Wind Turbine Units Research Articles

Exact approach for charging of PEVs with V2G capability to improve micro‐grid reliability

Nowadays, the major proportion of fossil fuels is consumed in the transportation systems. Plug-in electric vehicles (PEVs) can play a significant role in reducing the petrol consumption. A large amount of additional electrical power demand needed for the charging of PEVs may adversely affect the electric grid reliability. Using the charging station in the micro-grids (MGs) to minimise the total system operation cost in the presence of PEVs with vehicle to grid (V2G) capability is becoming vitally important. In this work, a practical model for charging strategy of PEVs based on typical charge and discharge profiles given by the battery producers is considered. The problem is constrained by the loss of load probability index of reliability. The proposed strategy makes it possible to handle the generation shortage due to the outage of conventional units and intermittency of wind turbine units. Mixed Integer Non-linear programming is used for the optimal planning of MG in the presence of PEVs. Results show that an appropriate charge and discharge strategy may lead to a significant improvement in the reliability of the considered MG as well as a reduction in the operational cost of the total system.

Optimal scheduling of active distribution networks with penetration of PHEV considering congestion and air pollution using DR program

Congestion is one of the greatest issues in the power market planning which can create different problems for both consumers and producers. With the growth of the tendency to use distributed energy recourses (DER) and energy storages (ES), distribution networks have altered from passive to active. In this paper, the impact of Plug-in Electric Vehicles (PEV) on managing the congestion and air pollution reduction has been assessed with considering demand response program under the uncertainties of renewables. Various DERs and ESs including wind turbine, solar panels, combined heat and power units, PEVs have applied in the proposed modeling with the aim of the congestion and carbon emission alleviation. The uncertainties of renewable resources output modeled by the scenario generation and reduction method, then one of them has been chosen as an estimated scenario to simulate this modeling. Grey wolf optimization algorithm has been proposed to solve this mixed integer non-linear programming model. The results show that our proposed approach has minimized the total operation cost of ADNs along with reduction of congestion and CO2 emission. Furthermore, it improves some technical specification of the system such as voltage profile and power losses. Finally, a case study referring to the modified IEEE 69-bus distribution test system is utilized to proof the efficiency and proficiency of the suggested congestion relief method.

Probabilistic assessment of static voltage stability in distribution systems considering wind generation using catastrophe theory

With increasing penetration of distributed generations, the importance of the voltage stability assessment of distribution networks has been increased. Considering this situation, a probabilistic model is proposed to evaluate the voltage stability of distribution network integrating wind turbine (WT) units. With this intention, a probabilistic voltage stability index (PVSI) of a radial distribution system with wind power generation is presented. This index investigates the probabilistic risk of voltage collapse for all the buses of system considering uncertainty of WTs. Therefore, the most sensitive bus to the voltage collapse can be identified. The problem model is based on the catastrophe theory that can find the bifurcation point of system. Three-point estimation method is employed to calculate the statistical moments of voltage and PVSI of nodes. Moreover, to estimate the cumulative distribution function of output random variables, the Cornish−Fisher series are used. The performance of the probabilistic index is tested on the IEEE 69-bus radial distribution system where different load models are considered. The results demonstrate that the PVSI can accurately predict the voltage instability condition of the system.

Experimental Study of the Wake Regions in Wind Farms

It is desired, through this work, to investigate in detail the scenario that takes place behind a single wind turbine unit by focusing on three parameters; average axial wind velocity component, velocity deficit, and total turbulence intensity. The testing was done at mainstream velocity, U∞, of 5.2 m/s, u and v velocity components were captured by x-probe dual-sensor hot wire anemometer. A massive amount of point data was obtained, which then processed by a matlab script to plot the desired contours through the successive transverse sections along the entire length of the test section. By monitoring the previously mentioned flow parameters, the regions of low velocity and high turbulence can be avoided, while the location of the subsequent wind turbine is selected. The estimation of the distance, at which the inlet flow field will restore its original characteristics after being mixed through the rotor blades, is very important as this is the distance that should separate two successive turbines in an inline configuration wind farm to guarantee the optimum performance and to extract the maximum power out of the subsequent array of turbines. It is found that the hub height axial velocity recovery at six rotor diameters downstream distance is only 82%. This fact means that the power extraction out of the downstream turbine in an inline configuration wind farm is only 55% of the upstream turbine if the same free stream velocity and blade design are adopted.

