Large Wind Parks Research Articles

Determining onshore or offshore hydrogen storage for large offshore wind parks: The North Sea Wind Power Hub case

The large-scale integration of renewable energy sources leads to daily and seasonal mismatches between supply and demand and the curtailment of wind power. Hydrogen produced from surplus wind power offers an attractive solution to these challenges. In this paper, we consider a large offshore wind park and analyze the need for hydrogen storage at the onshore and offshore sides of a large transportation pipeline that connects the wind park to the mainland. The results show that the pipeline with line pack storage, though important for day-to-day fluctuations, will not offer sufficient storage capacity to bridge seasonal differences. Furthermore, the results show that if the pipeline is sufficiently sized, additional storage is only needed on one side of the pipeline, which would limit the needed investments. Results show that the policy which determines what part of the wind power is fed into the electricity grid and what part is converted into hydrogen has a significant influence on these seasonal storage needs. Therefore, investment decisions for hydrogen systems should be made by considering both the onshore and offshore storage requirements in combination with electricity transport to the mainland.

BISTATIC SCATTERING CHARACTERISTICS OF A WIND PARK TURBINE DERIVED FROM AN UAV-MOUNTED RECEIVER RECORDING C-BAND WEATHER RADAR SIGNALS

Abstract. As a result of increasing use of wind energy as a sustainable source of electricity, large Wind Parks with numerous Wind Turbines have been constructed. Wind turbines are extremely tall objects consisting of stationary and moving parts. The presence of wind turbines in the vicinity of weather radar systems can significantly impact their performance, leading to false alarms and errors in radar measurements. Accurate weather forecasting is challenging in this circumstance. Large Radar Cross Section (RCS) of wind turbines results in interference, also known asWind Turbine Clutter (WTC) orWind Turbine Interference (WTI), within and beyond the radar main beam, Multipath Interference (MPI), and phenomena referred to as ”shadowing effects” behind the wind turbines. These effects vary significantly in both time and space as a result of various wind turbine operations and meteorological conditions. It can often be difficult to distinguish wind turbine returns from weather-like signals. For the assessment of WTC or WTI, it is essential to understand the scattering properties of these wind turbines. In this paper, the bistatic scattering characteristics of a wind park turbine using a Unmanned Aerial Vehicle (UAV)-mounted receiver recording C-band weather radar signals were investigated by determining the average received power (PRxAvg (θs)) and RCS of wind turbine as a function of the scattering angle. For this purpose, the measurements and data provided by the German Meteorological Service (DWD, DeutscherWetterdienst) were utilised. The average received power as a function of scattering angle (θs) was calculated by using I-Q (In-phase and Quadrature) signals. Forward, back and side scattering of the calculated average received power were analysed separately. Moreover, Front-to-Back ratio, Front-to-Right side ratio and Front-to-Left side ratio were calculated and compared using forward, back and side scatter values. RCS values were also calculated depending on the scattering angle (θs) of the wind turbine.

Unlocking the Hidden Capacity of the Electrical Grid Through Smart Transformer and Smart Transmission

Power systems are experiencing a rapid and dramatic transformation driven by the massive integration of nondispatchable renewable energy sources, such as wind and solar, and highly variable loads, such as electric vehicles and air conditioning. This challenges existing grid assets, eventually leading to updating them, which, in turn, increases significantly the costs of sustainable technologies. Power electronics is a pivotal technology for electrical power processing for renewable energies and sustainable transportation. By means of “smart” functionalities, power electronics converters already embedded in such applications can also contribute to guaranteeing the overall system’s stable operation. Anyway, this cooperative contribution from distributed devices may be not enough leading to the need for the voltage transformation and power transmission of “system-level” power electronics solutions. In the case of large charging stations, a smart transformer (ST), while, in the case of large solar and wind parks, integration medium- or high-voltage direct current (HVdc) transmissions are system-level solutions. This article wants to review the potential of using such infrastructures to increase the capacity of existing grid assets, avoiding or deferring their upgrade and, hence, reducing the overall costs of renewables integration and the electrification of the transport sector. In fact, the power converters embedded in ST and HVdc can provide fast frequency and voltage response, and precise control of power flow acting at the system level much more effectively and feasibly for system operators as the distributed power converters embedded in several small sources and users. This article reviews, for the first time, these two key power electronics “system-level” solutions together—ST and HVdc—starting from their basic functionalities and showings how they can go beyond them, showing how, with grid-forming functionalities, they can offer new “smart grid” tools to enhance the capability of the existing electric grid infrastructures.

