Resonance Stability Analysis of Large-Scale Wind Power Bases with Type-IV Wind Generators

To guarantee the reliable and efficient development of wind power generation, oscillation problems in large-scale wind power bases with Type-IV generators are investigated from the view of resonance stability in this paper. Firstly, the transfer characteristics of disturbances in Type-IV wind generators are analyzed to establish their impedance model, based on the balance principle of frequency components. Subsequently, considering the dynamic characteristics of the transmission network and the interaction among several wind farms, the resonance structure of a practical wind power base is analyzed based on the s-domain nodal admittance matrix method. Furthermore, the unstable mechanism of the resonance mode is further illustrated by the negative-resistance effect theory. Finally, the established impedance model of the Type-IV wind generator and the resonance structure analysis results of the wind power bases are verified through the time-domain electro-magnetic transient simulation in PSCAD/EMTDC. Case studies indicate that there is a certain resonance instability risk in large-scale wind power bases in a frequency range of 1–100 Hz, and the unstable resonance mode is strongly related to the negative-resistance effect and the capacitive effect of Type-IV wind generators.

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Performance Enhancement of Proposed Namaacha Wind Farm by Minimising Losses Due to the Wake Effect: A Mozambican Case Study

Energies ◽

10.3390/en14144291 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4291

Author(s):

Paxis Marques João Roque ◽

Shyama Pada Chowdhury ◽

Zhongjie Huan

Keyword(s):

Wind Speed ◽

Wind Power ◽

Wind Turbines ◽

Power Output ◽

Wind Farm ◽

Wind Farms ◽

Operating Conditions ◽

Wake Effect ◽

Wind Generators ◽

Wind Potential

District of Namaacha in Maputo Province of Mozambique presents a high wind potential, with an average wind speed of around 7.5 m/s and huge open fields that are favourable to the installation of wind farms. However, in order to make better use of the wind potential, it is necessary to evaluate the operating conditions of the turbines and guide the independent power producers (IPPs) on how to efficiently use wind power. The investigation of the wind farm operating conditions is justified by the fact that the implementation of wind power systems is quite expensive, and therefore, it is imperative to find alternatives to reduce power losses and improve energy production. Taking into account the power needs in Mozambique, this project applied hybrid optimisation of multiple energy resources (HOMER) to size the capacity of the wind farm and the number of turbines that guarantee an adequate supply of power. Moreover, considering the topographic conditions of the site and the operational parameters of the turbines, the system advisor model (SAM) was applied to evaluate the performance of the Vestas V82-1.65 horizontal axis turbines and the system’s power output as a result of the wake effect. For any wind farm, it is evident that wind turbines’ wake effects significantly reduce the performance of wind farms. The paper seeks to design and examine the proper layout for practical placements of wind generators. Firstly, a survey on the Namaacha’s electricity demand was carried out in order to obtain the district’s daily load profile required to size the wind farm’s capacity. Secondly, with the previous knowledge that the operation of wind farms is affected by wake losses, different wake effect models applied by SAM were examined and the Eddy–Viscosity model was selected to perform the analysis. Three distinct layouts result from SAM optimisation, and the best one is recommended for wind turbines installation for maximising wind to energy generation. Although it is understood that the wake effect occurs on any wind farm, it is observed that wake losses can be minimised through the proper design of the wind generators’ placement layout. Therefore, any wind farm project should, from its layout, examine the optimal wind farm arrangement, which will depend on the wind speed, wind direction, turbine hub height, and other topographical characteristics of the area. In that context, considering the topographic and climate features of Mozambique, the study brings novelty in the way wind farms should be placed in the district and wake losses minimised. The study is based on a real assumption that the project can be implemented in the district, and thus, considering the wind farm’s capacity, the district’s energy needs could be met. The optimal transversal and longitudinal distances between turbines recommended are 8Do and 10Do, respectively, arranged according to layout 1, with wake losses of about 1.7%, land utilisation of about 6.46 Km2, and power output estimated at 71.844 GWh per year.

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A Self-Regulation Strategy for the Power Fluctuation of the Islanded Voltage Source Converter (VSC) Station Delivering Large-Scale Wind Power

Energies ◽

10.3390/en13030560 ◽

2020 ◽

Vol 13 (3) ◽

pp. 560

Author(s):

Juanjuan Sun ◽

Hui Wang ◽

Xiaomin Zhu ◽

Qian Pu

Keyword(s):

Wind Power ◽

Large Scale ◽

Self Regulation ◽

Wind Farms ◽

The Self ◽

Voltage Source ◽

Time Variability ◽

Frequency Regulation ◽

Voltage Source Converter ◽

Power Fluctuation

When the power source of a voltage source converter (VSC) station at the sending end solely depends on wind power generation, the station is operating in an islanding mode. In this case, the power fluctuation of the wind power will be entirely transmitted to the receiving-end grid. A self-regulation scheme of power fluctuation is proposed in this paper to solve this problem. Firstly, we investigated the short-time variability characteristic of the wind power in a multi-terminal direct-current (MTDC) project in China. Then we designed a virtual frequency (VF) control strategy at the VSC station based on the common constant voltage constant frequency (CVCF) control of VSC station. By cooperating with the primary frequency regulation (PFR) control at the wind farms, the self-regulation of active power pooling at the VSC station was realized. The control parameters of VF and PFR control were carefully settled through the steady-state analysis of the MTDC grid. The self-regulation effect had been demonstrated by a twenty-four-hour simulation. The results showed that the proposed scheme could effectively smoothen the power fluctuation.

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A Wind-Thermal Hydropower Coordination Control Strategy Based on Multiple Constraints of Large-Scale Wind Power Integration

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.724-725.463 ◽

2013 ◽

Vol 724-725 ◽

pp. 463-468

Author(s):

Jian Bo Wang ◽

Wen Ying Liu ◽

Wei Zheng ◽

Chen Liang

Keyword(s):

Wind Power ◽

Control Strategy ◽

Large Scale ◽

Thermal Power ◽

Wind Farms ◽

System Stability ◽

Maximum Output ◽

Multiple Constraints ◽

Operating Characteristics ◽

Output Constraints

Due to the fluctuations and intermittency of wind power, large-scale wind farms integration will cause adverse impact on the safety and stability of the system,such as harmonic pollution, bad power quality, system stability destruction.On the basis of multiple constraints, including hydropower’s and thermal power’s operating characteristics, determination of reserve capacity considering wind power forecasting bias, climbing speed constraints, and maximum output constraints, this paper proposed a control strategy of joint coordination of wind, hydropower and thermal power, which suppressed the fluctuations of wind power effectively. At last, the article give a simulation to verify the feasibility of the control strategy to stabilize system frequency.

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Mechanism Research about Impact of Large-Scale Wind Power Integration on Grid Loss

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1070-1072.200 ◽

2014 ◽

Vol 1070-1072 ◽

pp. 200-203

Author(s):

Ze Tian Wei ◽

Wen Ying Liu ◽

Fu Chao Liu ◽

Jian Zong Zhuo

Keyword(s):

Wind Power ◽

Transmission Lines ◽

Power Flow ◽

Large Scale ◽

Wind Farms ◽

Active Power ◽

Equivalent Model ◽

Factors Affecting ◽

Main Factors ◽

Grid Loss

This paper firstly analyzes the mechanism of transmission line and transformer loss and illustrates the equivalent model and calculating method. Then creates a simple three-node model and discusses the main factors which affect the grid loss with adequate formula. At last, we draw a concise conclusion that there are several factors affecting grid loss. The main factors are the location of wind power access, the active power flow of transmission lines, the active power output of wind farms and the voltage level of wind power access.

