Ryszard BARTNIK, Zbigniew BURYN, Anna HNYDIUK-STEFAN
Comparative analysis of economic effectiveness of the operation of a power unit with supercritical parameters with its operation in the oxy-fuel technology
This paper reports the results of a comparative analysis regarding economic effectiveness of the operation of a condensing power unit with supercritical parameters with its operation in the oxy-fuel technology. The application of the innovative technology of oxy-fuel process is imposed by the necessity to fulfill EU regulations with regard to reduction of CO2 emission into the atmosphere. The calculations were performed by comparing the specific production cost of electricity in the two designs and using economic analysis measures, i.e. NPV, IRR and DPBP.
Keywords: oxy-fuel, CO2 emission, power unit, specific cost of electricity production, NPV, IRR, DPBP
Maksymilian PRZYGRODZKI, Piotr RZEPKA, Mateusz SZABLICKI
Criteria and decisive algorithm of a zero-sequence current directional ground fault protection on HV and LV overhead lines
Characterised is a decisive algorithm implemented in zero-sequence current directional ground fault protections on HV and LV overhead lines. Described is functionality of overcurrent and directional decisive criteria. Presented is a structure of a way to elaborate the protection decision. Included are comparative analysis results of how the selection of a method to determine the voltage and current zero-sequence component impacts the speed and accuracy of earth-fault detection by protection.
Keywords: zero-sequence directional protection, decisive criteria, earth-faults on HV and LV overhead lines
Sebastian BORUCKI, Jacek ŁUCZAK
Assessment of the impact of an acoustic signal power spectral density frequency selection on partial discharges basic forms classification efficiency with the use of data clustering method
Presented are assessment analysis results of the impact that spectral density frequency selection of the generated by partial discharges in an oil-paper insulation acoustic emission signal power has on application efficiency of the data clustering method for identification of these discharges. Within the framework of the conducted research a quality analysis was carried out of frequencies from an experimentally selected range of 10 kHz to 990 kHz, then of the established as a result of previous studies Ward data clustering method and also of a similarity function (metrics) in the form of Mahalanobis distance. The aim of the conducted analysis was to find a pair of frequencies for which the highest reconstruction degree of original measurement data distribution could be reached in the way of data clustering. Appropriate analyses and simulations were conducted with the use of Matlab computing environment and procedures that are accessible there. Analysed were also results of measurement series of acoustic emissions (EA) generated by three basic forms of partial discharges (WNZ) which were obtained in laboratory conditions by using spark gap systems modelling oil-paper insulation faults in power transformers.
Keywords: oil-immersed power transformers, data clustering research method, acoustic emission signal identification
Rafał KRUPIŃSKI
Floodlighting of a city architectural objects
Basic aim of object illumination in cities is mainly floodlighting of the most important or exceptional buildings, improvement of aesthetic image of a city during late evening and night hours as well as the safety reasons. Given are criteria of object selection for illumination and specified are two methods of illumination design – field tests with the use of floodlighting equipment and computer simulation of a virtual object model lighting. Presented are several examples of illumination designs including the church of Franciscans Friars of the Renewal in Węgrów, tenement house of Mr. Michał Szelechow in Warsaw, museum of the King Jan III Sobieski Palace in Wilanów and the academic campus of Gdańsk University of Technology.
Keywords: architectural objects in cities, floodlighting of objects, methods of illumination design