Records Added in February 2019
Records added in February 2019
Change year: 2018 | 2019
Change month: January | February
Showing records 1 to 25 of 67. [First] Page: 1 2 3 Last
Aluminum⁻Titanium Alloy Back Contact Reducing Production Cost of Silicon Thin-Film Solar Cells
Hsin-Yu Wu, Chia-Hsun Hsu, Shui-Yang Lien, Yeu-Long Jiang
February 5, 2019 (v1)
Subject: Materials
Keywords: aluminum–titanium (AlTi) alloy, contact resistance, silicon thin-film solar cells
In this study, metal films are fabricated by using an in-line reactive direct current magnetron sputtering system. The aluminum⁻titanium (AlTi) back contacts are prepared by changing the pressure from 10 mTorr to 25 mTorr. The optical, electrical and structural properties of the metal back contacts are investigated. The solar cells with the AlTi had lower contact resistance than those with the silver (Ag) back contact, resulting in a higher fill factor. The AlTi contact can achieve a solar cell conversion efficiency as high as that obtained from the Ag contact. These findings encourage the potential adoption of AlTi films as an alternative back contact to silver for silicon thin-film solar cells.
Experimental Investigation of Thermal Behaviors in Window Systems by Monitoring of Surface Condensation Using Full-Scale Measurements and Simulation Tools
Goopyo Hong, Daeung Danny Kim, Byungseon Sean Kim
February 5, 2019 (v1)
Subject: Other
Keywords: chamber, condensation, spacer, window
The aim of the present study was to investigate the thermal performance of window systems using full-scale measurements and simulation tools. A chamber was installed on the balcony of an apartment to control the temperatures which can create condensation on the interior surfaces of window systems. The condensation process on the window was carefully scrutinized when outdoor and indoor temperature and indoor relative humidity ranged from −15 °C to −20 °C, 23 °C to 24 °C, and 50% to 65%, respectively. The results of these investigations were analyzed to determine how the moisture is influenced by changing temperatures. It appears that the glass-edge was highly susceptible to the temperature variations and the lowest temperature on the glass edge was caused by the heat transfer through the spacer, between the two glass panels of the window. The results from the simulation used in this study confirm that the thermal performance of window systems can be improved the use of super insulated o... [more]
A Three-Stage Optimal Approach for Power System Economic Dispatch Considering Microgrids
Wei-Tzer Huang, Kai-Chao Yao, Chun-Ching Wu, Yung-Ruei Chang, Yih-Der Lee, Yuan-Hsiang Ho
February 5, 2019 (v1)
Keywords: distributed energy resources, economic dispatch, improved direct search method, linear programming, microgrid, multi-area
The inclusion of microgrids (MGs) in power systems, especially distribution-substation-level MGs, significantly affects power systems because of the large volumes of import and export power flows. Consequently, power dispatch has become complicated, and finding an optimal solution is difficult. In this study, a three-stage optimal power dispatch model is proposed to solve such dispatch problems. In the proposed model, the entire power system is divided into two parts, namely, the main power grid and MGs. The optimal power dispatch problem is resolved on the basis of multi-area concepts. In stage I, the main power system economic dispatch (ED) problem is solved by sensitive factors. In stage II, the optimal power dispatches of the local MGs are addressed via an improved direct search method. In stage III, the incremental linear models for the entire power system can be established on the basis of the solutions of the previous two stages and can be subjected to linear programming to dete... [more]
Improving the Stability and Accuracy of Power Hardware-in-the-Loop Simulation Using Virtual Impedance Method
Xiaoming Zha, Chenxu Yin, Jianjun Sun, Meng Huang, Qionglin Li
February 5, 2019 (v1)
Subject: Other
Keywords: accuracy, impedance model, power hardware-in-the-loop, stability, virtual impedance
Power hardware-in-the-loop (PHIL) systems are advanced, real-time platforms for combined software and hardware testing. Two paramount issues in PHIL simulations are the closed-loop stability and simulation accuracy. This paper presents a virtual impedance (VI) method for PHIL simulations that improves the simulation’s stability and accuracy. Through the establishment of an impedance model for a PHIL simulation circuit, which is composed of a voltage-source converter and a simple network, the stability and accuracy of the PHIL system are analyzed. Then, the proposed VI method is implemented in a digital real-time simulator and used to correct the combined impedance in the impedance model, achieving higher stability and accuracy of the results. The validity of the VI method is verified through the PHIL simulation of two typical PHIL examples.
