SMALL HYDRO PLANT PLANNING AND DEVELOPMENT : A CASE STUDY ON RENEWABLE ENERGY PROJECT MODELLING AND SIMULATION Priyabrata Adhikary
Susmita Kundu
G.M.I.T. (WBUT), Kolkata
M.S.I.T. (WBUT), Kolkata
Pankaj Kr Roy
Asis Mazumdar
S.W.R.E., Jadavpur University, Kolkata ABSTRACT Small hydropower projects [SHP] are a possible environment friendly solution in developing, hilly countries where small rivers are available, for rural electrification. SHPs have great importance because of their low administrative and executive costs, possibility of using water for drinking and irrigation purposes, suitability for rural areas and low environmental pollutions. SHP constructed at a remote area is capable of supplying electrical power to local consumers through an isolated transmission line which is not grid connected. In the present study an attempt has been made to develop a SHP model by means of carrying out a RETScreen and MATLAB based simulation. Simulation results indicate a possibility that renewable/alternative energy sources will replace the conventional energy sources in near future and standalone applications would be a feasible solution to the problem of distribution of electrical power at remote and distan locations. Keywords : Small Hydropower, Renewable Energy, RETScreen, MATLAB, Optimization 1. INTRODUCTION
power at a higher cost-per-watt. Small hydropower projects (i.e. up to 25 MW in India) are much more advantageous than conventional medium or large hydropower projects. Small hydropower plant requires very less flow or head compared to conventional hydropower plants. Reservoir is also not required for small hydropower projects as they are mostly run-of-river type[3]. Environmental and social impacts of small hydropower projects are also negligible compared to conventional medium or large hydropower projects. Small hydropower project schemes are classified as: Run-of-river scheme, Canal-based scheme, Dam-Toe scheme, Pumped storage scheme and In Stream type. Run-of-river scheme utilizes the instantaneous river flow without a dam. A weir or a barrage is constructed across the river simply to raise the water level slightly and divert water into a conductor system for power generation. Such a scheme is adopted in the case of a perennial river. Canal fall based schemes are planned to generate power by utilizing the flow and fall in the canal. These schemes may be planned in the canal itself or in the bypass channel. These are low head and high discharge schemes. These schemes are advantageous due to low gestation period, simple layout, no rehabilitation problems and no socioenvironmental problems. In Dam-Toe scheme the head is created by raising the water level behind the dam by storing natural flow and the powerhouse is placed at the toe of the dam or along the axis of the dam on either
Some industries, like oil refining, health care and power generation have (24x7) type continuous schedules almost from the day they start. When a company needs to move from 5-day operations to 7-day operations, the operating and maintenance strategy can result in significant problems if not handled properly and needs critical decision makings. Small hydropower projects are complex, interdisciplinary integrated systems, because there are large numbers of civil, mechanical and electrical components with different characteristics. The success of a small hydropower project is no longer dominated by only economic criteria. Several other criteria, such as environmental, socio-political and technical aspects need to be taken into consideration. The cost of clean-greenfriendly small hydroelectricity is relatively low i.e., Rs. 2.5/ KWH (approx.), compared to others (solar, wind, ocean, geo thermal etc.)[1,2] and thus making it a competitive source of renewable energy. In India, the total installed power generating capacity upto November 2015 was reported as 2,84,1423.4 MW out of which only 42,623.40 MW is through hydro power. The identified small hydro power potential sites are 19749.4 MW, out of which installed capacity are 4162.0 MW only till November 2015. Inaccurate design, improper selection of project or any parameter will have high negative impact on the overall cost and efficiency. Thus it will result in producing less
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side. The water is carried to the powerhouse through a penstock. Pumped storage scheme is a method of keeping water in reserve for peak period power demands by pumping water that has already flowed through the turbines back up a storage pool above the power plant at a time when customer demand or tariff for energy is low, such as during the middle of the night. The water is then allowed to flow back through the turbine-generators at times when demand is high and a heavy load is placed on the system. Because pumped storage reservoirs are relatively small, construction costs are generally low compared with conventional hydropower facilities. Run of river schemes are also planned in the river itself by with or without creating a barrage and are known as Instream schemes. 2. SHP-PLANNING AND DEVELOPMENT Small hydropower project development involves following stages as: Pre-feasibility Study; Feasibility Analysis; Engineering and Development; Construction and Commissioning. The small hydropower plant components are constantly stressed by a number of factors which affect the life of the individual components and of the power house. The usefulness of the equipment can be substantially increased by carrying out the proper operation by trained manpower and maintenance of the machine or parts by skilled manpower and by taking such maintenance steps many faults can be prevented. Small Hydropower Plant operation can be divided under four verticals as: Operation Management, Water Management, Maintenance Management and Personnel Management. Small Hydropower Plant maintenance ensures: reliable and uninterrupted power supply; full utilization of existing plant and machines; reduced O&M cost; reduced outages, breakdown and better efficiency; increased durability. Maintenance of power plant includes – daily check schedules, weekly check schedules, monthly check schedules, half yearly check schedules, annual overhauling. Small Hydropower Plant maintenance is of four types as: Breakdown Maintenance, Routine Maintenance, Preventative Maintenance and Capital Maintenance[4,5]. In the final analysis of any renewable energy research, it is the energy delivered versus the investment cost which has to be optimized for a feasible engineering solution. Inaccurate design or improper selection of any parameter will have high negative impact on the overall cost and efficiency. Thus it will result in producing less power at a higher cost-per-watt. Small hydropower projects (SHP) are complex, interdisciplinary integrated systems, because there are large numbers of civil, mechanical and electrical components with different characteristics. There are two basic components in all four types of SHP schemes; i.e., civil works (Diversion and intake, De-silting tank, Power channel, Fore-bay, Penstock, Powerhouse building, Tail race channel etc.)
