No abstract

No abstract

No abstract

The electrical power transmission is realised in most of the cases by overhead power lines long of hundred of kilometres and operating at different high voltage levels. The load of these overhead power lines is widely varying depending both on the evolution of consumers (the consumers load curve) and on the operating conditions of the power system elements. For experimental analysis of the operating conditions of transmission overhead power lines, the equivalent diagram П, T or Γ, generally symmetrical, are used. The paper presents the particular operating conditions of the overhead power lines: no load and short circuit, which are important in practice, because to their associated phenomena. A 400 kV overhead power line is modelled using MatLab Simulink and the above-mentioned operating conditions are analyzed. The presented model is used in teaching activity during the power grids laboratory lessons for power engineering students of our university. The paper includes the conclusions related to the studies and the detailed results.

Nowadays, improving the power quality at the Point of Common Coupling (PCC) between the consumers' installations and the distribution system operators' installations depends more and more on the use of specialized equipment, able to intervene in the network to eliminate or diminish the disturbances. The reactive power compensators remain valid solutions for applications in consumer and electricity distribution, in those situations when the criterion regarding the costs of installing and operating the equipment is more important than the ones related to the reaction speed or the control accuracy. This is also the case of the equipment for power factor improvement and load balancing in a three-phase distribution network. The two functions can be achieved simultaneously by using an unbalanced static var compensator, known as an adaptive balancing compensator, achieved by adjusting the equivalent parameters of circuits containing single-phase coils and capacitor banks. The paper presents the mathematical model for the sizing and operation of a balancing reactive compensator for a three-phase four-wire network and then presents some resizing methods to convert it into a balancing capacitive compensator, having the same functions. The mathematical model is then validated by a numerical application, modelling with a specialized software tool, and by experimental laboratory determinations. The paper contains strong arguments to support the idea that a balancing capacitive compensator becomes a very advantageous solution in many industrial applications.