An intelligent and automatic control of renewable production for flexible access of large offshore wind parks

The paper presents an automatic active power modulation control that has been developed and implemented to handle the potential overload that can appear in case of loss of one or more of the export cables of the Modular Offshore Grid (MOG) installed in the Belgian Coastal Area. The automatic controller, implemented in the Energy Management System (EMS) of ELIA sends setpoints of active power to the different wind parks, that have a total installed power of 1 GW taking into account not only the current and potential future topology (i.e. potential additional incidents) and the forecast of ampacity calculated by a Real Time Thermal Rating system installed on the cables. The robustness and reliability of the system has been enhanced with the addition of dynamic alarms, automatic detection of non-compliant control actions from the parks and a local backup protection that disconnects automatically the cables in case of prolonged unacceptable overload.

Condition Assessment of HVDC Cables during their Lifecycle

Recent market developments towards power generation in remote renewable power plants such as concentrated solar power plants in deserts or large off-shore wind parks, raise an interest for long distance power transmission via extruded HVDC cables. HVDC cables require quality assurance during the complete product lifecycle, mainly: a) R&D activities for design verification and - validation b) routine tests in the factory for confirmation of proper manufacturing c) acceptance test after erection and commissioning to exclude defects caused during transport and installation d) ageing monitoring and quick fault detection and location detection during service life. Considering increasing voltage levels, increasing cable lengths and ground or even offshore installation, the dielectric testing of extruded HVDC cables in the factory and on site remains challenging. The long-term validation of insulation coordination requires high voltages for quality assurance tests which represent typical expectable stresses during service. Typical examples are wave shape, partial discharge behavior and dielectric field stress in the insulation medium. Hence, different technical solutions are available to generate these required high voltages for testing of HVDC cables. This paper discusses essential technical and commercial aspects of HVDC cable quality assurance and presents suitable methods for HVDC cable testing.

Multicriteria Decision Aiding for Planning Renewable Power Production at Moroccan Airports

This study is about multicriteria decision aiding (MCDA) for the green airports program of the Moroccan Airport Authority ONDA. The goal of the program is to develop significant amounts of renewable power at airports. In particular, ONDA wants to select airports at which large solar and wind power parks should be built. Multiple criteria, including economy, technical feasibility, and environmental concerns, must be considered simultaneously. In this study, we apply Stochastic Multicriteria Acceptability Analysis (SMAA) for ranking the candidates to be developed into green airports. The analysis is conducted in phases with different sets of criteria. This study is the first application of MCDA for developing large-scale renewable energy production at airports. As a theoretical novelty, the pairwise winning indices of SMAA are used to form stochastic partial and complete rankings of the alternatives. Based on the results, two alternatives obtain the best and second-best rank in every model, and one alternative is always last, while the ranks of the remaining alternatives vary depending on the set of criteria.

Long-range modifications of the wind field by offshore wind parks – results of the project WIPAFF

This publication synthesizes the results of the WIPAFF (WInd PArk Far Fields) project. WIPAFF focused on the far field of large offshore wind park wakes (more than 5 km downstream of the wind parks) located in the German North Sea. The research project combined in situ aircraft and remote sensing measurements, satellite SAR data analysis and model simulations to enable a holistic coverage of the downstream wakes. The in situ measurements recorded on-board the research aircraft DO-128 and remote sensing by laser scanner and SAR prove that wakes of more than 50 kilometers exist under certain atmospheric conditions. Turbulence occurs at the lateral boundaries of the wakes, due to shear between the reduced wind speed inside the wake and the undisturbed flow. The results also reveal that the atmospheric stability plays a major role in the evolution of wakes and can increase the wake length significantly by a factor of three or more. On the basis of the observations existing mesoscale and industrial models were validated and updated. The airborne measurement data is available at PANGAEA/ESSD.

Assessment of frequency performance by wind integration in a large‐scale power system

AbstractLarge‐scale grid integration of wind energy particularly in the southeastern portion of the Mexican interconnected power system has affected available transfer capability and imposed additional uncertainty on power system operation. Integrating large amounts of wind energy into the system is challenging because of the variability in power system dynamics and a more complex active and reactive power dispatch.Wind plants have been installed in the Mexican systems during the past few years. The total installed wind energy capacity of the system is around 2.5 GW; the total wind energy generation represents 4% of current installed generation in the Mexican system. Increase of the wind power is expected to have an impact on power system control and transient behavior, especially as the amount of wind generation represents a significant portion of the local generation and wind farms grow in size and complexity.Using recent planning and operation wind data, detailed studies on the effects of new wind generation on power system dynamic behavior are carried out. Analyses of the dynamic impact of large wind parks on power system dynamic performance are conducted. Operating impact studies include frequency behavior and the response of wind farms to major disturbances.Simulation studies on a realistic 4000‐bus dynamic model of the Mexican interconnected system show that large wind generating plants have a significant effect on system dynamic behavior.

