India’s renewable energy capacity soars to 178 GW

Ongoing efforts are underway to tackle integration challenges in the clean energy sector.

As of September 2023, India has reached a renewable energy capacity of 178 GW. This includes 71 GW of solar power, 51 GW of Hydro, 44 GW of Wind and other renewable sources. The country plans to achieve 500 GW of non-fossil fuel based energy capacity by 2030. The likely installed capacity in 2030 is 293 GW of solar, 99 GW of wind, 59GW of Hydro, 15 GW of biomass, 41 GW of battery energy, and 19 GW of pump storage. Ongoing efforts are underway to tackle integration challenges in the renewable energy sector.

Variability and intermittency

Power generation from renewable sources like wind and solar is variable and intermittent. Large penetration of these resources in the electricity grid may pose threat to grid stability and security. Robust forecasting techniques, scheduling, and proper balancing mechanisms will help the grid operators manage the variability effectively. Renewable energy management centres were established at 11 locations for better RE forecasting at SLDC/RLDC and NLDC. Provisions for scheduling for RE generation are mandated in the grid code.

Resource adequacy

At present, the contribution of thermal generation is significant in meeting peak demand. Conventional power plants must be operational to supply electricity during periods without sunlight. The all-India peak demand is observed to be increasing year on year. The time of occurrence of peak demand and peak RE generation are at different times. This scenario is leading to resource adequacy shortfall at times. Ensuring resource adequacy at all time frames is of utmost importance. Conventional generation growth will be limited, with an increasing reliance on renewable energy sources. Grid code now requires resource adequacy measures to ensure reliability.

Flexibility

The gap between the highest and lowest All India electricity demands has been consistently growing. This trend, combined with a surge in solar power, is causing an increase in the “Duck Curve” belly. Additionally, the accuracy of renewable energy and load forecasts significantly influences the need for flexibility. To address this, sufficient flexible resources like fast ramping power sources, lowered minimum operation levels for conventional plants, quicker start-up and shutdown capabilities, reduced uptime/downtime, and adopting two-shift operations are essential.

System inertia

The increasing use of non-synchronous renewable energy sources diminishes system inertia, leading to issues with transient stability and elevated RoCoF (Rate of Change of Frequency). To tackle this challenge, planning standards are exploring the incorporation of synchronous condenser facilities. This can be achieved through either new construction or retrofitting. Standards for synthetic inertia and fast frequency response from inverter-based generation sources are also explored.

Reactive power management

Significant voltage fluctuations are noticed near renewable energy stations. High voltages occur during low power generation and nighttime, while low voltages happen during peak RE periods. Dynamic VARs from inverter-based resources (IBR), including night mode of PV inverters and wind turbine generators (WTGs), is used in a limited way and futher oppurtunities are under review. It is crucial to consider synchronous condensers, STATCOMs, and other support technologies during the planning stage. Grid code mandates the provision for reactive energy payment and penalties.

Robust transmission network and grid resiliency

The increasing penetration of renewable generation has resulted in a behavioural change in the interregional flow patterns across the country. To accustom to this change, there is a need for adequate flexible transmission resources such as high-voltage direct current transmission links in the grid. Transmission planning to factor 8760 hrs flow pattern is the need of the hour. Further, timely commissioning of the transmission elements identified in the transmission system for integrating over 500 GW RE capacity by 2030 and other transmission plans needs to be ensured.

Short circuit ratio / Low fault levels and oscillations

The fault levels / short circuit ratio was observed to be low at some pooling stations due to weak connectivity and during the forced outage of the critical transmission corridor. The low fault level (short circuit ratio) at the RE pooling station leads to stability issues (oscillations) in the system. There is a need for planning and implementing countermeasures for future grids by regular assessment of the grid strength. Synchronous condenser / STATCOM and other supporting technologies at the planning stage are being explored.

Modelling, simulation and field testing

With the rapid integration of renewables into the grid, the importance of accurate modelling and simulation capabilities is also growing significantly. Modelling and simulation studies not only aid in renewable energy compliance verification and interconnection planning but also in understanding and addressing the complexities arising from the integrated operation of large quantum of renewables in close vicinity. Furthermore, it is important to develop lab/ field test facilities for testing inverters and wind turbines against specified standards in India.

Protection-related issues

Frequent undesired tripping of renewable energy generation results from inverter protections, feeder protection settings, coordination issues, and noncompliance with technical standards like LVRT and HVRT. Addressing these problems requires stringent regulatory measures and enforcement of the same.

Regulatory provisions

The regulatory landscape in the power sector, including IEGC 2023, CERC ancillary services regulations, CERC deviation settlement mechanism regulations, CEA flexible operation of thermal power plants regulations, MOP guidelines, storage policies, and SECI tenders, addresses many crucial issues. To ensure the seamless integration and optimal utilisation of renewable resources, it is essential to review and update grid codes and standards continuously. Regulatory changes must keep up with technological advancements and the evolving grid requirements. Priorities include setting standards and provisions for fast frequency response from inverter based resources (IBR), battery energy storage systems (BESS), grid-forming capabilities of inverters, protective settings, and construction standards for renewable energy sources.

Expertise shared by: Venkateshan M, Deputy General Manager, SRLDC, Grid-India

Note: The views expressed in the article are of the author and may or may not reflect the views of Grid-India