Research Paper.rar_matlab simulink_hybrid

<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8"> <meta name="generator" content="pdf2htmlEX"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <link rel="stylesheet" href="https://static.pudn.com/base/css/base.min.css"> <link rel="stylesheet" href="https://static.pudn.com/base/css/fancy.min.css"> <link rel="stylesheet" href="https://static.pudn.com/prod/directory_preview_static/626419ba4f8811599e3883f5/raw.css"> <script src="https://static.pudn.com/base/js/compatibility.min.js"></script> <script src="https://static.pudn.com/base/js/pdf2htmlEX.min.js"></script> <script> try{ pdf2htmlEX.defaultViewer = new pdf2htmlEX.Viewer({}); }catch(e){} </script> <title></title> </head> <body> <div id="sidebar" style="display: none"> <div id="outline"> </div> </div> <div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626419ba4f8811599e3883f5/bg1.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">Optimization in microgrids with hybrid energy systems – A review</div><div class="t m0 x1 h3 y2 ff1 fs1 fc0 sc0 ls0 ws0">A. Hina Fathima</div><div class="t m1 x2 h4 y3 ff3 fs2 fc1 sc0 ls0 ws0">n</div><div class="t m2 x3 h3 y2 ff1 fs1 fc0 sc0 ls0 ws0">, K. Palanisamy</div><div class="t m3 x1 h5 y4 ff4 fs3 fc0 sc0 ls0 ws0">School of Electrical Engineering, VIT University, Vellore, India</div><div class="t m4 x1 h6 y5 ff5 fs4 fc0 sc0 ls1 ws0">article info</div><div class="t m3 x1 h5 y6 ff4 fs3 fc0 sc0 ls0 ws0">Article history:</div><div class="t m3 x1 h7 y7 ff1 fs3 fc0 sc0 ls0 ws0">Received 25 April 2014</div><div class="t m3 x1 h7 y8 ff1 fs3 fc0 sc0 ls0 ws0">Received in revised form</div><div class="t m3 x1 h7 y9 ff1 fs3 fc0 sc0 ls0 ws0">12 November 2014</div><div class="t m3 x1 h7 ya ff1 fs3 fc0 sc0 ls0 ws0">Accepted 19 January 2015</div><div class="t m3 x1 h5 yb ff4 fs3 fc0 sc0 ls0 ws0">Keywords:</div><div class="t m3 x1 h7 yc ff1 fs3 fc0 sc0 ls0 ws0">Microgrids</div><div class="t m3 x1 h7 yd ff1 fs3 fc0 sc0 ls0 ws0">Hybrid energy systems</div><div class="t m3 x1 h7 ye ff1 fs3 fc0 sc0 ls0 ws0">Solar power</div><div class="t m3 x1 h7 yf ff1 fs3 fc0 sc0 ls0 ws0">Wind power</div><div class="t m3 x1 h7 y10 ff1 fs3 fc0 sc0 ls0 ws0">Energy storage systems</div><div class="t m3 x1 h7 y11 ff1 fs3 fc0 sc0 ls0 ws0">Optimization</div><div class="t m4 x4 h6 y5 ff5 fs4 fc0 sc0 ls2 ws0">abstract</div><div class="t m4 x4 h8 y12 ff1 fs5 fc0 sc0 ls0 ws0">Fast depleting fossil fuels and the growing awareness for environmental protection have led us to the</div><div class="t m4 x4 h8 y13 ff1 fs5 fc0 sc0 ls0 ws0">energy crisis. Hence, efforts are being made by researchers to investigate new ways to extract energy</div><div class="t m4 x4 h8 y14 ff1 fs5 fc0 sc0 ls0 ws0">from renewable sources. ‘Microgrids’ with Distributed Generators (DG) are being implemented with</div><div class="t m4 x4 h8 y15 ff1 fs5 fc0 sc0 ls0 ws0">renewable energy systems. Optimization methods justify the cost of investment of a microgrid by</div><div class="t m4 x4 h8 y16 ff1 fs5 fc0 sc0 ls0 ws0">enabling economic and reliable utilization of the resources. This paper strives to bring to light the</div><div class="t m4 x4 h8 y17 ff1 fs5 fc0 sc0 ls0 ws0">concept of Hybrid Renewable Energy Systems (HRES) and state of art application of optimization tools</div><div class="t m4 x4 h8 y18 ff1 fs5 fc0 sc0 ls0 ws0">and techniques to microgrids, integrating renewable energies. With an extensive literature survey on</div><div class="t m4 x4 h8 y19 ff1 fs5 fc0 sc0 ls0 ws0">HRES, a framework of diverse objectives has been outlined for which optimization approaches were</div><div class="t m4 x4 h8 y1a ff1 fs5 fc0 sc0 ls0 ws0">applied to empower the microgrid. A review of modelling and applications of renewable energy</div><div class="t m4 x4 h8 y1b ff1 fs5 fc0 sc0 ls0 ws0">generation and storage sources is also presented.</div><div class="t m4 x5 h8 y1c ff3 fs5 fc0 sc0 ls0 ws0">& 2015 Elsevier Ltd. All rights reserved.</div><div class="t m5 x1 h9 y1d ff6 fs6 fc0 sc0 ls0 ws0">1. Introduction</div><div class="t m5 x6 ha y1e ff1 fs6 fc0 sc0 ls0 ws0">Microgrids combine different energy sources in the best possible</div><div class="t m5 x1 ha y1f ff1 fs6 fc0 sc0 ls0 ws0">manner to cater to local loads with the ability to operate either</div><div class="t m5 x1 ha y20 ff1 fs6 fc0 sc0 ls0 ws0">connected or disconnected with the utility grid. They can be viewed</div><div class="t m5 x1 ha y21 ff1 fs6 fc0 sc0 ls0 ws0">as a controllable subsystem generating power from the Distributed</div><div class="t m5 x1 ha y22 ff1 fs6 fc0 sc0 ls0 ws0">Energy Resources (DER) which are mostly renewable in nature. The</div><div class="t m5 x1 ha y23 ff1 fs6 fc0 sc0 ls0 ws0">microgrids were ﬁrst developed by the Consortium for Electric</div><div class="t m5 x1 ha y24 ff1 fs6 fc0 sc0 ls0 ws0">Reliability Technology Solutions (CERTS). They have, in the recent</div><div class="t m5 x1 ha y25 ff1 fs6 fc0 sc0 ls0 ws0">past, enhanced the ﬂexibility of the power systems by improving</div><div class="t m5 x1 ha y26 ff1 fs6 fc0 sc0 ls0 ws0">the reliability of the power delivery. Microgrid, though it has been</div><div class="t m5 x1 ha y27 ff1 fs6 fc0 sc0 ls0 ws0">in discussion lately, is an old concept. If we notice the early</div><div class="t m5 x1 ha y28 ff1 fs6 fc0 sc0 ls0 ws0">developments of the electrical industry, all power systems have</div><div class="t m5 x1 ha y29 ff1 fs6 fc0 sc0 ls0 ws0">been isolated. The world's ﬁrst public power station was a steam-</div><div class="t m5 x1 ha y2a ff1 fs6 fc0 sc0 ls0 ws0">powered electricity generating station initiated by Thomas Edison</div><div class="t m5 x1 ha y2b ff1 fs6 fc0 sc0 ls0 ws0">in London in the years and later at Manhattan in 1882. He proposed</div><div class="t m5 x1 ha y2c ff1 fs6 fc0 sc0 ls0 ws0">the generation of power locally using DC generators, but there were</div><div class="t m5 x1 ha y2d ff1 fs6 fc0 sc0 ls0 ws0">no means available for conversion of voltage to the desired levels.</div><div class="t m5 x1 ha y2e ff1 fs6 fc0 sc0 ls0 ws0">Microgrids share a lot of similarities with these early systems as</div><div class="t m5 x1 ha y2f ff1 fs6 fc0 sc0 ls0 ws0">they too are generated locally with dedicated loads. Hence we state</div><div class="t m5 x1 ha y30 ff1 fs6 fc0 sc0 ls0 ws0">that the early isolation strategies are now revisited in the form of</div><div class="t m5 x1 ha y31 ff1 fs6 fc0 sc0 ls0 ws0">microgrids which have the distinct capability of incorporating grid</div><div class="t m5 x1 ha y32 ff1 fs6 fc0 sc0 ls0 ws0">connections as and when necessary.