Non‐unit protection scheme for HVDC transmission lines based on energy of voltage difference

Abstract

This paper presents a non‐unit protection scheme for LCC‐HVDC transmission lines based on the energy of voltage difference. The change in the line average voltage is used to detect the fault, whilst faulted pole selection criterion is calculated by using the ratio of the average voltage change at positive and negative poles. The protection criterion calculated as the energy of second‐order difference of the DC line voltage determines whether the fault is internal or external. Numerous simulation and field data test are performed to validate effectiveness of the proposed scheme under a vast variety of fault conditions. The tests include different types of internal and external faults, sensitivity to transferred power variation, sampling frequency, length of data window, change of smoothing reactor, effect of lightning interference, change of the line length, change of the operation mode, and effect of noise. The scheme is a single‐end protection method and does not require sophisticated computations.