CERC Rejects TANGEDCO’s Plea For Detailed Power Drawal Data In ISTS Charges Dispute

The Central Electricity Regulatory Commission (CERC) has passed an order on an interlocutory application filed by Tamil Nadu Generation and Distribution Corporation Limited (TANGEDCO), seeking directions against the Grid Controller of India Limited (Grid-India) for providing detailed power drawal data. The application was linked to an ongoing dispute over the calculation of Inter-State Transmission System (ISTS) charges and transmission losses applicable to Tamil Nadu.

TANGEDCO’s concern arises from the implementation of the CERC Sharing Regulations, 2020. As per these regulations, when a power generating station is connected to both the inter-state grid and the intra-state, or state-owned, transmission network, ISTS charges should be applied only to the portion of capacity that is actually connected to the inter-state system. TANGEDCO argued that in the case of several generating stations, including NLC TPS II Stage II, NTECL Vallur, NTPL, and a portion of the Kudankulam Nuclear Power Project, power is mainly drawn through the Tamil Nadu state transmission network operated by TANTRANSCO, rather than through the inter-state grid.

Based on this argument, TANGEDCO claimed that the power drawn through the state network should not be counted as Long-Term Access (LTA) for the purpose of calculating ISTS charges. According to the utility, the implementing agencies wrongly treated such power drawal as “deemed LTA,” which resulted in higher transmission charges being imposed on the state. TANGEDCO maintained that this has created an additional and unfair financial burden on electricity consumers in Tamil Nadu.

To support its claims, TANGEDCO requested detailed node-wise and block-wise power drawal data from Inter-State Generating Stations for the period from 2018–19 to 2023–24. The utility stated that this data was necessary to show actual usage patterns and to prove that power was largely being evacuated through the state network rather than the inter-state system.

During the proceedings, the Central Transmission Utility of India Limited (CTUIL) submitted some information related to power allocations for the relevant period. However, TANGEDCO argued that the data provided was not detailed enough to properly assess its claims and was insufficient for deciding the main petition.

While examining the interlocutory application, the Commission referred to the work of a sub-group formed under the Southern Regional Power Committee (SRPC). This sub-group had developed a methodology to assess whether a state’s transmission network is capable of evacuating its share of power without relying on the inter-state grid. Using this methodology, exemptions from ISTS charges had already been granted for certain generating stations, including Madras Atomic Power Station (MAPS) and NLC TPS II Stage I.

After reviewing the matter, CERC concluded that the block-wise drawal data sought by TANGEDCO was not relevant for deciding the key legal and regulatory questions involved in the main petition. The Commission observed that TANGEDCO had not clearly explained how the requested data would affect the determination of LTA under the 2020 regulations. It also noted that seeking similar data related to other states was not relevant to the case.

As a result, the Commission rejected the prayers made in the interlocutory application. However, it clarified that the main petition filed by TANGEDCO, which seeks a revision of transmission charges, will continue to be examined separately.