</div><div class="t m5 x6 ha y33 ff1 fs6 fc0 sc0 ls0 ws0">Extreme centralization has led to a lot of drawbacks such as</div><div class="t m5 x1 ha y34 ff1 fs6 fc0 sc0 ls0 ws0">limitations on the use of non-renewable fuels, expansion of existing</div><div class="t m5 x1 ha y35 ff1 fs6 fc0 sc0 ls0 ws0">networks, reducing congestion on existing lines and threats from</div><div class="t m5 x7 ha y36 ff1 fs6 fc0 sc0 ls0 ws0">malicious entities. An entire nation's communication to infrastruc-</div><div class="t m5 x7 ha y37 ff1 fs6 fc0 sc0 ls0 ws0">ture; utilities to even defence depend on its electric power. Hence,</div><div class="t m5 x7 ha y38 ff1 fs6 fc0 sc0 ls0 ws0">pooling of the entire control of power in one place makes it an</div><div class="t m5 x7 ha y39 ff1 fs6 fc0 sc0 ls0 ws0">attractive target for malicious attacks. These factors combined with</div><div class="t m5 x7 ha y3a ff1 fs6 fc0 sc0 ls0 ws0">an inclination to promote the use of renewable energy have led the</div><div class="t m5 x7 ha y3b ff1 fs6 fc0 sc0 ls0 ws0">development of distribution generation. The concept of having</div><div class="t m5 x7 ha y3c ff1 fs6 fc0 sc0 ls0 ws0">the DER allows the decentralization of the power generation and</div><div class="t m5 x7 ha y3d ff1 fs6 fc0 sc0 ls0 ws0">the storage. In fact, the deﬁnition for DER includes both the</div><div class="t m5 x7 ha y3e ff1 fs6 fc0 sc0 ls0 ws0">generators and the energy storage technologies. The generation</div><div class="t m5 x7 ha y3f ff1 fs6 fc0 sc0 ls0 ws0">facilities are called Distributed Generators (DG) and they include a</div><div class="t m5 x7 ha y40 ff1 fs6 fc0 sc0 ls0 ws0">small power generating units which may be placed at an isolated</div><div class="t m5 x7 ha y41 ff1 fs6 fc0 sc0 ls0 ws0">site not connected to the power grid or the site of the customer [1].</div><div class="t m5 x7 ha y42 ff1 fs6 fc0 sc0 ls0 ws0">The microgrid is connected to the utility grid through a Point of</div><div class="t m5 x7 ha y43 ff1 fs6 fc0 sc0 ls0 ws0">Common Coupling (PCC). Microgrids provide a good platform to</div><div class="t m5 x7 ha y44 ff1 fs6 fc0 sc0 ls0 ws0">realize the DGs to harness the green energy. Since they can be</div><div class="t m5 x7 ha y45 ff1 fs6 fc0 sc0 ls0 ws0">viewed as a subsystem of power generation and associated loads,</div><div class="t m5 x7 ha y46 ff1 fs6 fc0 sc0 ls0 ws0">their local control is easier, thus eliminating the expensive costs and</div><div class="t m5 x7 ha y47 ff1 fs6 fc0 sc0 ls0 ws0">hazards of central dispatch centres. DGs include much electricity</div><div class="t m5 x7 ha y48 ff1 fs6 fc0 sc0 ls0 ws0">generating technologies of which some are the conventional inter-</div><div class="t m5 x7 ha y49 ff1 fs6 fc0 sc0 ls0 ws0">nal combustion (IC) engines and gas turbines. Whereas, the other</div><div class="t m5 x7 ha y4a ff1 fs6 fc0 sc0 ls0 ws0">renewable systems like photovoltaics, wind turbines and fuel-cells</div><div class="t m5 x7 ha y4b ff1 fs6 fc0 sc0 ls0 ws0">are also included. Some renewable sources are capable of generat-</div><div class="t m5 x7 ha y4c ff1 fs6 fc0 sc0 ls0 ws0">ing a DC voltage and hence they have to be interfaced with the AC</div><div class="t m5 x7 ha y4d ff1 fs6 fc0 sc0 ls0 ws0">distribution system using the power electronic interfaces. They have</div><div class="t m5 x7 ha y4e ff1 fs6 fc0 sc0 ls0 ws0">many signiﬁcant advantages such as lower maintenance costs,</div><div class="t m5 x7 ha y4f ff1 fs6 fc0 sc0 ls0 ws0">emissions and higher reliability and ﬂexibility. Hence DGs ﬁnd</div><div class="t m5 x7 ha y50 ff1 fs6 fc0 sc0 ls0 ws0">many applications other than power generation, such as acting as</div><div class="t m5 x7 ha y51 ff1 fs6 fc0 sc0 ls0 ws0">backup sources and deferrals for upgrades in transmission and</div><div class="t m5 x7 ha y52 ff1 fs6 fc0 sc0 ls0 ws0">distribution systems [2].</div><div class="t m5 x8 ha y53 ff1 fs6 fc0 sc0 ls0 ws0">Yet, without optimal utilization of sources the cost of invest-</div><div class="t m5 x7 ha y54 ff1 fs6 fc0 sc0 ls0 ws0">ment for a microgrid shall not be justiﬁed. Optimization is to ﬁnd</div><div class="t m5 x9 ha y55 ff1 fs6 fc0 sc0 ls0 ws0">Contents lists available at ScienceDirect</div><div class="t m5 xa hb y56 ff8 fs6 fc0 sc0 ls3 ws0">journal homepage: w ww.elsevier .com/locate/rs er</div><div class="t m6 xb hc y57 ff1 fs7 fc0 sc0 ls0 ws0">Renewable and Sustainable Energy Reviews</div><div class="t m3 x1 h7 y58 ff1 fs3 fc1 sc0 ls0 ws0">http://dx.doi.org/10.1016/j.rser.2015.01.059</div><div class="t m3 x1 h7 y59 ff1 fs3 fc0 sc0 ls0 ws0">1364-0321/& 2015 Elsevier Ltd. All rights reserved.</div><div class="t m7 xc hd y5a ff3 fs8 fc0 sc0 ls0 ws0">n</div><div class="t m3 xd h7 y5b ff1 fs3 fc0 sc0 ls0 ws0">Corresponding author.</div><div class="t m3 x6 h7 y5c ff4 fs3 fc0 sc0 ls0 ws0">E-mail addresses: ahina.fathima2013@vit.ac.in,</div><div class="t m3 x1 h7 y5d ff1 fs3 fc1 sc0 ls0 ws0">hina.fathima49@gmail.com (A.H. Fathima), kpalanisamy@vit.ac.in (K. Palanisamy).</div><div class="t m3 xe h7 y5e ff1 fs3 fc1 sc0 ls0 ws0">Renewable and Sustainable Energy Reviews 45 (2015) 431–446</div><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></div></div> </body> </html>

<div id="pf2" class="pf w0 h0" data-page-no="2"><div class="pc pc2 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626419ba4f8811599e3883f5/bg2.jpg"><div class="t m5 xf ha y5f ff1 fs6 fc0 sc0 ls0 ws0">the best alternative of a set of given solutions which is most cost-</div><div class="t m5 xf ha y60 ff1 fs6 fc0 sc0 ls0 ws0">effective or has the highest achievable performance under the</div><div class="t m5 xf ha y61 ff1 fs6 fc0 sc0 ls0 ws0">given constraints. Hence optimization tools, techniques and appli-</div><div class="t m5 xf ha y62 ff1 fs6 fc0 sc0 ls0 ws0">cations are the most sought after topics for research in the recent</div><div class="t m5 xf ha y63 ff1 fs6 fc0 sc0 ls0 ws0">times. An attempt to summarise the importance of optimization</div><div class="t m5 xf ha y64 ff1 fs6 fc0 sc0 ls0 ws0">especially in the ﬁeld of microgrids with hybrid power sources is</div><div class="t m5 xf ha y65 ff1 fs6 fc0 sc0 ls0 ws0">presented. This paper also provides an overview of the various</div><div class="t m5 xf ha y66 ff1 fs6 fc0 sc0 ls0 ws0">hybrid microgrid systems currently being explored and the various</div><div class="t m5 xf ha y67 ff1 fs6 fc0 sc0 ls0 ws0">optimization methods and applications that are being employed.