A Nonlinear Controller for Photovoltaic Water Pumping System

Transcription

1 Intenational Jounal of Engineeing Tens an Technology (IJETT) - Volume4Issue5- ay 013 A Nonlinea Contolle fo Photovoltaic Wate Pumping System Hai Kishnan P 1, Ashokkuma K, Bhaathkuma S 3 1 Assistant pofesso, Anna univesity Regional cente, Coimbatoe II Yea E Contol an instumentation, EEE Depatment, Anna Univesity Regional cente, Coimbatoe 3 II Yea E Powe Systems Engineeing, EEE Depatment, Anna Univesity Regional cente, Coimbatoe Abstact : The aim of this wok is to suppy an enegy fo photovoltaic cell an that enegy will go to the invete an then went to inuction moto to be opeating cetain spee then wate pumb pocess achieve. ain taget is to esign an simulation of pulse with moulation (PW) base sliing moe (S) contolle fo DC/DC boost convete opeating in continuous conuction moe.this eseach aim is to be applie an application of the sliing moe contol aesse in this pape It is shown that this contol appoach can give goo esults in tems of obustness towa loa an input voltage vaiations moto. A contolle esign base on sliing moe contol has been teste on this pocess moel. The sliing moe algoithm povies obust contol of the pocess an pefoms fa supeio to conventional PI contol. A nonlinea contol of an inuction moto (I) supplie with a photovoltaic geneato to assue the level contol of two couple tanks is esigne. The global system is ecompose into two sepaate moels thus, couple ae assue by iscontinuous comman. The use of the nonlinea sliing moe metho povies a vey goo pefomance fo moto opeation an obustness of the contol law espite the extenal/intenal petubation. Simulation esults ae given to highlight the pefomance of the popose contol technique une loa istubances an paamete uncetainties. Key wos: Sliing moe contol, photovoltaic enegy, DC-DC boost convete, Pulse with moulation, tanks, Inuction moto, wate pumping system. I INTRODUCTION The eman of Enegy inceases these last yea consieably on the one han, as the conventional enegy souces ae winling an have a negative impact on the envionment (geenhouse gases effect) in the othe han, consieable attention is being pai to othe altenative souces as known the enewable enegies. The popose system will make use of a clean an enewable souce of enegy. Fom economic point of view, the photovoltaic enegy souce is suitable fo enegizing systems establishe in emote aea. Since the opeating point of the photovoltaic systems vaies accoingly with the sola iaiation, the tempeatue an the loa, they may be esigne to opeate at the equie voltage an cuent easily. In ou application to ovecome the poblem of the vaiation of the opeating point, one bings back oneself to exploit the maximum powe povie by the photovoltaic system by using a technique of maximum powe point tacke (PPT) an we have to size the photovoltaic system supplie the inuction moto. vaiable spee contol of motos is one of the key technologies that suppot moen inusty. Both DC an AC machines have seve inustial nees fo nealy a centuy. Howeve, the electical stuctues of inuction motos ae highly nonlinea an involve multivaiable inputs an outputs, the electic oto vaiables ae not measuable, an the physical moel paametes ae most often impecisely known. Theefoe, aitional effot is equie to ecouple an lineaize the contol of these machines. Hencefoth, the contol of the inuction motos has attacte much attention in the last two ecaes. II DESCRIPTION The sliing moe contolle is esigne fo a class of nonlinea ynamic systems to tackle the poblems with moel uncetainties, paamete fluctuations an extenal istubances. By this esign, the bouns of the uncetainties ae not equie to be known in avance. The vaiable stuctue contol (VSC) possesses this obustness using the sliing moe contol that can offe many goo popeties such as goo pefomance against unmoelle ynamics, insensitivity to paamete vaiation,extenal istubance ejection an fast ynamic (Utkin, 1977). These avantages of sliing moe contol can be employe in the position an spee contol of an altenative cuent system. In this pape, we begin with the I oiente moel in view of the vecto contol, next the oto flux F, is estimate. We, then, pesent the sliing moe theoy an esign the sliing moe contolles of oto flux an moto spee. Finally, we povie some conclusion emaks on the contol popose of I using sliing moe. The inuction machine is lagely use in inusty, mainly ue to its eliability an elatively low cost. The contol of the inuction machine (I) must take into account machine specificities: the high oe of the moel, the nonlinea functioning as well as the coupling between the iffeent vaiables of contol. In the secon stage fo my futue is inteest in the level contol in the couple tanks. Seveal eseaches have investigate the poblem of contolling liqui flow of a single o multiple tanks. The spee vaiations of the I cay the level egulation contol, the elation between spee an the flow of pumpe wate system. ISSN: Page 1

