Co-Simulation of an SRG Wind Turbine Control and GPRS/EGPRS Wireless Standards in Smart Grids

Wind energy can be considered a push-driver factor in the integration of renewable energy sources within the concept of smart grids.For its full deployment,it requires a modern telecommunication infrastructure for transmitting control signals around the distributed generation,in which,the wireless communication standards stand out for employing modern digital modulation and coding schemes for error correction,in order to guarantee the power plant operability.In some developing countries,such as Brazil,the high penetration of commercial mobile wireless standards GPRS and EGPRS(based on GSM technology)have captivated the interests of the energy sector,and they now seek to perform remote monitoring and control operations.In this context,this article presents a comparative performance analysis of a wireless control system for a wind SRG,when a GPRS or EGPRS data service is employed.The system performance is analyzed by co-simulations,including the wind generator dynamics and the wireless channel effects.The satisfactory results endorse the viability and robustness of the proposed system.

Physics-Informed AI Surrogates for Day-Ahead Wind Power Probabilistic Forecasting with Incomplete Data for Smart Grid in Smart Cities

Due to the high inherent uncertainty of renewable energy,probabilistic day-ahead wind power forecasting is crucial for modeling and controlling the uncertainty of renewable energy smart grids in smart cities.However,the accuracy and reliability of high-resolution day-ahead wind power forecasting are constrained by unreliable local weather prediction and incomplete power generation data.This article proposes a physics-informed artificial intelligence(AI)surrogates method to augment the incomplete dataset and quantify its uncertainty to improve wind power forecasting performance.The incomplete dataset,built with numerical weather prediction data,historical wind power generation,and weather factors data,is augmented based on generative adversarial networks.After augmentation,the enriched data is then fed into a multiple AI surrogates model constructed by two extreme learning machine networks to train the forecasting model for wind power.Therefore,the forecasting models’accuracy and generalization ability are improved by mining the implicit physics information from the incomplete dataset.An incomplete dataset gathered from a wind farm in North China,containing only 15 days of weather and wind power generation data withmissing points caused by occasional shutdowns,is utilized to verify the proposed method’s performance.Compared with other probabilistic forecastingmethods,the proposed method shows better accuracy and probabilistic performance on the same incomplete dataset,which highlights its potential for more flexible and sensitive maintenance of smart grids in smart cities.

Added Value of Power Control in Improving the Integration of Wind Turbines in Weak Grid Conditions

For economical reasons, wind turbine systems must be located in favourable sites generating a higher pro- ductivity. These are often located in areas with weak electric grid infrastructures. The constraints related to this type of grids limit the penetration levels of wind energy. These constraints are mainly related to power quality in the grid as well as the economical aspects of the project. In this study, we take into account the slow voltage variations and the flicker phenomenon. The models used are based on the development of a set of relations derived from engineering knowledge related to both technical and economical points of view. The maximal penetration level of a fixed speed wind turbine system is determined for a given grid. The power control has been investigated to improve wind turbine system integration. Obtained results show the necessity to adapt technological choices to the requirements of weaker grids. Penetration levels and wind turbine cost may be greatly improved using variable speed systems.

Increasing the Efficiency of Grid Tied Micro Wind Turbines in Low Wind Speed Regimes

Major problem with grid tied micro wind turbine is synchronization and wind variability. Due to this problem the stability of available grid gets reduced. The stability can be achieved by output power control of the turbine. Major part of many countries like India, the annual mean wind speed is not high. The rated wind speed of turbine remain around 11 m/s and cut in is around 3.5 m/s. Due to this problem we aimed to develop a sustainable wind energy system that can provide stable power supply even at the locations of low wind speed of 2 - 4 m/s. To address this issue, a momentary impulse or external torque to the rotor by external motor is one of the good options to maintain the momentum of blades and thus provide stability for sufficient time. Various theoretical calculations and experiments are conducted on the above method. This would increase the output power and also the efficiency of wind turbine. We show that Return-On-Investment will be high as compared with other grid connected turbines. Our proposed concept in the present study, if implemented properly, can help the installation of number of wind turbines even at domestic level. It also makes the consumers energy independent and promotes the use of wind as a source of energy and may enter as a rooftop energy supply system similar to solar.

