Finding reserves on the electrical grid

May 11, 2011

The weather determines how much energy wind turbine systems provide. The same applies to power line capacity. On cold and stormy days, this capacity is higher than on days with no wind and high mid-summer temperatures. An autonomously powered sensor network monitors power lines to find the reserves in the lines.

When storms lash northern and eastern Germany, it regularly gets tight in the and highest-voltage electrical grids. from has priority on the grid. But, on stormy days in particular, wind turbine systems must be taken offline, because the gird capacities are insufficient. “Currently we are in a situation where we have high inflows from renewable energies into our high voltage line system and are expecting large increases in the future. However, the grid is not designed for this level of energy feed,” reports Hanjo During of envia Verteilnetz GmbH in Halle, Germany, Additional are being planned. But the authorization processes could take years and very often fail due to the resistance of the people living near the projected path of the lines.

For this reason, the grid operators are already utilizing various line-monitoring procedures to increase the grid capacity over the short term: They utilize reserves that are the result of a standardized assumption regarding the worst conditions for operating the line and the actual state of the line. In favorable weather conditions, they were therefore able to increase the transmission capacities by 20 percent or more. Currently, Amprion and envia Verteilnetz are testing a new type of autonomously powered sensor network to monitor 110 kV and 380 kV lines. It is being developed jointly with the Fraunhofer Institutes for Reliability and Microintegration IZM in Berlin and Electronic Nanosystems ENAS in Chemnitz, Germany as well as other research and industrial partners in the “ASTROSE” project. “Our autonomously powered sensor network can be retrofitted easily and does not require additional infrastructure,” says Dr. -Ing. Volker Großer from the IZM. In contrast to the current monitoring systems it supplies measurement data from a tight-knit sensor network directly attached to the conductor wires.

How much current can be transmitted by a power line depends very much on temperature. If the conductor wires heat up as a result of flowing current or the sun, they expand and sag. If the sagging conductor wire gets too close to the ground, buildings, vehicles or humans, there is a risk of electrocution. To rule this out, prescribed safety clearances are mandatory. At the same time, the permitted current flow is calculated under the assumption that the ambient temperature is 35 °C and that the wind’s velocity will not exceed 0.6 m/s. However, high midsummer temperatures often bring with them a lull in the wind. Most wind turbine systems will only start to operate once wind velocity has reached 3 m/s. They deliver high amounts of electricity during fall and in winter when the power lines are effectively cooled by the weather.

To better utilize these reserves in the grid without compromising safety, the ASTROSE project partners equip the 110 kV and 380 kV lines with „eGrains.“ Cylindrical sensor nodes are wrapped around the conductor wire approximately every 500 meters. „They consist of two half cups that are clamped on and attached to each other. The ASTROSE-eGrains measure the cable‘s angle of inclination, the current flow, the temperature as well as wind movement. All measurement values are relayed from eGrain to eGrain to the next transformer station and there they are fed into the central monitoring and control system or rather made available to the internet-based remote maintenance systems of the grid operators,“ explains Großer. The ASTROSE eGrains pull the energy they require from the electrical field that surrounds the conductor wires. However, the ASTROSE does not only help utilize the capacities of the power lines better. It also reports dangerous line sags, such as can occur in winter as a result of ice build-up on the lines. The sensor node can be seen at the "Sensor + Test" tradeshow from June 7 – 9 in Nuremberg, Germany, in Hall 12, Booth 231.

Explore further: Faster computation of electromagnetic interference on an electronic circuit board

add to favorites email to friend print save as pdf

Related Stories

Saving energy with power grid of the future

Nov 02, 2010

Green energy too comes out of the electricity socket, but to get there it has to travel a long journey – from wind turbines in the North Sea or regional solar, wind and biogas power plants. On the way ...

Engineers find new way of utilizing solar farms at night

Aug 17, 2010

(PhysOrg.com) -- New technology from The University of Western Ontario utilizing photovoltaic (PV) solar farms at night will help in connecting more renewable energy sources like wind turbines to Ontario's grid, increasing ...

Intelligent networking of wind farms

Apr 06, 2010

The EU member states have passed a resolution requiring one fifth of their electricity needs to be derived from renewable energy sources by 2020, with wind farms covering a large part of this requirement. ...

A world record in direct current transmission

May 03, 2011

Siemens is building power converter stations for a high-voltage direct current (HVDC) transmission system with a record capacity of 2 x 1,000 megawatts. Beginning in 2013 the new HVDC PLUS technology will ...

Securing America's power grid

Jun 27, 2006

Terrorists attack Colombia's electrical grid hundreds of times a year. What's to stop attacks on America's power lines? An Iowa State University research team led by Arun Somani, chair and Jerry R. Junkins professor of electrical ...

Recommended for you

A smart prosthetic knee with in-vivo diagnoses

Apr 22, 2014

The task was to develop intelligent prosthetic joints that, via sensors, are capable of detecting early failure long before a patient suffers. EPFL researchers have taken up the challenge.

Old tires become material for new and improved roads

Apr 22, 2014

(Phys.org) —Americans generate nearly 300 million scrap tires every year, according to the Environmental Protection Agency (EPA). Historically, these worn tires often end up in landfills or, when illegally ...

Students take clot-buster for a spin

Apr 21, 2014

(Phys.org) —In the hands of some Rice University senior engineering students, a fishing rod is more than what it seems. For them, it's a way to help destroy blood clots that threaten lives.

User comments : 0

More news stories

Amazon Prime wins streaming deal with HBO

Amazon scored a deal Wednesday to distribute old shows from premium cable TV channel HBO to its monthly Prime subscribers, landing a blow on rival Netflix in the streaming video battle.

Is nuclear power the only way to avoid geoengineering?

"I think one can argue that if we were to follow a strong nuclear energy pathway—as well as doing everything else that we can—then we can solve the climate problem without doing geoengineering." So says Tom Wigley, one ...

Robot scouts rooms people can't enter

(Phys.org) —Firefighters, police officers and military personnel are often required to enter rooms with little information about what dangers might lie behind the door. A group of engineering students at ...

Cyber buddy is better than 'no buddy'

A Michigan State University researcher is looking to give exercise enthusiasts the extra nudge they need during a workout, and her latest research shows that a cyber buddy can help.