2 Intenational Jounal of Engineeing Tens an Technology (IJETT) - Volume4Issue5- ay 013 III ateials an ethos The inceasing eman of wate in ual zones an isolate sites mae that a gowing inteest is one to the utilization of photovoltaic (PV) geneato as enegy souce fo seveal moto-pumps. In fact, the ealization of autonomous, eliable pumping systems with a goo efficiency, gives a pactical an economical solution to the wate lack poblem in eset egions [9]. Since classical contol methos ae esigne at one nominal opeating point, they ae not able to espon satisfactoily to opeating point vaiations an loa istubance. They often fail to pefom satisfactoily une lage paamete o loa vaiations. The boost type DC-DC convetes ae use in applications whee the equie output voltage neee to be highe than the souce voltage. The contol of this type DC-DC convetes ae moe ifficult than the buck type whee the output voltage is Smalle than the souce voltage. The ifficulties in the contol of boost convetes ae ue to the non-minimum phase stuctue since, the contol input appeas both in voltage an cuent equations, fom the contol point of view the contol of boost type convetes ae moe ifficult than buck type.. Contol pinciple: Fig 1.Block Diagam of the photovoltaic wate-pumping system The figue 1 shows the popose stuctue. It is compose of an asynchonous moto powee by a photovoltaic geneato an stoage of batteies towas a voltage invete, contolle by a Sliing moe contol. A popula technique involves moeling only the switching elements of the powe stage. An equivalent cicuit fo these elements is eive an is calle the PW Switch oel whee PW is the abbeviation fo the pulse with moulate [9]. As shown in Figue 3, the powe stage has two inputs: the input voltage an the uty cycle. The uty cycle is the contol input, i.e., this input is a logic signal which contols the switching action of the powe stage an hence the output voltage. The thee majo components of the powe supply contol loop (i.e., the powe stage, the pulse with moulato, an the eo amplifie) ae shown in block iagam fom in Figue3 Fig.popose moel Diect cuent (DC-to-DC) convetes ae cicuits which convet souces of iect cuent (DC) fom one voltage level to anothe by changing the uty cycle of the main switches in the cicuits. Since DC DC convetes ae nonlinea systems, they epesent a big challenge fo contol esign. Fig 3 Powe supply contol loop components ain sola powee stock wateing system Components A typical sola-powee stock wateing System inclues a sola aay, pump, stoage tank an contolle in fig 3. ISSN: Page 13

