Analysis of induced components in hybrid HVAC/HVDC transmission lines on the same tower for various fault conditions

The use of Hybrid Parallel HVAC/HVDC Overhead Transmission Lines (HPOTL) on the same tower can improve the power transfer capacity and transmission line stability and reduce power transient swing, but it will also present some challenges. The most important one is the electromagnetic coupling between the HVAC and HVDC lines due to the proximity of the lines. The electromagnetic coupling phenomenon induces different voltage and current components in the lines for different conditions, including the fundamental frequency component in the DC line and the zero sequence component in the AC line. The magnitude of the induced components is much higher in fault conditions than in normal conditions. The electromagnetic coupling between the HVDC and HVAC lines has a significant influence on their equipment and protection systems. In this paper, the induced compo-nents in the normal and various fault conditions in HPOTL are investigated with the detailed modeling of the HPOTL. In addition, the effect of faulty phase(s) or pole(s) for AC, DC, and AC/DC intersystem faults, fault location, and fault resistance on the induced component in transmission lines are investigated. Simulation results show that the electromagnetic coupling can cause the mal-operation of the protection system in healthy lines.