Quarter-Hourly Generation Scheduling of Hydropower Systems Considering Peak Saving Demands among Multiple Provincial Power Grids in Central China

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1 Inernaonal Journal of Elecrcal Enery, Vol. 3, No. 3, Sepember 2015 Quarer-Hourly eneraon Scheduln of Hydropower Sysems Consdern Pea Savn Demands amon Mulple Provncal Power rds n Cenral Chna Pen Lu1, Janzhon Zhou1,2, Chunlon L1, Chao Wan1, and L Mo1 1 School of Hydropower and Informaon Enneern, Huazhon Unversy of Scence and echnoloy, Wuhan, Chna 2 Hube Key Laboraory of Dal Valley Scence and echnoloy, Wuhan, Chna Emal: {penl_hae, jz.zhou, lchunlon, palawchus, mol}@hus.edu.cn Absrac Quarer-Hourly eneraon scheduln of hydropower sysems (QHSHS) s a ypcal nonlnear opmzaon problem o maxmum he oal pean capacy benefs whle smulaneously meen he rd reuremens and oher hydraulc and elecrcal consrans. In hs paper, o realze he coordnaon of hydropower saons and power rds, he mnmum varance of resdual load seres whch are obaned by subracn hydropower eneraon from he ornal forcasn load of each power rd, s used as he opmzaon objecve of QHSHS problem. On hs bass, consdern he complemenary feaures amon mulple power rds, he adapve dfferenal bee colony opmzaon alorhm (ADBCO) wh heursc consrans reparn sraees s proposed o opmze he power allocaon of he hydropower saons n Cenral Chna wh he consrans such as elecrcal power ransmsson proporon, power balance of hydropower saons and power ransmsson lm of HVDC ransmsson lne consdered. he smulaon resuls show ha, he eneraon plan obaned by proposed mehod can balance response o he demands of mulple rds, and he proposed mehod also reveals sron praccably. (CC), whch covers Chonn cy, Hube, Hunan, Henan, Janx and Schuan provnces, becomes he leadn reon for he hydropower developmen and enery-savn eneraon dspachn n Chna. he hydropower of CC accounn for 42% of he oal nsalled power capacy, whch are manly concenraed n Schuan, Hube and Hunan provnces (he dsrbuon of he lare hydropower saons commanded by he Cenral Dspachn Auhory (CDA) [3] of CC and Sae rd (S) s shown n F. 1). o absorb he rch waer power resources of CC, some HVDC ransmsson lnes have been bul one afer he oher, and he spare hydropower s ransmed o he Eas Chna, Souh Chna and Norhwes Chna usn hese HVDC ransmsson lnes (he sech map of CC wh HVDC ransmsson lnes s shown n F. 2). In he real-world enneern, he hydropower saons ha commanded by he CDA of CC and S, such as hree ores, ezhouba, Xluodu, Xanjaba, Jnpn and uand, need o ransm he elecrc power o mulple power rds, and mae her power oupus rapdly response o he pea shavn reuremens of power rds wh he dfferen load characerscs. he radonal scheduln mode and power ransmsson way of hydropower saons enerally dspach elecrc power only for a snle provncal power rd, alhouh here have been some research on uarer-hourly eneraon scheduln of hydropower sysems (QHSHS) over he pas few years [4], [5], here are few sudes nvolved power allocaon amon mulple power rds, especally for such an nerconneced larer power sysem. herefore, n hs paper, o deal wh he QHSHS problem of CC consdern pean savn demands amon mulple provncal power rds, a nd of heursc mehod wh adapve consran repar sraey was proposed. Index erms uarer-hourly eneraon scheduln, hydropower sysems, pea savn demands, mulple power rds I. INRODUCION Hydropower s one of he mos mporan