This work is funded under grant no. 03ET7522B, "iMonet - Intelligentes Monitoring von Betriebsanlagen für künftige Stromnetze", by the Bundesministerium für Wirtschaft und Energie (BmWE)

Partners:Siemens AG, Corporate Technology, Research in Digitalization and Automation (CT RDA SII SSI-DE), ErlangenLehrstuhl für Hochfrequenztechnik (LHFT), Friedrich-Alexander-Universität Erlangen-NürnbergAdvanced Optics Solutions GmbH, Dresden

§ The trend towards renewable energies leads to new technologies in electrical energyfacilities such as high voltage direct current (HVDC) transmission

§ Continuous monitoring of all components is indispensable to guarantee safe operationunder quickly changing load conditions

§ Most conventional sensors are not suitable for this purpose due to the prevailing harshconditions (strong electromagnetic fields, high temperature)

§ Optical sensors overcome these limitations and enable entirely new possiblities suchas distributed temperature sensing

Motivation

HVDC converter station (Copyright: Siemens)

§ A continuous-wave light source is modulated in intensity with frequencies up to a few GHz and backscattered light is detected by fast photodiodes

§ An optical filter bank separates Rayleigh-/FBG and Raman Stokes and anti-Stokes components into three channels

§ A vector network analyzer (VNA) measures the electrical frequency response H(f ) for each channel

Incoherent Optical Frequency Domain Reflectometry (IOFDR) Setup

The Bragg wavelength of fiber Bragg gratings (FBGs)λB

depends on the temperature

Hotspot Temperature Sensing

§ The ratio between the power in the Stokes and anti-Stokes channel depends on the temperature of the fiber

§ IOFDR is used to determine a spatially resolved temperature profile along the sensor fiber

Distributed Temperature Sensing

Wavelength in nm

Back

scatt

ere

d p

ow

er

in d

Bm

/nm

Raman anti-StokesRayleighRaman Stokes

Anti-Stokes power showsmajor temperature

sensitivity

Rayleigh istemperature independent

Stokes power showsminor temperature

sensitivity

Measured Rayleigh and Raman backscatteringfrom 300 m of Corning

HI1060FLEX fiber

Avalanchephotodiodes

Tunable laser source

MZM

Vectornetworkanalyzer(VNA)

PC

contr

ol &

sig

nal pro

cessin

g

Circulator1 2

3RF paths

RF amplifier

Intensitymodulator

Ramananti-Stokes

1

2

Reflected andbackscattered

light

Data

Singlemodefiber

Opticalfilterbank

Rayleigh/FBGs

RamanStokes

Opticalpaths

3

4

RayleighRaman StokesRaman anti-Stokes

Distance in m

Back

scattere

d p

ow

er

in d

Bm

/m

300 m of CorningHI1060FLEX fiber

measured in climatechamber

http://forschung-stromnetze.info

Publications:[1] "Quasi-Distributed Fiber Bragg Grating Sensing Using Stepped Incoherent Optical Frequency Domain Reflectometry," IEEE J. Lightw. Tech., accepted for publication (Sep. 2016), preprint available . http://dx.doi.org/10.1109/JLT.2016.2614581[2] "Spatially resolved fiber Bragg grating sensing using wavelength scanning incoherent OFDR," in Proc. OFC Conference, Optical Society of America, Anaheim, USA, M2D.2 (2016).

iMonet - Intelligent Monitoring of Facilities in Next Generation Power Grids

(Intelligentes Monitoring von Betriebsanlagen für künftige Stromnetze)