The South African electricity transmission system faces the challenge of not only having to continuously keep up with the plans outlined in the Department of Energy’s (DoE’s) Integrated Resource Plan (IRP) 2010 but also having to ensure that there are reliable and stable power transmission networks to meet the country’s electricity supply demand, says State-owned power utility Eskom grid planning GM Mbulelo Kibido.
Speaking in January at a lecture organised by the South African national Energy Organi- sation on the ten-year Transmission Develop- ment Plan (TDP) 2013 to 2022, Kibido empha- sised the importance of providing a reliable electricity supply that would enable South Africa to meet its economic growth targets.
The IRP 2010 indicates that the DoE will implement two open-cycle gas-turbine (OCGT) power stations, which should be completed in time for the 2013 system peak in July. These power stations comprise two 147 MW units at the Dedisa substations, in Coega, in the Eastern Cape, and five 147 MW units at the Avon substation, in KwaZulu-Natal (KZN). These OCGT plants are being constructed for emergency backup purposes to avoid blackouts during the early morning and evening peak-demand periods.
The IRP 2010 also allows for the incorporation of independent power producer (IPP) coal-fired power stations under its new-build options. These power stations will use smaller units to match the IRP 2010 requirements, with two new IPPs in Witbank, Mpumalanga, and in Lephalale, Limpopo, having been allocated to produce 1 000 MW from 2019 to 2022.
“This requires significant capital investment, which is ultimately funded by electricity consumers through the electricity tariff. There is a need for stakeholders to understand the requirements of ensuring a reliable and secure supply. Improved reliability and a high-quality electricity supply need to be balanced against the cost of providing it to create optimal value for South Africa,” said Kibido during the lecture.
“Another challenge is ensuring that, while there are new projects in the pipeline, the transmission network is consistent and can support current projects so they are not jeopardised. Therefore, the transmission network’s expansion planning has to be undertaken to accommodate government’s expectations and the reliability and stability of projects under its wing,” said Eskom infrastructure investment planning manager Leslie Naidoo at the lecture.
The TDP indicates that total capital expen- diture for transmission, including expansion, refurbishment, spares, production equipment and land acquisition for the next ten years, is about R174-billion, of which R149-billion is budgeted for projects taking place in the next ten years. About R3-million is allocated to customer-related projects, R25-billion is assigned to generation integration projects and an estimated R121-billion is allocated to reliability projects.
National TDP Projects
The TDP schemes for Gauteng entail extending the 275 kV network, which was built to allow future upgrading, to a 400 kV insulation level, installing additional transformers at existing substations and constructing new substations.
The TDP scheme projects for KZN consist primarily of strengthening the 400 kV networks that transmit power to the Empangeni and Pinetown customer load network and introducing a 765 kV network. The 765 kV network will primarily be used for the transportation of power through the grid to the Cape.
Limpopo’s load growth is mainly because of platinum group metals and ferrochrome mining and processing activities in the province, states Eskom. The TDP scheme projects for Limpopo consist of extending the 400 kV and 275 kV networks, establishing a 765 kV network, integrating the Medupi coal-fired power station located in the province, and installing additional transformers at exist- ing and new substations in the province.
The TDP schemes for Mpumalanga consist of extending the 400 kV network, integrating the Kusile coal-fired power station currently under construction, and installing additional transformers at existing and new substations in the province.
Projects in the North West include the inte- gration of the 765 kV network required for the transfer of power from the Medupi power station and the integration of 400 kV to enable load growth in the local rural areas.
Projects for the Free State include the introduction of 400 kV lines and their transformation to support or relieve the 275 kV networks.
In the Northern Cape, projects comprise the introduction of 400 kV lines and their transformation to support or relieve the 400 kV and 275 kV networks. The integration of 1 100 MW of solar generation, in Upington, is also planned.
The TDP schemes for the Eastern Cape entail integrating the Department of Mineral Resources and the DoE’s OCGT power station at Dedisa; the reinforcement of the greater Port Elizabeth metro area, including the Coega industrial development zone; and the Greater East London strengthening scheme, which includes the integration of the Vuyani 400 kV/132 kV substation at Mthatha to supply the central and southern Transkei area.
Further, the TDP schemes for the Western Cape consist of extending the 400 kV network, introducing a 765 kV network and installing additional transformers at existing and new substations in the province.
“If the Nuclear 1 unit materialises at Thyspunt, in the Eastern Cape, three additional 400 kV lines will be required to link it to Grassridge and Dedisa, both in the Eastern Cape, using the new Port Elizabeth 400 kV/132 kV substation. The integration of Thyspunt has been excluded from this TDP, as it falls outside the planning period,” stated Eskom transmission group executive Mongezi Ntsokolo.
Meanwhile, the TDP studies forecast export to Namibia using the 400 kV and 220 kV inter- connections. The export amount is expected to remain constant over the TDP period.
“The overall TDP will result in the network becoming Grid Code compliant, which is the code that formulates the long-term strategic transmission corridor requirements, while catering for increased load growth and the integration of new generation. The TDP will run at a risk in some instances, given the limited funding for these projects, but careful operational mitigation planning will have to be employed until the transmission projects and new-generation builds are completed,” concluded Naidoo.