The implementation of micro scale combined heat and power systems is one of the ways to improve the energy security of consumers. In fact, there are many available large and medium scale cogeneration units, which operate according to the Rankine Cycle. Due to European Union demands in the field of using renewable energy sources and increasing energy efficiency result in the importance of additionally developing systems dedicated for use in residential buildings, farms, schools and other facilities. This paper shows the concept of introducing thermoelectric generators into typical wood stoves: steel plate wood stoves and accumulative wood stoves. Electricity generated in thermoelectric generators (there were studies on both three market available units and a prototypical unit developed by the authors) may be firstly consumed by the system (to power controller, actuators, fans, pumps, etc.). Additional power (if available) may be stored in batteries and then used to power home appliances (light, small electronics and others). It should be noted that commercially available thermoelectric generators are not matched for domestic heating devices – the main problems are connected with an insufficient heat flux transmitted from the stove to the hot side of the generator (caused e.g. by the non -homogeneous temperature distribution of the surface and bad contact between the stove and the generator) and inefficient cooling. To ensure the high efficiency of micro cogeneration systems, developing a dedicated construction both of the generator and the heat source is necessary.
The paper presents the method for multicriteria design of a synchronous generator voltage regulator. The results of the voltage regulator polyoptimisation are compromise sets for a classic controller of type PI and fuzzy logic controller of type Takagi-Sugeno-Kang. A genetic algorithm is used to solve the polyoptimisation problem.
This paper presents an analytical model of a three-phase axial flux coreless generator excited by permanent magnets, with special focus on determining the model pa- rameters. An important aspect of this model is the derivation of a coefficient that corrects the flux on the inside and outside edges of the magnets. The obtained parameters are ver- ified by performing field analyses and measurements. A comparison of the results show satisfactory convergence, which confirms the accuracy of the proposed analytical model.
The paper discusses in detail the construction of the Core Less Axial Flux Permanent Magnet generator simulation model. The model has been prepared in such a way that full compatibility with the elements of the SimPowerSystem library of the Matlab/Simulink package is preserved, which allows easy use of the presented simulation model for testing the work of the generator as part of a larger system. The parameters used in the model come from the MES 3D calculations performed in the Ansys/Maxwell software, for a machine prototype with a rated power of 2.8 kW, which was then used to experimentally verify the correct operation of the presented model of machine.
An analysis of the power system functioning and the behaviors of the energy market participants allows the trends taking place within years to be identified, including these associated with the evolution of the electric energy and power demand profiles. The problems of balancing the peak power demand are of both a short and long term nature, which implies the need for changes in the electricity generation sector. Apart from the existing “silo-type” generation units, the construction of distributed energy sources implemented in the civic formula in the framework of self-sufficient energy communes and energy clusters is becoming increasingly important. Support for these programs is realized both at the legislative level, as well as within dedicated competitions and ministerial activities. The financial support carried out by the National Fund for Environmental Protection and Water Management and the Regional Operational Programs is also noticeable. One of the activities aimed at spreading the idea of clustering was the competition for certified energy clusters, conducted by the Ministry of Energy. The goal of the contest was the promotion and development of the distributed energy sector, which could be used for the improvement of energy security in the local manner and constitute a basis for the knowledge necessary in planning and developing the state’s energy policy. The paper presents a synthetic analysis of the results of the competition for a certified energy cluster from the perspective of planning and operational needs related to the functioning of the power system. Further, the information about the investment plans of new generation capacities, including their breakdown with respect to type, achievable power and costs has been provided. Also, the balancing of the demand for electric energy by own generation within the energy clusters has been characterized for three time perspectives
Electric cars (SE) are currently considered to be one of the best ways to reduce CO2 and other air emissions in the transport sector as well as noise in cities. They can reduce the dependency of road transport on imported oil in a visible way. Nevertheless, the demand for electricity for a large amount of SE in road transport is not insignificant and has an impact on the power system. The article analyzes the potential impact of SE on the demand, supply, structure and costs of electricity generation as well as emissions as a result of introducing 1 million SEs by 2025 on Polish roads, and tripling this number by 2035. The competitive electricity market model ORCED was used for the calculations. The results of the analysis indicate that regardless of the charging strategy, the demand for SEs causes a slight increase in the overall electricity demand in Poland and consequently also a slight increase in power generating costs. Even a large increase in SEs in road transport will result in a rather moderate demand for additional generation capacity, assuming that power companies will have some control over the mode of charging cars. The introduction of SEs will not reduce CO2 emissions compared to conventional cars in 2025, on the contrary will increase them regardless of the loading strategy. In 2035 however, the result depends on the charging scenario and both the increase or decrease of emissions is possible. Electric vehicles will increase SO2 net emissions, but they will contribute to a decrease in the net emissions of particulates and NOx.
