Islamabad            -           The Overall performance of NTDC has improved in 2017-18 except the system security of NTDC that was deteriorated as the total Energy Not Served (ENS) in the year was 525.5 percent higher over the previous year and has financial impact of around Rs2,486 million. In Performance Evaluation Report of 2017-18 for NTDC and K-Electric, National Electric Power Regulatory Authority (NEPRA) however said that the System duration of interruption by NTDC was decreased by 44.4 percent as compared to preceding year.  System duration of interruption is a reliability indicator that measures the average outage duration that an interconnection point observes in a year. As per Performance Evaluation Report of 2017-18 the interruption witnessed in NTDC was around 0.6 hours (36 minutes) on average that indicates a decrease of 44.4% as compared to preceding year’s average of 1.08 hours (1 hour & 5 minutes).

In order to gauge system security, the estimates of total Energy Not Served (ENS) during the year as reported by the licensee has been analyzed. The total ENS as reported by NTDC in 2017-18 is 469 million kWh that is 525.5% higher over the previous year i.e. 74.981 million kWh. Based on the average energy sale rate of DISCOs, the financial impact amounts to around Rs2,486 million. During 2017-18 the average number of outages per circuit for NTDC turn out to be 0.29, showing a decrease of 17% over the previous year i.e. 0.35. System frequency of interruption is a reliability parameter that measures the average number of outages per circuit in a year. During year 2017-18, number of voltage violations for NTDC remained 149,754 that indicate 42.7% increase as compared to 104,924 violations in preceding year. The highest voltage recorded due to voltage variations at 500 kV voltage class was 575 kV for time duration of 60 minutes, recorded at D. G. Khan. The voltage of 575 kV shows approximately 9.5% variation with respect to allowed limit (±5% = 525/475 kV). Similarly, at 220 kV level, highest voltage was 254 kV recorded at Loralai for time duration of 300 minutes. Voltage of 254 kV indicates approximately 10% variation with respect to allowed limit (±5% = 231/209 kV). 

During the reported period, NTDC system frequency varied from 50.51 Hertz to 50.62 Hertz and has violated the prescribed limits 25 times, however, it has shown improvement in comparison to the preceding year. Out of 189, a total of 103 power transformers remained loaded more than the prescribed limit of 80% in the month of June, 2018. These include nineteen (19) 500/220 kV transformers and eighty four (84) 220/132 kV transformers.