Ryszard BARTNIK, Anna HNYDIUK-STEFAN, Berenika BARTNIK
Measures and mathematical models in continuous time recording of economic efficiency analysis for power industry investments, valuation of heat and electricity market fair value and a market value of power companies
Presented are records of NPV, IRR and DPBP measures as well as elaborated with their help mathematical models in continuous time. Attention is called to the fact that such records have an advantage over discrete records as they allow carrying out analyses of mathematical models with the help of differential calculus. Without that it would be at least very difficult, if not impossible, to notice various relations showing how their values are influenced by, among others, power technologies and power efficiency of individual devices or a demand (annual output) for heat QR and electric energy Eel,R as well as relations and scope of price changes of energy carriers.
Keywords: economic efficiency of power industry investments, continuous time (not discrete) records of measures and mathematical models
Tadeusz GLINKA, Andrzej SIKORA
Measurements of a transformer turn-to-turn insulation capacitance and resistance
Values of capacitance Cz and resistance Rz of a transformer windings turn-to-turn insulation are used in an analysis of a voltage wave distribution across the windings during overvoltages as well as in an insulation system diagnostics. Presented is the procedure for measuring capacitance Cz and resistance Rz of a transformer winding turn-to-turn insulation. The measurements were performed on a 160 kVA dry-type transformer.
Keywords: transformers, insulation capacitance, insulation resistance
Paweł SZEWCZUK, Łukasz BOLEWSKI, Marek SZKODO
Influence of geometry disturbances on an expulsion process in a borehole annular space
Analysed annular space geometry situations reflect the state of a borehole, without taking into account the possibility of borings sedimentation on the walls of a borehole or of a pipes column, or of geometry changes caused by the presence of unstable packet-loamy layers. Discussed are also expulsion simulation results for ten fluid domaines representing idealized situations of annular space geometry disturbances. Changes in annular space geometry have considerable negative impact on the drilling fluids expulsion process. If a level is found, where during a borehole diameter measurement with a BDG a significant annular space clearance reduction is detected, it is recommended to carry out operations having in aim reconstruction of the desirable geometry before cementing begins.
Keywords: boreholes, annular space geometry disturbances, cement coating tasks
Łukasz BOLEWSKI, Paweł SZEWCZUK, Marek SZKODO, Marian KIEŁT
Borehole calibrator and its influence on a borehole cementing quality
Sealing off reservoir rocks by well cemented casings is one of the most important operations in hydrocarbon extraction. Failure to obtain a proper seal can cause environmental pollution that would need to be cleared up in costly salvage and remedy works. There could even arise a necessity to pay financial compensation for caused damages. For these reasons it is crucial to properly solve all technological problems, taking into account numerous factors covering design and cementing stages of the whole process. For that purpose a scientific team from Politechnika Gdańska, financed in the frames of the “Blue Gas” program conducted by Narodowe Centrum Badań i Rozwoju, has developed a device called “borehole calibrator”. Results of tests performed on shallow holes have confirmed effectiveness of this tool.
Keywords: underground hydrocarbon extraction, cased boreholes, rock levels sealing
Waldemar DOŁĘGA
Modern substations in cities
Described are selected aspects referring to realization of building processes and applied construction solutions for modern substations in urban agglomerations. Presented are substations that can be found in such agglomerations and determined is the role they play in complex urban local power systems. Discussed are formal and legal conditionings concerning substations building in cities. Analysed are construction solutions applied in such substations.
Keywords: power substations, urban agglomeration, construction solutions
Wojciech LUBICKI, Maksymilian PRZYGRODZKI
Probability distribution functions of forces (PDF) as an element of development planning methodology
Deterministic criteria are the key element of the present planning methodology for transmission and distribution networks development in Poland. Transmission network in a planning process includes 400, 220 and 110 kV networks, from which the last one is formally classified as a distribution network (because of its ownership structure) though it cooperates as the closed one with other networks. From a planning process point of view both networks should be analysed together. During previous CIGRE session mentioned were some, applied in Poland, methodological improvements that are connected with with an optimum distribution of forces (OPF). That can be regarded as the first step to these improvements while the next one can be connected with PDF. Preliminary scientific research has been carried out in this field and a comparison has been made between various PDF calculation methods. Probabilistic approach is broadly applied in the world though the scope of its application is very diverse. It covers wide area from power demand to manufacturing sector and also includes issues concerning availability of network infrastructure and probabilistic criteria. Generally three types of approach can be observed: approximation, analytical and numerical. The most popular in the world is the numerical one because of a quick IT technology development and relevance of obtained results. For a transmisson system development planning in Poland a probabilistic approach could be considered but with regard to approximation and analytical methods limitations, numerical methods should also be taken into account. An open question remain numerical simulation methods – Monte Carlo, layer methods or others.
Keywords: development planning, transmission network, probability distribution functions of forces (PDF)