The Tamil Nadu Electricity Regulatory Commission (TNERC) has issued the State Load Dispatch Center (SLDC) Functions and Accountability Regulations, 2026, mandating  renewable energy generating stations, nuclear power stations, and run-of-river hydro stations be treated as must-run stations and should not be curtailed except for grid security reasons.

The regulations seek to establish a transparent, accountable, and well-documented framework for the SLDC’s operations.

The regulations also apply to the SLDC but also to the State Transmission Utility (STU), intrastate transmission licensees, generating companies, distribution licensees, open-access customers, and all other entities whose scheduling, dispatch, metering, or grid operations are coordinated by the SLDC.

Operational Duties

The Commission emphasized that the STU will remain responsible for planning, strengthening, maintaining, and augmenting the transmission system, while the SLDC will be responsible for real-time operations, scheduling, dispatch, and grid security decisions.

The SLDC should monitor congestion in the intrastate transmission network and implement remedial measures.

The action on remedial measures initiated by the SLDC will be taken by the STU/distribution licensee.

The regulations also require the SLDC to implement a digital instruction module integrated with scheduling or SCADA/EMS systems.

Must-Run Status and Curtailment

Must-run generating stations, including renewable energy generating projects, nuclear power projects, and run-of-river hydro projects, should not be curtailed except for grid security reasons.The regulations distinguish renewable energy from battery energy storage systems. Renewable energy is treated as must-run, whereas battery energy storage systems are not and must be separately metered, scheduled, and accounted for.

The SLDC must maintain secure electronic records, including a master event log, curtailment and backing down log, instructions log, congestion log, transmission constraint log, disturbance and contingency log, and communication log. These logs must be time-synchronized and preserved for at least seven years.

For every curtailment event, the SLDC must record the dates and times of commencement and end, the identity of the affected entity, the schedule before curtailment, the actual permitted quantum, the exact reason for curtailment, the alternatives considered, restoration details, and the estimated energy curtailed.

Where must-run stations are affected, the SLDC must certify whether the curtailment was unavoidable for grid security and whether less restrictive alternatives were considered.

Planned curtailments must be communicated at least one day in advance, while emergency curtailments must be communicated as soon as possible.

Compliance Reporting

Also, the SLDC must publish monthly reports on its website within thirty days from the end of each month.

These reports must include the number and duration of curtailment events; entity-wise and category-wise curtailed quantum; corridor-wise congestion; voltage excursions; outages affecting scheduling or evacuation; directions issued to generators, storage systems, and distribution licensees; and curtailed energy separately for wind and solar.

The SLDC must also submit quarterly compliance reports to the Commission. The SLDC should implement the digital systems required to comply with these regulations, including automated logging, reporting, curtailment tracking, and digital reasoned instruction modules, within 18 months of the date of commencement of these regulations.

Post-Event Analysis

In cases involving large-scale curtailment, repeated backing down, islanding, a major voltage violation, prolonged congestion, or a system disturbance, the SLDC must conduct a post-event analysis within seven days.

The SLDC will not be held responsible for restrictions caused solely by transmission constraints, inadequate corridor capacity, transformer limitations, delayed system augmentation, or other infrastructural inadequacies, provided such causes are properly recorded.

The regulations also mandate that if a corridor, substation, line, transformer, reactive support element, communication channel, protection system, or control infrastructure repeatedly causes restrictions, the SLDC must record it separately, reflect it in monthly and quarterly reports, and issue a recurring-constraint notification to the STU.

Fees, Charges and ARR

The SLDC can recover its Aggregate Revenue Requirement (ARR) and associated charges in accordance with the applicable regulations on SLDC fees and charges. Until such regulations are issued, the Commission may determine the charges.

The charges may be recovered from state grid users through user-wise allocation, transaction-based charges, capacity or energy-based sharing, or a hybrid mechanism.

The regulations require the SLDC’s manpower strength to align with the Ministry of Power’s workforce guidelines for Load Dispatch Centers, with reference to approximately 144 personnel for a large SLDC such as Tamil Nadu.

Any cybersecurity incident that affects SLDC operations, telemetry, scheduling, dispatch, or data integrity must be reported to the Commission within 24 hours.

Failure by the SLDC to maintain logs, furnish event-wise reasons, comply with reporting obligations, or obey the Commission’s directions will be treated as a violation and may attract regulatory action.

Similarly, generating companies, distribution licensees, open access customers, and other grid users must provide the required data and comply with SLDC instructions. If they fail to do so, regulatory action will be taken.

An aggrieved entity may make a representation to the SLDC within five working days of the event, and the SLDC must respond within five working days based on records.

Recently, TNERC released draft regulations to determine tariffs for renewable and non-conventional energy projects for the control period from financial year 2028 to 2032.

Subscribe to Mercom’s real-time Regulatory Updates to stay informed about critical updates from the renewable industry.