Wind Energy Efficiency Research Articles

Enhanced Direct Power Control Strategy of a DFIG-Based Wind Energy Conversion System Operating Under Random Conditions

The main objective of this paper is the performances analysis of an Enhanced Direct Power Control (EDPC), applied to Doubly Fed Induction Generator (DFIG) driven by variable speed Wind Turbine (WT). This control strategy uses hysteresis regulators and switching table for active and reactive powers control. These latter are estimated using rotor currents and grid voltages instead of a traditional measurement of stator currents. In addition, the EDPC switching table is based on the position of the rotor flux instead of the stator flux in order to have better regulation accuracy because the rotor voltage vector directly influences the rotor flux and has a proportional relationship with the active and reactive powers. All the operating modes (sub-synchronous, super-synchronous, synchronous and over-speed) of the variable speed WT-DFIG system and the possibility of local reactive power compensation are reported and discussed in this paper. Depending on the operating zone of the WT, Maximum Power Point Tracking (MPPT) technique and pitch angle control are considered to optimize the wind energy efficiency. The validation of the proposed EDPC strategy has been performed through simulation tests under MATALB/Simulink, the obtained results show robustness and good performances with low THD of the generated currents.

Auto Disturbance Rejection Control Strategy of Wind Turbine Permanent Magnet Direct Drive Individual Variable Pitch System Under Load Excitation

The wind turbine blades have complex stress states, and the load has the characteristics of time-varying and uncertainty. Aiming at the interference problem caused by complex and variable load characteristics to the individual pitch control system, combined with the variable-pitch load characteristics, based on the permanent magnet synchronous motor (PMSM) vector control strategy and LADRC (Auto Disturbance Rejection Speed Controller), an individual pitch speed controller is designed. Linear expansion state observer is built. The control algorithm is deduced and the relationship between each control parameter is analyzed to improve the anti-interference ability of the system to the abrupt load of the pitch. On this basis, the system position tracking controller is built. Finally, a vector control simulation model was built based on MATLB/Simulink, and a speed control simulation was carried out. The simulation results show that LADRC has a strong anti-load disturbance capability, and has better anti-disturbance resistance than PID speed control, and the position controller based on this has a better position tracking effect. At the same time, the effectiveness of the designed independent pitch speed controller has also been verified through experiments. It is of great significance for improving the conversion efficiency of wind energy.

Emergy and Sustainability Ternary Diagrams of Energy Systems: Application to Solar Updraft Tower

To facilitate sustainable energy development, one has to understand the limited availability of nonrenewable energy resources, and the ability of the earth to renew or recover. Emergy is an instrument that measures environmental loading, ecological economics, and regional sustainable development. In this study, emergy indicators are calculated to investigate the sustainability of solar updraft tower (SUT). SUT produces energy from the hot air, utilizing a combination of a solar collector, central tower, and air turbines. The results demonstrate that the sustainability of SUT grew as the size of the plant increased. Further, emergetic ternary diagrams are drawn to facilitate the comparison between SUT and various technologies. The resources-use efficiency of wind energy and SUT, 200 MW is found to be the lowest among all energy technologies presented in this research. Scenario analysis is performed to explore the future optimization directions. The results demonstrate that the development direction of SUT systems should mainly focus on reducing the materials demanded by the manufacturing and construction of its solar collectors. This study aims to demonstrate the value of emergy as a powerful instrument for drawing long-term sustainable strategies in energy markets for a greener tomorrow.

Two-Stage Optimization Model for Two-Side Daily Reserve Capacity of a Power System Considering Demand Response and Wind Power Consumption

