Midland line catenary distance protection review and implementation

The Public Transport Authority (PTA) of Western Australia aims to provide a safe and reliable transport service to Western Australians. The PTA is accountable to ensure that uninterrupted, reliable and safe power is supplied and distributed through overhead line equipment (OLE) to the train railcars. Rail cars on the network operate with 25kV AC supply. There are protection systems in place to protect the electrical network and isolate faulty sections from the rest of the network and prevent any further damage to equipment. The traction power network supplies the required power for the rail cars through the catenary and contact wire in the electrical network. The return current from the rail cars flows back through the rail tracks and return conductor (RC) wire to the feeder station using booster transformer (BT). Over the years PTA has decided to remove the BTs from the network due to strategic and financial reasons. This project is focused on the Midland line, as this is the only line where all the BTs are disconnected from the system. As result, the overall impedance of the traction power network was changed. This change caused the relay’s accuracy in the network, which results in operational delays. In other words, the distance to fault readings by the relays were no longer correct and, eventually, this affects the train operations and could cause delays in fault findings in the OLE network. Therefore, PTA has decided to update the distance protection relay settings. However, the first step performed under this project was to provide a test plan and measure the overhead line impedances and verify the measured data by theoretically calculate and modelling traction power system (in OpenPowerNet). All of the mentioned works were performed under this project except the traction power system modelling which were performed in collaboration with a PTA electrical engineer and all the input data in system modelling were provided under this project