Analysis and development of power quality metrics for railway electric networks

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2022
Thesis identifier
  • T16373
Person Identifier (Local)
  • 201894728
Qualification Level
Qualification Name
Department, School or Faculty
  • Ensuring acceptable levels of power quality (PQ) in electrified railway networks has become crucial due to the increased utilisation of power electronics within locomotives and power grids. There is a lack of clear analysis and standardised procedures focusing on PQ measurement techniques explicitly for railway applications, and therefore a need to develop appropriate PQ measurement methods and indices. This thesis addresses this gap through review and analysis of PQ phenomena and measurement methods applicable to AC railway signals. Recommendations of methods for rail PQ instruments are provided, including newly developed techniques to detect unique disturbances in AC and DC railway networks. A new measurement technique to identify voltage interruptions at locomotive terminals resulting from network re-configuration has been developed. It allows distinguishing these disturbances from voltage interruptions caused by faults in the system or failure of equipment, thereby improving event identification and classification. A half-cycle measurement interval, in contrast to the one-cycle approach proposed by the IEC 61000-4-30 standard for voltage dips and swells evaluation in grid applications, has been analysed and developed for improved detection and classification of short-time voltage events, allowing an enhanced correlation of their impact on rail assets, and supporting network planning and new standards for rail PQ instruments. It is shown that a new aggregation time interval equal to 50 cycles for 50 Hz signals is required to improve the accuracy of voltage and current harmonics measurements by rail PQ instruments. Due to improved tracking of the time-varying frequency components, a better estimation of harmonic emission levels in 25 kV 50 Hz rail systems has been proven, leading to improved health condition monitoring of the network assets. A novel and cost-effective method for detecting electric arcing phenomenon between Chapter 0. Abstract the pantograph and overhead contact line (OCL) of 3 kV DC railway networks has been developed. Information extracted about the geographical localisation of the arc enables predictive maintenance of the entire pantograph-catenary system, thereby reducing operational costs and improving the safety and reliability of DC rail networks. In summary, this work has addressed the need for focused analysis of unique railway PQ phenomena, has developed and proven the effectiveness of new tools for rail PQ monitoring, and has established a new foundation for health and condition monitoring in rail electrical systems.
Advisor / supervisor
  • Blair, Steven
Resource Type