Study on the Dynamic Performance of High-Speed Railway Catenary System With Small Encumbrance

The catenary system is the only source of power for high-speed railways, which carries the electric current to be collected by a pantograph mounted on the train roof via sliding contact. The height difference between the contact wire and the messenger wire at the support is called the encumbrance of the catenary, which is normally restricted to satisfy the demand of wind protection in an open environment and reduction of clearance in the tunnel. The reduction of the catenary’s encumbrance consequently decreases the droppers’ length and affects the interaction performance of the pantograph–catenary. This article is the first attempt to make sense of the pantograph–catenary interaction performance with small encumbrance. Firstly, the compression characteristics’ tests of short droppers of different lengths are performed. Based on the test results, a nonlinear dropper model that considers the tension–compression property is proposed. Then, a pantograph–catenary model integrated with the modified dropper model is built. Taking a China high-speed railway as an analysis object, the effect of encumbrance on the dynamic performance is investigated. The results demonstrate that the traditional dropper model cannot fully describe the dynamic behavior of the catenary with small encumbrance. The deterioration of the dynamic performance of the small encumbrance catenary is mainly caused by the compressing force generated from the compressed droppers. When the length of the shortest dropper is less than 400 mm, the interaction performance of pantograph–catenary deteriorates significantly. On the contrary, when the length of the shortest dropper exceeds 900 mm, the encumbrance does not have a distinct implication on the dynamic performance. It is suggested that the shortest dropper length should exceed 400 mm to ensure acceptable dynamic performance.

I. Introduction

The catenary system is a cable structure erected above the track to provide electrical current to the electrified train via a pantograph. The clearance requirement of the catenary depends on the encumbrance of the catenary. The encumbrance is defined as the vertical height between the contact wire and the messenger wire at support, as shown in Fig. 1. In tunnels, a smaller encumbrance is preferred, as it can result in a decreased tunnel Section and excavation volume, which reduces the construction costs. In coastal areas, the small encumbrance is also conducive to the wind load. However, the reduction of encumbrance may change the dynamic performance of the pantograph–catenary. The acceptance of the interaction performance requires to be re-checked when designing a catenary with smaller encumbrance. Fig. 1.

Encumbrance of the catenary system.