</div><div class="t m5 xf ha y68 ff1 fs6 fc0 sc0 ls0 ws0">While attempts have been made at summarizing optimization</div><div class="t m5 xf ha y69 ff1 fs6 fc0 sc0 ls0 ws0">tools [3] and methods [4] to hybrid systems, this paper is novel in</div><div class="t m5 xf ha y6a ff1 fs6 fc0 sc0 ls0 ws0">the sense it entails an account of various objectives in diverse</div><div class="t m5 xf ha y6b ff1 fs6 fc0 sc0 ls0 ws0">power system applications targeted for optimizing the HRES. The</div><div class="t m5 xf ha y6c ff1 fs6 fc0 sc0 ls0 ws0">paper is structured as follows. The evolution of microgrids and the</div><div class="t m5 xf ha y6d ff1 fs6 fc0 sc0 ls0 ws0">importance of optimization are briefed in Section 1.InSection 2,</div><div class="t m5 xf ha y6e ff1 fs6 fc0 sc0 ls0 ws0">Hybrid Renewable Energy Systems (HRES) are introduced and a</div><div class="t m5 xf ha y6f ff1 fs6 fc0 sc0 ls0 ws0">brief discussion followed by a review on the modelling of various</div><div class="t m5 xf ha y70 ff1 fs6 fc0 sc0 ls0 ws0">energy sources viz. – Solar, Wind, Diesel generators and Energy</div><div class="t m5 xf ha y71 ff1 fs6 fc0 sc0 ls0 ws0">Storage Systems (ESS) is presented. Section 3 gives an approximate</div><div class="t m5 xf ha y72 ff1 fs6 fc0 sc0 ls0 ws0">classiﬁcation of the application areas for optimization in micro-</div><div class="t m5 xf ha y73 ff1 fs6 fc0 sc0 ls0 ws0">grids. Objectives of optimization in the HRES are presented, taking</div><div class="t m5 xf ha y74 ff1 fs6 fc0 sc0 ls0 ws0">into account the trivial factors such as minimization of costs,</div><div class="t m5 xf ha y75 ff1 fs6 fc0 sc0 ls0 ws0">emissions and price arbitrages in Section 4. Section 5 lists the</div><div class="t m5 xf ha y76 ff1 fs6 fc0 sc0 ls0 ws0">various tools and techniques employed to perform optimization.</div><div class="t m5 xf ha y77 ff1 fs6 fc0 sc0 ls0 ws0">The reviews conclude with an overall discussion on potential areas</div><div class="t m5 xf ha y78 ff1 fs6 fc0 sc0 ls0 ws0">of development and future research.</div><div class="t m5 xf h9 y79 ff6 fs6 fc0 sc0 ls0 ws0">2. Hybrid renewable energy systems (HRES)</div><div class="t m5 x10 ha y7a ff1 fs6 fc0 sc0 ls0 ws0">Our planet houses enough power generating resources to cover</div><div class="t m5 xf ha y7b ff1 fs6 fc0 sc0 ls0 ws0">its ever growing demand for electricity. But the power generated</div><div class="t m5 xf ha y7c ff1 fs6 fc0 sc0 ls0 ws0">from some of these sources is intermittent or not of required</div><div class="t m5 xf ha y7d ff1 fs6 fc0 sc0 ls0 ws0">power quality owing to their stochastic nature. Hence a complete</div><div class="t m5 xf ha y7e ff1 fs6 fc0 sc0 ls0 ws0">transition from fuel based generation to renewable generation</div><div class="t m5 xf ha y7f ff1 fs6 fc0 sc0 ls0 ws0">society will need a non-single combination of these alternating</div><div class="t m5 xf ha y80 ff1 fs6 fc0 sc0 ls0 ws0">energies. Alternative energy sources like hydro, geothermal, bio-</div><div class="t m5 xf ha y81 ff1 fs6 fc0 sc0 ls0 ws0">mass, wind, solar, hydrogen, nuclear and fossil fuels need to be</div><div class="t m5 xf ha y82 ff1 fs6 fc0 sc0 ls0 ws0">made to work together in different combinations as a single unit to</div><div class="t m5 xf ha y83 ff1 fs6 fc0 sc0 ls0 ws0">meet a common demand area. The term HRES describes a system</div><div class="t m5 xf ha y84 ff1 fs6 fc0 sc0 ls0 ws0">having different DGs integrated to power the customer's demand.</div><div class="t m5 xf ha y85 ff1 fs6 fc0 sc0 ls0 ws0">HRES can be a combination of conventional sources like, diesel</div><div class="t m5 xf ha y86 ff1 fs6 fc0 sc0 ls0 ws0">generators and/or renewable sources like photovoltaics (PV) and</div><div class="t m5 xf ha y87 ff1 fs6 fc0 sc0 ls0 ws0">wind turbine (WT) exploited in various combinations with storage</div><div class="t m5 xf ha y88 ff1 fs6 fc0 sc0 ls0 ws0">systems as shown in Fig. 1.</div><div class="t m5 x10 ha y89 ff1 fs6 fc0 sc0 ls0 ws0">Remote areas providing hardships for laying of new transmis-</div><div class="t m5 xf ha y8a ff1 fs6 fc0 sc0 ls0 ws0">sion lines are ideal areas where HRES can be implemented to</div><div class="t m5 xf ha y8b ff1 fs6 fc0 sc0 ls0 ws0">ensure cost-effective and reliable delivery of power. Alternative</div><div class="t m5 xf ha y8c ff1 fs6 fc0 sc0 ls0 ws0">sources of energies are in wide use in developing the HRES</div><div class="t m5 xf ha y8d ff1 fs6 fc0 sc0 ls0 ws0">systems all around the world. They are also being installed to</div><div class="t m5 xf ha y8e ff1 fs6 fc0 sc0 ls0 ws0">generate power in large scales. Renewables like solar and wind</div><div class="t m5 xf ha y8f ff1 fs6 fc0 sc0 ls0 ws0">energies depend on climatic conditions. Hence they are very</div><div class="t m5 xf ha y90 ff1 fs6 fc0 sc0 ls0 ws0">difﬁcult to predict and impossible to control. However integrating</div><div class="t m5 xf ha y91 ff1 fs6 fc0 sc0 ls0 ws0">two or more resources that can compensate the drawbacks of one</div><div class="t m5 xf ha y92 ff1 fs6 fc0 sc0 ls0 ws0">another has found to overcome this problem. The idea is to use the</div><div class="t m5 xf ha y93 ff1 fs6 fc0 sc0 ls0 ws0">strengths and disadvantages of one source to counterbalance those</div><div class="t m5 xf ha y94 ff1 fs6 fc0 sc0 ls0 ws0">of the other. But there is now a new difﬁculty in analysing these</div><div class="t m5 xf ha y95 ff1 fs6 fc0 sc0 ls0 ws0">integrated systems due to the complexity of the combining</div><div class="t m5 xf ha y96 ff1 fs6 fc0 sc0 ls0 ws0">sources. Hence a lot of research is done in ﬁ nding the solutions</div><div class="t m5 xf ha y97 ff1 fs6 fc0 sc0 ls0 ws0">for optimum utilization of renewable sources to promote green</div><div class="t m5 xf ha y98 ff1 fs6 fc0 sc0 ls0 ws0">energy. Sizing, operation and control of the renewable sources in</div><div class="t m5 xf ha y99 ff1 fs6 fc0 sc0 ls0 ws0">an HRES are very essential for its techno-economical feasibility</div><div class="t m5 xf ha y9a ff1 fs6 fc0 sc0 ls0 ws0">and stability [5,6].</div><div class="t m5 x10 ha y9b ff1 fs6 fc0 sc0 ls0 ws0">Of the above mentioned energy technologies hydro, biomass</div><div class="t m5 xf ha y9c ff1 fs6 fc0 sc0 ls0 ws0">combustion and geothermal power form the ﬁ rst-generation</div><div class="t m5 xf ha y9d ff1 fs6 fc0 sc0 ls0 ws0">technologies which have been in use since the end of 19th century</div><div class="t m5 x11 ha y9e ff1 fs6 fc0 sc0 ls0 ws0">industrial revolution. Solar heating, wind power, bioenergy and</div><div class="t m5 x11 ha y9f ff1 fs6 fc0 sc0 ls0 ws0">photovoltaics belong to the second generation technologies which</div><div class="t m5 x11 ha ya0 ff1 fs6 fc0 sc0 ls0 ws0">emerged in late 90s through R&D. The oil crisis of 1970s created</div><div class="t m5 x11 ha ya1 ff1 fs6 fc0 sc0 ls0 ws0">the awareness of the depletion of fossil fuels prompting invest-</div><div class="t m5 x11 ha ya2 ff1 fs6 fc0 sc0 ls0 ws0">ment in alternate sources. But a growing concern for environ-</div><div class="t m5 x11 ha ya3 ff1 fs6 fc0 sc0 ls0 ws0">mental protection has sustained the development of the</div><div class="t m5 x11 ha ya4 ff1 fs6 fc0 sc0 ls0 ws0">renewable green energy. Further development has introduced</div><div class="t m5 x11 ha ya5 ff1 fs6 fc0 sc0 ls0 ws0">the third-generation technologies which include biomass, geother-</div><div class="t m5 x11 ha ya6 ff1 fs6 fc0 sc0 ls0 ws0">mal and ocean energies. Their development and implementation</div><div class="t m5 x11 ha ya7 ff1 fs6 fc0 sc0 ls0 ws0">are further aided by the advancement in the ﬁeld of nanotechnol-</div><div class="t m5 x11 ha ya8 ff1 fs6 fc0 sc0 ls0 ws0">ogy [7–9]. An estimate of the contribution of renewable sources to</div><div class="t m5 x11 ha ya9 ff1 fs6 fc0 sc0 ls0 ws0">power generation in India is given as in Table 1. (As on 28-2-2014</div><div class="t m5 x11 ha yaa ff1 fs6 fc0 sc0 ls0 ws0">Source:CEA). 