Identifying Fault in a Transient Harmonic Current Protection Scheme for HVDC Transmission Line

In this project, Based on the boundary characteristic of a dc line, the response of transient harmonic current in the line-commutated converter HVDC transmission system is analyzed under various fault conditions. The discrete Fourier transform is used to extract transient harmonic currents at both terminals of the dc transmission line and the type of fault can be identified by the transient harmonic currents. Transient harmonic current protection scheme is developed based on the distributed parameter line model in which the transient energy distribution over the line can be obtained from the current measurement at both terminals and the fault can be recognized from the calculated value simply. The two main factors that affect performance of the protection, fault resistance, and fault location are also considered. The increments of transient energy in the dc line are utilized to identify internal fault and external fault. With MATLAB, the test system is modeled considering the distributed parameters. It can identify the external fault correctly and quickly and provide correct responses under various fault conditions including high ground resistance faults.