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Smart renewable energy harvesting has been implemented from hybrid sources such as solar and wind. The wireless sensor node is created for monitoring surface water. In the intelligent building, electrical energy is harvested from the hybrid source of solar and wind energy. The source energy was selected for the harvesting process by using a fuzzy controller. In this proposed method, piezo-electric reverse electro-wetting on di-electric energy harvesting is proposed where constant DC voltage is generated by a rectifier. A DC-DC converter is designed to power up the remote read-out sensor. The produced charge is transformed by a charge amplifier with the proportion of output voltage that is delivered to the wireless receiver. The harvested DC voltage varies with the temperature and external environmental effect. In our work, we obtained 6 × 10−3 W/m² of voltage and this harvested energy is monitored using the Internet of Things (IoT) by the proposed EHOR (Energy Harvested Optimized Routing) algorithm. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Donghua University (English Edition) is the property of Journal of Donghua University Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Electric Reliability Council of Texas (ERCOT) is the entity responsible for overseeing the primary electric grid for most of the state of Texas. The ERCOT grid is contained entirely within Texas, serves almost 75% of the state's land area with its 52,700 miles of transmission lines, and provides 90% of the energy used by consumers in the state. Over the last half-century, the ERCOT grid has increasingly experienced intermittency issues that have caused Texas residents major heartaches. After each event, the Texas Legislature and ERCOT have taken steps to ensure that they do not reoccur. Thus far, though, they have failed each and every time to make changes that have a sustained effect on the issues plaguing the grid. Analysis of their attempts at regulation shows that the parties consistently make the same mistakes. These mistakes include hamstringing state regulators' ability to require power generators to make changes; not requiring generators to increase production when extreme conditions are projected; not imposing fines on energy generators whose systems fail in the times of highest need; and placing partisan individuals in positions that should be held by industry experts. Salvaging this situation does not require a complete grid overhaul. It merely requires that the Texas Legislature, ERCOT, and the Public Utility Commission of Texas (PUCT) cooperate to meaningfully regulate electric power generators in the state. This Note shows how. [ABSTRACT FROM AUTHOR]

In most business and residential organizations, Diesel Generators (DG) is a viable supplementary power source for ensuring an undisturbed power supply. The DG is a hybrid machine that generates electrical energy using a Diesel Engine (DE) and an Electric Generator (EG). By routinely monitoring crucial machine parameters, alternative power source efficiency can be improved. Furthermore, Condition Monitoring Systems (CMS) based on the Internet of Things (IoT) have supplanted the traditional equipment maintenance method. Predictive maintenance is also an important building block of Industry 4.0, whose entire process and performance can be fully understood by using IoT-enabled Remote Monitoring (RM) schemes. Firstly, this paper introduces a remote monitoring and data acquisition scheme to realize the concept of predictive maintenance. Secondly, this article discusses a strategy for real-time observation of DG parameters as well as a comprehensive analysis of various metrics. Thirdly, this research article includes a monitoring and analysis scheme of crucial factors in a DG, like the speed of an engine, voltage output, the current produced, power factor, coolant required, fuel consumption, and battery health. Different mathematical models are formulated by correlating experimental data and estimating the coefficients. Finally, to create suitable real-time warnings under critical circumstances, a fuzzy logic-based Decision Support System (DSS) and web-based integration elements are presented. [ABSTRACT FROM AUTHOR]

This paper presents a case study on the steam turbine operation of the 330 MW power group. All the parameters that characterize the operation of the turbine and that are used to determine some quantities in order to appreciate the behavior of the turbine in operation were measured and recordedț. [ABSTRACT FROM AUTHOR]

Bridgeless single-stage converters are used for efficient (alternative current) AC-(direct current) DC conversion. These converters control generators, like electromagnetic meso- and micro-scale generators with low voltage. Power factor correction helps increase the factor of the power supply. The main advantage of the power factor is it shapes the input current for increasing the real power of the AC supply. In this paper, a two-switch bridgeless rectifier topology is designed with a power factor correction capability. For the proposed converter topology to have good power quality parameters, the closed loop scheme, which uses the grey wolf optimization (GWO) algorithm, is implemented. The successes of GWO encourage this research to implement GWO in the topology. The performance of the proposed topology is analyzed under different load conditions. Simulation is carried out using the MATLAB/Simulink environment, and the results are compared with those of conventional (proportional integral derivative) PID and (particle swarm optimization) PSO controllers. To validate the simulation results, a 350-W hardware prototype is implemented, and the voltage ripple, efficiency, and power factor under different load conditions are analyzed and tabulated. The comparative study clearly indicates that the proposed converter topology with a closed loop control scheme using the GWO algorithm improves the power factor to 0.9732 and reduces the voltage ripple to 0.12% with a conversion efficiency of 98.25%. [ABSTRACT FROM AUTHOR]

