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This paper presents application guidelines for a new generic plant controller model that can be used for renewable plant dynamic system analysis that may include the control of static compensators (STATCOMs), static var compensators (SVCs), and/or energy storage devices. The authors originally presented the need for such a model to the Western Electricity Coordinating Council (WECC) and contributed to various stages of the new model development led by WECC. As Independent System Operators (ISOs)/Regional Reliability Organizations (RTOs)/Transmission Service Providers (TSPs) are moving toward acceptance and use of generic models only the authors have for the first time applied this new model for an operating renewable plant. The new model was configured, parameterized, and tuned to control two STATCOMs and multiple switched capacitors/reactors to represent a master/auxiliary control strategy as implemented in the plant. Dynamic simulations show that the configured and parameterized model is performing properly as expected. This tuned model was submitted to the system operator for compliance with the interconnection requirements of the plant. This is the first submission of the new generic model for this type of control for a renewable project. The submitted model is appropriate for dynamic simulations, which are routinely performed by ISOs/RTOs/TSPs in system impact studies or transmission planning studies. This paper provides useful guidelines in applying this new model for similar projects. [ABSTRACT FROM AUTHOR]

This paper presents a distributed wind power virtual simulation experiment system for cultivating students' ability to solve complex engineering problems. The experiment system was designed with complex engineering problems of real wind farms, both in a steady state and transient process. On the basis of the system, comprehensive practical contents were developed. According to engineering education certification, the virtual simulation practical contents provide support for improving students' ability to solve complex engineering problems. The system has been applied to a comprehensive practical course of renewable energy. From the designed assessment, the experiment system helped students to master the advanced technologies applied to real wind farms visually and enhanced their ability to solve complex engineering problems. After practical learning on the system, students' performance has been improved in graduation projects. It is proved that the virtual simulation experiment system is effective in cultivating students' ability to solve complex engineering problems. [ABSTRACT FROM AUTHOR]

This paper introduces a new proposed design and optimization simulation program for the techno-economic sizing of a stand-alone hybrid photovoltaic/wind/diesel/ battery energy system using the iterative optimization. The main function of the new proposed simulation program is to determine the optimum size of each component of a hybrid renewable energy system for the lowest price of generated energy and the lowest value of dummy energy at highest reliability. An accurate methodology for pairing between five Saudi Arabia sites and ten wind turbines from different manufacturers to maximize energy production and minimize the price of the generated power is introduced. This methodology changes the penetration ratio of the renewable energy sources in certain increments to meet the load requirements of the sites under study. A detailed economic methodology to obtain the price of the generated energy is introduced. The new proposed simulation program is implemented in flexible fashion, which is not possible for the market-available software, such as HOMER, INSEL, TRNSYS, and RETScreen. The results obtained from the new proposed simulation program are compared with those from genetic algorithm and HOMER software to evaluate the effectiveness of the proposed program. Many valuable results can be extracted from the proposed program to assist researchers and decision makers. [ABSTRACT FROM AUTHOR]

A reliable approach based on a multi-verse optimization algorithm (MVO) for designing load frequency control incorporated in multi-interconnected power system comprising wind power and photovoltaic (PV) plants is presented in this paper. It has been applied for optimizing the control parameters of the load frequency controller (LFC) of the multi-source power system (MSPS). The MSPS includes thermal, gas, and hydro power plants for energy generation. Moreover, the MSPS is integrated with renewable energy sources (RES). The MVO algorithm is applied to acquire the ideal parameters of the controller for controlling a single area and a multi-area MSPS integrated with RES. HVDC link is utilized in shunt with AC multi-areas interconnection tie line. The proposed scheme has achieved robust performance against the disturbance in loading conditions, variation of system parameters, and size of step load perturbation (SLP). Meanwhile, the simulation outcomes showed a good dynamic performance of the proposed controller. [ABSTRACT FROM AUTHOR]

When a hexagonal converter (Hexverter) is applied to high-power renewable energy generation such as offshore low-frequency transmission, using traditional PID control to ensure the stable global operation and strong robustness of the system is difficult due to the random fluctuation of renewable energy, system parameter uptake, its non-linear characteristics, and the possible unbalanced grid situation. This paper proposes a non-linear passivity-based control (PBC) strategy for Hexverter under an unbalanced grid. First, the passivity and stability of Hexverter objects are analyzed based on PBC theory. The unbalanced PBC strategy of Hexverter is then designed and derived. Three control objectives are designed according to different control requirements. Finally, the simulation system of the Hexverter under an unbalanced grid is built on Matlab/Simulink to verify the effectiveness and superiority of the proposed unbalanced PBC method. The simulation results show that the proposed method has fewer control parameters, faster response, lower harmonic content, and better overall control effect than PID control. [ABSTRACT FROM AUTHOR]

