Showing papers presented at "International Symposium on Environmental Friendly Energies and Applications in 2016"

Biomass gasification technology: The state of the art overview

Abstract: The reduction of imported forms of energy, and the conservation of the limited supply of fossil fuels, depends up on the utilization of all other available fuel energy sources. Biomass is a renewable energy source and represents a valid alternative to fossil fuels. The abundance of biomass ranks it as the third energy resource after oil and coal. Moreover, when compared to fossil fuels, biomass fuels possess negligible sulphur concentrations, produce less ash, and generate far less emissions in to the air. In other words, biomass can deliver significant greenhouse gas reductions in electricity, heat and transport fuel supply. The energy in biomass may be realized by different thermochemical technologies of which gasification is most promising alternative routes to convert biomass to power/heat generation and production of transportation fuels and chemical feedstock. This paper deals with the state of the art biomass gasification technologies, evaluating advantages and disadvantages, the potential use of the syngas and the application of the biomass gasification. Also, this paper provides short overview of the current status of the biomass gasification in Serbia.

Grid-connected PV virtual instrument system (GCPV-VIS) for detecting photovoltaic failure

Abstract: This paper presents a design and development of a Grid-Connected Photo Voltaic Virtual Instrumentation System (GCPV-VIS) which is intended to facilitate monitoring and failure detection of a grid-connected photovoltaic plant using statistical methods. The approach has been validated using an experimental database of environment and electrical parameters from a 1.98 kip plant installed at the University of Huddersfield, United Kingdom. There are few instances of statistical tools being deployed in the analysis of PV measured data. The main focus of this research is, therefore, to devise a Virtual Instrument capable of simulating theoretical performances of PV systems and deploying statistical analysis of PV real-time data. The fault detection is based on the comparison between measured and theoretical output power using t-test statistical analysis. The obtained results indicate that the proposed method can detect the faults of the grid-connected PV system, and can be used for continuous monitoring of PV system status.

Neural network models for electricity prices and loads short and long-term prediction

Abstract: In the framework of competitive electricity market, prices and load forecasting has become a real challenge for engineers in electric power systems. The increase of production from renewable sources increased number of factors that affect the cost and power consumption. On the other side, smart grids and the development of computers enable the use of artificial intelligence for solving such problems. This paper presents the multiple uses artificial neural networks (ANN) in long-term and short-term forecasting electricity prices and loads. Databases that are used for training ANN contain hours and thirty minutes data from British and Serbian power system. Data are related to the production of different energy sources, import / export of energy, temperature and load diagram form. Trained ANNs are used to predict energy prices and the formation of dynamic trifling for Serbia. Formed ANN models can be used for real time, on-line prediction of load and electricity price.

Analysis and distributed control of power flow in DC microgrids to improve system efficiency

Abstract: DC Microgrid attains popularity in integrating renewable energy sources and batteries. It also has the potential to achieve higher efficiency than ac power grid with optimized power flow. In this paper, a general dc microgrid is modeled based on a cluster of general dc nodes, which includes constant power renewables generation, droop-controlled voltage source and different kinds of load. Then the dc power flow is solved for optimization. A voltage restoration method based on consensus algorithm is used to restore the voltage deviation from droop characteristic. An enhanced current regulator is adopted to guarantee the accurate load sharing even under the influence of sensor drift and line resistance. A tie line power flow control method is proposed to regulate the tie line power directly and increase the system efficiency at light load condition. All the considered methods only need the local information and the information from its nearest neighbor thus the system expendability is guaranteed. Simulation and experiment results are provided to validate the proposed methods.

Average value MMC model with accurate blocked state and cell charging/discharging dynamics

Abstract: This paper proposes a simple and accurate average value model (AVM) of a high-power half-bridge MMC for electromagnetic-transient (EMT) studies. Least number of generic EMT blocks is used. Functioning as voltage source converter (VSC), the accuracy of a simplified MMC model would eventually be determined by its accuracy in reproducing the cell charging/discharging dynamics of the detailed models under all operating conditions. The validity of the proposed MMC average value model is verified against a detailed 1GW 21-level model in PSCAD. System dynamics and modelling accuracy of the AVM are tested with various operating conditions, including MMC startup, normal operation with power reversal, DC fault conditions, and MMC cell charging/discharging dynamics from AC and DC sides, with blocked or unblocked MMC status.