12% of India's power is generated by renewables of</div><div class="t m5 x11 ha yab ff1 fs6 fc0 sc0 ls0 ws0">which about 70% of power comes from wind energy conversion</div><div class="t m5 x11 ha yac ff1 fs6 fc0 sc0 ls0 ws0">systems. An illustration is shown as Fig. 2.</div><div class="t m5 x12 ha yad ff1 fs6 fc0 sc0 ls0 ws0">This paper concentrates mostly on the systems integrating</div><div class="t m5 x11 ha yae ff1 fs6 fc0 sc0 ls0 ws0">solar, wind, diesel and energy storage systems. Solar and wind</div><div class="t m5 x11 ha yaf ff1 fs6 fc0 sc0 ls0 ws0">systems have been on the increase all over the globe to produce</div><div class="t m5 x11 ha yb0 ff1 fs6 fc0 sc0 ls0 ws0">electric power in the past decade. This is because they are</div><div class="t m5 x11 ha yb1 ff1 fs6 fc0 sc0 ls0 ws0">abundant in nature, clean and site-dependent. Also, owing to very</div><div class="t m5 x11 ha yb2 ff1 fs6 fc0 sc0 ls0 ws0">low maintenance costs, they are highly cost-effective. These</div><div class="t m5 x11 ha yb3 ff1 fs6 fc0 sc0 ls0 ws0">advantages have been attracting power researchers and investors</div><div class="t m5 x11 ha yb4 ff1 fs6 fc0 sc0 ls0 ws0">alike. A brief overview of the renewable energy sources and their</div><div class="t m5 x11 ha yb5 ff1 fs6 fc0 sc0 ls0 ws0">modelling is outlined below. Banosa et al. [10], gave a detailed</div><div class="t m5 x11 ha yb6 ff1 fs6 fc0 sc0 ls0 ws0">analysis on various research works carried in various alternative</div><div class="t m5 x11 ha yb7 ff1 fs6 fc0 sc0 ls0 ws0">energies. Many researchers have attempted to model the various</div><div class="t m5 x11 ha yb8 ff1 fs6 fc0 sc0 ls0 ws0">renewable systems. But a complete study of each is not in the</div><div class="t m5 x11 ha yb9 ff1 fs6 fc0 sc0 ls0 ws0">scope of this paper. However studies by Zhou et al. [11,12],</div><div class="t m5 x11 ha yba ff1 fs6 fc0 sc0 ls0 ws0">Deshmukh and Deshmukh [6] and Bajpai et al. [13] provide a</div><div class="t m5 x11 ha ybb ff1 fs6 fc0 sc0 ls0 ws0">review of research papers on the modelling of the renewable</div><div class="t m5 x11 ha ybc ff1 fs6 fc0 sc0 ls0 ws0">energy systems. The studies clearly point out that a combination of</div><div class="t m5 x11 ha ybd ff1 fs6 fc0 sc0 ls0 ws0">PV and Wind energy generation is growing increasingly popular</div><div class="t m5 x11 ha ybe ff1 fs6 fc0 sc0 ls0 ws0">owing to their complementary nature. Luna-Rubio et al. gave an</div><div class="t m5 x11 ha ybf ff1 fs6 fc0 sc0 ls0 ws0">overview on sizing methodologies considering hybrid energy</div><div class="t m5 x11 ha yc0 ff1 fs6 fc0 sc0 ls0 ws0">metrics like LPSP, SOC, LCE, etc. [14]. These system metrics are</div><div class="t m5 x11 ha yc1 ff1 fs6 fc0 sc0 ls0 ws0">explained further on in this paper. Many other papers which</div><div class="t m5 x11 ha yc2 ff1 fs6 fc0 sc0 ls0 ws0">explain modelling of the hybrid sources have also been included in</div><div class="t m5 x11 ha yc3 ff1 fs6 fc0 sc0 ls0 ws0">this section [5,6,15–20].</div><div class="t m5 x11 h9 yc4 ff4 fs6 fc0 sc0 ls0 ws0">2.1. Solar energy</div><div class="t m5 x12 ha yc5 ff1 fs6 fc0 sc0 ls0 ws0">Solar energy is the energy radiated by the sun, which is</div><div class="t m5 x11 ha yc6 ff1 fs6 fc0 sc0 ls0 ws0">harnessed by tapping light photons to generate electrons. Solar</div><div class="t m5 x11 ha yc7 ff1 fs6 fc0 sc0 ls0 ws0">energy is now generated on a large scale with many energy</div><div class="t m5 x11 ha yc8 ff1 fs6 fc0 sc0 ls0 ws0">investing companies promoting it. But it needs a lot of expertise</div><div class="t m5 x11 ha yc9 ff1 fs6 fc0 sc0 ls0 ws0">for implementation, site designing and development. Indian states</div><div class="t m5 x11 ha yca ff1 fs6 fc0 sc0 ls0 ws0">like Gujarat and Rajasthan are harnessing solar energy, thus</div><div class="t m5 x11 ha ycb ff1 fs6 fc0 sc0 ls0 ws0">completely utilizing their geographical position. Other states are</div><div class="t m5 x11 ha ycc ff1 fs6 fc0 sc0 ls0 ws0">also following suit to realise their solar potentials by reviewing</div><div class="t m5 x11 ha ycd ff1 fs6 fc0 sc0 ls0 ws0">their solar policies. The PV system consists of a photovoltaic array</div><div class="t m5 x11 ha yce ff1 fs6 fc0 sc0 ls0 ws0">which converts the light photons falling on it to electrons. This</div><div class="t m5 x11 ha ycf ff1 fs6 fc0 sc0 ls0 ws0">generates a DC current which can be boosted with DC–DC</div><div class="t m5 x11 ha yd0 ff1 fs6 fc0 sc0 ls0 ws0">converters and then inverted to deliver AC power to the loads.</div><div class="t m5 x11 ha yd1 ff1 fs6 fc0 sc0 ls0 ws0">Thus, power electronic devices form an important part in interfa-</div><div class="t m5 x11 ha yd2 ff1 fs6 fc0 sc0 ls0 ws0">cing the PV to the grid. Also, a speciﬁc Maximum Power Point</div><div class="t m5 x11 ha yd3 ff1 fs6 fc0 sc0 ls0 ws0">Tracking System (MPPT) is employed to enable the PV to extract</div><div class="t m5 x11 ha yd4 ff1 fs6 fc0 sc0 ls0 ws0">maximum energy from the sun by altering the slanting angle of its</div><div class="t m5 x11 ha yd5 ff1 fs6 fc0 sc0 ls0 ws0">rays all through the day. At last, the power is ﬁltered with a low-</div><div class="t m5 x11 ha yd6 ff1 fs6 fc0 sc0 ls0 ws0">pass ﬁlter to eliminate unwanted harmonics before it enters</div><div class="t m5 x11 ha yd7 ff1 fs6 fc0 sc0 ls0 ws0">the grid.</div><div class="t m5 x12 ha yd8 ff1 fs6 fc0 sc0 ls0 ws0">All PV cells are mostly made of semiconductor crystalline</div><div class="t m5 x11 ha yd9 ff1 fs6 fc0 sc0 ls0 ws0">materials. There are many types of PV cells as mono-crystalline,</div><div class="t m5 x11 ha yda ff1 fs6 fc0 sc0 ls0 ws0">poly-crystalline and thin-ﬁlm PV cells. New advancements in cell</div><div class="t m5 x11 ha ydb ff1 fs6 fc0 sc0 ls0 ws0">production technology have brought on the introduction of</div><div class="t m5 x11 ha ydc ff1 fs6 fc0 sc0 ls0 ws0">titanium-oxide coated PV cells which highly improves the output</div><div class="t m5 x11 ha ydd ff1 fs6 fc0 sc0 ls0 ws0">efﬁciency. The PV cells are grouped to form modules which can</div><div class="t m3 x13 h7 yde ff4 fs3 fc0 sc0 ls0 ws0">A.H. Fathima, K. Palanisamy / Renewable and Sustainable Energy Reviews 45 (2015) 431–446432</div><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></div></div>

