QENS-an enhanced version of the electric network simulator program

A commercially available AC/DC load flow program geared specifically to transit systems has been enhanced to simulate the peculiarities of the Vancouver Advanced Light Rapid Transit system. The converter model has been revised to simulate accurately a 12-pulse parallel-connected converter station with inversion capability. A model and algorithm to simulate the operation of wayside braking resistors automatic assured receptivity units is developed. The revised program, QENS, retains the separate AC and DC networks and uses a sequential method to obtain convergence of both networks while simultaneously satisfying the converter voltage and power constraints. Performance comparisons of 6- and 12-pulse converters are made, and the effects of regenerative braking into a nonreceptive power system are investigated. The Gauss-Seidel method used in the algorithm provides QENS with good convergence characteristics and consistently obtains accurate solutions in a reasonable amount of CPU time.<>