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 Vancouver ALRT (Advanced Light Rapid Transit) system. The converter model has been revised to accurately simulate a twelve-pulse parallel-connected converter station with inversion capability. A model and algorithm to simulate the operation of wayside braking resistors called automatic assured receptivity units (AARUs), 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. Several simulation case studies are examined that are based on typical Vancouver operating scenarios. Performance comparisons between six and twelve-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 yields accurate solutions in a reasonable amount of CPU time.<>