An Improved Adaptive-Torque-Gain MPPT Control for Direct-Driven PMSG Wind Turbines Considering Wind Farm Turbulences
Xiaolian Zhang, Can Huang, Sipeng Hao, Fan Chen, Jingjing Zhai
February 5, 2019 (v1)
Keywords: adaptive torque gain control, maximum power point tracking (MPPT), turbulence intensity, wind energy conversion system (WECS), wind turbine
Maximum power point tracking (MPPT) plays an important role in increasing the efficiency of a wind energy conversion system (WECS). In this paper, three conventional MPPT methods are reviewed: power signal feedback (PSF) control, decreased torque gain (DTG) control, and adaptive torque gain (ATG) control, and their potential challenges are investigated. It is found out that the conventional MPPT method ignores the effect of wind turbine inertia and wind speed fluctuations, which lowers WECS efficiency. Accordingly, an improved adaptive torque gain (IATG) method is proposed, which customizes adaptive torque gains and enhances MPPT performances. Specifically, the IATG control considers wind farm turbulences and works out the relationship between the optimal torque gains and the wind speed characteristics, which has not been reported in the literature. The IATG control is promising, especially under the ongoing trend of building wind farms with large-scale wind turbines and at low and med... [more]
Accelerated Model Predictive Control for Electric Vehicle Integrated Microgrid Energy Management: A Hybrid Robust and Stochastic Approach
Zhenya Ji, Xueliang Huang, Changfu Xu, Houtao Sun
February 5, 2019 (v1)
Keywords: Benders decomposition, electric vehicle, energy management system, microgrid, robust optimization, scenario-based model predictive control, Stochastic Optimization
A microgrid with an advanced energy management approach is a feasible solution for accommodating the development of distributed generators (DGs) and electric vehicles (EVs). At the primary stage of development, the total number of EVs in a microgrid is fairly small but increases promptly. Thus, it makes most prediction models for EV charging demand difficult to apply at present. To overcome the inadaptability, a novel robust approach is proposed to handle EV charging demand predictions along with demand-side management (DSM) on the condition of satisfying each EV user’s demand. Variables with stochastic forecast models join the objective function in the form of probability-constrained scenarios. This paper proposes a scenario-based model predictive control (MPC) approach combining both robust and stochastic models to minimize the total operational cost for energy management. To overcome the concern about the convergence time increasing from the combination of scenarios, the Benders dec... [more]
Improved Direct Deadbeat Voltage Control with an Actively Damped Inductor-Capacitor Plant Model in an Islanded AC Microgrid
Jaehong Kim, Jitae Hong, Hongju Kim
February 5, 2019 (v1)
Keywords: deadbeat control, distributed generators (DGs), inverters, microgrid, uninterruptible power supply (UPS)
A direct deadbeat voltage control design method for inverter-based microgrid applications is proposed in this paper. When the inductor-capacitor (LC) filter output voltage is directly controlled using voltage source inverters (VSIs), the plant dynamics exhibit second-order resonant characteristics with a load current disturbance. To effectively damp the resonance caused by the output LC filter, an active damping strategy that does not cause additional energy loss is utilized. The proposed direct deadbeat voltage control law is devised from a detailed, actively damped LC plant model. The proposed deadbeat control method enhances voltage control performance owing to its better disturbance rejection capability than the conventional deadbeat or proportional-integral-based control methods. The most important advantage of the proposed deadbeat control method is that it makes the deadbeat control more robust by bringing discrete closed-loop poles closer to the origin. Simulation and experimen... [more]
Failure Criteria of Gas-Infiltrated Sandy Shale Based on the Effective Stress Principle
Wenpu Li, Dongming Zhang, Minghui Li
February 5, 2019 (v1)
Subject: Other
Keywords: effective stress, failure criterion, gas-infiltrated sandy shale, rock strength, triaxial compression test