Optimal sizing of wind-PV-pumped hydro energy storage systems

Abstract: Storage systems are key components of standalone hybrid renewable energy systems due to intermittent nature of renewable resources. In design of standalone hybrid system, the storage system needs to be optimally sized to guarantee power quality, system reliability and cost effective energy supply. In this paper, the most mature and traditional long term energy storage technology, the pumped hydro energy storage (PHS) is integrated into a standalone wind-PV system. This paper describes the mathematical modelling of a PHS and reports a method for optimal sizing of the wind-PV-PHS systems.

Influence of battery energy storage system on generation adequacy and system stability in hybrid micro grids

Abstract: This paper analyses the influence of Battery Energy Storage System (BESS) on the electrical system in a Hybrid Micro Grid consisting of two 200 kW diesel generators (DGs), one 200 kW wind turbine generator (WTG) and 200 kW photovoltaic (PV) Plant. The BESS in such a system can have a significant role in covering the power fluctuations in the network. The BESS can cover the power unbalance between the supplied power and the load of the grid by storing the excess energy or supplying the residual demand. An advantage of implementing the BESS is faster provision of power compared to the DGs which can also help improve a system stability. In this paper, the influence of BESS is analyzed by conducting Generation Adequacy analysis and Transient Stability studies using DIgSILENT Power Factory software. Generation Adequacy analysis is carried out using Monte Carlo simulation technique. Typical factors such as Loss of Load Probability (LOLP) and Expected Demand Not Supplied (EDNS) are calculated. Furthermore, the size of BESS required to cover for the intermittent nature of renewables is determined. Dynamic models of DGs, WTG, PV and BESS are developed for the purpose of transient stability studies. Contingencies such as three phase fault, tripping of DG and cloud covering PV field are simulated with and without BESS in order to clearly determine its influence on system stability.

A comprehensive comparison between three different control strategies for four-leg active power filters

Abstract: This paper presents a comprehensive comparison between three popular control strategies for active power filters (APF). All three strategies are applied to a 4-leg APF which is connected to a 4-wire 3-phase distribution system at the point of common coupling (PCC) where a set of linear, nonlinear, 3-phase, and single phase loads are also connected to the system. All the methods should be able to reduce current's total harmonic distortion (THD) below 5%, eliminate neutral wire's current, and compensate the reactive power simultaneously. All three methods are simulated on a same system and parameters such as THD, system response time, calculation burden, and simulation time are taken into account for comparison. At the end, all three methods are compared to each other in a table and all of their merits and demerits are mentioned. It should be noted that, all the simulations in this paper are done by MATLAB/Simulink.

Grid-connected PV monitoring system (GCPV-MS)

Abstract: This paper presents the concept and operating principles of a flexible real-time long-term monitoring system for photovoltaic (PV) plants. Compared to traditional solutions which require dedicated hardware and/or specific data logging systems, the monitoring system we propose allows the user to monitor the grid-connected PV system using commercial of the shelf hardware devices and software programs such as LabVIEW and Weather Link software. The proposed system is built around wired/wireless devices and internet of things (IoT) concept. It provides customizable fast, reliable and secure monitoring tool suitable for deployment in PV systems management. The grid-connected PV monitoring system (GCPV-MS) is developed and installed at the University of Huddersfield, United Kingdom. The results obtained from this project indicate how IoT concept can be utilized in remote PV monitoring systems.

Genetic optimisation for a stochastic model for opportunistic maintenance planning of offshore wind farms

Abstract: The cost incurred from operations and maintenance activity for offshore wind turbines contributes significantly to the overall lifecycle cost for offshore wind farms. This work addresses the issue of identifying a near-optimal schedule for the planning of operations and maintenance activity for the turbines in an offshore wind farm. Significant cost savings can be realized by scheduling maintenance tasks at times of predicted low power production. This research implements a rolling horizon stochastic model and applies meta-heuristic optimization techniques to identify a near-optimal schedule for the opportunistic maintenance of wind farms. Empirical evaluation of the proposed approach produces schedules that achieve a cost saving in the range of 13–21% over standard techniques.

Energy management system for energy efficiency improvement in the industrial sector of the republic of Serbia

Abstract: Main primary energy sources in Serbia are coal, oil and natural gas, oil shale and renewable energy sources. The share of high quality primary energy sources (oil and natural gas) is less than 1% of total geological reserves, while the rest of 99% consists of different types of coal, with highest share of lignite — over 95%. Estimated technically available renewable energy sources potential in Serbia is 5.65 Mtoe, where 1.054 Mtoe of biomass and 0.909 Mtoe of hidro-power are already used. Speaking of energy efficiency in final energy consumption sectors of the Republic of Serbia holds unenviable position comparing to EU countries. Since 2000 there is series of strategic and legal documents that are adopted and they are governing the operation of energy sector as well as implementation of energy policy at state level. The Law on energy efficiency was adopted in March 2013. It regulates implementation of energy management system within industrial sector, on the local level (cities and municipalities) as well as in public buildings sector. The purpose of secondary legislative is to define, in more details, terms for obtaining status of designated company within the system for energy management in industrial sector and in public companies, training programs for energy managers, as well as method of appointing energy managers in designated companies.

