PHOENIX CONTACT | UPDATE SPECIAL - The Phoenix Contact innovation magazine

FA C T S A N D F I G U R E S Location Loss 15 % of all wind turbine generator sites in Austria are “cold climate” sites 15 % of the yield of annual power generation is lost due to icing 7 to 14 days the average days per year that a wind turbine generator ices up in northern Germany; at higher altitudes this can reach more than 30 days Ice throw/fall 0° to -20°C the temperature range in which clear ice, rough ice, or rime (ice) forms € 400,000 loss of earnings per year with 14 days of downtime for a small wind farm with 12 turbines Maximum ice throw distan c Ice throw = falling pieces of ice from a running wind turbine generator e of a r u n n i n g s y s t e m Ice fall = Falling pieces of ice from a stationary wind turbine generator (partly infl uenced by winds) I c e f a l l Seifert formula Hub height = 120 m Rotor diameter = 140 m (Hub height + rotor diameter) x 1.5 = Maximum ice throw distance (120 m + 140 m) x 1.5 = 390 m 390 m Effect of icing on wind turbines Accidents Service/ maintenance Rotor imbalance Safety Technology Finances 0 known cases of personal injury due to ice throw/fall from 29,000 wind turbine generators in Germany (status 2017) Ice throw/fall Power loss Material fatigue 2 UPDATE SPECIAL The Phoenix Contact innovation magazine 50 incidents of serious damage to wind turbine generators per year according to VdTÜV

S I G N P O S T We know ice Dear readers, It is not presumption, but certainty that should guide our actions. And certainty is exactly where we are coming from when we introduce you to the innovative ice detection system from Phoenix Contact over the following pages. Wind power is one of the key technologies in the fi ght for climate-friendly power generation. This is leading to wind turbine generators being located at latitudes and altitudes where ice is more likely to form on the rotor blades. The shutdowns necessary as a result of this formation results in an irregular power supply and reduced yields. The ice detection system from Phoenix Contact is a reliable, durable way to counter these adversities with technology, and is easy to retrofi t. But read on and fi nd out for yourself! Jörg Hildebrand, Industry Management Renewable Energies With the blade runners Experienced industrial climbers install the ice detection system from Phoenix Contact above the treetops of the Swabian Jure | 04 BACKGROUND Where is icing a threat? TECHNOLOGY How does the plaster work? IN PRACTICE How effective is the system? Ever higher – this not only applies to the towers of the wind turbine generators, but also to the latitudes or altitudes of the installation sites. A Geographical and technical overview | 08 The sensors of the ice detection system are energy-autonomous, transmit their measured values wirelessly, and measure the real situation on the blade. A look at the adhesive innovation carrier | 12 Is it just pure theory and glossy marketing copy? Practical experience and independent long-term tests show whether and how effectively capacitive ice detection works | 16 The Phoenix Contact innovation magazine UPDATE SPECIAL 3

Phoenix Contact works with specialized industrial climbers Installation and commissioning is performed in a team Plasters help One of the strengths of the ice detection system from Phoenix Contact is the ability to retrofit the sensors. We accompanied the specialists on their work at lofty heights. I t is cold, and the sun is making its way over the tops of the trees in the Swabian Jura. Selvin Keller pulls up his collar, puts his gloves on, and yanks on the starter rope. The four-stroke engine that powers the rope scooter starts up with a rattle. With a satisfied grin, the industrial climber lets himself be of around 85 meters. It is at a standstill and waiting for the expert to do his work. His job: Applying ice detection sensors to the blade. Suspended on ropes, he will spend around an hour concentrating, first roughening the surface of the blade, priming it, and then carefully applying the sensor in the form of a hoisted upward by the special apparatus. giant plaster. Above, in this case, is one of the rotor blades of a wind turbine generator at a height Continued on page 11 à The Phoenix Contact innovation magazine UPDATE SPECIAL 7

80 % less ice-related downtime is possible. B A S I C P R I N C I P L E S 200 the number of extra hours a reference system could run in one winter in southern Germany. Ice-cold facts The scene is typical for the ﬁ eld of application of the ice detection system from Phoenix Contact. The wind farm where Keller and his team are working is located at a high altitude. The Swabian Jura is not only very windy, but in the cooler season it is also quickly exposed to temperatures at which ice crystals can form on the rotor blades of larger wind turbine generators. There are big regional differences when it comes to ice formation on wind turbine generators. Particularly in what we call cold climate regions, a wind turbine generator (WTG) has to be ideally equipped to manage ice build-ups on the rotor blades. A distinction is made between two types of cold climate regions: On the one hand, there are the areas where particularly low temperatures occur because they are located at latitudes very far to the north in the northern hemisphere or to the south in the southern hemisphere. As a result of the global expansion of the wind power industry, these regions are becoming increasingly attractive. On the other hand, there are areas where atmospheric icing is more frequent, for instance because they are located at particular altitudes. Here, the rotor blades of ever-larger wind turbine generators streak through low-hanging cloud layers and ice up, even when there is no ice or snow on the ground. 8

Regions at risk of icing throughout the world > 30 days < 0 ºC Against the backdrop of the increased global expansion of wind power, these climatically more diffi cult locations are also being used increasingly. To be able to classify how much icing is to be expected, the IEC icing classes are used (IEC 61400 is an international standard for wind turbines published by the International Electrotechnical Commission (IEC)). As long as the formation remains at just a few crystals, neither the wind turbine generator nor its operators are bothered. But if this icing increases, the scenario changes: • A wind turbine generator loses up to 15 percent (see interview starting on page 16) of its potential annual energy output if it is not de-iced. This is because ice changes the aerodynamic properties of a wind turbine. From an ice thickness of around 1 mm, the effect becomes signifi cant. If the system continues to run, then it does so with a reduced yield. Since defrosting takes a disproportionately long time, wind turbine generators are usually shut down as a preventive measure when ice formation is imminent. • The formation of ice is uneven. This leads to imbalances in the rotor blades, which transfer their forces to all components of the system. The stronger vibrations put a lot of stress on the material in the system and lead to a reduced service life. • The ice may break off in pieces. This ice shedding is a potential hazard to people within an area of several hundred meters around a wind turbine generator. The ice chunks can weigh between a few hundred grams to several kilograms. A system that cannot be de-iced must be shut down in the event of ice formation. These downtimes naturally lead to reductions in yield that are sometimes signifi cant. These represent fi nancial losses that quickly ensure that technical measures for ice detection and prevention thus become profi table. • Ice detection systems ensure profi tability and yield • Extend the service life of a system • Ensure the operational safety of the system. à BA SICS

Ice detection – systems at a glance Naturally, this does not result in a particularly realistic assessment of the situation on the blade and thus, out of necessity, becomes a highly conservative interpretation of the measured values in order to avoid possible risks. Result: The system is shut down earlier to be on the safe side. And: An automatic restart is not possible, because it cannot be determined whether ice has stopped forming on the rotor blades. The advantage of nacelle-based systems is the perceived low procurement price. Blade-based ice detection Blade-based measurement systems measure ice build-ups directly on the rotor blades. Here, a distinction is made between two measurement methods: • Measurements outside, directly on the rotor blade using capacitive sensor technology, which directly detects ice and measures its thickness. • Measurements inside the blade, using fiber-optic or piezoelectric methods, with the formation of ice being calculated based on the changes in the vibration behavior of the rotor blade. There are now several ways to detect the formation of ice. The individual systems for ice detection use different technologies: • Measuring the ambient temperature • Measuring the ambient temperature and humidity • Anemometer comparisons • Optical camera systems • Changes in the power characteristic curve, for example the power output of the WTG • Measuring the ice directly on the rotor blade (vibration-based or by resistance measurement) The key is where the measurements are taken. The difference between ice forming on the rotor blade and ice forming on the nacelle is often greater than expected. Factors such as geometry, dimensions, movement, and flow velocity mean that completely different climatic influences exist on the blade that are not present at the weather mast on the nacelle. The fact that the systems listed vary greatly in their accuracy mean that they have differing influences on the yield, but also play an important role in generator safety considerations. As a result, two technical solutions in particular have become established on the market: Nacelle-based ice detection and blade-based ice detection. Nacelle-based ice detection Nacelle-based systems are, conventionally, mounted on the WTG weather mast and measure specific meteorological parameters to determine the possibility of ice accumulation. Specific technologies, such as comparing two anemometers, measuring the humidity, or ultrasonic ice detection, are used for this. Regardless of which version is used, none of them measure the ice accumulation on the rotor blade, but rather at a location where entirely different conditions prevail. 10 UPDATE SPECIAL The Phoenix Contact innovation magazine

I N S TA L L AT I O N Selvin Keller has finished installing the first ice detection sensor. The frost-free temperatures are allowing installation late for nothing. He seeks out the next application point. The locations where the seven sensors are to be positioned on each rotor blade have this year. If temperatures drop below freezing, been discussed and determined in detail the adhesive no longer bonds to the roughened beforehand with the experts from the Phoenix blade. These would be poor conditions to Contact Wind Team. If one of the sensors that guarantee at least ten years of adhesion life. But despite cool temperatures and nightfall, installation is possible without any problems. transmits its data to the control system in the nacelle should fail, this does not mean the entire system does too, because the redundant The industrial climber cleaned and roughened sensors continue to ensure seamless ice the blade at the installation point, then applied an activator and, finally, attached the sensor. He carefully ensures that no bubbles detection even then. A PLCnext controller, a powerful industrial controller, is installed in the tower to record are formed during gluing and pressing. The and evaluate the data and forward it to the edges are sealed in addition. control room. Keller moves carefully and skillfully across the rotor blade surface. In the wind industry, the specialists are not called blade runners Continued on page 14 à The sensors can be installed above temperatures of around 6 degrees The Phoenix Contact innovation magazine UPDATE SPECIAL 11

B A S I C P R I N C I P L E S The intelligent plaster Nils Lesmann, product manager in the Phoenix Contact Wind Team, explains the innovative ice detection plaster in detail: The system has been developed for application on the outside of the rotor blade. The elements of the sensor plaster are • The carrier foil • A power supply unit consisting of solar and battery cell • The sensor itself, and • A wireless antenna that transmits the measured data to the Phoenix Contact controller. The foil, which we call Windtape, comes from the manufacturer 3M. It is made of extremely tough, abrasion-resistant polyurethane elastomers and can withstand the stresses on a rotor blade for years. The conditions are extreme on the blade: UV radiation, enormous temperature fl uctuations, humidity, and of course ice crystallization, dust as an abrasive element, and permanent centrifugal forces. Accordingly, care must be taken during application. The edges of the Windtape are protected in addition with a special two-component edge sealer that guarantees years of durability. The self-suffi cient energy supply unit consisting of a fl exible solar cell and the powerful battery cell can manage for up to 1,000 hours without direct sunlight thanks to its buffer function. It is also completely maintenance-free for years, supplies the sensor, its electronics, and the integrated wireless antenna with power, and thus allows wireless installation and, in particular, retrofi tting. The sensor measures the ice thickness directly using the fi eld strength. The change in impedance on the surface of the sensor provides information on the icing and its thickness. In addition, the temperature is measured. This also allows an assessment to be made on the absence of ice, thus Ice detection sensor The actual ice thickness is measured via impedance measurement Solar cell Wireless and durable power unit Wireless antenna Wireless data transmission eliminates the need for a cable harness Windtape The 3M fi lm defi es the elements for many years 12 UPDATE SPECIAL The Phoenix Contact innovation magazine

Nils Lesmann (right), Senior Project Manager in the Phoenix Contact Wind Team, is thrilled by the system “The entire system is ideal for retrofi tting.” Nils Lesmann, Senior Project Manager, Phoenix Contact Wind Team enabling automatic turbine restarting. This is an important part of the system, especially in areas where icing is a regular occurrence, as it eliminates the need for technicians to travel to the site, which is time-consuming. The raw data is transmitted by a wireless antenna directly to the turbine controller which evaluates, interprets, and transmits the data to the farm operator’s control room. Due to the durable and stable wireless solution, cabling is not necessary. The complete system is therefore also ideally suited for retrofi tting in existing wind turbines. 1000 the number of hours the ice detection sensor can transmit, even in total darkness, without sunlight. Costs and benefi ts Using an ice detection system directly on the surface of the blade can reduce downtimes by up to 80% each year. For a reference system with a nominal power of 3 MW in southern Germany, ice- related downtime could be reduced by 200 hours in one winter, resulting in an additional yield at a remuneration rate 8 cents per kWh of around € 23,000. Because the system is also certifi ed for automatic restart (in accordance with DNV GL), system downtimes due to ice accumulation can be reduced to an absolute minimum. Maintenance work including a time-consuming on-site visit is not necessary. Another advantage is that it is easy to confi gure the sensors via app. The app guides the installer through the installation process on site. The installers can document the correct installation of the sensors with photographs. The app also extracts the key sensor data from these photos and transfers it to the WTG evaluation unit. In this way, the confi guration is signifi cantly easier and the technicians are spared time-consuming work. 13

 Mr. Bülter, Mr. Pukall – are you are the contacts for Phoenix Contact customers in Germany when it comes to ice detection? Björn Bülter: That’s right, we have been part of the team at Phoenix Contact’s German sales subsidiary for several years, dealing with all topics related to renewable energies. Our focus here is the fi eld of wind power, which also makes us the contact for our customers when it comes to ice detection.  How long has the company been dealing with this problem, and what is our approach to solving it? Oliver Pukall: We presented our solution for ice detection for the fi rst time in an exhibition at the Wind Energy trade fair in Hamburg back in 2018 – with an outstanding response at the time. Since then, we have worked meticulously to make the system fully production-ready, as well as to fi ne-tune services and processes so that we can offer the system including turnkey installation. At that time, the approach of detecting ice via capacitive measurement directly at the location of the event was completely new and extremely exciting for everyone involved. This was because all other systems do not measure the ice, but only changes in the wind turbine, which combined with weather data is meant to provide indirect ice detection.  After a large number of tests, the ice detection systems from Phoenix Contact are running in real- time on some installations, and there are initial tangible results. How has this method of direct ice detection by sensors proven itself? Bülter: Since the launch, we have been able to test our ice detection system in tough everyday conditions on a large wind turbine in a wind farm in the Swabian Jura, among others. The fi rst results were seen immediately: Our system is quick and easy to install and ready for operation immediately after installation. By comparison, vibration-based systems sometimes require a learn-in phase of several months. In addition, we have been able to demonstrate the self-suffi ciency of our ice detection system. No data from the WTG controller is required. The direct detection of ice means that it is no longer necessary to extrapolate potential ice formations indirectly through various measured values. This is another reason why retrofi tting is much easier, because no other system needs to be coupled. In addition, although the system was not installed until mid-December and we had a historically mild winter, the fi rst ice events were detected in the fi rst winter of 2019/2020, with comparisons tending to show less downtime with our system.  Did the system work without issues from the beginning? Bülter: Yes, the system worked without any issues right from the start. Only the position of some sensors placed “Up to 300 kilos of ice mass formed on the rotor blades.” Oliver Pukall, Key Account Manager Renewables Wind Power Phoenix Contact The Phoenix Contact innovation magazine UPDATE SPECIAL 17

“The potential for our system is enormous and will only increase.” Björn Bülter, Key Account Manager Renewables Wind Power Phoenix Contact Björn Bülter is well-known in the German wind power industry by the service provider was not quite ideal. This led us to develop an app that guides the rope climber through the installation and documents the installation results in the same move. Pukall: At this year’s Winterwind, the industry’s most important trade fair when it comes to winter conditions, a comparative test of four different systems was presented, conducted by the independent Meteotest AG Pukall: (Grinning) well, the results fully confi rmed our expectations. All four systems were reliably able to detect this ice formation. In fact, our system was the fi rst to detect ice formation. But how they then handled that data was spectacularly different. The three vibration- based systems would have stopped the system too early, and the times were only 90 minutes apart at most. Our system would not have stopped the wind turbine until a company based in Switzerland. The ice detection systems good two days later. were all blade-based, not nacelle-mounted systems. The The actual situation on the blade was continuously wind turbine on which all four systems were installed was a Vestas V90 setup in Sweden. Three of the systems were vibration-based; our recorded via camera. This demonstrated that this later shutdown did not pose a safety risk, because the actual thickness of the ice layer only started to grow system was the only one based on direct ice detection. once our ice detection system stopped the wind turbine. The test stretched out for more than three years. In total, the wind turbine generator provided electricity for 5,700 hours. There were more than 60 individual icing situations, accounting for a total duration of just over 2,500 hours. In some cases, up to 300 kilograms of ice mass formed on the blades.  Those are harsh conditions indeed. Will wind power generation there ever be proﬁ table? Indeed, the ice formed very unevenly on the blade. The value specifi ed by the standard for shutting down the system for safety reasons was actually reached very late. But since the vibration-based systems have no idea about what exactly is happening on the blade, they were much more likely to respond by shutting down. First to detect, last to stop – good confi rmation of our system’s abilities from an independent body. 18 UPDATE SPECIAL The Phoenix Contact innovation magazine

I N T H E F I E L D  What technical knowledge has Phoenix Contact been able to adopt from this experience for other systems? Bülter: It has been confi rmed that the ID-S ice detection system works autonomously and regardless of the wind turbine manufacturer or blade. We have learned from the coordination problems with the installation service why we came up with the idea of the app and, thanks to our own developers, we had it ready very quickly.  How many towers do you estimate there are that potentially need this ice detection system? Bülter: In Germany, an ice detection system is now required by building permit for all new systems provider, which in some cases resulted in less than ideal sensor positions, and have developed the Blade Intelligence App as a solution. throughout the country. For existing systems, it often comes down to a site-dependent decision. Here, it depends on how often and how long the WTG is stopped Pukall: The development of the app is a fantastic because of detected ice. In addition, the system must example of Phoenix Contact’s innovative strength. We still have a certain amount of its lifetime remaining, were able to put the system into operation immediately in the Swabian Jura, but noticed during the fi rst review of the data that some sensors were not in exactly the right position. However, trial-and-error is far too expensive when working with industrial climbers on wind turbines that have been shut down. No operator likes that. That is so that there is a corresponding return on investment. With around 30,000 WTGs onshore in Germany, I conservatively estimate that this is true for at least 1,000 turbines. And that is in Germany alone.  Björn Bülter Key Account Manager Renewables Wind Power Dipl.-Ing. Electrical Engineering 44 years old bjoern.buelter@phoenixcontact.de Oliver Pukall Key Account Manager Renewables Wind Power Energy Electronics Technician 47 years old oliver.pukall@phoenixcontact.de CONTACT CONTACT The Phoenix Contact innovation magazine UPDATE SPECIAL 19

in the rotor blade The ice detection system complements the modular product range surrounding Blade Intelligence, which Phoenix Contact is using to take the monitoring and availability of wind turbine generators to a new level. Blade Intelligence is what Phoenix Contact calls its system for monitoring the rotor blade in wind turbine generators. The term describes several technologies, both modular and combined, used in new or existing systems. In addition to ice detection, Blade Intelligence also includes systems for load measurement and lightning current measurement. Load measurement is becoming more relevant against the backdrop of ever-larger systems and thus ever-longer blades. The dynamic forces are measured via strain gauges that are glued to the inside of the rotor blades close to the base of the blade. The system is suitable both for use in new systems and as a retrofi t solution Time and again, lightning strikes cause damage to the rotor blades and result in electronics failures. With the lightning monitoring system, it is no longer necessary to replace protective devices “just in case”. The LM-S Lightning Monitoring System detects and analyzes the lightning surge currents, thus determining the actual load on the system. Uniﬁ cation for the system The modular design of this solution allows the individual solutions to be combined as needed depending on the requirements. Sensors developed specially for installation on the rotor blade provide all of the data necessary for processing in a shared evaluation unit. Extensions with additional sensor technology are possible at any time. The data from all sensors is visualized on an HMI web panel. The intuitive interfaces give you quick access to all functions and provide you with a complete overview of what’s going on with each and every rotor blade. With digital support via app for installing the sensors, working on the blade becomes even easier. Right from the start, when affi xing and setting up the sensors on the rotor blade, photos and other information on the installation can be documented in the app. This data is transmitted to the respective controller. Compatibility counts Thanks to open interfaces, the rotor blade detection modules from Phoenix Contact can also be integrated into existing controllers. Extensions with additional sensor technologies are also possible. The operator obtains clarity about the status of their system even faster if the modules are used together in a switchgear combination from Phoenix Contact, which also includes the innovative industrial PLCnext Technology controller. This evaluation unit including application software can communicate with the control room via Modbus/TCP and PROFINET remote control protocols. The sensors communicate over the 868 MHz frequency band. phoenixcontact.com/wind 21