Advanced Inspection Technology: Evolving Solar Energy

Clean energy development is moving forward globally at an increasing pace. Making clean energy more efficient is critical to its adoption and this is where large-volume precision measurement comes into play.

Laser-based portable metrology systems used in aircraft and automotive inspection are now used to assess solar collectors, wind turbines and Europe’s most advanced solar thermal projects.

Gemasolar, located in Seville, Spain, is the world’s first commercial plant using a central tower and surrounding heliostat array to feed a thermal storage system. The project was built by Torresol Energy, a joint venture of Spanish engineering firm Sener Group and Abu Dhabi-based Masdar. Mirror structures in the high-precision heliostats precisely reflect sunbeams toward the receiver located at the top of a 140 m high tower. Sener’s heliostat assembly subcontractor Moncobra SA uses frequency-modulated coherent laser radar technology (FM CLR) from Nikon Metrology Inc. to precisely position flat mirror panel arrays on the giant heliostats. Laser radar completes automatic, noncontact, gauge-free inspection of a single heliostat in a matter of minutes, allowing Moncobra to produce 22 heliostats daily. This is one of the many technology innovations Sener has introduced to maximize the output of its concentrated solar power (CSP) plant portfolio, supplying electricity in line with demand. 

As photovoltaics, CSP and other energy projects grow more competitive, inspection technologies need to contribute to production efficiencies while assuring critical quality targets. Courtesy of SENER.

Gemasolar is also the world’s first CSP plant to feature tower technology with a molten salts receiver. This thermal storage concept uses intense heat stored during the day to produce electricity at night. With thousands of 11×12m. heliostats targeting the sunlight receiver, the salt substances heat up and descend to the hot salts tank where they are stored at more than 500 °C. From here, the salts are transferred to heat exchangers, and subsequently to the turbine and electrical transformer before adding electricity to the net grid. Although the use of a tower surrounded by flat-mirror heliostats is less mature than parabolic trough technology (long parabolic mirrors), it potentially offers a higher energy yield. 

The Gemasolar heliostat array and thermal tower is located in Seville, Spain. Courtesy of Nikon Metrology Inc.

All heliostats are designed to exhibit a different slightly parabolic reflective shape, depending on the position of the heliostat in relation to the tower. Immediately following inspection, the measurement report is automatically saved on the network and sent to Sener for verification. The implemented control system decides whether the required curvature for each heliostat mirror array is achieved within specification. Based on mirror deviation values specified in the inspection report, assembly workers properly modify the orientation of the mirror panels. After tuning the mirrors, the laser radar performs a final inspection verification to confirm accuracy before turning out a new heliostat. 

Nikon Metrology Inc.'s MV351HS laser radar unit. Courtesy of Nikon Metrology Inc.

 A different laser tracker 

Laser trackers are nothing new. Similar in appearance, laser radar presents unique and significant differences. Laser trackers require an SMR (spherically mounted retroreflector) or other probing device that is held manually against the object being measured. By comparison, laser radar directs a focused laser beam to a point on the object being measured, while recapturing a tiny portion of the reflected light to determine absolute range to the measured point. Combined with horizontal and vertical laser beam angles, the 3D coordinates of the acquired points are determined in real time. 

This can increase productivity, as fewer procedures are required, making the entire process significantly faster. The system can even run unattended. 

Essentially, laser trackers are manual systems that track a probe, unlike the laser radar, which is a driven system. This means laser radar can be automated and, if needed, set up on multiaxis robots for an even higher degree of automation. Production can continue uninterrupted while ensuring high-quality metrology results. The technology is also particularly well-suited for large part volumes. With an effective radius of up to 50 m, a laser radar could be set up at the 50-yard line in a football game and hit both end zones with 3D uncertainty of less than 0.02 in. 

Nikon Metrology Inc.’s laser radar unit, mounted on a multiaxis robot. Courtesy of Nikon Metrology Inc.

Measuring solar panels 

As laser radar only requires a fraction of a percent of the reflected light to be returned and analyzed to determine measurement results, the technology is suited to handling highly reflective surfaces. In the fast-growing concentrated solar energy industry, such technology checks the geometric integrity of flat or parabolic mirrors and the understructure. Critical in this regard is its capability to accurately and efficiently trace faulty bending and misalignment. 

It takes roughly five minutes to measure a single heliostat in enhanced metrology mode. This is much shorter compared to a laser tracker system, and also much less cumbersome because the tracker requires a crane to precisely position a large gauge with spring-loaded targets on top of a heliostat’s reflective surface. With the laser radar, it is possible to avoid the complexity of taking measurements using laser trackers. Noncontact inspection performed in a fraction of the time has been the main driver for Sener to opt for the laser radar inspection system. 

A parabolic trough in Cádiz, Spain. Laser-based inspection ensures geometric integrity. Courtesy of Nikon Metrology Inc.

Valle 1 and Valle 2 are adjacent Masdar solar plants located in Cádiz, Spain, that feature parabolic trough solar technology combined with molten salt storage facilities. The two plants have a combined power capacity of 100 MW and are now fully operational. The footprint of the solar field covers 510,000 square meters, and the molten salt storage system allows for seven to eight hours of power generation without sunlight. These plants will produce approximately 330 GWh/year, which is equivalent to the average consumption of 40,000 households, or the entire city of Cádiz. Moreover, the plants displace more than 90,000 tons of CO2 a year. 

Both plants’ parabolic trough technology has unique mechanical characteristics, such as noticeably lower steel weight and fewer assembly hours compared to similar collectors. These advantages are significant, given that a conventional 50-MW solar plant uses 90,000 meters of parabolic trough mirrors requiring about 15,000 tons of steel. 

Measuring wind turbine blades 

Wind turbine blades are highly engineered components with many geometry-dependent features, including the pressure and suction sides of the blade and custom leading edge profiles. A recent wind turbine blade project encompassed surface inspection of a 45 m. blade that required completion in a single eight-hour period.

As photovoltaics, wind and other energy projects grow more competitive, inspection technologies need to contribute to production efficiencies while assuring critical quality targets. Courtesy of Nikon Metrology Inc.

The laser radar measured 48,000+ inspection locations with 25µm, single-point uncertainty in the requisite shift. By comparison, completing the same single shift inspection assignment using laser tracking technology would require at least three separate laser tracker systems and operators, as well as large overlay templates and additional tooling. 

Common sense checklist 

 In determining if laser radar is right for a given work or application, several common-sense business concerns must be addressed: 

• Accuracy. There’s no point in beating around the bush — what is the accuracy threshold you and your customers require now and in the foreseeable future? 

• Measuring volume. What parts demand measuring and inspection — micro parts or entire wind turbine blades, or in between? A long standoff scanner can also reach inaccessible or dangerous areas. 

• Portability. Do parts have to be measured on the factory floor, in-process, or delivered to a controlled-environment metrology department? Is a separate metrology lab and/or a production inspection solution required as parts are made? Will a portable solution bridge the gap, if needed? 

• Automation. The ability to automate and run the system unattended can result in lower manpower costs and is ideal for repetitive tasks. 

• Data-acquisition speed and software compatibility. The nonstop growth in computing power has made possible many advances in inspection. Is report data available in easily understood forms? Can reporting be completed offline, leaving articulated arms or CMMs dedicated to inspection tasks? Customer can choose between a series of metrology software solutions on a large scale or use software libraries to specify its own process of measurement. PolyWorks, Spatial Analyzer, Verisurf and Metrolog are those used most frequently in conjunction with Laser Radar.

• Cost. The noncontact and automated laser radar system can satisfy all of the following metrology aspects: 

    • Quality assurance applications, including part-to-CAD comparison, feature, and gap and flush inspection. 

    • Routine and event-driven inspections such as first-article inspections, incoming and outgoing inspections, and troubleshooting failure investigations. 

    • In-process applications, including component alignment and robotic positioning. 

    • Tool building and alignment, including locating and adjusting tool features in real time. 

    • Tool digitalization and documentation of as-built tools and die surfaces. 

    • Model digitalization such as scanning artistic models and performing design layups for in-process and outgoing quality assurance. 

    • Routine maintenance, including static and dynamic inspections of tooling assemblies. 

 As photovoltaics, wind and other energy projects grow more competitive with conventional generation, inspection technologies must contribute to production efficiencies while also ensuring critical quality targets. Laser radar, with its versatility and unique attributes, is a unique solution to this growing segment. 


Frequency-Modulated Coherent Laser Radar Technology (FM CLR), An Overview 

The major strength of laser radar is that it can scan complex geometry that is too complex, hard to reach or labor-intensive to evaluate using other methods. The system works indoors or out, in any lighting, and on any material or finished surface with a reflectivity of even less than 1 percent. Laser radar is capable of measuring both freeform surfaces and geometric features due to proprietary frequency-modulated laser technology. 

As the invisible eye-safe laser light travels to and from the target, it also travels through a reference path of calibrated optical fiber in an environmentally controlled module. Heterodyne detection of the return optical signal mixed coherently with the reference signal produces the most sensitive radar possible. The two paths are combined to determine the absolute range to the point, and the high-modulation bandwidth makes precise measurement possible in a millisecond. Combined with the measured horizontal and vertical laser beam angles, the 3D coordinates of the acquired point are determined in real time. As the measuring laser is invisible, the laser radar additionally emits a red laser pointer. Source: euroPHOTONICS

Solar PV Own-Consumption In Rural Areas

As widely reported, the solar photovoltaic energy penetration in Spain reached a cumulative installed PV capacity of 4,667 MW at the end of December 2015, according to the latest statistics released by Spanish grid operator Red Eléctrica de España (REE). 4,423 MW of this  capacity was installed in Spain’s mainland, while 78 MW and 166 MW were installed in the Balearic Islands and the Canary Islands, respectively.

The installed solar power represents 4.3 percent of the country’s total generation capacity. The country had 4,656 MW of installed PV capacity at the end of 2014. This means that in 2015 approximately 11 MW of PV systems were connected to the grid in Spain. In 2014, only 7 MW of new PV capacity was installed. Read the Renewables 2016 Global Status Report for more. Check out REN21’s Renewables Interactive Map for country specific data.

Courtesy: REN21

While from recognized instances it augurs that could become to the order of 30 percent. A big part of that future development will be based on the photovoltaic own-consumption, and one of the great hopes should focus on facilities in rural areas, as it can and should be an alternative to current systems of power generation and a significant improvement in energy efficiency.

2015 Renewable records worldwide:

The installed renewable capacity increased by 147 GW, but Spain shows a general stagnation in almost all sectors.

2015 was an "extraordinary" year for renewable energies worldwide, according to the latest report qualifies REN21 2016 GSR (Renewables 2016 Global Status Report). Total renewable power installed at the end of last year reached 1,849 GW. In this world stage, the EU has lost its leadership by reducing its investment in clean energy by 21% in 2015, returning to the levels of 2006. On Spain, the report highlights the gradual disappearance of our country from the PV world map.

First published in 2005, this report is the result of a collaborative work which involved some 500 authors. Its aim is to analyze the state of the markets of renewable energies and political trends and industry innovations.

According to the document REN21 association in 2015 renewable power across the globe increased by 147 GW, the highest figure to date. In many markets, clean energy have been placed as the main energy source. This rapid growth is due to several factors such as increased cost competitiveness of renewable sources compared to fossil fuels, favoring political initiatives for this sector, improving access to funding, greater concern for energy security and the environment or demand growth in emerging economies.

In late 2015, countries with the highest total installed renewable capacity are China, US, Brazil, Germany and Canada. In Europe, for the eighth consecutive year, renewables account for 77% of the capacity of energy production, but overall a downward trend in many Member States, due to declining investment.

Focusing on Spain, and specifically in the solar sector, the report regrets that after leading the market in 2008, the presence of our country in the photovoltaic map has been gradually disappearing due to the retroactive policy changes and rates for own consumption.

Another aspect that the report highlights of Spain is that just added new capacity to the installed renewable electricity capacity. In CSP technology, for example, it notes that during 2015 no recorded infrastructure construction or new projects for 2016 are expected.


As for solar energy, we note that this market fell by 6% in Spain, in line with the European scene, where only Denmark and Poland shed positive growth data. Among the reasons for this shrinking market at Community level, the report points out complicated bureaucratic procedures subsidy schemes, the decline in construction of new buildings and competition from other thermal technologies.

Opportunities that this system would bring to society are fundamentally creating mechanisms that undoubtedly:

• would cheapen the cost of energy in homes, businesses and industries subsistence users in rural areas
• would assurance to meet European commitments development of renewable (the now famous 20-20-20) and new objectives set out in cop21
• would reduce energy dependence on fossil fuels, with a better balance of the balance of payments
• would create a scenario of "energy democratization", which will result in the welfare of citizens.

Biomass technologies, Wind and Solar can cover nowadays the spectrum of energy consumption, although the photovoltaic seems to cover most of the power demand in the coming years.

The installation of photovoltaic own consumption is stronger, since small productive farms and rural residents are increasingly interested in installing on their properties electrical systems due to lower installation prices in recent years with costs below the €10 cents per kWh within the scope of a purchase agreement valid for a period of 25 years.

PV-Water Pumping Irrigation Systems:

This type of facility meets the new needs of irrigators to provide water for dry-lands in a much more economical way, because everything that involves improving the supply and dispose of water use for irrigation is a real progress for these farmers and also for all regions.

There are vast amounts of land which could facilitate the use of irrigated cultivated lands, by no means of arable land irrigated. Therefore the chances that pumping would be endless arable dry-lands.

Photovoltaic solar energy in rural areas contributes to the fight against climate change:

The commitment to photovoltaic solar energy in rural areas as a means of combating climate change and active policies to fight in this area provide an opportunity for the future development of rural areas, since in this respect the commitment renewable energy can stimulate economic diversification and creation of new jobs, improving the management of agricultural land, increasing the efficiency of agricultural machinery, giving economic output and agricultural products through energy recovery.

Therefore, the photovoltaic solar energy installations are a good solution for isolated network facilities where they have to produce their own electricity, in many cases with diesel generators.

Development Actions for Rural Own-Consumption:

Although solar PV is well known, in addition to the significant damage that is causing the application of tolls on self-consumption, there are a number of prejudices, like the remaining tariff deficit, widespread in the past, that have a bad image to the sector, requiring the performing a series of actions for its normal development:

• Disseminate this technology among farmers to understand that solar energy photovoltaic solves many problems of its energy and electricity needs.
• To encourage more professionals photovoltaic solar energy, to spread the great opportunity it posed to rural areas, offering their services to farmers and rural dwellers.
• Itemize the different cost-effective solutions for photovoltaic solar energy in rural areas, both connected to the network, as well as off-grid facilities.
• Promoting innovation in autonomous or connected photovoltaic solar power grid, involving autonomous administrations and local authorities.

Hopefully the addition of all these actions in the future government will perform the necessary changes in the sector, so that solar PV will continue to be a vector for growth as SolarPower CEO James Watson said «In the current post-feed-in tariff climate, we must make sure we have the right electricity market design and the right long-term investment signals for solar to flourish. We hope that the European Commission’s forthcoming market design reform and Renewable Energy Directive will pave the way for the 200 GW benchmark,»

EGA is registered as 14.302 engineer at COITIM

"Earthing Systems In High Voltage Facilities" By Industrial Engineer PhDr Jorge Moreno Mohíno

Design, Calculation and Verification of Grounding Systems of High Voltage Facilities is meeting all the requirements of High Voltage Power Electric Lines Regulation (RLAT) published in June 2014. By the detail of its contents, its many theoretical examples and practical guidance applied to this utilities verification is one of the ones of those authors who keep all regulations details up to date.

The book is an enhancement of  the 1st HV Power Lines Regulation: published years ago.

The book is divided into seven chapters highlighting the third chapter where the way to get the fault currents to ground and grounding currents are distinguished, also the current distribution by the various grounding systems when they are interconnected through underground cables is also shown, facilitating the implementation of projects of ground facilities in urban environments, without resorting to unnecessary oversizing arising from incorrect approaches. Also it stands out for its novelty the seventh chapter verification systems earthing (measurement of soil resistivity, measuring grounding resistance and measuring step voltages or touch voltages), which will be of great help for technicians and authorized control organisms (OCAS) during inspections or verification of high voltage installations facilities.

The text is supplemented by an annex to the characteristics of many type of electrodes, different configurations and at different burial depths, far surpassing the old text of UNESA method that included reference tables.

CONTENT

    1. Physical Fundamentals of grounding systems.
    2. Characterization of the grounding electrodes.
    3. Calculation of ground currents.
    4. Requirements for the design of grounding.
    5. Draft a facility grounding.
    6. Application Examples.
    7. measures grounded in high voltage installations.
    Annex I. Calculation sequence impedances.
    Annex II. Characteristic parameters of type configurations calculated using the Load Simulation Method (LSM)

After a thorough investigation and written by Industrial Engineering Doctor Jorge Moreno Mohíno and his collaborators, the book has recently seen the light "Earthing Systems in High Voltage Utilities. Design Calculation and Verification ", An excelllent work that fills an important gap in line with the current documentary legal regulations, which actually did not cover the needs of different professionals. So far, they should be referred to document UNESA "Method of calculation and installation project ground to processing centers connected to networks of third category," published in 1989 and generally used for the calculation and design start grounding of high voltage electrical installations.

The new book has been published with the push of Iberdrola Electricity Diistribution and the FFII (F²I²) "Foundation for the Promotion of Industrial Innovation", along with the investigations carried out and results obtained within the "Tabón" project, an initiative of R&D financed by the mechanism of the European Economic Area (EEA-Grants) with financial contribution of Iberdrola SA, Iberdrola Electrical Distribution and ATISAE.

Born in Yepes (Toledo), Spain, PhDr. Moreno holds a degree in Industrial Engineering from the Polytechnic University of Madrid (UPM) in 1989, and PhDr in Industrial Engineering in 1995.

With solid experience in university education field, between 1989 and 1995 as a professor in the Electrical Engineering Department at the UPM. Since 1995, he assumed the Palacios Bregel Laboratory of Magnetic Measurements UPM University CEO responsibility. He is also expert project evaluator for the Accreditation Agency for Research, Development and Technological Innovation (Aidit). His research interests include magnetic measurements and analysis of earth fault systems.

The significance of the publication is given by the importance of safety in the field of high voltage deployments commissioning systems. In fact, one of the risks of the electricity distribution activity are earth faults produced, among other reasons, due to the aging of insulating materials, unexpected breakdowns, or any other incidences. It is in these circumstances that the correct design, implementation and verification of grounding systems provides a guarantee of safety for both people (workers, users and passersby or third parties) to the facilities themselves.

As noted above, to date there was no text to gather updated theoretical and practical aspects, such as distinguishing between ground default current and rounding current In this book the current distribution by the several grounding systems is also treated with great practical sense when they are interconnected through screens underground cables, which will undoubtedly facilitate the implementation of projects of facilities commissioning ground in an urban environment, without resorting to unnecessary derivatives oversizing of an incorrect approach.

The book is particularly aimed towards engineering and senior cycle students, designers, engineers, professionals, installers and energy distribution companies. All they will have a suitable tool that fits Regulations Power Lines High Voltage (RLAT), published in March 2008 and Regulation of Electrical Installations High Voltage, later updated on June 2014, which have led to major changes for the design, calculation and verification of earthing in high voltage electrical facilities.


Seven chapters and two annexes

Jorge Moreno and his colleagues have structured their work in seven chapters and two appendices. In the first one the physical foundations of the grounding system, delving into the theoretical aspects required to understand obtaining parameters that characterize the different types of electrodes are described, as well as the methods used in practice for obtaining these parameters (method Howe and the Load Simulation Method LSM).

 The following method applies Howe as the LSM method for obtaining the characteristic parameters of the electrodes, making a comparison between them and the existing commercial software.

The third chapter details the calculation methodology for solving the fault currents and ground by the electrodes, specifying the calculation for different earth network configurations (isolated neutral, impedance, etc.) as well as for different high voltage installations (support cable airline without ground wire, transformers and substations).

Meanwhile, the fourth includes regulatory requirements for the design of the grounding, its constitution, safety requirements, sizing and shows some of the electrodes commonly used by Iberdrola Electricity Distribution in its high voltage facilities.

In the fifth chapter describes the procedure used to project a grounding installation, first by investigating the terrain, the determination of the maximum off earth currents and leakage time of the defect current and the preliminary design for a detailed installation. It also describes the calculations of system resistance grounding, the step voltage and touch voltage that occurred in the system, the step voltage and touch voltage that are supported in the installation and its comparison with previous and obtained voltages outside transferable.

As for the sixth chapter, it presents seven fully solved examples, which serve as much help to the designers of such facilities. Notably design grounding of transformer type "Lonja" where obtaining current grounding is a determinant to meet regulatory requirements factor. the design of the ground support airline ground wire without ground wire, transformer fed from a network with impedance neutral, isolated neutral, isolated neutral with excess ballast and ends with the contemplated design grounding of a substation.

It is noteworthy in this context the design example grounding of a transformer belonging to a distribution network with isolated neutral endowed with an internal ballast zig-zag, at the head of substation, typical of the distribution network medium voltage used in the Canary Islands.  In this method actual ground currents that occur in the processing center are determined, justifying why the use of simpler electrode (buried conductor stakeless) without oversizing the grounding installation.

The seventh chapter is entitled "Measurement of earthing in high voltage installations" and is intended for professionals who will carry out the checks and inspections on the premises grounding (accredited professionals, official institutions, installers, HV installers and energy distribution companies).

 As its author states, in this chapter it places special emphasis on safety precautions to take into account not only during the measurements grounding the high voltage but also in pre-measures operations and during procedures for execution. With special editorial care, the book illustrates didactically each example:

 #1.- The soil resistivity measurement

#2.-  Also, the different methods used for measuring the resistance of the grounding system, depending on the type of installation (airline support without ground wire and ground wire, transformers and substations) are specified.

#3.- As well as measurements to be considered in the case of touch voltages and step voltages.

Towards the end of the work, the author has reserved us as an annex, a section that includes the calculation of sequence impedances of both airlines without ground wire with a ground wire and two ground wires as underground lines with grounded at one end, at both ends and Cross-Bonding screens. These impedances are necessary to establish the calculations of ground fault currents in different HV facilities, calculations referred to in the third chapter.

Finally, the second annex includes numerous parameters electrode configurations, which will greatly assist the project and design of earthing in high voltage installations. These parameters were calculated by the method of simulated loads (L.S.M).

 - Please feel free to buy it here online in Spanish See more at: www.canariascnnews.com