Machine learning techniques for short-term load forecasting

Abstract: Selection of an adequate tool for accurate short-term load forecasting task is becoming more important for electric utilities. Machine learning techniques are proving useful for short-term electricity load forecasting. In this paper we evaluate performance of several machine learning algorithms applied to electricity load datasets. We evaluated performance of SMOreg, and Additive regression algorithms for load forecasting using electricity consumption datasets. We also performed an Artificial Neural Networks (ANN) analysis on short-term load forecasting.

Energy balances of South East European countries with the emphasis on the influences of renewable energy sources

Abstract: This paper at its very beginning presents the realized electricity production by type of used primary energy sources, with the emphasis on the renewable sources, consumption and exchange of electricity over the past ten years for all of the countries of South Eastern Europe. After that, an analysis of the key energy aspects in the observed period is given. Further on, breakdown of renewable energy sources by type is given, and its development over the last decade is presented and analyzed. For the year 2015, production from renewable energy sources of several countries from the region, which are the biggest ones in the segment of electricity production, is presented in more detail. Short review of the relevant European legislation that covers this area is also presented, and is followed with the conclusion of how to treat renewable energy sources installment and production in the following years in order to successfully meet the so called 2020 targets.

GreenSoul∗ a novel platform for the reduction of energy consumption in communal and shared spaces

Abstract: In order to achieve higher energy efficiency in buildings, it is essential that devices be consciously used. The GreenSoul project aims to build energy awareness to users and help them change their energy consumption behavior. This will be succeeded by changing the way people use energy consuming devices and by embedding intelligence in the devices themselves, which could autonomously decide about their operation mode and energy consumption. GreenSoul research and innovation focus on the reduction of the energy consumption above 20%, within the domain of public buildings or buildings of public use. GreenSoul forecasts that it is possible to surpass this target providing that a true collaboration among people, devices and buildings is achieved by putting in place the range of technological contributions set forward by this project.

Novel proportional-integral-resonant current controller for three phase PWM converters

Abstract: In this paper a novel current control algorithm for a pulsewidth modulation (PWM) voltage-source converters is proposed, based on the reduced order generalized integrator (ROGI). Namely, existing ROGI based algorithms include proportional (P) and resonant (R) control action, while the integral (I) action was not, so far, combined with ROGI. Furthermore, since proportional-integral-resonant (PIR) controllers are employed in control of various three-phase PWM converters, in this paper the P-ROGI controller is combined with an integral control action in order to enable its use in the same field of application as PIR. Consequently, the novel PI-ROGI control algorithm is presented in the paper, and implemented in AC current control of a three phase PWM rectifier. The novel controller performance is verified by means of simulation.

Constrained state feedback control of DC-DC power converter based on model predictive approach

Abstract: This paper presents novel constrained state feedback controller designed for SiC MOSFET DC-DC power converter. First, discrete state feedback controller (SFC) with feedforward path and load-current observer is proposed. Next, model predictive approach (MPAC) is used to a posteriori constraint introduction into control system. The proposed control scheme is tested through experiments at switching-frequency of 32 kHz, regarding reference and load variations. It is shown that, thanks to the introduction of model predictive approach constraint into control system, a much better dynamic behavior was obtained, in comparison to non-constrained state feedback control.

Modeling of the occurrence of fire in closed cars garages

Abstract: In the current work is provided a physical and mathematical model of fire over a burning car. The solution of the model is based on the integral method. Provided is an algorithm of the numerical solution and its relevance is proven.

New harvesting system based on photovoltaic cells with antireflexive ZnO nanoparticles coatings and DC/DC isolation conversion

Abstract: In this paper we propose a new design of havesting system based on photovoltaic cells with antireflexive ZnO nanoparticles coatings and DC/DC isolation conversion. The system is based on an assembly of four photovoltaic polycrystalline cells provided with antireflexive ZnO nanoparticles coatings. The solar cells have been tested in terms of efficiency and output power for irradiance values in the range of 100 W/m2 — 1000 W/m2. The system of photovoltaic cells generates and transfers the energy to a DC/DC converter with galvanic separation. The converter uses a micro transformer with planar coils, ferrite magnetic circuit and magnetic colloidal nanofluid. The proposed model of micro transformer has been tested independently for frequencies of 100 kHz, 300 kHz and 500 kHz (which stands as the commutation frequency of the DC/DC converter), showing an efficient operation. The inductivity measurement proves that the inductivity of the primary winding is similar to the optimum inductivity of the DC/DC converter indicated by Texas Instruments manufacturing company which uses the LM 25017 integrated electronic circuit.