renewable and clean enery sources, whch plays a prmary role n solvn our enery crss caused by he ncreasn scarcy of fossl fuel resources, and can mnmze he polluon emssons effecvely [1]. Currenly, wh he radual promoon of Wes-Eas Power ransmsson projec and Chna s proposed 12h Fve-Year Plan on elecrc power, he planned 13-hydropower bases of Chna have been compleed one afer he oher, and Chna's hydropower also have radually sepped no he new era of lare-scale jon scheduln and spare hydropower ner-provncal absorbn [2]. Under he new developmen suaon, he Cenral Chna rd II. A. Objecve Funcon he objecve funcon for pea operaon and elecrc power ner-provncal coordnaon dsrbuon of Manuscrp receved June 3, 2015; revsed Auus 18, Inernaonal Journal of Elecrcal Enery do: /joee PROBLEM FORMULAION 145

2 Inernaonal Journal of Elecrcal Enery, Vol. 3, No. 3, Sepember 2015 cascade hydropower plans amon mulple power rds, can be descrbed as follows: Obj : F Mnw S 1 (1) I 1 2 S ( R R ) and R L p, L ( )/ max 1 1 where F s he oal varance of resdual load seres of mulple power rds. s he number of rds. s he oal dspach perods. I s he he number of saons. S Yalon Rver Schuan Provnce Jnsha Rver 5 6 Dadu R. Jaln R. Ybn Hube Provnce Wu R. s he varance of resdual load seres of h rd. w s he weh coeffcen whch reflecs he snfcance of h rd, and he value of whch usually s se as 1/. R s he resdual load of h rd a h nerval. he ornal load of h rd a h nerval, and L s L max denoes he maxmum load value of h rd. p, s he power oupu of h saon a h nerval whch s ransmed o h rd. Yanze Rver Ychan Qn Rver Hunan Provnce Yuan Rver Fure 1. he opoloc srucure of hydropower plans n CC. Plan leend: 1 Jnpn I 2 Jnpn II 3 uand 4 Er an 5 Xluodu 6 Xanjaba 7 hree ores 8 ezhouba 9 Shubuya 10 eheyan 11 aobazhou 12 Sanbanx 13 Bash 14 uoou 15 Wuanx Larer Run-of-Rver Lne leend: Norhwes Chna Lne 9: 500V HVDC 3000MW Lne 1 hree ores - Chanzhou Cy Lne 2 hree ores - Shanha Cy Lne 3 ezhouba Shanha Cy Lne 4 hree ores Huzhou Cy Lne 5 Xanjaba Shanha Cy Lne 6 Xluodu lef ban Jnhua Cy Lne 7 Xchan Cy Suzhou Cy Lne 8 Xluodu rh ban Conhua Cy Lne 9 Deyan Cy Baoj Cy Power ransmsson drecon and lmaon Cenral Chna Chonn Schuan 1,2,3,4,5, Lne 8: 800V UHVDC 6400MW Henan 5000 Hube 7,8,9,10, Hunan 12,13,14,15 Souh Chna Lne 1: 500V HVDC 3000MW Lne 2: 500V HVDC 3000MW 3000 Janx Lne 3: 500V HVDC 1200MW Lne 4: 500V HVDC 3000MW Lne 5: 800V UHVDC 6400MW Lne 6: 800V UHVDC 6400MW Lne 7: 800V UHVDC 7200MW Eas Chna Fure 2. he sech map of CC wh HVDC ransmsson lnes. B. Consrans he QHSHS problem should sasfy he follown eualy and neualy consrans: Hydraulc connecon: I, Q 1, S1, R, (2) 1, 1, Waer balance consran: V V ( I Q S ) (3),, 1,,, Reservor sorae volume and waer dschare consran: V V V and Q ( Q S ) Q (4),,,,,,, 2015 Inernaonal Journal of Elecrcal Enery 146

3 Inernaonal Journal of Elecrcal Enery, Vol. 3, No. 3, Sepember 2015 Inal and ermnal reservor sorae volumes consran: Ben End,0 and, V V V V (5) Hydropower saon oupu lm: P P P and P P P (6),,,,, 1 Specfed elecrcal power ransmsson proporon consran of hydropower saon: p, P, (7) 1 1 Power balance of hydropower saon: p, P, (8) 1 Power ransmsson lm of HVDC ransmsson lne: NL NL NL and NL NL NL (9) l l,, l l,, l,, 1 l where I,, Q,, S,, R,, V, and P, are nflow, waer release, spllae, local nflow, reservor sorae and power oupu of h saon a h nerval, respecvely. s he me delay beween (-1)h and