Grid Harmonic and Control Delay Compensation for Three-phase Grid-connected VSIs in Small Wind Turbine Systems

Voltage space vector pulse-width modulation(SVPWM) has been widely applied to control current in three-phase voltage source inverters(VSI).However,as a voltage type modulator,SVPWM has certain drawbacks compared with current type modulators for grid-connected applications.For a grid-connected VSI,the performance of existing current controllers based on SVPWM is compromised by grid harmonics,control delay and system nonlinearities such as switching dead time.Moreover,unlike current type PWM,SVPWM does not inherently have over-current protection.A novel SVPWM-based current controller is proposed for three-phase grid-connected VSIs for small wind turbine appli-cations.To overcome the drawbacks of SVPWM,a grid harmonic compensation method is proposed along with compen-sation for control delays.Both simulation and experimental results have established excellent steady-state response and fast dynamic response of the current controller.In addition,the DSP-based control system has both improved real-time control performance and fast response for over-current protection.

The Third-Order Viscoelastic Acoustic Model Enables an Ice-Detection System for a Smart Deicing of Wind-Turbine Blade Shells

The present work is based on the third-order partial differential equation (PDE) of acoustics of viscoelastic solids for the quasi-equilibrium (QE) component of the average normal stress. This PDE includes the stress-relaxation time (SRT) for the material and is applicable at any value of the SRT. The notion of a smart deicing system (SDS) for blade shells (BSs) of a wind turbine is specified. The work considers the stress in a BS as the one caused by the operational load on the BS. The work develops key design issues of a prospective ice-detection system (IDS) able to supply an array of the heating elements of an SDS with the element-individual spatiotemporal data and procedures for identification of the material parameters of atmospheric-ice (AI) layer accreted on the outer surfaces of the BSs. Both the SDS and IDS flexibly allow for complex, curvilinear and space-time-varying shapes of BSs. The proposed IDS presumes monitoring of the QE components of the normal stresses in BSs. The IDS is supposed to include an array of pressure-sensing resistors, also known as force-sensing resistors (FSRs), and communication hardware, as well as the parameter-identification software package (PISP), which provides the identification on the basis of the aforementioned PDE and the data measured by the FSRs. The IDS does not have hardware components located outside the outer surfaces of, or implanted in, BSs. The FSR array and communication hardware are reliable, and both cost- and energy-efficient. The present work extends methods of structural-health/operational-load monitoring (SH/OL-M) with measurements of the operational-load-caused stress in closed solid shells and, if the prospective PISP is used, endows the methods with identification of material parameters of the shells. The identification algorithms that can underlie the PISP are computationally efficient and suitable for implementation in the real-time mode. The identification model and algorithms can deal with not only the single-layer systems such as the BS layer without the AI layer or two-layer systems but also multi-layer systems. The outcomes can be applied to not only BSs of wind turbines but also non-QE closed single- or multi-layer deformable solid shells of various engineering systems (e.g., the shells of driver or passenger compartments of ships, cars, busses, airplanes, and other vehicles). The proposed monitoring of the normal-stress QE component in the mentioned shells extends the methods of SH/OL-M. The topic for the nearest research is a better adjustment of the settings for the FSR-based measurement of the mentioned components and a calibration of the parameter-identification model and algorithms, as well as the resulting improvement of the PISP.

Connecting Wind Turbine Generator to Distribution Power Grid--A Preload Flow Calculation Stage

A distribution grid is generally characterized by a high R/X （resistance/reactance） ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in such a way that power flows from transmission system via distribution system to consumers. But in a situation when wind turbines are connected to the distribution grid, the power source will change from one source to two sources, in this case, network is said to be active. This may probably have an impact on the distribution grid to whenever the wind turbine is connected. The best way to know the impact of wind turbine on the distribution grid in question is by carrying out load flow analysis on that system with and without the connection of wind turbines. Two major fundamental calculations： the steady-state voltage variation at the PCC （point of common coupling） and the calculation of short-circuit power of the grid system at the POC （point of connection） are necessary before carrying out the load flow study on the distribution grid. This paper, therefore, considers these pre-load flow calculations that are necessary before carrying out load flow study on the test distribution grid. These calculations are carded out on a test distribution system.

