Phase-variable modelling of saturated reactor compensators with particular reference to long-distance transmission

Analysis conditions which are based on balanced parameter sets and balanced operating conditions in power networks are often consistent with the requirements of a range of steady-state evaluations, but circumstances arise in which they are restrictive, and where it is required instead to retain in analysis the identity of the individual phases. It is then possible to represent given load distributions among the separate phases, together with asymmetries in the impedance and admittance parameter sets of system elements, particularly those of power transmission lines. The specific developments of the present paper are principally in this context. They are those of modelling in computer analysis for the forms of reactive-power compensator which are based in their operation on saturating reactors. For this type of compensator, a comprehensive phase-variable representation is derived, and procedures are developed for including it in Newton-Raphson network analysis in which saturated reactor compensators are one particular type of network branch. The complete analysis scheme makes provision for any number of compensators individually to be represented at any nominated network nodes, and also for where two or more compensators operate in close-parallel connection at one location. Included in the representation of parallel connections is the case where current-equalising connections are made between the slope-compensating capacitor circuits of two or more separate compensators. All aspects of the advances in modelling methods of the paper, together with their programming implementation, are validated on the basis of extensive correlation studies in which the results of computer analysis are compared with test recordings from direct measurement, for a range of typical operating conditions. The paper concludes with examples from a representative design study which involves transformer-coupled compensators at separated locations, and where two compensators at one of them have- internal parallel connections.