Islanding: what is it and how to protect from it?

Islanding is a critical and unsafe condition in which a distributed generator, such as a solar system, continues to supply power to the grid while the electric utility is down.

Islanding and distributed power generation

Islanding is a critical and unsafe condition, which may occur in a power system. This condition is caused due to an excessive use of distributed generators in the electrical grid. Before going into more detail, it is important to understand distributed generation: Solar power generators, wind generators, gas turbines and micro generators such as fuel cells, micro turbines, etc. are all examples of distributed generators.

What is islanding?

The fact that anyone could supply electricity back to the grid causes the problem of islanding. It is a condition in which a distributed generator like solar panel or wind turbine continues to generate power and feed the grid, even though the electricity power from the electrical utility is no longer present. Also, it exposes utility workers to life critical dangers of shocks and burns, who may think that there is no power once the utility power is shut down, but the grid may still be powered due to the distributed generators. [caption id="attachment_4955" align="aligncenter" width="342"] Islanding[/caption]

Anti-islanding or islanding protection

To avoid this problem, it is recommended that all distributed generators shall be equipped with which devices to prevent islanding. The act of preventing islanding from happening is also called anti-islanding.

Problems caused by islanding

Islanding causes many problems, some of which are listed below:

1. Safety Concern: Safety is the main concern, as the grid may still be powered in the event of a power outage due to electricity supplied by distributed generators, as explained earlier. This may confuse the utility workers and expose them to hazards such as shocks.
2. Damage to customers’ appliances: Due to islanding and distributed generation, there may be a bi-directional flow of electricity. This may cause severe damage to electrical equipment, appliances, and devices. Some devices are more sensitive to voltage fluctuations than others and should always be equipped with surge protectors.
3. Inverter damage: In the case of large solar systems, several inverters are installed with the distributed generators. islanding could cause problems in the proper functioning of the inverters.

Ways to detects and resolve islanding

There are many ways to detect islanding. We can categorize those as active- and passive detection methods:

Active islanding detection

Active detection methods involve the technique of constantly sending a signal back and forth between the distributed generator and the grid to ensure the status of electrical supply.

Passive islanding detection

Passive detection methods, on the other hand, make use of transients in the electricity (such as voltage, current, frequency, etc.) for detection. The quickest and easy way to prevent any problems is to shut off the distributed generator when requested by the utility.