India has installed capacity about 16 GW of wind power and about 1.3 GW of solar power. It is expected that we reach to about 20% of total requirement through renewable energy sources contributed predominantly by wind and solar power, the major constraint in large scale deployment of renewables is its variable in nature, which makes a difficult to absorb by grid especially when Indian northern grid and southern grid are having connection issues.
Large scale deployment of renewables not only require strategies to integrate supply side as well as demand side options enforce the need of smart grid technologies for integrating renewable technologies with grid. As per 12th plan, while the government is planning to add about 7000MW of renewables .it is important to assess the grid parameters to accommodate electricity injection from variable renewable sources to grid. The states such as Tamil Nadu where renewable penetration is highest (about 40% of renewables capacity). Integrating renewables with grid has become major bottleneck in the state .It requires different treatment to integrate solar as compared to wind power technologies because wind power is available predominantly during monsoon season (4 months) and the state has minimum electricity demand during to the season due to lack of agriculture and domestic load requirement.
Most of the grid substations are having power cuts due to over frequency as the power generated by wind farms in the state is not being evacuated because of lack of demand with in State. On one side the states do not have sufficient balancing reserves to absorb the variable nature of wind power at the same time. The transmission network is also not strong to absorb variable wind power, this requires investment in two fold. On one side the states need to improve transmission network, especially the southern grid needs to connect with the northern grid so that the higher wind capacities can be absorbed in Tamil Nadu. Generation from wind power during monsoon season is also aligned with hydro power generation and this puts further strain on the grid as some of the hydro power plants cannot be put off.
Annual load duration curves forTamil Nadu under different wind power scenarios
Electricity generation from renewables is traditionally under FIT (feed in tariff) route and utilities have to consider renewable electricity has a must run source and has to pay higher cost of electricity Procurement as compared to competing other sources during the monsoon season. The recent regulatory intervention are encouraging project developers to move from fixed tariff based system to Market based tariff system. Also introduction of scheduling from April 2013 for renewable sources (wind) will also help to better forecast the electricity generation. Introduction of smart grid technologies such as demand response management will also help the grid operates to manage electricity demand supply imbalance and will help large scale deployment of renewables in efficient and reliable manner. There is also a need to do investments in balancing reserves such as pumped hydro storage systems which will balance the surplus electricity generation from the wind and also absorb the grid fluctuations. Introduction of UI mechanism will also help the Grid operators to absorb large variability of renewable sources.
Large scale deployment of renewables require additional investments in balancing reserves which are costlier investment as compared to traditional electricity generation options. The balancing reserves can also be open cycle gas turbine working in tandem with large wind farm to absorb the fluctuations of wind power generations. The additional investments in balancing reserves have been traditionally meet through introduction of system balancing charges in various countries. it is proposed that introduction about 0.3-0.4 Rs /Kwh balancing cost in the wind power generation will help in designing Grid with sufficient balancing reserves.
Dr Sanjay Vashishtha & Rishikesh muthyal