<div id="pf3" class="pf w0 h0" data-page-no="3"><div class="pc pc3 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626419ba4f8811599e3883f5/bg3.jpg"><div class="t m5 x1 ha ydf ff1 fs6 fc0 sc0 ls0 ws0">then be electrically connected in series and/or in parallel forming</div><div class="t m5 x1 ha ye0 ff1 fs6 fc0 sc0 ls0 ws0">large units with scaled voltages and increased power outputs. An</div><div class="t m5 x1 ha ye1 ff1 fs6 fc0 sc0 ls0 ws0">MPPT system is most important for optimal absorption of solar</div><div class="t m5 x1 ha ye2 ff1 fs6 fc0 sc0 ls0 ws0">energy to maximize the efﬁciency of the conversion system.</div><div class="t m5 x7 ha ye3 ff1 fs6 fc0 sc0 ls0 ws0">Though the solar insolation may vary naturally through the day,</div><div class="t m5 x7 ha ye4 ff1 fs6 fc0 sc0 ls0 ws0">the MPPT system adjusts the PV array output to generate max-</div><div class="t m5 x7 ha ye5 ff1 fs6 fc0 sc0 ls0 ws0">imum real power at a constant voltage. Reactive power control is</div><div class="t m5 x7 ha ye6 ff1 fs6 fc0 sc0 ls0 ws0">done using an inverter controller operating in constant power</div><div class="t m5 x7 ha ye7 ff1 fs6 fc0 sc0 ls0 ws0">factor mode. A silicon PV module output depends on many</div><div class="t m5 x7 ha ye8 ff1 fs6 fc0 sc0 ls0 ws0">variable including the type of material, temperature and solar</div><div class="t m5 x7 ha ye9 ff1 fs6 fc0 sc0 ls0 ws0">radiance incident on the surface of the module. Its output can be</div><div class="t m5 x7 ha yea ff1 fs6 fc0 sc0 ls0 ws0">expressed as</div><div class="t m5 x7 h9 yeb ff4 fs6 fc0 sc0 ls0 ws0">P</div><div class="t m9 x14 he yec ff4 fs9 fc0 sc0 ls0 ws0">pv</div><div class="t m5 x15 h9 yed ffa fs6 fc0 sc0 ls0 ws0">¼ P</div><div class="t m9 x16 he yee ff4 fs9 fc0 sc0 ls0 ws0">STC</div><div class="t m5 x17 h9 yef ff4 fs6 fc0 sc0 ls0 ws0">G</div><div class="t m9 x18 he yf0 ff4 fs9 fc0 sc0 ls0 ws0">c</div><div class="t m5 x19 h9 yf1 ff4 fs6 fc0 sc0 ls0 ws0">G</div><div class="t m9 x1a he yf2 ff4 fs9 fc0 sc0 ls0 ws0">STC</div><div class="t m5 x1b ha yed ffa fs6 fc0 sc0 ls0 ws0">½1þkðT</div><div class="t m9 x1c he yec ff4 fs9 fc0 sc0 ls0 ws0">c</div><div class="t m5 x1d h9 yed ffa fs6 fc0 sc0 ls0 ws0">T</div><div class="t m9 x1e he yee ff4 fs9 fc0 sc0 ls0 ws0">STC</div><div class="t m5 x1f ha yed ffa fs6 fc0 sc0 ls0 ws0">Þ ð1Þ</div><div class="t m5 x7 ha yf3 ff1 fs6 fc0 sc0 ls0 ws0">where P</div><div class="t m9 x20 he yf4 ff4 fs9 fc0 sc0 ls0 ws0">pv</div><div class="t m5 x17 ha yf5 ff1 fs6 fc0 sc0 ls0 ws0">is the output power of PV module in watts, GSTC is solar</div><div class="t m5 x7 ha yf6 ff1 fs6 fc0 sc0 ls0 ws0">irradiance in W/m</div><div class="t ma x21 hf yf7 ff1 fsa fc0 sc0 ls0 ws0">2</div><div class="t m5 x22 ha yf8 ff1 fs6 fc0 sc0 ls0 ws0">, T is the temperature in 1C, GC is the irradiance</div><div class="t m5 x7 ha yf9 ff1 fs6 fc0 sc0 ls0 ws0">of operating point, k is the power temperature coefﬁcient, PSTC is</div><div class="t m5 x7 ha yfa ff1 fs6 fc0 sc0 ls0 ws0">the rated output generated by the module under standard test</div><div class="t m5 x7 ha yfb ff1 fs6 fc0 sc0 ls0 ws0">conditions in watts [5]. T</div><div class="t m9 x23 he yfc ff4 fs9 fc0 sc0 ls0 ws0">c</div><div class="t m5 x24 ha yfd ff1 fs6 fc0 sc0 ls0 ws0">can be calculated using the following</div><div class="t m5 x7 ha yfe ff1 fs6 fc0 sc0 ls0 ws0">expression:</div><div class="t m5 x7 h9 yff ff4 fs6 fc0 sc0 ls0 ws0">T</div><div class="t m9 x14 he y100 ff4 fs9 fc0 sc0 ls0 ws0">c</div><div class="t m5 x25 h9 y101 ffa fs6 fc0 sc0 ls0 ws0">¼ T</div><div class="t m9 x26 he y100 ff4 fs9 fc0 sc0 ls0 ws0">a</div><div class="t m5 x27 h10 y101 ffa fs6 fc0 sc0 ls0 ws0">þ</div><div class="t m5 x28 ha y102 ffa fs6 fc0 sc0 ls0 ws0">ðNOCT 20Þ</div><div class="t m5 x29 ha y103 ff1 fs6 fc0 sc0 ls0 ws0">0:8</div><div class="t m5 x1c ha y104 ff4 fs6 fc0 sc0 ls0 ws0">G ð2Þ</div><div class="t m5 x7 ha y105 ff1 fs6 fc0 sc0 ls0 ws0">where T</div><div class="t m9 x2a he y106 ff4 fs9 fc0 sc0 ls0 ws0">a</div><div class="t m5 x2b ha y107 ff1 fs6 fc0 sc0 ls0 ws0">is ambient temperature (in 1C), G is the global solar</div><div class="t m5 x7 ha y108 ff1 fs6 fc0 sc0 ls0 ws0">radiation incident on a horizontal plane (in kW/m</div><div class="t ma x2c hf y109 ff1 fsa fc0 sc0 ls0 ws0">2</div><div class="t m5 x2d ha y10a ff1 fs6 fc0 sc0 ls0 ws0">) and NOCT is</div><div class="t m5 x7 ha y10b ff1 fs6 fc0 sc0 ls0 ws0">the Normal Operating Cell Temperature, which is approximately</div><div class="t m5 x7 ha y10c ff1 fs6 fc0 sc0 ls8 ws0">48 1C. Considering that the PV modules are connected in series and</div><div class="t m5 x7 ha y10d ff1 fs6 fc0 sc0 ls0 ws0">in parallel as explained before to increase the output voltage and</div><div class="t m5 x7 ha y10e ff1 fs6 fc0 sc0 ls0 ws0">current. A matrix of N</div><div class="t ma x2e h11 y10f ff4 fsa fc0 sc0 ls0 ws0">S</div><div class="t m5 x2f h9 y110 ff4 fs6 fc0 sc0 ls9 ws0">XN</div><div class="t ma x30 h11 y10f ff4 fsa fc0 sc0 ls0 ws0">P</div><div class="t m5 x24 ha y110 ff1 fs6 fc0 sc0 ls0 ws0">PV modules is modelled here where N</div><div class="t ma x31 h11 y10f ff4 fsa fc0 sc0 ls0 ws0">S</div><div class="t m5 x7 ha y111 ff1 fs6 fc0 sc0 ls0 ws0">is the number of series connected modules and N</div><div class="t ma x2c h11 y112 ff4 fsa fc0 sc0 ls0 ws0">P</div><div class="t m5 x32 ha y111 ff1 fs6 fc0 sc0 ls0 ws0">indicates the</div><div class="t m5 x7 ha y113 ff1 fs6 fc0 sc0 ls0 ws0">no.of modules connected in parallel. The output voltage and power</div><div class="t m5 x7 ha y114 ff1 fs6 fc0 sc0 ls0 ws0">of the PV system is given as</div><div class="t m5 x7 h9 y115 ff4 fs6 fc0 sc0 ls0 ws0">V</div><div class="t m9 x33 he y116 ff4 fs9 fc0 sc0 lsa ws0">PVA</div><div class="t m5 x34 h9 y117 ffa fs6 fc0 sc0 ls0 ws0">¼ N</div><div class="t m9 x2a he y118 ff4 fs9 fc0 sc0 lsa ws0">PVS</div><div class="t m5 x35 h9 y117 ff4 fs6 fc0 sc0 ls0 ws0">V</div><div class="t m9 x36 he y119 ff4 fs9 fc0 sc0 lsb ws0">PV</div><div class="t m5 x37 ha y117 ffa fs6 fc0 sc0 ls0 ws0">ð3Þ</div><div class="t m5 x7 h9 y11a ff4 fs6 fc0 sc0 ls0 ws0">P</div><div class="t m9 x14 he y11b ff4 fs9 fc0 sc0 lsb ws0">PV</div><div class="t m5 x38 h9 y11c ffa fs6 fc0 sc0 ls0 ws0">¼ N</div><div class="t m9 x39 he y11b ff4 fs9 fc0 sc0 ls0 ws0">P</div><div class="t m5 x3a h9 y11c ff4 fs6 fc0 sc0 ls0 ws0">N</div><div class="t m9 x3b he y11d ff4 fs9 fc0 sc0 ls0 ws0">S</div><div class="t m5 x1a h9 y11c ff4 fs6 fc0 sc0 ls0 ws0">P</div><div class="t m9 x3c he y11e ff4 fs9 fc0 sc0 ls0 ws0">module</div><div class="t m5 x3d h12 y11c ffd fs6 fc0 sc0 ls0 ws0">η</div><div class="t m9 x3e he y11f ff4 fs9 fc0 sc0 lsa ws0">MPPT</div><div class="t m5 x3f h12 y11c ffd fs6 fc0 sc0 ls0 ws0">η</div><div class="t m9 x40 he y11f ff4 fs9 fc0 sc0 ls0 ws0">oth</div><div class="t m5 x37 ha y11c ffa fs6 fc0 sc0 ls0 ws0">ð4Þ</div><div class="t m3 x41 h7 y120 ff6 fs3 fc0 sc0 ls0 ws0">Fig. 1. Hybrid renewable energy sytems.