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and electro-mechanical equipment (Valves; Hydraulic Turbine - Pelton, Francis, Kaplan, Cross Flow etc.; Generator-Synchronous or Asynchronous type etc.). The hydraulic turbine-generator assembly is the heart of any small hydropower project. Pelton, Francis, Kaplan and Cross Flow turbines are used in high head, medium head, low head and ultra low head applications respectively. Synchronous generators are used mostly for mini or isolated grids whereas asynchronous generators are generally used when connected to comparatively large grids. Most of the components are same in different types of schemes; some components, however, are different. The development of small hydro projects typically takes from 2 to 5 years to complete, from conception to final commissioning[4,5]. This time is required to undertake studies and design work, to receive the necessary approvals and to construct the project. Once constructed, small hydro plants require little maintenance over their useful life, which can be well over 35 to 50 years. 3. SHP-R.M.U. & L.E. Renovation, Modernization, Up-rating and Life Extension (RMU&LE) is redesigning, retrofitting and upgrading 7-years or older SHP (up to 25 MW) and some of their components with the aim of achieving enhanced safety, reliability, durability and efficiency. It is done before complete replacement of the plant and machines. The optimization of generation from the existing SHP capacity is of utmost importance. The installation of new SHP involves much higher investment and longer gestation period. In view of the large quantum of finances required to install additional capacity, the optimization of generation from the existing SHP generating capacity through Renovation, Modernization, Up-rating and Life Extension (RMU&LE) has been considered to be the best option to achieve additional capacity and generation at a much lower cost and in a shorter time[6,7]. Recently in order to augment the hydropower generation and improve the availability of existing hydropower projects, M.N.R.E. (G.O.I.) placed special emphasis on RMU&LE of various existing old SHP in the country namely: 20.4 MW Pathri SHP (Hardwar), 9.3 MW Mohammadpur SHP (Hardwar), 3MW Galogi SHP (Dehradun) etc. Renovation (or Rehabilitation or Refurbishment) aims at extending the SHP life. Whereas restoration work is done to recover the damages caused due to natural calamity. The first step towards refurbishment is to assess the existing condition of machine & its various components. For this, a very detailed study (temperature, vibrations & metallurgy etc.) needs to be done. The power plant engineers may not be competent enough to do it alone. This work should be got done from manufacturers or experts as they know the latest techniques of stress analysis which can be used to get actual operating
Small Hydro Plant Planning & Development : A Case Study on Renewable Energy Project Modeling & Simulation
stresses at different heads & output. However plant engineers should have sufficient knowledge of the tests to be performed & data to be collected. These electrical and mechanical studies will indicate the health and residual life of plant or machines. It would be the main deciding factor for replacement or refurbishment of different components of machines. More than 200 old hydropower stations exist in India. RMU&LE of SHP concerns only old stations (7–Year or older stations). MNRE (India) gives financial support for RMU&LE of SHP stations. Consequences of SHP aging are: lowering of plant performance, reduced generation, uneconomical operation, difficult maintenance. Renovation doesn’t only mean replacement or repair of worn out and damaged parts. It also includes use of new materials, designs and technologies for improving efficiency and reliability of the power station and enhancing generation. Renovation is advantageous as it takes lesser time (1-3 yrs) than new project development (3-5 Yrs). It doesn’t require any statutory clearances or rehabilitation of people involved. But it extends plant life by only 20 –25 years. The governing factors of Renovation are: project cost, project life, shutdown time, efficiency and project feasibility. Hence renovation is considered as an opportunity to modernize or up-rate a plant[7,8]. Modernization aims at enhancing the plant performance. Cost - benefit analysis is essential for modernization. Benefits of modernization are: increased plant output; improved efficiency; higher availability; higher reliability etc. Briefly it includes both replacements of manual systems with modern accessories and controls (Gates, Governors, and Relays etc.) as well as addition of new features (PLC or SCADA etc.) for smooth operation of the SHP. Up-rating aims at increasing