Featured Research

from universities, journals, and other organizations

Finding reserves on the electrical grid

Date:
June 20, 2011
Source:
Fraunhofer-Gesellschaft
Summary:
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.

Autonomously powered sensor nodes can detect reserves in the electrical grid.
Credit: © Fraunhofer IZM

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.

Related Articles


When storms lash northern and eastern Germany, it regularly gets tight in the high-voltage and highest-voltage electrical grids. Electricity from renewable resources 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 power lines 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 weather 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 Groίer 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 Groίer. The ASTROSE eGrains pull the energy they require from the electrical field that surrounds the conductor wires. However, the ASTROSE sensor network 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.


Story Source:

The above story is based on materials provided by Fraunhofer-Gesellschaft. Note: Materials may be edited for content and length.


Cite This Page:

Fraunhofer-Gesellschaft. "Finding reserves on the electrical grid." ScienceDaily. ScienceDaily, 20 June 2011. <www.sciencedaily.com/releases/2011/05/110511104521.htm>.
Fraunhofer-Gesellschaft. (2011, June 20). Finding reserves on the electrical grid. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2011/05/110511104521.htm
Fraunhofer-Gesellschaft. "Finding reserves on the electrical grid." ScienceDaily. www.sciencedaily.com/releases/2011/05/110511104521.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Lava Inches Closer to Highway

Raw: Lava Inches Closer to Highway

AP (Dec. 21, 2014) — Officials have opened a new road on Hawaii's Big Island for drivers to take care of their daily needs if encroaching lava from Kilauea Volcano crosses a highway and cuts them off from the rest of the island. (Dec. 20) Video provided by AP
Powered by NewsLook.com
Raw: Scuba Diving Santa Off Florida Keys

Raw: Scuba Diving Santa Off Florida Keys

AP (Dec. 20, 2014) — A scuba diving Santa Claus explored the waters of the Florida Keys National Marine Sanctuary. Dive shop owner Spencer Slate makes the dive each year to help raise money for charity. (Dec. 20) Video provided by AP
Powered by NewsLook.com
Obama: Better Ways to Create Jobs Than Keystone Pipeline

Obama: Better Ways to Create Jobs Than Keystone Pipeline

AFP (Dec. 19, 2014) — US President Barack Obama says that construction of the Keystone pipeline would have 'very little impact' on US gas prices and believes there are 'more direct ways' to create construction jobs. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com
Raw: Lava on Track to Hit Hawaii Market

Raw: Lava on Track to Hit Hawaii Market

AP (Dec. 19, 2014) — Lava from an active volcano on Hawaii's Big Island slowed slightly but stayed on track to hit a shopping center in the small town of Pahoa. (Dec. 19) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins