Energy Comparison of MPPT Techniques Using Cuk Converter

Transcription

1 Internatonal Journal of Innoate Research n Adanced Engneerng (IJIRAE) ISSN: Volume 1 Issue 6 (July 214) Energy Comparson of MPPT Technques Usng Cuk Conerter R.B.Wankhede 1 PROF.U.B.Vadya 2 1 Student of M.Tech(EMS), RCERT, Chandrapur. 2 Professor, Electrcal Department, RCERT, Chandrapur AbstractIn ths paper the energy comparson of two MPPT, P&O and Incremental conductance s done usng cuk conertor. For comparson such as oltage, current and power output for each dfferent combnaton has been recorded. MATLAB smulnk tools hae been used for performance ealuaton on energy pont. Key wordsmaxmum power pont trackng MPPT, photooltac cell PV, P&O, ncremental conductance IC, CUK conertor I.INTRODUCTION Photooltac (PV) generaton s becomng ncreasngly mportant as a renewable source snce t offers many adantage such as ncurrng no fuel cost, not beng polluted, requrng lttle mantenance, and emttng no nose among others.[1] PV module stll hae relately low conerson effcency, therefore, controllng maxmum power pont trackng (MPPT) for the solar array s essental n a PV system. The optmum operatng changes wth solar radaton and cell temperature. In general, there s a unque pont on VI or VP characterstc cure, called maxmum power pont (MPP) at whch entre PV system operates wth maxmum effcency and produces ts maxmum power output.[2] Therefore Maxmum Power Pont Trackng (MPPT) technques are needed to mantan the PV array operatng pont at ts MPP.A arety of maxmum power pont trackng (MPPT) are deeloped. These technques ary between then n many aspects ncludng smplcty, conergence, speed, hardware mantenance, sensor requred, cost range effecteness. Perterb and obserance[3] and ncreamental conductance technque[4] usng cuk conertor wth resste load s studed n ths paper. II.PV EQUIVALENT CIRCUIT Solar cells are connected n seres and parallel to set up the solar array. Solar cell wll produce dc oltage when t s exposed to sunlght. Fg.1 shows the equalent crcut model for a solar cell. Solar cell can be regarded as a nonlnear current source.[5] Its generated current depends on the characterstc of materal, age of solar cell, rradaton and cell temperature. Fg.1:Equalent crcut model for a solar cell III. CUK CONVERTER When proposng an MPP tracker, the major job s to choose and desgn a hghly effcent conerter, whch s supposed to operate as the man part of the MPPT. The effcency of swtchmode dc dc conerters s wdely dscussed n [7]. Most swtchngmode power supples are well desgned to functon wth hgh effcency. Among all the topologes aalable, both Cuk and buck boost conerters prode the opportunty to hae ether hgher or lower output oltage compared wth the nput oltage. Although the buck boost confguraton s cheaper than the Cuk one, some dsadantages, such as dscontnuous nput current, hgh peak currents n power components, and poor transent response,make t less effcent.on the other hand the Cuk conertor has low swtchng losses and the heghest effcency amond non solated dcdc conertor. It can also prode a better outputcurrent characterstc due to the nductor on the output stage. Thus, the Cuk confguraton s a proper conerter to be employed n desgnng the MPPT. Fgs. 2 and 3 show a Cuk conerter and ts operatng modes, whch s used as the power stage nterface between the PV module and the load. The Cuk conerter has two modes of operaton. The frst mode of operaton s when the swtch s closed (ON), and t s conductng as a short crcut. In ths mode, the capactor releases energy to the output. The equatons for the swtch conducton mode are as follows: L1=Vg (1) L 2 = 1 2 (2) 214, IJIRAE All Rghts Resered Page 277

