Improved algorithm of wide-area current differential protection based on non-uniform quantisation

Current differential protection characterised by whole-line quick action has now become the main concept in the research of the wide-area relay protection algorithm. However, strict requirements on broadband and real-time capability are difficult to meet in actual projects. Aiming at reducing the system traffic while not compromising the protection performance, the study proposes an improved algorithm of wide-area current differential protection based on non-uniform quantisation. The algorithm is proposed based on the information theory and in view of the non-uniform distribution of information redundancy of current signal in different width intervals. Comparing with traditional current differential protections, the improved algorithm is able to retain the sensitivity and reliability of the protection while reducing at least 44% of the system traffic whenever internal or external faults occur. It facilitates the realisation of wide-area differential protection in practice. Through digital simulation and dynamic simulation, the study demonstrates that the algorithm can distinguish fault places correctly and features a relatively high degree of sensitivity.