Two-area Load Frequency Control using IP Controller Tuned Based on Harmony Search

Transcription

1 Research Journal of Applied Sciences, Engineering and Technology 3(12): , 211 ISSN: Maxwell Scienific Organizaion, 211 Submied: July 22, 211 Acceped: Sepember 18, 211 Published: December 26, 211 Two-area Load Frequency onrol using IP onroller Tuned Based on Harmony Search Sayed Mojaba Shirvani Boroujeni, Babak Keyvani Boroujeni, Mosafa Abdollahi and Hamideh Delafkar Deparmen of Elecrical Engineering, Boroujen Branch, Islamic Azad Universiy, Boroujen, Iran Absrac: In his sudy an opimal load frequency conroller for wo area inerconneced power sysem is presened o quench he deviaions in frequency and ie line power due o differen load disurbances. In classical LF problems, PI ype conrollers are used o conrol of sysem. Bu due o some disadvanages of he PI ype conrollers, he researchers are oward finding a beer conrol scheme. Alhough many differen advanced mehod have been carried ou o LF problem, bu he indusries are willing o use simple PI conrollers. In his scope, his paper presens IP ype conroller for LF problem. The parameers of he proposed IP conroller are uned using Harmony Search (HS) mehod. A wo-area elecric power sysem wih a wide range of parameric uncerainies is given o illusrae he proposed mehod. To show effeciveness of he proposed mehod and also comparison purposes, a PI ype conroller opimized by HS is also designed. The simulaion resuls visibly show he validiy of IP conroller in comparison wih PI conroller. Key words: Harmony search, IP conroller, load frequency conrol, wo area elecric power sysem INTRODUTION For large scale elecric power sysems wih inerconneced areas, Load Frequency onrol (LF) is imporan o keep he sysem frequency and he iner-area ie power as near o he scheduled values as possible. The inpu mechanical power o he generaors is used o conrol he frequency of oupu elecrical power and o mainain he power exchange beween he areas as scheduled. A well designed and operaed power sysem mus cope wih changes in he load and wih sysem disurbances, and i should provide accepable high level of power qualiy while mainaining boh volage and frequency wihin olerable limis. Many conrol sraegies for Load Frequency onrol in elecric power sysems have been proposed by researchers over he pas decades. This exensive research is due o fac ha LF consiues an imporan funcion of power sysem operaion where he main objecive is o regulae he oupu power of each generaor a prescribed levels while keeping he frequency flucuaions wihin pre-specifies limis. A unified uning of PID load frequency conroller for power sysems via inernal mode conrol has been proposed by Tan (21). In his sudy he uning mehod is based on he Two-Degree-of-Freedom (TDF) Inernal Model onrol (IM) design mehod and a PID approximaion procedure. A new discree-ime sliding mode conroller for load-frequency conrol in areas conrol of a power sysem has been presened by Vrdoljak e al. (21). In his sudy full-sae feedback is applied for LF no only in conrol areas wih hermal power plans bu also in conrol areas wih hydro power plans, in spie of heir non minimum phase behaviors. To enable full-sae feedback, a sae esimaion mehod based on fas sampling of measured oupu variables has been applied.the applicaions of arificial neural nework, geneic algorihms and opimal conrol o LF have been repored by Kocaarslan and am (25); Rerkpreedapong e al. (23) and Liu e al. (23). An adapive decenralized load frequency conrol of muli-area power sysems has been presened by Zribi e al. (25). Also he applicaion of robus conrol mehods for load frequency conrol problem has been presened by Shayeghi e al. (27) and Taher and Hemai (28). This sudy deals wih a design mehod for LF in a muli area elecric power sysem using IP ype conroller whose parameers are uned using HS. In order o show effeciveness of he proposed mehod, his IP conroller is compared wih a PI ype conroller whose parameers are uned using HS. Simulaion resuls show ha he IP conroller guaranees robus performance under a wide range of operaing condiions and sysem uncerainies. PLANT MODEL Figure 1 shows a wo-conrol area power sysem which is considered as a es sysem. The sae-space model of he sysem is as (1) (Wood and Wollenberg, 23). orresponding Auhor: Sayed Mojaba Shirvani Boroujeni, Deparmen of Elecrical Engineering, Boroujen Branch, Islamic Azad Universiy, Boroujen 1391

2 Res. J. Appl. Sci. Eng. Technol., 3(12): , 211 Fig. 1: Two-area elecric power sysem for LF sudies where, x Ax Bu y x u [ P P U, U ] D1, D2, 1 2 y [ y, y ] [ f, f, P ] ie x [ P P f P G1 T1 1 ie P P f ] G2 T2 2 (1) The parameers of model, defined as follow: ) : Deviaion from nominal value M= 2H : onsan of ineria D : Damping consan R : Gain of speed droop feedback loop T : Turbine Time consan T G : Governor Time consan G 1 : Firs area conroller : Second area conroller G 2 The ypical values of sysem parameers for nominal operaion condiion are as follow: T1 T2 3. TG1 TG2 8. TP1 TP2 2 R1 R KP1 KP2 12 B1 B K K 1; a 1 T where, he foonoe 1 indicaes firs area parameers and foonoe 2 indicaes second area parameers and he parameers of wo areas are considered equal. The objecives are Design G 1 and G 2 in Load Frequency onrol (LF). As referred before, many mehods have been carried ou o design hese conrollers so far. In his sudy IP ype conroller is considered o U i U i,ref s U o Fig. 2: Srucure of he IP conroller 1392

