Assessment of energy management opportunities in a DC traction network: Case study: Passenger rail agency of South Africa, Western Cape

This paper presents an assessment of energy management and energy efficiency through regenerative braking, reversible substations, load shifting and time shifting methods. The paper also compares the Eskom different tariffs with the Municipality tariffs. This may involve the switching off of expensive substations during peak hours and only use adjacent substations with cheaper tariffs. Timetable changes were also considered to assist in minimizing energy cost. Amongst PRASA fleet there are 10M3 and 8M classes that are capable of sending power back to the line through regenerative braking. Another option is to eliminate demand kVA charge by increasing the notified maximum demand (NMD). Based on this research and measurements, an energy cost of at least ZAR 10 Million per year can be saved without any additional cost to the normal operation.