This paper proposes an ac-linked hybrid windl photovoltaic (PV)/fuel cell (FC) alternative energy system for stand-alone applications. Wind and PV are the primary power sources of the system, and an FC-electrolyzer combination is used as a backup and a long-term storage system. An overall power management strategy is designed for the proposed system to manage power flows among the different energy sources and the storage unit in the system. A simulation model for the hybrid energy system has been developed using MATLAB/Simulink. The system performance under different scenarios has been verified by carrying out simulation studies using a practical load demand profile and real weather data. [ABSTRACT FROM AUTHOR]

This paper addresses power management strategies, including technical issues and control methodologies, for a wind-dominated hybrid remote area power supply (RAPS) system. The system consists of a doubly fed induction generator, a diesel generator, a hydrogen-based generation scheme, and mains loads. The goal is to maximize power extraction from the wind generator under generation uncertainty. For active power management, a hydrogen-based generation scheme consisting of an electrolyser and a fuel cell system is integrated to the RAPS system. Developed control strategies contribute to achieve the following objectives: 1) load side voltage and frequency regulation; 2) maximum power extraction from wind; and 3) regulating diesel generator operation at low load conditions. Simulation studies with a real-life data set are used to evaluate the proposed architecture and prove the control objectives, and it has been observed that all the proposed objectives are met within satisfactory limits. [ABSTRACT FROM PUBLISHER]

SUMMARY This paper investigates Japan's long-term energy outlook to 2050 taking into consideration the massive deployment of solar photovoltaic (PV) systems and wind power generation under a nuclear energy scenario. The extensive introduction of PV systems and wind power systems is expected to play an important role in enhancing electricity supply security after the Fukushima nuclear power accident, which has increased the uncertainty of the future additional construction of nuclear power plants in Japan. Against this background, we develop an integrated energy assessment model composed of both an econometric energy demand and supply model and an optimal power generation mix model. The latter model is able to explicitly analyze the impact of output fluctuations for various renewable energy sources at a detailed time resolution of 10 min on 365 consecutive days, incorporating the role of stationary battery technology. The simulation results reveal that intermittent fluctuations derived from a high penetration level of those renewables are controlled by quick load following operation by natural gas combined cycle power plants, pumped-storage hydro power, stationary battery technology, and output suppression of PV and wind power generation. The results show as well that massive penetration of renewables does not necessarily require a comparable scale of stationary battery capacity. Additionally, in the scenario, which assumes the decommissioning of nuclear power plants with a lifetime of over 40 years, the required PV capacity in 2050 amounts to more than double the PV installation potential in both buildings and abandoned farmland areas. [ABSTRACT FROM AUTHOR]

Systems consisting of multiple wind-generators along with a single battery bank are a sustainable alternative for supplying the energy requirements of remote locations not connected to the national grid. In this paper, a methodology for sizing and optimizing wind-battery systems employing multiple wind turbines is proposed. Uncertainty in wind resource availability is taken into account by formulating the problem as a chance constraint. Based on a time step simulation, subject to different technical and physical design constraints, the entire solution space in terms of the system design variables viz., generator rating, rotor diameter and battery bank size for a specified number of wind turbines and reliability requirement is generated. The domain containing all feasible solutions is the design space and it is a function of system reliability requirement and the number of wind turbines. From the design space of multiple wind turbine-battery systems, it is shown that with an increase in the number of wind generators, the rotor diameter, generator rating of individual turbines as well as battery bank size can be minimized along with a benefit in the overall cost of energy (US$/kWh). Additionally, by increasing the number of wind generators it is possible to comply with a stringent power supply reliability target which would otherwise not be possible. The strength of the proposed methodology lies in the visualization of alternative solutions and identification of the minimum and the maximum limits of various system design variables. [ABSTRACT FROM AUTHOR]

This paper deals with the flux detection of squirrel cage induction generator (SCIG) in wind power. A novel observer named impulsive observer is presented to estimate the states of SCIG. Conditions for the existence of the impulsive observer are established by using linear matrix inequalities. A realization for the observer in SCIG is proposed. Simulation results are provided to show the validation of the proposed method. [ABSTRACT FROM AUTHOR]

When wind farms are connected to weak distribution networks, significant flicker emission can be expected, and it might not comply with the enforced grid code limits. This paper investigates and analyzes the impact of the possible wind generator reactive power control modes on the produced flicker levels. A frequency-selective reactive power control scheme is also proposed that makes it possible to mitigate the wind generator flicker emission under any reactive power exchange mode of the machine with the grid while respecting the grid code power factor restrictions. A realistic short-term wind profile is used and simulations are conducted on a 2 MW DFIG unit. Flicker measurement is carried out per IEC Standard 61000-4-15. [ABSTRACT FROM PUBLISHER]