3 Res. J. Appl. Sci. Eng. Technol., 3(12): , 211 PI Fig. 3: Oupu of IP and PI regulaors wih he same damping coefficien () and he same band widh a he same sep inpu signal command conrol of sysem. A Mea heurisic opimizaion mehod named HS is used o uning he proposed conrollers. The goals are sudy he abiliy of IP conroller in Load Frequency onrol (LF) problem and also comparing he performances of IP and PI conrollers. In he nex secion, he proposed IP conroller is developed. IP conroller: As referred before, in his paper IP ype conrollers are considered for LF problem. Fig. 2 shows he srucure of IP conroller. I has some clear differences wih PI conroller. In he case of IP regulaor, a he sep inpu, he oupu of he regulaor varies slowly and is magniude is smaller han he magniude of PI regulaor a he same sep inpu (Sul, 211). Also as shown in Fig. 3, If he oupus of he boh regulaors are limied as he same value by physical consrains, hen compared o he bandwidh of PI regulaor he bandwidh of IP regulaor can be exended wihou he sauraion of he regulaor oupu (Sul, 211). Design mehodology: The proposed IP conroller performance is evaluaed on he proposed es sysem given in secion 2. The parameers of he IP conrollers are obained using HS. In he nex subsecion a brief inroducion abou HS is presened. Harmony search algorihm: Harmony Search (HS) algorihm is based on naural musical performance processes ha occur when a musician searches for a beer sae of harmony, such as during jazz improvisaion. The engineers seek for a global soluion as deermined by an objecive funcion, jus like he musicians seek o find musically pleasing harmony as deermined by an aesheic (Hong-qi e al., 28). In music improvisaion, each player sounds any pich wihin he possible range, ogeher making one harmony vecor. If all he piches make a good soluion, ha experience is sored in each variable s memory, and he possibiliy o make a good soluion is also increased nex ime. HS algorihm includes a number of opimizaion operaors, such as he Harmony Memory (HM), he harmony memory size (HMS, number of soluion vecors in harmony memory), IP he Harmony Memory onsidering Rae (HMR), and he Pich Adjusing Rae (PAR). In he HS algorihm, he harmony memory (HM) sores he feasible vecors, which are all in he feasible space. The harmony memory size deermines how many vecors i sores. A new vecor is generaed by selecing he componens of differen vecors randomly in he harmony memory. For example, onsider a jazz rio composed of saxophone, double bass and guiar. There exis cerain amoun of preferable piches in each musician s memory: saxophonis, {Do, Mi, Sol}; double bassis, {Si, Sol, Re}; and guiaris, {La, Fa, Do}. If saxophonis randomly plays {Sol} ou of {Do, Mi, Sol}, double bassis {Si} ou of {Si, Sol, Re}, and guiaris {Do} ou of {La, Fa, Do}, ha harmony (Sol, Si, Do) makes anoher harmony (musically -7 chord). And if he new harmony is beer han exising wors harmony in he HM, he new harmony is included in he HM and he wors harmony is excluded from he HM. This procedure is repeaed unil fanasic harmony is found. When a musician improvises one pich, usually he (or she) follows any one of hree rules: playing any one pich from his (or her) memory playing an adjacen pich of one pich from his (or her) memory playing oally random pich from he possible sound range (Hong-qi e al., 28). Similarly, when each decision variable chooses one value in he HS algorihm, i follows any one of hree rules: choosing any one value from HS memory (defined as memory consideraions) choosing an adjacen value of one value from he HS memory (defined as pich adjusmens) choosing oally random value from he possible value range (defined as randomizaion) The hree rules in HS algorihm are effecively direced using wo parameers, i.e., Harmony Memory onsidering Rae (HMR) and Pich Adjusing Rae (PAR). The seps in he procedure of harmony search are as follows (Verma e al., 21): Sep 1: Iniialize he problem and algorihm parameers. Sep 2: Iniialize he Harmony Memory (HM) Sep 3: Improvise a new harmony from he HM Sep 4: Updae he HM Sep 5: Repea Seps 3 and 4 unil he erminaion crierion is saisfied IP conroller adjusmen using HS: In his secion he parameers of he proposed IP conrollers are uned using HS. In opimizaion mehods, he firs sep is o define a performance index for opimal search. In his sudy he 1393

