Power grid main characteristics
Eskom is a state-owned electricity utility that supplies approximately 95% of South Africa’s electricity and more than 40% of Africa’s electricity. The utility is vertically integrated and is responsible for generation, transmission and distribution. Eskom also trades electricity with Southern African Developing Countries (SADC) in the African region. Electricity is predominantly generated from coal with nuclear, gas, hydro, solar and wind forming a smaller portion of generation. The SA grid is the largest in Africa and is interconnected to parts of the SADC countries primarily Mozambique, Botswana and Namibia.
The SA network is one thousand four hundred kiliometers (1400km) long. For illustrative purposes if it were to be superimposed on a European map, the grid would stretch from Gibraltar to Brussels.
The country has 28 000km (twenty-eight thousand kilometers) of transmission lines and 160 substations across the country
South Africa’s transmission meshed network increases reliability of supply and has been designed for n-1 redundancy.
High voltages include 132kv, 275kv, 400kv up to 765kv
The network is divided into nine geographical grids along provincial boundries.
The grid has been designed to transport electricity from coal-fired power stations situated predominantly in the east of the country (Mpumalanga Province) to the rest of South Africa.
South Africa is connected via two 765kv DC lines to its African neighbours – connecting Mozambique with South Africa. South Africa imports 1500MW from Mozambique. Eskom also wheels power to other SADC countries for Mozambique. lf.
Major incidents and preventive measures
Eskom initiated national load curtailment (load shedding) in 2008 due to a national capacity constraint. Load shedding was initiated as a measure to protect the national grid from a total country blackout. Additional issues of bad weather conditions, coal availability and deteriorating generation plant performance culminated in this perfect storm during that period. While the power system still remains significantly tight, the company has not load shed since April 2008. Eskom has indicated to South Africans that the system will remain tight until more capacity is added to the power system.
The utility has introduced supply-side and demand-side solutions to manage the short to medium-term risks. On the supply side, Eskom has increased capacity by 3 720 MW by returning previously de-mothballed power stations. Currently, Eskom is undertaking the biggest capital expansion programme in the country and an additional 10 916MW is planned to come on-line predominantly from new coal-fired power stations (Medup and Kusile) and a pump-storage (Ingula) power station. Medupi’s first unit is expected to come on-line in 2014.
On the demand-side, Eskom has introduced demand-side management and demand response solutions. Demand response solutions include power-buy backs and demand market participation with key industrial customers. DSM initiatives include retrofitting homes and business with energy saving technology and introducing consumer incentives such as solar water geysers (water heating system) and heat pump installations, as alternatives to heating with electricity. Eskom has launched a marketing initiative called 49M to drive the importance of energy efficiency and to encourage a change in behaviour.
Severe snow falls in the Kwa-Zulu Natal province, resulted in pro-longed power outages in October 2012. Towers in the areas have been redesigned to manage the impact of change in weather conditions in the country.