EHV and UHV Line Loadbility Dependence on Var Supply Vapability

Optimization algorithms for power system operation and planning employ EHV and UHV line loadability limits as well as var supply limits. Traditional line loadability limits are based on stability limits which assume infinite var supply capability. This paper shows the critical dependence of line loadability on var supplies and presents a method to compute line loadability limits that are consistent with var supply limits. As such the limiting quantities are suitable for optimization algorithms which utilize both line loadability and var supply constraints.