ABSTRACT: Ocean wave energy contains the largest energy density

Transcription

1 Deign and Modelling of Wave Energy Converter and Power Take-Off Sytem DESIGN AND MODELLING OF WAVE ENERGY CONVERTER AND POWER TAKE-OFF SYSTEM E. Chuah 1, K. Magawaran and M.Z. Haan 3 1 School of Engineering, Computing and Built Environment, KDU Penang Univerity College, Malayia. School of Engineering, Faculty Computing, Engineering and Technology, Aia Pacific Univerity of Technology and Innovation, Malayia 3 Faculty of Engineering Technology, Univeriti Teknikal Malayia Melaka, Malayia Correponding Author reanreh@gmail.com; Article Hitory: Received 16 Augut 017; Revied 5 October 017; Accepted 10 December 017 ABSTRACT: Ocean wave energy contain the larget energy denity amongt all renewable energy. In Malayia, the highet wave energy in the South China Sea i 1kW with maximum wave amplitude of meter. Thi paper preent the deign and modelling of wave energy converter and power take-off ytem that uitable for Malayia in order to obtain the highet output of electrical power. A point aborber made up of a floating buoy connected by a fibre rope i ued a wave energy converter. Linear permanent magnet generator ha been ued a the power-take-off ytem. Thi generator exploit directly the incoming ea wave vertical motion. Thi wave energy converter and power-take-off model have been developed and implement in Matlab. The model included wave energy, buoy water interaction, and linear generator. To extract highet wave energy, different parameter have been applied to the linear generator. Simulation reult are preented howing three effect of three different parameter; winding coil turn, magnetic field trength and tooth width of the tator. KEYWORDS: Wave Energy Harveting; Alternative Energy 1.0 INTR ODU CTION Since the Indutrial Revolution, human ue foil fuel uch a coal, natural ga, and petroleum to generate electrical energy. Continuou eissn: Special Iue idecon

2 Journal of Advanced Manufacturing Technology extraction of thee non-renewable energy reource will eventually caue the depletion of foil fuel [1]. Referring to the United State Environmental Protection Agency, 6% of greenhoue gae are emitted from energy upply []. It i conidered the larget ource of the global greenhoue ga emiion. The energy upply mentioned i the burning of foil fuel for the purpoe of electricity and heat generation. According to the Country Synthei Report On Urban Air Quality Management report, Malayian power plant emit about 10% nitrogen oxide, 60% ulphur dioxide and 40% of the particular matter in 004 [3]. Along with the growth of indutry and economy, the demand for electrical energy ha increaed [4]. To generate more electrical energy, the burning of foil fuel alo increaed. In Malayia, the electricity generation i produced through the contruction of open and combined cycle ga turbine, dual-fired ga or oil thermal power tation, coal-fired thermal power tation and hydroelectric power tation [5]. In 1999, a foil fuel that ued to generate electricity i 73.3% natural ga, 7.8% petroleum ga and 7.5% coal [5]. According to U.S Energy Information Adminitration report, petroleum and natural ga liquid are the primary energy ource conumed in Malayia followed by natural ga and coal [6]. Thi report alo tated that due to the economic development and population growth in Malayia, it reulted in ubtantially higher electricity generation landing at 134 billion kilowatt hour in 01 according to Malayia Energy Information Hub (MEIH) data [6]. In addition, foil fuel conumption in Malayia i quite high about 94.5% in the year 01 according to The World Bank data [6]. Foil fuel are non-renewable and have limited amount in the world. Becaue of the energy conumption increaing over the world, renewable energy ha been introduced. There are a few of renewable energy ource uch a olar, tidal and hydro. In Malayia, the mot commonly renewable energy i hydro and followed by olar and bioma. Although Malayia i located at the equator and ha a tropical climate, due to it eaonal rainfall variation in peninular Malayia, olar may not be the bet olution. In contrat, the hydroelectric power plant ha a lot of diadvantage. It may affect the 10 eissn: Special Iue idecon 016

