Power System Transient Stability Analysis with High Wind Power Penetration

Transcription

1 Vol. () No., pp. - ISSN - Power Sytem Tranient Stability Analyi with High Win Power Penetration Amroune Mohamme, Bouktir Tarek Department of Electrical Engineering, Univerity of Setif, Algeria amrounemohamme@yahoo.fr tbouktir@gmail.com Abtract Some countrie i not have aequate fuel an water power reource, which le them to look for alternative way of generating electricity uch a win power, olar power, geothermal power an bioma power, calle renewable energy. Win energy i one of the mot available an exploitable form of renewable energy ue to their avantage. However the high penetration of win power ytem in the electrical network ha introuce new iue in the tability an tranient operation of power ytem. The majority of win farm intalle are uing fixe pee win turbine equippe with quirrel cage inuction generator (SCI). Therefore, the analyi of power ytem ynamic with the SCI win turbine ha become a very important reearch iue, epecially uring tranient fault. Thi paper provie an aement of win penetration effect on the power ytem tranient tability. The win generator coniere are the quirrel cage inuction generator (SCI), which i a fixe pee. Inex Term Power ytem, Squirrel Cage Inuction enerator (SCI), Win Penetration, Tranient tability, Critical Clearing Time (CCT) I. INTRODUCTION Win generator are primarily claifie a fixe pee or variable pee. Due to it low maintenance cot an imple contruction, quirrel cage inuction generator (SCI) i motly ue for win power generation []. SCI irectly connect to the gri an they on t have convertor like DFI. Becaue of lack of convertor an robut control proceure, SCI are more enitive to win pee variation rather than DFI an mechanical parameter like win turbine inertia contant an haft tiffne coefficient have remarkable impact on operation of thi kin of win generator. Moreover they are more enitive to fluctuation an fault in power ytem rather than DFI []. One of important iue engineer have to face i the impact of SCI win turbine penetration on the tranient tability of power ytem. Tranient tability entail the evaluation of a power ytem ability to withtan large iturbance an to urvive the tranition to another operating conition. Thee iturbance may be fault uch a a hort circuit on a tranmiion line, lo of a generator, lo of a loa, gain of loa or lo of a portion of tranmiion network []. A number of tuie have been conucte on power ytem tranient tability with high penetration of SCI bae win farm, but they have coniere imple network tructure [], [], []. In the preent work, the impact of SCI win farm intallation an penetration on tranient tability i emontrate uing the IEEE -bu ytem. Uing thi network, imulation ha been carrie out for two ifferent cae an ifferent penetration level uring three phae to groun fault: Cae : ingle SCI win farm ha been connecte to gri. Cae : the network ha been moifie by connecting two SCI win farm. Simulation reult how that win farm conit of contant pee win turbine in high penetration conition i remarkably influential in tranient tability. The paper i organize a follow. Section II briefly introuce the mathematical moel of power ytem an win generator. The Optimal Power Flow (OPF) formulation i preente in Section III. In ection IV, the etail cae tuie focuing on the impact of fixe pee gri-connecte win farm on IEEE- bu tet ytem are carrie out. Finally the concluion are ummarize in Section V. II. POWER SYSTEM MODELLIN A. Power Sytem Moelling The power ytem moel conit of ynchronou generator, tranmiion network an tatic loa moel, which are preente below. The machine claical electromechanical moel i repreente by the following ifferential equation []: Prof. Tarek Bouktir acknowlege upport from MESRS (Algeria), grant number J