Automatic Voltage Regulator (AVR) is employed to stabilize the output voltage of generators at electric power plants. However, reliable performance of AVR depends on professional tuning of its PID controller parameters. Therefore, different optimization algorithms are used to determine those parameters. The objective of the optimization is defined as minimizing the characteristics of transient step response such as settling time, rise time, overshoot, and steady state error. Then, to verify the optimization results, a simulator is built experimentally for AVR and PID system which can also be used for other studies on AVR systems. Experimental results are compared with those of MATLAB and Pspice software. Close agreement between the simulation and experimental results confirms the success of the optimization. [ABSTRACT FROM AUTHOR]

The free-piston linear generator (FPLG) with a dual-piston air-driven system is a novel type of energy conversion device that converts mechanical energy into electric power through a linear generator. This paper investigates a novel FPLG utilising different generator stator core configurations (GA, GB, GC, GD, and GD) with an optimised valve opening control and the inlet pressure of 5 bar and 8 bar. The effect of generator configuration on the translator motion characteristics, root mean square (RMS) power output, as well as the system stability and the conversion efficiency, are duly discussed. The results show that the piston motion is affected by the generator configuration and the inlet pressure. The maximum RMS power achieved is 203.9 W when GB is used, whereas the maximum operating frequency of 13.8 Hz and a peak power output of 396 W are achieved when GD is used. The FPLG stability within the range for all generator configurations except for GA when the inlet pressure is 5 bar. The FPLG system conversion efficiency (thermal to work and work to electrical) is duly discussed. [ABSTRACT FROM AUTHOR]

Free piston generators are of interest due to their efficiency, compact construction, and multiple options for combustion. Much of the research into this type of generator has been facilitated by highly-developed internal combustion engine technology. This study was concerned with the design and application of tubular generator. The design model was developed using the matrix laboratory graphical user interface programming tool, and the designed interface was of dynamic type. The sizing of the generator was determined in accordance with the main parameters specified via the interface. In addition, as a benefit of using sizing data, the automatic geometry was formed and analyzed using ANSYS Maxwell software. The magnets and the dynamic part of the tubular-structured generator were shaped polygonally. Numerical analyses were made by adopting the finite element method in the software and construction of the prototype model was based on the results from these findings. The generator was excited by use of the crank rod mechanism to imitate the conditions of a functioning free piston mechanism. Current and voltage values were obtained at mechanical frequencies of 10 Hz and 20 Hz, and this data was subsequently analyzed. Global code translation was given in attachment in order to allow communication between the ANSYS Maxwell and MATLAB GUI software. [ABSTRACT FROM AUTHOR]

Direct-drive permanent magnet synchronous generators enjoy numerous advantages including improved reliability, low maintenance, long life, and developed performance characteristics. In recent years, many researchers have worked on these generators to enhance their performance, especially for the wind turbine application. The focus of this paper is on the development of a step-by-step method for the design of a permanent magnet synchronous generator. Then, the winding function method is used to model the generator and calculate its output characteristics analytically. The analytical results of the designed generator are validated using Finite Element Analysis (FEA) and it is demonstrated that the obtained results from both methods are in great agreement with the experimental measurements of the Northern Power direct-drive generator. The sensitivity analysis and optimization procedure based on genetic algorithm are employed to design an optimum generator. The optimization goal is obtaining higher efficiency and power factor with lower voltage regulation and required permanent magnet volume compared to the initial design. In addition, the calculation of the voltage Total Harmonic Distortion (THD) is presented and the optimum skew angle for the optimum generator is computed to reduce the voltage THD. [ABSTRACT FROM AUTHOR]

The paper describes a method of scouring sheep wool using ultrasound. The inspiration to start work on the use of ultrasound in the process of scouring sheep wool was positive results that had already been achieved for alpaca wool. Due to the fact that sheep wool has many more impurites than alpaca wool, the scouring process is divided into two stages. The first involves the removal of faeces from the wool, which may be up to about 35% of the impurities of sheep wool, while the second stage involves the scouring cycle, wherein the remaining impurities are removed. The ultrasonic scouring process uses domestic merino wool heavily clad, particularly, by faeces. In this study, detergent solutions, alkali soap and sodium carbonate were used. The scouring of wool was carried out with a special apparatus equipped with an ultrasonic generator, at a frequency of 40 kHz. To determine the optimal conditions for scouring sheep wool that could affect the amount of impurities removed, the following parameters were examined: the effect of the scouring time, the concentration of detergents, and the scouring bath ratio. The study resulted in achieving optimal scouring parameters that ensured a satisfactory level of the removal of wool impurities. [ABSTRACT FROM AUTHOR]