3 Deign and Modelling of Wave Energy Converter and Power Take-Off Sytem environment and diturb the ecoytem and habitat of living being [8]. Amongt renewable energy ource, ocean wave contain the highet energy denity [9]. Wave energy ha a high availability factor compare with other reource, reource predictability, high power denity and low environmental and viual impact [9]. There are reearch and development program on wave energy in other countrie to invetigate the availability of wave power energy converion even though there i no any exploitation of wave energy to any ignificant extent in Malayia [10]. Ocean cover about more than 70% of the earth. A wave roll through the ocean, they contain kinetic energy. Thi kinetic energy can be harne and converted into electricity or power. There are varietie of way to convert thi energy into electricity. However, there are till many limit in harveting wave energy uch a high cot, low field experience, and limited technical kill [11]. Beide that, mot of the wave energy converter device are large in ize and complicated in deign. Uually, it i needed to be built offhore. Thu, reearch and engineering work have to be done to develop a reliable and cot efficient wave converter [1]. Thi project i conducted to tudy the feaibility of harveting wave energy uing modelling and imulation of a wave energy power generator. A wave energy generator coniting of a permanent magnet i mathematically modelled and imulated uing Matlab. Thi model i analyed by conducting a parametric tudy to deduce the optimum configuration in term of voltage, current and power production..0 DESIGN OF WAVE ENERGY CONVERTER The deign of the wave energy converter (WEC) require a floating buoy to be located on the ea urface connected by a rope to the linear permanent magnet generator. The floating buoy act a a point aborber device that aborb the wave energy. The location of thi floating buoy could be in the ocean horeline, near the hore or offhore [13]. In horeline, WEC can be eaily intalled and maintenance. They do not require any mooring and long length eissn: Special Iue idecon

4 Journal of Advanced Manufacturing Technology underwater electrical cable. However, thi device doe not experience high wave energy compared with other two location. Near the hore region i the tranition region between hallow and deep water. In thi region, WEC ha imilar advantage with horeline but experience higher powered wave than horeline. The offhore region will let WEC device experience more powerful wave in due to the deep water. In thi region, WEC require a mooring ytem to keep the device at the deired location [14]. Beide that, the tability of the floating buoy i alo conidered to make ure it reit overturning moment and can withtand variou external load uch a the wind, current and wave. In deigning, all the weight of the floating buoy are accounted for while calculating the centre of gravity [13]. The condition for the table equilibrium of a floating buoy required a retoring couple to return to it original poition following angular perturbation. A floating buoy i conidered table when all the reultant force acting on it i zero. In addition, the ize of the floating buoy need to be determined to increae the performance of the floating buoy. The ize of the floating buoy hould be much maller than the incoming wavelength o that it will capture the wave energy effectively [14]. The teepne of the incoming wave i very important a it may affect the output power and the lifepan if the floating buoy. If the diameter of the floating buoy i larger than or equal with the teepne of wave, the floating buoy could be ubmerged more than it i required and ome part could be damaged. Thi will affect the output power. So, the floating device hould be mall in ize o that it will be able to operate in mot of the condition. On the other hand, to obtain optimal output power from the floating buoy, the incident of wave frequencie mut be cloer to or correpond to the natural frequency of the floating buoy. The natural frequencie of the floating buoy are calculated by conidering the total ma of the ytem and pring contant. The natural frequencie are then tuned by varying the ma of the ytem and pring contant. A mooring ytem maintain the floating buoy at the deired poition [15]. There are three categorie of material that ued in mooring: metal (wire or chain), ynthetic material (nylon line), and natural non-metallic. The common material ued for energy converion i a 1 eissn: Special Iue idecon 016

