A Study of the Power Factor Improvement by Using Harmonic Filter in Busan Urban Railway Substation with Thyristor Rectification Method

Abstract

The electric power required to operate the urban railway supplies DC 1,500, V to the electric train through trolly wire. The rectifier which converts AC to DC has a rectification method using a diode and a rectification method using a thyristor. The thyristor rectification method is easier to adjust the trolly wire voltage than the diode rectification method. In addition, it is possible to reuse the regenerative electric power generated when the electric train stops, thereby helping to reduce the operating cost of the Urban railway operator and to reduce the greenhouse gas. However, the thyristor rectification method has a disadvantage in that the power factor of an urban railway substation is lowered because a harmonic current is generated during rectification and the reactive power becomes large. In this paper, we analyze the harmonic currents generated of Busan Urban railway substation system using thyristor rectifier, we propose an optimal harmonic filter to achieve a power factor of over 90% by simulation.