Pore gas has a significant influence on rock strength. This study performed triaxial compression tests of gas-infiltrated sandy shale samples to investigate the strength characteristics under gas pressures of 0 and 2 MPa. The effective stress coefficient was evaluated while considering the gas and solid coupling effect, and was found to decrease with increasing confining pressure. The calculated and different assumed coefficient values (0 and 1) were applied to obtain the effective principal stress. The experimental results would serve as fundamental strength data for fitting analysis in failure criterion work. The Mohr-Coulomb, Hoek-Brown, Drucker-Prager, linear Mogi, and non-linear Mogi criteria were modified based on the effective stress principle of porous rock. In addition, the RMSE, cohesion, and internal friction angle were utilized for a quantitative criterion comparison. The results showed that the Mohr-Coulomb, Drucker-Prager, and linear Mogi failure criteria led to higher er... [more]
Multi-Objective Optimization of a Solar Chimney Power Plant with Inclined Collector Roof Using Genetic Algorithm
Ehsan Gholamalizadeh, Man-Hoe Kim
February 5, 2019 (v1)
Keywords: inclined collector roof, multi-objective genetic algorithm, Renewable and Sustainable Energy, solar chimney power plant
This paper presents an optimization of a solar chimney power plant with an inclined collector roof using genetic algorithms. Five design parameters that affect the system performance are the collector radius, collector inlet height, collector outlet height, chimney height and diameter. A multi-objective design to simultaneously optimize three conflicting objectives including system efficiency, power output and expenditure is used. Based on this approach, obtaining the best combination of the possible geometrical parameters, performance of two built pilot power plants in Kerman (Iran) and Manzanares (Spain) are optimized thermo-economically. The heights of the zero-slope collectors of the Kerman and Manzanares systems are 2 m and 1.85 m, respectively. The results show that in the Kerman pilot the optimal collector inlet and outlet heights are 1.5 m and 2.95 m, respectively, while those optimal heights in the Manzanares prototype are 1.5 m and 4.6 m, respectively. It is found that select... [more]
Suitability Assessment of an ICE-Based Micro-CCHP Unit in Different Spanish Climatic Zones: Application of an Experimental Model in Transient Simulation
Guillermo Rey, Carlos Ulloa, José Luís Míguez, Antón Cacabelos
February 5, 2019 (v1)
Keywords: Código Técnico de la Edificación (CTE), heating and power, internal combustion engine (ICE), micro-combined cooling, TRNSYS
Tri-generation plants will have an important role in the near future in the residential sector where heating and cooling demands come into play throughout the year. Depending on the building’s location, the characteristics of its enclosure and its use, the thermal loads and demands will be different. This article analyses and compares a combined cooling, heating and power (CCHP) system tested in the laboratory and a single household located in Spain. The cooling capacity is obtained using a reversible heat pump where the compressor is driven directly by a gas engine with internal combustion engine (ICE) technology. The tests were carried out in a work bench at three different operating speeds. A variable-speed model is developed in the TRNSYS simulation environment with an operating strategy following the thermal load (FTL). Once the micro-CCHP system was modeled with experimental data and validated, it was dynamically simulated to analyze its performance in different climatic zones de... [more]
A Review of Factors Influencing the Cost Development of Electricity Generation Technologies
Sascha Samadi
February 5, 2019 (v1)
Subject: Energy Policy
Keywords: cost development, economies of scale, electricity generation technologies, literature review, technological learning
This article reviews the literature on the past cost dynamics of various renewable, fossil fuel and nuclear electricity generation technologies. It identifies 10 different factors which have played key roles in influencing past cost developments according to the literature. These 10 factors are: deployment-induced learning, research, development and demonstration (RD&D)-induced learning, knowledge spillovers from other technologies, upsizing, economies of manufacturing scale, economies of project scale, changes in material and labour costs, changes in fuel costs, regulatory changes, and limits to the availability of suitable sites. The article summarises the relevant literature findings for each of these 10 factors and provides an overview indicating which factors have impacted on which generation technologies. The article also discusses the insights gained from the review for a better understanding of possible future cost developments of electricity generation technologies. Finall... [more]
