Absorbing Renewables

Green energy corridors to improve grid integration

With the announcement of aggressive renewable energy targets, India has set an example for other countries in the world. While the pace of renewable capacity additions in the country has gained significant attention, the sector is fraught with constraints and a lot still needs to be accomplished in order to achieve these high targets.

Unlike conventional energy, renewable energy is intermittent in nature and can cause grid instability. Difficulties in evacuating power from renewable energy sources and the lack of operational mechanisms to accommodate intermittency make large scale renewable energy integration very difficult. As long as renewable energy penetration in the country’s total energy mix is low, its intermittent nature is not a cause for concern. In addition, the gestation period of a renewable energy plant is short as compared to other energy generation sources. Therefore, renewable energy transmission needs to be planned much ahead of its upcoming generation.

Under the Paris agreement, India has pledged to generate 40 per cent of electricity through non-fossil fuels by 2030, which will translate into nearly 300 GW of renewable energy capacity. While the focus has been on increasing the renewable capacity, an adequate transmission infrastructure also needs to be developed to absorb large capacity additions without affecting the grid.

In Tamil Nadu, developers have faced several instances of wind and solar power curtailment due to poor transmission facilities. In addition, millions of units of renewable energy are lost due to congestion in the inter-state transmission corridor.

Overcoming challenges

The government is addressing these concerns by constructing green energy corridors and issuing advisories to state utilities. In the Twelfth Five Year Plan, the government announced the National Green Corridor Programme (NGCP) worth Rs 430 billion to facilitate the grid integration of large scale renewable energy. Two green corridor transmission networks were proposed under the programme, which has been divided into two phases. The first phase Green Energy Corridors-I, envisages the construction of the inter-state transmission network for connecting renewable energy-rich states. This phase of the programme is designed to support 33 GW of solar and wind power while the second phase will link 22 GW of capacity. The inter-state transmission network under the first phase of the programme entails the construction of a 400 kV D/C Ajmer (New) to Ajmer (RVPN) line, a 200 kV D/C Chittorgarh (New) to Chittorgarh (RVPN) line, a 400 kV D/C Tirunelveli PS to Tuticorin PS line-1 and a 400 kV D/C Tirunelveli-Tuticorin PS line-2. The first phase of the programme is expected to operationalise by March 2017.

The second phase of the programme Green Energy Corridors-II has also commenced. It is connecting solar parks across different states including Andhra Pradesh, Madhya Pradesh, Karnataka, Rajasthan and Gujarat. The NGCP aims to strengthen the transmission infrastructure at the inter- and intra-state level with the establishment of renewable energy management centres (REMCs) and other infrastructure such as dynamic reactive compensation solutions, energy storage systems and smart grid applications; forecasting of renewable generation; as well as real-time monitoring. It also covers the perspective plan for the integration of renewable energy by 2030.

A key component of the transmission infrastructure is the development of REMCs for the forecasting, scheduling and real-time tracking of renewable energy generation. A total of 11 REMCs have been planned by the government to be built across the country, alongside the state load dispatch centres and one at the national level. Moreover, owing to increasing grid complexity, the wide area management system is being implemented by the government as part of the green energy corridors project, wherein 1,700 phasor measurement units (PMUs) will be installed for better visualisation and situational awareness of the grid. Under Phase-I, a total of 1,186 PMUs will be installed along with 32 phasor data concentrators at control centres and the remaining 550 PMUs will be installed in the second phase.

The way forward

While the development of green energy corridors is the right step towards the development of a robust transmission infrastructure in the country, there has been

limited progress on this front so far. Going forward, the government needs to encourage the development of these projects to keep pace with the expected increase in renewable penetration from 6 per cent at present to 20 per cent in the future.

Based on a presentation by Rajesh Kumar, Assistant General Manager, Smart Grids, Power Grid Corporation of India Limited



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