Grid Integration of Large Scale Renewable Generation – Initiatives in Indian Power System

India is continuously progressing in capacity addition through conventional as well as renewable resources to meet its growing demand. Out of 234 GW present installed capacity, renewable capacity contribution is about 13%, which is primarily dominated by wind generation (70%). Abundant Renewable Potential in the country presents excellent solution to meet challenges like long term energy requirements, attaining energy security along with affordability, addressing climate change concerns etc. Government is also promoting development of renewable generation through an attractive mix of fiscal and financial incentives as well as conducive policy environment. It is envisaged that more than 30 GW renewable generation capacity shall be added in the 12th Plan period (2016–17). MNRE has also projected about 235 GW renewable capacity by 2030. Above quantum of envisaged renewable capacity would lead to increase in renewable capacity penetration to 17% (2017) & 33% (2030) and renewable energy penetration to 9% (2017) & 16% (2030).

Renewable energy is characterized by intermittency and variability which presents various challenges in its grid integration for maintaining grid stability & security in various scenarios. In order to address above challenges in high penetration regime, there is a need to introduce more flexibility in generation portfolio as well as consumption.

Flexibility in generation is introduced through utilization of fast-ramping conventional energy sources like Gas, Hydro, Pumped Storage Hydro, Energy Storage technologies like large scale batteries (Flow, Li-Ion etc.). Indian system is dominated by coal based generation therefore introduction of flexibility in thermal generation though suitable technical and market mechanism incentivizing operation of such plants providing flexibility also need to be explored. In future, super critical technology generating units are to be deployed for coal based generation, which can operate at the designed super-critical steam parameters between 80–100% of rated capacity, providing added flexibility.

Flexibility in consumption to be introduced through demand side management (DSM)/demand, encourages consumers to modify patterns of electricity usage. DSM/DR utilizes Smart Grid technologies, to reduce the operational cost of renewable integration through measures such as load shifting and peak shaving. Also, other measures to smooth out the intermittency and variability include enlarging the balancing area through strong transmission interconnections, forecasting of renewable generation, real time monitoring of renewable generation, dynamic compensation etc.

Considering envisaged renewable penetration level by 12th plan period (2016–17) and need of addressing challenges as well as infrastructure requirements to facilitate RE grid integration, extensive studies were carried out for evolution of “Green Energy Corridors”. As part of the study, challenges on account of grid integration of large scale renewable identified on Grid Operational as well as System Planning front and suggested remedial measures suitable to Indian context.

Studies identified transmission infrastructure requirement both at Intra state within state, for absorption of RE power in the host state, as well as Inter-state, for transfer of RE power out of the host state. Strong grid interconnection shall also help in enlarging power-balancing area. Intermittent/variable nature of RE sources results in wide variations in quantum and direction of power flow on the Inter state high capacity transmission corridors. This requires placement of Dynamic reactive compensation in the form of STATCOM/SVC at strategic locations to provide dynamic voltage support for smooth operation and maintaining grid security. This shall also help in addressing fault ride through issues in RE complexes.

In addition, the study evolves requirement of other control infrastructure like establishment of Renewable Energy management centres (REMC) equipped with advanced forecasting tools, weather monitoring stations as well as Real time measurement/monitoring schemes through WAMS applications. Energy Storage requirement has also been identified to provide balancing reserves.

In this paper, envisaged capacity addition of RE generation in next 5–6 years in various RE rich states have been presented. Paper also deliberates challenges of integration of large scale Renewable into grid and suitable mitigating measures. Studies for evolution of Green Energy Corridors are also discussed. Paper highlights perspective transmissions plan for renewables that serve as a road map up to year 2030 in Indian context.