This study proposes a special topology of transvers flux permanent magnet generator, which benefits from low Permanent Magnet (PM) costs due to use of cheap Ferrite PMs. In this structure, only one PM per phase is used to ensure easy manufacturing. Despite the above-mentioned advantages of the topology, it is subject to some disadvantages such as unbalanced voltage, high demagnetization risk of the PM, and high cogging torque. Aiming to solve these problems and maintaining the advantages of the topology, a new structure is proposed. The stator of this structure contains two series connected coils that eliminate all the even-order harmonics and balance the voltage waveform. This trick reduces the armature reaction as well as demagnetization of the PMs significantly. Moreover, the rotor teeth of the proposed structure are skewed, causing a significant reduction in cogging torque. The output results of the proposed structure are compared with those of the original one in terms of harmonic components, cogging torque profile, and PM demagnetisation. [ABSTRACT FROM AUTHOR]

Steve Nation has written a beautiful Preface to the Edition and Joni Carley (who first described "spiritual commons" to me), has written the Keynote. To do this work we need ways to tap our spiritual commons, human capacities for insight and awareness, resilience and creativity. The sound of the rising tide is heard clearly The miracle happens A beautiful child appears in the heart of a lotus flower One single drop of this compassionate water Is enough to bring back the refreshing spring to our mountains and rivers. [Extracted from the article]

The control of the novel five-dimensional hidden attractors hyperchaotic system is investigated. We suggest an approach to change the model of its hyperchaotic behavior to an unpredictable trivial fixed point employing the stability principle. We are also researching the synchronization of the same system, focusing on the stability theory. Numerical simulations show that effective control and synchronization results are obtained with the control method. [ABSTRACT FROM AUTHOR]

Poincaré surface of section is an important tool in the dynamical system which allow us to imagine and understand the numerical solution behavior of the system. Hide's couple dynamo model is rich and worth to study. In this paper, we apply the Poincaré surface of section in three cases periodic orbit motion, regular motion and chaos motion. [ABSTRACT FROM AUTHOR]

The analysis of thermoacoustic engines and the equations that describe the internal physical phenomena are far from simple. Previous studies on energetic characterisation of thermoacoustic engines are based only on the determination of the active acoustic power flow distribution. In this paper, another variable, known as the reactive acoustic power, is additionally estimated and studied. This article proposes a simple method which is based on the combination of both active and reactive acoustic power flow for the evaluation and optimisation of thermoacoustic Stirling engines. In addition the paper illustrates the method using a thermoacoustic Stirling engine demonstrator design which is able to fit three different feedback branches. The results show that the amount of reactive acoustic power supplied towards the core branch differs depending on the specifications of the selected feedback branch. Besides, the amount of reactive acoustic power distributed towards the core branch is a good indicator of the grade of traveling-wave phasing. An improvement of 16.4% in the active acoustic power towards the extraction branch is achieved and besides, the amplification of the active acoustic power through the core branch has increased by 12%. The method can serve as an effective tool to study and optimise thermoacoustic devices. [ABSTRACT FROM AUTHOR]

This paper proposes the implementation of an automatic system for starting a generator to supply consumers affected by the lack of supply voltage for a long time. The system has the role of supplying electricity to some consumers in case of interruption of the main power supply and switching to power supply from a secondary energy source (electric generator on gasoline or diesel engine). The concept of this automatic starting system is a stable one that can be easily adapted to existing electric generators on the market, with high flexibility, and at a low cost. [ABSTRACT FROM AUTHOR]

This paper presents the preliminary design of an airborne micro-wind turbine system. The blades are designed using a Joukowsky airfoil and the simulation of the wind turbine is made with the help of QBlade software. An electrical generator is designed and simulated with JMAG finite element method software. The results are showing good premises in terms of total mass and efficiency of power conversion. [ABSTRACT FROM AUTHOR]

• Power System Stabilizer (PSS) is designed for a modified Heffron-Phillips model which is developed by taking transformer secondary bus voltage at generator side as reference, instead of infinite bus voltage. • Particle Swarm Optimization (PSO) algorithm is used to tune the parameters of PSS and gain settings of the PID controller. • Robustness of the proposed technique is tested by taking several operating conditions under two typical disturbance conditions. The efficacy of the proposed technique is demonstrated with Eigen value analysis. This paper presents a novel method for designing robust Power System Stabilizer (PSS) using Particle Swarm Optimization (PSO) technique to improve the dynamic stability of the power system. Modified Heffron-Phillip's model is developed by considering the generator side transformer voltage as the reference instead of considering the infinite bus voltage as the reference to reduce the complexity and computational time. Using this MHP model, a power system stabilizer called Modified Power System Stabilizer (MPSS) is developed and integrated with P-I-D controller using PSO (PSO-P-I-D-MPSS) on a Single Machine Infinite Bus System. PSO algorithm is used to determine the gain settings of the P-I-D-MPSS. The developed PSO-P-I-D-MPSS is simple to implement and will be a better alternative to the conventional or evolutionary based PSSs. The efficacy of the proposed PSO-P-I-D-MPSS is validated by the application of proposed stabilizer to a benchmark system for several operating conditions under various disturbances. The results clearly show that the proposed stabilizer improves the dynamic stability of the power system under wide range of operating conditions. [ABSTRACT FROM AUTHOR]