h saon. 1, V, and V,, Q, and Q,, P, and P, are he mnmum and maxmum values of reservor sorae volume, waer dschare and power oupu, respecve. Ben End V and V are he nal and ermnal reservor sorae lms., P s he ramp rae lm of h saon. p s he allocaed power of h saon ransms o h rd a h nerval, and s he specfed elecrcal power ransmsson proporon. NL,, l s he power of lh HVDC ransmsson lne ransms o h rd a h nerval. NL l and NL l are he lower and upper lms of lh HVDC ransmsson lne, respecvely. NLl s he maxmum amplude of power ransmsson beween adjacen me. III. SOLUION SRAEY A. Ouflow/Load Economc Dspachn Ouflow/Load economc dspachn s a basc and mporan par n QHSHS. enerally, when he ouflow, waer head and un commmen of he hydropower saon a one nerval are predeermned, he ouflow economc dspach (ED) becomes he problem of maxmum power oupu, and hs problem can be solved by usn DP alorhm [6]. he recurson formula of DP for ED problem s defned as follows: * * N ( Q, H) max[ N ( Q, H) N 1 ( Q 1, H )] Q 1 Q Q, 1,2,, n * N0 ( Q0, H ) 0 Q0 (10) where sae varable = number of eneran uns. s he power oupu of h un. Sae varable Q = he oal ouflow of uns 1 o. Decson varable Q = he ouflow of h un. N N * ( Q, H ) s he opmal power * oupu. N0( N0, H ) s he nal boundary condon, whch values 0. Appln he above mehod o e he opmal ouflow dspachn soluons under he dfferen waer head and ouflow combnaon, and savn he soluon ses o call when needed. he load economc dspachn problem can be solved by usn dchoomy [5] based on he above opmal ouflow dspachn resuls. B. Inal Elecrc Power and Enery Balance for Hydropower Saon o mae he power oupu of he hydropower saon follow he varyn load of he rds, he load sheddn mehod s used o realze he nal power elecrc uany allocaon of he saon n hs paper. he dealed process s shown as follows: Supposn he elecrcal uany of h saon,max ransms o h rd s E, and he lm of p, s p, and he resdual load seres of h rd s 1 2 LR, LR,..., LR. Sep 1: Fnd he maxmum load 1 2 max LR, amon LR, LR,..., LR, and calculae he nal elecrc power seres of h saon ransms o h rd wh, max,max p, =max LR LR p,0. Sep 2: Calculae he oal ransmsson enery wh E = p *. If E E, urn o sep 4. Oherwse, 1, urn o sep 3. Sep 3: If E E, hen se p, =max p, dela, 0 where dela=( E E ) /. Oherwse, f E se,,,max, E, hen p =mn max p dela, 0, p. urn o sep 2. Sep 4: Oupu he elecrc power seres,1,2, p, p,..., p of h saon ransms o h rd. C. Proposed Heursc Random Searchn Approach for QHSHS Problem Solvn he proposed mehod manly ulzes he complemenary propery of dfferen rds n load characersc, o realze he power elecrc uany opmal allocaon of he saon amon mulple rds. he dealed solvn process s shown as follows: 1) Inal soluon eneran Sep 1: Consdern he upsream and downsream hydraulc connecon of cascade hydropower saons, and calculan he averae avalable waer of he hydropower saon durn he scheduln perod based on he waer balance euaon Inernaonal Journal of Elecrcal Enery 147