The article concerns safety of power supply for the final consumers, especially its two comprising elements, which are generation adequacy and distribution system reliability. Generation adequacy has been defined with Loss of Load Probability (LOLP), Loss of Load Expectation (LOLE) and Energy Not Supplied (ENS) indices. Conclusions from generation adequacy forecast prepared by ENSTO-E for Poland compared with other European countries for the years 2020 and 2025 have been discussed along with the resulting threats. Interruptions in energy supply have been characterised by power discontinuity indicator SAIDI. Finally, a reliability and adequacy analysis have been performed for different scenarios of the Polish power system operation in order to assess possibilities of using distributed generation as a backup power source. Based on a simulation model created using the DIgSILENT Power Factory software, the reliability and adequacy calculations have been performed with the probabilistic non-sequential Monte Carlo method and they are followed by a discussion of the obtained results.
This paper shall present and explain the key aspects related to the issue of combined heat and power generation (CHP – Combined Heat and Power or Cogeneration). The cooperation with the water treatment plant launched allowed a closer look at the described technology as well as allowed the analyses and survey. The survey on the efficacy of the selected components of the cogeneration system was based on two cogeneration units fuelled with biogas produced in the sewage fermentation.
The paper is an exploration of the optimal design parameters of a space-constrained electromagnetic vibration-based generator. An electromagnetic energy harvester is composed of a coiled polyoxymethylen circular shell, a cylindrical NdFeB magnet, and a pair of helical springs. The magnet is vertically confined between the helical springs that serve as a vibrator. The electrical power connected to the coil is actuated when the energy harvester is vibrated by an external force causing the vibrator to periodically move through the coil. The primary factors of the electrical power generated from the energy harvester include a magnet, a spring, a coil, an excited frequency, an excited amplitude, and a design space. In order to obtain maximal electrical power during the excitation period, it is necessary to set the system’s natural frequency equal to the external forcing frequency. There are ten design factors of the energy harvester including the magnet diameter (Dm), the magnet height (Hm), the system damping ratio (ζsys), the spring diameter (Ds), the diameter of the spring wire (ds), the spring length (ℓs), the pitch of the spring (ps), the spring’s number of revolutions (Ns), the coil diameter (Dc), the diameter of the coil wire (dc), and the coil’s number of revolutions (Nc). Because of the mutual effects of the above factors, searching for the appropriate design parameters within a constrained space is complicated. Concerning their geometric allocation, the above ten design parameters are reduced to four (Dm, Hm, ζsys, and Nc). In order to search for optimal electrical power, the objective function of the electrical power is maximized by adjusting the four design parameters (Dm, Hm, ζsys, and Nc) via the simulated annealing method. Consequently, the optimal design parameters of Dm, Hm, ζsys, and Nc that produce maximum electrical power for an electromagnetic energy harvester are found.
This paper provides some information about thermoelectric technology. Some new materials with improved figures of merit are presented. These materials in Peltier modules make it possible to generate electric current thanks to a temperature difference. The paper indicates possible applications of thermoelectric modules as interesting tools for using various waste heat sources. Some zero-dimensional equations describing the conditions of electric power generation are given. Also, operating parameters of Peltier modules, such as voltage and electric current, are analyzed. The paper shows chosen characteristics of power generation parameters. Then, an experimental stand for ongoing research and experimental measurements are described. The authors consider the resistance of a receiver placed in the electric circuit with thermoelectric elements. Finally, both the analysis of experimental results and conclusions drawn from theoretical findings are presented. Voltage generation of about 1.5 to 2.5 V for the temperature difference from 65 to 85 K was observed when a bismuth telluride thermoelectric couple (traditionally used in cooling technology) was used.
