Special protection systems based on generator tripping are implemented to protect power systems against the loss of synchronism following extreme contingency events. Such a countermeasure is particularly effective when the circuit breakers of the tripped generators are opened soon after the fault is cleared. This paper presents the new method that enables quick real-time predictions of transient instability and the number of generators that must be tripped. The proposed method uses only local measurements and is based on the quick prediction of the magnitude of the power-angle characteristic. The proposed method has been validated by simulation tests performed for a large-scale real power system and detailed models of power system elements.

The aim of this work was to develop a parameterized analytical and FEM (Finite Element Method) model of a switched reluctance motor. The developed analytical model was used to assess the performance of these types of motors, and is determined to be a tool for comparing and evaluating switched reluctance motors of various designs. The aim of the work was also the systematization of knowledge related to the operation, structure and methods of determining the static electromagnetic torque generated by switched reluctance motors. The FEM model (ANSYS) was, also, made in order to verify physical phenomena occurring during operation of these motors. Four laboratory tests were executed as part of the work prototypes of switched reluctance motors built at Warsaw University of Technology. A parameterized analytical model was developed and implemented in MATLAB. The model operation tests were conducted and as a result, the characteristics describing the dependence of the electromagnetic torque as a function of the current and the position of the rotor were obtained. The model was validated by confronting the analytical calculations supported by FEM simulation results with the measurement results. The usefulness of the results obtained with the use of the procured models was assessed.

In this paper, a detailed three-dimensional, transient, finite element method of fuse link NH000 gG 100 A is proposed. The thermal properties during the operation of the fuses under nominal (100 A) and custom conditions (110 and 120 A) are the main focus of the analyses that were conducted. The work concerns both the outside elements of the fuse link (ceramic body) and the elements inside (current circuit). Both the distribution of the electric current and its impact on the temperature of the construction parts of the fuses during their operating mode have been described. Temperature distribution, power losses and energy dissipation were measured using a numerical model. In order to verify and validate the model, two independent teams of scientists executed experimental research, during which the temperature was measured on different parts of the device involving the rated current. Finally, the two sets of results were put together and compared with those obtained from the simulation tests. A possible significant correlation between the results of the empirical tests and the simulation work was highlighted.

In the paper power system digital relay test types are presented. Different types of analysis to which relay communication systems should be submitted are described. Among them the following can be enumerated: communication control board, communication interface between the device and the local monitoring PC, communication monitoring systems between protective devices. Also a particular attention was paid to the description of tests which should be performed on network-based communication systems (i.e. protection devices using the UCA protocol) both on site and in laboratory conditions. Moreover test procedure of UCA-based devices and the laboratory bench destined for network-based device testing are described. Finally some test examples and their results are presented with the appropriate comments.