2 Vol. () No., pp. - ISSN - i i i f P H P P Where: P i D mi ei Di D D i the generator amping coefficient, H i the inertia contant of machine expecte on the common MVA bae, P m i the mechanical input power an P e i the electrical output. The tranmiion network moel i ecribe by the teay-tate matrix equation: I bu bu bu () Y V () Where I bu i the injection current vector to the network, V bu i the noal voltage vector an Y bu i the noal matrix amittance. The electrical power of the i th generator i given by []: ng co ei i ii ij ij i j j P E C () Where i =,, ng i the number of generator. C ij = E i E j Y ij i the power tranferre at bu ij, E i the magnitue of the internal voltage, Y ij are the internal element of matrix Y bu an ii are the real value of the iagonal element of Y bu. The tatic moel of loa i repreente by loa amittance Y L efine by []: Pi - jq i Y Li = Vi B. Win enerator Moelling The fixe-pee, quirrel cage inuction generator (SCI) i connecte irectly to the itribution gri through a tranformer. There i a gear box which mace the generator pee to the frequency of the gri. During high win pee, the power extracte from the win i limite by the tall effect of the generator. Thi prevent the mechanical power extracte from the win from becoming too large. In mot cae, a capacitor bank i connecte to the fixe pee win generator for reactive power compenation purpoe. The capacitor bank minimize the amount of reactive power that the generator raw from the gri []. R v β ear Box ri () Fig.. Repreentation of the fixe pee inuction generator The Squirrel Cage Inuction generator moel i hown in Fig.. Where R repreent the tator reitance, X repreent the tator reactance; X m i the magnetizing reactance, while R r an X r repreent the rotor reitance an reactance, repectively. V R X X m Fig.. Equivalent circuit of the Squirrel Cage Inuction generator [] A tanar etaile two-axi inuction machine moel i ue to repreent the inuction generator. The relationhip between the tator voltage, rotor voltage, the current an the fluxe are given by the following equation []: v = -R i - ω λ q + λ () v q = -R i q +ω λ + λq v = = R i - g ω λ + λ v = = R i + g ω λ + λ V r r r r qr r qr r qr r qr V r = e- jwt V r Where V i the tator voltage while V r repreent the rotor voltage, λ an λ r are the tator an rotor flux repectively, while ω i the ynchronou pee. The rotor voltage i zero becaue the rotor ha been hort-circuite in the Squirrel cage inuction generator. The moel i complete by the mechanical equation a given below []: ωr = (Tm -T e ) () H H i the inertia contant; T m i the mechanical torque; T e i the electrical torque an ω r i the generator pee. III. OPTIMAL POWER FLOW FORMULATION The OPF problem i coniere a a general minimization problem with contraint an can be written in the following form [], []: Minimize f ( x, u ) () Subject to g( xu, ) () () h( xu, ) () Where f(x,u) i the objective function; g(x,u) i the equality contraint an repreent typical loa flow equation; h(x,u) i R r X r

