Protection Analysis And Summary Of Traction Drive System For AC Electric Locomotive

With the rising demand of the global railway transportation, electric locomotives acted as the supporter of rail transportation is tending to become higher speed and heavier load. One the one hand it brings good opportunities to expand for the manufacturer, On the other hand it requires manufacturers to provide locomotives with higher security and reliability. Research on locomotive protection, there is few scholars researching in the protection of whole locomotive, they have only focused on a device or a particular aspect of locomotive, which have not formed a systematic solution to locomotive protection. With the rapid development of railway industry, different of AC locomotives are applied widely. However deeper study about locomotive system protection is not enough, which has become one of the key factors for the safety of locomotive.This article has analyzed the principle of operation of the locomotive. It contains main transformer, main converter, traction motor, auxiliary transformer, high voltage breaker, line voltage and current. Based on the structure of main circuit of the AC locomotive’s traction system, it has deeply researched in the protection principle of whole system.(1) According to the working charteristics of pantograph,it has introduced methods which considered the time of lifting pantograph and pantograph pipe pressure as the condition of the pantograph’s protection measures;(2) Main transformer oil, as the cooling medium of transformer, is one of the important factors affecting work of the main transformer. So the temperature of the main transformer oil is considered as main discussed target. This article has also described other measures of main transformer protection, such as buchholz relay and Pressure Release Valves. Similarly, the temperatures of the cooling medium about main convertor, auxiliary transformers and traction motor should be mainly considered as its protection measures;(3) During locomotive’s running, too high net-voltage can affect locomotive’s insulating property and normal working. Too low net-voltage may cause that the locomotive power can not play its traction function properly. The above situation will take negative affect to the transportation production. So net-voltage protection of the locomotive was divided into two parts:over-voltage protection and under-voltage protection;(4) In the circuit on side of overhead contact line, differential protection, over-current protection, and instantaneous over-current protection constitutes a complete protection system relating to the current on side of overhead contact line. This article described a current protection measure and the setting method of the protective value; (5) Finally, taking HXD1electric locomotives for example, it describes the test methods for locomotive protection.Based on the locomotive’s development, this article has researched protective function of AC-locomotive traction system from the view of ensuring the stability and safe running of the locomotives. In the while, this article combines the theory of system protection design for AC-locomotive and manufacturing experience of locomotives which were made by CSR in the recent yeas, such as HXD1, HXD1B, HXD1C, and has formed a set of relatively perfect and reliable scheme of locomotive protection, which is able to help to develop and design new type of locomotive for reference.