the SHP capacity. Essential studies need to be carried out for assessing up-rating feasibility includes: assessment of existing condition of machine; study general guidelines; studies on electrical equipments & parts; studies on mechanical equipments & parts. An up-rating possibility has to be carefully studied to identify the possibility of increasing efficiency or capacity of turbines & generators. Again it has to be carefully studied to identify the possibility of utilizing increased discharge or head (if any). It may be achieved by up-rating of existing machines through technology up-gradation, unit addition or revising operating margins (10–30%). It may also be achieved by adding new technology or replacing old equipments or technology with advanced ones (use of Class F insulation in stator, use of faster relays or breakers, use of advanced runner blade material, use of PLC or SCADA etc.). Systematic way of checking health of every component of the old SHP is done by Residual Life Assessment and Life Extension (RLA&LE) studies. This study helps in assessing the
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up-rating of the existing facilities of the plants. RLA&LE studies are helpful in determining which component of the plant to be retained and which one to be discarded or replaced[8,9]. 4. SHP PLANNING AND DEVELOPMENT TOOLS Computer software’s designated for SHP project (up to 25 MW in India) assessment can be integrated with or without GIS. To assess river flow, there are two main approaches: the flow duration curve (FDC) as in RETScreen and the simulated stream-flow (model) methods or flood frequency analysis (FFA) as in IMP 5.0. Computer programs intended for modeling and simulation of power generation and entire isolated or central grid such as MATLAB or SCILAB is also available commercially. RET Screen: This is a MS Excel based unique decision support tool developed with the contribution of numerous experts from government, industry, and academia. The software, provided free-of-charge, can be used worldwide to evaluate the energy production and savings, costs, emission reductions, financial viability and risk for various types of Renewable-energy and Energy efficient Technologies (RETs). The software also includes product, project, hydrology and climate databases, a detailed online user manual, and case studies. The RETScreen Small Hydro Project Model software can be used worldwide to easily evaluate central-grid, isolated-grid and off-grid hydro projects of any SHPP size. It is applicable for India as well as other countries. It has been used here for hydrological analysis (Flow Duration Curve and Power Curve estimation) for the case study project[4,8]. MATLAB: Again setting up and solving a large optimization problem for portfolio optimization, constrained data fitting, parameter estimation, or other applications can be a challenging task. As a result, it is common to first set up and solve a smaller, simpler version of the problem and then scale up to the large-scale problem. Working with a smaller version reduces the time that it takes to identify key relationships in the model, makes the model easier to debug, and enables you to identify an efficient solution that can be used for the large scale problem. Three techniques for finding a control strategy for optimal operation of a hydroelectric dam: using a nonlinear optimization algorithm, a nonlinear optimization algorithm with derivative functions, and quadratic programming can be achieved by MATLAB simulink. It has been used here for simulating the case study project[9,10]. 5. RESULT AND DISCUSSION: A CASE STUDY Here RETScreen (Developer: Natural Resources Canada) software has been used for the hydrologic calculations whereas MATLAB simulink has been used for simulation purpose.
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6 Table 1 Small Hydro Project Specification (A Case Study)
software is fully capable of simulating run of river (ROR) small hydro plant under change in load, speed, voltage etc. and hence demonstrates the dynamic behavior of the same.
Fig. 3 : MATLAB Simulation of each 2 MW SHP
RETScreen calculates the estimated green energy delivered for SHP projects, based on the adjusted available flow (flow-duration curve), the design flow, the residual flow, the load (load-duration curve), the gross head and the efficiencies or losses. The F.D.C. (flow duration curve) of (2 MW x 3 Nos.) SHP site has been shown in Figure 1. Available energy is simply calculated by integrating the power-duration curve.
In the present case, the turbine-generator assembly is envisaged to be connected to isolated grid. The simulation results obtained (voltage and current) also complies with the actual data for optimal green power generation of same capacity.