High Performance Double-Interleaved Dual Boost Converter and 3 Phase Grid Connected Converter for Wind Turbine

This paper proposes a high performance double-interleaved dual boost （DIDB） technique to solve the problems of high ripple current, large inductor size and the requirement of step-up transformer in many case found in the conventional DC-DC boost converter. The 3-phase grid connected converter with decoupling control give an independent control between active and reactive power using the load current feed-forward. With this technique, the disturbance rejection and the output power quality can be improved. Experiments are conducted with three case studies： 1） a test of the DIDB converter to determine current ripple and voltage gain, 2） a test of the 3-phase grid connected converter to determine DC-link voltage regulation, power factor and total harmonic distortion （THD）, and 3） a test of the overall system with a 7.5 kW wind turbine simulator by step and various input wind speeds to determine the output power at the grid side and verify the maximum peak power tracking （MPPT） performance. The results can confirm that the DIDB converter gives lower ripple current and higher voltage gain than the conventional converter. For the grid side, the 3-phase grid connected converter can regulate the DC-link with fast dynamic response to disturbance rejection and low overshoot while complying with the THD standard defined in IEEE 519-1992. In addition, the MPPT controller is able to achieve the maximum energy capture with the various input wind speeds.

Optimizing Decision-Making of A Smart Prosumer Microgrid Using Simulation

Distributed renewable energy sources offer significant alternatives for Qatar and the Arab Gulf region’s future fuel supply and demand.Microgrids are essential for providing dependable power in difficult-to-reach areas while incorporating significant amounts of renewable energy sources.In energy-efficient data centers,distributed generation can be used to meet the facility’s overall power needs.This study primarily focuses on the best energy management practices for a smart microgrid in Qatar while taking demandside load management into account.This article looked into a university microgrid in Qatar that primarily aimed to get all of its energy from the grid.While diesel generators are categorized as a dispatchable distributed generation with energy storage added to handle solar radiation from the sun and high grid power operating costs in the suggested scenario,wind turbines and solar Photovoltaic(PV)are classified as non-dispatchable distributed generators.The resulting linear math issues are assessed and displayed in MATLAB optimization software using a mixed-integer linear programming(MILP)strategy.According to the simulation results,the suggested energy management strategy reduced the university microgrid’s grid power costs by 38.8%,making it an affordable solution which is somehow greater than the prior case scenario’s 23%savings.The installed solar system capacity’s effects on the economy,society,and finances were also assessed,and it became clear that the best option for the smart microgrid was determined that would be 325 kW of solar PV,25 kW of wind turbine,and 600 kW of diesel generators,respectively.Given the current situation,university administrators are urged to participate in distributed generators and adopt cutting-edge designs for energy storage technologies due to the significant environmental and financial benefits.

Impact of Reactive Power in Power Evacuation from Wind Turbines

Application of Distributed Generation (DG) to supply the demands of a diverse customer base plays a vital role in the renewable energy environment. Various DG technologies are being integrated into power systems to provide alterna-tives to energy sources and to improve reliability of the system. Power Evacuation from these remotely located DG’s remains a major concern for the power utilities these days. The main cause of concern regarding evacuation is con-sumption of reactive power for excitation by Induction Generators (IG) used in wind power production which affects the power system in variety of ways. This paper deals with the issues related to reactive power consumption by Induc-tion generators during power evacuation. Induction generator based wind turbine model using MATLAB/SIMULINK is simulated and its impact on the grid is observed. The simulated results are analyzed and validated with the real time results for the system considered. A wind farm is also modeled and simulations are carried out to study the various im-pacts it has on the grid &nearby wind turbines during Islanding and system event especially on 3-Phase to ground fault.

Optimization of Building Layouts to Increase Wind Turbine Power Output in the Built Environment Assumed to Be Installed at Fukushima City and Tsu City in Japan

