Andhra Pradesh Electricity Regulatory Commission (APERC) has released its forecasting, scheduling and Deviation settlement of solar and wind generation on 21/08/2017.

Executive Summary:

★ Applicability:

○ Regulation is effective from Aug 21st, 2017.

○ SLDC to issue detailed guidelines for QCA registration, scheduling procedures, communication protocols and formats etc., on or before Dec 1st, 2017.

○ Forecasting, Scheduling and Deviations Settlement shall commence from Jan 1st, 2018.

Further, generators commissioning on or after Jan 1st, 2018 shall not be allowed to be commissioned unless they start providing schedules as per this regulation.

○ Levy and collection of DSM Charges shall commence from Jul 1st, 2018

★ Regulation Applicable on: All the GRID Connected Wind and Solar Power Generators in AP.

★ Deviation Accounting:

★ Point of Forecasting: Pooling Station or STU/DISCOM Feeder where injection is made.

★ Virtual Pool: To enable benefits of larger geographical area and diversity, aggregation of forecast is permitted under “Virtual Pool” where Generators have an option to account for their deviations at an aggregated level through a Qualified Coordinating Agency (QCA).

○ A similar provision is also permitted in Karnataka by Hon. KERC in its final regulation which is already being implemented w.e.f 1st June 2017.


★ Role of a QCA:

○ Provide forecast, schedules and periodic revisions;

○ Coordination with DISCOM/STU/SLDC for metering, data collection, communication/issuance of dispatch/curtailment;

○ Commercial settlement of DSM charges and de-pooling of charges among generators;

○ All other ancillary and incidental matters.

★ Important differences between wind and solar power scheduling:

○ 16 revisions (excluding collective transactions) are permitted starting from 00:00 Hrs of the     day for Wind Generators

○ 9 revisions (excluding collective transactions) are permitted starting from 05:30 Hrs upto 19:00 Hrs of the day for Solar Generators

○ All the revisions are effective from the 4th time-block

○ Aggregation “seems” to be allowed between wind and solar generation as the concept of virtual pool aims to capture not only the larger geographical area but also the diversity (among different asset class).


★ Important differences between intrastate and interstate transactions:

○ Wind and Solar generators having common interface meter at a pooling station but carrying out both – interstate and intrastate transactions at the same pooling station, the scheduling for the same shall to be carried out separately.

○ Approved open-access capacity (in MW) in such cases alone shall be considered as AvC for the purpose of DSM charges calculations.

■ Observation: Since the regulation permits common interface meter for such transactions and AvC determination is also clarified, the DSM charges may be computed in pro-rata basis for such pooling station as the common interface meter would only provide Pooling Station level actual generation.


○ Further, aggregation is permitted only for similar type of transactions i.e., interstate transactions are not allowed to be aggregated with intrastate transactions for the purpose of DSM charges determination.

○ QCA shall separately settle DSM charges for intrastate and interstate transactions.

★ Determination of DSM Charges for INTRASTATE transactions:

Note: DX is the absolute error in kWh for a given error band starting from X% as outlined in column 2.

 ★ Determination of DSM Charges for INTERSTATE transactions: 

Note: DX is the absolute error in kWh for a given error band starting from X% as outlined in column 2.


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