This paper proposes Latin hypercube sampling (LHS) methods for reliability analysis of power systems including renewable energy sources, with an emphasis on the fluctuation of bus loads and intermittent behavior of renewable generations such as wind and solar power. The LHS methods that are applicable for systems with correlated random variables—system load and renewable generation—are proposed. Reliability indices such as loss of load expectation and loss of load probability are estimated. Results from Monte Carlo (MC) sequential sampling, MC nonsequential sampling, and that from the proposed LHS methods are compared. It is shown that the proposed methods are as accurate as the other sampling methods while requiring much less CPU time. Two case studies modified from the Electric Reliability Council of Texas (ERCOT) and IEEE Reliability Test System (IEEE RTS) are presented to demonstrate the performances of the proposed sampling methods. [ABSTRACT FROM PUBLISHER]

The paper proposes synchronisation and power sharing schemes for fast connection and smooth operation of high penetration wind-diesel hybrid systems. The synchronisation is realised by controlling the power electronic interface of the wind energy systems rather than the classical diesel engine synchronisation scheme. The power sharing between the diesel and wind systems is achieved by a modified power-frequency droop control method. The proposed schemes are tested on a simulated hybrid system to demonstrate their effectiveness. [ABSTRACT FROM AUTHOR]

Due to their weak nature, such as low inertia, offshore energy hubs are prone to unprecedented fast dynamic phenomena. This can lead to undesired instability problems. Recent literature, with main focus on onshore systems, suggests that electrolysers could be an attractive option to support wind generators in the mitigation of balancing problems. This paper presents an Electromagnetic Transient (EMT) model for real-time simulation based study of the dynamics of active power and voltage responses of offshore hubs due to wind speed fluctuations. The purpose of this study was to ascertain the ability of an electrolyser to support an offshore energy hub under different scenarios and with different locations of the electrolyser. Two locations of Proton Exchange Membrane (PEM) electrolysers were considered: centralised (at the AC common bus of the hub) or distributed (at the DC link of the wind turbines). Numerical simulations conducted in RSCAD® on a 2 GW offshore hub with 4 × 500 MW wind power plants and 330 or 600 MW PEM electrolysers show that electrolysers can effectively support the mitigation of sudden wind speed variations, irrespective of the location. The distributed location of electrolysers can be beneficial to prevent large spillage of wind power generation during the isolation of faults within the hub. [ABSTRACT FROM AUTHOR]

This paper presents a new three-phase 12/8-pole doubly salient permanent-magnet (DSPM) machine for application to wind power generation. The key is to design and analyze the proposed DSPM generator, namely, the design of a new machine structure to achieve high power density and high robustness and the device of system operation to attain high efficiency. By using finite element analysis, the static characteristics of the proposed generator are given. Hence, the evaluation of system performances is conducted by computer simulation. Experimentation is also given to verify the validity of the proposed DSPM generator. [ABSTRACT FROM AUTHOR]

In order to relieve the influence of wind power uncertainty on power system operation, demand response and robust stochastic theory are introduced to build a stochastic scheduling optimization model. Firstly, this paper presents a simulation method for wind power considering external environment based on Brownian motion theory. Secondly, price-based demand response and incentive-based demand response are introduced to build demand response model. Thirdly, the paper constructs the demand response revenue functions for electric vehicle customers, business customers, industry customers and residential customers. Furthermore, robust stochastic optimization theory is introduced to build a wind power consumption stochastic optimization model. Finally, simulation analysis is taken in the IEEE 36 nodes 10 units system connected with 650 MW wind farms. The results show the robust stochastic optimization theory is better to overcome wind power uncertainty. Demand response can improve system wind power consumption capability. Besides, price-based demand response could transform customers’ load demand distribution, but its load curtailment capacity is not as obvious as incentive-based demand response. Since price-based demand response cannot transfer customer’s load demand as the same as incentive-based demand response, the comprehensive optimization effect will reach best when incentive-based demand response and price-based demand response are both introduced. [ABSTRACT FROM AUTHOR]

A small-scale wind energy conversion system can track the maximum power point (MPP) based on a linear relationship between Vdc^2 and Idc. Unlike conventional MPP tracking (MPPT) methods using a lookup table, an advanced technique is proposed based on this relationship as a variant of the perturb and observe (P&O) method. It not only has the advantages of the conventional P&O method but also has a faster tracking speed and better performance. This paper theoretically analyzes the possible power coefficient drop when using a linear relationship for MPPT and establishes that the turbine design can ensure that the possible power coefficient drop is small. The simulation results show that the analysis is precise. The validity and performance of the proposed MPPT method are confirmed by both simulation and experimentation. [ABSTRACT FROM PUBLISHER]

Copyright of Telkomnika is the property of Department of Electrical Engineering, Ahmad Dahlan University 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.)

