Quantification Analysis On The Energy Factors Of The Urban Rail Transit System

Characterized by high volume traffic, high rapid, high delay quality, using less land and lower pollution, urban rail transit plays a critical role in the public transportation system. With the rapidly growing economy and social developments in China, urban rail transportation has expanded drastically and the demands on energy consumption escalate accordingly. The huge cost makes efficient energy utilization in urban railway transportation an urgent and desirable issue. It is also benefit to the sustainable development of the urban rail transit system.This paper mainly focuses on the impacts of train characteristics and track profile design on the energy consumption of the urban rail transit system, and then further analysis the structure importance of the whole system energy consumption. The main contents include:(1) By summarizing the exit research results and analyzing the statistical data, the energy consumption of urban rail transit system contains two parts:train movement energy consumtion and station operating energy onsumption, the former of which is about 50%. The infrastructure and transport organization mode play a significant role on the train movement enegy consumption, which is the key point of this paper.(2) The paper proposes the estimation methods of train movement energy consumption and station facility energy consumption. As for train movement energy consumption, a model based on the meritorious electric current curve is developed. Additional, another method by transforming the power to the energy is proposed as well to estimate the energy consumption of train movement when the meritorious electric current curve is unavailable.(3) Quantity analysis the impacts of train characteristics and track profile scheme on train movement energy consumption, according to analytical analysis and simulation case studies. The results are concluded as follows:the impact of train characteristics on its energy consumption is related to the train target speed, while the difference of energy consumption among different trains is up to 19% even with the same target speed; Energy-optimized track profiles is always designed at the advantage sections which saves 6.7% energy consumption of train movement. Curve radius of the track profile also effects the energy consumption greatly, the smaller the curve radius is, the much more the energy will be consumed, furthermore. The increment of the energy consumption is positive correlated to the train target speed, which might up to 30%. The impact of curve radius on the train movement energy consumption can be neglected when the curve radius is larger than 800 meters. With the same stop scheme, train movement energy consumption per kilometers is decreased with the increment of inter-station distance, and the energy consumption is reduced by 13% for every 200 meters increment of the inter-station distance, from 400 meters to 2600 meters. The impact of inter-station distance on the train movement energy consumption can be neglected when the inter-station distance is larger than 2600 meters.(4) Quantity analysis the impacts of transportation operation mode on train movement energy consumption, according to analytical analysis and simulation case studies. The results are concluded as follows:the absolute train energy consumption is slightly increased with the passenger load-ratio. The energy consumption per passenger, however, is drastically decreased with the increment of passenger load-ratio. It is more sensitive when the technical speed is higher and the passenger load-ratio is relative lower. This decrease of energy consumption per passenger is becoming relative slight when the passenger load-ratio is larger than 60%. The relationship between the energy consumption of train movement and its technical speed is in the shape of U. The energy consumption of train movement is minimal when the technical speed is at 30 km/h. While the energy consumption is increased every 15% when there is a 10% increment of technical speed.(5) Selecting a reasonable and sustainable target speed should consider train operating time and train movemet energy consumption in the transport organization mode. Thus the paper propose a mothed of selecting target speed considering both train operating time and train movement energy consumption based on fuzzy comprehensive evaluation model, and a case in conducted to demonstrate the effectiveness of the method.(6) Analysis the structure importance of energy consumption in urban rail transit system and the correlative degree of the energy factors, by applying the combination of Grey correlative degree and Analytic Hierarchy Process (AHP). The results are described as follows:Train weight, traction power transmission efficiency, train auxiliary device is the most important factors which impact the energy consumption of the whole urban rail transit system drastically; and train control strategy such as train speed uniformity and looking forward distance, train formation as well as train technical speed impacts the system energy consumption greatly; The maximum grades of the track profile, light devices in the station, average inter-station distance and the station power equipment is also impacts on the system energy consumption; Minimum radius of the track curve also impacts on the system energy consumption of urban railways, which is relatively slight.