The paper presents the problems of operating a fast charging station for electric vehicles in a collecting point of electric vehicle (EV) car sharing innogyGO! Authors presented measurements of the parameters of the power quality in operational conditions, and also proposed a number of tests that should be carried out to investigate the impact of EV charging on the distribution grid. Each of the analysed tests is a reflection of the real demand for charging vehicles by the end-users.

This paper presents issues related to the connection of new charging points for electric buses, challenges faced by distribution system operators, as well as the impact of electric bus charging systems on the power system in the context of increased demand for electric energy and energy quality.

Modern society relies on the constant flow of quality electricity. Various safety measures in the form of uninterruptible power supplies (UPS) combined with diesel generation systems are used to ensure permanent power delivery to strategic services during a power outage. Batteries UPS systems are held in buffer mode to avoid the self discharge process progressing. The impact of various buffer battery maintenance regimes is an important factor in ensuring the reliability of UPS systems. A series of tests on five battery pairs were performed to estimate the impact of five different buffer regimes on the batteries' state of health. The tests were carried out in the span of one year, at heightened temperature to accelerate the negative impact of the said regimes on the batteries' state of health. The test results showed that, contrary to widely-accepted belief, rippling of the buffer charging current does not have a significant negative impact on battery health. A comparison did indeed show that rippled charging current delivered lower total capacity loss than unrippled current. Then desulfation was applied to the batteries after testing to estimate the amount of capacity that was lost due to sulfation. It determined that rippling promotes more irreversible capacity loss (not caused by sulfation) than unrippled current with the same average voltage. The insights gained from these tests could inform attempts by industry to slow down the deterioration of lead-acid batteries in UPS applications.

Electric buses are now seen as the primary means of public transport in cities. However, their exploitation is associated with a number of limitations. The article presents the problem of battery use in buses. The design differences between the vehicle with the internal combustion engine and the electric motor are discussed. In particular, authors compared the number of passengers that both types of buses can take, as well as the difference in vehicle mass and range, and the reasons for these differences. The types of electrochemical cells that can be used to power vehicles and their basic features are presented. The article focuses on the NMC, LFP, LTO and LIC type cells. Next, the battery pack structure and its components were described. The specific energies of cells and batteries constructed from these cells were compared. Next, the most important features of the vehicle equipped with batteries with various types of cells are discussed. The mass, range, charging time and cycle lifetime of the batteries were compared. The basic dependence was noted: the greater the specific energy, the smaller the number of battery cycles. So if the bus has to take more passengers, it must have light batteries, which should be frequently charged, which requires high cyclic lifetimes.

A wind turbine emulator is an important hardware to simulate wind energy conversion systems. The emulator hardware is often built by a coupled motor as prime mover and controlled by a variable speed drive to the shaft of an electrical generator. In this work, we propose, design and implement a novel wind turbine emulator by using a squirrel cage induction machine and permanent magnet induction generator. The control of the prime mover is performed by an IGBT AC drive. The drive itself is controlled by a 32-bit microprocessor. Furthermore, the computer supervises the drive and generates the wind patterns and sets the configuration of wind turbine models. This allows the user to define different wind patterns and to emulate different wind turbines. The combination of the PI controller, the computer supervision, and the microprocessor ensures an accurate performance of entire system. The frequency of the generated voltage is proportional to the shaft rotational speed. Therefore, the output voltage frequency is used as a rotational speed meter. RS-485 is the main communication channel between the drive and the computer. Finally, the results demonstrate the effective and accurate performance of the proposed emulator in reproducing the dynamics of an actual wind turbine.

The control system of molten carbonate fuel cell (MCFC) coupled with a gas turbine (GT) should be based on the multilayer structure (two- or three-layers), wherein the third layer is connected with the power output from the system and can be considered separately. Simulation model of the MCFC–GT hybrid system (HS) was built. The simulator is based on a zero-dimensional modeling of the individual elements of the system. The simulator was used for mapping the main components behavior (MCFC and GT separately). On the basis of the obtained maps of the performances and adopted restrictions on technical–operational nature, the operation line for the first line of the control strategy was obtained. The control system which realizes the obtained control strategy was built in reality. Then, the hardware-based models of the main elements were created based on the electric equipment. The hardware–software model was connected to the control system and adequate simulations were performed. The presented results indicate that the analyzed MCFC–GT HS possesses a high operation and control flexibility while at the same time maintaining stable thermal efficiency. Operation of the system is possible over a wide range of parameter changes.