It is very important to consider proper intelligent integration and locations of renewable energy sources into the built environment for developing smart cities. Wind speed distribution study in the built environment is very essential for analyzing the wind turbine performance located in the built environment. In this work, the building layout like nozzle is proposed and the objective is to optimize the building layout for increasing electrical energy output of wind turbine, assumed to be installed in actual cities of Japan. The wind speed distribution across buildings is numerically simulated by using CFD-ACE+. Wind turbine power output is estimated using the power curve of a real commercial wind turbine and wind speed distribution is simulated using CFD software. The meteorological data of Fukushima city and Tsu city of Japan are utilized for evaluating the wind speed distribution profile across the building and for finding the electrical energy output from wind turbine. The proposed building models, which have the angle between two buildings like nozzle of 90°, 135° and 180°, can provide the wind acceleration at the back of buildings for the wind blowing from the main wind direction and the angle of 135°is optimum building layout. In the case of installing the proposed building model in Fukushima city and Tsu city, the wind energy output in winter season is higher while that in summer season is lower irrespective of the buildings’ angle. The interaction between the change in frequency distribution of wind speed and direction throughout the year and the location of open tip of building model decides the power generation characteristics of the proposed building model.

Smart Grid for a Sustainable Future

Advances in micro-electro-mechanical systems (MEMS) and information communication technology (ICT) have facilitated the development of integrated electrical power systems for the future. A recent major issue is the need for a healthy and sustainable power transmission and distribution system that is smart, reliable and climate-friendly. Therefore, at the start of the 21st Century, Government, utilities and research communities are working jointly to develop an intelligent grid system, which is now known as a smart grid. Smart grid will provide highly consistent and reliable services, efficient energy management practices, smart metering integration, automation and precision decision support systems and self healing facilities. Smart grid will also bring benefits of seamless integration of renewable energy sources to the power networks. This paper focuses on the benefits and probable deployment issues of smart grid technology for a sustainable future both nationally and internationally. This paper also investigates the ongoing major research programs in Europe, America and Australia for smart grid and the associated enabling technologies. Finally, this study explores the prospects and characteristics of renewable energy sources with possible deployment integration issues to develop a clean energy smart grid technology for an intelligent power system.

Simulation the Wind Grid Code Requirements for Wind Farms Connection in Kosovo Transmission Grid

This paper presents aspects of study and simulation approach for planned wind power projects in Kosovo Power System in relation with Grid Code requirements. All generators, connected to the Kosovo Transmission System are required to comply with the Grid Code. The Grid Code was originally developed with conventional synchronous generators. Since Wind Turbine Generators don’t have the same characteristics as synchronous generators, it was considered appropriate to develop a new set of Grid Code provisions specifically for Wind Farm Power Stations in relation with specific characteristic of Kosovo Power System. With high excepted penetration of wind power, a simultaneous loss of Wind Farms generation will put in the risk the security and reliability of Power System. Therefore, the main requirements for Wind farm power stations concern the fault ride through capability, frequency operation range, and reactive power capability of wind turbines. In the case of grid faults wind turbines have to supply a definite reactive power depending on the instantaneous voltage level of connection point and they must return quickly to normal operation.

Impact of Wind Energy System Integration on the Al-Zawiya Refinery Electric Grid in Libya

Libya is an oil exporting country located in the middle of the North Africa. Exporting oil is the major income resource for the economics of the country. Al-Zawea refinery is one of the oil refineries in Libya. It is the largest refinery in the region. The refinery located in the Mediterranean coast. Electricity is the main sector in the refinery to produce and export oil. This paper discusses the possibility of the penetration of the renewable energy (wind) generated electricity into the refinery power system. Although, renewable energy application in Libya was started in the middle of the seventies, it has still not found its way into industry sector. This study proposes the possible impacts of renewable (wind) energy system integration on the Al-Zawea refinery electric grid to satisfy the refinery load demand.

New “Intellectual Networks” (Smart Grid) for Detecting Electrical Equipment Faults, Defects and Weaknesses

The most important elements of “intellectual networks” (Smart Grid) are the systems of monitoring the parameters of electrical equipment. Information-measuring systems (IMS), which described in this paper, were proposed to use together with rapid digital protection against short-circuit regimes in transformer windings. This paper presents an application’s experience of LVI-testing, some results of the use of Frequency Response Analysis (FRA) to check the condition of transformer windings and infra-red control results of electrical equipment. The LVI method and short-circuit inductive reactance measurements are sensitive for detecting such faults as radial, axial winding deformations, a twisting of low-voltage or regulating winding, a losing of winding’s pressing and others.

