Research On Fault Location Method Of Distribution Network With Distributed Generation

Fault location for distribution network is one of the main functions of power distribution automation system.In order to ensure the power quality of users,reduce the time of a power outage due to fault,and improve the reliability of power supply,it is required that the distribution network can locate the fault section quickly and accurately after the fault.However,with a large number of Distribution Generations have been access,distribution network becomes an active network with normal operating power and fault currents flowing in two directions,which makes the fault location complicated and traditional location algorithms are no longer applicable.To look for a new fault location method suitable for the active power distribution network,the key technologies of fault location analysis,such as the impedance characteristic analysis of the monitoring point,the fault direction determination method and the fault location algorithm are studied in this paper.DG access may change the measurement impedance characteristics of the monitoring points and thus affect the applicability of traditional fault location methods.Taking Inverter Interfaced DG as an example,analysis for the impact of DG access to distribution network,Inverter Interfaced DG simulation model is established with Matlab/Simulink,the simulation results show that when different types of short circuit fault was occurs in distribution network with DG,the measurement impedance characteristics of some monitoring points may be inductive or capacitive.The accuracy of fault location results in distribution network with DG depends on the correctness of fault direction judgment.Fault direction judgment method based on fault component of the power frequency sensitivity is high,but only be suitable for the inductive impedance characteristics.In view of the DG's influence on the impedance characteristics in the distribution network,this paper proposes a effective method for fault direction judgment which is suitable for perceptual and capacitive impedance characteristics.Firstly,the distribution of each sequence fault voltage components and the action characteristics of the directional components are analyzed.Secondly,according to different types of short circuit faults,different direction criterion is constructed by comparing the magnitude of each sequence fault components voltage and the amplitude of each order fault component of the measured point voltage.Finally,establishing a distribution network model with DG verifies the validity of the directional criteria.The simulation results show that the fault directioncan be accurately judged and the sensitivity is high when the impedance characteristics are sensitive or capacitive.A new algorithm based on improved bat algorithm is proposed for fault location.The fault location optimization model of active distribution network is established,and the improved bat algorithm is used to solve the problem.For the defects of the basic bat algorithm,the Metropolis criterion of simulated annealing algorithm was introduced to set the acceptance criteria for the new bat individual and the original individual's fitness increment.If the new fitness value after perturbation is better than its initial optimal solution,the new solution is accepted.Otherwise,the new solution will be accepted according to the Metropolis criterion.The simulation results of the distribution network with multiple DG show that the proposed algorithm can locate the fault section of distribution network quickly and accurately,and it has a strong fault tolerance to the fault information distortion.