On the Efficient Calculation of the Periodic Steady-State Response of Grid-Connected Wind Parks—Part I

This paper presents a new power systems simulation environment suitable for the swift calculation of the periodic steady-state response of large power networks with large wind parks. In order to achieve the greatest computational efficiency and solution reliability, the wind generator model uses the state-of-the-art voltage-behind-reactance model of the induction generator; in this first part of the paper, the fixed-speed wind generator model is presented. The overall solving environment for the nonlinear system of differential equations representing the power system is the so-called Poincare map method. A rather useful feature to reduce further the calculation times is the availability of an equivalent wind farm model based on multiple wakes. The Poincare acceleration yields a vastly improved numerical solution compared to existing models of fixed-speed wind parks. The application of equivalent wind farm models yields a staggering reduction in the elapsed time to only 1.16% of the time demanded by the detailed model, while retaining a good approximation of the response of the wind farm. Full comparisons of the detailed and equivalent wind park models with PSCAD/EMTDC, are carried out and the agreement of the results is excellent. In this paper the emphasis is on harmonic generation.

Sustainable siting of an offshore wind park a case in Chania, Crete

Large Wind Parks (WPs) are an essential priority, mainly in non-residential districts. Especially the offshore WPs, in areas with valuable energy potential, without legislation prohibits and without causing disturbance to the nearby community, could release enormous land for other uses (culture, recreation areas, tourism, etc.).The aim of this paper is to present a methodology for the sustainable siting of an offshore WP based on legal limitations, with a particular respect of ecological and economic resources using as example the island of Crete. It will also be considered the visual, acoustic and aesthetic disturbance of the coastal area residents and visitors and integrate them into the context.One of the essential issues that make the region unique is the undersea relief, which makes difficult the numerous and large-scale intervention, because some areas are strictly protected by the EU.Three steps have been followed: (i) exception of unsuitable areas (geological restrictions, visual and acoustical disturb and safety and of course due to environmental conditions); (ii) evaluation of environmental impacts on birdlife, Special Protection Areas and Sites of Community Importance; (iii) assessment of wind potential and needs of electricity in the regional unit of Chania, in the Western Crete.

A new methodology for urban wind resource assessment

In the latest years the wind energy sector experienced an exponential growth all over the world. What started as a deployment of onshore projects, soon moved to offshore and, more recently to the urban environment within the context of smart cities and renewable micro-generation. However, urban wind projects using micro turbines do not have enough profit margins to enable the setup of comprehensive and expensive measurement campaigns, a standard procedure for the deployment of large wind parks. To respond to the wind assessment needs of the future smart cities a new and simple methodology for urban wind resource assessment was developed. This methodology is based on the construction of a surface involving a built area in order to estimate the wind potential by treating it as very complex orography. This is a straightforward methodology that allows estimating the sustainable urban wind potential, being suitable to map the urban wind resource in large areas. The methodology was applied to a case study and the results enabled the wind potential assessment of a large urban area being consistent with experimental data obtained in the case study area, with maximum deviations of the order of 10% (mean wind speed) and 20% (power density).

Visual impact assessment method for wind parks: A case study in Crete

The number of large scale wind parks (WPs), has gradually increased over recent years as a result of the support by national and European policies. Even though it is a more environmentally friendly electricity generation option than conventional power stations, large WPs pose questions concerning their visual impact in the areas they are located. Particularly when there are no clearly defined siting criteria, land use conflicts are more intense, leading to the inhibition, and delaying, of wind park projects.In this paper, a methodology for the assessment of wind parks’ aesthetic integration, and for the support of public decision-making processes, was developed.The main asset of the proposed methodology is the combined use of quantitative indicators and dynamic 3D computer simulation. The visual impact of a WP installation is determined, through the comparative consideration of the quantitative and qualitative results. The proposed methodology simulates the changes after the WP installation realistically and calculates the grade of the visual impact, and was applied to a WP in the prefecture of Chania, Crete.

Modelling, Simulation and Analysis of Full Power Converter Wind Turbine with Permanent Synchronous Generator

This paper focuses on PSS/E modelling and simulation of wind farms of full scale converter wind turbine with permanent magnet synchronous generator and their impact on issues of Kosovo power system operation. The proper modelling of wind farm projects in systems studies is becoming increasingly important to system operators. In the past decade, wind power has evolved into a significant renewable energy source which continues to grow rapidly. The increased size of wind power projects and the development of large wind parks bring about a number of opportunities and challenges. Wind grid code currently require wind turbine to have high immunity against grid faults. In addition, wind turbines that are able to provide more reactive power support are increasingly preferred. This feature can be found in a full converter wind turbines with permanent synchronous generator.