</div><div class="t m3 x1 h5 y121 ff6 fs3 fc0 sc0 ls0 ws0">Table 1</div><div class="t m3 x1 h7 y122 ff1 fs3 fc0 sc0 ls0 ws0">India's energy sources and their contribution to the total power (as on 28-2-2014).</div><div class="t m3 x42 h7 y123 ff1 fs3 fc0 sc0 ls0 ws0">Type of source Generation capacity in MW Percentage</div><div class="t m3 x42 h7 y124 ff1 fs3 fc0 sc0 ls0 ws0">Coal 140723.39 59.19</div><div class="t m3 x42 h7 y125 ff1 fs3 fc0 sc0 ls0 ws0">Gas 21381.85 8.99</div><div class="t m3 x42 h7 y126 ff1 fs3 fc0 sc0 ls0 ws0">Oil 1199.75 0.50</div><div class="t m3 x42 h7 y127 ff1 fs3 fc0 sc0 ls0 ws0">Hydro (Renewable) 40195.4 16.91</div><div class="t m3 x42 h7 y128 ff1 fs3 fc0 sc0 ls0 ws0">Nuclear 4780 2.01</div><div class="t m3 x42 h7 y129 ff1 fs3 fc0 sc0 ls0 ws0">RES 29462.55 12.39</div><div class="t m3 x42 h7 y12a ff1 fs3 fc0 sc0 ls0 ws0">Total 237742.94 100</div><div class="t m3 x43 h7 y12b ff6 fs3 fc0 sc0 ls0 ws0">Fig. 2. India's energy generating sources and their contribution.</div><div class="t m3 x44 h7 y12c ff4 fs3 fc0 sc0 ls0 ws0">A.H. Fathima, K. Palanisamy / Renewable and Sustainable Energy Reviews 45 (2015) 431–446 433</div><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></div></div>

<div id="pf4" class="pf w0 h0" data-page-no="4"><div class="pc pc4 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/626419ba4f8811599e3883f5/bg4.jpg"><div class="t m5 xf ha y5f ff1 fs6 fc0 sc0 ls0 ws0">where η</div><div class="t m9 x45 he y12d ff4 fs9 fc0 sc0 lsa ws0">MPPT</div><div class="t m5 x46 ha y5f ff1 fs6 fc0 sc0 ls0 ws0">is the efﬁciency of the MPPT system and η</div><div class="t m9 x47 he y12d ff4 fs9 fc0 sc0 ls0 ws0">oth</div><div class="t m5 x48 ha y5f ff1 fs6 fc0 sc0 ls0 ws0">is the</div><div class="t m5 xf ha y60 ff1 fs6 fc0 sc0 ls0 ws0">factor which represents cable resistance and other losses [15]. The</div><div class="t m5 xf ha y61 ff1 fs6 fc0 sc0 ls0 ws0">local observatories usually provide data on solar irradiance as</div><div class="t m5 xf ha y62 ff1 fs6 fc0 sc0 ls0 ws0">incident on a horizontal plane. Hence Hongxing et al. [16]</div><div class="t m5 xf ha y63 ff1 fs6 fc0 sc0 ls0 ws0">employed the Perez model which helps to ﬁnd the solar irradiance</div><div class="t m5 xf ha y64 ff1 fs6 fc0 sc0 ls0 ws0">data for slanting planes with the aim to exploit maximum η at</div><div class="t m5 xf ha y65 ff1 fs6 fc0 sc0 ls0 ws0">any time.</div><div class="t m5 xf h9 y12e ff4 fs6 fc0 sc0 ls0 ws0">2.2. Wind energy</div><div class="t m5 x10 ha y12f ff1 fs6 fc0 sc0 ls0 ws0">Wind is the most promising source of alternate energy. Though</div><div class="t m5 xf ha y130 ff1 fs6 fc0 sc0 ls0 ws0">USA and China are the fastest growing wind power countries in</div><div class="t m5 xf ha y131 ff1 fs6 fc0 sc0 ls0 ws0">the world, European countries are the actual leaders. Germany and</div><div class="t m5 xf ha y132 ff1 fs6 fc0 sc0 ls0 ws0">Spain have the highest installed wind generation capacity of the</div><div class="t m5 xf ha y133 ff1 fs6 fc0 sc0 ls0 ws0">world. India has started developing wind power from the early 90s</div><div class="t m5 xf ha y134 ff1 fs6 fc0 sc0 ls0 ws0">and it now boasts of housing the ﬁfth largest wind power</div><div class="t m5 xf ha y135 ff1 fs6 fc0 sc0 ls0 ws0">installation in the world. Even though our country is relatively a</div><div class="t m5 xf ha y136 ff1 fs6 fc0 sc0 ls0 ws0">newcomer when compared to Denmark and USA, the Indian wind</div><div class="t m5 xf ha y137 ff1 fs6 fc0 sc0 ls0 ws0">industry has increased signiﬁcantly in the past decade. India</div><div class="t m5 xf ha y138 ff1 fs6 fc0 sc0 ls0 ws0">ranked ﬁrst in the growth rate of wind power generation in the</div><div class="t m5 xf ha y139 ff1 fs6 fc0 sc0 ls0 ws0">world during the year 2009–2010. The state of Tamil Nadu</div><div class="t m5 xf ha y13a ff1 fs6 fc0 sc0 ls0 ws0">generating more than 7000 MW is the leading state contributing</div><div class="t m5 xf ha y13b ff1 fs6 fc0 sc0 ls0 ws0">to about 40% of India's wind power. It is rightfully deemed as a</div><div class="t m5 xf ha y13c ff1 fs6 fc0 sc0 ls0 ws0">wind power hub of South Asia. The power (energy/second)</div><div class="t m5 xf ha y13d ff1 fs6 fc0 sc0 ls0 ws0">available in the wind will be given by the formula</div><div class="t m5 xf ha y13e ff1 fs6 fc0 sc0 ls0 ws0">Power ¼ 0:5AρV</div><div class="t m9 x49 h13 y13f ff1 fs9 fc0 sc0 ls0 ws0">3</div><div class="t m5 x4a h9 y140 ff4 fs6 fc0 sc0 ls0 ws0">C</div><div class="t m9 x4b he y141 ff4 fs9 fc0 sc0 ls0 ws0">p</div><div class="t m5 x4c ha y140 ffa fs6 fc0 sc0 ls0 ws0">ð5Þ</div><div class="t m5 xf ha y142 ff1 fs6 fc0 sc0 ls0 ws0">where A is the rotor swept area in m</div><div class="t ma x4d hf y143 ff1 fsa fc0 sc0 ls0 ws0">2</div><div class="t m5 x4e ha y144 ff1 fs6 fc0 sc0 ls0 ws0">, ρ is the air density in kg/m</div><div class="t ma x4f hf y143 ff1 fsa fc0 sc0 ls0 ws0">3</div><div class="t m5 x50 ha y144 ff1 fs6 fc0 sc0 ls0 ws0">,</div><div class="t m5 xf ha y145 ff4 fs6 fc0 sc0 ls0 ws0">V is the average wind velocity in (m/s) and C</div><div class="t ma x51 h11 y146 ff4 fsa fc0 sc0 ls0 ws0">p</div><div class="t m5 x52 ha y147 ff1 fs6 fc0 sc0 ls0 ws0">is the power</div><div class="t m5 xf ha y148 ff1 fs6 fc0 sc0 ls0 ws0">coefﬁcient, which is a function of tip-speed ratio and rotor</div><div class="t m5 xf ha y149 ff1 fs6 fc0 sc0 ls0 ws0">mechanical speed. It can be noted that the power generated is</div><div class="t m5 xf ha y14a ff1 fs6 fc0 sc0 ls0 ws0">proportional to the cube of the wind velocity, hence a small</div><div class="t m5 xf ha y14b ff1 fs6 fc0 sc0 ls0 ws0">difference in wind speed can effectively create a large difference</div><div class="t m5 xf ha y14c ff1 fs6 fc0 sc0 ls0 ws0">in the available energy and the cost of generation. Wind turbines</div><div class="t m5 xf ha y14d ff1 fs6 fc0 sc0 ls0 ws0">have a lifespan of about 20 years. They are most effectively used in</div><div class="t m5 xf ha y14e ff1 fs6 fc0 sc0 ls0 ws0">groups known as ‘wind farms’ or ‘wind power plants’ with</div><div class="t m5 xf ha y14f ff1 fs6 fc0 sc0 ls0 ws0">capacities varying from a few megawatts to few hundred mega-</div><div class="t m5 xf ha y150 ff1 fs6 fc0 sc0 ls0 ws0">watts in capacity. Though wind farms are spread over a large</div><div class="t m5 xf ha y151 ff1 fs6 fc0 sc0 ls0 ws0">geographical area, their actual “footprint” covers only a very small</div><div class="t m5 xf ha y152 ff1 fs6 fc0 sc0 ls0 ws0">portion of the land. Thus, a vast area of land is available to farmers</div><div class="t m5 xf ha y153 ff1 fs6 fc0 sc0 ls0 ws0">to earn additional revenue, thereby revitalizing the economy of</div><div class="t m5 xf ha y154 ff1 fs6 fc0 sc0 ls0 ws0">the rural communities.