Multi-objective optimized operation of integrated energy system with hydrogen storage

In this paper, an integrated energy system (IES) consisting of wind turbine unit, photovoltaic cell unit, electrolytic hydrogen unit, fuel cell unit, and hydrogen storage unit is proposed, and the construction of multi objectives for day-ahead power dispatching of the IES considering both operation and environment cost is discussed. By adopting piecewise linearization method, the optimization variables are divided into 24 periods, and the day-ahead power dispatching optimization problem is transformed into a 24-h piecewise optimization problem. On the basis, a complete non-linear mixed integer dynamic scheduling optimization model is established. An improved non-dominated sorting genetic algorithm (NSGA-II) is applied to solving the model. In optimization process, an interactive strategy is adopted to solve the coordination between discretization of variables and restriction of switching times of electrolyzer. Optimization results show that, compared with the single objective of minimizing operating costs, the multi-objective optimization scheme can reduce carbon emissions by 3.5% with 2.8% increase of operating cost. Compared with the single objective of minimizing environmental, the multi-objective optimization scheme can reduce operating cost carbon by 5.12% with 2.6% increase of environmental cost.

Multi-Searcher Optimization for the Optimal Energy Dispatch of Combined Heat and Power-Thermal-Wind-Photovoltaic Systems

This paper proposes a novel multi-searcher optimization (MSO) algorithm for the optimal energy dispatch (OED) of combined heat and power-thermal-wind-photovoltaic systems. The available power of wind turbine (WT) units and photovoltaic (PV) units is approximated with the probability density functions of wind speed and solar irradiance, respectively. The chaos theory is used to implement a wide global search, which can effectively avoid a low-quality local optimum for OED. Besides, a double-layer searcher is designed to guarantee fast convergence to a high-quality optimal solution. Finally, three benchmark functions and an energy system with 27 units are used for testing the performance of the MSO compared with nine other frequently used heuristic algorithms. The simulation results demonstrate that the proposed technique not only can solve the highly nonlinear, non-smooth, and non-convex OED problem of an energy system, but can also achieve a superior performance for the convergence speed and the optimum quality.

An experimental work on the performance of solar still incorporating with wind turbine and thermal energy storage unit

An experimental work on the performance of solar still incorporating with wind turbine and thermal energy storage unit

Research on Primary Frequency Regulation Control Strategy of Wind-thermal Power Coordination

With the increase of wind power penetration in the electric grid, the frequency regulation method that simply reply on traditional power is gradually weakened. For this reason, the participation of wind power in system frequency regulation has become an inevitable trend in the operation of large-scale grid-connected power system. Focused on the essential difference of the frequency response speed between wind turbine and thermal power unit, a primary frequency regulation control strategy for large-scale wind power cooperative thermal power units is proposed to realize frequency regulation in the full wind speed range of doubly-fed wind turbines and improve the frequency response capability of large-scale wind power access to system. Firstly, the frequency regulation response strategy of wind turbine based on rotor kinetic energy control and power reserve control and the control strategy of rotor speed recovery are studied to improve the frequency regulation capability of wind power system. Secondly, the optimal distribution of frequency regulation power of the large-scale wind farms is realized according to the establishing of the power distribution strategy based on weight factor of each turbine in the wind farm in different operating scenarios Finally, the control framework of wind-thermal power coordination frequency regulation is constructed. The system power shortage is distributed to the wind farm and the thermal power unit in real time by the dispatch center according to the wind farms' and thermal power unit's operating states and the variation of system frequency, by which the wind-thermal power coordination frequency regulation of power system can be achieved. Simulation results of the 36-node test example demonstrate that the proposed strategy can effectively improve the frequency response capability and the frequency characteristics of the power system.

Short-Term Scheduling Strategy for Wind-Based Energy Hub: A Hybrid Stochastic/IGDT Approach

This paper evaluates the scheduling problem for energy hub system consisting of wind turbine, combined heat and power units, auxiliary boilers, and energy storage devices via hybrid stochastic/information gap decision theory (IGDT) approach. Considering that energy hub plays an undeniable role as the coupling among various energy infrastructures, still it is essential to be investigated in both modeling and scheduling aspects. On the other hand, penetration of wind power generation is significantly increased in energy infrastructures in recent years. In response, this paper aims to focus on the hybrid stochastic/IGDT optimization method for the optimal scheduling of wind integrated energy hub considering the uncertainties of wind power generation, energy prices and energy demands explicitly in a way that not only global optimal solution can be reached, but also volume of computations can be lighten. In addition, by the proposed hybrid model, the energy hub operator can pursue two different strategies to face with price uncertainty, i.e., risk-seeker strategy and risk-averse strategy. This method optimizes energy hub scheduling problem in uncertain environment by mixed-integer nonlinear programming. This formulation is proposed to minimize the expected operation cost of energy hub where different energy demands of energy hub would be efficiently met. The forecast errors of uncertainties related to wind power generation and energy demands are modeled as a scenario, while an IGDT optimization approach is proposed to model electricity price uncertainty.