Today, wind power is becoming an important energy source for the future development of electric energy due to its clean and environmentally friendly characteristics. However, due to the uncertainty of incoming wind, the utilization efficiency of wind energy is extremely low, which means the problem of wind curtailment becomes more and more serious. To solve the issue of wind power large-scale consumption, a two-stage stochastic optimization model is established in this paper. Different from other research frameworks, a novel two-side reserve capacity mechanism, which simultaneously takes into account supply side and demand side, is designed to ensure the stable consumption of wind power in the real-time market stage. Specifically, the reserve capacity of thermal power units is considered on the supply side, and the demand response is introduced as the reserve capacity on the demand side. At the same time, the compensation mechanism of reserve capacity is introduced to encourage generation companies (GENCOs) to actively participate in the power balance process of the real-time market. In terms of solution method, compared with the traditional k-means clustering method, this paper uses the K-means classification based on numerical weather prediction (K-means-NWP) scenario clustering method to better describe the fluctuation of wind power output. Finally, an example simulation is conducted to analyze the influence of reserve capacity compensation mechanism and system parameters on wind power consumption results. The results demonstrate that with the introduction of reserve capacity compensation mechanism, the wind curtailment quantity of the power system has a significant reduction. Besides, the income of GENCOs is gradually increasing, which motivates their enthusiasm to provide reserve capacity. Furthermore, the reserve capacity mechanism designed in this paper promotes the consumption of wind power and the sustainable development of renewable energy.

Power dispatching tracking control of wind turbine considering maximum and limited power generation below rated wind speed

Wind turbines should respond to power dispatching of power grid at all times. According to this demand, this paper puts forward a set of feasible power control strategies below rated wind speed. Firstly, the operation state of wind turbine is divided into two working modes: maximum power generation and wind power curtailment generation. Different control strategies are adopted in different working conditions. Under the mode of maximum power generation, the model predictive control (MPC) algorithm is used to give a torque compensation gain. The MPC controller not only improves the utilization efficiency of wind energy, but also reduces the mechanical load. Under the mode of wind curtailment, a hybrid tracking control strategy of giving priority to torque control than pitch regulation is adopted. It reduces the frequency and amplitude of the pitch mechanism greatly. By comparing the simulation results under various wind speeds, it is found that the proposed power control strategy can adapt to different power dispatching scenes, and can respond to power dispatching with greater performance. It is very significant for the improvement of wind power generation system.

Measurement and Analysis of the Development and Utilization Efficiency of Wind Energy in Jilin Province

On the basis of relevant literature review on energy efficiency, this paper firstly analyzed the overall situation of wind energy development and utilization in Jilin Province, then determined the input-output indicators of wind energy development and utilization according to the indicator-selection principles, and then used DEA analysis method to analyze the data of Jilin Province from 2005 to 2017. The research result shows that the scale of wind energy development in Jilin Province has been relatively appropriate since 2005, and its comprehensive efficiency value is mainly affected by pure technical efficiency. Therefore, it is necessary to strengthen the management of wind energy development in Jilin Province. But on the contrary, the comprehensive efficiency of wind energy utilization in Jilin Province is mainly affected by scale efficiency. Because the scale efficiency value has been decreasing year by year, the control of input scale of wind energy utilization should be strengthened, so as to further enhance the contribution rate of wind energy products to the national economy.

Forecasting Short-Term Wind Speed Based on IEWT-LSSVM Model Optimized by Bird Swarm Algorithm

Accurate wind speed prediction can improve the utilization efficiency of wind energy effectively. However, the original time series signals of wind speed present nonlinear or non-stationary characteristics, which make wind speed forecasting very difficult. A new pre-processing method of wind speed signal, named improved empirical wavelet transform (IEWT), is proposed in this paper, which is inspired by the spectrum segmentation theory of EWT. Then, a novel hybrid model combining IEWT and least square support vector machine (LSSVM) is put forward to predict short-term wind speed. In order to achieve better prediction results, the parameters are jointly optimized through bird swarm algorithm (BSA) in this model. The prediction performance of the established hybrid model is tested with practical wind speed signal of four seasons from a wind farm situated in Zhejiang, China. The experimental results indicate that the presented hybrid forecasting model can effectively follow the change of wind speed, which exhibits more superior predicting performance than other popular models.