3 International Electrical Engineering Journal (IEEJ) Vol. () No., pp. - ISSN - the ytem operating contraint an x i the vector of tate variable. The objective function for the OPF reflect the cot aociate with generating power in the ytem. The objective function for the entire power ytem can then be written a the um of the fuel cot moel for each generator: f N f () i i Where f i i the fuel cot of the i th generator The fuel cot curve i moele by quaratic function a: f a b P c P () i i i i i i Where a i, b i, an c i are cot coefficient of the i th generating unit hown in the Appenix. The function g an h are the equality an inequality contraint to be atifie while earching for the optimal olution. The function g repreent the equality contraint that are the power flow equation correponing to both real an reactive power balance equation, which can be written a []: P V, P P () i i gi Q V, Q Q () i i gi h i the ytem inequality operation contraint that inclue []: P P P () min max gi gi gi generate. It ue mutation operation a a earch mechanim. Thi operation generate new parameter vector by aing a weighte ifference vector between two population member to a thir member. In orer to increae the iverity of the parameter vector, the croover operation prouce a trial vector which i a combination of a mutant vector an a parent vector. Then the election operation irect the earch towar the propective region in the earch pace. In aition, the bet parameter vector i evaluate for every generation in orer to keep track of the progre that i mae uring the minimization proce. The above iterative proce of mutation, croover an election on the population will continue until a uer-pecifie topping criterion, normally, the maximum number of generation or the maximum number of function evaluation allowe i met. The proce i aume to have converge if the ifference between the bet function value in the new an ol population, an the itance between the new bet point an the ol bet point are le than the pecifie repective tolerance []. IV. SIMULATION RESULTS Thi ection preent computer imulation tuie with program evelope in MATLAB oftware verion. to emontrate the tranient performance of the power ytem with high win power integration. The Critical Clearing Time (CCT) i ue a inice to evaluate tranient tability an the IEEE -bu tet ytem hown in Fig. i employe to conuct the tranient tability imulation. Detaile parameter of thi ytem can be foun in []. A win farm bae on Fixe Spee Inuction enerator (FSI) i ue an the FSI parameter are outline in the Appenix. Q Q Q () min max gi gi gi Where P gi an Q gi are the active an reactive power generation at i th bu; P i an Q i are the active an reactive power eman at i th bu; P i an Q i are the active an reactive power injection at i th bu. Several metho have been employe to olve thi problem, e.g. graient metho, Linear programming metho an quaratic programming. However all of thee metho they may not be able to provie optimal olution an uually getting tuck at a local optimal []. New optimization technique uch a genetic algorithm, particle warm optimization, Artificial Ant Colony algorithm, an Differential Evolution Algorithm are recently introuce an alo applie in the fiel of power ytem. In thi paper Differential Evolution Algorithm (DEA) i ue. Differential Evolution i a irect earch metho uing operator: mutation, croover an election. The algorithm ranomly chooe a population vector of fixe ize. During each iteration of algorithm a new population of ame ize i

4 Angle rotorique relatif, egree International Electrical Engineering Journal (IEEJ) Vol. () No., pp. - ISSN - Fig.. Single line iagram of the IEEE -bu ytem cot($/h) A. Cae : Single SCI win farm In thi cae the SCI win farm of MW ha been connecte to bu an bu eparately (Figure ). The SCI wa intalle in a ite that ha the bet potential in therm of the reource itelf, contruction an operation an maintenance logitic a well a interconnection an potentiel permiing iue uch a willife ampct an local politic []. The Optimal Power Flow reult obtaine with Differential Evolution Algorithm (DEA) with an without of win farm i lite in Table. Accoring to thi table connecting the win farm at bu will be a better option in term reuction in the total cot an power loe. W W A iturbance in the form of a three phae to groun fault i occur at t = econ at bu, cleare by opening the line connecting the noe. The ynamic analyi of gri connecte SCI nee to know about the Critical Clearing Time (CCT) of SCI, which etermine it tranient tability. If the CCT i much lower than the time etting of protective evice normally intalle in network, the ytem i ai to be table []. The Figure an how the ynamic repone of all machine for Fault Clearing Time (FCT) equal to m an m repectively. Thee Figure how that the Critical Clearing Time (CCT) improve after the introuction of the win farm of SCI type. For FCT = m, the ytem with Win Farm (WF) at bu ( ) remain table an can return to teay tate finally. However, the ytem with win farm at bu ( ) i untable. Another imulation have been performe for ifferent fault location in IEEE -bu ytem, in orer to know the effect of SCI win farm location on tranient tability. The reult from the cae tuy are preente in Table. The comparative reult have hown that the location of win turbine ha an effect in tranient tability of power ytem. In our cae the inertion of a win farm at bu i better than it inertion at bu without win farm ** *win farm at bu win farm at bu **** éolienne au jb éolienne au jb an éolienne Fig.. Single line iagram of the moifie IEEE -bu ytem TABLE : OPF RESULTS WITH AND WITHOUT WIND FARMS BUS P (MW) Without win farm P (MW) With win farm at bu P (MW) With win farm at bu t, ec Fig.. Rotor angle ifference of all machine (FCT= m) P lo... Total...

