Abstract

This paper is an attempt to emphasize on the importance of the non-conventional energy sources of which small hydropower generation is one. It deals with the cogeneration of hydro power along with thermal power stations. The paper describes how it will be effective to increase the overall efficiency of the thermal plant. Also it emphasizes on the appropriate and maximum utilization of both, the flow and discharge of the water used in thermal plants to generate hydro power. The paper also explores the various possibilities of harnessing energy at different locations in plant. Advantages and limitations of such an arrangement is appropriately dealt with. An introduction to the upcoming technology of the modified electronic governor control system is also dealt with.

Introduction

What Is Small Hydro Power and it's Need:

Fuel prices are going up very rapidly. We need to think upon harnessing non-conventional sources of energy to our maximum. Up till now only those sites, which are large enough, where economy of scale enabled the production of energy at cost low enough to compete thermal power, fueled with low cost oil were used. But now, with advancement in developments of turbines that can use " small falls & discharges" efficiently has led to development of small hydro installation to a large extent.

Classification

As per as the bureau of the Indian standards

Depending on amount of power produced:

• Small hydro project: 1001-6000 KW

• Mini hydro project: 101-1000 KW

• Micro hydro project: below 100 KW

• Independent: only for power generation.

• Sub ordinate: apart from power other purposes are solved. E.g. irrigation, water supply etc.

• Small head but high discharges.

• High heads but small discharges.

Overview of Small Hydro Electric Scheme with Respect to its Installation Along with Thermal Project

1. Diversion: It allows water for proper intake.

2. Desilting Chamber: This is not necessary in case of our topic because water is coming after a series of waste removal process.

3. Water Conducting System: Proper inlet and exit of water is maintained through this system.

4. Forebay: In this case, canal itself leads water to turbine, thus it serves as forebay.

5. Surge Tank: When load on turbine reduces governor automatically closes inlet gates partially to reduce inflow to turbines . It also reduces water hammer pressure.

6. Penstock: Short length penstocks carry extra pressure and thus are best suited for such purposes.

7. Power House: Consists of turbines and other control systems.

8. Tail Race: Generally a canal for closed as well as open circuit water system.

In thermal power plant, water is main working fluid, whether to derive steam or to cool it, excess amount of it is used, and over the whole process the flow and head of water may be utilized to harness energy . Depending upon the nature of water circuit in power plant we can have different possibilities . They are as follows:

General Advantages of SHP

1. Low gestation periods.

2. Short time for developing a unit. Investment is also less as compared to big hydro projects.

3. Running cost is very less.

4. Operation & maintenance is one of the simples of all other power utilities.

5. It is pollution free.

6. No environmental hazards, such as the submerging of lands and ecological unbalance.

1. Full utilization of running water in the plant also cogeneration increases the overall efficiency of the plant.

2. Low development costs, as well defined framework already exists for the thermal power plant.

3. It can be synchronized with the grid . Due to this the plant utilization factor increases considerably, making the project economically viable.

4. Large colonies of thermal projects may be electrified using such installations.

1. Construction of SHP requires labor, time and investment.

2. Non-Availability of indigenous technology and import procedures are time consuming.

3. General lack of awareness of benefits from SHP.

Development of small-scale projects has been possible only because of upcoming technologies in field of turbo machinery, because they are capable of generating power even from very small heads . With the development of tubular, straflow and bulb turbines it is possible to utilize even smaller heads . Kaplan and Francis turbines are the other turbines that utilize low heads.

Recent Technologies: A Discussion

With the development of Modified Electronic Governor Control System the operation of SHP becomes much more simple . In such a system the gates are positioned at any desired position by pressing the required keys . There are controllers meant for runner blade control, operated only after turbine attains 80% speed . For desired opening and closing of runner blade during testing and calibration there are adequate mechanisms provided . Water level is directly maintained through changing gate positions. For plant start up all necessary auxiliaries should be started first which indication lamps on the control panel can verify . Proper synchronization between opening of gates and speed of the turbine is maintained through this modified electronic governor control system . The speed of the turbine is maintained within specified limits. Once the speed of the turbine is stabilized, the generator breaker is closed for synchronizing with the grid . Immediately after closing the breaker, some load should be taken on generator to avoid possibility of motoring operation . For planned shutdown load is reduced gradually. There are proper arrangements on the control panel itself to meet with emergencies.

Conclusions

Small-scale hydro plants can be set up with thermal power plants to increase the efficiency as well as the plant utilization factor.

References

1. John Finnemore, Joseph. B.Franzini, Fluid Mechanics with Engineering Applications, Mc-Grawhill Publishers, Chapter 16 -- Hydraulic Machines -- Turbines.

2. Victor Streeter, K.W. Bredford, E Benjamin Wylie, Fluid Mechanics, Mc-Grawhill Publishers, Chapter -- 11/ Turbomachinery.

3. Punamia, Hydropower Engineering, Laxmi Publications,P-850.

4. G.D. Rai, Non-conventional Energy Sources, Khanna Publishers, Small Scale Hydroelectricity,p-541.

5. Bureau Of Indian Standards, www.bis.com. (For classification of hydro power plants).

6. Alstom, Power Hydro, Website Www.Alstom.Com.

7. McGraw-Hill Series In Mechanical Engineering, P-399

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