A novel wind speed forecasting system based on hybrid data preprocessing and multi-objective optimization

Wind speed forecasting is an important task in large-scale wind power integration that can eliminate the harmful influence caused by its inherent intermittence and volatility. To achieve high-precision wind speed forecasting, hybrid systems that combine artificial intelligence algorithms have been widely employed. However, in most previous studies, in the learning process of wind speed forecasting using hybrid systems, two open challenges arise: it is hard to ensure that the main features of wind speed data can be completely extracted using simple data preprocessing, and attempting to enhance only the accuracy while ignoring the stability is insufficient in practical applications. In this study, a novel hybrid forecasting system is successfully proposed to solve the abovementioned issues, with the following novel contributions: (i) a new data preprocessing algorithm is developed based on the proposed hybrid data preprocessing strategy, which combines the advantages of each meritorious component and appears to be a promising data preprocessing method; and (ii) the Elman neural network model, improved by our newly proposed multi-objective satin bowerbird optimizer algorithm, is successfully developed, which provides a great contribution to the excellent forecasting performance in terms of accuracy and stability. To verify the forecasting effectiveness of the system, several forecasting cases based on eight wind speed datasets are presented in this study, and the results reveal that the proposed system has better forecasting accuracy and stability than other benchmark models and can be used to enhance the utilization efficiency of wind energy as well as other fields.

Maximum efficiency of wind energy using novel Dynamic Voltage Restorer for DFIG based Wind Turbine

Fault-tolerable capability of Doubly Fed Induction Generator (DFIG) against disturbance occurrence is recognized as Fault Ride-Through (FRT). With quick and accurate compensation potentiality of Dynamic Voltage Restorer (DVR) to retrieve the nominal PCC voltage, DFIG can safely follow its normal operation in the power system. Multi-Level Inverter (MLI) as the main part of DVR with unique responsibility of synthesizing the staircase sinusoidal voltage ascertains the performance and flexibility of DVR. In this paper a novel asymmetrical MLI structure based on Level Creator and H-bridge inverter is indwelt in DVR in order to providing the high quality voltage. To more augment the efficiency of DVR in dealing with FRT issue, it has been equipped with Brain Emotional Learning Based Intelligent Controller (BELBIC) based on Multi Objective Bees Algorithm (MOBA). So-called AMLI-BELBIC based DVR has been thoroughly appraised under different balanced and unbalanced voltage sags and swells so that FRT capability of DFIG to be appeared. To sum up, the relevant analytical expression along with the simulation results has transparently corroborated the performance of AMLI-BELBIC based DVR aimed to augment the FRT capability of DFIG.

Development of a Voltage Compensation Type Active SFCL and Its Application for Transient Performance Enhancement of a PMSG-Based Wind Turbine System

Considering the rapid development of high temperature superconducting (HTS) materials, superconducting power applications have attracted more and more attention in the power industry, particularly for electrical systems including renewable energy. This paper conducts experimental tests on a voltage compensation type active superconducting fault current limiter (SFCL) prototype and explores the SFCL’s application in a permanent-magnet synchronous generator- (PMSG-) based wind turbine system. The SFCL prototype is composed of a three-phase air-core superconducting transformer and a voltage source converter (VSC) integrated with supercapacitor energy storage. According to the commissioning test and the current-limiting test, the SFCL prototype can automatically suppress the fault current and offer a highly controlled compensation voltage in series with the 132 V electrical test system. To expand the application of the active SFCL in a 10 kW class PMSG-based wind turbine system, digital simulations under different fault cases are performed in MATLAB/Simulink. From the demonstrated simulation results, using the active SFCL can help to maintain the power balance, mitigate the voltage-current fluctuation, and improve the wind energy efficiency. The active SFCL can be regarded as a feasible solution to assist the PMSG-based wind turbine system to achieve low-voltage ride-through (LVRT) operation.

Design of multi-energy Helds coupling testing system of vertical axis wind power system

The conversion efficiency of wind energy is the focus of researches and concerns as one of the renewable energy. The present methods of enhancing the conversion efficiency are mostly improving the wind rotor structure, optimizing the generator parameters and energy storage controller and so on. Because the conversion process involves in energy conversion of multi-energy fields such as wind energy, mechanical energy and electrical energy, the coupling effect between them will influence the overall conversion efficiency. In this paper, using system integration analysis technology, a testing system based on multi-energy field coupling (MEFC) of vertical axis wind power system is proposed. When the maximum efficiency of wind rotor is satisfied, it can match to the generator function parameters according to the output performance of wind rotor. The voltage controller can transform the unstable electric power to the battery on the basis of optimizing the parameters such as charging times, charging voltage. Through the communication connection and regulation of the upper computer system (UCS), it can make the coupling parameters configure to an optimal state, and it improves the overall conversion efficiency. This method can test the whole wind turbine (WT) performance systematically and evaluate the design parameters effectively. It not only provides a testing method for system structure design and parameter optimization of wind rotor, generator and voltage controller, but also provides a new testing method for the whole performance optimization of vertical axis wind energy conversion system (WECS).

