Issues with large scale Renewable Energy integration and the way out

Renewable Energy (RE) particularly Wind and Solar have huge potential and going to be the dominant energy sources in near future. Their large scale integration into the grid is going to cause certain serious issues which need to be addressed. 

Intermittent and Variable in nature:

As we know wind and solar are intermittent and variable in nature, their output depends on the availability of wind and sunlight. Variation in the output may cause significant change in power flow over the transmission and distribution lines, affecting the reliability and security of the power system. 

Most of these RE power plants are located far away from the major load centres and existing transmission lines. Usually these RE plants are connected to the grid at a voltage of 33 kV, 66 kV, 132 kV or 220 kV depending on the capacity of the plant and its location.

Sluggish development of Transmission Infrastructure:

Normally the gestation period of these RE plants are 6 to 12 months, whereas the development of a transmission infrastructure takes some 4 to 5 years depending on the conditions like Right of Way (RoW) requirement, clearances from various government organizations, financial condition of the executing agencies etc.

Limited Reactive Power support:

Currently many of the wind turbines have induction generators which either have no or limited reactive power support, thus causing issues like voltage regulation. Same is the case with line commutated solar PV systems.

Thus, the large scale integration of RE into the grid along with insufficient transmission facility is going to cause serious issues like congestion, voltage regulation, nodal price, supply reliability and security of the system. 

Mitigation methods: 

Some mitigation methods for the above said issues are:

1.   Variation and intermittency in power supply can be better handled by a strong interconnected transmission system.

2. Reactive power support in the form of Static VAr Compensator (SVC) or STATCOM can be provided at the RE power plants or some strategic locations to take care for the reactive compensation and voltage regulation.

3.   Private participation in the transmission sector will help to enhance the execution capability.

4.  Strong weather and hence output forecasting technique along with a strong real time interaction with the System Operator (SO) with help in mitigating certain grid code issues.

5. Some form of storage capacity whether it’s the pumped storage hydro plant or large scale battery storage, will also help to counter a variety of issues discussed earlier.

6.  New energy market structures incorporating special ancillary services such as reactive support services, spinning reserves, flexible generation etc is also going to strengthen the grid operation in the advent of large scale RE penetration.   

7. A separate Renewable Energy Management Centre (REMC), with advanced communication and control techniques, should be planned for the enhanced security and reliability.

So in near future we are going to witness a new and much eco-friendly power system, particularly in the developing countries like India.

Swift development of Transmission infrastructure in India: The Joint Venture route

Last Updated: 31 January 2017

Issues with Indian Transmission sector:

Installed generation capacity in India has nearly doubled in the recent times, mainly because of restructuring and deregulation of the power sector and the thrust given to Renewable energy sources. But the transmission sector is way lagging behind the generation, as the former was not given the due consideration. 

Some of the major obstacles in the development of transmission infrastructure in the country has been the difficulty in acquiring land, delayed forest clearances, and the government monopoly. 

Transmission unavailability has resulted in major load-sheddings in various areas, despite of surplus energy in certain regions. This has led to unsold generation capacity, low market prices and low plant load factor.
  
“The Electricity Laws (Amendment) Act 1998” treats transmission as a distinct activity in India and has made provisions for private sector investment in transmission system. In order to activate resources from private sector, Government of India issued certain guidelines for private sector participation in transmission sector in the year 2000. 

Methods envisaged for private sector participation in Indian Transmission sector:

One of the methods envisaged for private sector participation in transmission was through Joint Venture, wherein the Central/State Transmission Utilities (CTU/STU) shall own at least 26% equity and the balance shall be contributed by the Joint Venture Partner. 

The second route was all the way through Independent Private Transmission Company (IPTC), wherein 100% equity shall be owned by the private body. The CTU/STU will do the planning and identify approved transmission system or part thereof for implementation and execution by the private sector. 

Ministry of Power has also initiated Tariff Based Competitive Bidding Process for development and strengthening of Transmission system through private sector participation.

The aim is speedy development of transmission infrastructure in India, and to bring in potential investors. Since the power demand is increasing at a faster rate, gestation period of generating plants are reducing now it’s time for the transmission sector in the country to ramp up.

As a pilot project on JV method, Powerlinks Transmission Ltd., a joint venture between the Tata Power Company Ltd. (51%) and Power Grid Corp. of India Ltd. (49%) was selected through International Competitive bidding for the execution of 400 kV D/C transmission line associated with Tala Hydro Project, costing about a thousand plus Crores. The transmission project with a route length of around 1166 km connects Siliguri (West Bengal) and Mandola (Uttar Pradesh). This project which is in operation since 2006 has opened up Public-Private Partnership (PPP) in the transmission sector in India. Success achieved under JV route of private participation has encouraged POWERGRID to identify many more projects under this route.