Measuring a Utility-Scale Turbine Wake Using the TTUKa Mobile Research Radars

Abstract Observations of the wake generated by a single utility-scale turbine and collected by the Texas Tech University Ka-band mobile research radars on 27 October 2011 are introduced. Remotely sensed turbine wake observations using lidar technology have proven effective; however, the presented radar capabilities provide a larger observational footprint and greater along-beam resolution than current scanning lidar systems. Plan-position indicator and range–height indicator scanning techniques are utilized to produce various wake analyses. Preliminary analyses confirm radial velocity and wind speed deficits immediately downwind of the turbine hub to be on the order of 50%. This introduction lays the groundwork for more in-depth analyses of wake structure and evolution using the Texas Tech University Ka-band radar systems, including wake meandering and wake-to-wake interaction in large wind park deployments.

Mitigating subsynchronous resonance and damping power system oscillation in a series compensated wind park using a novel static synchronous series compensator control algorithm

ABSTRACTThis paper presents a novel damping control algorithm for static synchronous series compensator (SSSC) in a series compensated wind park for mitigating subsynchronous resonance (SSR) and for damping power system oscillations. The sample test system, adapted from the IEEE first benchmark model on SSR replacing the synchronous generator, is employed aggregating wind park based self‐excited induction generator. Consequently, it investigates the SSR phenomena and the damping power system oscillation while integrating large wind park based on SEIG. The potential occurrence and mitigation of the SSR caused by induction generator effects as well as torsional interactions, in a series compensated wind park, are investigated. The auxiliary subsynchronous damping control loops for the SSSC based on a novel design procedure of non‐linear optimization are developed. The performance of the controller is tested in steady state operation and in response to system contingencies, taking into account the impact of short circuit ratios (SCRs). The simulation results are presented to demonstrate the capability of the controllers for mitigating the SSR, damping the power system oscillation and enhancing the transient stability margin in response to different SCRs. Copyright © 2011 John Wiley & Sons, Ltd.

Meteorological Aspects of Wind Park Design

AbstractA simple consideration - based on an analytically solvable model of the momentum balance - is presented, which calculates the reduction in wind speed at hub height in an indefinitely large wind park as function of surface roughness, atmospheric thermal stability, and the mean distance between the wind turbines in this wind park. Weakest reduction occurs for a wind park erected on a rough land surface during unstable thermal stratification (minus 2%). Highest reduction occurs for an offshore wind park over a very smooth sea surface during stable thermal conditions (minus 45%). This model can be used to find the optimum distance between wind turbines in wind parks. Likewise this model calculates the wake length of entire wind parks as function of surface roughness and thermal stability. For offshore wind parks wake lengths between 10 and 30 km are found, for onshore parks this length is much less. This additional information can be used to find the optimum distance between adjacent wind parks.

Waterspouts over the North and Baltic Seas: Observations and climatology, prediction and reporting

On 25 August 2005, three waterspouts were observed close to the research platform FINO1, 45 km off the German North Sea coast and situated in a prospected large offshore wind park area. We analyse this case in relation to the synoptic setting of a waterspout day over the Baltic Sea and compare it to the waterspout climatology of the German Bight and the western and south-western parts of the Baltic Sea. The waterspout hazard to offshore wind parks is assessed as about 1 waterspout per year and per 10 000 km 2 . So, should current scenarios for future wind park development materialise, their large total area may experience a waterspout every other year. The prediction of such events is investigated in view of concepts recently proposed for Mediterranean and western North Sea waterspout forecasting. Reporting issues influencing the climatology encompass both a weekend low in reported events, as well as a bias toward ship routes and main SYNOP times in ship reports. The latter may be mitigated by more reports from yachtsmen.

An optimization approach for wind turbine commitment and dispatch in a wind park

This paper describes an operational optimization strategy to be adopted at the wind park control level, that enables defining the commitment of wind turbines and their active and reactive power outputs following requests from Wind Park Dispatch Centers, assuming that individual wind turbines short-term wind speed forecasts are known and are expressed as power availability. This operational strategy was also developed with a concern on the minimization of the connection/disconnection changes of the individual wind generators, for a given time horizon. When identifying the active/reactive dispatching policies, wind generators loading capabilities are also taken in account. This optimization tool is especially suited to manage large wind parks.

Transients in collection grids of large offshore wind parks

AbstractIn this paper, transients that can occur in collection grids of large offshore wind parks (WPs) are investigated. Issues concerning modeling of components, such as cables and circuit breakers, for transient studies are discussed. A WP including 80 wind turbines for a total rated power of 160MW is simulated with PSCAD/EMTDC (Manitoba HVDC Research Centre, Winnipeg, Manitoba, Canada). Examples of transient events occurring in the WP are presented. Both switching operations in normal conditions, such as energizing feeders, and faults are considered. Copyright © 2007 John Wiley & Sons, Ltd.