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A Coherency-Based Equivalent Model of a Large Scale Wind Farm

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.347-353.2342 ◽

2011 ◽

Vol 347-353 ◽

pp. 2342-2346

Author(s):

Rong Fu ◽

Bao Yun Wang ◽

Wan Peng Sun

Keyword(s):

Wind Power ◽

Wind Turbines ◽

Large Scale ◽

Wind Farm ◽

Dynamic Models ◽

Wind Farms ◽

Model Complexity ◽

Equivalent Model ◽

Detailed Model ◽

Doubly Fed

With increasing installation capacity and wind farms penetration, wind power plays more important role in power systems, and the modeling of wind farms has become an interesting research topic. In this paper, a coherency-based equivalent model has been discussed for the doubly fed induction generator (DFIG). Firstly, the dynamic models of wind turbines, DFIG and the mechanisms are briefly introduced. Some existing dynamic equivalent methods such as equivalent wind model, variable speed wind turbine model, parameter identification method and modal equivalent method to be used in wind farm aggregation are discussed. Then, considering wind power fluctuations, a new equivalent model of a wind farm equipped with doubly-fed induction generators is proposed to represent the interactions of the wind farm and grid. The method proposed is based on aggregating the coherent group wind turbines into an equivalent one. Finally, the effectiveness of the equivalent model is demonstrated by comparison with the wind farm response obtained from the detailed model. The dynamic simulations show that the present model can greatly reduce the computation time and model complexity.

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Two methods for estimating limits to large-scale wind power generation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1408251112 ◽

2015 ◽

Vol 112 (36) ◽

pp. 11169-11174 ◽

Cited By ~ 32

Author(s):

Lee M. Miller ◽

Nathaniel A. Brunsell ◽

David B. Mechem ◽

Fabian Gans ◽

Andrew J. Monaghan ◽

...

Keyword(s):

Power Generation ◽

Kinetic Energy ◽

Wind Power ◽

Energy Flux ◽

Wind Turbines ◽

Large Scale ◽

Wind Farms ◽

Wind Power Generation ◽

Flux Method ◽

Free Atmosphere

Wind turbines remove kinetic energy from the atmospheric flow, which reduces wind speeds and limits generation rates of large wind farms. These interactions can be approximated using a vertical kinetic energy (VKE) flux method, which predicts that the maximum power generation potential is 26% of the instantaneous downward transport of kinetic energy using the preturbine climatology. We compare the energy flux method to the Weather Research and Forecasting (WRF) regional atmospheric model equipped with a wind turbine parameterization over a 105 km2 region in the central United States. The WRF simulations yield a maximum generation of 1.1 We⋅m−2, whereas the VKE method predicts the time series while underestimating the maximum generation rate by about 50%. Because VKE derives the generation limit from the preturbine climatology, potential changes in the vertical kinetic energy flux from the free atmosphere are not considered. Such changes are important at night when WRF estimates are about twice the VKE value because wind turbines interact with the decoupled nocturnal low-level jet in this region. Daytime estimates agree better to 20% because the wind turbines induce comparatively small changes to the downward kinetic energy flux. This combination of downward transport limits and wind speed reductions explains why large-scale wind power generation in windy regions is limited to about 1 We⋅m−2, with VKE capturing this combination in a comparatively simple way.

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Study on Loss Reduction of Large Scale Wind Power Concentrated Integration on Power System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.380-384.3051 ◽

2013 ◽

Vol 380-384 ◽

pp. 3051-3056 ◽

Cited By ~ 2

Author(s):

Xiao Dan Wu ◽

Wen Ying Liu

Keyword(s):

Power System ◽

Wind Power ◽

Power Loss ◽

Large Scale ◽

Wind Farm ◽

Reactive Power ◽

Low Voltage ◽

Main Step ◽

Loss Reduction ◽

Wind Generators

In this paper, starting from the active network loss formulas and wind characteristics, it is pointed out the reactive power loss and reactive flow is the major impact of wind power integration on power system loss. The reactive power loss formulas of box-type transformer, main step-up transformer, wind farm collector line and connecting grid line are analyzed. Next the reactive power loss of transformer and transmission line is described in detail. Then put forward the loss reduction measures that installing SVC on the low voltage side of the main step-up transformer and making the doubly-fed wind generators send out some reactive power at an allowed power factor. Use the case of Gansu Qiaodong wind farm to verify the effectiveness of the proposed measures.

