Tadeusz GLINKA, Marcin GLINKA
The voltage wave distribution on a transformer winding during lightning incidents
Transformers and measuring transformers connected to a grid are exposed to various types of surges. Surges in a power grid are generated by lightning strikes and during various types of switchings. Surge waves are of a very short duration and this causes that the voltage distributes unevenly along the winding. Shown is that the maximum voltage gradient appears at the beginning of the winding and that this gradient depends on the coefficient α = [Cg /Cz ]^0.5, where Cg is the capacity of main insulation and Cz is the capacity of winding insulation.
Keywords: transformers, voltage disturbances, insulation system
Przemysław GAWLICZEK, Maksymilian PRZYGRODZKI
Practical aspects of selected UHV power transformers operation
Presented are selected elements of a group of 250 and 160 MVA (voltage ratio: 220/110 kV as well as 400/220 and 400/110 kV) transformers maintenance and operation processes. The units, which have various age and constructional parameters, work in the southern part of the Polish power system. Attention is turned to the dependence of parameters monitoring intensity (especially of DGA diagnostics) on the construction age with the conclusion that the younger the units, the smaller constructional margins, thus the growing purposefulness of more often monitoring.
Keywords: large power transformers and autotransformers, operation and parameters monitoring
Jakub NIECHCIAŁ
Nuclear power vs renewable energy (a voice in the dispute)
Nuclear energy is nowadays stigmatized as a threat to environment and a non-effective form of obtaining electricity, especially in reference to the promoted renewable power industry. The article is dedicated to the comparison made between nuclear power plants and renewable energy sources. Presented are advantages and disadvantages of particular solutions. The author is trying to answer the question: „Is the renewable power industry able to stand for the conventional power plants in the nearest future?” Presented are also the most common myths concerning that very interesting branch of science, shown are its advantages and disadvantages and all this is confronted with renewable energy sources (wind, sun, geothermal).
Keywords: nuclear power industry, renewable energy
Edward MAGIERA, Tomasz SŁUPIK
Production management – identifiaction, optimization, planning
Many definitions of a production management can be found in the literature concerning this process. Presented are here, on the basis of one of these definitions for eneterprises dealing with energy production, transmission and consumption, some structured actions that should be taken with the aim to achieve the best production and economic effects as well as to be prepared for disturbances and minimization of possible losses resulting from more and more complicated, for instance by a growing share of RES, power supply structure of the Polish power system. Defined is, basing on an experience gained in enterprises of various production profiles, an exemplary technical architecture of a production management system oriented on basic actions improving business indicators of conducted activity which are identification, optimization and planning.
Keywords: production management, technical architecture of a production management system
Robert CHOLEWA
Efficiency or elasticity of generating units – a report from measurement experience
Made is an analysis of power units working with low loads on the basis of measurement experience. For the work of 220 MW units that were subject to this analysis there were no limitations during the load equal to 40% of the rated load. There was encountered only the limitation in the work of the SCR catalytic flue gas denitrification installation as the flue gas temperature upstream the converter was too low in all the tests made. But the work with the load equal to 40% of the rated load is accompanied by the increase of the net specific fuel chemical energy consumption by 12,5-13,8% in relation to the rated load. That increase can be lowered by about 1% through limitation of the number of working devices (mill units, condensate and feeding water pumps) and additionally by another 1% through variable regulation of air and flue gas vents speed. Also using the possibility to modify a turbine incoming steam pressure enables to improve (up to 0,5%) the operation of power units working with very low loads.
Keywords: power units work, low loads, measurement experience
Kazimierz ZAMOROWSKI
The need to control boilers and auxiliary equipment changing working parameters as the result of changes in load of power units with central control
Operation with the use of APFC imposes frequent changes of boiler loads causing changes of their parameters and the need of working in some other variable point of characteristics. Discussed is the influence of load changes of centrally controlled power units on the obtained working parameters of a boiler and auxiliary equipment and emphasized is the need to control them in aspects of: changes in working parameters as the result of steaming capacity change with the stable work in the entire load control range (from maximum to minimum power), changes in dynamic working parameters and extension of a load control range. Described is also the influence of changes in a boiler working parameters on the achieved operational factors (efficiency, auxiliaries energy consumption). Given are examples of obtained characteristics as the function of a boiler load.
Keywords: centrally controlled power units, load changes, working parameters of a boiler and auxiliary equipment
Jacek M. DUBRAWSKI
South Korea – a country that knows how to make it without own natural resources
South Korea is one of the biggest energy importers in the world. But, as it practically does not have any natural resources and 97% of its demand for primary energy is covered by imported fuels, the issue of energy security and prices of energy raw materials are a strategic problem for this country. Predominant objectives of Korean energy policy is diversification of raw materials sourcing sites, increase in its own production by way of buying shares in coal mines, oil and natural gas fields abroad, extension of nuclear power generation and development of services in the energy sector like crude oil processing, constructing refineries and exporting nuclear reactors.
Keywords: South Korea, import of energy raw materials, Korean energy policy