Characterizing the Steady-State Performance of AC Lines Through a Dimensionless Universal Model

Abstract

This paper revisits the AC power line model. Based solely on three dimensionless parameters, a universal electrical model is first developed, which is valid for any kind of power line (overhead, underground/submarine or gas insulated), irrespective of its rated voltage and length. Then, by neglecting the shunt losses, compact expressions are obtained in terms of the two remaining parameters for all electrical magnitudes characterizing the steady-state behavior of any line, such as real and reactive power flows at both ends, losses, charging current, transmission capability, etc. As a result, universal parameterized curves are also provided, including the well-known PV and P- $\delta $ curves. Moreover, numerical ranges of defining parameters are obtained for a diversity of present or future line arrangements, rated voltages and lengths, which are then represented as clusters of points on the universal curves. Beyond educational purposes, the proposed formulation and the associated characteristic curves can be useful, at the planning or design stages, when a certain degree of parameter uncertainty is still present, in order to compare different designs, or when selecting the most suitable simplified model for a particular case study, before fully defining the line features (type of conductor, phase-to-phase clearance, type of configuration, insulation, etc.).

Keywords

• Charging current
• distributed-parameter model
• gas insulated line
• steady-state stability limit