STATCOM Controller Design and Experimental Investigation for Wind Generation System

Controlling of Wind Generation System (WGS) is a vital process to adjust the value of voltage fluctuation that linked to the grid under variations of wind speed. In this paper, a variable speed wind-turbine unit coupled with permanent-magnet synchronous generator is modeled. STATCOM-control methodologies are established on the basis of two controllers; PI controller and Self-Tuning Fuzzy Logic PI-Controller (STFPC). Laboratory model of the WGS using DC motor with an armature current control is designed to achieve a real time simulation of the system. The results are evidenced on the validation of the suggested controlling methodologies. The paper presents experimental comparisons of STFPC with PI-controller. Also, the superiority of utilizing STFPC over PI-controller has been proven.

Research on Modeling of Microgrid Based on Data Testing and Parameter Identification

The model parameter identification based on real operation data is a means to accurately determine the simulation parameters of the microgrid, but the real operation data cannot guarantee the exact agreement with the required data for parameter identification, which has become an important restriction factor in the accurate simulation and analysis of the dynamics of the microgrid. This paper provides a method of modeling of microgrid based on data testing and parameter identification. In this paper, the method of parameter trajectory sensitivity is first introduced. Then, the data testing scheme for parameter identification is presented, and the parameter identification flow chart is given. Thirdly, a microgrid demonstration system in China is taken as an example, the important parameters of the distributed photovoltaic, direct-drive wind turbine and energy storage unit in the system are obtained by data testing and parameter identification, and in the end, the accuracy of the model is verified through the comparison of the simulation data and the test data of the microgrid during grid-connection/island switching process. The obtained microgrid model provides a base model for the analysis of the overall characteristics, such as the transient stability, as well as power quality of the microgrid.

Optimal stochastic scheduling of cryogenic energy storage with wind power in the presence of a demand response program

Abstract This paper provides a stochastic method to conduct the optimal scheduling of the combination of wind power and new-type large-scale energy storage with considering the demand response program in the electricity market. The integration of ASU and CES make the opportunity to store energy in the form of liquid in the off-peak periods and recovering the electricity in the peak periods. The uncertainty of electricity price, load demand and wind speed considered as the stochastic model uncertain parameters. The optimal operation of wind turbine, CES, and conventional generation units, considering the stochastic models for price, demand, and wind speed, was formulated as a mixed-integer non-linear programming (MINLP) problem. The constraints of CES operation, liquid and gas product demands, and ASU production were considered in ASU-CES modeling. The startup cost, minimum on/off time constraints, ramp rate, and capacity limits were considered in the formulation of conventional power generation. The demand response (DR) program was adopted to increase the total expected profit and decrease the total operational cost. The results revealed that the application of CES to attest system containing ASU increases the total profit of power generation units and decreases the total cost of generating power to serve load demands.

Dynamic response analysis of a catamaran installation vessel during the positioning of a wind turbine assembly onto a spar foundation

Installation of floating wind turbines is a challenging task. The time and costs are closely related to the installation method chosen. This paper investigates the performance of an efficient installation concept – a catamaran wind turbine installation vessel. The vessel carries pre-assembled wind turbine units including towers and rotor nacelle assemblies. Each unit is placed onto a pre-installed offshore support structure (in this paper a spar floater) during installation. The challenge is to analyse the responses of the multibody system (catamaran-spar-wind turbine) under simultaneous wind and wave loads. Time-domain simulations were conducted for the coupled catamaran-spar system with mechanical coupling, passive mooring system for the spar, and dynamic positioning control for the catamaran. We focus on the steady-state stage prior to the mating process between one turbine unit and the spar, and discuss the effects of wind loads and wave conditions on motion responses of the catamaran and the spar, relative motions at the mating point, gripper forces and mooring forces. The relative motion at the mating point is less sensitive to the blade orientation, but influenced by the wave conditions. Under the investigated sea states, the present installation method shows decent performance.