• Online operating guidelines find the maximum net electrical energy. • Multi-linear model for variable-frequency fans was built. • The cooling capability index was used as a clustering index for the multi-linear model. • The online operating guidelines were demonstrated in this paper. • Two cases of the plant test based on the online operating guidelines were presented. Guidelines for optimal operation strategy of cooling water temperature are presented to find the maximum net electrical energy of a cogeneration system for turbine generators (TGs) and cooling towers (CTs). In this study, a real cogeneration plant in Taiwan, consisting of variable-frequency drive fan-based CTs and a generator, was chosen as a case study. Statistical linear models were used to build TGs and CTs. A multi-linear model was established to approach a nonlinear system in the cooling tower using a physically meaningful index, the cooling capability index, as an indicator of data clustering. The results showed that the cooling capability index was a good clustering index for the CTs. The cooling tower multi-linear model regressed by the clustering data performed well in predicting the cooling water outlet temperature. The simulated case verified that the online operating guidelines were consistent with real plant data and that it has the ability to find the optimal cooling water temperature. Two cases of plant test prove that the online operating guidelines can assist operators in operating cooling water temperature to the maximum net electrical energy. [ABSTRACT FROM AUTHOR]

Regulatory energy tariff revision planning conducted by the Brazilian regulatory agency ANEEL is based on the electric power company's accrued costs during the previous tariff revision cycle and the gain in productivity seen during this same period. However, this planning considers purely deterministic variables, which in practice are known for presenting a certain degree of uncertainty. This article uses the TAROT (optimized tariff economic model) socioeconomic model to simulate the tariff revision process of a regulated electric power company and considers a selection of important stochastic variables for the revision process, such as consumer energy consumption, the purchased energy cost from the generator and commercial energy losses. Therefore, a risk study will be conducted to present a methodology for calculating and determining the regulatory tariff of companies under risk conditions, which is designed to assist ANEEL in regulating the electric power sector. [ABSTRACT FROM AUTHOR]

Abstract This paper explores electricity planning strategies in South Sudan under future conflict uncertainty. A stochastic energy system optimization model that explicitly considers the possibility of armed conflict leading to electric power generator damage is presented. Strategies that hedge against future conflict have the greatest economic value in moderate conflict-related damage scenarios by avoiding expensive near-term investments in infrastructure that may be subsequently damaged. Model results show that solar photovoltaics can play a critical role in South Sudan's future electric power system. In addition to mitigating greenhouse gas emissions and increasing access to electricity, this analysis suggests that solar can be used to hedge against economic losses incurred by conflict. While this analysis focuses on South Sudan, the analytical framework can be applied to other conflict-prone countries. Highlights • We explore South Sudan electricity planning strategies under conflict uncertainty. • Stochastic optimization is used to produce a near-term hedging strategy. • Analysis considers key uncertainties that could affect planning outcomes. • Conflict hedging has the least economic value under the most extreme scenarios. • Solar photovoltaics may be an attractive hedge against future conflict. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive control analysis is presented, with emphasis on regulating the terminal voltage of a photovoltaic generator, interfaced with a current mode controlled buck DC-DC converter, which is, in turn terminated by a battery. The combined generator-convertor-load system possesses nonlinear behaviour, and is subject to environmental conditions, thus causing the control task complicated. Additionally, analyses of small signal equations reveal a possible unstable condition. Hence, a new method of designing a controller for worst-case scenario is presented. Additionally, results of implementing a typical linear controller (PI), which can be designed only in reference to a single nominal operation point, revealing a varied responses. Simulation and results of mathematical analysis are presented to verify the proposed method. [ABSTRACT FROM AUTHOR]