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M2GSNet: Multi-Modal Multi-Task Graph Spatiotemporal Network for Ultra-Short-Term Wind Farm Cluster Power Prediction

Applied Sciences ◽

10.3390/app10217915 ◽

2020 ◽

Vol 10 (21) ◽

pp. 7915

Author(s):

Hang Fan ◽

Xuemin Zhang ◽

Shengwei Mei ◽

Kunjin Chen ◽

Xinyang Chen

Keyword(s):

Wind Power ◽

Large Scale ◽

Wind Farm ◽

Weather Prediction ◽

Wind Farms ◽

Task Graph ◽

Probabilistic Prediction ◽

Power Prediction ◽

Short Term ◽

Wind Power Prediction

Ultra-short-term wind power prediction is of great importance for the integration of renewable energy. It is the foundation of probabilistic prediction and even a slight increase in the prediction accuracy can exert significant improvement for the safe and economic operation of power systems. However, due to the complex spatiotemporal relationship and the intrinsic characteristic of nonlinear, randomness and intermittence, the prediction of regional wind farm clusters and each wind farm’s power is still a challenge. In this paper, a framework based on graph neural network and numerical weather prediction (NWP) is proposed for the ultra-short-term wind power prediction. First, the adjacent matrix of wind farms, which are regarded as the vertexes of a graph, is defined based on geographical distance. Second, two graph neural networks are designed to extract the spatiotemporal feature of historical wind power and NWP information separately. Then, these features are fused based on multi-modal learning. Third, to enhance the efficiency of prediction method, a multi-task learning method is adopted to extract the common feature of the regional wind farm cluster and it can output the prediction of each wind farm at the same time. The cases of a wind farm cluster located in Northeast China verified that the accuracy of a regional wind farm cluster power prediction is improved, and the time consumption increases slowly when the number of wind farms grows. The results indicate that this method has great potential to be used in large-scale wind farm clusters.

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Urban Wind: Effects of Structural Geometry

Volume 6B: Energy ◽

10.1115/imece2014-38658 ◽

2014 ◽

Author(s):

M. Grayson ◽

E. Garcia

Keyword(s):

Wind Power ◽

Urban Areas ◽

Large Scale ◽

Separation Bubble ◽

Flow Behavior ◽

Leading Edge ◽

Wind Farms ◽

Flow Region ◽

Accelerated Flow ◽

Energy Harvesting Devices

Wind power continues to be produced by large-scale wind farms in remote areas. Supplying urban areas requires that this power be transmitted over vast distances. Generating power locally in urban cities not only decreases transmission distances but reduces external demand by using the harvested energy on site. A crucial element in the use of wind in the built environment as a source of energy is finding ways to maximize its flow. As flow approaches the windward façade of a building’s structure, it is disturbed, causing an increase in velocity both at the roof’s edge and above the separation bubble. Energy harvesting devices are usually placed in this flow region. The aim of this study is to further investigate the accelerated flow by modifying the building’s structure to be a concentrator of the wind, thereby maximizing the available wind power. Using computational fluid dynamics, sloped façades at varying angles were investigated. Simulations show that at an angle of 30°, the velocity is amplified by more than 100% at the separation point directly above the roof’s leading edge. Currently, wind tunnel experiments simulating flow behavior are being conducted and it is expected that analysis of the data will validate and support the findings presented.

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Research on Transient Stability of Wind Farms Based on Coordinated System of SVS and STATCOM

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.740.397 ◽

2015 ◽

Vol 740 ◽

pp. 397-400

Author(s):

Min Rui Qiao ◽

Lin Lin Wu ◽

Yue Qiao Li

Keyword(s):

Wind Power ◽

Large Scale ◽

Transient Stability ◽

Reactive Power ◽

Wind Farms ◽

Single Type ◽

Photovoltaic Systems ◽

Wind Power Integration ◽

Rapid Reaction ◽

And Performance

As large-scale wind farms are connected to the grid, a single type compensator cannot meet the demand. STATCOM has ability of rapid reaction and harmonics suppression, SVC can compensate large capacity reactive power. In this study, a compensator, which is able to coordinate Static Var System (SVS) with STATCOM is proposed. Large-scale wind power integration is simulated respectively with the compensator of STATCOM alone and coordinated compensator of SVS and STATCOM by DIgSILENT/Powerfactory15.0. Simulations results clearly verify that the compensator of SVS and STATCOM improves transient stability and performance of the photovoltaic systems.

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