Experimental analysis on drag coefficient reduction techniques

Abstract: Drag reduction geometries is one of the burning issues in the present aerodynamics on which vast range of work is going on. Generally drag is the force exerted by the medium on the vehicles in the direction linear to the motion of the medium. Many of the researchers have developed some techniques like spike attachment to the front nose of the body, breathing blunt nosed body, splitter plate, fore body surface roughness, rounding the vertical corners of vehicles, making small holes to the model. The study of flow past the blunt nosed body with spikes having different overhead geometries like spike, double arrowed spike, semicircle, semicircle with arrow are studied. In this the flow past the blunt nosed body is studied experimentally. The flow parameter drag coefficient is calculated for different Reynolds number using drag co-efficient relations and results obtained are validated. The experimentation is carried in an open type channel. The present research involves calculation of drag co-efficient for blunt nosed body with different overhead geometries. The focus of the present research is on finding the drag coefficient both by experimentally and analytically.

Importance of lightning activity monitoring systems in transient analysis on wind turbine blade

Abstract: Lightning Activity Monitoring System (LAMS) provides very important data for transient analysis. This paper describes a new lightning activity monitoring system installed on the mountain Lovcen. First measurement data are shown and their importance in transient analysis due to direct lightning strokes on wind turbine blade is explained. This paper describes complete model for wind turbines testing under different lightning current shapes developed in EMTP — RV.

Contribution for limiting and testing network policies

Abstract: Since the data transmission networks require different bandwidth for simultaneous transmission of data, the new generation of network equipment use technologies that ensure QoS (Quality of Service) control services integrated data, video, voice and multimedia. This paper, demonstrate the test evaluation possibility of QoS parameters in a switch and the bandwidth limitation.

Backstepping control and energy management of hybrid DC source based electric vehicle

Abstract: This paper presents a power management and backstepping control of electric vehicle DC power source. The hybrid DC power source consists of two energy sources: a fuel cell (FC) as a main source and battery as an auxiliary source; these sources are linked to the DC-bus through tow DC-DC power converters. The main focuses of this study is to ensure the power requirement of the traction machine using an appropriate power management strategy, to guarantee a good DC-bus regulation, and satisfactory tracking of the fuel cell and battery currents to their references. Simulations results are presented to verify the effectiveness of the proposed control strategy. These simulations are performed using the new European drive cycle (NEDC).

Intelligent industrial measurement instruments with silicon piezoresistive MEMS pressure sensors

Abstract: In this paper we first describe the latest silicon piezoresistive MEMS pressure sensor developed and manufactured at the Center of Microelectronic Technologies (ICTM-CMT). We introduce the concept of intelligent industrial instrumentation, and present a method that enables simultaneous high-performance pressure and temperature measurement to be realized using the described sensor. Experimental verification of the method was performed using the intelligent industrial instrument platform developed at ICTM-CMT. The obtained results have been discussed. They indicate that it is possible to meet or exceeded the measurement performance of existing industrial-grade equipment by using the described approach. An important advantage of the method is that it can enable the temperature measurement capability to be added to some existing intelligent transmitters without hardware modifications. A new intelligent industrial liquid level transmitter, based on the described method and developed at IHTM-CMT, is also presented.

Effect of small deviation of incident angle on thermal performance of parabolic-trough solar collector

Abstract: The paper analyzes the effect of small deviation of incident angle relative to the focal plane on thermal performance of parabolic-trough solar collector. Decrease of solar collector thermal output is presented in form of coefficient of performance i.e. function of the incident angle deviation. In solar collector operation mode, working fluid (e.g. water) can become overheated. In that case, decreasing the thermal output would influence temperature drop of working fluid. Rotation of a parabola for a small angle relative to the focal plane will decrease the output thermal power of the solar collector. This analysis contributes to calculate deviation of incident angle relative to the focal plane in order to achieve the given thermal output for defined input parameters — collector type, local and real conditions (i.e. Sun position, orientation, time and date). In this paper, two-dimensional analytic geometry was used as a basic methodology for calculations and simulations.