Greening offshore wind with the Smart Wind Chart evaluation tool

Abstract. The development of offshore wind farms (OWFs) and the establishment of marine protected areas (MPAs) comprise two main elements for the production of clean energy, and the simultaneous maintenance and protection of biodiversity in the Mediterranean and Black seas. Successful, efficient, and sustainable coupling of these two aspects presumes that the criteria for selecting suitable locations for the deployment of OWFs should not only include technical-engineering terms (e.g. high wind energy efficiency, bottom suitability, inland infrastructures) but also ecological–environmental considerations (e.g. the least possible impact on biodiversity, ecosystem functioning) and socio-economic aspects (e.g. effects on coastal and marine activities, development of marine spatial planning). In the context of the FP7 CoCoNet project, the integration between OWFs and MPAs is based on four main steps: (i) the identification of existing (networks of) MPAs focusing on the biodiversity distribution patterns and current legislation, (ii) the coupling of offshore wind potential within networks of MPAs, (iii) the evaluation of the knowledge gained up to date and the theoretical approaches at the two pilot sites of the Mediterranean and Black sea basins, and (iv) the development of the "Smart Wind Chart", a convenient and rational tool addressed to scientists and policy makers for the evaluation of maritime policy management schemes. The latter step comprises the core of this work.

Modeling, Simulation, Hardware Implementation of a Novel Variable Pitch Control for H-Type Vertical Axis Wind Turbine

Abstract It is well known that the fixed pitch vertical axis wind turbine (FP-VAWT) has some disadvantages such as the low start-up torque and inefficient output efficiency. In this paper, the variable pitch vertical axis wind turbine (VP-VAWT) is analyzed to improve the output characteristics of FP-VAWT by discussing the force of the six blade H type vertical axis wind turbine (VAWT) under the stationary and rotating conditions using built the H-type VAWT model. First, the force of single blade at variable pitch and fixed pitch is analyzed, respectively. Then, the resultant force of six blades at different pitch is gained. Finally, a variable pitch control method based on a six blade H type VP-VAWT is proposed, moreover, the technical analysis and simulation results validate that the variable pitch method can improve the start-up torque of VAWT, and increase the utilization efficiency of wind energy, and reduce the blade oscillation, as comparable with that of FP-VAWT.

Offshore wind farms in Southern Europe – Determining tourist preference and social acceptance

There is increasing consensus that resistance to the siting of wind power facilities cannot be explained by the NIMBY phenomenon alone or other localized environmental impacts. This deficiency is addressed by examining the determinants of tourist preferences for positioning of wind farms in the Mediterranean Sea. A principal component analysis is used to identify general attitudinal themes that act as covariates in a choice model. We demonstrate that the welfare economic impacts associated with spending holidays in the vicinity of an offshore wind farm do not merely depend on visibility effects, but equally on the individual's opinion of climate change, efficiency of wind energy and the substitutability of nuclear and fossil fuels with renewable power generating sources.

Numerical investigation on the exergetic performance of NREL airfoil families for wind turbine application

Increment of extracting wind energy efficiency via wind turbines substantially depends on a consummate understanding of the process of conversion of wind energy to useful work. In this study, the performances of three different National Renewable Energy Laboratory airfoil families are numerically investigated using a 2D incompressible unsteady computational fluid dynamics (CFD) solver and exergy analysis. The results indicate that the flow conditions possessing highest magnitudes of lift force do not obligatory represent the topmost exergetic efficiency; furthermore, it is concluded that the most exergetic effective flow condition can represent lowest drag to lift ratio. Dissipated exergy evaluation is demonstrated to assists defining how much of the inlet exergy would remain available in downstream. The results of an exergy analysis provide influential insights over different aspects of flow over airfoils and can be useful in wind engineering.