5 Deign and Modelling of Wave Energy Converter and Power Take-Off Sytem chain, wire rope, and fiber rope. Thee material will provide optimum performance for the floating buoy in a wide range of water depth. The chain i the heaviet, ha highet break trength and elaticity while fiber rope ha light weight, lower break trength and elaticity compare with chain. The choice for chooing thi material depend on the water depth, the eabed material and lope and the cot [15]. 3.0 MATHEMATICAL MODELLING Ocean wave motion are normally generated by the different type of force uch a bodie moving on the urface of the ocean, wind puh the ea urface and create different preure between the air and water. The difference of ditance between earth and the moon will alo generate wave. The important parameter that decribe wave are wavelength, wave amplitude, period, and water depth. Higher wave energy can be obtained in deep water a compared to hallow water. Thi i becaue ocean wave travel lowly in hallow water with mall wavelength. Wave fluctuation that caue by only one frequency in vertical direction can be preented a: x Ain wt (1) where AA i wave amplitude and ωω i angular frequency. In deep water, approximation expreion for wave power, PP wwwwwwww can be decribed a: pg H T P wave 64 () Here ρρ i the eawater denity, gg i gravitational acceleration, HH i wave ignificant height and TT i wave period. Table 1: Northeat monoon wave data [8] Northeat Value monoon Wave amplitude.0 m Wave time period Wavelength m eissn: Special Iue idecon

6 Journal of Advanced Manufacturing Technology Referring to wave data given by Table 1, the approximation maximum wave power that Malayia can experience by uing the Equation i 11.77kW. According to Malayian Meteorological Department, Malayia experience northeat monoon and outheat monoon. The overall highet wave height i during northeat monoon in the South China Sea. The potential energy of wave will lift the floating buoy a illutrated in Figure 1. Thi floating buoy i the main converter that convert wave energy into kinetic energy to move the tranlator that mounted with a permanent magnet. The total force acting on the floating buoy conit of buoyancy force FF bb, drag force FF dd, radiated force FF rr, excitation force FF ee, pring force FF and generator force FF gg. The buoy movement i then controlled by the following equation: M z = F F F F F F (3) b d r e g where MM i the total ma of buoy-tranlator ytem and zz i the acceleration. Figure 1: Schematic diagram of wave energy converter Buoyant force i the upward force that acting on the buoy when the buoy i fully or partially ubmerged in the water. The buoyant force can then be calculated a: F S z (4) b b 14 eissn: Special Iue idecon 016

7 Deign and Modelling of Wave Energy Converter and Power Take-Off Sytem The SS bb i hydrotatic tiffne and zz i vertical diplacement, S b ga (5) w where ρρ i eawater denity, gg i gravitational acceleration, and AA ww i the area of floating buoy. Drag force alo known a fluid reitance i the force that acting oppoite to the relative motion of the floating buoy with repect to the urrounding fluid. Drag force can be expreed a: F d 1 C A z (6) d w where, ρρ i eawater denity, CC dd i drag coefficient and zz i velocity. Radiated force appear due to the wave which i radiated by the buoy motion itelf in the abence of incident wave. Radiated force can define a: F r m z R z (7) r r Here mm rr i added ma, RR rr i radiated reitance and can be computed a: m r m (8) r m a 3 3 R r r (9) where mm mm i ma of the buoy, ωω i the angular frequency of the incident wave, μμ rr and εε rr are coefficient. Excitation force i the wave progre in the poitive x-direction to the floating buoy which can move in the urge, heave and pitch motion. For implicity, the excitation force can be calculated a follow: F e g a x (10) eissn: Special Iue idecon

8 Journal of Advanced Manufacturing Technology in which κκ i non-dimenion excitation force which depend on kkkk (kk = ππ/λλ), λλ i the wavelength. A pring that connect the floating buoy to the bottom tructure function a an energy toring mechanim. When the buoy i lifted by a wave, ome energy i converted into electrical energy while ome energy i tored in pring. When the buoy move downward, the tored energy i converted into electrical energy. F k z (11) where kk i the pring contant and zz i vertical diplacement. The electromagnetic force (emf) produced by the linear permanent magnet generator in one phae can compute from the equation below: E i d im dz (1) dz dt where λλ iiii i the flux linkage in phae ii due to permanent magnet and zz i vertical diplacement. The flux linkage can be expreed a: im N co z (13) i i w p where NN ii i number of turn in phae- ii, ii i maximum flux and ww pp i pole pitch. Therefore, the generator force that provided by the linear permanent magnet generator which oppoing the movement of the buoy can be given a: F g N in z i (14) i i w i p where ii ii i the current in the phae- ii. The per-phae inductance, LL of the generator can be computed by: 0 p w L N p geff 6 l w k Ni (15) 16 eissn: Special Iue idecon 016

9 Deign and Modelling of Wave Energy Converter and Power Take-Off Sytem where μμ 0 i air permeability, ll i tator length, kk ww i winding factor, NN pp i the number of pole and gg eeeeee i effective air gap length and can be calculated from: geff Kcg 1 (16) where gg 1 i air gap length and KK cc i the Carter coefficient and i calculated from the equation: K c t Tt 5g1 b 5g b b (17) T 1 where bb i the lot width and TT tt i the tooth pitch and can be calculate from: T t b b (18) t where bb tt i the tooth width. The generator phae reitance i: R i p fil N l wp cu (19) N h b k where ρρ cccc i copper reitivity, h i lot length, kk i copper filling factor. The output phae current, II pph i then calculated from equation: I ph v ph (0) R L where VV pph i the output phae voltage. Therefore, the three-phae output power that produced by the linear permanent magnet generator can then be calculated a P 3V I (1) out line line where II llllllll = II pph and VV llllllll can be calculated a: Vline 3V ph () eissn: Special Iue idecon

10 Journal of Advanced Manufacturing Technology 4.0 OUTPUT POWER DUE TO VARIOUS PARAMETERS Three different parameter are tudied via imulation to obtain the highet electrical output power. The parameter are the number of winding coil turn, magnetic field trength and tooth width of the tator. The default value for thee parameter are 000, 0.55T and 75mm repectively. One of the value i changed while the other remain a contant. The range choen for thee parameter are o that the wave generator ize remain realitic and economic. 4.1 Number of winding coil turn The imulation i carried out with the number of winding coil turn i increaed from 500 to Baed on Figure, it how that the output phae voltage increae and output phae current decreae a winding turn increaed. A the winding turn increaed, the inductance i alo increaed. Thi reulted in more voltage being induced and current i decreaed. Overall, the output voltage i directly proportional the number of turn of the coil and the output power alway remain unchanged. Figure : Voltage, Current and Power v No. of turn 4. Magnetic field trength The econd imulation i carried out to evaluate the optimum magnetic field trength for the purpoe of obtaining higher output power. Thi magnetic field trength of the magnet i et from 0.45T to 0.7T. From the Figure 3, it i oberved that the phae output voltage, 18 eissn: Special Iue idecon 016

11 Deign and Modelling of Wave Energy Converter and Power Take-Off Sytem phae output current, and output power i increaed linearly with the increment value of magnetic field trength. The reaon i due to the tronger magnetic field denity that produced a higher induced voltage when more magnetic flux cut through the winding coil. Thi will reult in a greater current flow through the coil. Therefore, output power increae a voltage and current increae. Overall, it can be concluded that output phae voltage, phae current, and output power i directly proportional to the magnetic field trength. Figure 3: Voltage, Current and Power v Magnetic Field Strength 4.3 Tooth width of tator The third imulation i carried out to determine the output power with different tooth width of the tator. The winding coil are tied in the tooth width of the tator. By changing the tooth width diameter, the winding coil diameter alo changed. In the imulation, the tooth width diameter i increaed from 65 mm to 85 mm. Figure 4: Voltage, Current and Power v Tooth width of tator eissn: Special Iue idecon

