Fault Location Method for Three-Terminal Lines in Distribution Network Based on Line Voltage Measured by μMPMU

Abstract

With increasing scale and integration of distributed generations, it has become progressively significant for operation of modern distribution network to locate fault in widely used three-terminal lines accurately. For the using V/V connection in the voltage transformers of distribution network, only two line voltages are measured in China. Without phase voltage and accurate line parameters, the existing fault location method based on impedance can’t be applied in distribution network any more. To solve this problem, a fault location method is proposed for three-terminal lines based on line voltage measured by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mu }$ </tex-math></inline-formula> MPMU (micro-multifunctional phasor measurement unit) without requirement for accurate impedance parameters. The transformation from two line voltages to positive-sequence component is proposed at first. Then location equations are established on the basis of positive-sequence network, with impedance parameters of lines and fault position as unknown variables solved together. The influence of random measurement noise is suppressed by applying the characteristics of fundamental frequency component’s amplitude and initial phase. The simulation results show that the proposed method has high accuracy and reliability, and can overcome the limitation of line voltage measurement, inaccurate impedance parameters, and measurement noise.