Condition Monitoring of high voltage cables: Turning information into extra capacity

Increasing demand for power is forcing power utilities to load power cables to their physical limit, and safety and efficiency concerns are making it more and more critical for operators to understand what is happening thermally both inside the cables themselves, and along the cable route.
Real Time Determination of Thermal Conditions along HV Power Cable Systems
During high-load conditions and under emergency circumstances (such as when a failure occurs in a segment of the grid and power must be shifted to other sections to compensate) it often becomes necessary to load cables right up to the limits permitted by the relevant regulations. In these operational situations, it must be ensured that maximum temperature limits are not exceeded. Due to the increasing complexity of the thermal relationships along cable routes, the ability to continuously measure the temperatures along the cable has proven invaluable, providing critical operational data to engineers, especially in the case of a system faults such as a hot spots that could result in cable failure if they are not corrected.
The intrinsic temperature measuring system DTS based on LIOS Technology’s design, with fibre optic sensors either installed within the power cable’s cross section (FIMT – Fibre in metal tube ) or attached to the exterior of the cable, makes it possible to record the temperature profile along an entire cable route continuously, and to pinpoint the exact location of hot spots within a metre. Since the measuring principle employed is purely optical, the presence of electromagnetic influences, which can result in false sensor signals in other technologies, does not affect the DTS unit.
Distributed temperature sensing is a powerful tool that allows the accurate rating of high voltage power cables in real time, and provides the following operating benefits:

• Reduce power outages or blackouts
• Ensure continuity of supply
• Activate hidden capacity reserves of existing assets
• React quickly to overload conditions
• Conduct precisely and in real-time load predictions as new sources of energy are added to the grid

The temperature profile data, in any desired form or format, can be transmitted via standard interfaces from systems of the OTS product series as required, and be either displayed or further processed by PC, PLC or SCADA systems. As a result of the increasing demands placed on the ability to network and integrate measuring systems into management systems, LIOS offers network components that summarise DTS data from several DTS units and transport or convert it to the required network standards and protocols like Modbus, DNP3, IEC60870-5 or XML based data interfaces.
Dynamic Cable Rating
LIOS also provides an integrated Real Time Thermal Rating (RTTR) package via a well defined interface between its DTS data visualisation software and a commercialised – the industry’s de facto standard – cable ampacity program based on IEC standardised methods (mainly IEC 60287 and IEC 60853). Dynamic rating software couples the accurate temperature data provided by the DTS unit to predictive functions of cable ratings, providing engineers with even more information upon which they can base distribution and load decisions. The result is dramatically more efficient transmission of power, fewer “brown-outs”, and decreased operating costs.

The ideal sensor embedded in power cables: Fibre In Metal Tube (FIMT)

The optical fibre serves as the distributed temperature sensor for LIOS DTS systems and is typically surrounded by a protective layer. It is preferably encased in a stainless steel tube which significantly increases the mechanical stability of the sensor. Fibre encapsulated in stainless steel tube or short “Fibre In Metal Tube (FIMT)” is a hermetically sealed rugged construction for very long lengths of optical fibres. Furthermore, it is particularly effective in protecting against the hydrostatic pressures, high temperature effects and corrosive environments.
The inside of the FIMT metallic tube may lined with gel to ensure that the sensor cable remains permanently water-proof. This viscous gel protects the fibres from many environmental concerns, prevents damage from microbending conditions and helps to minimize the forces applied during spooling and deployment.
An important parameter to consider with FIMT is the Excess Fibre Length. It is defined by the percentage of excess fibre loaded into the metal tube during processing to relieve induced stresses directly related to the differing thermal coefficient of expansions of each material contained in the construction. FIMT is exposed to drastic and often rapid changes in temperature and pressure, so the Excess Fibre Length must be considered to ensure continuous, robust performance across all operational conditions.
FIMT constructions contain individual or multiple fibres (single mode or multi mode) and are available in sizes ranging from 1 mm to 3 mm outer diameter, variations in effective wall thickness are possible as well. FIMT serves as the core for various fibre optic sensor cable constructions or may be integrated into high voltage cable designs directly.
The FIMT is manufactured from a special stainless steel strip. During the manufacturing process this strip is formed to a tube and welded along its length. The stainless steel tubes must be hermetically sealed for all applications. For this reason the complete weld seam is subjected to a leak proof test by means of eddy current. By means of a drawing process the desired final diameter is attained on the one hand and an increase in strength through cold conversion on the other. During the manufacturing process the optical fibres are inserted into the tube. They are clearly differentiated by means of a specific colour code. At the end of the production process the tubes are subjected to a complete optical attenuation measurement and then documented for back-tracing. Additionally, each length produced is subjected to a weld penetration test, each weld seam undergoes a leak test, and the Excess Fibre Length is checked.
LIOS offers a variety of FIMT constructions perfectly suitable for distributed temperature sensing applications along power cable transmission systems.

