Study of the transient current differential protection based on correlation analysis

In this paper, the principle of the current correlation differential protection based on the correlation integration is analyzed first. The advantages of the correlation differential criterion are proved and the disadvantages are also pointed out. Aiming to the disadvantages of the correlation criterion, an improved scheme was proposed in the paper. The power system models of different structures using ATP program are built to simulate these criterion completely. Simulation studies show that the improved scheme not only preserves the advantages of correlation criterion, but also increases many new virtues such as better sensitivity and reliability, simple to understand, easy to give out setting values. Studies also show that the improved scheme is more reliable and very suitable for the protection of EHV/UHV transmission lines.