Three-phase Adaptive Reclosure Of Parallel Transmission Lines With Shunt Reactors

With the increasing of network capacity,more and more lines adopt double-circuit lines on the same pole,in order to reduce outlet line corridor.Due to the long distance between two lines,line-across faults are easy to happen.In order to commit normal work of transmission line,the automatic reclosing technology has been widely used in electric power system.It is an effective method to improve the stability and synchronize of power systems.However,the present auto-reclosure very blindness,the disability to differentiate the permanent fault and the transient fault.In order to avoid the harm of reclosing blindly,the type of fault should be estimated before reclosing is implemented to realize self-adaptive reclosing.Therefore,the reclosure of double-circuit line has important practical significance.This paper focus on double-circuit lines on the same pole with shunt reactor.Firstly,analyzing the shunt reactors current characteristics of fault phase.Study show that:Under transient fault conditions,when faults disappeared,the fault phases shunt reactors current have low-frequency and power-frequency periodic components with beat frequency characteristic;Under permanent fault conditions,the fault phases shunt reactors current only have power-frequency periodic component,no low-frequency periodic components with no beat frequency characteristic.Based the principle of segregated current differential,a method to judge fault character for parallel transmission lines with shunt reactors is proposed.In the proposed method,the currents in shunt-reactors are taken as known quantities.This paper calculates capacitive current compensati-ng by phase-modulus transformation with six-sequence fault component,and uses current differential principle of shunt reactors currents after compensating are compared.For the parallel double-circuit transmission lines on the same tower with shunt reactors,in order to verify the proposed three-phase adaptive reclosing criterion validity and effectiveness.Taking transient faults as a reference model,using the ATP to simulate the different fault nature with different transition resistance and different fault location.Analyzing the data and waveforms obtained by simulation.Study show that:Under transient fault conditions,when faults disappeared,the fault phases quality of movement close to zero;Under permanent fault conditions,the fault phases quality of movement far more than zero.This criterion can correctly distinguish the nature of the failure to achieve three-phase adaptive auto-reclosure of parallel double-circuit transmission line on the same pole with shunt reactors.