Simulation research for the different fault of power line exerting an influence on the distance protection

Aim at the different short circuit fault happening between the phases of power line,analyzes the faults exerting an influence on the distance protection of power line,according to the basic principles of the distance protection of power line,calculates the value of every phase voltage in the three-phase system,uses PSCAD/EMTDC establishing the simulation model of double-ended power supply system and makes simulation experiment.By the measuring voltage,current and impedance,judges the distance of fault point and act characteristic of the protection.The results shows that the corresponding measured impedance can reflect the distance of fault point of protection correctly when the different short circuit fault happened between the phases in the three-phase power line of double-ended power system,the impedance relay can act accurately and quickly,ensures the sensitivity of system response and improves the reliability of protection.