Electricity is the basis on which civilization thrives. We can’t even imagine a world just about 100 years ago which was devoid of electricity. Every development in the past century has been made possible due to power. We have reached a stage where power is a given. Now, the competition is on the quality of electricity.
Competition in power supply segment is going to be based on the following parameters:
3. Customer expectations (Quality)
Reliability indices based on the following parameters:
1. Outage duration
2. Frequency of outages
3. System availability
4. Response time
Although the terms power quality and system reliability seem the same, they aren’t. System reliability pertains to sustained interruptions and momentary interruptions. Power quality involves voltage fluctuations, abnormal waveforms, and harmonic distortions. An interruption of greater than five minutes is generally considered a reliability issue, and interruptions of less than five minutes are a power quality concern.
The Institute of Electrical and Electronic Engineers (IEEE) define the generally reliability indices in its’ standard number P1366, “Guide for Electric Distribution Reliability Indices”. Some of the several important definitions for reliability including what are momentary interruptions, momentary interruption events, and sustained interruptions. –
Momentary interruption :- A single operation of an interrupting device that results in a voltage zero.
Momentary Interruption Event :- An interruption of duration limited to the period required to restore service by an interrupting device. This must be completed within five minutes.
Sustained interruption:- Any interruption not classified as a momentary event.
The most common distribution indices include:
• System Average Interruption Frequency Index (SAIFI)
• System Average Interruption Duration Index (SAIDI)
• Customer Average Interruption Duration Index (CAIDI)
• Momentary Average Interruption Frequency Index (MAIFI)
• Customer Average Interruption Frequency Index (CAI)
• Customers Interrupted per Interruption Index (CIII)
• Average Service Availability Index (ASAI).
These indices in determining the quality of the power supplied. The pricing and the maintenance can be determined on the basis of this. Since, we are moving towards a market based economy in the power sector, these determining indices help in segregating the players in the market.
Reliability Improvement Strategy has to be developed for each utilities depending upon their requirements. Outage mitigation technique in distribution system is require to be adopted in order to improve the reliability of the system. Reliability assessment of distribution infrastructure based reliability metrics to be computed in line with the field data gathered for a study period.