Henryk MAJCHRZAK, Grzegorz TOMASIK, Mieczysław KWIATKOWSKI
Application of energy storage technology for integration of wind farms with an electric power system
The development of energy storage technologies results in a fact that they become one of interesting options supporting harmonic integration of a big amount of renewable energy sources, including wind farms, with an electric power system. Wider development of energy storage technologies application in the frames of wind farms integration with an electric power system is conditioned by technological development in the range of solutions applied in energy storage installations, further improvement of their operating parameters and reduction of unitary investment costs. Additional condition of this development is implementation of legal solutions enabling operation of such installations. Especially important is creation of a possibility for subjects managing the energy storage installations to arise as separate subjects in the energy market as well as elaboration of the mechanism of storing ability allocation. From the transmission system operator point of view concerning maintaining work safety of the national power system it is advisable to secure the operator the possibility of an access to/possession of energy storage resources as one of the instruments enabling integration of a big amount of wind farms with an electric power system.
Keywords: electric power system, wind farms, energy storage
Wind energy in power system case study: Denmark
Denmark produces electric energy in its wind farms in record-breaking proportions. During windy days Danish electric power system makes efforts to export energy to its neighbouring countries while on the windless ones imports it from Scandinavian hydroenergy sources. This practice is defined as electric energy storage for softening the results of wind power generation discontinuity. Cost resulting from variability of wind energy production equals 4-8% of its market value.
Keywords: electric energy system, wind power industry, balancing, Denmark’s experience in energy production
Adam GUBAŃSKI, Przemysław JANIK, Paweł KOSTYŁA, Jacek REZMER, Tomasz SIKORSKI, Jarosław SZYMAŃDA, Zbigniew WACŁAWEK
Comparative analysis of functionality of power quality monitoring distributed systems
A review is made of technical and functional solutions offered in the area of power quality monitoring systems (PQMS). As opposed to the wide market of mobile devices for power quality recording destined mainly for casual measurements, the attention here is focused on solutions dedicated for distributed synchronous systems with remote access to measurement data coming from a multipoint monitoring of the operational area. One of the tasks set by the authors is defining the PQMS general structure and specifying technical and functional requirements of such system, subsequently helping to compare the available solutions offered in the market. Additionally, the need for data standardization and integration of various devices and subsystems has been mentioned.
Keywords: power quality monitoring, dedicated distributed systems
Digital determination method of the most advantageous distance between discharge electrodes in the ESP chamber
Presented is the method of digital analysis of electrical field distribution in an ESP chamber that enables determination of the most advantageous distance betwee discharge electrodes. The method is based on determination of areas where effectiveness of dust particles electrization is small and on determination of the electric field strength maximum values in an ESP chamber. This method of analysis has been verified by measurements in the corresponding physical model and the obtained results are fully compatible.
Keywords: electrostatic precipitators, discharge electrodes, optimization of the distance between electrodes
Research on partial discharges in a mineral oil and a synthetic ester
Presented are results of comparative measurements of partial discharges in mineral oil and synthetic ester. Measured were inception and extinction voltages of the sliding type partial discharges developing on the surface of a solid insulation material immersed in oil.
Keywords: power transformers, mineral oils, synthetic oils, partial discharges
Temperature influence on dielectric response of a RIP type bushing
Presented are results of FDS insulation measurements of two RIP type bushings. The insulation temperature rise results in tgδ characteristics shifting towards higher frequencies and this effect is proportional to the temperature. Simulation of actual working conditions causes occurrence of a temperature gradient inside the insulation that during the temperature rise influences an uneven tgδ characteristics shift towards higher frequencies. Significant temperature rises in a bushing core result in small temperature changes on a porcelain cover surface.
Keywords: power transformers, bushing insulation, thermal degradation
Simulation analysis of a lightning current distribution in a building lightning protection system (LPS)
Described is a numerical model of a typical external lightning protection system. The model was elaborated to obtain information about lightning current distribution as an effect of a direct lightning strike to this system. To realize this task a MATLAB/SIMULINK environment with the SimPowerSystem library were chosen. Using this tool, a numerical model of a real object with LPS was created and, as a result of a simulation, the results in the form of the current value in every conductor of the LPS structure were obtained. As the next step of this investigation, a simulation of the magnetic field strength distribution inside such a structure was made – to do this, the author created a script program written in the MATLAB environment.
Keywords: building objects, lightning protection systems, lightning current distribution
Marek SZADKOWSKI, Krzysztof MAŹNIEWSKI
Analysis method of statistics images of partial discharges various forms
Presented is a proposal to use a new interpretation method of partial discharges (PD) measurement results. Analyzing linear dependencies between coefficients describing statistical PD phase and amplitude distributions, the authors try to show differences and similarities between „statistics images” of corona, surface and internal discharges. Presented material is an information that the research on new interpretation methods of results obtained by classical measurement methods has begun. Described results are mostly of qualitative character and it was decided to present them in such a way to show a possible big amount of relationships in a relatively small article.
Keywords: insulation systems, diagnozing, partial discharges
Shock voltage measurements with the use of a high voltage surge generator insulated from the ground
Presented are measurement results of shock voltages (touch and step ones) occurring in the immediate neighbourhood of a production hall during the surge current flow. The source of surge current was a high voltage generator insulated from the ground. Its unique construction enabled
generation of a 4,7 kA-8/20 μs surge current with nominal capacitors voltage level equal 52 kV – insulation from the ground enabled avoiding the galavanic coupling between charging circuit and the supply line. Thank to this solution no superposition of reflected signals on output current waveform was observed, but during measurements the sparkovers in the ground occurred.
Keywords: step voltage, touch voltage, HV surge current generator, production hall
January L. MIKULSKI
Research problems concerning implementation of live works on national 110 kV (and more) networks
Presented is the research range of problems connected with live line working on 110 (and more) kV networks. It comprises electrical tests of insulating sticks, conductive clothes and aerial lift devices with insulating arms. Discussed is also the procedure of acquainting the linemen with this type of works.
Keywords: live line working, 110 kV networks, linemen training
Information systems supporting generation of heat and electric energy in industrial and commercial CHP plants
Discussed are problems connected with tasks assigned to information systems supporting generation of heat and electric energy in industrial and commercial CHP plants. In particular, metodology of determining and reporting factors characterizing CHP operation as well as determining deflections enabling evaluation of technical condition and the level of equipment operation is presented. Moreover, mentioned are problems connected with optimization of loads distribution with the aim to maximize combined electric energy production and/or production costs optimization as well as problems concerning planning of the municipal heat and electric energy generation.
Keywords: industrial and commercial CHP plants, heat and electric energy generation, information systems
Co-combustion of biomass and coal – its influence on efficiency of the main power unit elements
Mentioned are problems connected with the influence of biomass addition to coal on the change of working conditions and efficiency of a boiler, TG set and the whole power unit. In this analysis, an advantage of measurement results obtained from various objects by Energopomiar was taken, mainly the measurement results of some selected boilers (fluidized bed, dust and stoker-fired ones). The determined efficiency values of these boilers during co-combustion of biomass and coal and during combustion of coal only varied dependently on boiler type and combusted biomass. With the aim to estimate the TG set efficiency, an attempt is made to analyse differences in parameters of a circulation agent in the water steam system occurring during the co-combustion of biomass and coal and the combustion of coal only.
Keywords: power unit, biomass and coal co-combustion
Analysis of possiblity to reduce technical minimum of steam boilers on the basis of the carried out investigations
Presented are basic problems connected with reduction of steam boilers technical minimum with the aim to adapt their capacity to the reduced demand from a heating system. In the analysis of the possibility to reduce the hitherto existing boiler technical minimum, the following conditions are considered: maintaining of the work safety of the pressure part, stability of combustion in the combustion chamber and of the essential boiler operation parameters, and also adaptation of control range of auxiliaries and cooperating installations. All these problems are discussed on the examples of selected research and analyses results carried out by Energopomiar, especially for OP-140, OP-230 and OP-430 boilers as well as for a boiler cooperating with the flue gas desulphurization installation.
Keywords: steam boilers, reduction of technical minimum, research and analyses results