Load Flow Methods: Part I
The ϒ-matrix iterative methods were the very first to be applied to load flow calculations on the early generation of digital computers. They required minimum storage but, however, may not converge on some load flow problems. This deficiency in ϒ-matrix methods led to Z-matrix methods, which had a better convergence, but required more storage and slowed down on large systems. After the load flow is solved and the voltages are calculated, the injected power at the swing bus can be calculated. The chapter discusses the model for a ratio-adjusting type transformer. The impedance of a transformer will change with tap position. For an autotransformer, there may be 50% change in the impedance over the tap adjustments.