A New Line Differential Protection Principle Based on Correlation of Full Wave Current Data

Abstract

Grey correlation analysis can analyze and judge relationship between curves. The relationship between the full wave current data at both ends of a line before and after a failure is quite different. Accordingly, the fault correlation and non-fault correlation is defined. A new differential protection principle based on correlation of full wave current data is proposed. Then, action criteria is analyzed about the details of principle, natural anti-CT-saturation capacity, data window selection, the influence of two side current data asynchrony and so on. Furthermore, a protection principle based on the correlation of full wave fault component current is constructed, and the two algorithms are compared and their differences are analyzed. Finally, a 220kV double-ended network model is constructed with PSCAD and Matlab. Results show that the new differential protection principle can identify internal & external faults quickly and accurately based on the fault data within 5~10 ms. Benefited from the characteristics of the fault component current, the protection principle based on the correlation of full wave fault component current is more sensitive. Feasibility and effectiveness of the protection algorithm are verified.