Evaluation of Parameter-free Fault Location Algorithm for Distribution Network Three-terminal Transmission Lines

Three-terminal transmission line is an important approach for the integration of distributed generation and the power supply of small loads in the distribution network. However, inaccurate or unknown line parameters can cause great errors in the results of most existing phasor-based fault location algorithms for this kind of line. Recently, one paper proposes a fault location algorithm without line parameter values, utilizing the post-fault measurements of three terminals. For the hypothetical fault on each section, because voltages at fault point respectively derived by three-terminal measurements should be equal, corresponding fault location equations involving the fault distance and line parameters as unknowns can be established. In addition, the redundancy of equations is enhanced using multiple groups of sampling data to reduce the influence of measurement error on the location result. Then, each equation set can be solved by the trust-region algorithm respectively. Finally, the fault point is located because the solution of equations is correct on condition that the actual fault point is on the assumed faulty section. In this paper, the above algorithm is evaluated under various fault position, fault resistances, fault types and usual measurement error, using Simulink and power system dynamic lab respectively.