Skip to main content

New innovative solutions, components and tools for the integration of wind energy in urban and peri-urban areas

Final Report Summary - SWIP (New innovative solutions, components and tools for the integration of wind energy in urban and peri-urban areas)

Executive Summary:
SWIP aimed to overcome the barriers that the SWT has to achieve a wider deployment. In this sense, the normative and regulatory framework applicable to this technology has been assessed, analysing also the regional and local promotion of SWTs technologies by means of local energy plans in different locations. In general terms, there is a lack specific regulation. Definitively, SWTs need to be put on the agenda of policy makers.
A questionnaire has been elaborated and distributed over the SWIP website as well as in paper in order to assess the social acceptance of this technology. The result of this assessment brings that the rejection of SWT technologies is driven more by performance and costs. Once these issues are overcome, society appears ready to embrace the technology. However, at present, these technological issues are also inhibiting market acceptance, with consumers identifying other technologies as more interesting, and as being better investments.
Wind resource assessment at urban and peri-urban areas has been studied within the project with the aim to improve the location of the wind turbine and thus improving the revenue of wind turbines by means of more active working hours. The implementation of thermal gradient into two already software has allow to improve the existing software with this new feature.
In order to lower the cost of this technology, modularity has been applied over the design of Permanent Magnet Generators as well as the development of a post-assembly magnetization technique. The reduction of costs of magnets has been targeted through the development of a production method that allows to produce magnets with lower content in Rare-earth materials. Finally, converters have been developed tailored to the generators designed. A cost-competitive SCADA system has been designed and manufactured for monitoring and O&M works of the SWTs.
Guidelines have been created to take the knowledge learned from larger scale wind, and other renewables on one hand and from the detail experiences of installing SWT at the pilot scale on the other and to extract from these generalizable guidance that can be applied to the decisions involved in installing SWTs in urban and peri-urban areas.
New blades have been designed not only to achieve high performance but also to reduce the noise emitted. Sound propagation software in urban terrain has been developed using local terrain as well as a range of tools to perform source modelling for VAWT and HAWT designs.
Finally, part of the developments deployed in the project have been tested in two demo sites. In Choczewo (Poland) a 2kW Vertical Axis Wind Turbine has been tested while a 4kW Horizontal Axis Wind Turbine has been tested in Zaragoza (Spain).