There is a wide range of possible data representations, models and solution techniques available when conducting adequacy assessments of wind integrated generation or composite generation and transmission systems. This paper presents some of the basic factors and procedures that need to be considered when conducting wind integrated system adequacy assessment. Focus is placed on possible wind speed data models, wind energy conversion system models and their application in generation and bulk system adequacy evaluation. [ABSTRACT FROM PUBLISHER]

Improving the safety and stability of power systems by adjusting the controllable load to improve the wind power integration has become a hot research topic. However, the methodology of accurately controlling the load and fundamentally improving the wind power integration capacity has yet to be studied. Therefore, this paper proposes an intelligent regulation method for a controllable load. This method takes the new energy consumption assessment as feedback, and it combines the wind power acceptance assessment and scheduling plan to form the internal and external loop control structure, and it derives the controllable load intelligent regulation architecture. The load curve is decomposed by an interactive load observer, and the load curve is adjusted by the interactive load controller according to a given standard, thereby improving the new energy acceptance capability. Finally, based on the actual grid operation data of a provincial power grid in Northeastern China, the source grid load balancing process and the interactive load regulation model of the wind power system are simulated. The above method verifies the validity and rationality of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper different drive train models for wind generators has been studied in detail. Simscape-the physical system modeling software in MATLAB/SIMULINK has been used to verify the behavior of these models in a wind power system. Physical system simulation using simscape is comparatively easier than any other software that uses dynamic equations for the purpose. The torque, speed and power output of a fixed speed grid connected wind generator using various drive train models under changing wind conditions has been compared and analyzed. [ABSTRACT FROM AUTHOR]

Abstract: In this paper the design and simulation of two renewable-based standalone energy systems for application in two different locations are carried out. More specifically, the systems examined are a standalone PV system and a standalone hybrid PV–Wind system. The locations considered are those of Nicosia, Cyprus and Nice, France. These two locations have similar Mediterranean climates with different wind potential and slightly different solar irradiation levels which lead to interesting conclusions concerning the application of such systems. Since both systems are standalone, the energy produced is stored in a battery bank. The software used for the modeling and simulation processes is TRNSYS. The results of this paper define the optimal type and size of the renewable-based system to be applied in each of the locations examined at the minimum system cost. Additionally, a comparison of the two systems for both locations in terms of technical and economic aspects is presented where it is concluded that the type of the system to be used in each case is directly depended on the climatic characteristics of the specific location. More specifically, for Nicosia the solely PV system provides a better option than the PV–Wind hybrid system while in Nice the opposite is the case. [Copyright &y& Elsevier]

Abstract: This paper investigates the technical and economic potential of energy-intensive industries to provide demand-side management (DSM) in electricity and balancing markets through 2030. Increasing shares of renewables will lead to a rising demand for ancillary services at the same time that less conventional plants will be available to provide these services. This paper makes projections on the extent to which DSM from industrial processes can provide economic benefits in electricity markets with renewables by providing tertiary reserve capacity. Different industrial processes and their specific technical and economic properties are investigated and compared with other storage devices and electricity generation technologies. Based on an extension of an existing European electricity market model, simulations are used here to make long-term forecasts for market prices, dispatch and investments in the electricity markets through linear optimization. [ABSTRACT FROM AUTHOR]

This paper contributes a Markov chain Monte Carlo (MCMC) method for the direct generation of synthetic time series of wind power output. It is shown that obtaining a stochastic model directly in the wind power domain leads to reduced number of states and to lower order of the Markov chain at equal power data resolution. The estimation quality of the stochastic model is positively influenced since in the power domain, a lower number of independent parameters is estimated from a given amount of recorded data. The simulation results prove that this method offers excellent fit for both the probability density function and the autocorrelation function of the generated wind power time series. The method is a first step toward simple stochastic black-box models for wind generation. [ABSTRACT FROM AUTHOR]