The possibility of replacing solid walls with water curtain applicable to a large underground garage

Abstract: In current work is consider a replacement of fire barriers with hard water curtain sprinkler system created by the devices. The main focus is the duration of activation of the sprinkler devices and parameters therefore generating a water curtain. It represents isolated to specific car cells using water curtain to prevent the spread of fire to neibouring and adjacent cars.

High temperature energy storage based on hot air turbine and pebble-heater technology

Abstract: The HiTES energy storage is a high temperature thermal electric energy storage. It consists of a heating coil, a heat storage and a recuperated hot air turbine. HiTES can be applied to smooth out intermittency due to renewable energy sources, for load control, or other flexibility options. The low investment cost and the high efficiency make the HiTES energy storage economically feasible even today. The economic feasibility can be increased by improvements of the round trip efficiency and by decreasing investment costs. For that reason several improvements scenarios were analyzed. The most correct comparison between different energy storage systems is based on the levelized cost of the electricity storage — LCOES. It shows that HiTES is more economic than lithium ion batteries. The paper gives a short parametric analysis of the main parameters that influence the levelized cost of energy storage, like the specific investment cost, the round-trip efficiency and the price of the input electricity.

Hybrid solar — wind power plants — simulation of a daily cycle and the criteria for the connection to the power grid

Abstract: Renewable energy sources in addition to all the advantages over the non-renewable energy sources have a lot of limitations, where the biggest of them are the price and the inability of constant electricity generation. One way of overcoming the problem of inability of constant electricity generation is to build hybrid power plants with renewable energy sources. This primarily highlights hybrid solar — wind power plants, which produce electricity by using solar radiation and wind energy. Since the hybrid solar — wind power plants consist of a photovoltaic power plant and a wind power plant and are usually constructed as a distributed source, it is necessary that the regulatory frameworks define criteria and actions for the connection of a hybrid solar — wind power plant in the power system. This paper gives a short overview of criteria and actions for the connection of a hybrid solar — wind power plant in the power system according to official documents in Bosnia and Herzegovina.

A characterization method for identifying the piezoelectric bending beam energy harvesters

Abstract: This paper presents a characterization method for measuring model parameters of a piezoelectric bending beam energy harvester. In the proposed method, all parameters except coupling coefficient are obtained through a simple electrical test which facilitates the characterization procedure and enhances the accuracy of measurements. In the suggested method, the frequency response of output voltage and current of the beam under short-circuit and open-circuit conditions will be compared with the frequency response of analytical model of the beam. Then, by minimization of the matching error, an estimation of the model parameters including mechanical damping, electrical coupling, beam capacitance, resonant frequency and coupling coefficient will be obtained. The proposed method does not require measurement of the tip deflection of the beam. This feature will simplify the characterization test setup and also it enables characterization of the sealed package devices in which the tip of the beam is not accessible. This performance of the method is verified using an experimental test setup and it is successfully used for characterization of a cm-scale piezoelectric beam.

Discussing single phase PWM voltage source inverters with different frequency modulation factors

Abstract: This paper presents two designs for a single phase, voltage source inverters using Pulse Width Modulation (PWM) control with different frequency modulation values and compares between them. One design adopted a triangular carrier signal that is 250 times faster than the reference, i.e. with frequency modulation factor of 250, and the other design demonstrated a carrier signal with frequency modulation factor of 500. Both designs were simulated using Matlab Simulink and implemented in hardware then compared in terms of Total Harmonic Distortion (THD), efficiency, speed and size.

The potential of the water hammer in pico-scale tidal power systems: An experimental investigation

Abstract: The tidal energy within the seas surrounding the United Kingdom offers a vast renewable resource that is perfectly predictable over long timescales. Currently, the bulk of tidal energy research is focused on developing large devices for the most resource rich locations, which can be many miles from populated areas. The potential of small-scale tidal power from sub-optimal shallow water sites, close to populated regions, has so far been overlooked. Such generation would benefit from reduced transmission losses and contribute towards a distributed electricity grid, helping to overcome the variability of other renewables. This work presents a novel method for generating hydropower using the water hammer effect: a pressure surge that can occur in a pipeline following the abrupt closure of a valve. These pressure surges are used to produce vertical oscillations from horizontally flowing water, allowing power to be generated in a manner analogous to a wave energy convertor. A non-optimised scale model was found experimentally to have a peak available power density of 1.08 ± 0.25 kW/m2 and a mean of 0.07 ± 0.02 kW/m2. In comparison, the MCT SeaGen S (arguably the most well-developed tidal energy device) is capable of generating 3.18 kW/m2. With further development, a water hammer device may therefore be useful for generating pico-scale tidal power in slow, shallow water flows.