National Electric Power Regulatory Authority (Nepra) has certified that performance of Karachi Electric (KE) and National Transmission and Despatch Company (NTDC) improved in 2019-20 with respect to preceding year.
Nepra, in its Performance Evaluation Report (PER) of KE 2019-20, said that system duration of interruption was witnessed on average around 0.12 hours (7 minutes) which shows a decrease of 80% as compared to preceding year’s average of 0.61 hours (37 minutes).
Regarding system frequency of interruption, it was observed that average number of outages per circuit for KE remained 0.09, showing a decrease of 77% over the previous year i.e. 0.39.
Performance improved with respect to preceding year as the reliability and quality of supply indicators have shown a considerable boost.
In order to gauge system security, the estimates of total ENS (energy not served) during the year as reported by the licensee were analyzed. The total ENS as reported by KE is 0.701 million kWh that is 74% lower than the previous year i.e. 2.678 million kWh; based on the average energy sale rate of KE, the financial impact amounts to around Rs. 6.7 million. KE has reported 3 incidents of loss of supply during the year 2019-20 which translates into total duration of 0.95 hours.
KE’s voltage violations remained the same i.e. 9 in 2019-20 as compared to preceding year. Further, no violation occurred at 220 kV level both under normal and N-1 conditions and at 132 kV level, limits were violated under normal conditions.
The data submitted by KE was analyzed and it was revealed that frequency remained within the prescribed limits. Nepra further noted a significant improvement by NTDC in reliability and security indicators during the year 2019-20 as compared to preceding year. However, voltage violations and low voltage profile is still a question mark and NTDC needs to improve its functions of planning, operation, protection, augmentation & expansions and rehabilitation to overcome these issues.
In order to diagnose the root cause of low voltage, monitoring activities are being initiated by Nepra on periodic basis to avoid any undesirable condition on the system and ensure continuity and stability of supply to the electricity consumers.
Nepra has prescribed limits for frequency variations under the Rules. During the reported period, NTDC has violated the prescribed limits 9 times which shows improvement in comparison to the preceding year.
On the lower side, the voltage remained as low as 171 kV that indicates 18.2% variation with respect to allowed limit (±5% = 231/209 kV) which may affect the consumer end voltages and consequently equipment damage.
The highest voltage recorded due to voltage variations at 500 kV voltage class was 565 kV for time duration of 60 minutes, recorded at D. G. Khan. The voltage of 565 kV shows approximately 7.6% variation with respect to allowed limit (±5% = 525/475 kV).
Similarly, at 220 kV level, highest voltage was 250 kV recorded at Sibbi, Loralai and Dharki for time duration of 60 minutes and 120 minutes respectively. Voltage of 250 kV indicates approximately 8.2% variation with respect to allowed limit (±5% = 231/209 kV).