Long Term Expected Revenue of Wind Farms Considering the Bidding Admission Uncertainty
Mazaher Haji Bashi, Gholamreza Yousefi, Claus Leth Bak, Jayakrishnan Radhakrishna Pillai
February 5, 2019 (v1)
Keywords: bidding Admission uncertainty, Genetic Algorithm, long term bidding behavior, market price uncertainty, PAB and UP auctions, wind farm expected revenue
As a long term bidding behavior, bid shading is exhibited by wind farms participating in real Uniform Price (UP) markets. This signifies that the wind farm owners bid far below their true long run marginal cost. In this paper, a method is proposed to consider the uncertainty of bidding admission in the long term expected revenue of wind farms. We show that this consideration could perfectly explain the observed bid shading behavior of wind farm owners. We use a novel market price model with a stochastic model of a wind farm to derive indices describing the uncertainty of bidding admission. The optimal behavior of the wind farm is then obtained by establishing a multi objective optimization problem and subsequently solved using genetic algorithm. The method is applied to the analysis of long term bidding behavior of a wind farm participating in a Pay-as-Bid (PAB) auction such as Iran Electricity Market (IEM). The results demonstrate that wind farm owners change their bid shading behavio... [more]
A Detailed Assessment of the Wave Energy Resource at the Atlantic Marine Energy Test Site
Reduan Atan, Jamie Goggins, Stephen Nash
February 5, 2019 (v1)
Subject: Energy Policy
Keywords: Atlantic Marine Energy Test Site (AMETS), extreme waves, operational waves, Simulating WAves Nearshore (SWAN), wave characterisation, wave energy resource, wave power, wave resource variability
Wave characteristic assessments of wave energy test sites provide a greater understanding of prevailing wave conditions and are therefore extremely important to both wave energy test site operators and clients as they can inform wave energy converter design, optimisation, deployment, operation and maintenance. This research presents an assessment of the wave resource at the Atlantic Marine Energy Test Site (AMETS) on the west coast of Ireland based on 12-years of modelled data from January 2004 to December 2015. The primary aim is to provide an assessment of annual and seasonal wave characteristics and resource variability at the two deployment berths which comprise the site. A nested model has been developed using Simulating WAves Nearshore (SWAN) to replicate wave propagations from regional to local scale with a 0.05° resolution model covering the northeast Atlantic and a 0.0027° resolution model covering AMETS. The coarse and fine models have been extensively validated against avail... [more]
The Effect of Biogas Production on Farmland Rental Prices: Empirical Evidences from Northern Italy
Eugenio Demartini, Anna Gaviglio, Marco Gelati, Daniele Cavicchioli
February 5, 2019 (v1)
Subject: Energy Policy
Keywords: agricultural fixed resource, agricultural land price, bioenergy, biogas, environmental trilemma, farmland rental price, farmland value, land use, rent, social sustainability
In the last decade, increased environmental awareness has prompted the adoption of incentives for exploiting renewable energy sources. Among these, biogas production has received a certain attention in developed countries. Nonetheless, the subsidies provided have posed the problem of an activity (the production of bioenergy) that engages in direct competition with food and feed production for limited resources, like agricultural land. Even if this competition may be softened by allocating marginal land and/or using dedicated non-agricultural crops, empirical evidence shows that biogas plants have been developed in highly-productive agricultural areas, using increasing amounts of maize silage as feedstock. Thus, studies aimed at measuring the effect of biogas production on agricultural activities are needed in order to avoid this socially undesirable outcome. The paper presents an econometric estimation of the impact of biogas plants on farmland rental values of a Northern Italian rural... [more]