5 Angle rotorique relatif, egree International Electrical Engineering Journal (IEEJ) Vol. () No., pp. - ISSN - **** éolienne without au win jb farm éolienne au jb ** *win an farm éolienne at bu win farm at bu t, ec Fig.. Rotor angle ifference of all machine (FCT= m) Fig.. Power generation with win farm at bu TABLE : CCT WITH AND WITHOUT WIND FARMS Faulte bu Open line CCT without win farm (m) CCT with win farm at bu (m) CCT with win farm at bu (m) Fig.. Power generation with win farm at bu In orer know the impact of win penetration level on the power ytem Critical Clearing Time, the analyi ha been carrie out on %, %, % an % win penetration level bae on the total power require (. MW). Penetration level i efine a the ratio of capacity of win electric generator to capacity of alternator. The optimal active power generate by all generator when SCI win farm i connecte to bu an to bu are hown in Fig. an Fig. repectively. The variation of CCT for the fault at bu with opening the line i hown in Figure. From thee Figure, it can be een that the ytem tranient tability can be improve by improving penetration level of SCI win turbine. Fig.. CCT variation with win farm (fault at bu ) B. Cae : Two SCI win farm In thi cae the two SCI win farm have been connecte to bu an bu imultaneouly. Both farm generate MW. Table III hown the total cot obtaine with three penetration level cenario. Accoring to thi table the total cot i low when the penetration level of win farm i high at bu an low at bu (cenario ). A three-phae hort circuit ha been imulate on eferent electe bue for the three previou cenario. The

6 Vol. () No., pp. - ISSN - itribution of power generation between win farm ha an effect on tranient tability of power ytem a hown in Table IV. In our tuy the CCT i more improve when the penetration level of win farm i high at bu an low at bu (cenario ). TABLE : OPF RESULTS FOR DEFERENT SCENARIOS Total cot ($/h) Scenario % %. Scenario % %. Scenario % %. preliminary concluion an comment can be ummarize a follow: An optimal integration, location an utilization of SCI type win generator to the power ytem improve the tranient tability; Win power plant affect voltage level an power flow in the network. Thee effect can be beneficial to the ytem, epecially when win power plant are locate near loa center. The location an number of SCI bae win turbine ha an effect on tranient tability of power ytem; The increae of penetration level of win generation SCI type increae the power ytem Critical Clearing Time; The itribution of power between SCI win farm ha an effect on tranient tability of power ytem. Appenix TABLE : POWER ENERAION LIMITS AND COEFFICIENTS Faulte bu Fig.. Power generation for eferent cenario TABLE I. Ope n line CCT FOR DEFERENT SCENARIOS CCT (m) for Scenario CCT (m) for cenario CCT (m) for cenario V. CONCLUSION The impact of increae penetration of fixe pee win generator on power ytem tranient tability i icue in thi paper. Accoring to the imulation reult, ome Cot Coefficient P MIN (MW) P MAX (MW) BUS a b c TABLE : INDUCTION TURBINE MODEL PARAMETRS Stator reitance (R ) Rotor reitance (R r) Stator reactance (X ) Rotor reactance (X r) Magnetizing reactance (X m) Inertia contant (H) REFERENCES. pu. pu. pu. pu. pu [] M. Muyeen, et al., "Tranient Stability Analyi of Win enerator Sytem with the Conieration of Multi-Ma Shaft Moel," in International Conference on Power Electronic an Drive Sytem,PED., pp. - [] L. Lin, Y. Zhang, Y. Yang, "Tranient characteritic of the griconnecte win power farm with DFI an SCI," Electric Utility Deregulation an Retructuring an Power Technologie, Thir International Conference on, April, pp. -. [] K. Folly, "Impact of Fixe an Variable Spee Win enerator on the Tranient Stability of a Power Sytem Network," in IEEE/PES Power Sytem Conference an Expoition,. PSCE ', Univ. of Cape Town, Cape Town, - March, pp. -.

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