HVDC East-South interconnector II in India: 2000 MW, +/-500 kV

The world-wide electrical power consumption is projected to increase by over 70% during the next two decades. India is expected to enhance its electricity consumption at a rate of about 5% annually. That means enormous investments in power generation as well as in building up an interconnected national power grid. For an optimum utilisation of the electrical power available in the regional grids, they must be interconnected with each other by inter-regional lines. Particularly, the surplus energy available in one grid could then make up for the deficit in another, caused there e.g. by seasonal fluctuations in the availability of hydro-power in winter, or by major system breakdowns. The traditional AC power transmission technology with extra high voltages comes to its limits however, when asynchronous networks are to be interconnected with each other, or when the transmission distance is long. System stability problems may occur with AC interconnections in such cases. In India there are presently six HVDC systems in operation which have contributed considerably to the linking of its dissimilar regional grids. In March 2000, Powergrid, the largest power transmission utility of India, awarded a new long distance HVDC transmission project to Siemens Germany. This project is being executed now. The HVDC system 'East-South' will transmit 2,000 MW of electrical energy from the power generation centre in Talcher in the State of Orissa -over a distance of about 1,400 km - to Bangalore in the State of Karnataka, a rapidly developing industrial high-tech area that needs this bulk power urgently to cope up with its increasing electricity demand. The present paper highlights some key aspects of this mega project starting from design considerations for all vital-components including converter valves, converter transformers and a state-of-the-art control and protection system. Furthermore, the paper introduces the design and performance criteria for the transmission system.