Fig. 1 : F.D.C. and Power Curve of (2 MW x 3) SHP
Combined turbine performance is also calculated as shown in Figure 2 at regular intervals on the flow duration curve.
Fig. 4 : Generated Voltage of 2 MW in p.u. (Mini Grid)
Hence simulations performed on the isolated grid scheme have demonstrated the efficacy of the proposed virtual SHP model.
Fig. 2 : Turbine Efficiency Curve of (2 MW x 3) SHP
Finally simulation using MATLAB for each 2MW SHP including its various components (Turbine, Generator, Transformer etc.) has been carried out. The developed
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Fig. 5 : Generated Current of 2 MW in p.u. (Mini Grid)
Small Hydro Plant Planning & Development : A Case Study on Renewable Energy Project Modeling & Simulation
6. CONCLUSION A small hydro power plant (SHP) model has been successfully simulated using RETScreen and MATLAB Simulink. Simulations performed on the proposed control scheme have demonstrated the efficacy of the proposed virtual SHP model. There is a series of standards, guidelines and manuals on hydropower development or RMU&LE issued by international standards organizations like ISO, IEC, IEEE, ASME, USBR and the national statuary bodies of several countries, including India (CEA, REC, BIS and CBIP). But most of them were prepared keeping in view the large or medium hydropower projects. To make SHP cost effective and reliable, standard guidelines are required covering entire range of SHP (Pico, Micro, Mini and Small) activities. While these projects are developed by various state agencies responsible for renewable energy, the projects are normally maintained with local community participation. Such SHP faces the problem of poor plant load factor and making financial return difficult for the plant. But this provides opportunities for the overall socio-economic development of the rural area and hence gaining importance widely. This research is motivated by the need to help planners, developers, owners or consultants to cope with the changes in concepts and values concerning the planning, development, operation and maintenance of local sustainable energy supply systems (small hydro).
Acknowledgements The authors wish to thank S.W.R.E., Jadavpur University, Kolkata and BHPC, Bihar for the valuable technical literature support. The authors declare that there is no conflict of interests. REFERENCES 1. Diamantino Durão, Leão Rodrigues, Mechanisms for Renewable Ocean Energy Conversion, International Review of Mechanical Engineering (IREME) 7(3), pp. 534-540, 2013 2. Yusuke Katayama, Shouichiro Iio, Tomomi Uchiyama, Toshihiko Ikeda, Effect of Flow Condition on Undershot Water Wheel Performance, International
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Review of Mechanical Engineering (IREME) 8(6), pp. 1005-1011, 2014 3. Yusuke Katayama,Shouichiro Iio,Salisa Veerapun, Effect of Runner Position on Performance for Open Type Cross-Flow Turbine Utilizing Waterfalls,International Review of Mechanical Engineering (IREME) 8(6), pp. 10012-1016, 2014 4. Priyabrata Adhikary, Pankaj Kr Roy, Asis Mazumdar, Indian SHP Project Planning and Development: A Review of DSS Tools, International Journal of Engineering Research & Technology 2(6), pp. 13861391, 2013 5. Priyabrata Adhikary, Pankaj Kr Roy, Asis Mazumdar, Fuzzy Logic based optimum penstock design: Elastic Water Column Theory Approach, ARPN Journal of Engineering and Applied Sciences 8(7), pp. 563-568, 2013 6. Priyabrata Adhikary, Susmita Kundu, Small Hydropower Project: Standard Practices, International Journal of Engineering Science & Advanced Technology 4(2), pp. 241-247, 2014 7. Priyabrata Adhikary, Susmita Kundu, Renovation Modernization Uprating & Life Extension: Optimal Solution For Small Hydropower Development, International Journal of Engineering Science & Advanced Technology 4(3), pp. 300-306, 2014 8. Priyabrata Adhikary, Pankaj Kr Roy, Asis Mazumdar, Multi-Dimensional Feasibility Analysis Of Small Hydropower Project in India: A Case Study, ARPN Journal of Engineering and Applied Sciences 9(1), pp. 80-84, 2014 9. Priyabrata Adhikary, Susmita Kundu, Pankaj Kr Roy, Asis Mazumdar, Optimum selection of Hydraulic Turbine Manufacturer for SHP:MCDA or MCDM Tools, World Applied Sciences Journal 28 (7), pp. 914-919, 2013 10. P.P. Sharma, S. Chatterji, B. Singh, MATLAB based simulation of components of small hydro-power plants, VSRD International Journal of Electrical, Electronics & Communication Engineering, 3(8), pp. 371-378, 2013
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