DIAGNOSIS OF VOLTAGE UNBALANCE ON ELECTRIC RAILWAY SYSTEM

초록

The conventional researches on the voltage unbalance have dealt with connection schemes of the transformers used in AC AT-fed electric railway system and induced formulas to briefly evaluate the voltage unbalance in the system [2, 3]. These formulas are still being used widely due to their easy applicability on the voltage unbalance evaluation. Meanwhile, they do not take into account detailed characteristics of AC AT-fed electric railway system, being founded on some assumptions. The evaluation of voltage unbalance using two-port network model in areas, such as electric railway depots was carried out [4]. System of the depot was single track composed by only contact wire and rails. Hence, two-port network model is fit in electric railway depot. However, four-port network model is fit in general electric railway system composed by contact wires, rails and feeders. Four-port network model has two input ports, two output ports and a basic port. The proposed model is carried out to forecast power qualities at stages of designing and planning for the electric railway system. At this moment, the paper deal with the exact assessment of the voltage unbalance in lots of power qualities The paper proposes a new analysis model to more effectively estimate the voltage unbalance. Numerous distributed circuits in the electric railway system are composed by components. The entire system can be easily modeled by the combination of four-port representation of each component in parallel and/or series. Simulation results using the model are compared with field data, and it verifies the accuracy of the proposed model."