Multi‐criteria optimal sizing of hybrid renewable energy systems including wind, photovoltaic, battery, and hydrogen storage with ɛ‐constraint method

Hybrid renewable energy systems (HRES) should be designed appropriately with an adequate combination of different renewable sources and various energy storage methods to overcome the problem of intermittency of renewable energy resources. A multi-criteria approach is proposed in this study to design an HRES including wind turbine, photovoltaic panels, fuel cell, electrolyser, hydrogen tank, and battery storage unit with an intermittent load. Three design criteria including loss of power supply probability, total energy loss (TEL), and the power difference between generation and storing capacity (as TELSUB) are taken into account in minimising the total cost of the system considering the interest rate and lifetime. The justifications and advantages of using these criteria are thoroughly discussed along with appropriate presentation of the results. The purpose of considering TEL and TELSUB is discussed thoroughly. The e-constraint method is used to handle practical constraints of the proposed multi-criteria problem to construct a multi-objective fitness function. Shuffled frog leaping algorithm is implemented to achieve better optimal results. The proposed approach is implemented using real wind speed and solar irradiance data for a specific location with an intermittent load demand. The results verify performance of the proposed multi-criteria design procedure.

Optimal Sizing of Distributed Generations in DC Microgrids With Comprehensive Consideration of System Operation Modes and Operation Targets

With the continuous increasing requirement of dc power generations and dc electrical equipment, dc microgrids (MGs) show great natural advantages and development potential. In this paper, aiming at optimal sizing method of distributed generations (DGs) in the dc MGs, the output and capacity of photovoltaic units, wind turbine units, and an energy storage system (ESS) are presented based on the components structures and operation characteristics of the dc MGs. Due to the feature of the dc MGs that demands grid-connected converter (GCC) to exchange power with ac grid, the operating status of GCC and on-grid price are taken into account in the economic objective functions of the dc MGs. Meanwhile, with constraints including battery state of charge, loss of power supply probability (LPSP), renewable energy efficiency (REE), and so on, a particle swarm optimization algorithm is adopted to calculate the optimal sizing results targeting at the lowest annualized capital cost and operation & maintenance (O&M) cost. Furthermore, based on the analysis of the operation schemes of the dc MGs and the dynamic lifespan estimated results of ESS, an optimal sizing approach with comprehensive consideration of system operation modes and operation targets of the dc MGs is proposed. The variation trends of annualized capital cost and O&M cost are investigated under different LPSP and REE. Meanwhile, the system operation schemes are validated by using the obtained results, and the comparison and analysis of the detailed results are conducted.

The effect of hybrid savonius and darrieus turbine on the change of wake recovery and improvement of wind energy harvesting

The energy crisis encourages the development of renewable energy; one of the potential renewable energy is wind. In the field of wind turbine there is a two-way development of the utilization of wind energy, first by making a large wind turbine, the second by making a wind farm energy with a relatively small wind turbine. This hybrid VAWT wind turbine (Sultan Wind Turbine) is designed to work optimally on a farm array, on a wind turbine farm array will always cause a wake effect that will reduce overall wind turbine and farm array performance, an investigation with a CFD simulation is required to predict how far the wake effect will be before farm array build. The use of simulation software has been widely used to predict the effects of this wake, and experiments in the laboratory have also been done to predict the effects of a wake as well. This study's purpose is to predict the distance area of the recovery wake behind the wind turbine, this distance which will be the reference distance between wind turbine units and determining the density of the turbine in a farm. Simulation using Computational Fluid Dynamics (CFD), with a method of Multi Frame Reference (MRF). Analysis using descriptive and inferential method in statistics such as mean, Kolmogorov-Smirnov Z and Kruskal Walis test. From the analysis of simulation results and data processing descriptively and analytic statistic, it can be concluded from the data given, the distance of x/D=4, wind speed has recovery to the value near the input speed and no significant change to x/D= 9. Then it can be concluded that the distance between two wind turbines that can be used is a distance of 3.6 meters. These data suggest that the hybrid farm array VAWT savonius and darrieus have a higher power density compared to HAWT. From this power density calculation the hybrid VAWT has a greater electrical potential up to 300 percent compared to the HAWT farm array.