DTS support for Steam Assisted Gravity Drainage (SAGD)

Accurate, continual, and real-time temperature reading along the well path can give you valuable information about the condition of both the reservoir and downhole completion provided by LIOS distributed temperature sensing (DTS). This enables you to adjust parameters and schedule maintenance for maximum hydrocarbon production and minimize downtime.

[caption id="" align="aligncenter" width="500" caption="DTS support for Steam Assisted Gravity Drainage (SAGD)"][/caption]

DTS Temperature readings allow you to:

• Enhance oil and gas recovery
• Increase production yields
• Track well production changes over time
• Reduce frequency of well interventions
• Improve reservoir management strategies
• Supply in-flow distribution along the reservoir
• Detect early water, steam (SAGD), or gas breakthrough and its location
• Observe steam flooding performance
• Verify and allocate cross flow
• Determine skin factor
• Check integrity of casing and completion
• Monitor and optimize gas lift valve operation
• Detect stuck or leaky valves, perforation inflow, porous insulation, wax deposits, hydrate precipitation, etc.

Read more: DTS Condition Monitoring in Oil & Gas Exploration

Superior Technology and Industrial Strength – State of the Art DTS Production

The LIOS' DTS (Distributed Temperature Sensing) technology has been successfully proven in critical applications like fire detection in road and rail tunnels,  power cable and transmission line monitoring, in oil & gas exploration for permanent downhole monitoring and for industrial induction furnaces surveillance, where these systems have been equipped in worldwide projects with more than 2000 permanent installations since 1997.

Key advantages of Raman OFDR distributed temperature sensing (DTS) systems by LIOS Technology:

• Reliable system design with approved key components from the telecom industry
• The OFDR technology enables to provide sophisticated temperature surveillance at commodity prices
• Invariant spatial resolution along the entire sensor length of 1 m or 50 cm even at most remote distances.
• Direct link to SCADA systems and flexible data handling
• International Approvals and Certificates – type tested and accredited
• Impressive track record of more than 2000 installations in permanent operation

At LIOS’ new facilities at Seiler Höfe, Cologne, Germany we experience ideal surrounding conditions as an industrial manufacturer of fiber optic DTS sensor systems. In conscious of the strong requirements being made in the safety market, we provide a highly proven product based on the compliance with international quality standards recognised by impartial and competent partners for type testing our products like the VdS (Association of German Property Insurers), Deloitte or EXAM and is furthermore reflected in our implemented quality management system, certified according to DIN ISO 9001 / Edition 12/2008 and our environmental management system according to ISO 14001.

• Industrial DTS production with impressive track record
• Modern and efficient production procedures
• Comprehensively type tested
• 100 % applied Factory Acceptance Test (FAT)
• Customised Site Acceptance Test (SAT) through experienced staff on site
• High Tech made in Germany

Related information on LIOS DTS technology:

• The technology behind LIOS OFDR distributed temperature sensing systems

Dynamic wind farm load patterns recorded by long range DTS

The biggest Danish utility owner has successfully completed the installation of LIOS' Single Mode DTS equipment to monitor the power cable temperature of an offshore UK wind farm. This wind farm consists of 25 wind turbines and running in total 150.000 hours/year, designed for operational usage for in total 20 years. The high voltage power cable route is approx 20km long and connecting the offshore substation to a substation onshore. The DTS system provides real time distributed temperature sensing of the HV cable sections subsea and those inside the towers and ensures save and stable grid operation. Furthermore it helps activating hidden capacity reserves during dynamic transmission requests.

