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.

The paper presents the results of few numerical applications for sustaining the idea of unbalancing transversal capacitive compensation like a method for balancing the load of the electrical distribution networks and consequently to increase the voltage quality and the efficiency. The load balancing, analytical described by the annulment of negative component of the currents on the load phases, is possible by using a three-phase shunt compensator in delta connection, which contains only capacitive susceptances and/or inductive susceptances. The authors sustain in this paper the advantages of using simplified compensators, which contains only capacitive susceptances, and which, in the most of practical situations allows the total or almost total balancing of the load. The structures of this compensators will conduce to low costs, even when this are used for an on-line compensation, the capacitive susceptances control is individually depending on the nature and the dimension of the load unbalancing. The paper contains numerical examples regarding a three-phase low voltage network.

Due of its significant economical impact, Power-Quality (PQ) analysis is an important domain today. Severe voltage distortions affect the consumers and disturb their activity. They may ...

The paper presents a virtual laboratory for studying power quality events like three-phase voltage dips, which is used by students to learn and test their knowledge about the subject. The virtual laboratory is needed because in real life, in power quality domain, it is very difficult to generate power quality events in order to see the effects or to analyze their characteristics. The virtual laboratory is designed to give the students the possibility to learn first the theoretical aspects of the subject, then to apply the knowledge they accumulate to several signals, in order to get the characteristics of the event and in the end to test their obtained results with signals characteristics. There are two major advantages of using the virtual laboratory: first is that the students can see different events, with different characteristics, and in this way, they understand better the phenomenon; and the second is that a classical laboratory for studying three phase voltage dips is very expensive, the main elements (programmable voltage sources) having a very high cost

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 400kV 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