The deployment of Renewable Energy Sources (RES) is driving modern power systems towards a fundamental green transition. In this regard, there is a need to develop models to accurately capture the variability of wind and solar photovoltaic (PV) power, at different geographical and temporal scales. This paper presents a general methodology based on meteorological reanalysis techniques allowing to simulate aggregated RES time series over large geographical areas. It also introduces a novel PV conversion approach based on aggregated power curves in order to capture the uncertainty associated to the technical characteristics of individual installations spread across large regions. The proposed methodology is validated using actual power data in Europe and can be applied to represent intermittent generation in network development plans, reliability and market studies, as well as operational guidelines. [ABSTRACT FROM AUTHOR]

The penetration level of renewable generation has increased significantly in recent years, which has led to operational concerns associated with the system ramping capability. Here, we propose the flexible ramping capacity (FRC) model, which considers the practical ramping capability of generation resources as well as the uncertainty in net load. The FRC model also incorporates the demand curve of the ramping capacity, which represents the hourly economic value of the ramping capacity. The model is formulated mathematically using ramp constraints, which are incorporated into unit commitment (UC) and economic dispatch (ED) processes. Simulations are carried out using a 10-unit system to compare the FRC model with conventional methods. We show that the FRC method can improve reliability and reduce expected operating costs. The simulation results also show that, by using the FRC model, system reliability can be satisfied at high wind power generation levels while achieving economic efficiency. [ABSTRACT FROM AUTHOR]

This paper presents a scenario-based simulation analysis of the operation of the insular power system of Crete, Greece, on an hour-by-hour basis aiming at the evaluation of the impact of high Renewable Energy Sources (RES) penetration on the short-term power system scheduling. The possibility of introducing a pumped-storage plant as a storage facility to alleviate the negative effects of increased RES generation on the short-term operation is also investigated. The renewable generation impact is evaluated in terms of specific system indicators. An integrated software tool that performs annual simulation of the insular power system with hourly granularity aiming at the minimization of the total production cost while respecting the system and various generating unit operating constraints is used. Simulation results for the year 2015 provide quantitative assessment of the insular power system performance regarding its short-term operation under large-scale RES penetration and valuable conclusions are drawn. [ABSTRACT FROM AUTHOR]

Renewable energies are a central element in the search for energy sustainability, so they are becoming a substantial component of the energy scenario of every country, both as systems connected to the grid or in stand-alone applications. Feasibility of these renewable energy systems could be necessary not only in their application in isolated areas, but also in systems connected to the grid, in this last case when their contribution reaches a substantial fraction of the total electricity demand. To overcome this reliability problem, hybrid renewable systems could become essential and activities to optimize their design should be addressed, both in the simulation and in the experimental areas. In this paper, a laboratory to simulate and verify the reliability of hybrid renewable systems is presented and its application to the feasibility analysis of multicomponent systems including photovoltaic panels, wind generator and biomass gasification plant, plus energy storage in a battery bank, are described. [ABSTRACT FROM AUTHOR]

The increasing installation of volatile renewable energy sources like photovoltaics and wind enforces the need for flexibility options to match the renewable generation with the demand. One of these options is Demand Side Management (DSM) in the context of building energy systems combined with thermal storage systems. This paper discusses such concepts for DSM. A method for analyzing the flexibility that is needed to maintain the stability of the electrical grid is presented followed by the restrictions that are caused by meeting the heat demand and satisfying the comfort criteria of the residents. Approaches for simultaneously fulfilling these constraints as well as matching the flexibility needs of the electrical grid and the flexibility provided by the local building energy systems are discussed. To enhance the analysis options for the shown systems, a simulation platform that covers the electrical grid simulation, the building systems’ simulation and the control strategies is presented. This platform can be used to analyze different scenarios of building energy systems with different penetrations of renewable energy sources and different building types. [ABSTRACT FROM AUTHOR]

Abstract: Nowadays, renewable energy systems are taking place than the conventional energy systems. Especially, PV systems and wind energy conversion systems (WECS) are taking a big role in supplying world's energy necessity. Efficiency of such types of renewable energy systems is being tried to be improved by using different methods. Besides conventional methods, intelligent system designs are seem to be more useful to improve efficiency of renewable energy systems. However, artificial neural networks (ANN) have many usage areas in modeling, simulation and control of renewable energy systems. ANNs are easy to use and to implement renewable energy system designs. In this paper, artificial neural network applications of PV, WECS and hybrid renewable energy systems which consist of PV and WECS are presented. Usage of neural network structures in such types of systems have been motivated. [Copyright &y& Elsevier]

