外文翻譯---預(yù)測鐵路供電系統(tǒng)工作模式的方法和工具(文件)
【正文】 Switching to onesided feeding when one railway substation is down. When one substation falls off, it can also result in a brief break in train traffic. Trains in this case can be accumulated at one of the stations. In order to repair this omission when the traffic is restored, the trains are sent with minimum possible gaps. This mode is called full use of carrying capacity of a railway section. Thus, on design stage heating of the traction wire should be checked in two conditions: * separate feeding of tracks on double track zones * train traffic with minimal time intervals between trains Apparently, the currents of two adjacent railway substations rise significantly when onesided feeding scheme is launched. Yet it should be 9 impossible for these currents to hit the maximum limit, otherwise the traction work wire will experience a breach in mechanical durability. Increase of currents in traction work not only plicates power supply system working conditions, but also causes high electromagic impact on munication lines located close to the railway. The voltage losses increase, too. It makes sense to assume that the minimal voltage level in traction work will be experienced in proximity of the switched off substation (at the end of console feeding zone). Uncontrolled drop in voltage level can lead to disconnection of lootives. Therefore it is particularly important to predict how the power supply system will operate in the breakdown mode. A breakdown mode cannot hold on for long (it usually takes up to several hours). It is possible to limit the number of trains moving inside the inter substation zone and to increase time intervals between trains. With a model which takes the section profile into account, it is possible to research breakdown modes for every single substation. The model calculates voltage levels in traction work and currents along the whole length of it. It is also possible to change train speed and time intervals between trains ? . During simulations, the model counts the voltage on each of the electric lootives and chooses the minimum. The minimum value is then pared to the allowed absolute minimumif the voltage is too low, the time interval is increased by one minute: 11 ???? ?ii (1) Then the model starts the simulation over. This stepwise optimisation of time intervals between trains yields in the time interval which is minimal acceptable for a fixed train speed. Another oute is an array of currents on all elements of inter 10 substation zone (with an accuracy of 3 km). These currents can be used to calculate electromagic influence on adjacent munication lines. Model algorithm The model runs in an Intemet browser. All data available from the railway experts about the section profile is already incorporated in it, as are the abovementioned formulae and methods. First, the user chooses the inter substation zone from a predefined list of zones on which the data is available to the application. This choice determines all train currents and positions of intermediate stations. Then, it is possible to provide additional input data: fix the train speed, choose the number of trains in a pack, minimum time interval between trains, traction work type, its resistance, displacement interval, etc. Data is checked for validity, and the simulation process starts. visualising every step. Every minute a moment scheme is calculated: the current of each substation and the voltage on each lootive are determined, saved and pared to the allowed bounds. When the last train leaves the inter substation zone and there are no more trains waiting to be let in. the simulation stops. All simulation outes such as maximum voltage loss, maximum current and the time interval between trains that meets all the conditions are displayed. This is how the model works for the simplest possible configuration. We have dealt with more plex real life situations, for example, they can bine double track and single track zones, they can have more than two d
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