Forecasting is a key tool supporting the flexible operation of a power system and in India it is especially important as the country is adding hundreds of megawatts of variable renewable energy generated from wind and solar power plants.
The government of India has set an ambitious target of having 175 GW renewable energy capacity by March 2022, including 100 GW of solar parks and smaller systems, 60 GW wind, 5 GW small hydro and 10 GW bioenergy. Given that most of the capacity will come from intermittent energy sources, its integration into the national grid would pose technical, commercial and regulatory challenges for generators and grid operators.
India has to find ways to deal with the variability of wind and solar output and the certain level of uncertainty associated with it.
India's grid is already weak, experiencing high line losses, load shedding, low voltages at the distribution tail end, high variation in frequency, and lack of adequate reserves, flexible generation and effective demand forecasting. This makes the reliable and effective grid integration of renewables even more challenging. Hence, policy-regulatory officials and grid operators fear that a steep and rapid increase in "infirm" or "non-dispatchable" renewables will affect the electricity grid and make grid operation far more complex and difficult to deal with.
One key tool supporting the flexible operation of the power system is forecasting.
Flexibility is one of the most important characteristics a power system needs to possess in order to integrate variable renewable energy generation. Flexibility can be defined as the ability of a system to adapt to changes in load and generation at any time scale. Forecasts of renewable power generation have always been of utmost importance for achieving that.
This is especially true of wind power, where accurate forecasting reduces the risk of uncertainty and allows for better grid planning and integration of wind into power system. Policymakers have been working on improving the regulatory framework for forecasting and scheduling in India.
The Forum of Regulators (FOR) have put forward a model regulation on Forecasting, Scheduling and Imbalance Handling of the Renewable Energy plants. This regulation is in line with the CERC framework on forecasting and scheduling. Based on the model regulation by FOR and the CERC framework almost all of the Indian wind-rich states have come up with their own regulations on forecasting, scheduling and a deviation settlement mechanism.
The table shows a comparison of forecasting and scheduling regulation.
Key Definitions and Interpretations of Forecasting & Scheduling Regulations are:
- Time-Block: means a time block of fifteen (15) minutes, for which specified electrical parameters and quantities are recorded by special energy meter, starting from 00:00hrs.
- Deviation: in a time-block for a seller means its total actual injection minus, its total scheduled generation.
- Available Capacity or AvC: means for a wind/solar generating station the cumulative capacity rating of wind turbines that are capable of generating power in a given time-block and for a solar generating station the cumulative capacity rating of solar inverters that are capable of inverting power in a given time-block.
- Absolute Error: means the absolute value of the error in the actual injection of wind and solar generators with reference to the scheduled generation and the ‘Available Capacity’ (AvC), as calculated using the following formula for each fifteen (15) minute time block:
Absolute Error (%) = 100X [Actual Injection-Scheduled Generation]/(Avc);
- Schedule: Every wind and solar generator shall submit a day-ahead and week-ahead schedule of each generating station or each pooling stations at the fifteen minutes time-block (96 time blocks for the day). Revision of schedule may vary as per the state regulations.
About the author:
The author of this article, Angad Gupta, currently works as an analyst in 3Tier R&D India Pvt Ltd. He has seven years of experience in renewable energy. Angad specialises in Forecasting & Scheduling, SCADA and wind assessment.
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Forecasting & scheduling regulation status in India.
