IEEE Power and Energy Society (PES) Brac University Student Branch Chapter hosted a webinar on “Power System Protection in the Distribution Sector ” on 23rd April 2022. The webinar was conducted by Md. Ariful Islam, Assistant Engineer, SPS, DPDC. Sometimes, there might be a faulty section in the electrical power system. The objective of power system protection is to isolate this faulty section from the rest of the live system so that rest of the system can function accordingly and properly without causing any damage due to fault current.
The speaker started by explaining the required amount of power needed in our daily lives in Bangladesh. We learned about the generation capacity, peak demand, and maximum generation of power in our country. A blackout in 2014 resulted in not having proper access to electricity all across Bangladesh which caused inconvenience to about 100 million Bangladeshis. The national grid lost around 445MW of power and it took about 10 hours to get everything back on track. So, it is one of the most important parts of our daily lives. Without proper supply and generation of electricity, our daily lives would almost become futile. Hence, power system protection is a salient factor in everyone’s lives.
With that being said, we learned when to identify a fault in the electric power system. There are primarily three reasons why a fault can occur.
- Abnormal flow of electric current due to short circuit
- Sudden overshoot or dip of voltage
- Sudden overshoot or dip of the system frequency.
There might be some other issues that can lead to a faulty current in the system such as natural lightning fault or anomalies in the pole design, overhead cables, etc can take place. Therefore, we need to ensure that we can keep the fault isolated from the system so that the healthy portion of the system still works and provides us with electricity. We also got to learn the different types of faults that cause the system to malfunction. Firstly, overhead line faults are of six different types which are phase to phase fault, three-phase fault, single-phase earth fault, three-phase earth fault, open circuit fault, and cross-country fault. Next, we learned about the fault in the frequency whether the majority of the fault if it occurs, happens due to a single line to the ground fault which covers about 85% of the fault. The rest of the faults are line to line, double line to ground line to line to line faults. In the case of faults in transformers, it’s usually winding faults, core faults, tap changer faults, transformer accessories faults, and sustained or uncleared external faults where the majority are the winding and terminal faults.
There are three main reasons why we see fault.
- It is not economical to have a fault-free system
- Aging of insulations and contacts
- Geological impacts like weather and lightning.
This brings us to our next point, which is why do we need protection?
We need protection because of the following reasons.
- To detect anomalies by isolating that faulty part within the shortest period
- To prevent injury to personnel
- To prevent damage to the equipment
- To enable continuous service in the undamaged part of the network
Afterward, our speaker showed us a protective relay used in the protection system, its construction of it, and how it works. This allowed us to relate to the information he provided us. Furthermore, we learned about the protection items such as at station level, bay level, and process levels. We also got to know about protection relief device (PRD) operation.
Overall, we got to experience and gain knowledge that was fairly new to the audience and we are hopeful that our audience could gain some important information on power system protection and the identification of faults.