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Issues for Successful integration of Conventional Power and Renewable Energy

Submitted by: Manish Kumar Sah (15PGDM05A013)

Submitted to: Dr.Sagar M. Agravat (GERMI)

India has total installed capacity of 303 GW as on 31st May 2016. In this the Contribution of Non-renewable sources of power generation constituted to 72 % and the renewable source of power generation accounted for 13%. The other source is 15 % from Hydro section. Presently internationally, consensus is moving towards to accept Big Hydro as Renewable Source of Energy as well.

Coal is one of the main sources of Electricity Generation (Approx 61 %) in India, and also being seen as main source for power generation in future as well.

But, due to various Environmental Impacts, Rehabilitation & Resettlement issues, Global Warming, Disposal of Ash Generated from Fossil Fuel power plant, Non-availability of higher efficient technology, indirect unemployment on account of forest cutting to have coal mining, depletion of Natural resource etc, the dependency fossil fuel based generation in upcoming future is becoming most sensitive issues.

Hence, tapping of other non-conventional resources of power generation like solar, Tidal waves, Mini Hydro, Bio-gas, Geothermal, Off-shore and on-shore wind energy etc globally becomes most popular. Most of the countries are looking forwards to have better economical, sustainable and

best grid integrated power generation from renewable resources.

Under this Government of India is also being looking aggressively to have power generation of 100 GW from Solar Energy (60 MW from Solar Parks and 40 GW from Roof Top Solar), 60 GW from Wind, 5 GW from small Hydro and 10 GW from Biomass. There are various issues existed / recognized in integration of Renewable/Non-conventional sources of power to grid along with conventional source of energy. Some of the issues in integration of conventional power with renewable energy are listed below:

I. Stability of Grid, by introduction of Renewable Energy

II. Cost of Generation through renewable resources

III. Difficult scheduling of power generation through Wind Energy

IV. Difficult scheduling of power generation from Solar in rainy season.

V. Non-availability of Solar Generation in Night period, under big installed capacity will lead to frequency in-stability of grid.

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VI. Creating infrastructure i.e. Green Corridor for power evacuation from solar parks, huge capital investment requires.

VII. Reactive and inductive power generated due to installation of big capacity invertors.

VIII. Integration of PV generation at LT end.

IX. High Cost of energy storage system. X. Up gradation of LT end distribution

network to integrate roof top solar. Due to the above listed various issues,

the push towards putting infrastructure for power generation through renewable energy resources, had not yet been taken place in big way.

Also, learning from other European countries like Germany, UK, France etc, who have adopted aggressively the generation of power through renewable resources, but subsequently look back to conventional power for stability of grid. Germany is being making Thermal based power plant to provide stability to their grid, as their all installed solar plants and winds (72,400 MW) could being generating power more than 75 % of the time well below of 20% of the installed capacity. Whereas, installed 2900 MW thermal power station, generated twice of the total power generated from Solar and wind in 2012. Germany is indeed avoiding blackouts—by opening new coal- and gas-fired plants.

Coal, Hydro, Nuclear, Gas, and biomass power plants can ramp up and down on command to match their power output with

scheduled electricity demand. Unfortunately, wind turbines and photovoltaic panels can’t do that.

Integration problem of Roof Top Solar:

The roof top solar power generation will act as a small power generator as power supplier at LT end, which is resistive in nature instead of inductive in case of HT transmission.

Normal Inductive mode of transmission

(V1>V) (Fig-1)

LT Resistive mode of transmission (V1<V)

(Fig-2)

Under such circumstance, the LT level voltage at source end (PV cell Generation) will be high, leads to fluctuation of voltage as well higher level will be killing moment for the electrical appliance held at

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house.

To overcome such situation, smart

control of PV generation will be required. For this a two way communication has to be established, which will instruct/give command to PV cell to lower the voltage level up to the safe operating level.

Up gradation of whole LT distribution:

Till date the LT distribution networks have been designed for current flow from uni-direction, i.e. transformer end to load end.

(Fig .3)

Present distribution network designed for (V>V1>V2>V3 etc ……), where as in PV cell generation integration along with conventional power i.e. to grid/LT distribution end the reverse will be happen for some section of distribution network. (i.e. V3>V2>V1>V etc……).

Hence, whole distribution network

from 11KW downward have to be redesigned and developed accordingly. This may incur huge capital investment. Real power during Day time and reactive power during evening/night time: During Day time the real power will be fed into grid through solar park generation, but up on sun irradiation finishing in evening/night time some wind mill start rolling (As evening/night time air flow quit steady and highly suitable for power generation through wind mills), will required reactive power to start generating power, until it not stabilizes itself. For such condition PV generation inverters should be enables to meet the reactive power, as when the real power generation stopped. Presently, in wind mill separate inverters uses to meet reactive power after sourcing from grid. But, by enabling the PV generation inverters with inbuilt switched capacitors (Combinations of capacitors) the requirement of reactive power for wind mills could be met through small incremental investments.

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Flexible Operation of Conventional thermal power generating station: As it is well known that the base load requirements meets through thermal power generating stations and peak loads requirements meet through Hydro and Gas based combined Cycle generating stations. Due to longer durational requirement to synchronize with grid, thermal power stations are not supposed to operate on high flexible / regulated governing mode. But, after integration of renewable energy generation from Solar etc, from evening onwards the power generation from conventional sources I.e. Thermal stations have to ramped up immediately as the installed capacity of hydro power generation (Which could start generation within 15 minutes) and from Gas power station (Non-availability issue of gas) are not sufficient to meet the peak load demand in evening or night (Now also sifted to night in some states due to “Time of Day” tariff structure).