A steam generator in a nuclear power plant with a light water reactor is a heat exchanger, in which the heat is being transferred from the primary to the secondary loop (it links the primary and secondary loops). When the power plant is running, the inlet parameters (temperatures and mass flow rates) on both sides of the steam generator can change. It is important to know how the changes of these parameters affect the steam generator performance. The complexity of the processes taking place in the steam generator makes it difficult to create a simulator reflecting its performance under changed conditions. In order to simplify the task, the steam generator was considered as a ‘black box’ with the aim of examining how the changes of the inlet parameters affect the changes of the outlet ones. On the basis of the system (steam generator) response, a simple mathematical model of the steam generator under variable load conditions was proposed. In the proposed model, there are two dimensionless parameters and three constant coefficients. A linear relation between these dimensionless parameters was obtained. The correctness of the model was verified against the data obtained with a steam generator simulator for European Pressured Reactor and AP-600 reactors. A good agreement between the proposed model and the simulator data was achieved.
This paper presents the main dilemma of development of the Polish energy sector on the 20th anniversary of the first liberalization directive of the European Union, which created the energy market. The situation in the Polish energy sector based on fossil fuels, its transformation into lower emission one is closely connected to the process of restructuring and further development of the mining sector. On the other hand, we are witnessing the development of RES, household installations producing electricity with storage and the electrification of public transport. The investments in new, large scale fossil fuel fired power plants are very expensive and not economically proven when electricity prices are low. Until the new direction of investment in energy sector will be decided, the option of the lasting of the operating existing power units seems to be a good proposal. Is the thesis: “The energy security of Poland should be fully based on indigenous sources, generation and distribution assets, delivering electricity to end users. Ensuring competitive energy prices to the economy and households, the market should be fully open to producers and consumers, including chip electricity arising from the European single market” the right assumption for the Polish energy policy?
The article analyzes the names given today to the children of inhabitants of Przemyśl — followers of Catholicism and Orthodoxy, at the same time showing their differences and similarities within both religions. In the same urban, communication and cultural community, Catholic and Orthodox live side by side (often for many generations). Despite everything, they to some extent retain their own identity (culture, traditions and customs), which also manifests itself in the names given to children. For a more complete picture of the situation, the names of the two older generations (parents and grandparents) were also presented.
The article discusses the importance of small hydro power plants in the Polish power system and defines the legal conditions for the operation of small hydro power plants. The phenomena occurring in the hydrological system of small hydro power plants and their impact on the natural environment were analyzed. An analysis of phenomena occurring in the hydrological system and the activity of small hydro power plants that are operating on the Radunia River helped us identify relations between different types of power plants working in cascades and possibilities of power generation control in period of several days. The above-mentioned analysis has been used in the development of a mathematical model of a hydroelectric plant and cascades of hydroelectric plants. The numerical simulations carried out concerned both the self-operating power plant and a cascade of two identical objects of this type. There is a possibility for small hydro power plant to run as a base load power plant and during periods of high demand as well (peak demand or unexpected loss of generation in the power system). A single hydroelectric power plant can deal with varying peak load demands while adding a second stage increase those abilities. A cascade of reservoir hydropower plants has a much greater ability to store energy and give it back in time. In addition, the existence of a second power plant equipped with a surge reservoir allows for a significant reduction in the amplitude of flows in the river below the cascade, which will reduce the negative impact of the cascade on the environment.
The transition of power grids to implement large amounts of nonsynchronous renewables reduces the inertia in the power system. Therefore, the rate of change of frequency (ROCOF) after a fault of given energy is higher in low inertia grids than in grids with mainly synchronous machines operating. Standard faults for the design of existing synchronous machines assume fixed frequency grids, in which an electrically close fault happens. It is not tested, if the machines can ride through transient disturbances with high ROCOF. For ROCOF values of up to 1 Hz/s as foreseen for the upcoming grid code of the Republic of Ireland and up to 2 Hz/s for Northern Ireland, a thorough verification, if generators are capable to ride through such events is necessary. For this study, ROCOF frequency traces provided by the transmission system operators (TSOs) of Ireland were first benchmarked with a full-grid model and in a second step impressed on a model of generators connected to the power grid via a step-up transformer to study transient stability and nonlinear response of the generator. This paper focusses on the ability of nine different synchronous machines to stay connected to the transmission system during severe ROCOF events without losing synchronism.
We present a new hash function based on irregularly decimated chaotic map, in this article. The hash algorithm called SHAH is based on two Tinkerbell maps filtered with irregular decimation rule. We evaluated the novel function using distribution analysis, sensitivity analysis, static analysis of diffusion, static analysis of confusion, and collision analysis. The experimental data show that SHAH satisfied valuable level of computer security.