This paper presents research into a resistojet model that can be powered by supercapacitors for satellite propulsion applications. The performance of the system, calculated including a preliminary study of mass and power budget, shows that this solution has potential for a certain range of space missions. The main problem when designing a pulsed resistojet is the compromise between the thermal capacity of the resistojet and the heat transfer efficiency of the device. When the heater is used in pulsed mode, it should have low mass and thermal capacity in order to reduce the energy required to heat the devices. On the other hand, the main technical restriction in resistojet thrusters is heat transfer due to the laminar regime of the flow in the heater. The heat transfer area should be as large as possible, but the mass of the device limits any such increase in area. In this research several design options were considered in an attempt to find the optimal solution. After research on the oscillating element and porous heater, capillary tubes directly heated by the current were determined to be the most effective solution. A power supply based on supercapacitors was constructed. It consists of 30 supercapacitors of 300 F each, connected to deliver 70 V of voltage, 10 F of total capacitance and maximum peak power of 5 kW. Research for three different gases – ammonia, propane and butane – was conducted and the results are presented in this paper.

In this paper a novel approach to accommodate distributed generation resources in the power distribution system is discussed to reduce the peak power demand. Direct load control (DLC) is the capability of aggregate and precisely control individual loads on command. The novel implemented approach in this work is the DLC to demand response. The DLC algorithms in regularity base are used for controllable loads which can be turned on and off with unnoticeable interruption where the load is forecasted and it is dispatched accordingly by using distributed generation resources and controllable loads, thereby it helps to reduce peak demand. Multi-Agent System (MAS) is consisting a group of agents which are capable of perceived environment that they are located and act on it by communicating with each other to achieve the goals. Therefore a MAS has been adopted to manage the direct load control simulation. Load has forecasted in MATLAB and MAS has programmed in ZEUS utilize the forecasted load data to dispatch the load in such a way so as to reduce the peak demand. The agents are located at demand aggregator level, zone level and DG level. They communicate to dispatch the load properly based on resources and load availability. Streszczenie. W niniejszym artykule przeanalizowano nowatorskie podejście do integracji źrodel rozproszonych w celu redukcji szczytow zapotrzebowania na moc. Poprzez precyzyjną kontrole obciązenia i odpowiednie grupowanie odbiorcow mozliwe jest ksztaltowanie zapotrzebowania. Nowatorskie podejście zaprezentowane w artykule polega na ksztaltowaniu reakcji na zapotrzebowanie. Algorytm ksztaltujący podstawe obciązenia jest wykorzystywany do kontroli sterowanych odbiorow, ktore mogą byc wylączane i zalączane bez negatywnego wplywu na ich prace. Obciązenie takie moze byc prognozowane i odpowiednio ksztaltowane co pomaga redukowac szczyt zapotrzebowania. System wieloagentowy (ang. Multi Agent System (MAS)) sklada sie z grup inteligentnych agentow osadzonych w konkretnym środowisku, wspoldzialających z nim i komunikujących sie miedzy sobą, w celu osiągniecia wyznaczonych celow. Taki system zostal zaadaptowany do symulacji zarządzania ksztaltowaniem zapotrzebowania. Obciązenie jest prognozowane w środowisku MABLAB, natomiast MAS zostal wykonany w programie ZEUS w oparciu o prognozy obciązenia, tak by je ksztaltując wygladzic szczyt zapotrzebowania. Agenci są umieszczeni na poziomach agregacji obciązen, stref i generacji rozproszonej. Prawidlowe ksztaltowanie zapotrzebowania odbywa sie w oparciu o dostepne zasoby i źrodla. (Bezpośrednie sterowanie obciązeniem w sieciach inteligentnych - sterownie rozproszone z komunikacją dwukierunkową)

Increasing role of electricity energy in economical development and living level of human societies is unavoidable. Over these recent years the environmental issues such as increase of Pollutants, the global warming, the establishment of strict laws of environmental issues and international protocols like Kyoto in 1997 and Copenhagen in 2009, also economical issues like the fluctuation of the oil and gas prices regarding resources limit and political events have made politicians to be concerned for future energy. Hence, in this paper, current and future energy factors consisting energy generation, consumption, price, environmental, and market issue in European Union (EU) are analyzed and discussed.