Utilization of waste material for value-added applications is a sustainable approach towards reduction of global waste. Herein, the waste rust iron is transformed into useful Fe 2 O 3 nanoparticles (FNPs). Here for the first time, FNPs were uniquely utilized in multiple applications, including resistive switching (RS), tribo and piezo-electric nano-generators, magnetic hyperthermia, and toxic dyes adsorption from water. The RS characteristics of the Ag/FNPs/ITO device emphasized bipolar switching with excellent cyclic stability, endurance, and memory retention. Afterward, the FNPs based tribo and piezo-electric nanogenerator device demonstrated greater instantaneous power (5200 µW) at 10 MΩ, surpassing previously reported inorganic or garbage materials. Furthermore, the pertinency of FNPs was explored for biomedical application by induction heating studies for magnetic fluid hyperthermia (MFH). MFH revealed an increase in temperature of 14.9 °C and 23.4 °C for 5 mg and 10 mg FNPs ferrofluid, respectively, thus indicating the potential of FNPs for possible cancer treatment with biocompatibility suggestions. Finally, the adsorption study reveals that the FNPs are a promising candidate for the adsorption of safranin M.S., methylene blue, malachite green, and lemon yellow powder, (77, 78, 59, and 56 mg/g, respectively). We believe that our current study will result in a significant impact to reduce the future burden of global waste and thus encourage its utilization for value-added applications. [Display omitted] • Waste rust iron converted to Fe 2 O 3 nanoparticles (FNP) via. grinding and annealing. • The FNPs first time utilized for four different applications. • Resistive switching of the FNPs emphasized excellent performance. • Tribo/piezo-electric nanogenerator showed greater instantaneous power (5200 µW). • FNPs hold application in magnetic hyperthermia and adsorption of toxic dyes. [ABSTRACT FROM AUTHOR]

The electrolysis process of water with electrolyte (NaOH) produces oxy-hydrogen (HHO) gas that can be used as an energy source to solve the shortage problem of fossil fuel and reduces the environmental pollution. In this study, HHO dry cell generator was designed, fabricated and tested experimentally to investigate its performance. The hybrid internal combustion engines using HHO is considered one of the most important studied applications. The engine performance and gas emission are investigated for two different engines; 150CC old engine with carburetor and 1300CC new engine with Electronic Control Unit (ECU). The results recorded the consumption of the fuel is reduced by 14.8 % for 150CC engine and 16.3 % for 1300CC engine. HHO gas reduced the emission gases by 33 % and 24.5 % reduction in CO and 27.4 % and 21 % reduction in HC for 150CC and 1300CC engines respectively. [ABSTRACT FROM AUTHOR]

Abstract One of the main interested subjects in electric power systems is the integration of electric vehicles to the existing power network as well as the influence of this integration with the other types of renewable sources connected to the multi area power system networks. Load Frequency Control (LFC) are used to regulate and control the output frequency signal of the electric generated power within an area in response to changes in system loads and power in tie line changed with other area. This paper presents a new design of various types of load frequency PI controllers based on different types of Artificial Intelligent (AI) optimization techniques such as Fuzzy logic, FOPID tuned by fuzzy and Model Predictive Control (MPC) for a four area power system. The performance of the controller under study shows an enhancement in the frequency deviation signal as well as the peak overshoot and Settling time for the frequency output signal. The performance of the proposed scheme is validated using MATLAB/SIMULINK tools. [ABSTRACT FROM AUTHOR]

Abstract Identification of transient stability state in real-time and maintaining stability through preventive control technology are challenging tasks for a large power system while integrating deregulation constraints. Widely employment of the phasor measurement units (PMUs) in a power system and development of wide area management systems (WAMS) give relaxation to monitoring, measurement and control hurdles. This paper focuses on two research objectives; the first is transient stability assessment (TSA) and second is selection of the appropriate member for the control operation in unstable operating scenario. A model based on the artificial machine learning and PMU data is constructed for achieving both the objectives. This model works through prompt TSA status with radial basis function neural network (RBFNN) and validates it with PMU data to determine the criticality level of the generators. To reduce the complexity of the model a transient stability index (TSI) is proposed in this paper. A RBFNN is used to determine the transient stability aspects like stability status of system, coherent group and criticality rank of generator and preventive control action, following a large perturbation. PMUs measure post-fault rotor angle values and these are used as input for training RBFNN. The proposed approach is demonstrated on the IEEE 10-generator 39-bus, 16-generator 68-bus and 50-generator 145-bus test power systems successfully and the effectiveness of the approaches is discussed. Graphical abstract Highlights • A method is proposed to overcome the first swing instability detection problem. • A novel real time transient stability assessment through RBFNN. • Proposal of Transient Severity Index, to anticipate the criticality of generators. [ABSTRACT FROM AUTHOR]

