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Islanding Detection in Power Systems

Stråth, Niklas LU (2005)
Abstract
As the contribution of dispersed or distributed energy resources (DER) to

the electric power production increases, the effects on the power system

grow more important. As an example a critical situation may arise if

protective relays trip a large part of the dispersed generation due to

undervoltage at a short-circuit event. On the other hand it is crucial that the

protection system acts correctly to protect life and property in other

situations. These qualities are referred to as security and dependability.

There are a number of different kinds of anti-islanding or loss-of-mains

protections. Some are implemented in practice while others are still on a

research... (More)
As the contribution of dispersed or distributed energy resources (DER) to

the electric power production increases, the effects on the power system

grow more important. As an example a critical situation may arise if

protective relays trip a large part of the dispersed generation due to

undervoltage at a short-circuit event. On the other hand it is crucial that the

protection system acts correctly to protect life and property in other

situations. These qualities are referred to as security and dependability.

There are a number of different kinds of anti-islanding or loss-of-mains

protections. Some are implemented in practice while others are still on a

research level. This thesis provides an analysis of benefits and drawbacks

of methods that are applied today. The ability of the different methods to

avoid nuisance tripping and provide robust protection is investigated.

To draw the attention to industrial experience, some cases are described

where dispersed generations were nuisance tripped. Recordings from

islanding events are presented and analyzed. Performance of present anti

islanding protections is commented.

A comparison of grid codes in Sweden, Denmark and Germany serves as

an example of the situations in different countries. Today there are

differences in the connection requirements depending on different designs

of the distribution systems. These varying requirements lead to different

demands on the islanding detection devices. The thesis summarizes the

technical requirements on the islanding portion of the protection system.

To compare the protection algorithms, they are exposed to challenging

situations in a common simulation environment. In the simulation model, a

DER-unit (induction generator) is connected to a typical distribution grid.

The grid consists of two 20 kV feeders connected to a 130 kV network

equivalent via a common bus bar and a transformer. Additional feeders are

modeled with generic load and shunt capacitances.

The concept of distributed energy resources is moving from being a local

issue towards a system issue. The islanding protection devices being used

in the future have to reflect this. The thesis aims at describing this process

and ends with a list of possibly unresolved issues. (Less)
Please use this url to cite or link to this publication:
author
supervisor
organization
publishing date
type
Thesis
publication status
published
subject
pages
113 pages
publisher
Department of Industrial Electrical Engineering and Automation, Lund Institute of Technology
ISBN
91-88934-42-X
language
English
LU publication?
yes
id
245b95d4-ad84-40ed-82bd-c900a3eed07e (old id 587932)
alternative location
http://www.iea.lth.se/publications/Theses/LTH-IEA-1051.pdf
date added to LUP
2007-10-30 09:32:19
date last changed
2016-09-19 08:45:14
@misc{245b95d4-ad84-40ed-82bd-c900a3eed07e,
  abstract     = {As the contribution of dispersed or distributed energy resources (DER) to<br/><br>
the electric power production increases, the effects on the power system<br/><br>
grow more important. As an example a critical situation may arise if<br/><br>
protective relays trip a large part of the dispersed generation due to<br/><br>
undervoltage at a short-circuit event. On the other hand it is crucial that the<br/><br>
protection system acts correctly to protect life and property in other<br/><br>
situations. These qualities are referred to as security and dependability.<br/><br>
There are a number of different kinds of anti-islanding or loss-of-mains<br/><br>
protections. Some are implemented in practice while others are still on a<br/><br>
research level. This thesis provides an analysis of benefits and drawbacks<br/><br>
of methods that are applied today. The ability of the different methods to<br/><br>
avoid nuisance tripping and provide robust protection is investigated.<br/><br>
To draw the attention to industrial experience, some cases are described<br/><br>
where dispersed generations were nuisance tripped. Recordings from<br/><br>
islanding events are presented and analyzed. Performance of present anti<br/><br>
islanding protections is commented.<br/><br>
A comparison of grid codes in Sweden, Denmark and Germany serves as<br/><br>
an example of the situations in different countries. Today there are<br/><br>
differences in the connection requirements depending on different designs<br/><br>
of the distribution systems. These varying requirements lead to different<br/><br>
demands on the islanding detection devices. The thesis summarizes the<br/><br>
technical requirements on the islanding portion of the protection system.<br/><br>
To compare the protection algorithms, they are exposed to challenging<br/><br>
situations in a common simulation environment. In the simulation model, a<br/><br>
DER-unit (induction generator) is connected to a typical distribution grid.<br/><br>
The grid consists of two 20 kV feeders connected to a 130 kV network<br/><br>
equivalent via a common bus bar and a transformer. Additional feeders are<br/><br>
modeled with generic load and shunt capacitances. <br/><br>
The concept of distributed energy resources is moving from being a local<br/><br>
issue towards a system issue. The islanding protection devices being used<br/><br>
in the future have to reflect this. The thesis aims at describing this process<br/><br>
and ends with a list of possibly unresolved issues.},
  author       = {Stråth, Niklas},
  isbn         = {91-88934-42-X},
  language     = {eng},
  pages        = {113},
  publisher    = {ARRAY(0x85ac6b8)},
  title        = {Islanding Detection in Power Systems},
  year         = {2005},
}