12 Journal of Advanced Manufacturing Technology Baed on Figure 4, it can be een that output power and phae current decreae a tooth width of tator increaed. However, the value of phae voltage remain contant at 5V with the change of tooth width. Thi how that the value of tooth width mut be a mall a poible. By decreaing tooth width of the tator, larger contact area between teeth and the permanent magnet allow the output performance to be increaed. However, the tooth width hould not be too mall a it may affect the carrying of magnetic flux with the coil. Anyway it can be concluded that output power decreae gradually with the increae of tooth width. 5.0 CONCL U S ION In concluion, the preent work meet the expectation to be able to imulate the optimum configuration of the wave energy power generator in term of voltage, current and power production. Through the parametric analyi conducted it can be deduced that the winding coil of 3500, magnetic field trength of 0.7T and tooth width of 65 mm produced the highet output power i W with an output phae voltage of 7.5 V and an output phae current of 9.45 A. A CK NOWLEDGMENTS The third author would like to thank Univeriti Teknikal Malayia Melaka (UTeM) for the continuou upport and reearch funding to hi reearch. R EF ER ENCES [1] N. Muda and J.P. Tey, On prediction of depreciation time of foil fuel in Malayia, Journal of Mathematic and Statitic, vol. 8, no. 1, pp , 01. [] M.M. Ahmed and M. Sulaiman, Deign and proper izing of olar energy cheme for electricity production in Malayia, in National Power and Energy Conference, 003, pp eissn: Special Iue idecon 016

13 Deign and Modelling of Wave Energy Converter and Power Take-Off Sytem [3] M.B. Farriz, A.N. Azmi, N.A.M. Said, A. Ahmad and K.A. Baharin, A tudy on the wind a a potential of renewable energy ource in Malayia, in International Conference on Electrical Engineering / Electronic Computer Telecommunication and Information Technology, Chiang Mai Thailand, 010, pp [4] N. Raman, I. Huein and K. Palaniamy, Micro hydro potential in Wet Malayia, in The 3rd International Conference on Energy and Environment, Melaka, Malayia, 009, pp [5] S. K. Cheng and G. Lalchand, A review on utainable power generation in Malayia to 030: Hitorical perpective, current aement, and future trategie, Renewable and Sutainable Energy Review, vol. 9, pp , 014. [6] N.H. Samrat, N. Ahmad and Z. Taha, Propect of wave energy in Malayia, in IEEE 8th International Power Engineering and Optimization Conference, Langkawi, Malayia, 014, pp [7] T.J. Hammon, Tidal power in The UK and worldwide to reduce greenhoue ga emiion, International Journal of Engineering Buine Management, vol. 3, no., pp. 16-8, 008. [8] M. Richter, M.E. Magana, O. Sawodny and T.K.A. Brekken, Power optimiation of a point aborber wave energy converter by mean of linear model predictive control, IET Renewable Power Generation, vol. 8, no., pp , 014. [9] A. M. Muzathink, W.B. Wan Nik, M.Z. Ibrahim and K.B. Samo, Wave energy potential of peninular Malayia, ARPN Journal of Engineering and Applied Science, vol. 5, no. 7, pp.11-3, 010. [10] O. Yaakob, T.A. Rahid, T. Mohd Ariff, A. Mukti and M. Afifi, Propect for ocean energy in Malayia, in International conference on energy and environment, 006, pp [11] J.L. Vilatte, Implementing agreement on ocean energy ytem, in Ocean Energy Sytem Annual Report, Libon, Portugal, 013. [1] H.Y. Chong, W.H. Lam, Ocean renewable energy in Malayia: The potential of the Strait of Malacca, Renewable and Sutainable Energy Review, vol. 3, pp , 013. [13] H.F. Yu, Y.L. Zhang and S.M. Zheng, Numerical tudy on the performance of a wave energy converter with three hinged bodie, Renewable Energy, vol. 99, pp , 016. eissn: Special Iue idecon 016 1

14 Journal of Advanced Manufacturing Technology [14] M. Faizal, M.R. Ahmed and Y.H. Lee, A deign outline for floating point aborber wave energy converter, Advance in Mechanical Engineering, vol. 6, pp. 1-18, 014. [15] N.M. Tom, M.J. Lawon, Y.H. Yu and A.D. Wright, Development of a nearhore ocillating urge wave energy converter with variable geometry, Renewable Energy, vol. 96, pp , 016. eissn: Special Iue idecon 016