This paper presents a broadband vibration energy harvester (VEH) which consists of a monostable Duffing oscillator connected to an electromagnetic generator via a mechanical motion rectifier. The mechanical motion rectifier converts the bidirectional vibratory motion of the oscillator induced by ambient environment vibrations into unidirectional rotation of the generator and causes the harvester to periodically switch between a large- and small-inertia system, resulting in nonlinearity in inertia. By means of analytical and numerical methods, this inertia nonlinearity is shown to have two advantages. First, it allows for more stiffness nonlinearity without inducing nonuniqueness of energy branches and enhances bandwidths of energy harvesting. The effect of mitigating nonuniqueness of energy branches occurs to steady-state and transient responses of the harvester and is experimentally verified by a prototype. The experimental results show a nearly 50% increase in the half power bandwidth via mechanical motion rectification (MMR). Second, it enlarges the basin of attraction of the high-energy branch when multiple energy branches are present. A numerical example shows that a more than 50% increase in the basin area can be achieved via MMR. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The impact of PENG and TENG to the field of energy harvesting is reported. • The trend of publications in the area of NGs is investigated and its correlation with S-shaped history is shown. • The trend of citations for PENGs and TENGs is presented. • The perspective of the research in this field is discussed. Abstract Piezoelectric and triboelectric nanogenerators are the two recently developed technologies for effective harvesting of ambient mechanical energy for self-powered systems. The work herein briefly reports the trends and impacts of research based on piezoelectric and triboelectric nanogenerators. For the first time, a statistical study of publication trends in piezo- and triboelectric nanogenerators is used to investigate the current state of the research. We investigate the status of the research in these fields, based on their S-shaped history, as a description of their growth in size over time, considering the number of citations and published papers that use these two novel technologies. A brief discussion of the outlook for these technologies and their potential impact on everyday life is presented, particularly in the development of future 'smart' cities. [ABSTRACT FROM AUTHOR]

Making use of the steam heat storage in thermal generators enables them to operate in a "fast mode" to ramp up or down faster than regular, so as to better catch up with the fluctuations of wind power to improve system wind utilization. In such fast mode, generators have output dependent ramp rates and, distinguished from regular units, output and ramp rate dependent coal consumption costs. These fast generators cannot be properly described by using existing economic dispatch models, where generators usually have output dependent cost functions and constant ramp rate limits. This paper presents a new formulation and solution methodology of dynamic economic dispatch for wind-thermal power systems, to take into account ramping capabilities and costs of generators in their fast mode. In our model, the objective is to minimize a two-variable quadratic generator cost function depending on both output levels and ramp rates, and generator ramp rate limits are output dependent piece-wise linear functions. The model is solved by using existing quadratic programming methods, and is demonstrated by using numerical examples on the IEEE 30-bus system containing two 600MW thermal units with practical data. Results show that by using our model, unit ramping capabilities are better utilized in system dispatch to substantially save curtailed wind energy, and total generator costs are reduced. [ABSTRACT FROM AUTHOR]

A variable electromotive-force generator (VEG), which is a modified generator with an adjustable overlap between the rotor and the stator, is proposed to expand the operational range of a regular generator through a simple and robust active control strategy. It has a broad range of applications in hybrid vehicles, wind turbines, water turbines, and similar technologies. A mathematical model of the VEG is developed, and a novel prototype is designed and fabricated. The performance of the VEG with an active control system, which adjusts the overlap ratio based on the desired output power at different rotor speeds for a specific application, is theoretically and experimentally studied. The results show that reducing the overlap between the rotor and the stator of the generator results in reduced torque loss of the generator and an increased rotational speed of the generator rotor. A VEG can improve the fuel efficiency of hybrid vehicles; it can also expand operational ranges of wind turbines and water turbines and harness more power. [ABSTRACT FROM AUTHOR]

This paper presents a test bench, designed for testing the functionality and reliability of a microcontroller based device meant to protect the consumers connected to the power grid. By means of this test system, the testing device is repeatedly applied to overvoltages, overloads, electric ground leakages and an electric arc. The test system checks up the load disconnection, as well as its automated reconnection, and in the end it generates a test report. [ABSTRACT FROM AUTHOR]

Zinc oxide microrods were synthesized by aqueous chemical growth using zinc nitrate and zinc acetate solutions without seed layer. Rod length of around 10 µm was obtained after 5 hr at 95°C. Solution replenishment led to a better alignment normal to the substrate; however, only zinc acetate solution resulted in bigger rods, reaching about 12 µm in length and 5 µm in diameter. X-ray diffraction revealed a pure hexagonal wurtzite structure with high crystallographic texture. Raman spectroscopy showed no evidence of lattice stress. The ZnO microrod arrays were used to fabricate piezoelectric generators, and the largest output was obtained from the generator with the higher density of rods. The use of a piezoelectric polymer in the generators led to an improved performance of at least 200% compared to reports that used a dielectric polymer. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The primary objective of the proposed paper is to conduct a techno-economic study of an off-grid PV/Biomass hybrid system. We employed various optimization techniques. This included the Flower Pollination Algorithm (FPA), the Harmony Search (HS) algorithm, the Artificial Bee Colony (ABC) Algorithm and the Firefly Algorithm (FA). The ultimate objective was to determine an optimal solution for the sizing problem. In this context, the proposed procedure optimally selects the capacity of three types of generators, namely solar PV, biomass, and battery banks. The data for this study was collected from Monshaet Taher village, located in Egypt. To improve the performance, we restrained the selection between these generators to be based on minimizing the Net Present Cost (NPC) for a specified Loss of Power Supply Probability (LPSP) and Percentage of the excess energy (EXC). Three different battery technologies, including Flooded lead-acid (FLA), Lithium Ferro Phosphate (LFP) and Nickel Iron (Ni-Fe) have been considered in this study. The simulation results show that the Firefly Algorithm has the minimum execution time and best performance among the other algorithms, it also shows that the optimal configuration is obtained for a system comprising of 24 PV panels, 4 biomass power systems, and 298 Ni-Fe batteries. [ABSTRACT FROM AUTHOR]

