The Appellate Tribunal for Electricity (APTEL) declined a wind power generator’s appeal against the Andhra Pradesh State Load Despatch Centre (APSLDC) and the Transmission Corporation of Andhra Pradesh (APTRANSCO), asking them to revise power curtailment instructions for wind projects connected to a substation in the state.

The appellant, Tata Power Renewable Energy Limited (TPREL), had filed an instant application seeking the Tribunal to direct APSLDC and APTRANSCO to revise its power curtailment schedule to evacuate 79.52% of the power generated from its 100 MW wind project. The wind projects were connected to the 400 kV Uravakonda substation and were curtailed to evacuate 67% of the power generated from the projects.

Tata Power argued that APTRANSCO had commissioned a 315 MVA interconnecting transformer (ICT)-4 at the substation instead of 500 MVA as initially planned. It alleged creating a bottleneck for the evacuation of power from renewable energy generators from a very early stage.

The appellant explained that as a result of the insufficient evacuation capacity at the Uravakonda substation, its Nimbagallu wind project was forced to run under conditions of curtailment enforced by the APTRANSCO and APSLDC. It added that between April 2017 and March 2019, it suffered a generation loss of 32.66 million units (MU), and consequently, a revenue loss of ₹174.4 million (~$2.4 million). Tata sought compensation for this from the APSLDC.

Following this, APTRASNCSO revised the curtailment percentage to 79.52% for all wind generators in its letter issued on May 14, 2019. However, in August 2019, APTRANSCO reduced the evacuation to 30.74% following some malfunction. But when the system was restored, the Andhra Pradesh Electricity Regulatory Commission (APERC) set the evacuation rates at 70%, which the appellants argued was an oversight on the part of the Commission. They argued that there was no reason for the APERC not to set the evacuation rate at 79.52%.

Tata Power further added that due to the curtailment, it would suffer losses to the tune of ₹86.6 million (~$1.2 million) over the next two months. It sought the Tribunal to revise the curtailment rate during the period of the appeal.

APSLDC and APTRANSCO, in their response, denied and disputed all the contentions made by Tata Power. They stated that the curtailment of power was done with their statutory obligations in mind and to maintain the safety and security of the grid. They stated that the APSLDC had taken all efforts to restore the transformers back into service.

The respondents explained that the reason they revised curtailment to 70% after the transformers were restored was that running them at 79.52% was the reason for the breakdown in the first place. They said that they were apprehensive of similar outages in the future, leading to more loss.

They noted that the 220 kV Borampalli-Kalyanadurg line was still under execution and that once the line is commissioned, it would be able to enhance its wind power evacuation capabilities. They said that the present arrangement of 70% evacuation would be in effect until the new line is commissioned.

In its final decision, the APTEL opined that given the circumstances at the Uravakonda substation, the 70% evacuation curtailment for wind power as decided by the state Commission in consultation with the APSLDC and APTRANSCO was justified. It said that even though the appellants will be unable to evacuate an additional 9% over the set evacuation limits, the security and the stability of the grid cannot be compromised. It noted that if the transformers were to malfunction in the future as a result of a higher evacuation rate, other wind generators connected to the substation would suffer additional generation and financial losses.

“We are not inclined to interfere with the optimum scheduling and despatch (70%) decided by the state Commission and respondents,” the APTEL said in its final order.

Solar power curtailment has been mired in controversy in Karnataka, Telangana, Punjab, and Andhra Pradesh. Solar developers in these states have already sought state regulatory commissions and court intervention. Solar developers have sought transparency in grid curtailment issues.

Recently, Wardha Solar and Parampujya Solar submitted a petition asking to ensure the ‘must-run’ status of renewable projects in Karnataka. Both these special solar power vehicles belong to Adani Solar. They had also requested the Central Electricity Regulatory Commission to direct Karnataka to stop issuing directions to back down power from these solar projects.