3 Intenational Jounal of Engineeing Tens an Technology (IJETT) - Volume4Issue5- ay Sliing oe Contol Design The basic pinciple of sliing moe contol consists in moving the state tajectoy of the system towa a peetemine suface calle sliing o switching suface an in maintaining it aoun this latte with an appopiate switching logic [5]. This is simila to a fee-fowa contolle that povies the contol that shoul be applie to tack a esie tajectoy, which is in this case, the use-efine sliing suface itself. So, the esign of a sliing moe contolle has two steps, namely, the efinition of the aequate switching suface S (.) an the evelopment of the contol law o the switching logic U [6]. Fig 4. A typical sola powee stock wateing system. Dynamic oel of Inuction oto The fist pat of the global system investigate in this aticle consists mainly of a photovoltaic geneato (PV), a thee phase invete LI, an an inuction moto-pump.we suppose; the invete behaves as a pefect tansfeing powe ogan. Similaly, the chaacteistic of the geneato PV is suppose ieal that we can assimilate in a classic powe souce. is K 1 ( q 0) : is siqs us t T L iqs 1 i i pk u t Ls s 1 i s t T T s s qs qs q s i qs ( s p ) t T p s f 1 ( iqs ) C t JL J J With: L R R T R L L L L L L L s s s s, 1, K, s s s s Whee the electomagnetic toque is given in -q fame: s Cem p ( iqs ) L Whee, stato cuent components an leakage facto an poles ae use to contol the spee of the inuction moto. s Consie a nonlinea system which can be epesente by the following state space moel in a canonical fom (Slotine an Li, 1998): ( n x ) ( t) f ( x( t), t) g( x( t), t) u ( t) y( t) x( t). ( n1) T [ ( ) ( )... ( )] x x t x t x t Whee is the state vecto, f(x(t),t)an g(x(t),t) ae nonlinea function u is the contol input(t) is the extenal istubance. The objective of contol law u(t) to foce the system output y(t) in above equation an efeence signal. ( i) Tacking eo e( t) y ( t) y( t) an its fowa ( i) ( i) ( i) shifte value is efine as e ( t) y ( t) y ( t) x ( t) x ( t),( i 1,..., n 1) ( i) ( i) The esign of SC involves two tasks. The fist one is to the esign of SC involves two tasks. The fist one is to select the switching hype plane to pescibe the esie ynamic chaacteistics of the contolle system. The secon one is to esign the iscontinuous contol such that the system entes the sliing moe s(x, t) = 0 an emains in it foeve (Slotine an Li, 1998). n 1 s( x, t) ( ) e( t) t In which e x ( t) x( t) It emains to be shown that the contol law can be constucte so that the sliing suface will be eache. The sufaces ae chosen as functions of the eo between the efeences input signal an the measue Signals (Utkin, 1993).Then, a sliing hype plane can be epesente as s (x, t) = 0. Consie a Lyapunov function: 1 V s ISSN: Page 14

4 Intenational Jounal of Engineeing Tens an Technology (IJETT) - Volume4Issue5- ay 013 Fom Lyapunov theoem we know that if V& is negative efinite, the system tajectoy will be iven an attacte towa the sliing suface an emain sliing on it until the oigin is eache asymptotically (Buhle, 1986)... V s s The simplifie 1st oe poblem of keeping the scala s ( x, t ) at zeo can be achieve by choosing the contol Law u (t) [1]. A sufficient conition fo the stability of the system is 1 s s. t III SIULATION RESULT AND DISCUSSION The contolles esigne in Sections ae simulate using the ATLAB/Simulink softwae. The paametes of the system ae the paametes of the couple tanks appaatus which is use to implement the popose contol schemes. Fig 5. VI chaacteistic of PV moule Fig.7 simulation esult fo invete using sliing moe IV CONCLUSION A compaison between the PW base sliing moe contolle, PID an PI contolles fo c-c boost convete ae highlighte. Pefomance analysis fo contolling of c-c boost convete is evaluate in simulation une the intenal losses an input voltage vaiation. Sliing moe contolle an PI contolle have the same oveshoot voltage but voltage op is moe using PI contolle.pid contolle has maximum settling time as compae to sliing moe contolle an PI contolle.fou sliing moe contol schemes ae popose to assue autonomously the stability of the system. The pefomances of the contolle system ae stuie une vaiations in system paametes an in the pesence of extenal istubance. The simulation esults as well as the expeimental esults inicate that the popose contol schemes wok vey well an ae obust to change in the paametes of the system as well as to istubances acting on the system. The implementation esults inicate that the popose sliing moe contolle gave a best esult. A sliing moe contol metho has been popose an use fo the contol of an inuction machine. It has shown the obustness of popose contol. The spee contol opeates with enough stability an has stong obustness to paamete vaiations. V REFERENCES [1] K. Khan, an SK. Spugeonm, 006. Robust IO wate level contol in inteconnecte twin tanks using secon oe sliing moe contol Contol Eng Pact J. vol. 14, pp [] H. Pan, H. Wong, V. Kapila, an S. e Queioz Expeimental valiation of a nonlinea backstepping liqui level contolle fo a state couple two tank system, Contol Eng Pact J.vol. 40, pp. 13:7. Fig.6 Powe-V Chaatestics of PV moule [3] VI. Utkin, 1977 Vaiable stuctue systems with sliing moes, IEEE Tans Automat Contol, [4] vol., pp. 1. [5] VI. Utkin, 199 Sliing moes in contol an optimization, Belin: Spinge-Velag. ISSN: Page 15

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