Challenges in Assessment of Transfer Capability Under a High Growth High Uncertainty Restructured Scenario in India

The role of the system operator worldwide as well as in India has undergone a great transformation over the last decade. From the role of ensuring that the bulk electric power system is operated in a reliable manner, the role has now got enlarged to ensure that the wholesale electricity markets also function efficiently. Each activity in system operation influences the electricity markets significantly, be it the planned or forced outage of an important transmission line leading to constraints in flow of power or outage of a power plant either due to a fault or fuel related issues.

Since 2003 when the new Electricity Act came into existence, there has been a paradigm shift in system planning and operation in the Indian power sector. Non-discriminatory open access to the transmission system has been a key part of the reform process. Therefore, assessment of transfer capability across different parts of the transmission network, broadcasting of this information for all the market players and updating it periodically becomes an important aspect of operational planning.

These developments have posed new challenges to the system operator and the transfer capability has to be determined in a precise manner. Unrealistic assumptions could either lead to sub-optimal utilization of the transmission system or necessitate real time curtailment to preserve the network security. Frequent curtailment of transactions in a large grid also has the potential for disputes as all market players have to be informed well before-the-fact. All this calls for a high level of transparency and availability of ‘common information’ to all market players. This paper deals with the challenges faced by the Indian system operator in this area, particularly considering the high level of growth as well as uncertainty in the restructured power system.

This paper describes the development of the electricity grids in India starting from regional grids. Initially, there were a few radial ties between the regions with power exchange taking place only in case of emergencies. From 1989–2002, HVDC back to back ties between the regions were also established paving the way for opportunity exchanges. Gradually, the regional grids were synchronized.

Non-discriminatory Open Access to transmission and development of electricity markets resulted in an explosion in electricity trading and bringing to centre stage, the issue of the network transfer capability. The physical limitations of the network had to be clearly informed to the market players. In a high pace of growth be it of load, new generating capacity or new transmission systems, a high level of uncertainty is inevitable. These uncertainties result in a situation where the congestion points move from corridor to corridor and necessitating the need for redefining the interface where Total Transfer Capability is declared. This paper highlights the above challenges for the Indian electricity grid and the manner in which it is being handled under regulatory oversight.