Transmission Line Loadability: Capability Charts Validation by Experimental Power Measurements on HVAC Insulated Cables, and Overhead Lines

For any power line, the capability charts are graphical tools in the P-Q (active-reactive power) plane defining all its possible transmittable power. Their first formulation dates back to 2005, however, in this paper they are experimentally validated by means of long-term (3 years) measurements of the transmitted complex powers of one of the longest HVAC submarine insulated cable (IC) interconnecting Italy and Malta and of a HVAC overhead line (OHL) interconnecting Italy and Austria called Soverzene-Lienz. In order to allow these comparisons, improvement and generalization of the above-mentioned capability charts are necessary. Therefore, the paper presents an updated and enriched capability chart definition including all the possible operational constraints, not considered before, i.e., physical feasibility, voltage drop, voltage limits, and maximum shift angle. Then, an analytical validation of this novel capability charts is presented by exploiting an application of the Ossanna’s theorem. The power of these capability charts lays in the immediate visualization of the loadability of any power line, even equipped with compensation systems (both series and shunt).