</div><div class="t m5 x10 ha y155 ff1 fs6 fc0 sc0 ls0 ws0">The development of wind power has encouraged the develop-</div><div class="t m5 xf ha y156 ff1 fs6 fc0 sc0 ls0 ws0">ment of turbines and auxiliary equipment. Due to extensive</div><div class="t m5 xf ha y157 ff1 fs6 fc0 sc0 ls0 ws0">research in this ﬁeld in the recent past there has been an increase</div><div class="t m5 xf ha y158 ff1 fs6 fc0 sc0 ls0 ws0">in size of turbine and reduction in the prize of installation.</div><div class="t m5 xf ha y159 ff1 fs6 fc0 sc0 ls0 ws0">Limitations found are low speed of the wind thereby making</div><div class="t m5 xf ha y15a ff1 fs6 fc0 sc0 ls0 ws0">siting and prediction procedures to be of vital importance. Wind</div><div class="t m5 xf ha y15b ff1 fs6 fc0 sc0 ls0 ws0">energy potential depends on operation scheme, wind speed</div><div class="t m5 xf ha y15c ff1 fs6 fc0 sc0 ls0 ws0">estimation, site selection for farms, etc. However primary interest</div><div class="t m5 xf ha y15d ff1 fs6 fc0 sc0 ls0 ws0">for researchers also lies in optimal design of wind farms including</div><div class="t m5 xf ha y15e ff1 fs6 fc0 sc0 ls0 ws0">design of wind turbine and layout of farms [10]. The difﬁculty in</div><div class="t m5 xf ha y15f ff1 fs6 fc0 sc0 ls0 ws0">setting up more wind farms is the unavailability of wind forecast</div><div class="t m5 xf ha y160 ff1 fs6 fc0 sc0 ls0 ws0">data as compared to solar forecast data. This is because solar</div><div class="t m5 xf ha y161 ff1 fs6 fc0 sc0 ls0 ws0">energy is comparatively more predictable than wind energy.</div><div class="t m5 xf ha y162 ff1 fs6 fc0 sc0 ls0 ws0">Hence siting of wind parks is a highly important aspect which</div><div class="t m5 xf ha y163 ff1 fs6 fc0 sc0 ls0 ws0">involves huge efforts to conduct studies and analysis of wind in</div><div class="t m5 xf ha y164 ff1 fs6 fc0 sc0 ls0 ws0">that area. Wind Energy Conversion Systems (WECS) convert wind</div><div class="t m5 xf ha y165 ff1 fs6 fc0 sc0 ls0 ws0">energy to electrical energy in two steps – First a turbine converts</div><div class="t m5 xf ha y166 ff1 fs6 fc0 sc0 ls0 ws0">the wind power to mechanical torque which then rotates a</div><div class="t m5 xf ha y167 ff1 fs6 fc0 sc0 ls0 ws0">generator to produce an electric current. WECS maybe classiﬁed</div><div class="t m5 xf ha y168 ff1 fs6 fc0 sc0 ls0 ws0">as ﬁxed speed and variable speed systems. Double-Fed Induction</div><div class="t m5 xf ha y169 ff1 fs6 fc0 sc0 ls0 ws0">Generators (DFIG) and Permanent Magnet Synchronous Genera-</div><div class="t m5 xf ha y16a ff1 fs6 fc0 sc0 ls0 ws0">tors (PMSG) are the most outstanding technologies in use for the</div><div class="t m5 xf ha y16b ff1 fs6 fc0 sc0 ls0 ws0">variable-speed WT's. The WT maybe connected to the generators</div><div class="t m5 xf ha y16c ff1 fs6 fc0 sc0 ls0 ws0">through a gear-box and capacitor banks are provided as DC links.</div><div class="t m5 x11 ha y16d ff1 fs6 fc0 sc0 ls0 ws0">Further, converters are used to economically invert the DC power</div><div class="t m5 x11 ha y16e ff1 fs6 fc0 sc0 ls0 ws0">generated and for compensation and interconnection purposes.</div><div class="t m5 x11 ha y16f ff1 fs6 fc0 sc0 ls0 ws0">Power control is implemented at various stages of the WECS.</div><div class="t m5 x11 ha y170 ff1 fs6 fc0 sc0 ls0 ws0">Mechanically the torque generated by the WT can be controlled by</div><div class="t m5 x11 ha y171 ff1 fs6 fc0 sc0 ls0 ws0">pitch angle control of the turbine blades. The electric power</div><div class="t m5 x11 ha y172 ff1 fs6 fc0 sc0 ls0 ws0">generated by the DFIGs can be controlled using bidirectional</div><div class="t m5 x11 ha y173 ff1 fs6 fc0 sc0 ls0 ws0">power converters interfaced between the rotor windings and the</div><div class="t m5 x11 ha y174 ff1 fs6 fc0 sc0 ls0 ws0">grid. They are usually constructed with two IGBT bridges linked</div><div class="t m5 x11 ha y175 ff1 fs6 fc0 sc0 ls0 ws0">back-to-back with a capacitor provided in between to serve as the</div><div class="t m5 x11 ha y176 ff1 fs6 fc0 sc0 ls0 ws0">DC link.</div><div class="t m5 x12 ha y177 ff1 fs6 fc0 sc0 ls0 ws0">The expression for output power of a wind turbine can be</div><div class="t m5 x11 ha y178 ff1 fs6 fc0 sc0 ls0 ws0">related to wind speed with the following function [5]:</div><div class="t m5 x11 h9 y179 ff4 fs6 fc0 sc0 ls0 ws0">P</div><div class="t m9 x53 he y17a ff4 fs9 fc0 sc0 lsd ws0">wt</div><div class="t m5 x12 h9 y17b ffa fs6 fc0 sc0 ls0 ws0">ðvÞ¼</div><div class="t m5 x54 ha y17c ff1 fs6 fc0 sc0 ls0 ws0">0; vr vci or vZ vco</div><div class="t m9 x20 he y17d ff4 fs9 fc0 sc0 ls0 ws0">P</div><div class="t mb x28 h14 y17e ff4 fsb fc0 sc0 lsf ws0">ratedwt</div><div class="t m9 x1b he y17d ffa fs9 fc0 sc0 ls0 ws0">ðv  v</div><div class="t mb x55 h14 y17f ff4 fsb fc0 sc0 ls11 ws0">ci</div><div class="t m9 x3e h15 y17d ffa fs9 fc0 sc0 ls0 ws0">Þ</div><div class="t m9 x17 he y180 ffa fs9 fc0 sc0 ls0 ws0">ðvr  vciÞ</div><div class="t m5 x56 h9 y181 ffc fs6 fc0 sc0 ls0 ws0">; vcir vr vr</div><div class="t m5 x19 h9 y182 ff4 fs6 fc0 sc0 ls0 ws0">P</div><div class="t m9 x2b he y183 ff4 fs9 fc0 sc0 ls12 ws0">ratedwt</div><div class="t m5 x55 h9 y184 ffc fs6 fc0 sc0 ls0 ws0">; vr r vr vco</div><div class="t m5 x57 h16 y185 fff fs6 fc0 sc0 ls0 ws0">8</div><div class="t m5 x57 h16 y186 fff fs6 fc0 sc0 ls0 ws0">></div><div class="t m5 x57 h16 y187 fff fs6 fc0 sc0 ls0 ws0"><</div><div class="t m5 x57 h16 y188 fff fs6 fc0 sc0 ls0 ws0">></div><div class="t m5 x57 h16 y189 fff fs6 fc0 sc0 ls0 ws0">:</div><div class="t m5 x58 ha y18a ffa fs6 fc0 sc0 ls0 ws0">ð6Þ</div><div class="t m5 x11 ha y18b ff1 fs6 fc0 sc0 ls0 ws0">where v</div><div class="t ma x26 h11 y18c ff4 fsa fc0 sc0 ls0 ws0">ci</div><div class="t m5 x27 ha y18d ff1 fs6 fc0 sc0 ls0 ws0">, v</div><div class="t ma x3b h11 y18c ff4 fsa fc0 sc0 ls0 ws0">co</div><div class="t m5 x59 ha y18d ff1 fs6 fc0 sc0 ls0 ws0">and v</div><div class="t ma x5a h11 y18c ff4 fsa fc0 sc0 ls0 ws0">r</div><div class="t m5 x5b ha y18d ff1 fs6 fc0 sc0 ls0 ws0">are cut-in, cut-off and rated wind speeds</div><div class="t m5 x11 ha y18e ff1 fs6 fc0 sc0 ls0 ws0">respectively. P</div><div class="t ma x5c h11 y18f ff4 fsa fc0 sc0 ls0 ws0">rated-wt</div><div class="t m5 x56 ha y190 ff1 fs6 fc0 sc0 ls0 ws0">is the rated output power of the WT. Final</div><div class="t m5 x11 ha y191 ff1 fs6 fc0 sc0 ls0 ws0">output P</div><div class="t m9 x5d he y192 ff4 fs9 fc0 sc0 ls0 ws0">out</div><div class="t m5 x5e h9 y193 ffe fs6 fc0 sc0 ls0 ws0">r P</div><div class="t m9 x54 he y192 ff4 fs9 fc0 sc0 ls0 ws0">wt</div><div class="t m5 x5f ha y193 ffa fs6 fc0 sc0 ls0 ws0">ðvÞ due to losses. The output power of wind</div><div class="t m5 x11 ha y194 ff1 fs6 fc0 sc0 ls0 ws0">turbine can always be adjusted to match the load demand. Qi</div><div class="t m5 x11 ha y195 ff1 fs6 fc0 sc0 ls0 ws0">et al. [18] categorized the operation of WT unit into three states</div><div class="t m5 x11 ha y196 ff1 fs6 fc0 sc0 ls0 ws0">depending on the load demand and operating wind speeds. When</div><div class="t m5 x11 ha y197 ff1 fs6 fc0 sc0 ls0 ws0">load exceeds generated power, the WT is operated in Maximum</div><div class="t m5 x11 ha y198 ff1 fs6 fc0 sc0 ls0 ws0">Power Point Tracking (MPPT) state. The system is operated under</div><div class="t m5 x11 ha y199 ff1 fs6 fc0 sc0 ls0 ws0">rated wind speed to capture efﬁcient wind energy. Whereas at</div><div class="t m5 x11 ha y19a ff1 fs6 fc0 sc0 ls0 ws0">times when load is lesser than the power generated, WT is said to</div><div class="t m5 x11 ha y19b ff1 fs6 fc0 sc0 ls0 ws0">be in load power tracking control state. Here the generator speed</div><div class="t m5 x11 ha y19c ff1 fs6 fc0 sc0 ls0 ws0">is controlled so that the system now generates only as much</div><div class="t m5 x11 ha y19d ff1 fs6 fc0 sc0 ls0 ws0">energy, as to satisfy the load demand and charge the battery</div><div class="t m5 x11 ha y19e ff1 fs6 fc0 sc0 ls0 ws0">storage if necessary. At high wind speeds, exceeding v</div><div class="t ma x60 h11 y19f ff4 fsa fc0 sc0 ls0 ws0">r</div><div class="t m5 x61 ha y1a0 ff1 fs6 fc0 sc0 ls0 ws0">, the WT</div><div class="t m5 x11 ha y1a1 ff1 fs6 fc0 sc0 ls0 ws0">operates in over speed protection state. So that, the speed of</div><div class="t m5 x11 ha y1a2 ff1 fs6 fc0 sc0 ls0 ws0">rotation is controlled and, therefore, prevents any harm to the</div><div class="t m5 x11 ha y1a3 ff1 fs6 fc0 sc0 ls0 ws0">electrical unit of the system. There are always limitations which</div><div class="t m5 x11 ha y1a4 ff1 fs6 fc0 sc0 ls0 ws0">one must consider in order to operate the WT safely and within</div><div class="t m5 x11 ha y1a5 ff1 fs6 fc0 sc0 ls0 ws0">reasonable speed limits. Dump loads are very handy in preventing</div><div class="t m5 x11 ha y1a6 ff1 fs6 fc0 sc0 ls0 ws0">over speeding of the WT.</div><div class="t m5 x12 ha y1a7 ff1 fs6 fc0 sc0 ls0 ws0">Modelling for wind generation is briefed in some of the papers</div><div class="t m5 x11 ha y1a8 ff1 fs6 fc0 sc0 ls0 ws0">studied [5,6,15,17,19,20]. Sarrias et al. gave a detailed modelling of</div><div class="t m5 x11 ha y1a9 ff1 fs6 fc0 sc0 ls0 ws0">the DFIG and its power converter and thereby analysed the</div><div class="t m5 x11 ha y1aa ff1 fs6 fc0 sc0 ls0 ws0">controller performance for optimal energy management [21]. Zhao</div><div class="t m5 x11 ha y1ab ff1 fs6 fc0 sc0 ls0 ws0">et al. [22], modelled a DFIG wind turbine which took into</div><div class="t m5 x11 ha y1ac ff1 fs6 fc0 sc0 ls0 ws0">consideration distribution network reconﬁguration with effective</div><div class="t m5 x11 ha y1ad ff1 fs6 fc0 sc0 ls0 ws0">reactive power control. Particle Swarm Optimization (PSO) algo-</div><div class="t m5 x11 ha y1ae ff1 fs6 fc0 sc0 ls0 ws0">rithm was used to minimize the system real power losses and</div><div class="t m5 x11 ha y1af ff1 fs6 fc0 sc0 ls0 ws0">voltage deviations, subject to operating constraints.</div><div class="t m5 x11 h9 y1b0 ff4 fs6 fc0 sc0 ls0 ws0">2.3. Diesel generators</div><div class="t m5 x12 ha y1b1 ff1 fs6 fc0 sc0 ls0 ws0">To promote green energy, diesel generators are now mostly</div><div class="t m5 x11 ha y1b2 ff1 fs6 fc0 sc0 ls0 ws0">used only as backup resources in HRES. In the case of the renew-</div><div class="t m5 x11 ha y1b3 ff1 fs6 fc0 sc0 ls0 ws0">able sources and battery systems failing to supply the load, diesel</div><div class="t m5 x11 ha y1b4 ff1 fs6 fc0 sc0 ls0 ws0">generators are brought into action. There are many deciding</div><div class="t m5 x11 ha y1b5 ff1 fs6 fc0 sc0 ls0 ws0">factors for the choice of diesel generators including types of load,</div><div class="t m5 x11 ha y1b6 ff1 fs6 fc0 sc0 ls0 ws0">fuel costs, transportation costs, etc. [23]. Deshmukh and Desh-</div><div class="t m5 x11 ha y1b7 ff1 fs6 fc0 sc0 ls0 ws0">mukh considered a sizing problem of engine generator under two</div><div class="t m5 x11 ha y1b8 ff1 fs6 fc0 sc0 ls0 ws0">conditions – one when the diesel generator is tied to the load</div><div class="t m5 x11 ha y1b9 ff1 fs6 fc0 sc0 ls0 ws0">directly and another when it is used as a battery charger [6].</div><div class="t m5 x11 ha y1ba ff1 fs6 fc0 sc0 ls0 ws0">Overall efﬁciency of the diesel generator can be expressed as</div><div class="t m5 x11 h12 y1bb ffd fs6 fc0 sc0 ls0 ws0">η</div><div class="t m9 x62 he y1bc ff4 fs9 fc0 sc0 ls0 ws0">overall</div><div class="t m5 x38 h10 y1bd ffa fs6 fc0 sc0 ls0 ws0">¼ η</div><div class="t m9 x5d he y1bc ff4 fs9 fc0 sc0 ls0 ws0">brake thermal</div><div class="t m5 x63 h10 y1bd ffa fs6 fc0 sc0 ls0 ws0"> η</div><div class="t m9 x5b he y1bc ff4 fs9 fc0 sc0 ls0 ws0">generator</div><div class="t m5 x58 ha y1bd ffa fs6 fc0 sc0 ls0 ws0">ð7Þ</div><div class="t m5 x11 ha y1be ff1 fs6 fc0 sc0 ls0 ws0">where η</div><div class="t m9 x57 he y1bf ff4 fs9 fc0 sc0 ls0 ws0">brake thermal</div><div class="t m5 x3d ha y1c0 ff1 fs6 fc0 sc0 ls0 ws0">is brake thermal efﬁciency of diesel engine.</div><div class="t m5 x11 ha y1c1 ff1 fs6 fc0 sc0 ls0 ws0">Operation of the generator at 70–90% of full load is found to be</div><div class="t m5 x11 ha y1c2 ff1 fs6 fc0 sc0 ls0 ws0">economical. Diesel generators are, thus helpful in boosting power</div><div class="t m5 x11 ha y1c3 ff1 fs6 fc0 sc0 ls0 ws0">during peak demand hours and later for energizing the energy</div><div class="t m5 x11 ha y1c4 ff1 fs6 fc0 sc0 ls0 ws0">storage units as and when required. Power limits for diesel</div><div class="t m3 x13 h7 yde ff4 fs3 fc0 sc0 ls0 ws0">A.H. Fathima, K. Palanisamy / Renewable and Sustainable Energy Reviews 45 (2015) 431–446434</div><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a><a class="l" rel='nofollow' onclick='return false;'><div class="d m8"></div></a></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></div></div>