Ryszard BARTNIK, Waldemar SKOMUDEK, Anna HNYDIUK-STEFAN, Aleksandra OTAWA
Universal diagrams used in quest for the optimum strategy of investing into heat sources
Unit costs of heat production for district heating depend on manufacturing technology. With the use of the elaborated and presented here diagrams one can – with the given fuel and electric energy prices as well as environmental charges including the purchase cost of CO2 emission certificates – select the most advantageous heat production technology i.e. the one of which the unit production cost is the lowest. As it can be seen from the presented here calculation results, the lowest unit heat production costs can only be obtained with the help of the lowest possible investment costs and the lowest fuel price as well as by the highest price and the largest amount of electric energy cogenerated with heat (the revenue from sale of electric energy produced in cogeneration is the so-called avoided cost of heat production in CHP plants) i.e by achieving the highest value of the annual cogeneration factor σR. At the present moment the cheapest fuel is coal and, in terms of investment costs, the heat generating plants. So, wherever heat consumption by local citizens is possible, electric power plants should be adapted for cogeneration work. It is by far the cheapest heat source for district heating and the economically acceptable distance from a CHP plant to consumer clusters (towns) is as much as 60 km.
Keywords: heat production technologies, optimum strategy of investing into heat sources
Eugeniusz RUSIŃSKI, Artur GÓRSKI, Jerzy CZMOCHOWSKI, Grzegorz PRZYBYŁEK, Michał PADUCHOWICZ
Evaluation of technical condition of a OR45 boiler drum in the area of downpipe nozzles
Evaluated was technical condition of a OR45 boiler drum shell in the area of outlet openings of downpipe nozzles. With the use of visual and magnetic particle methods performed were non-destructive tests to detect surface damages of the boiler drum and material discontinuities (cracking) in the crucial welded joints of its components [1,2]. Subsequently, with the use of the finite element method, carried were thermal and mechanical calculations to determine the stress state of the steam separator during its standard operation as well as to assess its impact on the occurrence of the detected discontinuities [2].
Keywords: OR-45 boiler, boiler drum shell, downpipe nozzles
Kinga WESOŁOWSKA, Sławomir BIELECKI
Review of methods applied in energy efficiency analyses
There are many methods that can be applied to assess the energy efficiency. However, when there is a need to select one of them it is advisable to consider not only the effect that is intended to achieve but also the amount and quality of data available to analyse. Some of these methods for instance, like “pinch”, enthalpy and exergy analysis or thermoeconomics need a special range of data. So, they are mainly dedicated to be used in power and industrial sectors where the constantly monitored production process is sufficiently well metered. Mehotds like LCA, VSM or DEA are more general and universal, so they can be applied in trade or service as well as in specialistic sectors. These techniques are often used for projection of effects of planned investments or modernizations. Additionally, some of them, beside the assessment of environmental aspects connected with the system of products and services, define also ways to reduce threats to natural environment. But all the methods have one thing in common – they lead to reduction of waste and in the same way they contribute to more effective use of raw materials.
Keywords: energy efficiency, analyses and efficiency assessment, review of methods
Jacek WASILEWSKI, Krzysztof KARKOSZKA, Zbigniew LUBOŚNY, Piotr RZEPKA, Mateusz SZABLICKI
Investigation of the impact of synthetic inertia coming from wind sources on the dynamics of a domestic power system working asynchronously in relation to the neighbouring transmission systems
It is expected that in the next few decades there will be observed a growing share of renewable sources, including wind and photovoltaic ones, which value of the generated active power in a natural way does not react to frequency changes in a system. The considered here scenario implies critical working conditions of a domestic power system (DPS) i.e. asynchronous work of a DPS in relation to neigbouring systems in conditions of minimum load and maximum wind generation. For this scenario a dynamic model of a DPS had been elaborated in the range of electromechanic phenomena. Simulation results, obtained from the elaborated DPS model, enabled the assessment of a DPS frequency response to the given power loss taking into account fitting power stations with synthetic inertia systems, changes in parameters of a DPS system and its spatial configuration on the territory of a country.
Keywords: wind power stations, synthetic inertia systems, DPS dynamics
Andrzej WARACHIM, Janusz JURASZEK
New solutions in modernization and expansion of MV distribution network
Functioning and evolution of smart type solutions in overhead and underground MV networks is relevant to proper functioning of the whole power system. New nods of the network are already designed with consideration to new technologies. Development of these technologies makes it necessary to anticipate necessity of modernizing not only the already used objects but also the ones being at the stage of functional analysis still ahead of design stage. Special attention is paid here to aspects of MV network nods modernization indicating possibilities to adapt new technologies. Ensuring controllability and observability of an object is a prerequisite for its proper functioning in future. Smart technologies should take into account abilities of primary circuit devices that ensure conducting real actions in a system. Possibility to measure current and voltage in a smart type network including statistical analysis of incidents, faults and variability of supply parameteres is relevant not only for protections and supply quality analyses but also for applying smart type transformers with remote voltage control. Ensuring cybersecurity of smart type MV networks is a growing and often unperceived problem. Industrial infrastructure is becoming more and more the object of interest for cybercriminals which can take the advantage of SCADA systems vulnerabilities and the lack of their proper protection.
Keywords: overhead and underground MV networks, modernization and expansion of networks, evolution of smart type solutions
Sławomir CIEŚLIK
Design of photovoltaic systems in prosumer microinstallations
The definition of a prosumer clearly emphasizes the idea of electric energy production for one’s own needs. It does not say a word about the sale of electricity but about a compensation for the surplus energy fed into the grid in the form of consumption of energy from the grid in some other time and in the agreed amount depending on the fed energy. Main attention was focused here on two important aspects of design and functioning of PV systems in prosumer microinstallations. The first is the answer to the question: How to determine the installed power of a PV system? The second one is the justification of the choice whether the electronic power converter should be a single- or a three-phase one. Given are results of a theoretical analysis concerning the work of prosumer microinstallations with PV systems in a given range. Shown are also selected results of experimental investigations of such systems and especially of the ones working in conditions diverging from the set standards.
Keywords: prosumer microinstallations, renewable energy sources, photovoltaic systems, electric installations