Improving sensor accuracy to prevent electrical grid overload

November 7, 2017, American Institute of Physics
Credit: CC0 Public Domain

Electrical physicists from Czech Technical University have provided additional evidence that new current sensors introduce errors when assessing current through iron conductors. It's crucial to correct this flaw in the new sensors so that operators of the electrical grid can correctly respond to threats to the system. The researchers show how a difference in a conductor's magnetic permeability, the degree of material's magnetization response in a magnetic field, affects the precision of new sensors. They also provide recommendations for improving sensor accuracy. The results are published this week in AIP Advances.

With the addition of new renewable energy sources and smart homes demanding more information, the is becoming more complex. Author Pavel Ripka said, "If you have [a] at the edge of capacity, you have to be careful to monitor all the transients (power surges)." Surges are overloads or failures to the system, which can be caused by something as simple as a broken power line, or more dramatic events like lightning strikes or geomagnetic storms.

Ripka explained the importance of monitoring electrical currents: "Every day you get a lot of these small events (surges) within a big power grid, and sometimes it is difficult to interpret them. If it is something really serious, you should switch off parts of the grid to prevent catastrophic damage, but if it's a short transient which will finish fast there is no need to disconnect the grid. It's a risky business to distinguish between these events, because if you underestimate the danger then parts of the distribution installations can be damaged causing serious blackouts. But if you overestimate and disconnect, it is a problem because connecting these grids back together is quite complicated," he said.

To address the increasing complexity of the grid and power outage threats, there has been an increase in use of ground current sensors in the past couple of years. New yokeless current sensors are popular because of their low cost and compact size. These sensors are good for assessing currents in nonmagnetic conductors such as copper and aluminum. However, ground conductors are usually iron due to its mechanical strength, and iron has a high magnetic permeability.

Using these new sensors to measure ground currents when iron is present is a bit like using a thermometer to assess if the heating needs to be switched on, not taking into account where exactly the thermometer is placed. Near a door or window, the thermometer's reading can be affected differently than elsewhere. In the same way, this study has shown that not taking into account the magnetic permeability of a conductor distorts the accuracy of a reading with a yokeless sensor.

Ripka and his team matched experimental measurements with theoretical simulations to highlight the difference in yokeless sensor readings between nonmagnetic and magnetic conductors.

"We can show how to design (yokeless) current sensors so that they are not so susceptible to this type of error," Ripka said. "[This study is] just a small reminder to make [engineers] design sensors safely."

To further prove the point, Ripka's group is starting to take long-term readings at power stations, comparing results to commercial uncalibrated . In the future, Ripka envisions cooperating with geophysicists to correlate ground currents and geomagnetic activity, to better understand how these currents are distributed within the earth and even predict future disruptions to the grid.

Explore further: Detecting short circuits by going back in time

More information: M. Mirzaei et al, The effect of conductor permeability on electric current transducers, AIP Advances (2017). DOI: 10.1063/1.4994195

Related Stories

Detecting short circuits by going back in time

July 10, 2017

It took EPFL researchers only three minutes to detect and locate a short circuit triggered intentionally in the power grid serving Fribourg Canton. The researchers, using a computer and a single sensor, spotted it by "going ...

Measurements help defend grid against space weather

July 2, 2013

Since the invention of the telescope four centuries ago, astronomers have become more aware of the active nature of the Sun, and how events on its surface can affect the Earth. One of the most dramatic of these is 'space ...

Recommended for you

Researchers turn light upside down

February 23, 2018

Researchers from CIC nanoGUNE (San Sebastian, Spain) and collaborators have reported in Science the development of a so-called hyperbolic metasurface on which light propagates with completely reshaped wafefronts. This scientific ...

Recurrences in an isolated quantum many-body system

February 23, 2018

It is one of the most astonishing results of physics—when a complex system is left alone, it will return to its initial state with almost perfect precision. Gas particles, for example, chaotically swirling around in a container, ...

Hauling antiprotons around in a van

February 22, 2018

A team of researchers working on the antiProton Unstable Matter Annihilation (PUMA) project near CERN's particle laboratory, according to a report in Nature, plans to capture a billion antiprotons, put them in a shipping ...

Urban heat island effects depend on a city's layout

February 22, 2018

The arrangement of a city's streets and buildings plays a crucial role in the local urban heat island effect, which causes cities to be hotter than their surroundings, researchers have found. The new finding could provide ...

New quantum memory stores information for hours

February 22, 2018

Storing information in a quantum memory system is a difficult challenge, as the data is usually quickly lost. At TU Wien, ultra-long storage times have now been achieved using tiny diamonds.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.