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Paper deals with calculation and design of the heat pumps that are used for purposes of heating and cooling. Heat pumps are systems that draw heat from one source (earth, water, air or ambient) and transfer it to another. Their operation is described by Carnot circular process, in which thermal energy is taken from one body to working medium and then from a working medium to the heated body. Energy...
The members of the European Union turned their attention to renewable energy sources because of increasing energy demand, decreasing inland fossil fuel supply, raising and variable energy prices and concern about climate change. Within the European Union Hungary is in arrears to the other members using renewable energy sources. The objectives of the Hungarian energy policy go by the energy policy...
The history of mankind numbers about 500 thousand years and overwhelming part of this period of time we have been governed by natural light. The Sun was the only source of light. Try to imagine the world in which people wouldn't know the ways of getting light. When the sun was setting, all the life stopped, and people hurried to their homes before dark. Now everything has changed. Sometimes people...
State estimator is vital for on-line power system monitoring, analysis and control. With the increasing use of synchronized phasor measurement units (PMU) in power grids, how to utilize phasor measurements to improve the precision of state estimator becomes imperative. In this paper, a state estimator including voltage phasors, injected current phasors and traditional measurements is proposed. 14...
Load profile is well-known on a LV distribution feeder. However charging of electric vehicles will have a yet unforeseen impact on the system which must be dealt with. The appearance and wide penetration of this new load-type may cause problems on the distribution as well as on the transmission system. DSOs will have to deal with overloading protection and also power quality issues. The paper gives...
Calculations of reliability level for some typical HV switchgear schemes is performed in the paper. Calculations of reliability parameters were performed taking into account unscheduled faults of elements of switchgears and also scheduled maintenance works. In the work there are defined substations with typical load (Typical Substations). The definition of typical substations was based on analysis...
This paper aims to determine how photovoltaic cells are affected by depositions and shadow casting on their surface. Shadow casting effect on the photovoltaic panels is easily discernible, especially when it is permanent. The appearance of a shadow caused by a tree or a chimney, for example, reduces the amount of energy produced. Depositions, such as snow, dust and dirt that may also appear on the...
The implementation of energy smart grids encompasses local area energy distribution to a fine grained network of locations. For many years, at this level of last mile energy consumption, smart grid management is an inexistent concept, because little (or none at all) feedback is given from final consumer installations to utility infrastructure. Traditionally because installed energy meters where purely...
This paper is the second one in a series of two papers presenting the main results obtained, which are analyzed in view of the present RSECE Portuguese national regulation.
The study deals with the issue of nuclear energy in power engineering of Slovakia in the future. It comes out from the present situation of power engineering and highlights the fact that the installed capacity of Slovakia will decrease due to the lifetime of production equipment. In order to ensure sustainable energy supply it will be necessary to compensate the outage of production with new, mainly...
This paper is the first one in a series of two papers presenting the main results obtained in a School Building, which are analyzed in view of the actual Indoor Air Quality (IAQ) Portuguese national regulation. Measurements were carried out in one building, ventilated by mechanical system to evaluate IAQ and thermal comfort parameters. Direct measurements were made with portable monitoring data loggers...
Load forecasting is important for power systems planning, and, on the operational level, for the grid operators and the balance responsible parties. A decrease in the load forecasting error increases the security of supply, and leads to the decrease in the financial costs for both market participants and the power system as a whole. Different studies have investigated influence of load forecasting...
Today's growing energy market and demand for renewable energies has generated an increasing request for advanced transmission technologies. The transmission systems must be able to handle demanding conditions, such as long distance water crossing, but still have low power losses. During the last decade the HVDC Light® has proven to be a preferable solution for such applications, in particular for...
The importance of photovoltaic cell/module as a continuous operating system is a well-known necessity. Reliable predictive and preventive maintenance techniques are needed to assure lifetime efficiency in service. For this we need to know what kind of defects can occur, the most probable frequency and where it can appear. The current paper investigates a nondestructive method based on infrared (IR)...
In the wake of growing concerns over petroleum supplies and air pollution, hybrid electric vehicles are being developed as safe alternatives to conventional engine vehicles. While the representativeness of standard driving cycles may be questioned, the vehicle electrification brings up new design issues in terms of power rating for energy savings purposes. The present paper aims at proposing a methodological...
The application of the brushless doubly-fed machine (BDFM) is in wind power generation in harsh conditions, where reliability is important. In this paper, eddy current losses in a BDFM in four categories: a) the rotor classic eddy current losses, b) stator classic eddy current losses, c) rotor excessive eddy current losses, and d) stator excessive eddy current losses, are calculated for single frequency...
Jules Horowitz Reactor (JHR) is an international project aimed on the construction of new high-performance nuclear reactor for research on materials and nuclear fuel (Material Testing Reactor, MTR). The Czech Republic - based Research Centre Rez Ltd. is responsible for the development and delivery of the hot cells prototype. Hot cells are used for handling of nuclear fuel and irradiated materials...
The paper intends to give a contribution to the investigation, by both computer simulations and laboratory tests, on the criteria for the selection of the SPD protection level (Up) in order to limit the voltage at the equipment input to a value less than or equal to its withstand voltage (Uw). Such criteria are strongly influenced by installation conditions of SPD (i.e. length of the leads connecting...
This paper reviews the biomass and lignite cofiring project in a lignite fired Power Plant in Hungary. It is based on the referred BSc Thesis [4], in which it has been examined the behaviour of a single unit in a lignite fired power plant in case of different biomass/lignite mixture ratio. The object of the examination was to show how the basic features of the combustion change, especially the heat...
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