An Overview of Modeling Approaches Applied to Aggregation-Based Fleet Management and Integration of Plug-in Electric Vehicles †
Shi You, Junjie Hu, Charalampos Ziras
February 5, 2019 (v1)
Keywords: aggregation-based, fleet, integration, modeling approaches, plug-in electric vehicle
The design and implementation of management policies for plug-in electric vehicles (PEVs) need to be supported by a holistic understanding of the functional processes, their complex interactions, and their response to various changes. Models developed to represent different functional processes and systems are seen as useful tools to support the related studies for different stakeholders in a tangible way. This paper presents an overview of modeling approaches applied to support aggregation-based management and integration of PEVs from the perspective of fleet operators and grid operators, respectively. We start by explaining a structured modeling approach, i.e., a flexible combination of process models and system models, applied to different management and integration studies. A state-of-the-art overview of modeling approaches applied to represent several key processes, such as charging management, and key systems, such as the PEV fleet, is then presented, along with a detailed descri... [more]
Expert Opinion Analysis on Renewable Hydrogen Storage Systems Potential in Europe
Davide Astiaso Garcia, Federica Barbanera, Fabrizio Cumo, Umberto Di Matteo, Benedetto Nastasi
February 5, 2019 (v1)
Subject: Energy Policy
Keywords: economic aspects, expert opinion analysis, hydrogen storage systems, power to gas, renewable hydrogen
Among the several typologies of storage technologies, mainly on different physical principles (mechanical, electrical and chemical), hydrogen produced by power to gas (P2G) from renewable energy sources complies with chemical storage principle and is based on the conversion of electrical energy into chemical energy by means of the electrolysis of water which does not produce any toxic or climate-relevant emission. This paper aims to pinpoint the potential uses of renewable hydrogen storage systems in Europe, analysing current and potential locations, regulatory framework, governments’ outlooks, economic issues, and available renewable energy amounts. The expert opinion survey, already used in many research articles on different topics including energy, has been selected as an effective method to produce realistic results. The obtained results highlight strategies and actions to optimize the storage of hydrogen produced by renewables to face varying electricity demand and generation-dri... [more]
Study on the Static Load Capacity and Synthetic Vector Direct Torque Control of Brushless Doubly Fed Machines
Chaoying Xia, Xiaoxin Hou
February 5, 2019 (v1)
Keywords: brushless doubly fed machine (BDFM), load capacity, losing control, state-space model, synthetic vector direct torque control (SVDTC)
Compared to the doubly fed machine, the brushless doubly fed machine (BDFM) has high reliability and low maintenance requirements. First, by taking the negative conjugation of the control motor variables in rotor reference frame, a state-space model of BDFM is derived. It is then transformed into synchronous reference frame, called synchronous reference frame state-space model (SSSM). In this way, all the variables of the SSSM are DC under the static state. Second, on the basis of the analysis of static equations, the possible output torque limits are obtained. Third, the causes of losing control are analyzed by the flux and the torque derivatives. A new control strategy called synthetic vector direct torque control (SVDTC) is proposed to solve the losing control problems of the conventional direct torque control (DTC). Finally, the correctness of the results of this paper is verified by calculation examples and simulation results, the losing control problems can be solved, and the the... [more]
Estimation of Energy Consumption and Greenhouse Gas Emissions of Transportation in Beef Cattle Production
Narayanan Kannan, Ali Saleh, Edward Osei
February 5, 2019 (v1)
Subject: Energy Policy
Keywords: animal trailer, beef-cattle, CO2 equivalent, Energy, gooseneck, greenhouse gas, life cycle analysis (LCA), model, pot belly, transportation
