and have higher sensitivity. Zero-squence differential can not be affected by transition resistance, it can rapid cut the fault. This paper puts forward a new fault phase selector of zero-squence differential protection. At the last chapter of this paper, this paper presents two current compensation methods of differential protection. The compensation method of current compensation can reduce the imbanlance current of external fault and unloaded switching, thereby reduce the action threshold, enhance the sensitivity and action speed of the protection greatly. Simulateing about fault phase selector of zero-squence differential protection and current compensation with ATPDRAW and MATLAB software also have in this paper.