A Planning Method for Partially Grid-Connected Bus Rapid Transit Systems Operating with In-Motion Charging Batteries

Andrés E Díez,Mauricio Restrepo

doi:10.3390/en14092550

Andrés E Díez, Mauricio Restrepo

Open Access

https://doi.org/10.3390/en14092550

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Journal: Energies	Publication Date: Apr 29, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: Pontifical Bolivarian University, Universidad del Norte

Abstract

This paper presents an electrical infrastructure planning method for transit systems that operate with partially grid-connected vehicles incorporating on-board batteries. First, the state-of-the-art of electric transit systems that combine grid-connected and battery-based operation is briefly described. Second, the benefits of combining a grid connection and battery supply in Bus Rapid Transit (BRT) systems are introduced. Finally, the planning method is explained and tested in a BRT route in Medellin, Colombia, using computational simulations in combination with real operational data from electric buses that are currently operating in this transit line. Unlike other methods and approaches for Battery Electric Bus (BEB) infrastructure planning, the proposed technique is system-focused, rather than solely limited to the vehicles. The objective of the technique, from the vehicle’s side, is to assist the planner in the correct sizing of batteries and power train capacity, whereas from the system side the goal is to locate and size the route sections to be electrified. These decision variables are calculated with the objective of minimizing the installed battery and achieve minimum Medium Voltage (MV) network requirements, while meeting all technical and reliability conditions. The method proved to be useful to find a minimum feasible cost solution for partially electrifying a BRT line with In-motion Charging (IMC) technology.

Highlights

Since the beginning of transit electrification in the last quarter of the 19th century, Grid-connected Systems (GCSs) became the core of mass transit in main cities of Europe and North America, starting with London metro, electrified by 1890 [1]
The overhead line cost varies from 200 kUSD/km to 600 kUSD/km, the traction substation cost ranges from 100 kUSD to 300 kUSD, the battery cost goes from 100 Unitary cost of feeding substation (USD)/kWh to 300 USD/kWh, the depot charger cost alternates between 500 USD/kW and 700 USD/kW, and the overhead charging power changes from 20 to 50 kW
These scenarios are intended to take into account the effect of variable costs that rely on local parameters, such as labor costs

Summary

Introduction

Since the beginning of transit electrification in the last quarter of the 19th century, Grid-connected Systems (GCSs) became the core of mass transit in main cities of Europe and North America, starting with London metro, electrified by 1890 [1]. By the decade of 1920s, electro-mobility prevailed in medium-capacity surface transit, in the form of intricate networks of trams, trolleybuses and cable cars, and even intercity routes experienced a golden age with commuter railways. All of these modes had one thing in common: their energy was continually supplied by the electric grid. Nowadays, when a new wave of electro-mobility motivated by recent advances in Lithium-ion (Li-ion) batteries, with the subsequent mass production and use of electric car, buses, bikes, motorcycles and a great variety of the so-called last-mile vehicles, grid connected systems and vehicles are still responsible for consuming about 85% of the electricity in the transport sector [2]. The energy consumption of the global BEB fleet in 2019, which corresponds to 11.46 TWh, was about the same of the total urban rail energy consumption in Europe [2,3]

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Conclusion