Research On State Estimation And Fault Location Technology Of Distribution Network Based On Sparse Micro-PMU

As a part of the digital power system,the Micro-Phasor Measurement Units(micro-PMU)are gradually used in the distribution network,making direct measurement of the voltage and current phasors of the distribution network possible.Research on micro-synchronous phasor measurement technology applicable to distribution network,and apply it to the field of dynamic monitoring and sensing of distribution network,which can provide more reliable data support for distribution network state estimation and fault location.Due to technical and economic constraints,only a small amount of micro-PMU can be placed in the distribution network.In order to fully exploit the role of microPMU in the distribution network,this paper proposes an optimized scheme of microPMU placement suitable for the current distribution network.Optimization placememnt methods,according to the number of different micro-PMU placements,are proposed to meet the needs of different scenarios.At the same time,considering the asymmetry of the network structure of the three-phase distribution network,the topology-based observability analysis rules applicable to the three-phase unbalanced distribution network are proposed.Applying a small amount of micro-PMU measurement directly to the existing state estimation model still cannot overcome the problem of state estimation nonconvergence caused by insufficient measurement.The nonlinear dynamical system method has been applied to the state estimation of the transmission power system.The method has the characteristics of global convergence and can effectively converge when the measurement is insufficient.In this paper,the method is applied to the distribution network state estimation,and considering the difference between the data of different measurement systems,the concept of local state estimation is proposed for the measurement provided by micro-PMU,and the measurement residual constraint is added.In the state estimation model,different dimensionally accurate state estimation solutions are provided for different applications.The multi-point real-time synchronous measurement provided by the micro-PMU in the distribution network can effectively improve the speed and accuracy of fault location.This paper further extends the fault location technology of transmission power system based on PMU measurement proposed by Chih-Wen Liu et al.,and performs fault location of distribution network under different conditions of line parameters.At the same time,based on the information provided by local state estimation,the number of micro-PMU placed can be reduced to increase the economics of the devices.