Research on Economic Operation Optimization of Electric System Including Wind Power Based on Interruptible Load

Apply interruptible load to include-wind-power electric system.Firstly, analyze a practical compensation mechanism for the interruptible load.Secondly,an economic optimization model is established considering both wind power and interruptible load.Finally,take an example to compare the impact exerted by the two dimensions on electric power system,the result shows that,by optimal use of interruptible load in include-wind-power electric system,not only enhanced the utilization efficiency of wind energy,but also greatly relieved congestion and maximized social benefits.

Research on Direct Torque Control of Doubly-Fed Generator Based on DSP Technology

Doubly-fed VSCF wind power generator has become the main machine because it can improve the efficiency of wind power and obtain the optimal energy output at rated wind speed. In the control of excitation on double fed generator,the technique of direct torque control become the mostly method.This paper adopts voltage space vectors subdivision technology of direct torque control technology that can improve the low frequency characteristic,and structure the experiment system based on DSP. The result indicated the project is feasiblIntroduction Wind power as a kind of green energy has attracted more and more attention. in recent years, wind power technology has made rapid development. Double-fed generator becoming the main type of wind power generator because of its capture wind energy efficiency at rated wind speed. At present, foreign countries have successfully applied direct torque control ( DTC ) technique in VSCF doubly-fed wind power generator, Whereas DTC exist the problems of low frequency excitation current aberrance and output torque ripple. Therefore, this paper puts forward the space vectors subdivision method to improve the low-frequency characteristicbased on the traditional direct torque control of doubly-fed generator, And structure the doubly-fed generator direct torque control experimental platform about the digital signal processor ( DSP ), realize the grid-connected power generation.

MPPT Method of Wind Power Based on Improved Particle Swarm Optimization

In order to improve the efficiency of wind energy, it is necessary to maximum power point tracking(MPPT). Aiming at shortage of the traditional particle swarm optimization algorithm for parameter sensitivity, easily local convergence, particle swarm optimization (PSO) algorithm with variable neighborhood based on saving preponderant velocities is proposed. Firstly, a compact formula for updating particles is researched, which is considering cognitive discipline of individual on its environment; secondly, a mutation operator with a small probability on the velocities which improve particle quality and a random vector generated for the rest velocities are proposed in order to make full use of good information of particle velocities; finally, the method is applied to maximum power point tracking control of the wind power generation system. The simulation results show that the proposed algorithm can achieve maximum power capture of wind power generation system, improve the dynamic response and efficiency compared with the traditional PSO algorithm. DOI: http://dx.doi.org/10.11591/telkomnika.v11i6.2670

The Effect of Transportation Energy Consumption on the Wind Energy Efficiency and CO2 Emission in Taiwan

Wind power has had a striking development in recent years. However, advanced materials and technology for manufacturing wind turbines are necessary but usually unavailable in a developing country like Taiwan. In such a case, the consumption of transportation energy, especially an international one, cannot be ignored while the energy efficiency of wind power systems is surveyed. Based on our analysis, three demonstration wind systems in Taiwan, Mailiao, Jhongtun, and Chunfong, were analyzed to examine how the consumption of transportation energy affects the energy return on investment (EROI) and CO2 emission for wind energy. We have found the EROI loss increases while the transportation energy consumption is considered. Notably, the transportation of mega wind turbines leads to more CO2 emission. Moreover, wind turbines in small load capacities have less transportation energy ratio, while mega turbines consume disproportionately more transportation energy.

Efficiency analysis and controller design of a continuous variable planetary transmission for a CAES wind energy system

This study proposes a CAES wind energy storage system composed of a windmill, a continuous variable planetary (CVP) transmission, a flywheel, a clutch, a reciprocating compressor, and an air tank. The mode of transformation of wind energy into compressed air in the system is also illustrated, in addition to details on the process of the controller design. The system controller can adjust the gear ratio according to the wind speed (Vwind) and rotational speed of the flywheel (ωflywheel). With a proper controller design to control the gear ratio, the flywheel can rapidly reach a rotational speed that is suitable for compressing the air into a tank. In addition, the windmill can be operated at the most efficient point. Therefore, transformation efficiency of wind energy into compressed air could be improved. After completion of the controller design, the efficiency of the two air compression systems (one system is driven directly by the windmill and another is driven by the flywheel) are compared to determining the target for improving performance in the future.