adminwith a problem at Kariba South that then caused the Hwange Power Station to automatically shut down to avoid overload.
While Kariba South was quickly brought back on line, a rapid process since it is a hydro station, the restoration of all units at Hwange Thermal Power Station was still in progress late yesterday with the first unit only expected back on the grid in the evening.
This was why there was extensive load shedding yesterday as Zesa battled to supply the most critical consumers using Kariba South power and imports alone.
Zesa spokesperson Mr Fullard Gwasira yesterday said the disturbance at Kariba had forced the Hwange Power Station to trip due to overload.
“Hwange Power Station was overloaded as a result and it tripped to protect itself. At some point we lost both Hwange and Kariba.”
Zesa quickly brought back the six Kariba units, with some Harare suburbs getting power just over an hour after the problem occurred.
By 11pm all Kariba units were back on the grid, allowing Zesa to switch efforts to the slow restoration of Hwange.
Bringing a thermal station back onto the grid involves restarting boilers and only once steam in a unit has been raised then synchronising the output to match the grid precisely, a far longer process than doing the same at a hydro station.
“We expect the first unit to be online this (Thursday) evening while the other ones will be done the following days because we are syncronising them in phases.
“It takes time to bring the station back online, it’s different from hydro because we need to heat it first before it can generate electricity,” he said.
Mr Gwasira said because of the severe loss of generation capacity, load shedding was going to be done outside the schedule.
“At Kariba we are currently generating 615 megawatts, Bulawayo at 24MW while 160MW are imports. Our usual generation capacity is 1 400MW.
“This means that load shedding will correspondingly be higher at the moment and customers will experience load shedding outside the schedule,” Mr Gwasira said.
Hwange can generate at its present stage of rehabilitation around 780MW if all six units are working.
The system disturbance at Kariba on Wednesday hit Harare, Gweru, Chinhoyi, Masvingo and Beitbridge.
Zimbabwe has already opened tenders for the expansion of Kariba and Hwange power stations.
The Zimbabwe Electricity Transmission and Distribution Company, a subsidiary of Zesa, recently said that Zimbabwe would continue to have serious load shedding and power outages until 2014, as the power utility is struggling to raise US$125 million needed to repair the outdated Hwange Power Station, which when fully renovated generates 920MW.
Online Reporter