Read more:

Distributed temperature monitoring of power cables

This post is part of Blog Action Day 2009.

Reliable Energy Supply for the city of Graz, Austria

In order to improve the energy supply for the city of Graz, CCC GmbH Berlin installed new cable connections across the town between the transformer stations of Graz-South and Graz-West. The entire underground engineering, i.e. the joint base installation mand complete trenching construction was built by STEWEAG-STEG GmbH. The new cable installation is one of the city’s main transmission lines and is heavily loaded. In order to optimize the transmission performance and to guarantee its secure reliability, the cable installation has been equipped with large scale cross-bonding systems at its sheath. In addition, by the help of the LIOS Distributed Temperature Sensing (DTS) system, the level of backup capacity can be assessed. These optical fibres can monitor the cable temperature along the trench and have been integrated into the sheath area of the cable.

Highlights

• 110 kV high-voltage power cables between transformer stations Graz-South and Graz-West
• 3 cable lines with a length of 3,2 km each (total 9,6 km cable),one of which is equipped for the entire distance of 3,2 km with integrated optical fibres in a steel tube integrated in the copper screen of the HV-cable for temperature monitoring (DTS)
• 18 sets of accessories
• Cross-bonding system in order to maximize transmission performance
• During the planning period numerous calculations for currentcarrying capacity were carried out in order to judge the influenceof crossing long-distance heating lines.
• Direct DTS data interface for temperature and operational data into the overall SCADA system of STEWEAG-STEG (Fernwirkanlage STEWEAG-STEG) using protocol IEC 60870-5-104

NKT group to decrease emission of CO2 by 12 percent over three years

“Recycling and the environment have been an integral part of NKT’s working agenda for many years. But our ambition is to be even greener,” says NKT’s CTO Søren Isaksen.

Over the next three years NKT will cut corporate carbon emission by a further 12%. The announcement of this specific target is a direct result of NKT’s decision last year to join the Carbon Disclosure Project.

“When submitting our first report to the Carbon Disclosure Project we could see that we had actually exceeded our own expectations. In the period 2001 to 2008, in our cable business, we reduced CO2 emission relative to output by 48%. So we feel we are already well on the way,” says Søren Isaksen, Chief Technology Officer for the NKT Group.

“However, this does not prevent NKT from setting new targets,” stresses Søren Isaksen. “In future, the ability to document carbon dioxide emission will be an important competitive parameter. Just as we impose demands on our suppliers, our customers impose demands on us. In this way, all players in the supply chain influence the environmental and carbon balance sheets.”

For more information on the Carbon Disclosure Project see:

• Carbon Disclosure Project to assess world business CO2 footprint


• Carbon Disclosure Project


• NKT lowers CO2 emission

Setting Standards for Highly Reliable DTS Performance

LIOS Technology GmbH is the leading manufacturer of industrial DTS systems with an impressive track record of more than 2000 installations in permanent operation. Its current DTS product series was carefully designed and thoroughly tested targeting reliable performance and smooth operation in industrial environments.
This was imposingly endorsed by the latest statistical field analysis in respect of a mean time between failures (MTBF) evaluation. Adapted from field data of our installed base of the current DTS product series an excellent MTBF figure of 28 years was reached.

High reliability is also a result of the unique optical frequency-domain reflectometry (OFDR) technology of the LIOS DTS systems. In contrast to time-domain technology using pulsed lasers with high peak powers, the LIOS OFDR DTS uses a quasi-continuous laser with low peak power resulting in a nonexistent wear out of the laser unit or any other fatigue of other optical components. The exceptional reliability favors the deployment of the LIOS DTS systems in all remote, safety-relevant and industrial applications.

