Piotr Biczel

Design of power plant capacity in DC hybrid system and microgrid

– 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 systems capacity and power and optimize them. The authors have not found similar methods in the literature.

Simulink Models of Power Electronic Converters for DC Microgrid Simulation

In the time of rapid changes in power industry the need to develop new power systems arises. The newly developed systems should aim at wide utilisation of renewable power sources and CO2-neutral technologies. This goal can be achieved by e.g. dissipated generation, or integrating DG into microgrids. The microgrids can be built using AC or DC current networks. Authors propose DC microgrid as a new idea for a small, balanced distribution power system. It has been designed to supply small towns and villages with electricity with high penetration of renewable energy resources. However, designing an optimal microgrid is not an easy task, due to the fact that primary energy carriers are changeable and uncontrollable, as is the demand. Traditional design and optimisation tools, developed for controlled power sources, cannot be employed here. Simulation methods seem to be the best solution. The microgrid consists of several devices, with most important among them - the power electronic devices.

Hybrid photovoltaic-fuel cell power plant

Nowadays, in many countries the increase of generating capacity takes place in small units of so-called distributed power industry (distributed generation). In the paper are presented: the experiences from exploitation of hybrid solar- wind power plant; concept of solar power plant with fuel cell. This last solution enables optimal utilization of primary energy sources and increases the level of supply reliability. Authors have worked for several years on stand alone hybrid solar-wind power plant for supply of telecommunication equipment. The main problem in such installations is how to guarantee power supply all year without interruptions. Weather conditions in Poland provide to breaks in winter and autumn. The paper shows proposal of a new power plant with fuel cell and solar panels. The idea is to generate energy from PV panels as long as it is possible. When there is no Sun energy will be produced by fuel cell. Because of the system will operate rather far from service centers it has to work as long as it is possible without refueling. Power summation and control algorithm is explained, power electronics converters and control system are described.

Energy Storage Systems

There is no doubt the near future will drive power generation towards DG and RES. Distributed generation units are not controlled and regulated by the power system operators. The power produced in DG units is optimized by the owner in order to maximize the profit, heat production or renewable sources utilization. This is done regardless of the power demand in the networks to which the sources are connected. If the DG utilization reaches more then dozen or so percent of the power production, the problem of power balancing will occur either in the local grid or in the whole system. The problem will become even bigger, if, as EU officially recommends, the power generation is based mainly on renewable sources, such as wind turbines or solar energy. Employment of renewable sources will cause not only decrease in the power quality, but also complications in balancing the power system.

The control strategy for a Solid Oxide Fuel Cell Hybrid System

Based on mathematical modeling and numerical simulations, the control strategy for a Solid Oxide Fuel Cell Hybrid System (SOFC-HS) is presented. Adequate maps of performances with three independent parameters are shown. The independent parameters are as follows: stack current, fuel mass flow and turbine-compressor shaft speed. Those parameters can be controlled by external load, fuel valve and turbine-compressor shaft speed, respectively. The control system is purposed to meet many constraints: e.g. stack temperature, steam-to-carbon ratio, compressor surge limitation etc. The aim is to achieve maximum efficiency of power generated within those constraints. Governing equations of SOFC-HS modeling are given. An adequate simulator for the SOFC module was produced and described. Based on this simulator, the control strategy was obtained. The performance of this SOFC-HS is shown in various working environments.

Future perspectives of energy sector and energy market in EU

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 Control Strategy for a Solid Oxide Fuel Cell Hybrid System

Based on mathematical modeling and numerical simulations, the control strategy for a Solid Oxide Fuel Cell Hybrid System (SOFC-HS) is presented. Adequate maps of performances with three independent parameters are shown. The independent parameters are as follows: stack current, fuel mass flow and turbine-compressor shaft speed. Those parameters can be controlled by external load, fuel valve and turbine-compressor shaft speed, respectively. The control system is purposed to meet many constraints: e.g. stack temperature, steam-to-carbon ratio, compressor surge limitation etc. The aim is to achieve maximum efficiency of power generated within those constraints. Governing equations of SOFC-HS modeling are given. An adequate simulator for the SOFC module was produced and described. Based on this simulator, the control strategy was obtained. The performance of this SOFC-HS is shown in various working environments.

Power Electronic Devices in Modern Power Systems

There are two main trends in present development of power systems. First is a wide utilization of renewable power resources. The second is decentralization of power generation. Hence, small power sources, very often RES sources, called dissipated power generators are developed. They are usually in range of megawatts starting form kilowatts. They operate automatically and are remotely controlled. In fact the sources are electronic devices. Microprocessor control units are used to control power production and perform remote control and power electronic converters are used to control power flow. So, many different kinds of power electronic devices are required. Another political and social trend is local balancing of power production and power consumption. It means that all power consumed in some are should be generated in the area. Hence small power systems are developed called microgrids. Microgrids consist of power sources, loads, control units and lines, like normal public grid. But the microgrid is limited to the small area, i.e. village, town, and automatically controlled. Again power electronic devices and control units decide about the microgrid performances. Development of required devices, both power electronic and controllers, are possible only with close cooperation of research units, like Warsaw University of Technology, and production firms, like APS Energia. APS Energia offers many power electronic converters and complete power plant and control and supervisory remote controllers for power industry. Some are especially developed for dissipated generation. The Universitys researchers design some devices and their principles of operation. APS Energia produces the devices. The main, presented in the paper are inverter with MPP tracking for PV systems, inverters for supplying AC loads from DC power systems, PEM fuel cell power generation units, battery chargers, high power inverters and rectifiers with sinusoidal input current, synchronization systems and remote control and monitoring devices. There are some examples of applications in the paper.