Valerijs Bezrukovs

Comparative efficiency of wind turbines with different heights of rotor hubs: performance evaluation for Latvia

Performance evaluation of wind turbines (WT) for different heights of the rotor hub is made based on the wind speed and direction data obtained in 2009–2013 on-shore in the north of Latvia using a LOGGER 9200 Symphonie measurement system mounted on a 60 m mast. Based on the measurement analysis results, wind speed distribution curves have been modelled for heights of up to 200 m using power and logarithmic (log) law approximation methods. The curves for the modelled Weibulls parameters are plotted in dependence on height. The efficiency comparison is made for different WT types taking into account the distribution of the wind energy potential in height in the Latvian territory. The annual electric energy production was calculated for the WTs with different heights of rotor hubs. In the calculations the technical data on the following WT types were used: E-3120 (50 kW, hub height 20.5/30.5/36.5/42.7 m), E-33 (330 kW, hub height 37/44/49/50 m), E-48 (800 kW, hub height 50/60/75 m) and E-82 (2.3 MW, hub height of 78/85/98/108/138 m).

Web application for processing and analysis of the raw wind measurement data

In light of recent geopolitical events renewable energy topic is being extensively discussed and negotiated on state and EU level. Wind farms are sustainable source of renewable energy with relatively low service costs in long term planning. Recent investigations confirm economic benefit of deploying wind farms in Baltic region. General requirement for wind energy sector development is availability of reliable information about wind conditions in the region for long time period and access to appropriate modeling and analysis tools. In a scope of wind energy assessment project authors are measuring plenty of wind parameters in region and performing analysis of obtained information. Paper describes developed Web application used for retrieving data from various sources in semiautomated way with subsequent centralized processing, analysis and report development.

Analysis of Wind Influence to Radio Astronomy Observations at Irbene Radio-telescope Complex

Analysis of Wind Influence to Radio Astronomy Observations at Irbene Radio-telescope Complex The results of modelling wind-related deformations in an RT-16 radio telescope (located at Irbene, Latvia) mirror system are presented. The Finite Volume method is used for the development of a Computational Fluid Dynamic model of turbulent airflow around the telescope. An open sourced Computational Fluid Dynamic toolkit OpenFOAM is used for the solution of Partial Different Equations. Notable model difficulties arise due to the open nature of the air flow leading to unknown far field turbulence parameters. Our future plans are to create a unified, coupled, liquid-solid interaction model for RT-32/RT-16 antennas. Vēja ietekmes analīze uz radioastronomiskajiem novērojumiem Irbenes radioteleskopu kompleksā Izpēte veikta Irbenē, Ventspils Augstskolas radioastronomijas centrā, kurā darbojas divi paraboliski radioteleskopi - RT-32 (32 m augsta antena ar virsmas laukumu 800 m2) un RT-16 (16 m augsta antena ar virsmas laukumu 201 m2). Centrā jau kopš 2007. gada tiek veikta radioteleskopa RT-16 spoguļa sistēmas deformāciju modelēšana un tiek vākti statistikas dati par vēja ātrumu, izmantojot meteorologisko torni observatorijas tuvumā. Radioastronomiskie pētījumi ir ļoti jūtīgi pret virsmas precizitāti, pat nelielas deformācijas var ievērojami samazināt antenu veiktspēju. Radioteleskopa konstrukcijas skar dažāda veida slodzes: gravitāte, vējš un temperatūras svārstības. Šajā publikācijā tiek analizēti rezultāti, kas iegūti modelējot vēja radītās deformācijas uz RT-16 radioteleskopa spoguļa sistēmu. Lai modelētu turbulentu gaisa plūsmu ap teleskopu, tiek izmantots skaitliskās hidrodinamik as (Computational Fluid Dynamic) modelis un galīgo tilpumu metode. Parciālo diferenciālvienādojumu risin āšanai tika pielietots atvērtā koda skaitliskās hidrodinamikas instruments OpenFOAM. Aprēķini tika veikti, novietojot teleskopa spoguli dažādos leņķos. Modeļa sarežgītība slēpjas apstāklī, ka tiek apskatīta turbulenta gaisa plūsma. Šajā izpētē turbulentajai plūsmai bija relatīvi zems ātrums, līdz ar to gaisa blīvums saglabājās praktiski nemainīgs. Turpmāk tiek plānots izveidot vienotu hidrodinamikas un cietvielu modeli gan RT-16, gan RT-32 antenai.

Simulation of the Flow Field over the Coastal Terrain

This work presents the preliminary study of simulations of the atmospheric boundary layer over the coastal terrain. The Reynolds-averaged Navier–Stokes equations approach is applied to numerical modelling. The primary goal of the research is to assess the value of wind speed changes due to ground topography at planned measurement place near the sea coast. The simulations of the airflow have been done using the OpenFOAM open source software. The influence of the turbulence models, the dimensions of the computational domain and the mesh size on predicted wind speed is investigated.

Forecasting of wind turbine efficiency in Latvia by long-term wind speed measurements

The paper presents the assessment of power production efficiency of five wind turbine generator types in low-wind conditions typical for Latvia. The analysis considers wind turbines manufactured by the leading European producers - Nordex, Vestas, Enercon and Siemens. The study is based on 10-min measurements of wind speed from two on-shore sites in the north and north-west of Latvia using LOGGER 9200 Symphonie measurement systems mounted on met-masts. Based on the measurement analysis results, wind speed distribution curves are modelled for the heights of up to 150 m using power law approximation methods. The forecast of Annual Energy Production (AEP) is performed using the Weibull frequency distribution of wind speed for two heights for each corresponding wind turbine type. The results of the analysis show that the highest output efficiency can be achieved by Vestas and Nordex wind turbines, which power curves correspond to wind class III. Vestas V136-3.45 with hub height 132 m achieves maximum efficiency equal to 54.5% in Irbene site. For Enercon E101 and Siemens SWT-3.2-113, SWT-2.3-108 WTs, which are designed for wind class II, the values of the efficiency coefficient do not exceed 47.3% for hub height 142 m.