Kouga Wind Farm Project
The ACTOM group’s medium voltage switchgear business unit, ACTOM MV Switchgear, has frequently demonstrated its adaptability and technical capability of developing and producing cutting-edge equipment to best suit new applications as they arise.
Its development of a medium voltage compact substation for use in wind farm power generation is no exception.
Within a relatively short period it successfully developed and produced 36 kV compact substations – also known as pad-mounted transformer kiosks (PTK’s) – for use at the Kouga Wind Farm at Oyster Bay in the Eastern Cape.
The 80 MW Kouga Wind Farm, comprising 32 wind turbine generators (WTG’s), was completed late last year and is now operational. It was one of the major renewable energy projects in the “Window 1” first phase of South Africa’s national renewable energy programme launched two years ago.
ACTOM Power Systems, the group’s substation project management business unit, was awarded the R150-million electrical balance of plant contract for Kouga, comprising building a 33 kV/132 kV substation to link the wind farm to the Eskom power grid, providing and installing the 660 V/33 kV PTK’s at the bases of each of the WTG’s and installing the collector network linking them to the main substation.
ACTOM MV Switchgear was subcontracted to develop and produce the PTK’s, while ACTOM Power Transformers was assigned the task of designing and manufacturing the transformers for the PTK’s.
“The project was a new challenge for all three of us,” commented John McClure, ACTOM Power Systems’ General Manager.
“Being our first balance of plant contract for a wind farm, for our business unit it chiefly involved getting to grips with the complex grid compliance requirements, in addition to designing the cabling clusters in the collector network.”
The project posed unusual technical challenges for both ACTOM MV Switchgear and ACTOM Power Transformers, which had to develop substantially different forms of equipment in their respective fields than they had previously been called upon to devise for new applications. Furthermore, they had to achieve their respective goals within tight time constraints.
Greg Whyte, ACTOM MV Switchgear’s Design & Development Manager, explained: “With renewable energy, particularly wind farms, the transformer power and voltage ratings exceed the scope of traditional miniature substations, where the maximum power rating is 1000 kVA and the rated voltage is up to 24 kV. So for the Kouga project we were clearly venturing into unchartered territory, where the required rated power for the PTK’s was 2800 kVA and the rated voltage 36 kV.”
The main focus was on the MV compartment of the PTK, where the ring main unit had to meet the applicable internal arc classification (IAC) requirements and the compartment had to be suitable for housing two-, three- and four-function ring main units. “In addition, with the transformer having higher rated power than what we were used to, we had to design the low voltage assembly to ensure that the dynamic forces associated with the higher prospective fault level on the 660 V side of the transformer were taken into account,” Whyte said.
Among other requirements that had to be catered for in the design of the PTK was ensuring that it did not exceed the maximum allowable temperatures of the transformer and LV assembly, including provision of adequate ventilation.
The specially developed 2,8 MVA step-up transformers provided by ACTOM Power Transformers for the PTK’s are of stacked-core design, with mitre-cut joints and step lap construction.
“The LV windings were manufactured from continuously transposed conductors supplied by one of the world’s most advanced manufacturers of this equipment,” commented Ronnie Russell, ACTOM Power Transformers’ Divisional CEO.
“This type of winding is normally used in transformers of 10 MVA and above but were incorporated here due to the onerous loading requirements applicable to wind farm generator transformers.”
Said McClure of ACTOM Power Systems: “The ACTOM business units engaged on the Kouga Wind Farm project gained a great deal of valuable knowhow and experience in the process. It has been a steep learning curve for all of us, but it has equipped us well to tackle any such projects in the future with confidence.”
ACTOM (Pty) Ltd is the largest manufacturer, solution provider, repairer and distributor of electro-mechanical equipment in Africa, offering a winning and balanced combination of manufacturing, service, repairs, projects and distribution through its 40 distribution outlets throughout Southern Africa.
ACTOM is also a major local supplier of electrical equipment, services and balance of plant to the renewable energy projects.
It also holds numerous technology, distribution and value added reseller agreements with various partners, both locally and internationally.
For further information contact John McClure, ACTOM Power Systems
Private Bag 1, Bramley 2018
Tel (011) 430-8700 Fax (011) 887-9009
Press release compiled by Julian Kraft, J Kraft Public Relations
PO Box 2826 Wilropark 1731
Tel (011) 472-6686
Date: June 25, 2015.
Caption: A schematic drawing of the pad-mounted transformer kiosk (PTK) developed by ACTOM MV Switchgear for the Kouga Wind Farm’s wind turbine generators.