A review of power quality issues in electrified rails

Abstract

Electrified railways are among of the largest consumers of electric energy with longitudinally distributed power supply stations and connected to lines fixed (unmovable) electrical loads (consumers) and moving loads (vehicles), which operate, in general case, in nonlinear pulse modes. Due to the electrical non-linear nature of power stations and loads, current and voltage distortions appear in railway lines that devastating impact on the entire power system and consumers. The development of high-speed railways and the use of new types of rolling stock with power electrical equipment and pulse-width modulation of the traction current lead to problems with electromagnetic compatibility (EMC) and power quality in feeding grids that can adversely influence on train movement safety.The purpose of this article is to give a brief overview of power quality issues in electrified railways and also to consider related PQ standards. The main power quality disturbances are illustrated by using fragments of the traction current and voltage time-dependences measured during tests of the rolling stocks on electromagnetic compatibility with rail circuits.The traction current and voltage were registered in vehicle power equipment circuits, using a current and voltage probes whose signals were converted by analog-to-digital converter and recorded by PC.The different definitions of power quality presented in standards and literature are discussed.The main power quality disturbances were illustrated using specially chosen characteristic fragments of registered traction current, and some their parameters and electrical processes caused them are considered.