Abstract: Increasing levels of intermittent renewables, especially wind power, in energy systems require accurate temporal characterisation of the resources’ availability at seasonal, daily and hourly scales. This is crucial for isolated energy systems, where increasing wind power penetration is limited due to costly backup power generation requirements. In the case studies presented in this paper, the energy systems of two islands are simulated using a new methodology for synthetic wind speed scenarios including daily wind patterns. A trade-off analysis was conducted in terms of surplus wind power and renewables penetration rate, with the objective of supplying decision support on wind turbine placement. Results show that there may be a significant advantage in locating future wind parks on sites where wind speed patterns better match electricity demand patters, rather than just choosing a site with the highest mean wind speed, but only if the annual mean wind speed is still sufficiently high to make the investment economically feasible. [Copyright &y& Elsevier]

Abstract: Traditional economic dispatch focuses mainly on minimizing the total operation cost of the power system. With the appearance of energy crisis and environmental pollution becoming a public issue, environmental effect of generator should be taken into consideration through the dispatch process. In this paper a multi-objective dispatch problem considering the integration of wind power is solved whose objectives include the generation cost, the reserve capacity and the environmental emission. To compromise different objectives, a coordination degree combined with a satisfaction degree are introduced in order to transform the multi-objective dispatch problem into a single-objective one, i.e., the optimal generation dispatch (OGD) model. Then the OGD is solved by a particle swarm optimization algorithm on an IEEE 30-bus system, with wind power generation and coal-fired generation embedded. The simulation results show that better results in terms of all the three objectives can be obtained from the OGD model, in comparison with two other multi-objective dispatch models. The simulation results also show that the integration of wind power will cause the increase of both the generation cost and the reserve capacity but will decrease the environmental emission. [Copyright &y& Elsevier]

Abstract: Two of the most significant challenges in the 21st century will be to improve energy security and reduce the greenhouse gas emissions associated with energy consumption. A co-beneficial solution to these challenges is seen as increasing the use of renewable energy for the production of electricity. Some renewable sources, such as wind are often presented as a way to reduce greenhouse gas emissions; however, since wind’s variability increases uncertainty and risk in expected generation, it can be detrimental to energy security. One of the ways in which wind’s contribution to a jurisdiction’s energy security and greenhouse gas reduction strategies can be improved is to employ a forecasting method that can help reduce risks. This paper proposes a method that applies risk and reliability analysis techniques to obtain the most-likely RL (Resistance–Load) scenario using a set of historical data for wind-supply or generation and load. RL estimates the reliability of a wind-energy system by simulating an anticipated resistance (the electrical generation) attempting to meet a load (the electricity demand) for a future year. The method is demonstrated through a case study and its results are compared with real-time data from a 12MW wind farm to prove its efficacy. [Copyright &y& Elsevier]

Abstract: Wind energy has been receiving more acceptance as a reproducible, resourceful and clean energy source since last decade. Wind power is not constant and may fluctuate below the rated wind power when the wind speed is lower than the rated speed. This fact affects the stability of the power system, to which the wind generators are connected. This is becoming more significant with the increasing penetration of wind energy systems. Pitch angle control has been one of the most common methods for smoothing output power fluctuations during below rated wind incidents. A fuzzy logic pitch angle controller is proposed in this paper for smoothing wind power fluctuations during below rated wind incidents beside traditional power regulations during above rated wind incidents. Two smoothing methods have been presented: the determination of the command output power based on the exponential moving average with a proper selection of correction factor by fuzzy reasoning and the dynamic selection of target output power according to the wind incident. Simulation results show the effectiveness of the proposed fuzzy logic pitch angle controller in smoothing output power fluctuations with significantly small drop of output power. [Copyright &y& Elsevier]

Abstract: Hydrogen has been recognized as the most promising future energy carrier. At present, industrial hydrogen production processes are not independent of traditional energy resources, which could easily cause secondary pollution. China has abundant wind energy resources. The total installed capacity of wind power doubled every year in the last five years, and reached 26 000 MW by the end of 2009, but over 9880 MW wind turbines were not integrated into grid because of the peak shaving restraint. In this paper, wind power is directly used in water-electrolytic process by some technical improvements, to design non-grid-connected wind power/water-electrolytic hydrogen production system. The system all works properly, based on not only the wind/grid complementary power supply but also the independent supply of simulation wind power. The large-scale fluctuation of current density has little impact on current efficiency and gas quality, and only affects gas output. The new system can break through the bottlenecks of wind power utilization, and explore a diversified development way of large-scale wind power, which will contribute to the development of green economy and low carbon economy in China. [Copyright &y& Elsevier]

