Huge variations in renewable power availability make grid-handling hard in Andhra Pradesh

VIJAYAWADA: With drastic changes in the availability of the variable renewable energy (VRE), the Andhra Pradesh State Load Despatch Centre (APSLDC) has written to the Andhra Pradesh Electricity Regulatory Commission (APERC) inferring that “major discrepancies” are making it difficult to handle the grid. The SLDC also said that the differences/changes in the forecast and actual availability were not being predicted by the VRE generators.

Citing the proceedings on April 24 when solar generation fell from 1,650 megawatts (MW) to 1,075 MW and then to 575 MW, the SLDC explained that such drastic fall has resulted in overdrawl from southern region (SR) grid. “Solar generation had drastically fallen at 13:45 hrs (on April 24) from 1,650 MW to 1,075 MW, causing overdrawls from the grid beyond permissible limits. In order to avoid the load shedding at this juncture, the APSLDC immediately acted and claimed for un-requisitioned surplus (URS) power,” the letter stated. 

It further said the Southern Region Load Despatch Centre (SRLDC) cautioned the APSLDC to curtail the overdrawl. “At 15.45 hrs, the solar generation had further drastically fallen from 1,075 MW to 575 MW, which resulted in overdrawl again from SR grid and SRLDC had issued notices to the SLDC,” the SLDC informed. Later in the day, the solar generation raised by 140 MW and wind generation also shot up, resulting in under-drawl from SR grid beyond Indian Electricity Grid Code (IEGC) limits. Again, SRLDC had issued notices to curtail the generation,” the officials said in the letter.

“It is difficult to handle the grid when there is huge variation in the forecast and actual availability. This has become a regular phenomenon and the VRE generators or the qualified coordinating agencies (QCAs) can’t provide forecast on these variations on a day-ahead basis,” a senior official explained. For the record, the Transmission Corporation of Andhra Pradesh (APTRANSCO) has already proposed amendments to the regulation 4 of 2017 issued by the APERC for forecasting, scheduling and deviation settlement of solar and wind generators for levying deviation charges from qualified coordinating agencies.

It said that the state grid was being operated in the range of 5,300 MW to 10,170 MW on real time basis with a mix of RE generation of installed capacity 7,500 MW. It had previously told the commission that large scale variations ranging between 50MW and 2,000 MW were forcing the state to either shed the load or purchase high-priced power on the spot at a short notice. The APERC has invited views of the stakeholders, most of whom opposed the argument of the State.