Abstract
During this literature review various issues faced for grid integration of RES will be studied and shed light on. This gives opportunity to put forward ideas which can solve the issues faced in integration. With the technological advancements in Renewable Energy Sources (RES), increasing GHG, depleting conventional resources and never-ending need for energy, world is focusing on renewable sources with higher efficiency. Renewable Energy is available in abundance but can be harvested under certain conditions depending on various factors like geographical location and environmental conditions.
Index Terms—Renewable Energy Source, Grid Integration, Feasible Solution
Introduction
he most important factor for growth of any economy is power, that’s why it is considered as core industry as various sectors like agriculture, transportation, manufacturing, etc. which contribute in economic growth depend on it. As the GDP is increasing exponentially the hunger for energy is also growing to keep up with the GDP. There are many challenges to integrate RES in grid integration, therefore it is necessary to find feasible solutions for these challenges. Integration to conventional grid depends on the quantity of power generation, big power generation units are directly connected to conventional transmission grids and the small power generations are connected to distributed grids.
127 our experts are availableright now
The peak demand of electricity for India is more than 145GW(June’15) which is expected to go above 200GW in 2016-17 (12th plan) and more than 283GW by the end of 2021-22 (13th plan) as given in the 18th EPS report of CEA. There is a huge requirement of power generation through RES as well as conventional sources to reduce the gap between demand and supply. India’s geographical location and diversity of topography gives it abundant potential for renewable energy which can be utilized to counteract the following challenges: Future energy requirements, energy security with affordability, environmental concerns, etc.
Government is providing a mixture of fiscal and financial incentives for development of renewable generation and has conducive policy environment. It is estimated that by 2018-19 more than 30 GW renewable generation capacity and 20 GW of solar energy will be induced in the 12th Plan period. MNRE has also predicted that 175 GW renewable capacity will be available by 2022. Renewable energy is variable and that creates various challenges for its grid integration and maintaining grid stability & security.
Due to large demography, demand varies over the daily as well as on seasonal/regional basis. We need to introduce more flexibility with quick ramping features in generation units using mixture of various fuel technologies like Hydro & Gas. Strong grid interconnection will help in increasing power-balancing area, the variable nature of RES results in wide variations in quantum and direction of power flow on the transmission grid. 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 [1].
Present Situation
India is a developing country and ranks 3rd in fastest growing economies in the world to be the world’s sixth largest economy with 8.2% increase of GDP in first quarter of financial year 2018-19. Such tremendous development and growth require lots of energy. According to “Energy Statistics 2017” by CSO India ranks 3rd in energy consumption. According to BP statistical review of world energy in 2017 India gets its 92% primary energy from fossil fuels. Due to increasing population and exponential economic growth Energy consumed by India in 2040 will be higher than all developed countries of the world. Fig. 1- Primary Energy Consumption in India The power sector in India is one of the most diversified in the world.
The power sector in India is progressing in generation through conventional i.e. coal, lignite, gas, hydro and nuclear power and renewable sources like wind, solar, hydro, Biomass etc. Presently total installed generation capacity in the country is about 275 GW (June’15) which constitute capacity from Grid Integration of Renewable Energy Sources in India: Challenges and Feasible Solutions Hrishikesh Mokashi University of Colorado Boulder ECEN Department [email protected] T 2 conventional sources (87%) like Coal (167GW), Gas(23GW), Nuclear (5.8GW) and large hydro (42GW). Balance 35.8 GW (13%) contribution is from renewable generation capacity contribution Wind(23.4GW), Solar(4GW), SHP(4GW) and biomass/biogas (4.4GW) generation.
Challenges
Renewable integration on large scale to meet system security and stability leads to new requirements in the Power System. During analysis, challenges identified in Grid integration and operating are as following.
- Stress on distribution system due to variability and intermittency.
- Low gestation period of renewable generation as compare to development of transmission strengthening, constraints may arise because of large difference of gestations periods without integrated planning approach.
- Locations of solar and wind plants are generally far away from areas having high load.