Electricity for all, the smart way – visit LIOS at Power Indonesia 2009

LIOS Technology GmbH- Linear Optical Sensors is pleased to invite you to attend Power Indonesia 2009 - the 14th International Power Generation, Transmission and Distribution Exhibition, taking place 14-17 October at the Jakarta International Expo, Kemayoran.

Booth number: A340

In cooperation with our partner Anugrah Mitra International & Anugrah Mira Nusantara we proudly present continuous and cost-effective monitoring solutions for the electric transmission and distribution grid, which are the essential success factors of Smart Grid implementations.

The LIOS DTS product line comprises a range of real-time fibre optic based linear temperature measuring devices (Distributed Temperature Sensing, DTS). LIOS offers Real Time Thermal Rating/ Dynamic Cable Rating (RTTR/ DCR) solutions for ampacity predictions of the power cable and overhead transmission line installation transparently integrated with its field proven DTS systems.

The Electric Indonesia Series 2009 provides a one stop shop for the major elements in the development of the country's electrical sector. For power generation, transmission and distribution Power Indonesia is South East Asia‘s most comprehensive exhibition.
This year over 600 companies from 34 countries will participate showing the huge potential in Indonesia’s Power and Electric Industries. Regional & National Pavilions from Taiwan, Korea, Germany, Czech Republic, Spain, Italy, Singapore, UK, and China will showcase the latest technology and equipment to help meet the countries huge demand for additional power.
Under its vision "Electricity for all", the Government is currently planning to increase power generation by 35,000MW by 2015 at an investment of over US$40Billion.

We look forward to seeing you in Jakarta!

Read more:

	For more information on Power Indonesia 2009 click here
	Distributed temperature monitoring of power cables

Investments in Smartgrid Technologies encourage LIOS to open US office

LIOS Technology, leading provider of state of the art frequency domain based distributed temperature monitoring solutions (DTS), announced today that it has opened an office in Morganville, New Jersey to service the growing demand for distributed temperature solutions in the United States. The New Jersey office expands LIOS’ ability to offer local sales and support services to its fast growing base of customers and prospects in the North-American market.

Corporations in the United States have been strong adopters of DTS solutions particularly in the power industry where the security, reliability and performance of temperature monitoring systems are critical.

"Especially with the SGIG (Smart Grid Investment Grant Program) we are experiencing growth in market demand and level of interest in our products and solutions," said Konrad Linckh, director of the LIOS New Jersey office. „Our customers are expanding their commitment to ensuring the reliability and performance of the transmission and distribution systems they operate. The continuous and cost-effective grid monitoring solution offered by LIOS supports that commitment and is the essential success factor of Smart Grid implementations.”

The new office is located at:

LIOS Technology Inc.
1400 Campus Drive West
Morganville, NJ 07751, USA

Tel: +1 (732) 970-8062
Fax: +1 (732) 972-4410

Success story for permanent downhole sensing - Maximize your ROI with DTS

Technology is the key driver in the quest for greater efficiency. In the oil and gas industry, there is keen interest and high demand for low-cost, reliable, and easily installable systems to enhance downhole production and recovery.

“Installation of LIOS DTS in the Darat Field in Brunei has proven to increase the value of the wells from our customer significantly because of early detection of faulty gas lift valves, resulting in quick repair and increased production.”

Lt Col (B) Mahmod Yakop (Founder & Managing Director, AMRTUR Corporation Sdn. Bhd)

In a co-operation between Shell International Exploration and Production (SIEP) and LIOS Technology GmbH (LIOS) the feasibility and economical added value of permanent downhole temperature sensing have been successfully demonstrated in a number of recently deployed on- and offshore projects in Brunei BSP. This shows that once certain maturity and robustness in a technology has evolved and an agreement on standards has been implemented low-cost equipment can be designed, manufactured, and deployed even for low-cost wells. The applied design and working practices enable permanent in-well sensing for a large-scale role out. Additionally, a common database has been developed and successfully deployed. The reservoir engineers in BSP have now full access to the low-cost DTS installed wells around the clock, every day of the year.