| In urban distribution network,the cable has gradually replaced the the overhead line and become a major power supply lines because of its small footprint,high reliability for power supply,not susceptible to environmental impact and have other characteristics,As most of the cables are laid in the cable trench or buried in the ground,the fault is not easy to find,therefore,accurate the fault location has a very important significance.This paper presents a simple fault analysis method,to build accurate ranging equations and to achieve accurate ranging.This paper establishes the distribution parameter model,which takes into account the high order infinitesimal quantity.The model accurately calculates the distribution characteristics of the line parameters,and satisfies the requirements of the cable fault location in distribution network.On the basis of the model,the fault location equation is constructed according to the principle of equalizing the instantaneous value of zero-mode voltage from both ends of the line to the point of failure.The equation is the time domain differential equation for arbitrary voltage,line parameters and length of the line transient analysis.To solve the problem of high order derivative of zero mode signal,this paper proposed a method of sinusoidal approximation for the zero mode signals.This method overcomes the shortcomings of differential approximation instead of differential derivative error,and improves the accuracy of ranging.Aiming at the lack of local search ability for the particle swarm optimization algorithm,a fault location algorithm based on particle swarm-Newton iterative fusion is proposed to solve measuring the fault distance.This paper use the ATP and the MATLAB to simulate the single phase ground fault in different conditions,the measurement method proposed in this paper is verified by simulation.The simulation results show that the proposed method is effective and accurate in fault location. |
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