Project Context and Objectives:
The Wind Energy Roadmap, which was published by the European Commission (EC) on October 7th, 2009, and was presented and discussed at the Strategic Energy Technology Plan (SET-Plan) workshop, plays a key role in fighting climate change and in helping EU Member States to meet the 2020 targets identified by the RES Directive of December 2008, which set the following goals for the wind energy sector:
• A wind energy penetration level of 20% in 2020;
• Onshore wind power fully competitive in 2020;
• 250.000 new skilled jobs created in the EU by the wind energy sector in the 2010 – 2020 period.
The major application of wind power is electricity generation from large grid-connected wind farms. However, following the changing trend of the energy sector from a centralized energy system to a distributed one, small wind systems and its hybrid applications are expected to play an increasingly important role in the forthcoming years, meaning a higher share in the energy generation. With the support of the smart grid technology and fostered by the directives and regulation associated to the sector, small wind turbines (SWTs) can now be connected to the electrical grid from the consumer end and, little by little, contribute to the stabilization of the electrical grid. Due to this fact, small-scale wind energy has now been applied in fields such as mobile communication base stations, offshore aquaculture, agricultural and farming and sea-water desalination, among others, in several countries. Besides this scenario, the integration of small wind energy in urban and peri-urban areas is being a challenge due to the barriers the technology has at this stage of development.
There is an increased awareness on the importance of the renewable energy sources to satisfy the energy and low carbon goals Europe is fostering, although the sector has to overcome these main barriers identified for the penetration of this technology in urban and peri-urban areas, where the exploitation potential and benefits for society are seen as the most promising ones. Following, a first overview of the reasons behind each barrier is given.
1. Cost of technology
The future of the small and medium size wind industry depends mainly on the cost of the technology, the evolution of the fossil fuel prices and investor interest. The energy experts anticipate high growth rates for the production of SWTs if the awareness rises and then the consumer demand increases. Nevertheless, cost remains to be the most influential factor for the deployment of SWTs.
2. Wind resource assessment
Wind evaluation currently presents challenges for the small wind industry due to the expensive wind measurement tools in urban environments. The shading and turbulence effect of surrounding obstacles produces inconsistent and unpredictable wind patterns below 30 m. As a result, the vast demand for inexpensive and efficient methods of predicting and collecting local wind data is another key driving factor that requires further innovation and cost reduction in the technology.
3. Regulation
The SWT sector is at the mercy of the regulation, as it is completely dependent of it. In this sense there is a light hint at the front, as European directives and the transpositions in the EU Member States are opening the path for the implementation of these systems in urban and peri-urban areas, opening the door to auto-consumption in households and other applications, such as the integration in districts. The steps that Europe is making in favour of this energy concept mean a definitive opportunity for the SWTs.
4. Social acceptance and safety
Several studies suggest that over 80% of the population is favourable to big wind farms providing clean energy to the electrical grid. Although the scenario is established this way for big wind energy generation installations, there is a lack of experience in the massive deployment of small wind turbines at urban and peri-urban areas. Nevertheless, everybody agree that it is necessary to have social acceptance for the successful development of wind projects. Although social perception is, a priori, in favour of these kinds of systems, there is a need to ensure this at urban level, as well as guaranteeing the health and safety issues around the technology and quality of life. These two topics should be at the core of the future developments, as are the points that may jeopardize the public awareness, and therefore the success of the technology.
5. Aesthetic, noise and vibration
Noise emission is one of the major concerns in wind turbine industry, especially SWTs one, which are mostly erected into the urban areas. Tonal noise emitted from the wind turbine installations, such as gearboxes or electrical power transmission parts, poses a serious environmental problem to the surrounding community, which is still a crucial point concerning the acceptance of WTs..
Vibration is another factor to address within SWTs, due to the impact they may have depending on the location where the device is installed. The primary vibration excitation mechanism is resonance of the dominant whirling mode of the turbine, with the operating blade pass frequency. In addition, resonance of the airfoil support struts at higher frequencies too. Vibration transmitted to the anchorage of the WT might be dangerous depending on the supporting infrastructure. Finally, aesthetic issues are key enablers for the social acceptance of these systems..
6. Wind market / user friendliness
The wind energy market has benefited from the traditional global trend of feed-in tariff (FITs). This scheme has fostered the technology development and integration of high energy generation rates in the system, being the main beneficiaries the wind farms that have been erected throughout Europe and worldwide. The FITs scheme in the small wind turbines sector has been absent and it is not envisaged in many countries, being the challenge to achieve competitiveness with current energy prices without external incentives. This barrier is closely related with the cost of technology, being the main aim of the SWIP project to achieve a product that is cost competitive in the market.
Moreover, proximity of society to information and communication technologies, mainly given by the wide use of smartphones, tablets and web support, needs to be exploited and taken as an advantage for the integration of new systems into society and their day-to-day life. Small and medium size wind turbines market must take advantage of this situation in order to bring nearer the consumer, the benefits the renewable energy sources have as well as enabling an easier understanding and use of the systems.
The main objective of the SWIP project is to develop and validate innovative solutions for small and medium size wind turbines to improve their competitiveness, enabling and facilitating the integration and deployment into urban and peri-urban areas.
The new and innovative solutions will address the current barriers (turbulence, noise, vibration, aesthetic aspect, cost of technology, wind resource assessment, wind market, user friendliness, social acceptance and safety) that delay the market uptake of this technology.
The project will develop two different prototypes to be integrated in two different scenarios (new energy efficient building and shore-line), to validate the solutions and goals aimed, providing scalable solutions for different applications, covering several user needs.
Moreover, the project will improve the current methodologies for wind resource assessment into urban and peri-urban areas, reducing the RMS error in wind speed estimation until 8%, minimizing the risk and the opportunity costs of the small and medium size wind turbines when they are integrated in these environments.
The specific objectives of the project are:
A. To set up a comprehensive benchmark that includes the most significant European legal and technical frameworks regarding small wind energy turbines regulations, the generation technologies and the energy plans for cities.
B. To develop a methodology for wind resource assessment in urban and peri-urban areas, able to predict wind speed in urban location with a maximum 8% standard RMS error, without the need of performing a measuring campaign, and to implement such methodology in a software. By means of that software the consortium will be able to assess and validate the accuracy of the model in the three locations in the project.
C. To design an innovative and low cost wind generator (between 1 and 100 kW) which could be adapted to different types of wind turbines deployments depending on its final emplacement. Two configurations of permanent magnet generator will be developed, one for direct drive connection and a second one for a gearbox connection.
D. To design and develop cutting-edge technology wind blades, which maximize the wind energy conversion in each type of final model, addressing small and medium size wind turbines and considering both vertical and horizontal axis for different use. The new blades will also contribute to the objectives of reducing vibration and noise coming from those elements, addressing the overall operation goals established in SWIP.
E. To implement a Supervisory Control And Data Acquisition (SCADA) system that will allow a better performance of the wind generator, through improved operation and maintenance. This system will be used for the control of the turbine, safety issues, operation mode selection and reliability improvement through preventive maintenance. Converters will be able to work both in isolated grid and connected to the network. Furthermore, their control will satisfy “The Network Code on Requirements for Generators” which will be certified once they are installed in their final locations.
F. To analyse the structure and anchorage elements of small and medium size wind turbines for their installation into districts and buildings and to develop best practices guidelines, for the aesthetic integration of these systems into urban and peri-urban settings so as to guarantee social acceptance of wind turbines, maximise civic (urban design) amenity and create positive visibility of appropriate urban wind devices. To increase market uptake and CO2 savings.
G. To develop and implement solutions to mitigate and to absorb the noise and vibration produced by the wind turbine and to study the existing regulations regarding the safety issues in small wind turbine operation
H. To define and execute a complete testing of the technologies, solutions and new components for small and medium size wind turbines developed within SWIP in three different pilots across Europe and to validate the final behaviour and energy performance and compare it to the goals aimed.
I. To deal with the dissemination issues (aiming at disseminating the project results and achieving the highest possible project impact and visibility) and the exploitation ones (aiming at paving the way for further industrialisation and commercialisation of the SWIP results).
J. To develop an effective and comprehensive SWIP administrative and financial management to ensure the successful execution of SWIP