4 Res. J. Appl. Sci. Eng. Technol., 3(12): , 211 Table 1: Opimum values of and for IP conrollers Firs area IP parameers Second area IP parameers Table 2: Opimum values of and for PI conrollers Firs area PI parameers Second area PI parameers Table 3: 1% sep increase in demand of firs area ( D1 ) The calculaed ITAE IP PI Nominal operaing condiion Heavy operaing condiion Very heavy operaing condiion performance index is considered as (2). In fac, he performance index is he Inegral of he Time muliplied Absolue value of he Error (ITAE). ITAE d d 1 (2) I is clear o undersand ha he conroller wih lower ITAE is beer han he oher conrollers. To compue he opimum parameer values, a 1% sep change in DP D1 is assumed and he performance index is minimized using HS. I should be noed ha HS algorihm is run several imes and hen opimal se of parameers is seleced. The opimum values of he IP parameers are obained using HS and summarized in he Table 1. In order o comparison and show effeciveness of he proposed mehod, PI ype conroller opimized by HS is incorporaed for LF. The opimum value of he PI conrollers Parameers are obained and summarized in he Table 2. RESULTS AND DISUSSION The resuls are carried ou on he muli area es sysem wih he proposed IP and PI conrollers. Three operaing condiions are considered for simulaion as follows: Nominal operaing condiion Heavy operaing condiion (2%changing parameers from heir ypical values) Very heavy operaing condiion (4% changing parameers from heir ypical values) In order o demonsrae he robusness of he proposed mehod, The ITAE is calculaed following sep change in he demand of firs area ()P D1 ) a all operaing condiions (Nominal, Heavy and Very heavy) and resuls 2 Speed Deviaions (p.u.) Speed Deviaions (p.u.) Speed Deviaions (p.u.) (a) (b) (c) Fig. 4: Dynamic response )T 1 following sep change in demand of firs area () D1 ); a: Nominal b: Heavy c: Very heavy; Solid (IP conroller), Dashed (PI conroller) are lised a Table 3. Following sep change, he IP conroller has beer performance han he PI conroller a all operaing condiions. Fig. 4 shows ) T 1 a nominal, heavy and very heavy operaing condiions following 1 % sep change in he demand of firs area ()P D1 ). Each figure conains wo plos as solid line for IP conroller and dashed line for PI conroller. I is seen ha he IP conroller has beer performance han he oher mehod a all operaing condiions. 1394

5 Res. J. Appl. Sci. Eng. Technol., 3(12): , 211 ONLUSION This paper presened he applicaion of a new conrol scheme for LF problem. IP ype conroller has been successfully carried ou for LF problem. The parameers of he proposed IP conroller have been uned by using HS. The proposed IP conroller had significan prioriy raher han PI conroller. The simulaion resuls which have been carried ou on a wo-area elecric power sysem showed he viabiliy of IP conroller. The PI conroller is he mos commonly used conroller in he indusry and pracical sysems, herefore he paper s resuls can be used for he pracical LF sysems. REFERENES Hong-qi, L., K.Tai-hoon and X. Shao-Long,28. An improved PSO-based of heamony search for complicaed opimizaion problems. Inl. J. Hybrid Inform. Technol., 1(1): Kocaarslan, I. and E. am, 25. Fuzzy logic conroller in inerconneced elecrical power Sysems for loadfrequency conrol. Elecr. Power Energ. Sys., 27: Liu, F., Y.H. Song, J. Ma, S. Mai, Q. Lu, 23. Opimal load frequency conrol in resrucured power sysems. IEE Proc. Gen. Trans. Disr. 15(1): Rerkpreedapong, D., A. Hasanovic and A. Feliachi, 23. Robus load frequency conrol using geneic algorihms and linear mmarix inequaliies. IEEE T. Power Sys., 18(2): Shayeghi, H., H.A. Shayanfar and O.P. Malik, 27. Robus decenralized neural neworks based LF in a deregulaed power sysem. Elecric. Power Sys. Res., 77: Sul, S.K., 211. onrol of Elecric Machine Drive Sysems, John Wiley & Sons, Inc., Hoboken, New Jersey. Tan, W., 21. UniWed uning of PID load frequency conroller for power sysems via IM. IEEE T. Power Sys., 25(1): Taher, S.A. and R. Hemai, 28. Robus decenralized load frequency conrol using muli variable QFT mehod in deregulaed power sysems. Am. J. Appl. Sci., 5(7): Verma, A., B.K. Panigrahi and P.R. Bijwe, 21. Harmony search algorihm for ransmission nework expansion planning. IET Gen. T. Dis., 4(6): Vrdoljak, K., N. Peric and I. Perovic, 21. Sliding mode based load-frequency conrol in power sysems. Elecric. Power Sys. Res., 8(5): Wood, A.J. and B.F. Wollenberg, 23. Power Generaion, Operaion and onrol. John Wiley & Sons. Zribi, M., M. Al-Rashed and M. Alrifai, 25. Adapive decenralized load frequency conrol of muli-area power sysems. Elecric. Power Energ. Sys., 27: