Hur varmt är det i tanken? Vilket tryck ger pumpen? Det är två exempel på frågor som kan besvaras med processmätteknik.Att mäta är att veta, sägs det, men det gäller ocksåatt veta hur bra man mäter! Felaktiga mätresultat skaparproblem, osäkerhet och kan rent av vara farliga.I den här boken får du hjälp att undvika mätfel, du fårlära dig om olika mätprinciper och hur mätare av olika slagbäst används och monteras. Främst handlar det om temperatur,tryck, flöde och nivå men även annat som finns i enprocessindustri. Du får kunskap om kalibrering, spårbarhetoch mätosäkerhet, och samtidigt om saker runt omkringmätinstrumenten, till exempel CE-märkning, elstörningar,explosionsskydd, skrivregler, signalöverföring, standardermed mera

Innehållsförteckning:  1: Mätteknik 2: Lästips – Gör så här 3: Mått i historien 4: CE-märkning 5: SI-systemet 6 :Signalöverföring 7: Säkerhet 8: Mätosäkerhet A 9: Fysik och matematik 10: Mättekniska begrepp 11: Temperaturmätning 12: Tryckmätning 13: Flödesmätning 14:Nivåmätning 15: Värmemätning 16: Vakter och larm 17:Serviceinstrument 18:Konduktivitetsmätning 19: pH-mätning 20: Densitetsmätning 21: Vägning 22: Fuktmätning 23: Mätosäkerhet B 24: Kalibrering 25: Pumpar och ventiler 26: Rörledningar 27: Mätosäkerhet C 28: Tabeller 29:Index

The Reference Step Method for calibrators can be modified for calibration also of the gain ratios on a meter. The method has earlier been evaluated in the range 100 mV-1000 V on DMM HP 3458A1 and shows that an accuracy of typically < ± 0.2 μ V/V could be obtained. We have investigated the performance of the method when calibrating ratios in the range 1 mV-100 mV on two common nV-meters. In our comparisons with the Josephson Voltage Standard the differences are within ± ± 12μ V/V at the ratio 10m V:1mV and within ± ± 1.3μ V/V at 100mV:10mV.

Biogas is a renewable energy source with many different production pathways and numerous excellent opportunities for use; for example, as vehicle fuel after upgrading (biomethane). Reliable analytical methodologies for assessing the quality of the gas are critical for ensuring that the gas can be used technically and safely. An essential part of any procedure aimed at determining the quality is the sampling and transfer to the laboratory. Sampling bags and sorbent tubes are widely used for collecting biogas. In this study, we have combined these two methods, i.e., sampling in a gas bag before subsequent sampling onto tubes in order to demonstrate that this alternative can help eliminate the disadvantages associated with the two methods whilst combining their advantages; with expected longer storage stability as well as easier sampling and transport. The results of the study show that two parameters need to be taken into account when transferring gas from a bag on to an adsorbent; the water content of the gas and the flow rate used during transfer of the gas on to the adsorbent. © 2019 by the authors.

Liquefied Natural Gas (LNG) and Liquefied Biogas (LBG) utilization within the heavy duty transport sector is today a sustainable alternative to the use of oil. However, in spite of the high degree of insulation in the storage tank walls, it is impossible to fully avoid any net heat input from the surroundings. Due to some degree of vaporization this results in variation in gas composition during storage at refuelling stations, potentially leading to engine failures. Within this study, a vaporizer/sampler has been built and tested at a station delivering liquefied biomethane (LBG) and occasionally; such in this case, LNG to heavy and medium duty trucks. The vaporizer/sampler has then been used to study the variation of the LNG composition in the storage tank during a two weeks period. The results clearly underline a correlation between the gas phase and the liquid phase as the concentration changes follow the same trend in both phases. Two opposite effects are assumed to influence the concentration of methane, ethane and propane in the liquid and in the gas phase. On one hand, because of the probable presence of not fully mixed layers in the storage tank and due to vehicles being refuelled, both liquid and gas phases are enriched in methane at the expense of ethane and propane. On the other hand, due to boil-off effect towards the end of the storage period, both liquid and gas phases are enriched in ethane and propane at the expense of methane.

An absolute determination of the ratio of a 100 kV DC divider has been made. A new Zener device that has recently become available has been used in a step-up mode to obtain the divider ratio. The uncertainty of the determination is 5.5 ppm.

Modern dielectrics used in power capacitors can exhibit a dissipation factor lower than 0.005 %, which approaches the limits of presently available measurement techniques. This article reviews techniques, apparatus, and available calibration services for dissipation factor with regard to lowest achievable uncertainties. It is shown that further metrological advances are necessary to lower uncertainty in the measurement to levels at least five times less than presently achievable, in order to ensure traceable and quality-assured measurement of modern dielectrics with such low dissipation factors

Very Low Frequency (VLF) tests are often used for after-laying tests of power cables since the reactive power demand is much lower at VLF than at 50 Hz. In order to augment the usefulness of the test, it is often complemented by a measurement of dielectric dissipation factor (tan ), where the acceptance of the tested object is based on this measurement. A traceability chain for dissipation factor at high voltage and very low frequency has as yet not been recognized by the International Bureau of Weights and Measures (BIPM), which results in difficulties to prove the quality of the measurement. The measurement is complicated by the limited range of the current in the test object that can be resolved by available high voltage test equipment, thus limiting the possible choices of reference systems. A novel reference measuring system that can fulfil these needs has been developed at SP Technical Research Institute of Sweden in the capacity as National Measurement Institute. The traceability of the system to National Standards of Measurement is ensured by careful scientific work and analyses. This measuring system has the ability to measure dissipation factor at 0.1 Hz in the voltage range from 0.5 kV up to 50 kV with an uncertainty better than 0.004 %.

High voltage equipment will be subjected to several types of electrical stress during operation. A battery of factory tests is defined to ensure that the equipment will perform satisfactorily in service. One of the crucial tests is to apply a simulated lighting impulse as standardised to a double-exponential impulse with at front time of 1.2 µs (± 30 %) and a time to half value of 50 µs (± 20 %). Although this wave-shape only approximates natural lightning, there is a solid body of experience within industry, proving that reliability of equipment in service is adequately proven by the standard waveform. It is however crucial for consistency of results that the both voltage level and wave-shape are correctly measured. This paper discusses the requirements and performance of the recording instruments used, leaving the properties of high voltage impulse dividers outside the discussion. The requirements for the recording instrument – transient recorder – are given in IEC 61083-1. The standard provides requirements for, and/or tests to verify, that the recorder has moderately fast response, fast settling time, high resolution, linearity under dynamic conditions, high accuracy and reasonably low internal noise. This is partly in contrast to major trends in transient recorder development, where fast sampling and fast step response are prioritized ahead of high accuracy and fast settling without creeping response. We have therefore evaluated several commercially available recorders in order to find one with respectively flat and reasonably fast step response. In this campaign, a proprietary step generator based on the use of a mercury reed relay has been used. Evaluation of this device is submitted to ISH 2017. It has been found that the measured flatness of the step response directly after the step is a good first indicator of the performance of the transient recorder. This is identified in IEC 61083-1 clauses 1.5.2 and 1.5.3, as a requirement on stability of the recorded step from 0.5 T1min to T2max. For lightning impulse this means from 0.42 µs to 60 µs. For approved transient recorders the requirement is to be within 1 %. For reference transient recorders, a limit of not more than 0.5 % should be applied. Further proof of the accuracy of the transient recorder can be achieved by convolution of an ideal waveform with the recorded step response and analysing the resulting curve with lightning impulse parameter software. A third possibility is to make direct calibration of the transient recorder, using a calculable impulse calibrator. Several state-of-art transient recorders have been evaluated and the results show that only a few are suited for measurement of lightning impulse. Also, the variation of the performance between the ranges and channels of one instruments are significantly large. Both direct assessment of step response as well as result of convolution with a theoretical 0.84/50 µs impulse will be reported. The agreement with results obtained with a calculable impulse calibrator will be illustrated.

An effort is pursued by several European National Measurement Institutes to lower the uncertainties in calibration of UHV measuring systems for lighting impulse. To this end, several reference dividers are investigated as regards their accuracy both for amplitude and for time parameters. At SP - RISE Research Institutes of Sweden, a 500 kV resistive reference divider has been in use since 2000. Additionally an 800 kV resistive divider is investigated as a possible reference divider for UHV lightning impulse measuring systems. The best uncertainty for the 500 kV reference measuring system is 1 % for voltage amplitude and 3 % for time parameters. The present work aims at lowering these uncertainties by means of better characterisation and evaluation of the possibilities to apply corrections for known errors. The scale factor and dynamic behaviour of a resistive divider can be conveniently determined at low voltage and frequency. Further experiments such as linearity tests and augmented by scientific work is needed to ascertain the performance at high voltage. Step response plays a major role in the characterisation of dividers, and in this work much effort has gone into gathering step responses and evaluating them for various circuit layouts to characterise the variation of the step response due to circuit dimensions and diverse proximity effects. The step applied to the divider is generated by a mercury wetted relay based step generator with an output voltage of 200 V. The step rise-time is a few ns, and thus appreciably faster than the response of the divider. Apart from inspection of the step response itself, evaluation of measurement errors is performed by convolving an ideal curve with the step response of the divider, including its transmission cable. The convolved signal is evaluated with impulse evaluation software and the parameters compared to the ideal input. The difference is a measure of the errors introduced by the divider. This procedure follows IEC 60060-2: 2010.

Lighting impulse measurements are made as a matter of routine in high voltage testing of high-voltage electrical equipment. The test is often decisive for acceptance of the equipment under test, and consequently proper and precise calibration of the measuring system is needed. The present work centres on the need to quantify the errors of reference measuring systems for lightning impulse. Scale factor determination at low frequency (or DC) is the starting point for this determination. The extrapolation from this frequency domain to the domain where microsecond pulses must be faithfully captured requires application either of methods in the frequency domain or in the time domain. Radio frequency measurements are only well defined for coaxial structures and at impedances in the range of 50 O or thereabouts, making them difficult to apply to the large structures of high-voltage measuring systems. The converse method in the time domain is to apply a Dirac impulse to the system and calculate the response to an assumed input signal by convolution. A true Dirac pulse is not readily available and in practice the applied pulse is a step voltage, which is then derived with respect to time and convolved with the applied signal to obtain the response of the measuring system. The step generator used for this purpose should have very fast front without oscillations. The intent is to achieve a close approximation of an ideal step function, which when derived with respect to time, yields the impulse response of a tested system. A necessary prerequisite is that the step is much steeper than the lightning impulse, and is flat after the step on times much longer than the impulse. The ideal switch element in such a step generator should have infinite resistance and zero capacitance in the off-state, very fast switching to on-state and very low resistance in on-state. The mercury wetted reed switch has often been used for this purpose since it has good characteristics in all these respects. Few, if any, electronic components exhibit competitive advantages compared to the reed switch. The relative lack of parasitic effects means that it is close to being an ideal device. Based on earlier experiences by the authors, a new design has been developed with focus on electrical screening and coaxial design in order to realise a step generator that works into a high impedance instrument. Considerable work has been performed to characterise the new device with regard to steepness of step and most importantly, to voltage stability after the step. The most demanding part of this work has been to separate the performance of the switch from that of the oscilloscope. Findings indicate that the step rise-time is less than 0.5 ns, and settling to within 0.5 % within 10 ns.

An effort is pursued by several European National Measurement Institutes to lower the uncertainties in calibration of UHV measuring systems for lightning impulse. To this end, several reference dividers are investigated as regards their accuracy both for amplitude and for time parameters. During these investigations a deterioration of step response was identified when longer coaxial cables were inserted in the measuring circuit. The measured front time T1 was also affected, in one observed case by 2.5 % elongation of front time as another 25 m cable was inserted. Compared to the intention to calibrate front time measurement to better than 5 % uncertainty for front time, this contribution must be well known, or preferably be eliminated. This paper presents the experimental findings from these investigations. The investigated cables included selected coaxial, tri-axial, and cables with a corrugated screen. The effect of cable length was also studied. The influence was first discovered when applying a very fast step (rise-time < 4 ns) to the high voltage arm of a resistive divider and convolution of this step with the time derivative of an ideal lightning impulse with 0.84/60 µs impulse. The calculated output was analysed with IEC 61083 compliant software to evaluate the front time. Subsequently, these analyses have been augmented by additional comparative measurements where two reference dividers were connected to the same impulse generator, and varying the cable length of one of them. The summarized changes in front time calculated for different combinations of cable and impulse voltage dividers are shown and discussed. It is noted that a change in T1 error depends both on length of cable and its type. The results show that non-negligible front time errors may be introduced when the cable length is increased. To support these findings, further tests have been carried out with two reference impulse dividers connected in standard calibration configuration in accordance with IEC 60060-2. One divider was used as reference, while the cable for the other was varied. In this way, the change of error between configurations could be measured. A theoretical study has also been performed, calculating the distortion of a lightning impulse on a coaxial cable. The results agree qualitatively with experiments, but the detailed results show discrepancies that need further investigation.

Losses of HVDC converter stations need to be accurately quantified to support evaluation of bids for such systems and to underpin efforts to reduce greenhouse gas emissions. At present, these losses are estimated, based on loss calculations for individual converter components, and no reliable method exists to measure the actual HVDC converter station loss as difference between power on the AC- and DC-side of the station. The necessary requirements for such a measurement are investigated in this study, and a tentative design of a suitable loss measuring setup is explored. This approach is a useful alternative for those cases where a direct measurement of losses via a temporary connection with two converters operating in back-to-back mode cannot be made.

We report the first precision QHR measurements at SP using a graphene chip. We compare the results of a resistance calibration using GaAs based chips with the results using a graphene chip. The results agree within a few parts in 10⁹ for calibrations of 100 Ω and 10 kΩ resistors. Consistency checks indicate that the uncertainty is lower with the graphene chip, and the noise level is slightly lower. The measurements with the graphene chip were performed exclusively at 4.2 K, which simplifies the calibration procedure considerably compared with GaAs chips.

This article presents a method for realising absolute phase and ac resistance for current shunts using only impedance ratio measurements. The method is based on three geometrically identical current shunts with different resistances, but with the same inductance, capacitance and ac resistance (change of resistance at ac compared to dc), We demonstrate how the inductance, capacitance and ac resistance can be calculated from the complex impedance ratio measurements, thereby realising absolute current shunt impedance. This method simplifies the procedure of current shunt calibration, since the same impedance ratio setup which is used to compare a shunt to a reference shunt, is used to realise the impedance of the starting reference shunt.

This paper presents a simplified method for realizing absolute phase and ac resistance for current shunts using only impedance ratio measurements. The method is based on three geometrically identical current shunts with different resistances, but with the same inductance, capacitance, and ac-dc resistance change of resistance at ac compared to dc). We demonstrate how the inductance, capacitance, and ac resistance can be calculated from the complex impedance ratio measurements, therefore realizing absolute current shunt impedance. The method gives competitive uncertainties of around 200 μΩ/Ω for amplitude and 400 μrad for phase at 1 MHz in the 1-Ω range.

We have measured the geometric deformations of the Onsala 20 m VLBI telescope utilizing a combination of laser scanner, laser tracker, and electronic distance meters. The data put geometric constraints on the electromagnetic raypath variations inside the telescope. The results show that the propagated distance of the electromagnetic signal inside the telescope differs from the telescope’s focal length variation, and that the deformations alias as a vertical or tropospheric component. We find that for geodetic purposes, structural deformations of the telescope are more important than optic properties, and that for geodetic modelling the variations in raypath centroid rather than focal length should be used. All variations that have been identified as significant in previous studies can be quantified. We derived coefficients to model the gravitational deformation effect on the path length and provide uncertainty intervals for this model. The path length variation due to gravitational deformation of the Onsala 20 m telescope is in the range of 7–11 mm, comparing elevation 0$$^{\circ }$$∘and 90$$^{\circ }$$∘, and can be modelled with an uncertainty of 0.3 mm.

The objective of the International Earth Rotation and Reference Systems Service (IERS) Working Group on Site Survey and Co-location is to improve local measurements at space geodesy sites. We appointed dedicated Points of Contact (POC) with the four different services of IERS as well as the NASA Space Geodesy Project in order to improve the efficiency of internal communication within the working group. Following the REFAG2014 conference, the POCs agreed on a common and general terminology on local ties that clarifies the communication regarding site surveying and co-location issues between and within the IERS services. We give brief introductions to the different observation techniques and mention some contemporary issues related to site surveying and co-location.

Nuvarande belysningsstandarder baseras enbart på tekniska krav, såsom ljusstyrka, jämnhet och luminans. Att även inkludera upplevelsebaserade krav skulle troligen främja bättre ljuskomfort, men även mer energieffektiva ljusmiljöer och produkter. Kunskapen om hur upplevda belysningsparametrar kan beskrivas är dock begränsad. Detta hämmar fastighetsägare och brukare att precisera önskvärda ljusmiljöer, liksom belysningstillverkare att utveckla produkter för nya marknader och tillämpningar. Syftet med detta forskningsprojekt var att utveckla och tillämpa sensoriska metoder på belysning. Till skillnad från tidigare metoder möjliggör sensoriska metoder objektiva bedömningar av upplevda belysningsparametrar.

En analytisk panel bestående av åtta personer som uppfyller särskilda urvalskriterier rekryterades och tränades att bedöma belysningsprodukter i ett multisensoriskt laboratorium på SP Sveriges Tekniska Forskningsinstitut i Borås. Metodutvecklingen fokuserade särskilt på en effektiv träningsprocedur, hantering av ögats adaption, samt bedömning av färg och skuggningar. Förutom laboratorie-försök undersöktes möjligheten att genomföra analytiska bedömningar i en verklig kontext med samma försöksuppställning och panel.

Resultaten visar att det är möjligt att använda sensorisk metodik för att genomföra objektiva belysningsbedömningar av armaturer; paneldeltagarna kunde skilja mellan attribut och prover. Signifikanta skillnader identifierades mellan de olika armaturerna, både i form av sensoriska och fysikaliska egenskaper såsom läsbarhet och bländning. Fysikaliska och sensoriska parametrar samvarierar dock inte alltid, vilket visar att fysikaliska och sensoriska mätningar ger kompletterande information om belysningskvalitet. Vidare visade bedömningsförsök i en verklig kontext att samma resultat uppnåddes som i laboratoriet, men med lägre signifikans, vilket verifierar metodens tillämpbarhet på belysning.

Den genererade kunskapen väntas på sikt bidra till utveckling av verktyg som stödjer kommunikationen mellan olika professioner inom ljusdesign och planering och på så vis främja mer önskvärda och energieffektiva ljusmiljöer.

The liberalization of electricity markets and the transformation of electric power systems to include large amounts of variable output generation, has led to a growing interest in flexible demand and demand response. Making demand response available on the wholesale market on a large scale is a challenge. Retailers and aggregators, providing services to individual consumers as well as bringing aggregated flexibility to the wholesale market, is foreseen to play important roles in this respect. This paper presents a aggregator decision support model for demand scheduling, including demand response and purchase bid optimization for day-ahead markets. Income from providing electricity to consumers, and costs related to imbalances, rescheduling and energy not served are also considered. The model includes risk management by applying the conditional value-at-risk risk measure. The feasibility of the developed model is validated through a case study using historical data from the Swedish power system and market.

The transition of the electric power system to reach sustainability goals leads to new market conditions with larger uncertainties. This constitutes new challenges and opportunities for new as well as for existing market players such as retailers. In a future more volatile and unpredictable market, financial risk management becomes an important element for such actors in order to achieve viable businesses. Different instruments can be applied for this purpose, where demand response can contribute in the short-term to manage risks related to price variations and imbalance costs. This study contributes to the enhancement of retailer's businesses by presenting a stochastic optimisation model exploring the possibility to apply demand response to control financial risk exposure. The model considers trading and demand response scheduling for different customer clusters, generating optimal trading volumes for day-ahead markets while also considering the possibility to trade intra-day. The optimisation considers uncertainties in prices and loads as well as imbalance settlement costs. Risk management is integrated into the model by applying conditional value-at-risk as risk measures. The developed model has also been applied in a case study with data from the Swedish and Nordic electricity market together with simulated load profiles for different customer clusters. 

Valid and precise quantification of clinical variables is essential for appropriate interpretation to inform healthcare decision making. The outcomes produced from different measurement procedures and instruments, purporting to quantify the same measurand, should be directly comparable. This ensures the appropriate application and widespread adoption of clinical research findings. Metrology provides a framework for the development of a common language of reference measurement systems, which have the potential to improve the accuracy and comparability of patients’ results. However, the practices, procedures and instruments used in social measurement are currently excluded from any formal metrological framework. In this paper, we build on previous arguments, and propose a new international body to bring together metrology, psychometrics, philosophy, and clinical management to support the global comparability and equivalence of measurement results in patient centred outcome measurement to improve healthcare.

Patient centered outcomes pertain to a patient's beliefs, opinions and needs in conjunction with a clinician's medical expertise and assessment. The rise of patient-centered outcome (PCO) measurement parallels increased interest in patient-centered care. PCO measures offer the opportunity for more meaningful measurement of health outcomes informative enough to guide treatment decisions. However, it has been suggested that, for practical and scientific reasons, existing PCO measures are currently not capable of delivering the kind of quality assured measurement required for high-stakes decision making. Potential solutions include: addressing the lack of units in PCO measurement through recourse to mathematical models devised to define meaningful, invariant, and additive units of measurement with known uncertainties; establishing coordinated international networks of key stakeholders guided by five principles (i.e., collaboration, alignment, integration, innovation and communication); better use of technology leveraging measurement through item banks linking PCO reports via common items, common patients, or specification equations based in strong explanatory theory. And finally ensuring PCO measurement always is associated with: (1) a clear definition of the measurand in regards to the intended clinical use; (2) a clear definition of the clinically allowable error of measurement; (3) international cooperation and consensus to navigate the complexities of the development of metrologically sound reference measurement systems; and (4) continued clinical validation of newly calibrated measures. In this article, we illustrate the principles to improve PCO measures with examples from breast cancer, vision-related patient-reported outcome measures, and dementia clinician-reported and performance outcome measures.

I dag finns tekniska belysningsstandarder som inkluderar parameterar så som ljusstyrka, jämnhet och luminans. Det som saknas är krav som grundar sig på människors upplevelser av belysning och ljusmiljöer. Att få med den upplevelsebaserade dimensionen skulle betyda ett helhetstänk som förmodligen skulle gynna både ljuskomforten och än mer energieffektiva ljusmiljöer och produkter. Att beskriva upplevda belysningsparametrar har hittills visat sig inte vara helt enkelt, och här saknas både kunskap och en gemensam begreppsvärld inom branschen; något som hämmar fastighetsägare att ställa lämpliga krav vid en upphandling liksom belysningstillverkare att utveckla produkter för nya marknader och tillämpningar. Det övergripande syftet med detta forskningsprojekt är att utveckla och tillämpa sensoriska metoder på belysning. Till skillnad från tidigare metoder möjliggör sensoriska metoder objektiva bedömningar av upplevda belysningsparametrar. Syftet med försöken som redovisas i denna delrapport är att vidareutveckla och testa metoden ytterligare. Detta görs genom att nya armaturer testas liksom att försök utförs i en ny verklig kontext (kontorsmiljö). Försöken bygger vidare på resultat från tidigare försök som har rapporterats om i (Boork et al, 2017).

En analytisk panel bestående av åtta personer, som uppfyllde särskilda urvalskriterier, har tidigare rekryterats och dessa personer tränades nu för detta specifika delprojekt för att bedöma belysningsprodukter i ett multisensoriskt laboratorium på RISE Research Institutes of Sweden i Borås. Metodutvecklingen fokuserade särskilt på en effektiv träningsprocedur, hantering av ögats adaption, samt bedömning av färg och skuggningar. Förutom laboratorieförsök undersöktes möjligheten att genomföra analytiska bedömningar i en verklig kontext med samma försöksuppställning och panel.

Resultaten visade att det är möjligt att använda sensorisk metodik för att genomföra objektiva belysningsbedömningar även för de testade belysningsprodukterna, dvs mindre LED-spotlights. Signifikanta skillnader identifierades mellan de olika armaturerna och som i tidigare försök spelade färgtemperaturen en stor roll för flera av de bedömda egenskaperna; inte minst förstås för ljuskällans gulhet och för läsbarhet (textkontrasten). Liksom i tidigare försök fanns det samband mellan de fysikaliska mätningarna och sensoriska bedömningarna, men inte för alla egenskaper, vilket visar att fysikaliska och sensoriska mätningar ger kompletterande information om belysning.  Vidare visade bedömningsförsök i en verklig kontext att likvärdiga resultat uppnåddes som i laboratoriet, om ändock något spretigare och inte heller lika entydiga i jämförelse med verklig kontext i tidigare försök.

Den genererade kunskapen väntas på sikt bidra till utveckling av verktyg som stödjer kommunikationen mellan olika professioner inom ljusdesign och planering och på så vis främja mer önskvärda och energieffektiva ljusmiljöer.

A large hydrogen infrastructure is currently in development across Europe. However, the industry faces the dilemma that they are required to meet certain measurement requirements set by European legislation that cannot currently be followed due to the lack of available methods and standards. The EMPIR Metrology for Hydrogen Vehicles project will be the first large scale project of its kind that will tackle the four measurement challenges that currently prevent the industry from meeting requirements set by International Standards such as flow metering, quality control, quality assurance and sampling. This paper presents a brief overview of the specific objectives of the project and focuses on the flow metering work package and the presentation of its planned tasks, which comprise laboratory and measurements in the field. Laboratory work will assess the use of substitute fluids to hydrogen to provide a safer and more cost effective method for the type approval of Hydrogen Refuelling Stations (HRS). To be able to link laboratory work to field testing, mobile primary standards will be developed and the design of a field testing primary standard will be addressed. The aim is to inform what the European national metrology institutes are currently developing in the field of hydrogen flow metering and quality control of HRS.

Traceability of the current ratio is crucial for the measurement of electrical energy in revenue metering. A comparison of the AC current ratio was therefore performed within EURAMET in the time period 2012-2016, using a precision CT as the traveling device. The Czech Metrology Institute (CMI) as coordinator processed the measurement results of the 15 European participating laboratories. The comparison of the results for transformer ratios of (4, 5, 6, 8, 10) kA 5 A at 15 VA burden and (4 and 10) kA 5 A ratios at 5 VA burden indicates good agreement between the participating laboratories. The main differences are found for phase displacement, at least in part due to instability of the traveling standard. .

A variety of commerce needs or requires accurate time, such as air traffic control, bank transactions and computer log file comparisons. Whenever the used time needs to be compared with a timestamp generated by another system, both systems must be traceable to a common reference, such as a local UTC(k) realization. Within this paper a distributed timescale using five nodes across Sweden is presented. The foundation for time keeping at each node is two cesium clocks, which are connected to time analysis equipment and equipment for producing redundant timescales. Both timescales are used and distributed throughout the time node and then prioritized by the local NTP servers, PTP grand masters, and other time distribution services. The timescales are monitored by RISE Research Institute of Sweden to ensure traceability to UTC(SP).To compare the timescales of each location with the other locations, GNSS common view is primarily used with an alternative fiber-based solution as back-up. All available time signals are measured relative to the master timescale, and that data is distributed to the other locations to be used as input in the steering of the local timescales. The NTP servers of the time nodes are directly connected to Internet Exchange points, for central, highly available and fair connectivity to the Internet. 

A nationwide fiber optic communication network utilizing state-of-the-art technologies with data modulation both in the polarization and in multi-level amplitude and phase is being deployed in Sweden. The network is operated by the Swedish University computer Network, and connects all universities and several research facilities in the country through redundant connections. Since there is a limited amount of clients connected to the network, each client will be assigned a personal wavelength. With a network that is all-optical through an advanced utilization of dynamically reconfigurable optical add and drop multiplexers, each wavelength can theoretically be connected to any other client within the network, enabling broadcasting on allocated wavelengths. The coherent modulation formats also enables signal recovery through electronic digital signal processing after detection, and no optical dispersion compensation is thereby installed. This new network scheme enables a brand new implementation of frequency and time dissemination in the network. The omission of dispersion compensation fibers enhances the symmetry in duplex fiber pair transmission. These optical add-drop installations allow for future efficient frequency and time signal broadcasting from reference nodes operated by distributors such as SP Technical Research Institute of Sweden to users connected to the network.

A fiber-based time transfer between UTC(SP) and the VLBI-station at Onsala Space Observatory has been evaluated. The transfer uses a single wavelength in an active coherent DWDM-network in unidirectional duplex fibers and is routed through Reconfigurable Optical Add-Drop Multiplexers.

When fiber optic communication networks are used for ultra-stable timing or frequency transfer, there will always be an influence of polarization variation to some extent. The variations can be induced by e.g. mechanical vibration or electromagnetic effects from adjacent power lines. The output polarization from a 120 km fiber transmission of an ultra-stable optical frequency is analyzed and the requirements of a compensation device are quantified.

The focus of the work presented here is to raise awareness of how ancillary services within the NordPool area could be of value in supporting the future grid, and who could be the provider of these services. The ancillary services considered here are not limited to the current market, but also services for future market solutions as well as services for fulfilment of grid codes. The goal is to promote the development of existing and novel solutions to increase the utilisation and thus the value of equipment within the power system. The paper includes a techno-economical categorisation of ancillary services, from a provider's perspective, presenting opportunities and competition. Furthermore, procurers of services could utilise this kind of categorisation to identify possible providers or partners. The analysis of the categorisation shows a broad range of possible providers for each service and a broad range of possible services from each provider.

This paper presents the qualification of a transient recorder used in a system for traceable measurements of Very Fast Transients. The system is designed for traceable measurements of VFT up to 100 kV, having a target settling time < 10 ns, a peak voltage error < 1\%, and a front time error < 5\%. The rise time of the digitizer is 1.6 ns at 50Ω and 1.2 ns at 1 MΩ. Step responses show settling times of 4.5 ns. A convolution method gives a peak voltage error of 0.12% and a front time error of 4.1% for 4.5ns front times. © 2018 IEEE.

To achieve the lowest loss by the Zero-Voltage Switching of a Dual Active Bridge converter, it is crucial to precisely calculate the embedded Leakage Inductance of the used Medium Frequency Transformer (MFT). An effective analytical method is proposed for calculation of the leakage inductance of the MFT with rectangular-shaped windings

Why metrology? What special value does it offer to the design and use of sustainability impact metrics, and so to the realization of the United Nations Sustainable Development Goals? One answer in short, is, "For justice." The balance scale is a universal symbol of fairness, development and equality. A second brief reply is, "For efficient markets." Common currencies for the exchange of value are well known as a key factor in lowering transaction costs and supporting property rights, both essential to market formation. The repeatedly encountered dilemma, of course, is how to design, calibrate, and use measures of economic, environmental, human, and social value that lower costs and are just in more than name alone, serving some but not others. Longer answers justify metrological traceability to consensus unit standards as a key factor in realizing the SDGs by showing how it contributes to (a) the cultivation of shared meanings and improved communication; (b) the grounding of pragmatic expressions of verified trust; (c) making real, reproducible developmental trajectories visible and manageable; and (d) creating the multilevel systems of systems required for managing and governing complex, adaptive, self-organizing forms of social, political, legislative and economic life. A more complete answer to the question, "Why metrology?," then focuses on how the SDGs' diverse stakeholder interests may be most effectively fulfilled via collective actions facilitated on the basis of shared values.

In this study, several surface topographies typical for dental implants were evaluated by different measurement techniques. The samples were prepared by machine turning, wet chemical etching and electrochemical polishing of titanium discs. The measurement techniques included an atomic force microscope (AFM), coherence scanning interferometer (CSI) and a 3D stereo scanning electron microscope (SEM). The aim was to demonstrate and discuss similarities and differences in the results provided by these techniques when analyzing submicron surface topographies. The estimated surface roughness parameters were not directly comparable since the techniques had different surface spatial wavelength band limits. However, the comparison was made possible by applying a 2D power spectral density (PSD) function. Furthermore, to simplify the comparison, all measurements were characterized using the ISO 25178 standard parameters. Additionally, a Fourier transform was applied to calculate the instrument transfer function in order to investigate the behavior of CSI at different wavelength ranges. The study showed that 3D stereo SEM results agreed well with AFM measurements for the studied surfaces. Analyzed surface parameter values were in general higher when measured by CSI in comparison to both AFM and 3D stereo SEM results. In addition, the PSD analysis showed a higher power spectrum density in the lower frequency range 10-2-10-1 μm-1 for the CSI compared with the other techniques.

How road surfaces reflect light in space is a physical characteristic that plays a key role in the design of road lighting installations: by European Standards the average luminance is the target quantity to assure the required safety conditions of the motorized road traffic. Lighting systems are designed (luminous flux installed per kilometre) to comply with the above requirement, starting from reference values of road surfaces reflection published in an old scientific document. These data are obsolete and not representative of current road surfaces, but they are still used to design current LED lighting systems. European Community funded a SURFACE project to provide to EU standard organization new traceable reference data, representative of current road surfaces used in EU. The paper presents the data collections and the impact on road lighting of using available old reference data versus SURFACE collected data of current road surfaces. Results highlight advantages in using bright pavements as well the need for introducing systems for flux control in road lighting installation to compensate for the discrepancies between current reference data and actual road surface data.

Lightning impulse measurements can be highly influenced by measurement arrangement, characteristics of high voltage divider, digitizer (transient recorder) performance, and algorithms used for parameter evaluation. The main sources of measurement errors are the non-ideal step responses of digitizer and voltage divider. This paper discusses the use of deconvolution to correct for the non-ideal step response of a digitizer, and of a large mixed divider. Correcting the step response of the complete measuring system by one part at a time is desirable because it allows to evaluate the effectiveness of the correction with trustworthy methods. Step response describes the output of a system as function of time when its input changes between two levels infinitely fast. Real life impulse digitizers and impulse voltage dividers have a finite rise time, and the response does not immediately settle to final value. Slow rise time is often the cause of error for front time parameter. Creeping response is often the cause of error for time to half-value parameter. Step response of an instrument can be determined by applying a stable, known direct voltage, which is then shorted to ground by a mercury-wetted relay. The mercury-wetted relay is assumed nearly an ideal switch, which creates almost an ideal voltage step for input of the instrument. Convolving the derivative of the measured step response with an ideal input gives a measure of distortion caused by the non-perfect step response, and conversely deconvolving the measured step response with the measured signal gives the original input signal. This paper presents an FFT-based method for step response correction using deconvolution. Deconvolution is a mathematical process, which is used to reverse the non-ideal effects of measuring instrument on recorded data. Effectiveness of the method is demonstrated by two examples. In the first example, the non-ideal step responses of the different ranges of an impulse digitizer are corrected. Functionality of the step response correction is evaluated by comparing the results against a calculable impulse voltage calibrator. Results showed that the step response correction reduced errors in lightning impulse parameters. Stability of the step response correction was analysed by studying several impulse calibration results that have been performed for the instrument within a year. The second example corrects the response of a 2400 kV impulse voltage divider. The effectiveness of the correction is evaluated by comparing its results to a 400 kV reference divider.

The effect of the coaxial cable type and length on the lightning impulse parameters is often neglected. However, studies have shown that the coaxial cable length can affect the parameters that are calculated according to IEC 60060-1:2010. This study investigates how different coaxial cables influence the impulse waveforms by measuring the input and output of the cable under test with a 2-channel digitizer. Non-standard lightning impulses were generated using an impulse voltage calibrator. Results indicate that coaxial cables attenuate the test voltage and increase both the front time and time-to-half value.

Here we demonstrate a stable and tunable method to alter the carrier concentration of epitaxial graphene grown on silicon carbide. This technique relies on chemical doping by an acceptor molecule. Through careful tuning one can produce chemically doped graphene quantum resistance devices which show long-term stability in ambient conditions and have performance comparable to that of GaAs quantum resistance standards. This development paves the way for controlled device fabrication of graphene quantum hall resistance standards, which can be reliably tailored to operate below 5 T and above 4 K out-of-the-box, without further adjustments from the end-user.

One of the aspirations of quantum metrology is to deliver primary standards directly to end-users thereby significantly shortening the traceability chains and enabling more accurate products. Epitaxial graphene grown on silicon carbide (epigraphene) is known to be a viable candidate for a primary realisation of a quantum Hall resistance standard, surpassing conventional semiconductor two-dimensional electron gases, such as those based on GaAs, in terms of performance at higher temperatures and lower magnetic fields. The bottleneck in the realisation of a turn-key quantum resistance standard requiring minimum user intervention has so far been the need to fine-tune the carrier density in this material to fit the constraints imposed by a simple cryo-magnetic system. Previously demonstrated methods, such as via photo-chemistry or corona discharge, require application prior to every cool-down as well as specialist knowledge and equipment. To this end we perform metrological evaluation of epigraphene with carrier density tuned by a recently reported permanent molecular doping technique. Measurements at two National Metrology Institutes confirm accurate resistance quantisation below 5n-1. Furthermore, samples show no significant drift in carrier concentration and performance on multiple thermal cycles over three years. This development paves the way for dissemination of primary resistance standards based on epigraphene

In the fiber optic link, connecting RISE research facilities in Borås with the Photonics Lab at Chalmers University of Technology in Gothenburg, the signal is substantially distorted by polarization variations. It has been verified that the variations are induced by the electrical power grid, however unknown at which segment of the link that it occurs. While this distortion is effectively handled by standard equipment for the data transmission, it deteriorates the detection of a transmitted ultra-stable frequency, using heterodyne mixing. Thus, the magnitude and severity of this distortion is quantified, and some compensation techniques are evaluated.

Power system security is defined as the ability of the power system to withstand the occurrence of

credible disturbances as defined by security criteria or standards. Stability control, which is one of the

pillars to system security and the subject of this technical brochure, aims at maintaining the security

of supply according to cost-effective criteria. It has always been a top priority in both industrial

practice and academic research to ensure the reliable operation of power systems. To this end,

extensive activities have already been undertaken by e.g. CIGRE in the field of power system stability

control and Dynamic Security Assessment (DSA).

Analysis from past blackouts and major system disturbances has pointed out some potential

deficiencies in current stability control techniques. These deficiencies are related to various aspects of

design and maintenance of control systems, being a direct result of the insufficient systematic design

and adaptability of, and coordination among, the conventional stability controls. According to a

questionnaire survey conducted by this JWG, the full benefits from a systematic framework approach

for power system stability were recognized by many of the respondents. All these key elements are

integrated in the framework proposed by this JWG and reflect the existing experience.

This TB proposes a framework consisting of the four established control types described below and

coordinating them to achieve enhanced performance. As fundamental requirement to achieve this

goal, the proposed framework associates these stability control types with their respective system

states. The first control type is named preventive control. It is activated in the normal or alert state,

and is carried out to maintain a sufficient stability margin. Once a predefined contingency occurs the

system could rapidly evolve towards an emergency state, where the second stability control type,

called event-based control, is triggered. The third stability control type, called response-based control,

is usually initiated following the violation of key variable limits in the emergency state. In cases where

the operation of all the previous controls proves insufficient, the system will degrade to a blackout

state. Restorative control, the fourth control type, is activated following a blackout or after an

emergency state and remains active over the whole restoration process.

This TB emphasises that these control types gain added value if they are adaptive and coordinated as

recommended in the proposed framework. When adaptive, they are able to adjust their control

decision set to the current operating condition and identify the contingencies. The coordination of

these adaptive controls yields a more cost-effective set of planned control decisions

This TB describes the functional structure of the proposed framework whose design shares the same

architecture of an online DSA system as well as the same configuration and hardware of existing

automatic control devices at substations.

This functional structure is comprised of four high-levels modules:

Wide area data acquisition and information processing,

Real-time monitoring, online estimation and online stability analysis,

Adaptive and coordinated decision planning of stability control, and

Automatic activation of event-based and response-based controls.

The first and second high-level modules are already well established in the industry. However, the

third module is not yet at the same maturity level. To this end, this TB recommends the following

elements in order to design and develop software with required functionalities in the proposed

framework: Quantitative stability analysis, Determining in advance the optimal stability control decision for each relevant control type,

and

Coordinating the previously determined stability control decisions across all control types.

This framework and its underlying software strongly rely on its integration with online DSA and other

tools used at the control centre. Besides, these systems are fed with field data from measurement

devices (e.g. PMUs) whose number and location should be effectively selected. Data exchange

protocols between all these elements are critical for their integration into the framework. Bad data

detection is a prerequisite for online monitoring and analysis, and absolutely critical for the smooth

functioning of the framework so that proper stability control decisions are always taken.

This TB also provides some key considerations and recommendations in the design and

implementation of the proposed framework for 1) specification designers, 2) manufacturers and 3)

system operators.

Before implementing such a framework, the grid owner (and also the specification designer) should

conduct a cost benefit analysis to compare its effectiveness with alternatives.

After the grid owner decides to implement such framework, demonstration projects and trial

operations have to be conducted with a particular focus on validation of

control decision planning. It is

highly recommended to develop laboratory or field validation tests for key devices and systems. These

tests need to be conducted before as well as after commissioning. Especially for event-based and

response-based controls, which operate infrequently, post-commissioning testing remains important.

It has to be mentioned that there are still some remaining issues. One of these is the execution of the

optimisation process that is quite complex and consists of an iterative search based on simulations.

Currently this optimisation does not guarantee a global optimum or even convergence. This issue

should be the focus of research and development by both manufacturers and academia. Another

major issue to be tackled by specification designers relates to cyber security aspects, which have only

been briefly touched upon in this TB. Thirdly, the remote modification of control settings is not yet a

widely accepted practice, and the proper design of operator’s intervention and validation mechanisms

is still lacking. To address these issues more effort is needed mainly from the system operator’s perspectives.

The proposed framework is expected to overcome most of the deficiencies of the current stability

controls. Yet, some challenges do remain and the following suggestions for future work are provided.

Firstly, the applicability of the proposed framework in a multi-TSO environment with common grid

model, mainly in the emergency state, needs further investigation. Secondly, power oscillations that

occasionally occur and might cause the triggering of incorrect control decisions, should be fully

understood and have their adverse consequences mitigated. Further development would be directed

towards the improvement of control decision planning by combining system-wide response

measurements with pre-disturbance simulation results. Thirdly, the stability characteristics of modern

power systems are changing due to the increasing level of power electronics devices. Its impact on

stability control needs to be properly determined in order to ensure the correct operation of the proposed framework.

In this paper, we describe the results from an ongoing project to update the modelling strategies of load models used for planning purposes by the Nordic Transmission System Operators (TSOs) Svenska kraftnät, Fingrid & Statnett. The background to this project and a description of the development of this methodology was published as Part 1 of this set of papers, presented at the Cigré 2016 Session [1]. During 2016, the methodology has been through a verification phase which is partly presented in [2] and [3] with further details presented in this paper.

The load response to voltage and frequency changes may have a significant impact on the dynamic behaviour of the power system. In this sense, the selection of load model structures and load model parameterisation gain an increased interest as power systems are operated closer to their limits. Modelling of loads is however highly complex due to the vast number of load devices in a power system, making it unfeasible to model each device separately as well as making it unfeasible to model each possible loading scenario. Based on this, a methodology for development of load models has been presented in [1]. In the work with validating this methodology, several challenges as well as strengths of the method have been identified. For the voltage dependency of the active power part of the load, the validation successfully provided evidence of the validity of the method. For reactive power, only a partial validation could be performed due to limited level of reactive power in gathered measurements. The load model structure used in this project is identified as a limiting factor for the representation of the non-linear behaviour of this part of the load. Frequency dependency of load has only been addressed to a limited extent, with results illustrating the difficulties to assess this kind of behaviour from measurements gathered during this project.

All in all, from the results of the validation it is found that the method is suitable to be employed on a larger scale with some differences in approach regarding the assessment of the voltage and frequency behaviour of the load. Furthermore, this work has provided valuable input for the understanding of the behaviour of the load.

In recent years, the impact of natural and man-made hazards on critical infrastructure has resulted in governments, regulators, utilities and other interested parties elevating requirements to enhance the ability of critical infrastructure. In this context, CIGRE C4 has established a technical working group (WG) to provide guidance in an attempt to standardise the approach to adopt resilience thinking in the utility environment. The first duty of the CIGRE C4.47 WG was to conduct an international survey to understand the existing trends of adoption and application of resilience concepts in the electricity sector. This reference paper will describe key observations and unpack the initial thoughts of the WG. Further insight into the survey observations and results can be obtained from the future CIGRE Technical Brochure.

Power system flexibility relates to the ability of the power system to manage changes. Solutions providing advances in flexibility are of utmost importance for the future power system. Development and deployment of innovative technologies, communication and monitoring possibilities, as well as increased interaction and information exchange, are enablers to provide holistic flexibility solutions. Furthermore, development of new methods for market design and analysis, as well as methods and procedures related to system planning and operation, will be required to utilise available flexibility to provide most value to society. However, flexibility is not a unified term and is lacking a commonly accepted definition. The flexibility term is used as an umbrella covering various needs and aspects in the power system. This situation makes it highly complex to discuss flexibility in the power system and craves for differentiation to enhance clarity. In this report, the solution has been to differentiate the flexibility term on needs, and to categorise flexibility needs in four categories: Flexibility for Power, Flexibility for Energy, Flexibility for Transfer Capacity, and Flexibility for Voltage. Here, flexibility needs are considered from over-all system perspectives (stability, frequency and energy supply) and from more local perspectives (transfer capacities, voltage and power quality). With flexibility support considered for both operation and planning of the power system, it is required in a timescale from fractions of a second (e.g. stability and frequency support) to minutes and hours (e.g. thermal loadings and generation dispatch) to months and years (e.g. planning for seasonal adequacy and planning of new investments). The categorisation presented in this report supports an increased understanding of the flexibility needs, to be able to identify and select the most suitable flexibility solutions.

Power system flexibility relates to the ability of the power system to manage changes. Solutions providing advances in flexibility are of utmost importance for the future power system. Development and deployment of innovative technologies, communication and monitoring possibilities, as well as increased interaction and information exchange, are enablers to provide holistic flexibility solutions. Furthermore, development of new methods for market design and analysis, as well as methods and procedures related to system planning and operation, will be required to utilise available flexibility to provide most value to society. However, flexibility is not a unified term and is lacking a commonly accepted definition. Several definitions of flexibility have been suggested, some of which restrict the definition of flexibility to relate to changes in supply and demand while others do not put this limitation. The flexibility term is used as an umbrella covering various needs and aspects in the power system. This situation makes it highly complex to discuss flexibility in the power system and craves for differentiation to enhance clarity. In this report, the solution has been to differentiate the flexibility term on needs, and to categorise flexibility needs in four categories:

 Flexibility for Power: - Need Description: Short term equilibrium between power supply and power demand, a system wide requirement for maintaining the frequency stability. - Main Rationale: Increased amount of intermittent, weather dependent, power supply in the generation mix. - Activation Timescale: Fractions of a second up to an hour.

 Flexibility for Energy: - Need Description: Medium to long term equilibrium between energy supply and energy demand, a system wide requirement for demand scenarios over time. - Main Rationale: Decreased amount of fuel storage-based energy supply in the generation mix.  - Activation Timescale: Hours to several years.

 Flexibility for Transfer Capacity: - Need Description: Short to medium term ability to transfer power between supply and demand, where local or regional limitations may cause bottlenecks resulting in congestion costs. - Main Rationale: Increased utilisation levels, with increased peak demands and increased peak supply. - Activation Timescale: Minutes to several hours.

 Flexibility for Voltage: - Need Description: Short term ability to keep the bus voltages within predefined limits, a local and regional requirement. - Main Rationale: Increased amount of distributed power generation in the distribution systems, resulting in bi-directional power flows and increased variance of operating scenarios. - Activation Timescale: Seconds to tens of minutes.

Here, flexibility needs are considered from over-all system perspectives (stability, frequency and energy supply) and from more local perspectives (transfer capacities, voltage and power quality). With flexibility support considered for both operation and planning of the power system, it is required in a timescale from fractions of a second (e.g. stability and frequency support) to minutes and hours (e.g. thermal loadings and generation dispatch) to months and years (e.g. planning for seasonal adequacy and planning of new investments).