Project Results:
The SWIP project aims to overcome the main barriers that the SWT sector has. In this line, several results have been obtained within the project which will certainly contribute to get this technology closer to the market. The project has targeted those barriers and finally a demonstration with part of those results has been deployed.
The SWIP project devised a questionnaire to explore socio-political acceptance, market acceptance and expected community acceptance. The questionnaire explored expected reaction to SWTs, familiarity, investment barriers, interest in competing solutions, and ownership options, as well as collecting background information such as demographic data and attitudes to renewable energies and wind turbines in general. The responses have been analysed in this report and are summarised under three research questions.
1. What is the current awareness level and public opinion of SWTs?
The questionnaire found that just over half of respondents had previously seen a SWT in an urban environment, and that three quarters of respondents believed they would have a positive response to a SWT in their living environment. Comparing expected reaction to SWTs and large turbines shows that across all demographics, SWTs were expected to be more acceptable than large turbines – including in rural areas. Industrial sites were regarded as the most acceptable installation sites for SWTs, far ahead of the second place option of installations on roofs in residential areas.
2. What influences current opinions of SWTs?
There appeared to be no actual correlation between having previously seen a SWT and expected reaction to one. Although there was some correlation between reaction to SWTs and large turbines, the picture is nuanced – not all those who would accept one technology would accept the other. Younger people were more positive than older demographics to SWTs and were more likely to express an interest in owning one. Urban populations had a more positive reaction than rural ones, and higher educational backgrounds also responded more positively.
3. What are the key barriers to the uptake of SWTs and what can overcome them?
The main barriers to investment are technological and economical (market acceptance), rather than social, with respondents being concerned about performance of SWTs, as well as high investment costs. Respondents indicated that they were least concerned with visual impact, flicker and safety issues. The results also show that individuals were considerably more interested in competing solutions, especially Solar PV, and that SWTs were the least interesting of the decentralised energy solutions. Technological improvements and cost reductions were identified as being essential for improving uptake. Respondents were largely unconcerned about visual impacts, suggesting that the visual presence of SWTs could be highlighted as a unique selling point for the technology, compared to PV. Co-ownership options were widely appreciated, and interest in co-ownership of a turbine was high – with even 45% of those saying they had no interest in SWTs saying they could be interested.
Within the SWIP project energy plans in for EU cities have been described and three relevant European cities have been analysed in order to determine the possibilities and space the SWTs have within the future concept of those cities.
At the moment, there are hardly any examples of city energy plans taking into account the possibility of installing SWT’s. Some EU cities mention SWTs in their municipality regulations, and also several local SWT’s-projects are being carried out around Europe.
It is of increasingly importance for city energy plans to take into account SWT solutions in urban planning. The productivity of SWTs heavenly depend on the ‘micro conditions’ around the turbine (e.g. wind conditions at a given location, architectural and structural conditions of the building and environment), which only can be used in an optimal way when these are taken into account in the city energy plans (a city plan is able to focus on these ‘micro conditions’). Also the interaction with other developing energy technologies plays a large role in exploiting the potential of distributed SWT’s. The amount of applications for SWT’s increases due to this developing technology, where SWT’s can be used in a combination with e.g. electric bicycles, city buses, street lighting, electric vehicles, etc. Also a synergy for combined systems of PV and SWT offers partial solutions to intermittency problems of Renewable energy
sources. To benefit from these synergies city energy plans need to take into account these possibilities and chances for SWT’s.
After analysing the responses from the questionnaire developed by the SWIP project, some recommendations for Policy-Makers and Businesses have been developed:
• Recommendations for Policy-Makers
Policy makers need to consider SWTs differently to other more advanced renewable technologies, as acceptance of renewable energies, and of wind energy cannot be assumed to transfer across technologies to SWTs. To this end, dedicated support tools and communications campaigns are essential if the use of SWTs is to increase. A starting point here would be communications campaigns that tackle performance and cost concerns by focusing on wind resource availability and making recommendations on technologies and installers. Choosing the correct installation site for a SWT is essential for good performance, and whilst this is a complicated process, authorities can release district level wind mappings which may be quite basic, but can at least indicate where turbines should abSOLUTEly not be installed, and where they could be considered.
Urban planners should question the use and placement of SWTs if there is not clear evidence provided that the turbine will actually function; anything else is bad advertising and wasted investment. Given higher acceptance levels, SWTs and medium turbines may be suitable for regions where large turbines have been rejected in the past. Installations for multi-tenancy housing could also be an option, especially if mixed with a co-ownership option. However, clear communication is needed to avoid community rejection.
• Recommendations for Businesses
The SWIP survey reveals that there is a market for SWTs, if current barriers can be overcome. Businesses should stress the competitive advantage of SWTs over competing solutions – high visibility and novelty – but avoid greenwashing; performance concerns will not disappear until businesses are really able to deliver what they promise. To this end, industry will need to focus on correct installation and maintenance, if SWT businesses are not to suffer in the long-term. Advertising should focus on turbine design-visual impact, yield, and expected return-on-investment, but manufactures should be realistic, and installation should be advised against unless there are sufficient wind resources.
For increasing market penetration, co-ownership opportunities should be explored, particularly for the two main identified markets of younger demographics in urban areas, and industries in peri-urban and industrial sites. Young people in urban environments were more accepting of the technology, but also have greater affinity with co-ownership and sharing economy concepts. In peri-urban and industrial areas, there was higher acceptance of installation, and being away from residential areas, mid-sized turbines could be used for multiple ownership.
New business models, such as service based contracts, where individual firms are responsible for siting, installing and maintaining SWTs could help to overcome concerns about cost and performance. If a business can deliver a turbine, site it correctly, install it correctly, and monitor performance, and recuperate costs either through leasing, or through a generation based payment scheme, where users pay based on performance criteria, then it could dramatically alter the way that people think about SWTs.
• Recommendations for consumers
Consumers should question the performance of the turbines, and be wary of the promises of manufacturers and installers, before installation. Get a wind resource assessment, or at least check a wind map, before paying anything.
To think about neighbours and the impact that an installation may have on them – they will not benefit from installation, but will need to be involved and consulted. Deliver mock-ups on how it would look, and tackle any concerns head on regarding noise or safety concerns.
One of the main barriers that the Small wind turbine technology has that the resource assessment is not accurate enough to allow to select the proper location to install a wind turbine in urban or peri-urban environments. These environments are characterized by wind with high turbulence and usually are not directional. A correct wind resource assessment allows to better locate the wind turbine in these environments and then to be able to obtain higher power productions.
Two wind resource software have been upgraded thanks to SWIP project: METEODYN WT which deals with large scale CFD problem in turbulent atmospheric boundary layer, and UrbaWind dedicated to CFD modelling for wind estimation in urban areas. These software improves the wind resource assessment in urban and peri-urban environments from the state of the art.
The new release, taking advances of the SWIP results, is named V5.3. Previously, the boundary layer had some characteristics depending on thermal stability conditions. The whole thickness of the computational domain was modelled based on MOST (Yamada and Arrit model).
Nevertheless, the scale was quite short. For highly stable atmosphere, this model is true only close to the ground. In order to enlarge the scale, 2 stability classes are introduced for very stable cases. The first stability classes are unchanged (upward compatibility), while a quite intensive work was done for the two news classes, as the boundary layer was stratified in three layers: MOST (close to the ground, same a small stability classes), Local MOST, and outer. This modification was quite deep since it has to modify the solver itself.
This modification has a huge impact in the synthesis part (post-processing): now, because the scale is large enough, it is possible to use a different stability class for each time step. In other words, it is possible to reconstruct a complete history (time series) taking into account the thermal stability, not only some statistics. Thus, a new functionality of WT appeared with the “TIM-TIM synthesis”.
• UrbaWind
The release which uses the results of SWIP project is named V2.2.1. Close to the ground, within a city, the thermal stability is always neutral because of high level of geometric constrains. This enhances the mechanical part in the energetic exchanges and thus, reduces the thermal effects.
Nevertheless, above the mean height of the buildings, which is called the urban canopy layer, the exchanges are again linked with thermal stability. In UrbaWind option “stability effect”, the user is allowed to modify the thermal stability above the canopy through the tuning of Moning Obukov length. This affects the in-canopy flow pattern throughout the “forcing” term at the interface between canopy and first layer. Example is shown in the next figure, with the same simulation with three different Monin Obukov lengths

The cost of the technology remains to be the most influential factor for the deployment of SWTs. SWIP project has been focused on the reduction of those costs targeting different aspects of the generators such as:
• PMG y PMSG software

A new performance evaluation methodology for permanent magnet synchronous generators to be used when designing optimal generators for small wind power applications in urban and peri-urban environments was developed within the SWIP project. The design method developed was applied to design generators of 2, 4 and 20 kW, using real component characteristics and wind resource data.
The implemented methodology consist of obtaining the widest range of suitable generator designs according to the application needs, and further evaluating the performance of each design for variable wind speed conditions when coupled to other influential wind turbine components. All plausible designs are obtained and evaluated, and the most relevant data involved on the generator selection are output for every design, helping the designer to select the most suitable permanent magnet generator design. The main selection criteria for the generator are economic, based on optimizing raw material cost while increasing production, leading to a maximum profit on the selected design. Additional aspects, for instance dimensions and weight, have an appreciable impact on the wind turbine selection and have also been considered as well when choosing the best generator design.
A software application has been developed to optimize the design process. The tool allows to obtain a wide range of high efficiency generator designs on the small wind turbine power range (up to 100 kW), according to user defined design inputs. Several software features regarding calculation speed, usage of either tailored or commercial laminations during the design, calculation stages to increase result accuracy, and operation boundary consideration have been implemented to achieve the design objectives. On the other hand, the generator technical inputs have been related with other component characteristics (blades, converter and control), establishing relationships between them in order to guarantee optimal generator compatibility through proper generator design input selection.
For the best designs and for selecting the optimal generators, production and profit are calculated from the power curve and the wind distribution typically found on peri-urban and urban locations. Length and load angle are also considered in the selection process. After the optimal generators are selected, their electromagnetic, electrostatic and mechanical behaviour are analysed using finite element software. Regarding operation capabilities, cogging toque, magnetic saturation, and induced voltage harmonic content have been obtained through electromagnetic simulations. From these analyses, it is concluded that for every generator design, cogging torque amplitude is far under the starting torque provided by the blades, allowing the start-up of small wind turbines in very low wind speeds. Furthermore, saturation problems have been detected in specific points of the stator lamination (teeth tip), but they do not affect to the generator performance.
The use of the software allow to design the best Permanente magnet generator in time effective process while the use of the Permanent Magnet generators for SWTs allow a cost reduction by means of the use of less raw materials to manufacture the generators.
• Post assembly magnetization technique
Concerning the magnetization process, since both electric and magnetic circuits influence each other, they shall be designed/selected together to ensure magnetization success, and thus can be considered that magnetization is a dual process, both electric and magnetic, in which both parts are coupled. In order to properly design or select both circuits, it is necessary to know how the design
variables in one circuit impacts the performance of the other. In this sense, the most optimal design for one circuit may jeopardize the performance of the other circuit, making the overall performance far from optimal. A sensibility analysis has been performed to give the user information on how the magnetization is affected by a change on the design variables, allowing to select them properly and optimizing the magnetizing performance.
With the aim to apply this novel assembly technique with good results a set of requirements must be fulfilled, regarding the energy source used to perform the magnetization, generator to be magnetized sizing, and the strength and homogeneity of the magnetic field generated. If any of these three conditions fails, it will cause that the results are not desired, either inadequate or unbalanced magnetic characteristic in magnets, or because the generator cannot handle the stress of magnetization process.
The results obtained for the post-assembly method improve the results of the conventional method in all scenarios evaluated, which has covered a variety of pole numbers and magnets simultaneously magnetized. Depending on the characteristics of the rotor to magnetize, production is improved between factor 1.80 and 5.78 while the assembly cost per rotor may drop between 16.8% and 79.9%.
In addition, the technical studies performed have allowed to confirm that a 1.7 kW – 165 rpm synchronous generator with NdFeB magnets can be successfully magnetized by means of a partial post-assembly method, using the criteria previously defined. For the studied geometry (105 mm length magnets) can be concluded that there is an optimal pole number that minimizes the number of shots required to magnetize the rotor, that will be at the same time the most favourable reducing the assembly times and costs. For this case under study, magnetic fields above 3.2 T are obtained for 20 and 16 pole rotor designs, being necessary to perform 4 cycles to magnetize all poles in both cases, demonstrating the technical feasibility of the method for the studied geometry.
Furthermore, when the results from this technical analysis are crossed with the results obtained on an economic analysis, it can be concluded that the 20 poles / 4 magnetization cycles required design increases productivity by a factor 4.10 and reduces costs by 68.7%. It is thus demonstrated that the post assembly methodology is both technically viable, safer, enhances production and more economically profitable than the conventional manual assembly technique.
• Rare earth materials on permanent magnets
The DARMS managed to develop a production method, based on the Grain Boundary Diffusion Process (GBDP), which allows manufacturers to produce permanent magnets for high temperature application with reduced HRE content.
Optimized production of Nd-Fe-B magnets requires instruments that pay off with extreme production scales and usually process alloys with additives. In this work a suitable process is for the first time established on site to produce sintered Nd-Fe-B model magnets tuneable in composition, grain size, phase shares and density. Aim was to study potential influences of these well-defined microstructural parameters on the diffusivity of HRE and eventually raise the treatable length scales by GBDP.
By GBDP, DARMS has produced Nd-Fe-B magnets with only 1.5 to 2 wt. % of Dysprosium. This a reduction of 75 %, compared to the commercially available permanent magnets, which typically contain 6-8 wt. % of Dysprosium. Moreover the Neodymium is substituted by Cerium.
In order to optimize the power output of the generators, and thus obtain higher efficiencies, specific converters have been designed and manufactured to obtain the maximum power out possible from the generators.
With the aim to adapt the variable conditions of the permanent magnet synchronous generator (PMSG) to the stable conditions of the grid, a full converter is set between the low-voltage grid and the PMSG. This full converter is composed of two power converters, able to manage and adapt the power from the PMSG to the grid. These two converters are called VSC Controlled Rectifier and VSC Controlled Inverter.
• VSC Controlled Rectifier
The rectifier is an element which is in charge of taking the maximum power from the wind turbine in each moment by means of an optimum power tracking algorithm (MPPT for wind turbine). To achieve this goal, the control system is divided in two main control loops:
✓ The first control loop deals with the speed of the machine. This speed control loop stablishes the reference of active power on each instant. Taking more or less active power from the generator, the control system is able to act over the rotating speed of the machine, accelerating or decelerating it. If in one moment it is necessary to decelerate the system, the control will require more active power from the generator, while the control will accelerate the machine if it demands less active power than in a previous moment.

✓ The second control loop acts over the voltage at the terminals of the Permanent Magnet Synchronous Generator (PMSG). This control is able to manage the voltage of the machine through the control of the reactive power flow exchanged between the generator and the power converter. With this strategy is possible to maintain the optimum working point of the generator, reaching the maximum efficiency.
Depending on the wind resource in each moment, and taking into account the maximum power point tracking algorithm, the generator-side control system stablishes the current taken from the electrical machine (both active and reactive), the speed of the machine and the voltage at its terminals. The control strategy to be developed will fix the performance conditions of the wind generator on each instant.
• VSC Controlled Inverter
The other power electronic converter acts as a power inverter, taking power from the DC bus to the AC grid. This inverter is in charge of controlling the connection of that DC bus (and so the wind turbine) to the grid. It synchronizes the performance of the wind turbine with the external low voltage grid. For this goal, two types of control loops are also implemented in the system:
✓ The first one is able to keep the value of the DC voltage constant. Keeping constant the DC voltage value, it ensures that the active power flows from the PMSG to the grid through the power inverter. So, the inverter extracts, from the
✓ DC bus to the external grid, the optimum active power that the VSC Controlled Rectifier has taken from the PMSG.

✓ The second control loop acts over the reactive power exchanged between the power inverter and the grid. In the steady state, it is possible to work with reactive power equal to zero, i.e. power factor equal to one or even it may be able to participate in node voltage regulation providing or absorbing reactive power. Moreover, in transient state through these control loops, it is also possible to accomplish with different grid codes, dealing with the active and reactive current injected to the grid during disturbances as voltage sags.
The control theory applied for controlling both converters is the dq-vector control. These algorithms were developed, simulated and implemented into a microcontroller. A total efficiency of 95% was achieved in the converters and also some innovation was applied such as the regenerative brake normally used for train and electric vehicle applications.
In addition to the coupled system generator-converters optimized, how to improve the behaviour of the wind turbine by means of a better maintenance also contribute to a cheaper product. In this sense two SCADA systems have been designed and assembled, one of them intends for H4 small wind turbine and the other one intends for H20 wind turbine. Both are composed of two devices: the SCADA core, which contains the main services (database, web server...) and the data acquisition module, which gathers the meteorological mast variables. Additionally, the H20 SCADA has a communication module to implement the wireless connection at the wind turbine converter.
The H20 SCADA system supports wireless communications since the pilot site does not allow wiring the three devices. A wireless system was implemented based on radio modules. As signal may travel through several walls (indoor environment), all radio modules repeat master frames in order to reduce the packet error ratio.
Several software modules have been coded to perform the SCADA functions: acquisition, communications, recording and interface.
A web-based interface has been developed to interact with the SCADA system. Users can check the SCADA measurements and set several configuration values. Currently, online and historical data from the meteorological mast can be represented. Screens regarding the electrical data are unavailable for now. Two screenshots show the final SCADA appearance.
The main objective of the SCADA system beyond providing a useful set of characteristics was to be a cost-effective SCADA system, by means of the SCADA system developed a target costs of 300€ has been met.

The potential problem of noise from small and medium sized wind turbines in urban and peri-urban environments has been evaluated and assessed. In order to assess the noise problem a broad approach evaluating both how sound is generated, propagating and finally evaluated by humans has been necessary as all these parts constitute important steps to understand if and how an expansion of wind power will affect the urban living environment.
From the work on aeroacoustic source models there are evident that different approaches are required for the vertical axis and the horizontal axis turbines. The trailing edge-turbulent boundary layer noise seems to dominate for the vertical axis turbine while the inflow noise seems to dominate the horizontal axis turbines.
Sound propagation should also been separated, in this case between urban and peri-urban terrain. In peri-urban areas refraction and diffraction effects are dominating the propagation and for urban areas the reflection effects seem to be of pivotal importance. Models to capture these different phenomena have been developed and showed plausible results.
Acoustic measurements have been performed at several small and medium sized turbines during the project, these aims at collecting recordings for listening tests. Binaural recording techniques have been chosen in this measurement campaign because this provides input of higher quality to listening tests. To improve the recording technique and decrease the amount of disturbances a novel wind shield of the ears have been developed and examined. Further, listening tests have been conducted using a continuous judgement technique. These tests have been used to investigate how to best perform masking tests as the urban soundscape is different from the usual rural landscape where wind turbine noise is usually present.
How noise is perceived is indeed a complicated matter. Recordings of large turbines are preferably performed in night time when ambient noise (such as birdsong and traffic noise) are quiet and the wind conditions at hub height are high while the wind speed at ground height are low. However, for small and medium sized turbines the wind speed at ground level needs to be high in order for the wind turbine to rotate and therefore improvements of the recording techniques are necessary to avoid pseudo noise. The assessment of ecologically relevant sound stimuli are facilitated by the verification of the headband mounted wind shield. The loudness assessment tests show that short term amplitude variations (amplitude modulations) increase the detectability of wind turbine noise. The tests also shown that there are potential large inter-individual differences in continuous loudness perception. Masking will be an important effect to consider in urban wind turbine site evaluations, and good models for assessment are therefore important.
Blades are the element of the wind turbines that is responsible of the majority of the sound generated. How the blades of small wind turbines exist and appear in the built context depends on the receiving environment, the geometry, materiality, form, frequency and relationship to the host building, of the blades. Potential improvements to current practice in selecting, locating, and specifying SWTs are possible and have been identified by studies undertaken in this work and by drawing methodologies in from parallel disciplines. A set of selection Guidelines (considerations and questions) for wind turbine and blade development such that they can more successfully be integrated into buildings, urban districts and other suitable areas is set out.
Some guidelines have been created to address both analysis protocols, decision making procedures and turbine/blade functionalities. Also considered are wind turbine/ blade type, building, location (at medium and micro scale) and design integration potentials. The work herein summarized has emerged from and informed the design (and later manufacture) of the SWIP projects SWT prototypes.
The blade designs for the two horizontal and one vertical wind turbines were carried out, this designs were done not
only to have an optimized power output but also to minimize the noise generation. Feedbacks were given on the wind turbine designs from the CFD analysis through different steps in order to address the objectives of the task comprehensively.
Fluid flows around the blades of the two horizontal wind turbines were simulated and carefully analysed in three-dimensions in order to evaluate the wind flow structures around the blades, especially at the tip of the blades where new design concepts were implemented. Furthermore, the aerodynamic performances of the wind turbines were assessed at three representative wind conditions, i.e. the design, the most frequent and the average wind speeds of the demonstration sites for each respective turbine.
Fluid flow across the vertical axis wind turbine was simulated in order to investigate the extremely complex and dynamic behaviours of the fluid flow around the blades and along the flying path of the blades. Both the design condition and the off-design conditions at different tip speed ratios were investigated. Power generations from the turbine were also estimated for the design, the most frequent and the average wind speeds of the proposed demonstrate site.
The results of the CFD simulations for the horizontal turbines in terms of the structures of the flow around the blade indicated that both turbines can operate well at the designed operating conditions. Moreover the results from the loading and power performance calculations of the turbines were in good agreement with the design values although slightly less than what were calculated at the design stage. In addition to the power production, the pitch torque and the thrust force were estimated to contribute to the design of an appropriate pitching system and the structure strength of the blade at the hub, respectively.
In the case of the vertical axis wind turbine, the details of the unsteady flow at different azimuthal angles around the rotating axis were analysed and the effect of the flow separation and vortex generation on the pressure distribution/load and the performance of the turbine was studied. The power coefficient at various tip speed ratios and at different wind speeds have been estimated.
Since all three turbines were designed to operate in urban and pre-urban areas where the wind flow can be contaminated, sensitivity of the wind turbine performance to the blade contaminations was studied. It was concluded that in the worst scenario the roughness built up on the leading edge of the turbine blades can diminish the lift coefficient of the blades by up to approximately 9-15% and consequently lead to a considerable loss in the power output. It is strongly recommended that regular cleaning of the turbine blades should be arranged in the case where severe contaminations exist. Alternatively it would be desirable to use smooth coating over the turbine blades to avoid building up of roughness due to contaminations.

During the course of the project, results obtained in different areas needed to be connected in order to provide an integrated set of solutions. A set of guidelines have been produced to help the integration of wind turbines into buildings and districts, and going beyond, to be a consultation document for those individuals or organizations that aim to install a small wind turbine.
These guidelines have taken the knowledge learned from larger scale wind, and other renewables (large and small) on one hand and from the detail experiences of installing SWT at the pilot scale (the SWIP demonstration projects) on the other and to extract from these generalizable guidance that can be applied to the decisions involved in installing small wind turbines (SWTs) in urban and peri-urban areas.
Whether the reader is the SWT owner, installer, regulator or even neighbour potentially affected by a SWT installation, complex questions - from matters of principle to matters of detail- arise. The installation of SWTs may be carried out in pursuit of a number of objectives from making environmental progress visible, to mitigating climate change and from earning money to ensuring the stability of ones power supply or simply wanting to comply with building energy regulations. These are all valid reasons to install SWTs.
At the next level general scale questions arise, these may include: What benefits do SWTS bring and how much energy can be generated and money earned (or saved) from them? What regulations and procedures influence the process and what is the ideal site, location or even type of turbine to install?
WTs at small scale and in urban location can be productive if installed in ideal circumstances, however the corollary is that anything less than ideal conditions can reduce the benefits rapidly. The chance of success can be improved by reducing the financial risk (with grants or feed in tariffs on energy generated), by thorough preparation (site assessment, becoming familiar with regulatory requirements, and consulting the local community) and by getting professional advise (on site energy availability, turbine selection, approach to installation or integration, how to connect) and by managing and maintain the WTs themselves.
Once these high level answers have been arrived at, a process of more detailed comparison and specification must be undertaken: A site or host building must be selected that is higher than its surrounding and not sheltered from the downwind direction. It must be assessed for the general and specific wind energy availability using on site measurement and MCP computer modelling methods and the type and location of turbine derived from these findings. Horizontal axis turbines suit sites with more constant winds but may suffer vibration, noise, and shadow flicker, while vertical axis turbines can take wind from any direction and are generally more stable. Crossflow, turbines can also be used. The size of the turbine must be derived from considering the energy (demand) profile of the building compared to the potential energy available at the WT location and factoring in issues of regulation, as well as whether a grid connection, net metering (or feed in tariffs) are available and whether sizing for the buildings base load or to produce a (sellable) surplus would be most beneficial or not.
Urban and per-urban turbines can be installed independently near the building, stabilised by and adjacent to it, or structurally integrated onto it, though this requires a thorough examination of the buildings structural design, spare capacity to absorb additional loads and what ways to mitigate vibration and ensure weathertightness after integration might exist. Structural connections should include damping to reduce risk of vibration. Maintenance of the turbine and tensile elements of the support can reduce noise and nuisance. Further aesthetic enhancements including colour and architectural integration are also possible and can improve social acceptance.
Durability and maintenance are important aspects of SWT installation and are interrelated with structural integration as well as overlapping with the important considerations of value for money and return on investment. These financial considerations are as important as they are complex being affect by capital cost (and supports if any), sizing, energy output and lifespan, availability of grid connection, feed in tariff and maintenance cost.
As part of the project, SWIP partners have designed, manufactured and built two Small wind turbines of 2kW and 4kW, which have been installed and tested in Choczewo (Poland) and Zaragoza (Spain), respectively.
2kW WT installed in Choczewo
Within the project a deployment plan was developed in order to have a smooth and successful installation of the wind turbine. After the mechanical design was done and the location of the wind turbine within the demo building was chosen, the wind turbine was assembly in Lithuania and shipped to Choczewo (Poland) to its installation. The wind turbine was installed and commissioned within the demo site.
4kW WT installed in Zaragoza
Within the project a deployment plan was developed in order to have a smooth and successful installation of the wind turbine. After the mechanical design was done and the location of the wind turbine within the demo building was chosen, the wind turbine was assembly in Lithuania and shipped to Zaragoza (Spain) to its installation. The wind turbine was installed, commissioned and tested within the demo site.
Lessons learned
During the manufacturing, assembly and installation of the wind turbines, the SWIP project had to face some difficulties from which some lessons have been learnt and can be of use for future developments on this sector.
• Testing of a prototype in a non-controlled environment
The fact that the prototypes were tested in a con-controlled environment caused that:
1. The safety factors considered for the mechanical designs (supportive structures, masts, blades, nacelle, pitch system, etc) were higher than the ones considered for a commercial wind turbines. The risk that any of the components could be broken leading to an undesired risk for pedestrians obliged the consortium to take this decision. Considering this, it does affect to the amount of material that these parts have, increasing its weight considerably which it is indeed a barrier for the integration of this prototypes into existing buildings, whose structure is not prepared for these kind of integrations.
2. Safety of people working in the buildings and pedestrians goes first, in that sense, part of the surrounding area of the CIRCE´s building needed to be fenced in (see picture below). Also, the first weeks after the installation, the rooms closer to the wind turbine of CIRCE´s building were evacuated and its workers relocated to different rooms.
3. Regarding the generators, safety factors has been also oversized. Due to this reason the dimensions and the weight of the generators have been affected, this oversizing was done to secure the correct working and the non-failure of the machines that could lead to safety failures. In order to get a more competitive generators, these safety factors should be optimized, that way, the material used and the dimensions would be lower and the generators would be more competitive.
In order to easy the testing of prototypes a controlled environment is desired prior to install the prototypes in a non-controlled environment. A controlled environment can also easy the operation and maintenance of the prototypes.
• Manufacturing of a first and single prototype
Within the project two prototypes wind turbines and four prototype generators (one of those was to test DARMS magnets) of a different power were manufactured, which means that each and every generator is different. When manufacturing a prototype from the scratch, a lot of factors and characteristics must be considered and analyzed during the design and the manufacturing, being an R&D activity, the chances that something could differ from the design are of importance. Once a prototype is already manufactured, even if there is some errors that could lower its performance or behavior, there is not much to do but to go forward.
From the perspective of getting better prototypes that also could achieve higher TRL within the project, it is considered that a different formula for the development of the prototypes could have led to a probably better results. A second prototypes of each generator (it also would have required more budget) would have definitively improved the final results of the project.
• Ancillary equipment
The use of ancillary equipment was assessed during the design phase of the H4 wind turbine, to be specific the installation of a slip-ring. By the installation of a slip ring in the H4 SWT, the wires torsion is avoided and the maintenance is reduced.
A slip-ring which fulfil the technical requirements of the H4 SWT was assessed. After a market research, the use of the slip-ring was discarded despite of the advantages that this equipment would five to the wind turbine. This choice was done based on equipment costs which were too high to be implemented in a wind turbine which aiming to reduce its costs per unit.
Slip-ring is an element that if it could be cost competitive would certainly improve the maintenance of the wind turbine and then the operating costs of the technology.
• Administrative paperwork needed for the installation
The administrative paperwork needed to install a wind turbine is considerable due to the need to get permits from all organisms and companies that somehow are going to be involved, such as city hall, distributed system operator, local government, etc..
In addition to this, special legislation needed to be fulfilled due to what it was going to be installed wasn´t commercial wind turbines but prototype wind turbines.
Due to these barriers, the times needed to get the corresponding permits got long in time and it also needed more resources, both in time and economic.
In order to allow a more attractive and secure framework for installing small wind turbines in urban and peri-urban areas, clear pathways for the installation of this kind of wind turbines is needed, which can only be achieved through general regulations, avoiding each local government or city hall to establish different restrictions or additional administrative paperwork.
• Normative framework
The novelty of the project makes that the normative framework is not well defined. In this way, there is not a clear normative that indicates which are the requirements that need to be fulfilled when installing a prototype.
An intensive searching of all related normative was performed, establishing in a particular way the specifications, requirement and conditions that each prototype should meet. This was based on normative from other renewable energy normative such as big wind technology or PV technology, also technical instructions from different distributed system operators (DSO) was considered.
Usually a commercial wind turbine is CE marked, this mark gives a series of guarantees that allow easier administrative procedures. During the project, project partners considered to obtain the CE mark, but the time needed and the kind of tests that the normative required (some of them are destructive), made this possibility unfeasible.
In order to overcome this barrier, it is crucial to develop a normative exclusively for small wind turbines (as other technologies already have), this would give support to this technology and would allow higher penetration of this technology into the market.

• Labeling standardization
SWT market is in a period of growth, as a consequence some frameworks are not well defined. In a similar manner to what happens in the normative framework, labeling procedure and the conditions under the labeling is performed are not stipulated by any accredited entity.
From the work developed within SWIP project it is concluded that the standardization of the SWT labeling is required. Therefore, the values provided by different SWT manufacturers can be compared in order to select the most suitable model which fulfil the necessities of the customer.
• Installation site
Due to the particular operation features of the SWTs, the location suitability takes relevant importance. In order to install the small wind turbine in the optimal location, it is required to follow the indications obtained by the wind resource studies.
Furthermore, it is proved that small modifications in the location or in the installation can produce important variations in the final results. Therefore, the modifications of the final installation from the initial project, shall be taken into account with the aim to estimate the real performance of the small wind turbine.
• Coordination effort
The intrinsic characteristics of the European projects imply that several partners are involved in the development of joint designs. From the perspective of companies, normally designs (i.e. mechanical design of the wind turbine...) are done by a single organization.
Within the SWIP project, different tasks targeting the same objective (i.e. mechanical design has been divided into several partners) have been carried out by different project partners from different countries. The coordination to make this work to be successful, taking into account that a prototype with moving parts was to be installed in a non-controlled environment, has required more effort in comparison if one single partner would have perform the whole task.