The current uncertainty about oil and gas prices and their resources, and future energy concerns, smart grids lead to further development. In this paper, a two way communication-based distributed control for voltage regulation in smart grid is proposed. Moreover, 16-bus distribution feeders system is modeled by real time simulation in MATLAB/Simulink in order to evaluate the effectiveness of the proposed scheme. The results are evidence for capability of proposed system to regulate the voltage in smart distribution feeders.

Trend of reconfiguration of power system is leading to smart grids which are absolutely best possible solution for future power systems. Future smart grids, including Distributed Generation (DG) units, encounter a broad range of challenges like metering, management, and control. In this paper, architecture for fuzzy multi-agent based control for voltage regulation in smart grid is proposed. To investigate the effectiveness of the proposed architecture, a simulation model in MATLAB/Simulink is done. The simulation results show how proposed system can regulate voltage in smart distribution feeders.

Nowadays people should pursue reduction of power consumption. One of the ways to reach that aim is improvement of power transmission and distribution. Power factor increase is the basic way to power losses reduction. Street lighting is a good example of the system which integrates problems of power consumption and distribution. The paper describes concept of powering street lighting with DC voltage line. The estimation of losses decrease and power factor increase is presented. (Power Supply of Street-lighting Using Direct Current)

Power electronic converters are an integral element of power generation systems based on renewable energy sources which is photovoltaic array. Converters enable the control and correction measures of current and voltage characteristics on the output of the power plant, as well as proper operation of energy storage device. Moreover, such converters facilitate and control power load of the power electronic system. Particular interest should be paid to the parameters of the converter responsible for the operation of the energy storage device. It should be characterized by: easiness of control, low costs and especially high efficiency. The authors suggestion for this application is to implement a resonant LCC converter in a three-phase converter system. Research of the device has been conducted in a one-dimensional energy flow version. Tests for resonant system and hard switching have also been done. Conducted tests provide evidence of the converters high efficiency at the voltage level of the rated voltage. The results prove that the mentioned converter is appropriate for application in cooperation with a battery energy storage device. What is more, the dynamic and static characteristics of the investigated converter are also satisfactory. Still, in order to facilitate the formation of new converters prototypes, the authors designed a universal bridge system with a driver. Suggested model enables formation of devices with the power range from hundreds of watts to several dozens of kilowatts.

Technical and economic aspects of construction DC microgrid are presented in the paper. At the beginning the idea of the microgrid, small power system, is shown. Devices, which are necessary for proper operation of the microgrid, are mentioned. Microgrid's similarity to the power system are highlighted. Microgrid may also provide system services for the National Power System (NPS). The importance of modern power electronics converters for interconnection of power sources with DC microgrid and DC microgid with NPS is mentioned. The economic aspects of the described solution are presented. Factors affecting the economic efficiency are described. The topology of the authors' DC microgrid, based on photovoltaic modules, wind turbine, diesel generator set and battery energy storage device, is presented. The main assumption of the design was to fulfill power demand without any energy exchange with NPS. Minimum share of diesel generator set in power generation are assumed as well.

– The purpose of this paper is to present the simulation method of power plants and storage system capacity design., – Owing to solar irradiation, wind speed and water flow are highly and randomly changeable, time variation of the signals needs to be taken into consideration as well as some features of the power plants and storage system. A Matlab/Simulink model of the given system – DC microgrid has been developed. The model allows simulation of a few years static simulations of the power balance. Hence, it can be used to size the plants., – An effective method of the power system design has been developed. It allows sizing the plants taking into consideration resources and load profiles, year changes in profiles and future development of the system. The storage system can be optimized to avoid high power unbalance and power cost increasing., – The model describes only static power behaviour of the modelled power system. It does not allow simulating local voltage changes and dynamic properties of the plants and storage., – This technique helps to size the plants and, first of all, storage system taking into consideration several technical and economical issues., – The method gives opportunity to design a storage system's capacity and power and optimize them. The authors have not found similar methods in the literature.