Abstract: This paper presents an analysis and operation of doubly-fed induction generator (DFIG)-based wind power generation systems under unbalanced network voltage conditions. The limited voltage and current ratings, and control capabilities of both grid side and rotor-side converters (GSC&RSC) for unbalanced network voltage compensation are investigated. A current control scheme consisting of a proportional integral (PI) controller plus a resonant (R) compensator is designed. The control scheme is implemented in the positive synchronous rotating reference frame and provides precise current control for both the GSC and RSC without involving the decomposition process of positive and negative sequence currents. By taking into account both the converters’ current ratings, a coordinated control strategy between the GSC and RSC is proposed and adjusted. Finally, simulation studies on a 1.5 MW DFIG generation system and experimental tests on a 1.5 kW prototype are carried out. The correctness of the analytical results as well as the feasibility of the proposed coordinated control scheme are confirmed when the network voltage is unbalanced. [ABSTRACT FROM AUTHOR]

Abstract: Renewable distributed generation introduced as an environmental friendly alternative energy supply while it provided the power system with ever-growing technical benefits such as loss reduction and feeder voltage improvement. The evaluation of the effects of small residential photovoltaic and wind DG systems on various system operating indices and the system net load is complicated by both the probabilistic nature of their output and the variety of their spatial allocations. The increasing penetration of renewable distributed generation in power systems necessitates the modeling of this stochastic structure in operation and planning studies. An advanced stochastic modeling of the system requires multivariate uncertainty analysis involving non-normal correlated random variables. Such an analysis is to epitomize the aggregate uncertainty corresponding to spatially spread stochastic variables. In this paper, an integration study of photovoltaics and wind turbines, distributed in a distribution network, is investigated based on the stochastic modeling using Archimedean copulas as a new efficient tool. The basic theory concerning the use of copulas for dependence modeling is presented and focus is given on an Archimedean algorithm. A comprehensive case study for Davarzan area in Iran is presented after reviewing Iran''s renewable energy status. This study shows an application of the presented technique when large datasets, assuming 10-min interval between data points of PV, wind and load profiles, are involved where a deterministic study is not trivial. [Copyright &y& Elsevier]

Abstract: The paper presents the aerodynamic design of a ventilation device suitable for remote open areas, such as desert terrains. The device is attached to the top of an enclosure roof and employs wind energy to create a partial vacuum in a specially designed duct to draw out the stale air from within the enclosure. The design is developed with the aid of fluid flow simulation software that is employed to predict the flow details corresponding to different geometric shapes so that an efficient shape may be found. The software is also employed to predict the performance of the adopted shape for different operating conditions and the results are presented in the form of characteristics curves and a correlation equation. Reliability of predictions is backed by results of experimental validation presented elsewhere, and by performing a detailed grid-dependence study, as well as a domain extent sensitivity analysis. [Copyright &y& Elsevier]

Abstract: In recent years, electric power systems are adopting new technologies in their structure in order to achieve better performance and efficiency in the electricity production, transmission and distribution. This fact together with additional financial incentives being developed in many countries have increased considerably the number of power generating units using renewable energy sources. However, a major drawback of these units is their dependency on unexpected weather conditions such as the wind speed and the rainfalls in the respective hydrologic areas. The purpose of this paper is to investigate the impact of wind parks and hydroelectric power plants on the reliability and operational performance of isolated power systems. A probabilistic methodology has been developed for simulating more efficiently and realistically the reliability and operational performance of these power systems. This is an effective computational methodology that is based on the Monte-Carlo sequential simulation approach and it evaluates the reliability and operational indices of the conventional thermal and hydroelectric power plants, the wind parks and the overall indices of the system. An appropriate model based on the power system of a Greek island is used and the obtained results are presented for a number of case studies representing various planning and operating schemes in order to deduce the optimal one. [Copyright &y& Elsevier]

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We present a review of existing wind–wave coupling models and parameterizations used for large-eddy simulation of the marine atmospheric boundary layer. The models are classified into two main categories: (i) the wave-phase-averaged, sea surface–roughness models and (ii) the wave-phase-resolved models. Both categories are discussed from their implementation, validity, and computational efficiency viewpoints, with emphasis given on their applicability in offshore wind energy problems. In addition to the various models discussed, a review of laboratory-scale and field-measurement databases is presented thereafter. The majority of the presented data have been gathered over many decades of studying air–sea interaction phenomena, with the most recent ones compiled to reflect an offshore wind energy perspective. Both provide valuable data for model validation. We also discuss the modeling knowledge gaps and computational challenges ahead. [ABSTRACT FROM AUTHOR]