A new time interval/frequency generator with a jitter below 5 ps is described. The time interval generation mechanism is based on a phase shifting method with the use of a precise DDS synthesizer. The output pulses are produced in a Spartan-6 FPGA device, manufactured by Xilinx in 45 nm CMOS technology. Thorough tests of the phase shifting in a selected synthesizer are performed. The time interval resolution as low as 0.3 ps is achieved. However, the final resolution is limited to 500 ps to maximize precision. The designed device can be used as a source of high precision reference time intervals or a highly stable square wave signal of frequency up to 50 MHz.
The paper presents an induction generator connected to the power grid using the AC/DC/AC converter and LCL coupling filter. In the converter, both from the generator and the power grid side, three-level inverters were used. The algorithm realizing pulse width modulation (PWM) in inverters has been simplified to the maximum. Control of the induction generator was based on the indirect field oriented control (IFOC) method. At the same time, voltage control has been used for this solution. The MPPT algorithm has been extended to the variable pitch range of the wind turbine blades. The active voltage balancing circuit has been used in the inverter DC voltage circuit. Synchronization of control from the power grid side is ensured by the use of a PLL loop with the system of preliminary suppression of undesired harmonics (CDSC).
This paper presents the possibility of reducing the demand for nonrenewable primary energy for buildings using a new conceptual adsorption system of cooling and heating supplied by solar energy. Moreover, the aim of this study is to shorten the payback time of investment in the standard adsorption cooling system through its integration with the heating system. Research has been carried out for an energy-efficient medium-sized single-family building with a floor area of 140 m2 and a heat load of 4.2 kW and cold load of 4.41 kW. It has been shown that the use of an adsorption system of cooling and heating supplied by solar energy decreased the demand for nonrenewable primary energy by about 66% compared to the standard building that meets the current requirements.
Energy efficiency improvement and ecological safety of heat power plants are urgent problems, which require scientifically grounded approaches and solutions. These problems can be solved partly within the presented heat-and-power cycles by including contact energy exchange equipment in the circuits of existing installations. A significant positive effectis obtained in the contact energy exchange installations, such as gas-steam installation ‘Aquarius’ and the contact hydrogen heat generator that also can use hydrogen as a fuel. In these plants, the efficiency increases approximately by 10–12% in comparison with traditional installations, and the concentration of toxic substances, such as nitrogen oxides and carbon monoxide in flue gas can be reduced to 30 mg/m3and to 5 mg/m3, respectively. Moreover, the plants additionally ‘generate’ the clean water, which can be used for technical purposes.
The uncontrolled rectifier and controlled rectifier which use fixed switching frequency control strategy are applied usually during the working of a high-power high- speed permanent magnet generator (HSPMG). Even for the controlled rectifier, it will generate harmonics. The electromagnetic performance of the HSPMG is also affected by these harmonics. In this paper, the influences of the fixed switching frequency control strategy on a HSPMG were studied. Based on the Fourier theory, the harmonic currents of the generator were analyzed, and the change of harmonic distribution range and current total harmonic distortion (THD) were obtained. By using an indirect field-circuit coupling method, the influences of the fixed switching frequency control strategy on the losses and torque of the generator were analyzed. The relations between the switching frequency and the losses and torque of the generator were obtained, and the change mechanism of the loss was revealed. The obtained conclusions can provide reference for the optimized choice of the switching frequency of the distributed generation system with the HSPMG. It can also provide support for the HSPMG electromagnetic structural optimization and the optimization of the loss and harmonic on the system level.
This article analyzes the common Slavic linguistic atlas maps (OLA). Assessing the preliminary results of the OLA project, the author focused her attention on the new linguistic geography data given in the Atlas, and the evolution of some units and Proto-Slavic dialect differentiation of Slavia.
This paper presents a concept of humanoid robot motion generation using the dedicated simplified dynamic model of the robot (Extended Cart-Table model). Humanoid robot gait with equal steps length is considered. Motion pattern is obtained here with use of Preview Control method. Motion trajectories are first obtained in simulations (off-line) and then they are verified on a test-bed. Tests performed using the real robot confirmed the correctness of the method. Robot completed a set of steps without losing its balance.