A new novel power electronic circuit to reduce stray current and rail potential in DC railway

Calculation of remote effects of stray currents on rail voltages in DC railways systems

“…Since the isolation of the sleepers is not perfect, there will always be leakage currents, di(x). At a certain distance from www.ietdl.org the substation and because of its influence, such leakage currents reverse their direction, that is, the current is no longer lost to the earth, but emerges from it and returns to the substation via rolling rails [11][12][13][14][15]. Stray currents can be limited in different ways, including electrical circuits based on power electronic semi-conductors [3][4][5][12][13][14], different earthing schemes [3,4,9,13], reducing specific rail resistance, R′ R , increasing rail-to-ground specific conductance, G' RE [8,13,14] and reducing substation separation [8,11].…”

“…Therefore in a normal DC traction system there will always be a significant percentage of stray currents which flow through the earth out of the rails, because the isolation level of the railway lane is quite high, but not infinite [1][2][3][4][5][6][7][8][9][10][11]. Stray currents leak into the earth until they finally emerge at the earthing terminal of the substation, fulfilling Kirchhoff's first law [10][11][12][13][14][15].…”

“…The main effect of rails potential and the leakage currents in DC systems is the degradation of metallic infrastructures because of electrolytic corrosion processes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], with the consequent economic cost of maintenance that they entail. For this specific reason, in DC traction systems there must be a strict separation between the feedback circuit and earthing systems [3,4,6].…”