Design and evaluation of performance tester for yaw brakes in wind turbines

In this study, a new type of test equipment is proposed to verify the performance of yaw brakes. A Nacelle, one of the wind turbine unit, rotates every 15 minutes to adjust its position to perpendicular to the blowing wind, which is known for yawing motion. The nacelle contains a main shaft, a gear box, and a generator, so that the size and weight are huge. A yaw brake system is the main device to stop the rotating nacelle during the yawing motion. A big disc of which the diameter is about 2 meters and several brakes are installed at the bottom part of the nacelle. Due to the difficulty of the size, the performance test for the yaw brake is very difficult. New tester is designed using a partial disk to simulate the disk brakes in the nacelle, as well as the application of braking force by a hydraulic actuator located at double the radius of the disk in order to reduce the hydraulic power. The stresses and strains are calculated through CAE analysis, and the values are compared with those from strain gage tests. After verifying the performance of the tester and testing two kinds of brake pads, it is found that alumina and chromite increase the friction coefficients but produce vibration and sound noise.

Optimising operation management for multi‐micro‐grids control

Nowadays, renewable energy sources in a micro-grid (MG) system have increased challenges in terms of the irregularly and fluctuation of the photovoltaic and wind turbine units. It is necessary to develop battery energy storage. The MG central controller is helping to develop it in the MG system for improving the time of availability. Thus, reducing the total energy expenses of MG and improving the renewable energy sources (battery energy storage) are considered together with the operation management of the MG system. This study proposes fitness-based modified game particle swarm optimisation (FMGPSO) algorithm to optimise the total costs of operation and pollutant emissions in the MG and multi-MG system. The optimal size of battery energy storage is also considered. A non-dominated sorting genetic algorithm-III, a multi-objective covariance matrix adaptation evolution strategy, and a speed-constrained multi-objective particle swarm optimisation are compared with the proposed FMGPSO to show the performance. The results of the simulation show that the FMGPSO outperforms both the comparison algorithms for the minimisation operation management problem of the MG and the multi-MG system.

An optimal versatile control approach for plug-in electric vehicles to integrate renewable energy sources and smart grids

This study proposes a practical solution to deal with challenges of integrating renewable energy sources and electric vehicles into the electric grid, considering generation source intermittency and energy usage inconsistency, via a new adaptive intelligent controller. The present research describes a smart grid consisting of power plants and distributed generation, fueled via photovoltaic panels and wind turbines, and augmented with electric vehicles as power storage devices. Employing a parking lot to deal with challenges such as low penetration of the electric vehicles embedded with Vehicle-to-Grid functionalities encounters two difficulties: where they should be installed, and modeling of bi-directional power flow between electric vehicles, the grid, and the distributed generation system. In this regard, a nonlinear multi-objective problem is designed and solved via employing the Non-dominated Sorting Genetic Algorithm-II, and the forward and backward substitution method. In addition, Newton-Raphson Power Flow is adopted and modified to calculate the power flow of the distribution network. The results related to optimal placement and sizing of hybrid renewable energy systems show that bus 16 of the studied grid is the best place to integrate a parking lot – equipped with 117 photovoltaic and 10 wind turbine units - to the tested IEEE-26 buses. Furthermore, this study suggests that the aforementioned grid could employ a complex versatile control unit able to optimize the operating point, scheduling charging and discharging for a large number of electric vehicles while considering the technical aspects (total active power loss and voltage deviation). In this regard, a new hybrid control approach based on Particle Swarm Optimization-Adaptive Neuro-Fuzzy Inference System tuned via utilizing the optimal power flow problem is proposed. The controller's superiority to handle grid-to-vehicle and vehicle-to-grid services is discussed and compared to other studies.

并网风机群阻抗建模及系统谐振分析

风电并网系统的谐波谐振是导致全局并网系统谐振发生的重要原因，是电力系统稳定运行的潜在威胁。基于风电机组并网谐振技术原理，从阻抗角度对并网逆变器进行建模，提出并网风机群系统谐振分析方法。以实际风电场模型及参数为实例，通过MATLAB编程仿真，实现风机群系统谐振情况计算，分析风机并网台数、风机输出功率对谐振特性的影响。仿真计算验证了理论分析的正确性与谐振分析模型的有效性，对实际运行时风机群组的谐振问题分析和并网逆变器设计具有指导意义。 The harmonic resonance of wind power grid is an important reason leading to the resonance of global grid-connected system. It is a potential threat to the stable operation of the power system. Based on the grid-connected resonance principle of wind turbine generator, the grid-connected inverter impedance model is proposed to analyze the resonance of grid-connected wind turbine group. An actual wind farm model and parameters are modeled in MATLAB to calculate the reso-nance of grid-connected wind turbine group. The impact of wind turbine units number and output power to the resonant characteristics can be analyzed. The correctness of theoretical analysis and effectiveness of the resonance analysis model is supported by the experimental results. It has a certain guiding significance to resonance analysis of running wind turbines group and grid- connected inverter design.