by Alex Apostolov, Editor-in-Chief
Before we can start thinking about PAC in the future grid, we need to make clear that we understand what we will consider the future grid and then we can talk about how we are going to protect and control it.
So, the future grid is the one that we are going to have in the period of time following the moment that I am writing this column. The future is a concept that we can spend a lot of time talking about, but we can summarize it by saying that it is something that does not really exist and we can try to predict what it will look like based on what has happened in the past and the trends that we have identified that can help us understands what it may be.
Based on the observations from the last few decades and the trends of global warming we can see that the future grid is going to be quite different from what we have had in the past. In the last 100 years we got used to power systems with power stations of different sizes generating electric power that was delivered to the customers in the load centers over the transmission and distribution system.
It has been a system that provides short circuit currents during a fault that are detected by protection devices based on different operating principles that operate as quickly as possible to selectively isolate the faulted component of the system.
However, due to global warming, since the beginning of this century we have been trying to switch from fossil fuel based generation to renewable energy resources that typically have inverter based interfaces to the grid with completely different behavior than the synchronous generators that we are familiar with.
That is why we decided to dedicate this issue of the magazine to the protection, automation and control of the future grid.
We have a collection of very interesting articles that are touching different aspects of the challenges that the future grid represents. All of this is a concern to the industry and that is why CIGRE established a working group to look at the issues. The results from this work were published in a brochure that is summarized in the cover story.
Since the inverter-based interfaces to the grid are quite different, we need to understand how they behave when a fault occurs and based on this make decisions on how to better protect the electric power transmission system using advanced and innovative technologies.
One of the solutions is the use of traveling wave-based protection, which is not dependent on the level of the fault current. But the introduction of new protection technology introduces challenges of its own and that is why we have included an article analyzing such protection systems to make sure they can be efficiently tested.
Another typical component of the future grid is the microgrid which can be isolated from the electric power system during wide area disturbances and operate based on its own energy resources. Detecting the disconnection from the grid, balancing the available generation and load and protecting the microgrid are very interesting topics that have been the subject of the work of different working groups in the IEEE Power Systems Relaying and Control Committee and they are summarized in an article included in this issue.
One of the biggest challenges, especially with the availability of more and more wind and solar power plants that are delivering hundreds of megawatts of electric power to the grid is how to deliver this power to the load centers considering that the locations with sufficient wind and sun are remotely located from the load. Building new transmission lines to deliver this power is very challenging as well because of cost and environmental concerns. That is why we also have an article about revisiting six phase transmission. Considering the large number of double circuit lines all over the world and understanding that we can increase the amount of power that each one of them can carry by 73% gives us a very powerful tool to solve this problem.
All the PAC Systems in the future grid will be communications based in order to meet the performance requirements. However, this will expose them to cyber-attacks and that is why we have also included the article describing the cyber security strategies for the grid of the future.
“The future depends on what you do today”