In the last decades there have been great advances in electronic, information and communication technologies. Up to date, any of these advances have been implemented in electrical systems, but some difficulties have been encountered, particularly regarding to the integration of intelligent electronic devices from different manufactures into a centralized system. With the aim of solving the above mentioned problem, the standard IEC 61850 was developed to specify communication networks in substations.Read full article
Characteristics of voltage sags caused by faults in distribution networks depend on the design of the protection system and the coordination between the different protective devices. The presence of distributed generation (DG) changes the radial nature of distribution systems, so it can affect the performance of the protection system, and consequently the characteristics of voltage sags. In addition, DG will help to maintain the during-fault voltages of healthy phases.Read full article
Voltage control in networks with predominantly resistive coupling is most efficient when controlling the active power flow. By introducing a series connected inductor for a dedicated part of the network the coupling can be shifted to the inductive type. Hence the voltage in such sub-networks can be influenced by injection of reactive power. Furthermore harmonic distortions present in the main grid are reduced.Read full article
How sustainable is a kWh? What is the best technology to produce it? These questions are often asked and the answers are not clear-cut, as there are a lot of variables.
Therefore, Leonardo ENERGY has produced this eco-sheet to help clarifying the issue. The environmental burden of generating one kWh from 7 different energy sources is quantified. It shows that there is no silver bullet solution, but there are advantages to explore.Read full article
Wind turbines are a common source of electrical power generation in rural sites around the world. The power generated by a wind turbine at a given wind speed is a non-linear function of rotor speed. This results in a specific rotor speed for maximum power production at each wind speed. A control system incorporating a Pulse Width Modulated DC -DC converter has been designed to vary the load on the wind turbine thereby forcing it to operate at its maximum power point.Read full article
The paper deals with the general analysis of one part of the electromagnetic compatibility (EMC ) problem — the electromagnetic coupling applied in the field of power electrical systems as. The simulation analyses and practical measurements of the electromagnetic coupling are presented in part II . Obtained results confirm the correctness of the theoretical analyses and so they can be used for predictive stating of EMC quality of individual new electrotechnical products.
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Measurement investigations have been carried out for commutator dc motor with internal asymmetries. Construction of considered motor enables to realize the breaking of one rotor coil and shorting of two groups of rotor coils. Each group contains three rotor coils. The basis of study were signals: current and voltage of field winding, current and voltage of armature winding and velocity of the rotor.Read full article
There are many problems in practical diagnostics of high-power, quirrel-cage induction machines, operated in industrial conditions. These problems make the diagnostics a difficult matter. The problems appear already at the stage of gathering diagnostic signals. The only practically accessible signals are the currents on secondary sides of current transformers monitoring supply currents of separate machines.Read full article
A great deal of work is being done on the improvement of control through simulation of the electric drives used for various high-power purposes. The authenticity of the simulated results is based on the accurate modeling of the various parts of the electric drive system.Read full article
This paper presents a model based mathematical equations for control of torque and speed of a three-phase indirect vector controlled VSD-fed induction-cage motor that is controlled through the space vector modulated method. This enables a wide range of acceptability of the model for various values of load and various types and ratings of induction motors.Read full article