Do we really need Time?
When we think about time, there are so many questions that we can ask. Can we exist without the concept of time in our everyday life? Can we have protection and control systems without considering time? What time is it?
I can probably fill this whole page with questions related to time, but instead I will focus just on a couple of issues.
As usual, let’s first look at the definition of time. It is defined as the duration in which all things happen, or a precise instant when something happens.
If we look at the world around us, we can see that most of it exists without time. All creatures, except most humans, do not have calendars and clocks. They live in the moment, based on their sensors that tell them what to do at that moment. And even humans have been living like this for years. If we reach a state of enlightenment and we are able to live in the moment – we don’t need time, because past and future do not exist. Only “now” exists. So, we don’t need to worry about when something happened in the past, when it will happen in the future or how long it will last.
However, with human evolution we started developing as very different kind of beings – observing the stars and the movements of the planets, asking questions about what the world around us is, growing plants and raising animals for food. We started learning from the past and planning for the future, so we can improve the efficiency of our existence. And this is why the ancient people started first developing calendars and introducing the concepts of time, and the methods and tools for how to measure it. From sundials and water clocks at the beginning, we are now using satellites synchronized clocks to coordinate our daily activities.
A similar thing happened in the protection and control industry. It has existed for less than a couple of hundred years and started at a time when we already had a well-established concept about time, we had clocks and watches. However, the electromechanical devices had no idea about what time it is and when an operation occurred. If the relay tripped during a fault, in the best case we have a target indicating that it operated. Maybe it also showed which was the faulted phase. But we had no idea at what time the fault occurred. We didn’t have the technology and the power system was different.
The development of microprocessor relays changed all of that, because now they had a clock. We set the time and when a fault occurs, we have a time stamp telling us when it happened. If it is a single relay operation, knowing the approximate time of the event is good enough. But if we have multiple relays operating within the same period of time, how do we know if there was a mis-operation?
This is when we started thinking about and requiring time synchronization. We decided that for proper analysis of protection operation and wide area disturbances the accuracy of the time synchronization of all devices needs to be at least 1 msec.
In this new century we live in the world of Smart Grid, digitization and IEC 61850. We have synchrophasor measurements and merging units that need to be synchronized with 1 microsecond accuracy based on GPS and other satellite signals from atomic clocks. Time has become a critical component for the efficient management of the changing electric power grid.
That is the reason to focus this issue of the magazine on the different aspects of time and its impact on protection, automation and control systems. To talk about time settings and measurements, time synchronization standards and networks, time models and latency and many other time related issues. Because in the PAC world, we need to know when things happen.
“The only reason for time is so that everything doesn’t happen at once.”