Editorial

by Alex Apostolov, Editor-in-Chief

We Need to Integrate the DERs

There is no doubt that one of the main characteristics of the electric power systems of the twenty first century is the large penetration of distributed energy resources.

These huge machines are amazing compared to the wind mills used for centuries or the first electricity-generating wind turbines from 125 years ago. They are also connected to the electric power system in a very different way.
While at the end of the 19th century and most of the 20th century wind generators were isolated single machines predominantly used to produce electricity in rural areas without connection to the distribution system, today they can be of all sizes, connected to any level of the electric power system.
The types of generators used, the methods of connection to the system and the fact that they are not limited to covering the load at their location, but in many cases they deliver power to the system, creates a lot of challenges for the protection and control systems.

Wind is not the only renewable resource. Solar power is another major player with a very rich history as well. While at the beginning and through the centuries concentrating solar rays using mirrors or magnifying lenses was the main method that is still used today to produce steam that can be used to generate electricity, the photovoltaic effect discovered in the twentieth century resulted in the development and wide spread use of solar panels - to power your watch or calculator, home or deliver power from a solar farm to the electric power grid.

There are also many others:

  • Tidal
  • Micro-hydro
  • Fuel cells
  • Fly wheels

Just to name a few - all of them with different characteristics and different behavior during abnormal system conditions.
Further, all of them need to be integrated in the electric power system, as weAt the beginning they were not a problem from the point of view of protection, automation and control specialists – they were small, isolated and not that many. But the pressure to solve global warming by replacing fossil fuel based power production with “green power” produced by renewable energy resources, together with the advancements in technology created an environment where we now see wind generators close to 8 MW with turbines blades reaching length of 75 meters (246 feet).

ll as its protection and control systems. Also this is one of the big challenges that our industry faces, because in many cases the owners of the DERs do not understand that their single or multiple machines need to behave in a certain way during a fault on the interconnection to the system or during a wide area disturbance.

They will need to provide information about the transient and dynamic models of the DERs they are connecting to the grid.
They will need to continuously communicate with the energy management, protection and control systems.
They will need to receive commands and execute the signals.
Integration means that each individual unit has to become part of the whole, part of the system.

This will then help maintain the stability of the system during wide area disturbances.

"Sticks in a bundle cannot be broken."

Bondei Proverb

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