Power Quality Improvement for Egypt Subway Electrical Network

In Cairo METRO system electrical power supply, diode rectifiers are commonly used in the front end of a power converter as an interface with the electric utility. Rectifiers are nonlinear in nature and, consequently, generate harmonic currents into the ac power source. The nonlinear operation of the diode rectifiers causes highly distorted input current. The non-sinusoidal shape of the input current that causes a number of problems in the power distribution network. The distorted input current flowing through the system produces distorted voltages at the point of common coupling (PCC). Thus, the increased harmonic currents cause increasing total harmonic distortion (THD) in the input lines. The recommended practice, IEEE-519, and IEC 1000-3 have evolved to maintain utility power quality at acceptable levels. The proposed solution is based on converting the existing 12-pulse converter into 36-pulse converter by employing pulse multiplication technique. This method enables improvement of system power quality indices to be comply with the international standards. system modeling and experimental prototype arrangement are presented to validate the proposed solution.