PhotoVoltaic (PV) microgeneration ( μG ) located close to the end-users is gradually increasing and is expected to increase more in the future. However, a high μG penetration level may cause overvoltage issues in the Low Voltage (LV) distribution grid. On the other hand, these μG PV generators are usually placed in residential houses, composed by nonlinear loads that generate harmonics. The use of the harmonics compensation capabilities provided by modern PV systems can be an added value, as this function improves the voltage profile and reduces losses on the LV distribution network. This paper proposes an additional contribution to the subject by studying the impact of the use of PV systems harmonics compensation features to mitigate the harmonics produced by residential nonlinear loads. The assessment tool is a suitable algorithm created to compute an unbalanced three-phase power flow in the presence of harmonics. This is based on the Common Object Model (COM) interface of two software tools, MATLAB and OpenDSS. Three case-studies are proposed: harmonic compensation disabled, harmonic compensation enabled and reactive power control. The last one is introduced for comparison purposes. The assessment is made for a typical summer day, on a highly unbalanced test radial LV distribution network with high μG penetration and harmonic pollution. The obtained results allow the conclusion that the PV system harmonic compensation capability is able to attenuate the harmonics, therefore improving the voltage profile, and reducing the power losses and voltage drop on the LV distribution network. [ABSTRACT FROM AUTHOR]

Droop control is the conventional way to share the demand power among the generators in a microgrid. Analyzing this control method shows that it has poor performance in reactive power sharing. Generated reactive power of each microsource depends on the active load demand. In this paper, a control method is proposed to improve the reactive power sharing performance. It is indicated that higher reactive power droop gains make the generated reactive power to be less influenced from the changes in active load. However, high droop gains can lead the system to instability. Hence considering eigenvalue analysis of the microgrid, a new auxiliary controller is proposed to damp the oscillations caused by high droop gains. In the new method, there is not the need for monitoring the grid impedance to tune the controllers. To verify the proposed method, load step is applied to a test microgrid and the results are shown. In the new method, total generated reactive power is reduced in comparison to the conventional droop controller and the system stability is maintained. [ABSTRACT FROM AUTHOR]

In this paper, a sequence component extractor based on a recursive least square is used in a wind generation application. The deadbeat controller computes the rotor voltage to be applied to the doubly fed induction generator during the voltage sag condition. The control is designed by the discretized rotor equations and makes use of the stator field-oriented control technique. The SCE-RLS calculates each sequence component of stator voltages or currents that allow the right position of the mentioned vectors. Comparisons made by MATLAB/Simulink and by experimental tests corroborate the advantageous of the proposed recursive least squares extractor over the one based on the Secondary General Order Integrator. [ABSTRACT FROM AUTHOR]

This paper proposes an advanced strategy to synchronize the wind-driven Brushless Doubly-Fed Reluctance Generator (BDFRG) to the grid-side terminals. The proposed strategy depends mainly upon determining the electrical angle of the grid voltage, θ v and using the same transformation matrix of both the power winding and grid sides to ensure that the generated power-winding voltage has the same phase-sequence of the grid-side voltage. On the other hand, the paper proposes a vector-control (power-winding flux orientation) technique for maximum wind-power extraction under two schemes summarized as; unity power-factor operation and minimum converter-current. Moreover, a soft-starting method is suggested to avoid the employed converter over-current. The first control scheme is achieved by adjusting the command power-winding reactive power at zero for a unity power-factor operation. However, the second scheme depends on setting the command d-axis control-winding current at zero to maximize the ratio of the generator electromagnetic-torque per the converter current. This enables the system to get a certain command torque under minimum converter current. A sample of the obtained simulation and experimental results is presented to check the effectiveness of the proposed control strategies. [ABSTRACT FROM AUTHOR]

During grid fault, transmission lines reach its thermal limit and lose its capability to transfer. If this fault current enters generator terminals, it will lead to dip in stator voltage and consequently produces torque and real power oscillations. This further affects in the form of internal heat in rotor windings and finally damages the generator. A new control strategy is proposed to limit fault current using dual STATCOM, which will damp power oscillations and mitigate the voltage dip due to a severe symmetrical fault. It is achieved by diverting the fault current to the capacitor using the dual-STATCOM controller. It is best suitable to maintain power system stability with uninterrupted power supply, effective power transfer capability and rapid reactive power support and to damp inter-area oscillations. The effectiveness of SG and DFIG due to the transmission line short circuit symmetrical fault was studied. [ABSTRACT FROM AUTHOR]

