BPL Acting C.O.O. Ian D. Pratt on Load Shedding
By Khyle Parker
Jun 24, 2019 - 5:20:45 PM
NASSAU, NP: Load shedding is a measure employed by electric utilities when there is insufficient available capacity to meet customer demand. Failure by any power company to manage that supply/demand match could result in more widespread outages up to and including a total system collapse, as generators will eventually shutdown if they become overloaded. This is a built-in failsafe to prevent catastrophic engine damage. When there is an instance where the demand exceeds the supply, therefore, engineers in the BPL System Control Center implement load shedding to systematically reduce the demand in a controlled manner in order to prevent greater system challenges. The greater the level of generation shortfall, the greater the need to reduce the demand through any available means. At BPL, that means the implementation of several potential steps. These include shutting off buildings such as government buildings or commercial centers when they are not in use. Other potential steps include asking larger consumers such as hotels to reduce demand or switch in part or totally onto their generators. When necessary, it can mean switching off areas.
Over the past weekend and indeed since about the middle of last week, the loading – or demand – in New Providence exceeded the available supply, so load reduction measures had to be implemented. As per our earlier statement, increasing customer demand due to higher temperatures coupled with generation outages brought about the present situation. Last year, as you know, there was a fire at Clifton Pier which resulted in two of our largest engines being rendered inoperable. As part of our normal annual preparations in advance of the higher load period, additional generators were taken out of service for maintenance. Two of these units could not be returned as scheduled, given concerns identified during the maintenance works.
Despite these issues, we were still able for the most part to maintain power to New Providence. Last week however, additional generators at the Blue Hills Plant developed problems which resulted in them coming offline and setting up the present generation shortfall. The units were placed online later in the week but failed once again over the weekend. One of the units that was forced offline fed our heat recovery steam turbine. This unit requires the exhaust gases from the failed unit to heat its boiler and produce energy. Without the engine to provide the exhaust gases, the steam turbine also came offline. This caused a further capacity reduction. On Sunday afternoon, another generator – this time at the Clifton Pier Plant – tripped due to a mechanical problem. These issues caused a significant generation shortfall on Sunday and resulted in load shedding over and above normal load shedding exercises. The load shedding did not end until 1:50AM on Monday morning.
The engine at Clifton Pier was repaired and returned to service. The engines at Blue Hills were also returned to service albeit not at full capacity. The steam turbine was not restored since the output level required from its feed unit was not attained. In the short term, additional rental generation will be commissioned at the Blue Hills Plant to improve the available generating capacity, and reduce the need for load shedding. Work will also continue at Blue Hills in order to return the units to full output capacity and restore the steam turbine to service. It is projected that this work will take at least another week to ten days (following the arrival of needed spare parts). Finally, it is projected that works on the previously mentioned units that remain on maintenance related activity will be completed in mid to late July. This returned capacity will put our operations on a much stronger footing.
I echo the Chairman’s sentiment in expressing regret at the inability to meet our customers’ expectations over the last week. I also wish to thank the teams for working through the weekend to both repair the impacted units and return them to service, and to expedite the connection of the rental generation. Every effort to complete the needed repairs and return the remaining generators to service will be made.
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