In this study long-term wind data obtained from high-resolution hindcast simulations is used to analytically assess offshore wind power potential in the Aegean and Ionian Seas and provide wind climate and wind power potential characteristics at selected locations, where offshore wind farms are at the concept/planning phase. After ensuring the good model performance through detailed validation against buoy measurements, offshore wind speed and wind direction at 10 m above sea level are statistically analyzed on the annual and seasonal time scale. The spatial distribution of the mean wind speed and wind direction are provided in the appropriate time scales, along with the mean annual and the inter-annual variability; these statistical quantities are useful in the offshore wind energy sector as regards the preliminary identification of favorable sites for exploitation of offshore wind energy. Moreover, the offshore wind power potential and its variability are also estimated at 80 m height above sea level. The obtained results reveal that there are specific areas in the central and the eastern Aegean Sea that combine intense annual winds with low variability; the annual offshore wind power potential in these areas reach values close to 900 W/m2, suggesting that a detailed assessment of offshore wind energy would be worth noticing and could lead in attractive investments. Furthermore, as a rough estimate of the availability factor, the equiprobable contours of the event [4 m/s ≤ wind speed ≤ 25 m/s] are also estimated and presented. The selected lower and upper bounds of wind speed correspond to typical cut-in and cut-out wind speed thresholds, respectively, for commercial offshore wind turbines. Finally, for seven offshore wind farms that are at the concept/planning phase the main wind climate and wind power density characteristics are also provided. [ABSTRACT FROM AUTHOR]

Wind energy is of increasing importance for a sustainable energy supply worldwide. At the same time, concerns about the number of birds and bats being killed at wind turbines have been growing. In this situation, methods for a reliable estimation of bird and bat fatality numbers are needed. To obtain an unbiased estimate of the number of fatalities from fatality searches, the probability to detect the carcass of an animal being killed at a turbine has to be assessed by considering carcass persistence rate, searcher efficiency and the probability that a killed animal falls into a searched area. Here, we describe a new formula to determine the detection probability of birds or bats that are killed at wind turbines and which can estimate the number of fatalities from the number of carcasses found. The formula was developed to analyse a large data set of bats killed at wind turbines in Germany. In simulations, we compared it to three other formulas used in this context. Our new formula seems to have unbiased results when searcher efficiency and carcass removal rate are constant over time. When searcher efficiency or carcass removal rate varied with time, all four formulas showed a similar bias. These comparative results can be used to choose between methods depending on the quality of information available. Our estimator can, for instance, be adapted to different situations including temporal changes of searcher efficiency or carcass removal rate because it is based on an explicit process model. [ABSTRACT FROM AUTHOR]

As the use of renewable energy sources (RESs) increases worldwide, there is a rising interest on their impacts on power system operation and control. An overview of the key issues and new challenges on frequency regulation concerning the integration of renewable energy units into the power systems is presented. Following a brief survey on the existing challenges and recent developments, the impact of power fluctuation produced by variable renewable sources (such as wind and solar units) on system frequency performance is also presented. An updated LFC model is introduced, and power system frequency response in the presence of RESs and associated issues is analysed. The need for the revising of frequency performance standards is emphasised. Finally, non-linear time-domain simulations on the standard 39-bus and 24-bus test systems show that the simulated results agree with those predicted analytically. [ABSTRACT FROM AUTHOR]

Presents a simulation method that provides objective indicators to help system planners decide on appropriate installation sites, operating policies and selection of energy types, sizes and mixes in capacity expansion when utilizing wind energy in small isolated power systems (SIPS). Reason behind the growth in the application of renewable energy in electric power systems; Adequacy evaluation of SIPS.

The main objective of the present study is to quantify the recent past and explore the near future wind power potential in the Black Sea basin, evaluating the possible changes. Furthermore, an analysis of the wind climate in the target area was also performed. The wind resources have been assessed using the wind fields provided by various databases. Thus, the wind power potential from the recent past was assessed based two different sources covering each one the 30-year period (1981–2010). The first source is the ERA-Interim atmospheric reanalysis provided by the European Centre for Medium-Range Weather Forecasts (ECMWF), while the second source represents the hindcast wind fields simulated by a Regional Climate Model (RCM) and provided by EURO-CORDEX databases. The estimation of the near future wind power potential was made based on wind fields simulated by the same RCM under future climate projections, considering two Representative Concentration Pathways (RCPs) scenarios (RCP4.5 and RCP8.5) and they cover also a 30-year time interval (2021–2050). Information in various reference points were analyzed in detail. Several conclusions resulted from the present work. Thus, as regards the mean wind power potential in winter season, in 51% of the locations a significant increase is projected in the near future (both scenarios). Besides providing a detailed description of the wind conditions from the recent past over the Black Sea basin considering two major sources, the novelty of the present work consists in the fact that it gives an estimation of the expected wind climate in the target area for the near future period and at the same time an evaluation of the climate change impacts on the wind speed and wind power potential. [ABSTRACT FROM AUTHOR]