The specific characteristics of a diesel engine with pneumatic fuel atomization are described in the article. Possible variants of embodiments of fuel pneumatic atomization in diesel engines are suggested. To obtain compressed air for fuel atomization, the authors considered to use a compressor driven by electrical power received from high frequency electric generator, which is located between the gas turbine and the charge air, the blower is powered by exhaust gas energy is the most appropriate. The results of comparative experiments on diesel 1CHN15,0/20,5 in original and experimental configuration with pneumatic atomization of fuel are provided. These materials presented an obvious advantage of the pneumatic atomization regarding the emission of hazardous air pollutant, indicators workflow and features of the combustion process flow; particularly the ignition delay period has decreased almost by 80%. The pressure ratio was significantly reduced and the degree of pre-expansion increased dramatically. [ABSTRACT FROM AUTHOR]

The article presents a method of accelerated tests (ATs) of turbine blades in gas turbine power plants (GTPPs) (aircraft gas turbine engines, gas turbine drives of compressors and electric generators, etc.). It is known that the reliability and service life of GTPPs are mainly determined by the elements of the hot section (the moving blades and nozzle vanes, turbine disks), they are exposed to multicycle loads, repeated static (low-cycle) loads and long-term static loads, as well as to a high temperature gas environment. Gas corrosion is one of the serious types of blade damage which causes a decrease in reliability and efficiency of turbines in GTPPs. The existing methods of ATs of turbine blades which are performed on individual test benches do not reproduce a complete picture of their damage rate, while the ATs of GTPPs reproduce the damage rate of blades caused only by multicycle loads, low-cycle loads and long-term static loads, but they do not reproduce the damage rate caused by the gas environment due to an insignificant duration (as compared to the service life) of the exposure of a blade to a gas environment. Two options of performing blade ATs are examined. The first option consists in testing a blade separately from the GTPP. The blade is subjected to block loading which consists of individual blocks. Each block reproduces in a successive order the damage rate caused by multicycle loads, low-cycle loads and long-term static loads and the damage rate caused by the gas environment. The second option consists in ATs of a GTPP fitted with blades which have already become outdated in terms of corrosion damage rate. The examined methods of blade ATs enable to increase the reliability of the integrated assessment of the robustness of GTPP blades operated under multicomponent loading conditions. [ABSTRACT FROM AUTHOR]

Solar collector is an important part of solar cooling system, which provides heat source for the generator. With the help of Aspen Plus software, the three working fluid systems of LiBr/H2O, NH3/H2O, and R134a/DMF are established. And this paper analyzes the corresponding collector type for the three systems.We find that When the condensing-temperature is 38℃and the range of dilute solution concentration is 54%~56%, the LiBr/H2O system can choose low solar thermal collector. When the condensing-temperature is up to 42℃, High/Medium solar thermal collector is appropriate for LiBr/H2O. NH3/H2O system can only choose High/Medium solar thermal collector. And R134a/DMF system can choose low solar thermal collector when deflated range is between 0.17 to 0.3; when deflated range is higher than 0.3, R134a/DMF system can choose high solar thermal collector. [ABSTRACT FROM AUTHOR]

A rotational energy harvesting system comprises a sprung mass coupled to an electrical generator through a motion transmission system such as a ball screw. In this paper, the operational bandwidth of a rotational energy harvester is expanded by varying its moment of inertia and load resistance of the generator. It is shown that the resulting tuneable device produces significantly higher amounts of harvested power. In addition to mass and stiffness, the natural frequency of a rotational device is defined by its moment of inertia, an additional design parameter that enables implementing the approach presented here. This parameter also determines the apparent mass (inertance) of the device, an important factor that allows a small additional mass to increase the apparent mass hugely and hence increase the overall power density of the harvester. It is shown that the system with variable load resistance shows a good performance at frequencies around the natural frequency of the device whereas away from resonance frequencies the system with variable moment of inertia produces more power. The approach described in this paper is a first step in the direction of having an autonomous energy harvester with a wide operational bandwidth. One of the advantages of the presented method is that, unlike some other methods, changing the adjustable parameters (i.e., moment of inertia and load resistance) can be conducted intermittently. In other words, this approach only consumes power during the tuning operations and does not use energy once the harvester is tuned at its optimum conditions. These tuneable rotational systems should be used where the excitation frequency varies slowly (e.g., in marine environment) as any sudden changes in frequency would result in an instantaneous change in the apparent mass and the device may even stall. To implement the device effectively, some kind of predictive control may need to be used that can detect frequency variations fast enough for the inertia to change in a timely manner. This aspect that is outside the scope of this paper is currently under investigation. [ABSTRACT FROM AUTHOR]