Sri Lanka’s energy regulator, the Public Utilities Commission of Sri Lanka (PUCSL) has identified a number of failures on the part of the Ceylon Electricity Board (CEB) for the repeated island wide blackouts occurred since last year and has asked the latter to inform of the actions taken to prevent a repetition of such incidences. In a joint study carried out by the PUCSL with the assistance of a Canada-based power sector consultancy on the island wide blackout occurred on September 27, 2015 has identified some of the practices by the CEB as “risky” and gave both short and long-term strategies to be adopted by the national power supplier immediately.
The Commission also said that single element failure in the power system should not result in island wide power failures and thus the CEB had violated the transmission license entered into with the regulator.
“It the responsibility of the transmission licensee (CEB) under condition 30 of the transmission license to maintain an uninterrupted power supply throughout the country, which has been violated three times in the last 6 months by way of islandwide power failures,” PUCSL Chairman, Saliya Mathew said in a letter to the CEB General Manager, M.C Wickramasekara sent last week. In a bizarre turn of events, the entire country was left in dark without power in three instances – on September 27, 2015, February 25, 2016 and March 13 – with the final occurrence being the worst and the longest blackout in 20 years.
Meanwhile CEB Additional General Manager Bandula Thilakasena was reported to have told a public forum organized by the PUCSL on consumer rights last week that it was difficult for them to maintain uninterrupted power supply even in urban areas including Colombo and suburbs due to tighter restrictions in laying high tension power lines above urban areas.
Among other shortcomings the PUCSL and the Canada-based Manitoba HVDC research centre identified the CEB’s practice of allowing plus or minus 10 percent tolerance for voltage control in 132kV and 220kV lines to be, “risky considering this limit is very close to overcurrent protection limit of many system devices”.
The international practice stands at plus or minus 5 percent. Further the joint study said the dynamic transmission system model used by the CEB transmission planning and system control branches are not accurate enough for dynamic response analysis and the model data need to be verified with field tests for system elements along with accurate modeling of loads. “Based on the reactive power limits used by CEB for modeling the network, system control centre does not utilize the full reactive power capability of the generators connected to the network,” the PUCSL said, highlighting another shortcoming. The PUCSL directed the CEB to design long-term measures to avoid such system failures in future.