Excellence in Professional Services

Accredited as Testing Laboratory following ISO / IEC 17025 for wind resource and energy yield assessment incl. site assessment and power performance measurements conform to IEC 61400-12-1, MEASNET and FGW standards.

Mandatory in complex terrain

In cases of complex terrain, where power performance measurement or power curve verification shall be performed, site calibration is the enabling tool.

During power curve verification in flat terrain an undistorted, free sector is determined that lets assume that the wind speed measured at the wind mast is precisely the same free flow wind speed that hits the wind turbine at hub height, just before blockage effect of the wind turbine comes into force.

That relation of undistorted, free flow wind speed between mast and turbine cannot be maintained in complex terrain, though, as the wind speed measured at the wind measurement mast will be affected by topographical and maybe roughness characteristics of the terrain. Meaning that at the wind turbine another wind speed is present as if compared to the wind mast.

For power curve verification in such (semi) complex situations two masts are used to measure the wind and to subsequently derive the relationship between both masts. Having derived the proper statistical relationship enables removal of one mast, and putting a wind turbine exactly at that same position where the measurement mast was located before. This procedure enables to measure the power performance of a wind turbine (P-V curve) even in very complex terrain, mimicking the exact wind speed for the point of the wind turbine by site calibration following 61400-12-1.

During any such procedure ... of course also the uncertainties likewise need to be considered and assessed in a bankable way.

Cost saving during normal project development with multiple measurement masts

During usual wind project planning, site calibration offers an appropriate solution to save costs by imitating measurement masts and reducing the costs for further wind measurement masts installed.

In case of huge wind farm areas or (semi-) complex terrain, often several wind measurement masts are recommended in order to assess the necessary degree of certainty requested by most banks and investors in order to offer (more) attractive financing conditions.

As a rule of thumb we recommend: each multiple of about 40 MW capacity to be installed (with some degree of variation depending on the site complexity, turbulence etc.) demands an additional measurement mast, in order to assess the wind resource and uncertainties at an acceptable level of accuracy.

Do not stress the budget! Alternating mast techniques can be applied. With a given amount of masts at a fixed position, other masts can change their location with a frequency of about 4-6 months. Advanced correlation techniques between the fixed mast(s) and the alternating masts allow mimicking and imitating the wind resource at each of the alternating masts' positions and heights, prolonging with acceptable uncertainty the measurement to the same period as measured at the fixed mast. Each alternating mast could therefore replace up to 3 fixed masts during one-year time.

Depending on the site characteristics as well as in cases where an ex-post site calibration may be impossible (e.g. as a WT is already operating and economic constraints may oppose dismantling of that WT for site calibration), we perform Power Performance Verification by aid of the nacelle anemometer as described in IEC 61400-12-2.

Preferably the Nacelle Transfer Function (NFC) of another WT and/or site can be taken into account during that process, significantly lowering measurement term and cost.

In general the procedure reduces the uncertainties linked to the wind database investigated for the objected area by increasing the measurement period for each single measurement point in combination with multiple measurement points.

Optimally introducing & managing increased shares of intermittent, volatile re-sources in sophisticated interconnected networks or stand-alone hybrid systems.

Model validation based on final design parameter:

We provide sophisticated models for each energy generation technology in the hybrid or interconnected systems and utilize appropriate tools to model individual components or entire systems. The models will be parameterized based on the final systems to be installed and respecting the case-to-case necessities.

Design and simulation of operational scenarios for compensation and critical system mode identification:

Several operational scenarios based on varying sources, amount of generation and loads, operating modes and parameterization can be simulated and evaluated. Based on the simulation results, the operational scenarios will be evaluated in order to determine the most suitable operation modes, patterns and policies of the future hybrid energy system, taking into account conditions and framework parameterization. Also edge scenarios that may be seen as 'critical' would be detected and analyzed in order to define the technical measures for prevention.

Any analysis will be accompanied with recommendations that perfectly fit to the clients situation and needs. ProfEC standard and national standards and codes.

Accredited as testing laboratory following ISO / IEC 17025 for wind resource and energy yield assessment, including uncertainty assessment conform to ISO / IEC 61400-12-1, MEASNET and FGW standards.

Bankable determination of uncertainties is a key component for project financing and the optimization of financing conditions.

Our clients, especially banks, investors and project developers, trust on our expert opinions and bankable reports. Our assignments are presented to the financing banks and to wind turbine manufacturers, investors, insurance companies and underlying contract terms. Therefore, we consider it the most important to not only measure the wind resource as precise as possible, but also to determine the involved uncertainties by advanced and most recent methods, which are accepted and even determined for the wind resource as well as the energy yield potential.

In general uncertainties can be decreased by calibrated equipment installed in accordance to IEC 61400-12-1 and to MEASNET standards. Also the height of measurement matters, as well as the amount of measurement points and the duration of the measurement campaign. The rest and the measurement period. Assessing the 'wind resource' as precise as possible is the most important parameter to yield the uncertainties.

Assessing highly relevant uncertainties by application of advanced techniques and procedures:

Most innovative and unique during our uncertainty assessment is that we concentrate very much on the understanding and the quality of variation from the existing data. The data is analyzed from the point of view of terrain complexity (Weibulli fit), which rarely is considered among the wind energy sector yet.

Therefore, we provide data and reports based on applying Global fit and mainly huge uncertainties attached to this standardized and widely accepted procedure.

With lower uncertainties to higher P75, P90 and P95 values, which balance financial risks of investors:

Derived from the uncertainties, the probability of exceedance with given levels of confidence P50, P75, P90 and P95 are depicted as important parameters for financial project evaluation and risk assessment. Banks and investors, which will adopt the Term Sheet for loan provision by an appropriate Equity / Debt ratio will be able to offer more attractive financing conditions in reflection.

It is all about quantifying the uncertainty of annual energy yield prediction:

Investor decisions are commonly based on P90 and P95 values, which balance financial risks. Larger P90 documentation and sensors, as well as accurate mounting and long-term data assessment, are considered for decreasing the uncertainties. The lower the uncertainties the difference between the P90 and P50 level of energy generation. The lower involved uncertainties are, the smaller the difference between P50 and P90. Low uncertainties directly increase the value of a project. The higher the P90 value, the more attractive leasing to more attractive financing conditions granted.

ProfEC Ventus performs an accredited service regarding analysis and assessment of losses in accordance to the Technical Guideline FGW TR6 regarding reliable reference standard.

Losses reduce the net feed-in of energy and can become critical for the financial stability of projects.

Losses principally describe the difference between the useable gross energy yield produced by the wind turbine and the net energy delivered to the grid and sellable at the point of measurement for grid injection (mostly at the point of common coupling (PCC)). Location of the measurement determines parts of such systematic and hence the losses, resp. the escable income related to losses, vary either.

Infrastructure, within which wind energy is embedded, as well as requirements from grid operators or even environmental factors, can influence the systematic losses more complex and hence the likeliness of technical and non-technical losses increases.

Why it be that there is too much intermittent renewable energy penetrating capacity grids, also, one of new arising reasons could be the application of the so-called 'Environmental or social restrictions (bird migration, bats, noise, shadow etc.) to noise vibrations, in which a wind turbine is forced to stop or to reduce its output.

Next to losses as a result of regulations, there are losses related to turbine standstill times for repair, maintenance and malfunctions, such losses should be assessed, qualified and quantified.

To mention only a few of them, we perform loss assessments related to most importantly:

• Wake effects and obstacles causing a change of the wind field characteristics across the rotor plane
• Availability of the wind turbines and deviations repair and maintenance times and technical failures
• Electrical efficiency regarding self-consumption of the wind turbines, the wind farm and turbine power electronics (e.g. the transformer etc.)
• Power performance and efficiency of the WT with regards to site specific characters and cut-off hysteresis

Knowing precisely the losses prevents wrong expectations:

We assess losses following most modern approaches and in compliance with FGW TR6. A realistic and accurate loss assessment, avoiding too optimistic as well as too pessimistic assumptions, helps the investors to derive realistic project budgets, avoiding too high expectations, strategy, reducing equity capital ratio, interest rates and financial guarantees to be provided by the lender.

• Environmental losses as icing, site access, temperature caused malfunctions etc.
• Power reduction due to sector management (e.g. caused by radar or turbulence thresholds), grid instabilities, power quality (e.g. flicker, harmonics), and marine mammals, noise, shadow flicker, etc.)

Assessing the probability of unforeseen losses enables to safeguard a solid cash flow prognosis:

Unforeseen losses, as well as inaccuracies and concerns, can be derived from regulations that apply to specific situations. Assessment and quantification are comparatively easy in such cases.

However, there are losses that do occur spontaneously, appear and disappear, that software recall and software malfunction of wind turbines, or the unexpected behaviour of a given power curve at a particular site. Such losses can be derived based on empirical findings and long term experience, which some of our specialty working fields.

Taking such loss scenarios into account helps to prevent a cash flow collapse in critical situations and does safeguard a solid cash flow prognosis. In addition, does the project operator to form accordingly qualified financial reserves.

ProfEC Ventus supervises setup and establishment of production floors for manufacturing small wind turbines for rural electrification by aid of a simple, reliable and robust design.

Optimal and reliable performance especially matters at rural context:

We are providing professional and scientific assistance for the development and optimization of small wind turbines for rural electrification applications. Thereby we look at the product development, engineering, manufacturing and testing of individual components, subsystems, the testing and certification of entire wind turbines.

As a result, costs of production are reduced, making the turbines affordable in most rural context.

Knowing precisely about key components makes the turbines affordable in most rural context. Blades, the drive train, the generator and the electrical components have been contracted for governance and supervision during establishment of an entire standardized manufacturing floor with the superior objective to produce small certified wind turbines. During our design and development, we are also taking into account internationally accepted IEC norms and ISO quality standards, most remarkably:

• IEC 61400-2: 2013 Ed 3.0: Wind turbines - Part 2: Small wind turbines
• IEC 61400-11 : 2012 Ed 3.0: Wind turbines - Part 11: Acoustic noise measurement techniques
• IEC 61400-12-1: Power Performance measurements of electricity producing wind turbines
• ISO 9001:2008: Quality management systems — Requirements

Learnt from the big, applied to the small:

We do assay on the improvement of the technical design, efficiency, aerodynamic, control, durability and quality of wind turbine components for small wind turbines. Thereby we apply our expertise to a reliable system production, yielding internationally accepted and proven wind turbines as product.

Of essence is an economic and reliable design for rural applications:

In rural and remote locations high reliability of wind turbines is essential. Especially the initial procurement costs as well as later on occurring life cycle costs for rural electrification. Also of importance are operational costs as well as the spare part availability, and the presence of skilled personal to provide repair work for turbines in case of any failure.

Knowing about this importance for rural electrification, we have been adopting a concept of a small wind turbine that could be built anywhere in the world by local companies, generating local jobs and skills. While the reliability that can be operated, maintained and repaired locally and at local costs.

From the wind turbine tower via the charge controller to the battery, all can be acquired or manufactured in a regional context, becoming independent from the import of goods from industrialized countries, which mostly do not meet the affordability and maintainability rural electrification and poverty alleviation.

At critical factor must also be seen the chance for local technicians conducting maintenance and repair of the wind turbine themselves. This finally is a key that enables the sustainability of the turbine and that it is needed to fly-in technicians or spare parts from abroad.

We integrate the optimization of components, systems and provide training to local technicians to enable a complete local service for manufacturing, operation and repair.

The overriding objectives of our consulting services are to use small wind turbine design and component optimization are:

• yielding local low cost production
• high reliability
• high system efficiency
• high system availability as well as
• compliance to internationally accepted production standards
• compliance to internationally accepted safety norms
• compliance to internationally accepted quality of performance.

Accredited as acknowledged testing laboratory following ISO / IEC 17025 for power performance measurements and power curve verification of wind turbines according to IEC 61400-12-1 and MEASNET Power Performance Measurement Procedure.

Profitable wind resource is available but where remains the prognosticated power generation?

A power curve describes the power output generated by a wind turbine as function of the wind speed that the turbine rotor is exposed to at hub height.

Both, the wind turbine manufacturers offering a product to potential clients or developing a new product prototype, as well as the clients or banks financing a wind farm project and investing in a profitable power output of the wind turbines, have a common interest to ensure that the considered power curve is met during operation and under real conditions, and that the power curve is not only a calculated value on a data sheet.

Power performance measurement and power curve certification are the appropriate means to prove this.

To verify the power curve, we perform an accredited power curve measurement in compliance according to internationally accepted norms and standards as

• IEC 61400-12-1
• IEC 61400-12-2
• IEC 61400-1
• FGW TR2
• MEASNET Power Performance Measurement Procedure

We perform power performance and wind measurements for hub heights up to 160m by aid of measurement masts and we do perform higher measurements by aid of LiDAR and/or SODAR remote sensing devices and techniques.

Power performance: a matter of sales contracts, advertising brochures and project cash flow expectations:

Also banks and investors, having an interest in the success of a wind project, may request for power curve verification. Typical needs for a power curve measurement and verification exists especially if

• a wind turbine, or even worse the entire wind farm, do not meet the warranted power production values (typically 95 % availability and 95 % of the power curve prognosticated).
• if in such cases neither analysis of operational data nor due diligence of the on-site available wind resource potential could explain the underperformance, a power performance measurement and power curve verification is the only standardized and accepted way to verify the turbine's actual power performance.

After the 2 year warranty period provided by the turbine manufacturer, any underperformance of the turbine will be fully transferred to their actual client. Just before that moment the client or investor's may want to have certainty that the wind turbines still are as good and as powerful as they were promised during the turbine purchase. If not, liquidated damages may but especially as agreed on in the sales contracts.

Any shareholder wants to have full certainty and guarantee that the product he bought is really meeting the expectations and promises negotiated and agreed upon. If a wind turbine does not perform as guaranteed, an appropriate wind turbine sales contract considers good performance guarantee and warranty conditions in case of wind turbine under-performance.

In this end, if a wind turbine does not yield the greatest power performance, compensation measures may be agreed upon. Thereby, the turbine manufacturer as well as the wind turbine owner/investor may want to have certainty that the wind turbines still are as good and as powerful as they were promised during the turbine purchase.

We do assist our Clients during contract negotiations and consulting in questions of performance conditions (e.g. high wind turbine availability and site specific energy yields) and appropriate guarantee conditions (e.g. financial compensations in case wind turbines fall behind any expectations) at a reasonable price. Moreover, we provide assistance in technical and financial accepted calculations in order to determine the magnitude of financial damages in consequence of wind turbine under-performance.