With an ambitious target of 175 GW of renewable power by 2022, the need for reliable and flexible power generation has been reiterated time and again by policymakers, planners and regulators. Given the country’s huge hydropower potential of about 150 GW, hydroelectric projects (HEPs) can play a key role in facilitating renewable power integration, owing to features such as overload capacity, fast ramping, peaking support, black-start capability, dynamic VAR support and multiple start-stop operations. However, hydropower growth and its optimised operation face several regulatory, technical and financial constraints.
In this context, the Forum of Load Despatch (FOLD) Centre constituted a working group on hydro to study the existing hydropower capabilities, tariff design, operating norms and constraints, flexibility indices, scheduling practices, integrated operations of hydro stations sharing a common basin, pumped storage and communication facilities. The group carried out a survey of 149 HEPs (aggregating 35 GW of capacity), accounting for 80 per cent of the total installed capacity in the country. Big data analytics was carried out on hydropower data for the past eight years, along with a pattern analysis and other tools. FOLD and Power System Operation Corporation Limited brought out a report on the Operational Analysis for Optimisation of Hydro Resources and Facilitating Renewable Integration in India in July 2017. Power Line presents the key findings and recommendations of the report…
Key findings
As of April 2017, the country’s renewable energy generation capacity stood at 57 GW, while the available hydro resources for managing the associated variability and intermittency stood at 44.6 GW. As per the working group, the hydropower penetration level at the national level stands at 14 per cent of the aggregate installed capacity. This indicates the need for better optimisation of the existing hydro resources at the regional as well as the national level.
HEPs, especially at storage type and pumped storage type stations, are capable of providing peaking service. However, the peaking power available from HEPs at the all-India level stood at 70 per cent (32 GW) of the installed capacity due to the lack of incentive schemes and a market mechanism. Further, a number of hydro stations have a single-part tariff structure that recovers the cost based on the design energy.
An analysis of hydro generation data between 2007 and 2016 showed that under overflowing hydro conditions between June and August, hydro provides minimal peaking support (of the order of 4-6 GW) as most of the hydropower stations operate as baseload. Meanwhile, during November to February, hydro provides up to 8-10 GW peaking support, with a ramp rate of 50-60 MW per minute. Further, it was observed that flexibility is higher in the lean hydro season and less in the high hydro monsoon season, which is more prominent for the northern, eastern and north-eastern regions. Also, the flexing of hydro generation has improved from 2014 onwards at the all-India level.
Recommendations
The working group provides several recommendations for facilitating the optimisation of hydro resources. First, the state commissions need to incentivise peaking availability in the tariff regulations to encourage peaking support from HEPs. Also, state-owned hydro resources should optimise operations while factoring in the price curves obtained from the day-ahead markets to achieve a higher all-India hydro peaking availability. The optimisation results indicate the possibility of additional peaking from hydro by 4,200 MW while off-peak hydro generation could be reduced by 5,000 MW at the all-India level, which would result in a net monetary gain of Rs 26 million per day.
The working group suggests moving from 15-minute scheduling to 5-minute scheduling, which would provide strong signals for fast ramping. Also, hydropower projects with pumped storage capability need to be operationalised soon to ensure better utilisation of such projects for power generation and flexibility. Further, enabling regulations need to be issued by the state regulatory commissions to include intra-state hydro units under the framework of Reserves Regulation Ancillary Services. The associated transmission system limits the flexibility of hydropower stations. Thus, transmission planning studies must factor in simultaneous operation of all the hydropower plants evacuating power on the same high capacity transmission corridor. The working group recommends the creation of a robust communication infrastructure for the flow of real-time telemetered data from the HEPs to load despatch centres, provision for a multi-part tariff structure for hydro generation and following a coordinated approach for hydro despatch and scheduling.
The implementation of these recommendations will go a long way in removing the constraints in integrating renewables with the grid, going forward.