Accounting for transportation is an important part of the life cycle analysis (LCA) of beef cattle production because it is associated with energy consumption and greenhouse gas emissions. This paper describes the development and application of a model that estimates energy consumption and greenhouse gas emissions of transport in beef cattle production. The animal transport model is based on the weight and number of animals in each weight category, type of trailer, vehicle, and fuel used. The energy consumption and greenhouse gas emission estimates of animal feed transportation are based on the weight of a truckload and the number of truckloads of feed transported. Our results indicate that a truckload is travelling approximately 326 km in connection with beef cattle production in the study region. The fuel consumption amounts to 24 L of fossil fuel per 1000 kg of boneless beef. The corresponding greenhouse gas emission is 83 kg. It appears from our results that the majority of energy... [more]
Parametric Density Recalibration of a Fundamental Market Model to Forecast Electricity Prices
Antonio Bello, Derek Bunn, Javier Reneses, Antonio Muñoz
February 5, 2019 (v1)
Keywords: densities, electricity, forecasting, fundamentals, hybrid, prices
This paper proposes a new approach to hybrid forecasting methodology, characterized as the statistical recalibration of forecasts from fundamental market price formation models. Such hybrid methods based upon fundamentals are particularly appropriate to medium term forecasting and in this paper the application is to month-ahead, hourly prediction of electricity wholesale prices in Spain. The recalibration methodology is innovative in seeking to perform the recalibration into parametrically defined density functions. The density estimation method selects from a wide diversity of general four-parameter distributions to fit hourly spot prices, in which the first four moments are dynamically estimated as latent functions of the outputs from the fundamental model and several other plausible exogenous drivers. The proposed approach demonstrated its effectiveness against benchmark methods across the full range of percentiles of the price distribution and performed particularly well in the tai... [more]
Novel Auto-Reclosing Blocking Method for Combined Overhead-Cable Lines in Power Networks
Ricardo Granizo Arrabé, Carlos Antonio Platero Gaona, Fernando Álvarez Gómez, Emilio Rebollo López
February 5, 2019 (v1)
Keywords: distribution protections, electrical distribution networks, ground faults, protection
This paper presents a novel auto-reclosing blocking method for combined overhead-cable lines in power distribution networks that are solidly or impedance grounded, with distribution transformers in a delta connection in their high-voltage sides. The main contribution of this new technique is that it can detect whether a ground fault has been produced at the overhead line side or at the cable line side, thus improving the performance of the auto-reclosing functionality. This localization technique is based on the measurements and analysis of the argument differences between the load currents in the active conductors of the cable and the currents in the shields at the cable end where the transformers in delta connection are installed, including a wavelet analysis. This technique has been verified through computer simulations and experimental laboratory tests.
Linearization and Control of Series-Series Compensated Inductive Power Transfer System Based on Extended Describing Function Concept
Kunwar Aditya, Sheldon Williamson
February 5, 2019 (v1)
Keywords: and transportation, chargers, Energy Storage, inductive energy storage, power electronics, resonant power conversion
The extended describing function (EDF) is a well-known method for modelling resonant converters due to its high accuracy. However, it requires complex mathematical formulation effort. This paper presents a simplified non-linear mathematical model of series-series (SS) compensated inductive power transfer (IPT) system, considering zero-voltage switching in the inverter. This simplified mathematical model permits the user to derive the small-signal model using the EDF method, with less computational effort, while maintaining the accuracy of an actual physical model. The derived model has been verified using a frequency sweep method in PLECS. The small-signal model has been used to design the voltage loop controller for a SS compensated IPT system. The designed controller was implemented on a 3.6 kW experimental setup, to test its robustness.
An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review
Radhika Vidanage De Silva, Ranjith Pathegama Gamage, Mandadige Samintha Anne Perera
February 5, 2019 (v1)
Subject: Other
Keywords: expansive properties, fracture mechanisms, rock fracturing, soundless cracking demolition agents (SCDAs), volume expansion mechanism
Global energy and material consumption are expected to rise in exponential proportions during the next few decades, generating huge demands for deep earth energy (oil/gas) recovery and mineral processing. Under such circumstances, the continuation of existing methods in rock fragmentation in such applications is questionable due to the proven adverse environmental impacts associated with them. In this regard; the possibility of using more environmentally friendly options as Soundless Chemical Demolition Agents (SCDAs) play a vital role in replacing harmful conventional rock fragmentation techniques for gas; oil and mineral recovery. This study reviews up to date research on soundless cracking demolition agent (SCDA) application on rock fracturing including its limitations and strengths, possible applications in the petroleum industry and the possibility of using existing rock fragmentation models for SCDA-based rock fragmentation; also known as fracking. Though the expansive properties... [more]
An Adaptive Speed Control Approach for DC Shunt Motors
Ruben Tapia-Olvera, Francisco Beltran-Carbajal, Omar Aguilar-Mejia, Antonio Valderrabano-Gonzalez
February 5, 2019 (v1)
Keywords: adaptive speed control, DC shunt motors, model-free control, neural networks
A B-spline neural networks-based adaptive control technique for angular speed reference trajectory tracking tasks with highly efficient performance for direct current shunt motors is proposed. A methodology for adaptive control and its proper training procedure are introduced. This algorithm sets the control signal without using a detailed mathematical model nor exact values of the parameters of the nonlinear dynamic system. The proposed robust adaptive tracking control scheme only requires measurements of the velocity output signal. Thus, real-time measurements or estimations of acceleration, current and disturbance signals are avoided. Experimental results confirm the efficient and robust performance of the proposed control approach for highly demanding motor operation conditions exposed to variable-speed reference trajectories and completely unknown load torque. Hence, laboratory experimental tests on a direct current shunt motor prove the viability of the proposed adaptive output f... [more]
Distributed Generation Islanding Effect on Distribution Networks and End User Loads Using the Load Sharing Islanding Method
Maen Z. Kreishan, George P. Fotis, Vasiliki Vita, Lambros Ekonomou
February 5, 2019 (v1)
Keywords: distributed generation, distribution networks, islanding, load sharing, Neplan simulation tool
In this paper a realistic medium voltage (MV) network with four different distributed generation technologies (diesel, gas, hydro and wind) along with their excitation and governor control systems is modelled and simulated. Moreover, an exponential model was used to represent the loads in the network. The dynamic and steady state behavior of the four distributed generation technologies was investigated during grid-connected operation and two transition modes to the islanding situation, planned and unplanned. This study aims to address the feasibility of planned islanding operation and to investigate the effect of unplanned islanding. The load sharing islanding method has been used for controlling the distributed generation units during grid-connected and islanding operation. The simulation results were validated through various case studies and have shown that properly planned islanding transition could provide support to critical loads at the event of utility outages. However, a relia... [more]
Robust Unit Commitment Including Frequency Stability Constraints
Felipe Pérez-Illanes, Eduardo Álvarez-Miranda, Claudia Rahmann, Camilo Campos-Valdés
February 5, 2019 (v1)
Keywords: frequency regulation, inertial response, photovoltaic generation, unit commitment, wind power
An increased use of variable generation technologies such as wind power and photovoltaic generation can have important effects on system frequency performance during normal operation as well as contingencies. The main reasons are the operational principles and inherent characteristics of these power plants like operation at maximum power point and no inertial response during power system imbalances. This has led to new challenges for Transmission System Operators in terms of ensuring system security during contingencies. In this context, this paper proposes a Robust Unit Commitment including a set of additional frequency stability constraints. To do this, a simplified dynamic model of the initial system frequency response is used in combination with historical frequency nadir data during contingencies. The proposed approach is especially suitable for power systems with cost-based economic dispatch like those in most Latin American countries. The study is done considering the Northern I... [more]
Showing records 1 to 25 of 67. [First] Page: 1 2 3 Last
Change year: 2018 | 2019
Change month: January | February