- Most wind plants not able to operate during high voltage sags.
- Some wind turbines use reactive power from the system which affects the system negatively.
- Technical Issues:
- Power Quality: Harmonics, frequency and voltage fluctuation
- Power Fluctuation: Small time power fluctuations, long time or seasonal power fluctuations
- Storage
- Protection
- Optimal Placement of sources
- Non-technical issues:
- Lack of skilled man-power
- Initial costs [5]
Solutions
The renewable energy sources such as solar, wind etc. have proven major players in the transition towards green energy sources. As the number of renewable energy sources and distributed generators are increasing it requires new management systems for the operation and management of the grid to improve the power-supply reliability and quality. Considering the given issues some of the possible solutions have been proposed by researchers.
The power-electronics has as imminent role in generation and in integration of RES into the grid and is widely used and growing at a very fast pace as these applications integrate with the grid- based systems. Power electronics has evolved rapidly in last few years mainly due to two factors-1) The development of fast semiconductor switches capable to handle high switching frequencies and powers. 2) Real- time computer controllers that can implement advanced and complex control algorithms.
Advantage of Renewable source is the power generated can be controlled by distributing the RES to small units in a very large area instead of concentrating in one area. Example output from large solar PV system (rating tens of MW) can be affected up to 70% in a span of 5-10 minutes by natural phenomenon like clouds. Large number of small solar PV system should be installed in larger geographical area. The fluctuation of total output power can be minimized because of local problem can affect only small unit power not the total output power.
Dor irrigation purposes power is supplied by conventional grid during night time as the load is low. If the renewable sources are used during day time this power for irrigation purposes instead of storing the energy, it gives very high efficiency approx. 80% to 90% and the cost of solar water pumping is much lesser than the induction motor pumping type.
There is security and power stability concern as in large solar PV plant output power is fluctuating during the whole day and this power is fed to the grid and continuously fluctuating power gives rise to the security concern to the grid for making stable grid.
One of the solutions in integration of renewable energy solution is directly integration renewable energy resources in the rural area where there is no electricity provided at this moment. Instead of creating infrastructure from Transmitting AC voltage a DC distribution system can be directly build integration the power generated by the renewable energy resources to the load directly without any need of DC-AC-DC conversion.
Conclusion
In this literature review, to grid integration problems faced while grid integration of RES and their feasible solutions in the literature have been reviewed. To minimize the variation problems power electronics devices are feasible options. Energy storage and use of dump load and MPPT can be used for reducing the power fluctuations in PV systems. We can upgrade balance of systems by incorporating the new materials and storage elements could reduce the problems associated with grid integration. Balancing requirement is the primary need to address issues related to integration of large-scale renewables.
For this analyzing the renewable energy sources and forecasting, strong grid integration, flexible generation, dynamic compensation, energy storage system, are the solutions. Along with the technical interventions, there are many other political and local challenges faced in integration of RES which cannot be discussed in this review as these topics are very vast and no fixed data is available on this.
References
- I.S. Jha, Subir Sen, Kashish Bhambhani and Rajesh Kumar, “Grid integration of renewable energy sources”, Journal of Scientific and Technical Advancements, Volume 1, Issue 3, pp. 1-5, 2015.
- S.P. Sukhatme, “Meeting India’s future needs of electricity through renewable energy sources, Current Science”, Volume 101, No.5, pp.624-630, 10th September 2011. http://www.jstor.org/stable/24078624
- Manish Vaid, “A giant in transition, Observer Research Foundation”, 24th September 2018.
- Rahul Tongia, Samantha Gross, “Working to turn ambition into reality”, Brookings, Paper 4, September 2018. https://www.brookings.edu/wpcontent/uploads/2018/09/India-Renewable-Powerv10.pdf
- Ahmed Sharique Anees, “Grid Integration of Renewable Energy Sources: Challenges, Issues and Possible Solutions”, 978-1-4673-0934-9112/$31.00 ©20 12 IEEE.