Potential Impact:
1.1.1. Potential socio-economic impact
Taking into consideration the SWIP project results, and its application to the Small Wind Technology industry, they would help to overcome the main barriers that this technology currently have and would help to a higher deployment of this technology.
The deployment of the Small Wind Technology has the potential to increase income and contribute to industrial development and job creation. Opportunities for value creation exist in each segment of the value chain, including project planning, manufacturing, installation, grid connection, O&M and decommissioning. Value creation varies along the different segments of the value chain. In the planning segment, for instance, the bulk of the value is created by engaging specialised companies to conduct resource assessments, feasibility studies, legal activities, etc. In manufacturing, value can be created in the sourcing of raw material, manufacturing sub-component, and assembling parts. The presence of other industries with similar processes can facilitate the development of a local wind industry (for example, power electronics industry that could absorb the converters manufacturing). The value created in the installation phase would directly depend on the nature of the wind turbine to be installed as it can considerable vary on the power and location of the installation of the wind turbine. Depending on the size of the wind turbine, these activities could be carried out by local Engineering or qualified professionals. The grid connection stage involves the engagement of grid operators responsible for integrating renewable generation as well as of local companies to undertake any infrastructure development to facilitate grid connection. O&M is a long-term activity that offers opportunities for domestic value creation, the deployment of this activities would require a mass deployment of this SWTs since one of the target of this technology is to lower the needs of O&M. Finally, the decommissioning of SWTs at the end of their lifespan can comprise recycling as well as disposal or reselling of components. Value is created in related recycling industries.
Further opportunities for value creation can be found in the supporting processes which complement the life cycle of wind energy projects, such as policymaking, financial services, education, research and development and consulting.
The extent to which domestic value is created along the different segments will depend on the overall level of a country’s industrialization. In the case where the country produces technology locally, many more opportunities for domestic value creation arise with the development of a local industry. As the industry develops, value creation increases along all segments of the value chain if the technology is produced locally and not imported.
A broad range of policies can affect value creation from deployment of wind energy. It covers policies to stimulate deployment, as well as those aimed at building a domestic industry, encouraging investment and technology transfer, strengthening capabilities, promoting education and training and research and innovation. Within the project, recommendations for policy makers have been proposed. Policies to support deployment are essential market-creating measures, as they trigger investments into the sector. The success of deployment policies in creating value also depends on the existence of other complementary instruments, such as those that aim to develop a local industry. Moreover, instruments that aim to facilitate access to financing are vital for value creation.
1.1.2. Main Dissemination activities
Communication and Dissemination activities have been ongoing since the beginning of the project, to ensure that stakeholders have been informed about the developments and to support post-project exploitation. The project has been presented at over 31 events and has had substantial promotion online via the project website, social media, news and videos. Early on in the project a visual and written identity was created for consistency of communication, and integrated into a broader communication plan to ensure that as many stakeholders could be reached as possible.
To communicate project aims, a website was established, as well as a leaflet and project videos. Press Releases have been produced and distributed throughout the course of the project. Substantial effort was made to present the results of SWIP at the EWEA Annual Conference in September 2016, as world’s largest wind energy event. In total, one poster presentations and five oral presentations were given.
Policy Implications arising from the project have been drawn up and presented to policymakers at the European level through a final Policy Event held in Brussels.
The Dissemination and Communication work of the project should actively support the future exploitation of the project results, by raising awareness of the work that has been done. The project identified technical barriers, regulatory barriers and a lack of standardization to follow as major barriers to the mass deployment of SWTs. The dissemination work both promoted SWIP’s technical developments, as well as promoting new value chains in general. Specific effort was made to communicate with policymakers, to make the case for future policy support as well as to promote awareness of the barriers this technology has for its deployment.

1.1.3. Exploitation of results
Defining a market- and customer sensitive exploitation strategy is of key importance in order to bring SWIP’s aforementioned Exploitable Results to value for society and the European economy. During SWIP, a predefined method has been followed by the consortium as a whole and with individual consortium members to achieve a shared exploitation strategy in which all exploitation interests are covered.
The decision has been made to not pursue the exploitation of the three SWIP wind turbines (2.4 and 20 kW) as a whole. Considerations behind this decision were based on barriers such as a lack of a sizeable production facility. However, the market opportunities of the separate components and revolving products/services were apparent. The market and clients have played a key role in the substantiation of these market opportunities. Following the current insights that the Design Thinking philosophy have brought us, technology development should only take place within the framework of and with sensibility for the client’s needs, a viable business strategy, customer value and market opportunities. After all, there is no substantiation to invest in the technological & business development of a technology unless it is underpinned that it adds value for a subsequent partner in a certain value chain. Contact has been established with relevant market parties to get a solid first indication for the need and willingness to pay for each and every module of the SWIP wind turbines and a market study has been performed to gain actual insight in the current ins and outs of the Small Wind Turbine market.
The main objective of SWIP’s exploitation strategy is to underpin and detail WHY, HOW and WHAT IS NEEDED to bring each of the Exploitable Results successful to market by WHOM and what BARRIERS need to be tackled. To answer the WHY question, as framework to determine the best way towards the market for every Exploitable Result, the ‘6 typical Exploitation Routes’ method has been used.
For SWIP, these typical exploitation routes and the following action plans are used as a basis for every Exploitable Result. A brief explanation of the six routes to market are given:
Internal partner exploitation
Results from the project are used for further research and or future projects within the company itself. Results are not sold, but are meant solely for internal use.
License Agreement / Technology Sales
After obtaining IPR on project results, the rights to use this IP can be licensed or sold to parties interested in using this IP. In case of a license, the original IPR owner keeps the IPR but “allows” others to use the IP in exchange for a fee. Licensing allows for a periodic cash flow. In case of a technology sale, the IPR transfers from the original- to the new owner. Technology sales can create a big revenue at one instant, instead of periodic income. Every license agreement or technology sales requires a custom-made approach.
When development of a product or service is pursued, one can choose to do this in a spin-off company. IP can be transferred or licensed to the spin-off, which can then fully focus its attention and resources on development of the product or service.
Embedded Product
Exploitation can be done through production of an embedded product. This embedded product has no functionality on its own, but needs to be integrated with other technology into one final product. The sales to end-users is done by the company that brings the final product to the market.
New Product
If the product has functionality on its own, it can be sold as a new product. Difference with an embedded product is that a new product can be sold directly to customers who are looking for the functionality the product provides.
All human embodied value propositions created from SWIP results are part of the consulting exploitation route. Human embodied means that human expertise is necessary for the value proposition. This can be engineering, training, consulting etc. Humans are needed to interpret SWIP results and apply them to the situation of a customer and to write an advice. Education is excluded from this list however. Physical products are often not human embodied. Once you bought a hammer you are not dependent on the firm who sold the hammer if you want to use it.

List of Websites:
No. Participant name Country Website Contact
1 Fundación CIRCE - Centro De Investigación de Recursos Y Consumos Energéticos (CIRCE) Spain Leo Subías
5 METEODYN SAS France Julien Berthaut-Gerentes
6 DNV GL NETHERLANDS B.V. Netherlands Koen Broess
7 Greenovate! Europe (G!E) Belgium Katharina Krell
8 SAL LIMITED Ireland Brian O´Brien
12 ETULOS SOLUTE SL Spain Fernando Aznar