2 Internatonal Journal of Innoate Research n Adanced Engneerng (IJIRAE) ISSN: Volume 1 Issue 6 (July 214) c 1 = 2 (3) c 2 = 2 2/R (4) make t less effcent. On the other hand, the Cuk conerter has low swtchng losses and the hghest effcency among non solated dc dc conerters. Fg. 2 Electrcal crcut of the Cuk conerter used as the PV powerstage nterface Fg.3.Cuk conerters wth (a) swtch ON and (b) swtch OFF On the second operatng mode when the swtch s open (OFF), the dode s forwardbased and conductng energy to the output. Capactor C1 s chargng from the nput. The equatons for ths mode of operaton are as follows: L1 =Vg 1 (5) L2= 2 (6) c 1 = 1 (7) c 2 = 2 2/R (8) The prncples of Cuk conerter operatng condtons state that the aerage alues of the perodc nductor oltage and capactor current waeforms are zero when the conerter operates n steady state. The relatons between output and nput currents and oltages are gen n the followng: VO/Vn= (D/1 ) (9) In/Io= ( /1 D) (1) IV.PERTURB AND OBSERVE (P&O) In ths algorthm a slght perturbaton s ntroduce system [8]. Ths perturbaton causes the power of the solar module changes. If the power ncreases due to the perturbaton then the perturbaton s contnued n that drecton [8]. After the peak power s reached the power at the next nstant decreases and hence after that the perturbaton reerses. When the steady state s reached the algorthm oscllates around the peak pont. In order to keep the power araton small the perturbaton sze s kept ery small. A PI controller then acts mong the operatng pont of the module to that partcular oltage leel. It s obsered that there some power loss due to ths perturbaton also the fals to track the power under fast aryng atmospherc condtons. But stll ths algorthm s ery popular and smple. Fg. 4: Graph Power ersus Voltage for Perturb and Obsere Algorthm [3] 214, IJIRAE All Rghts Resered Page 278

3 Internatonal Journal of Innoate Research n Adanced Engneerng (IJIRAE) ISSN: Volume 1 Issue 6 (July 214) Fg. 5: Flow chart of the Perturb and Obsere Algorthm [3] V.INCREAMENTAL CONDUCTANCE (IC) The dsadantage of the perturb and obsere method to track the peak power under fast aryng atmospherc condton s oercome by IC method [3]. Fg.6: Graph Power ersus Voltage for IC algorthm Fg 7 :Flow chart of ncremental conductance method 214, IJIRAE All Rghts Resered Page 279

4 Internatonal Journal of Innoate Research n Adanced Engneerng (IJIRAE) ISSN: Volume 1 Issue 6 (July 214) The IC can determne that the MPPT has reached the MPP and stop perturbng the operatng pont. If ths condton s not met, the drecton n whch the MPPT operatng pont must be perturbed can be calculated usng the relatonshp between dl/dv and I/V [9 Ths relatonshp s dered from the fact that dp/dv s negate when the MPPT s to the rght of the MPP and poste when t s to the left of the MPP. Ths algorthm has adantages oer P&O n that t can determne when the MPPT has reached the MPP, where P&O oscllates around the MPP. Also, ncremental conductance can track rapdly ncreasng and decreasng rradance condtons wth hgher accuracy than perturb and obsere [3]. One dsadantage of ths algorthm s the ncreased complexty when compared to P&O [3]. VI. GRAPHICAL ENVIRONMENT MATLAB SIMULINK ENVIRONMENT C ontnuous powergu V To Workspace1 Scope6 D Vref P To Workspace PWM Generator V RMS4 Scope2 PWM V Product Scope4 Step Saturaton ISO PVG1 Current Measurement V V V Cuk V Seres RLC Branch Current Measurement1 Voltage Measurement Abs Scope InRMS Voltage Measurement1 RMS1 Scope3 Abs1 I V I Vref To Workspace2 MPPT Scope8 Scope1 Scope5 RMS2 RMSIn Product1 V1 To Workspace4 P1 To Workspace3 Fg 8: Smulnk model of Incremental conductance MPPT wth resste load. InRMS Dscrete, Ts = 5e6 s. pow ergu Dscrete RMS alue6 p I nrms Product1 Dscrete RMS al ue5 pp V1 Vm1 I nrms Dscrete RMS al ue4 p Abs1 Dscrete RMS al ue3 To Workspace P1 Step Saturaton V ISO V PVG Cm1 PWM V V cuk V V Cm RL Vm Product Abs InRMS Dscrete RMS alue1 To Workspace1 p Saturaton1 d In1 Out 1 Out 2 Abs2 Dscrete RMS al ue2 I1 To Workspace2 Subsystem >= S/H In Compare To Constant2 Subtract Sample and Hold1 Transport Delay Fg 9: Smulnk model of PO MPPT wth resste load 214, IJIRAE All Rghts Resered Page 28

5 Internatonal Journal of Innoate Research n Adanced Engneerng (IJIRAE) ISSN: Volume 1 Issue 6 (July 214) Contnuo us powergu D Vref Constant1.465 P To Workspace RMS5 Scope2 PWM Generator V PWM V Product Power Step Saturaton ISO PVG1 Current Measurement V V V Cuk V Seres RLC Branch C urrent Measurement1 Voltage Measurement Abs Scope Voltage Measurement1 RMS1 Scope3 V To Workspace1 Abs1 I To Workspace2 Scope1 Scope5 RMS2 Product1 RMS In Fg 1: Smulnk model of wth ought IC and P&O MPPT wth resste load VII. RESULT Result of comparson of o/p current, oltage and power wth and wthout Perturb and obsere method and Incremental conductance method s shown n fgure below current oltage power tme x 1 4 Fg. 11. Comparson dagram of o/p current, oltage & power wthout P&O and Incremental conductance method 214, IJIRAE All Rghts Resered Page 281

6 Internatonal Journal of Innoate Research n Adanced Engneerng (IJIRAE) ISSN: Volume 1 Issue 6 (July 214) current oltage power tme x 1 5 Fg. 12. Comparson dagram of o/p current, oltage & power wth Incremental conductance method current , IJIRAE All Rghts Resered Page 282

7 Internatonal Journal of Innoate Research n Adanced Engneerng (IJIRAE) ISSN: Volume 1 Issue 6 (July 214) 25 2 oltage power Fg. 14: Comparson dagram of o/p current, oltage & power wth perturb & obsere method VIII. CONCLUSION Ths paper has presented a comparson of two most popular MPPT controller, Perturb and Obsere Controller wth Incremental Conductance Controller. One smple solar panel that has standard alue of nsolaton and temperature has been ncluded n the smulaton crcut. From all the cases, the best controller for MPPT s ncremental conductance controller. Ths controller ges a better output alue for cuk conerter. REFERENCES [1] Sohan Lal, Rohtash Dhman, Mr.S.K.Snha, Analyss Dfferent MPPT Technques for Photooltac System Internatonal Journal of Engneerng and Innoate Technology (IJEIT) Volume 2, Issue 6, December 212 [2] Jay Patel, Vshal sheth, Gaurang Sharma, Desgn & Smulaton Of Photooltac System Usng Increamental MPPT Algorthm Internatonal Journal of Adanced Research n Electrcal, Electroncs and Instrumentaton Engneerng Vol. 2, Issue 5, May 213 [3] Harul Nssah Zanudn, Saad Mekhlef, Comparson Study of Maxmum Power Pont Tracker Technques for PV Systems Proceedngs of the 14th Internatonal Mddle East Power Systems Conference (MEPCON 1), Caro Unersty, Egypt, December 1921, 21, Paper ID 278. [4] Saraana Selan. D, Modelng and Smulaton of Incremental Conductance MPPT Algorthm for Photooltac Applcatons Internatonal Journal of Scentfc Engneerng and Technology (ISSN : ) Volume No.2, Issue No.7, pp : July 213 [5] M.Lokanadham, K.Vjaya Bhaskar, Incremental Conductance Based Maxmum Power Pont Trackng (MPPT) for Photooltac System Internatonal Journal of Engneerng Research and Applcatons (IJERA), Vol. 2, Issue 2,MarApr 212, pp [6] Dya Teja Reddy Challa, I. Raghaendar, Implementaton of Incremental Conductance MPPT wth Drect Control Method Usng Cuk Conerter, Internatonal Journal of Modern Engneerng Research (IJMER),Vol.2, Issue.6, NoDec. 212 pp ISSN: [7] R.J. Wa, W.H. Wang and C.Y. Ln, Hghperformance standalone Photooltac generaton system, IEEE Trans. Ind. Electron. ol. 55, no. 1, pp , Jan. 28. [8] Ch.Kran Kumar, T.Dnesh, S.Ganesh Babu, Desgn and Modellng of PV system and Dfferent MPPT algorthms Internatonal Journal of Engneerng Trends and Technology (IJETT) Volume 4 Issue 9 Sep , IJIRAE All Rghts Resered Page 283