Hence, the adaptability of coal based generation towards highly flexible mode operation has to improved, in order to integrate Renewable energy Generation with conventional source of power generation.

It could also be achieved as the schedule of power generation from Renewable Energy especially from Solar could be easily predicted throughout the day and its non-availability time also be established according to sun movement path. Hence, by knowing the time of

generation stoppage from solar parks, accordingly the thermal power station could be made ready on per day basis to ramp up the generation as per scheduled demand profile of distribution companies. Besides the above issues and their probable way out, some additional strategic decisions could also helps India to make smooth integration of Renewable Energy with conventional source of power generation. Expansion of Pumped hydro generation: The pumped hydro generation could be effectively utilizes by using the day time generated power through renewable energy sources for storages of water in to dam and during evening or night time i.e. time of peak demand the generation from pumped hydro generation could be started. This will help in stabilizing the grid once the renewable (solar generation) energy goes out from grid in night time. Energy Storage Systems: Due to high cost associated in various mode of Energy Storage, still this principle not yet been accepted widely. Some of the energy storage methods like:

I. Chemical storage (Li-Ion battery, Lead-Acid battery, Hydrogen storage etc)

II. Mechanical (Fly wheel, Pumper Hydro, Compressed Air Energy Storage)

III. Electrical Storage (Super Capacitor, Super Conducting Magnetic Coil) and thermo electric storage.

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But, the technological advancement, lower efficiency and high cost still not proven enough to use the various methods of energy storage in commercial basis to integrate the renewable energy with conventional power.

Smart Grid enablement of national Grid: As the sun profile in India it has sufficient time difference (i.e. sun rise and sun set time) from south to north say Leh-Laddak. By, means of having smart grid enablement, the grid itself will meet the power requirements of south / east (where sun set occurs earlier) from north/west (where sun set quite an hour delay).

Hence, by establishing in well advance about the time of the sun ray falling throughout the day and having solar parks well located from North to South and East to West, the Smart Grid itself will stabilizes by sourcing of power from the solar parks, where sun ray falling is still going on to needy place (where generation from solar parks stopped). Grid connectivity with neighboring countries and promoting power trading: As Smart Grid enablement help in stabilizing the grid by sourcing power from generating location to needy part where sun set has taken place. In the same way by having grid connectivity and providing power to our neighboring countries through power trading (from our solar parks) and taking power say hydro power energy from Bhutan in night could further helps in integration of Renewable Energy with Conventional power.

Also, trading of surplus power generated through renewable source to neighboring countries in return of Natural gases i.e. from Myanmar, Pakistan, and Bangladesh could further help in re-energizing of Gas based power station and in return this will further helps in integration of Renewable Energy with Conventional Power generation.

Also by having agreement with neighboring countries like Myanmar, China to built Hydro Electric Power stations and operates on BOOT basis, could further not only enhances the ownership of power

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generated from Hydro power but the same could be well utilizes in stabilizing the grid for successful integration of Renewable Energy with Conventional Power.

Expansion and strengthening of Grid:

Grid Strength means that outages almost never occur, and that the grid has more capacity than necessary given current demand to accommodate renewable.

The capacity of transmission lines should be more than the total installed electricity generation capacity to accommodate the renewable generation at any moment.

Development of responsive and transparent Energy Market:

Renewable energy will be the dominant source of power in the coming years. The rules of the electricity market must therefore be developed to ensure that the electricity market will continue to ensure a reliable, cost efficient and environment-friendly power supply with a growing proportion of wind and solar power in the future. In the Energy Market the trading preferences should be given to renewable energy, so that market as well the consumers will become matured enough to use it along with conventional power.

Awareness of consumers through demand response management:

In order to integrate the renewable energy with conventional power the adaptability of energy supply system and

power generation system is very much required.

On the other hand the consumption

of electricity / load must also become more flexible i.e. by demand response management. Under this consumers could also play an important role (through incentive schemes) in stabilizing the grid frequency by participating in demand response management i.e. shading their load up on sudden non-availability of renewable energy.

Also, when a lot of electricity is available from renewable sources, variable tariffs can make it financially worthwhile to the end user. Summary:

The integration of Renewable Energy with Conventional Power Generation could be achieved by mean of adopting the following policies and techniques:

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I. Policy of Grid connectivity with neighboring countries and promoting power trading.

II. Smart Grid enablement of national Grid.

III. Expansion of Pumped hydro generation.

IV. Flexible Operation of Conventional thermal power generating station.

V. Smartness of inverters of PV cell generation to resolve issue of real power during Day time and reactive power during evening/night time.

VI. Up gradation of whole LT distribution. VII. Integration of Roof Top Solar through

02 way communication. VIII. Using various energy storage methods.

IX. Expansion and strengthening of Grid X. Development of responsive and

transparent Energy Market XI. Awareness of consumers through

demand response management

Conclusion: Hence, from the above we can say

that integration of Renewable Energy with conventional power is not a big challenge. It can be achieved by making some policy frame works, psychological acceptance and little investment to have requisite infrastructure.

The techno-commercial development energy storage system will further help in successful integration of Renewable Energy with conventional power generation.

Also, Renewable Energy is source of energy which could be further extended to achieving the target of Electricity to all by 2022 through the policy of establishing micro-grids and same could be further linked with national grid after development of infrastructure.