Fuzzy Logic Controlled Dual Active Bridge Series Resonant Converter for DC Smart Grid Application

Over the last few years, smart grids have become a topic of intensive research, development and deployment across the world. This is due to the fact that, through the smart grid, stable and reliable power systems can be achieved. This paper presents a fuzzy logic control for dual active bridge series resonant converters for DC smart grid application. The DC smart grid consists of wind turbine and photovoltaic generators, controllable and DC loads, and power converters. The proposed control method has been applied to the controllable load＇s and the grid side＇s dual active bridge series resonant converters for attaining control of the power system. It has been used for management of controllable load＇s state of charge, DC feeder＇s voltage stability during the loads and power variations from wind energy and photovoltaic generation and power flow management between the grid side and the DC smart grid. The effectiveness of the proposed DC smart grid operation has been verified by simulation results obtained by using MATLAB and PLECS cards.

Use of Renewable Energy Sources in Saudi Arabia through Smart Grid

Even though Saudi Arabia is the world＇s largest producer and exporter of petroleum and petroleum based products, it is also blessed with high potential of renewable energy sources like solar and wind. Untapped wind and solar energy sources, which are abundant throughout the kingdom, can be connected and optimally integrated into the grid through the use of smart grid technologies and the expansion of transmission facilities. Smart grid is an auto-balancing, self-monitoring power grid that accepts power from any source of fuel like oil, sun or wind and delivers electricity from suppliers to consumers. It helps to control the use of appliances in order to save energy, reduces cost and increase reliability. This paper describes the attributes of a smart grid and how these act as driving force to modernize the electrical power grid. The necessity of conservation of oil in Saudi Arabia is argued. Moreover, the vast availability of renewable energy sources like solar and wind in Saudi Arabia and advantages in utilizing these sources through smart grid technologies are advocated in this paper.

CFD simulations targeting the performance of the NTNU BT1 wind turbine using overset grids

In the present study, the performance of the NTNU Blind Test 1 wind turbine is analyzed in the computational fluid dynamics (CFD) simulations by using the CFD code FANS with structured overset grids. First, the numerical methods including the governing equations, the turbulence closure model, and the flow solver are introduced. In addition, the NTNU BT1 wind tunnel experiment is described. Then, structured overset grid blocks are generated in the computational domain with fully resolved wind turbine geometry, including the blades, hub, nacelle, and tower. Afterward, unsteady Reynolds averaged Navier-Stokes (RANS) simulations with the two-layer k - ε turbulence model are performed with an inlet velocity of 10 m/s and a tip-speed ratio (TSR) of 6. The overset-grid capability of FANS is leveraged to handle the rotation of the rotor. Finally, simulations are performed for a range of TSRs and a comparison is made among the present CFD results, other numerical results obtained from representative methods, and the experimental data. It is observed that the CFD-predicted thrust coefficients match the experimental measurement at low TSRs while under-predicting the values at high TSRs, and potential reasons for this deviation are discussed.

Effect of Climate Change on Transformers Loading Conditions in the Future Smart Grid Environment

The steady-state calculations are performed using IEC guidelines to determine the hot spot temperatures of distribution and power transformers in the worst projected Finnish environment due to long summer periods. Moreover, the effect of increase in winding resistance due to increase in ambient temperatures has been taken into account. The primary objective of the research is to investigate the possible extreme circumstances due to climate change. It is concluded that the power and distribution transformers should be progressively de-rated under such circumstances for their safe operations, which will not only prove cost-effective for utilities but also improve the reliability of the power supply to their valued customers in the challenging future smart grid environment.

不对称短路故障下永磁直驱风电机组并网控制策略研究

电网侧发生不对称故障时,永磁直驱风电机组并网电流会发生三相不平衡的问题。针对这一问题,提出一种基于自适应陷波器的网侧换流器控制策略。该控制策略基于解决机组并网电流二倍频分量的思想,在电网侧发生不对称短路故障时,将进入逆变器的dq坐标系下的二倍频电压分量去除,从而使得网侧换流器输出的电流达到三相平衡。本文首先分析了电网侧发生不对称短路故障后永磁直驱风力发电机组的动态响应;然后建立了机侧和网侧换流器的模型,并分别采用了双闭环矢量控制技术和基于自适应陷波器的控制策略;最后进行仿真分析,验证了改进后的控制策略相较于传统控制策略,有效解决了不对称短路故障下并网电流三相不平衡问题。