4 Inernaonal Journal of Elecrcal Enery, Vol. 3, No. 3, Sepember 2015 p, and P,,mn =max P, p,,0 1, 1, (13) 3) Heursc consrans reparn sraees When populaon nalzaon or updan operaon have been mplemened, he eneraed soluon may no mee he consrans such as (5)-(9), so s necessary o find some effecve measures o handle hese complex consrans. Sep 1: Accordn o he me order, checn he elecrc power seres p,1, p,2,..., p, ha h saon Sep 2: Calculan he power eneraon capacy E0 of h plan wh he ouflow economc dspachn mehod menoned n Ouflow/Load economc dspachn, and esman he maxmum oupu capacy P max of he plans under he averae waer head he nex day. Sep 3: Calculan he elecrcal uany E ha h P,,max =P max plan ransms o h rd wh (11), and dvdn P max no peces. Especally, f he elecrc power ha h saon ransms o h rd needs o pass he lh HVDC ransmsson lne, hen P max can be calculaed by (12). E = E0 and P,max =Pmax / P,max =mn Pmax /, NLl ransms o h rd n urn. he recevn power oupu lm of h rd a h nerval s deermned by (14). If P, [ P,,mn, P,,max ], hen se o he border. Meanwhle, (11) (12) f he elecrc power ha h saon ransms o h rd needs o pass he lh HVDC ransmsson lne, hen P,,mn and P, max can be calculaed by (15). Sep 4: Wh E as he balanced elecrcal uany and P max as he oupu lm, calculan he elecrc power seres p,1, p,2,..., p, by usn he load,mn,mn P, = max P,, p, 1 p, P 1 1,,max,max P, = mn P,, p, 1 p, P 1 1, sheddn mehod menoned n Inal elecrc power and enery balance for hydropower saon, and ulmaely en roup of elecrc power seres. Accumulae hese roup of elecrc power seres wh P,mn = max P,mn, p, 1 p, P, NLl,, 1 NLl,, 1 1,,max p, 1 p, P, NLl,, 1 NLl = mn P,,max, P, 1 1, P, p,, 1, and enerae nal power 1 oupu process P,1, P,2,...,P, of h plan. 2) Power oupu readjusn Based on he nal soluon, readjusn power oupu process of h plan by ADBCO alorhm [5]. Sep 1: Se rd 1. Sep 2: Fxed he power oupu process of he rds excep for h rd, and readjus he power oupu process of h rd wh he objecve ha shown n (1). Accordn o he specfed elecrcal power ransmsson proporon commands n (11), he opmzaon objecve of h rd s smplfed as a uadrac funcon wh p,1, p,2,...,p, decson varables. In he wh E = p, *. If E -E ( s he devaon 1 marn), hen he he procedure of consran handln ben, and dvde he enery devaon E E -E no N eual peces by dela E / N. Sep 3: enerae a se of random seuence r1, r2,..., rn,..., rn wh rn rndr (n), where rndr (n) s he random neer wh doman [1, ]. Amendn he recevn power oupu ha h saon ransms o h rd wh P,r =P,r dele, n 1, 2,..., N. n n Sep 4: Repea he above hree sep unl all of he consrans are sasfed. Sep 3: If, se = 1, urn o sep 2. ABLE I. HE RANSMISSION PROPORIONS OF ELECRICAL POWER FROM HYDROPOWER PLANS FOR PROVINCIAL POWER RIDS Hube Hunan Cenral Chna rd Janx Henan Schuan 1, 2, , 10, 11 12, 13, 14, % 50% 7% 30% 18.48% 100% 13.20% 7.92% 4.40% 100% 2015 Inernaonal Journal of Elecrcal Enery (15) Sep 2: Calculae he oal recevn enery of h rd crcumsances, he ADBCO alorhm s appled o solve hs smple opmzaon problem wh he consrans such as (5)-(9) consdered. he nal opmzaon reon [ P,,mn, P,,max ] of ADBCO can be deermned by (13). Saon (14) 148 Chonn 20.35% 50% Eas Chna rd Souh Chna rd uandon Yunnan 59.30% 35% 70% 40% 44% 35% 16% 23%

5 Inernaonal Journal of Elecrcal Enery, Vol. 3, No. 3, Sepember 2015 IV. parameer of proposed ADBCO, we don need o se oo many parameers for. In hs sudy, he ADBCO conrol parameers for QHSHS problem are seleced as follows: ndvduals number NP s se o 30, maxmum eraon number max s se o 100, abandon me of food sources s se o 10. CASE SUDY A. Parameers Sen In hs secon, we apply he proposed heursc mehod o solve QHSHS problem of CC consdern pean savn demands amon mulple provncal power rds. We choose he acual worn condon for ypcal day on Aprl, 2014 as smulaon example, and he ransmsson proporons of elecrcal power from hydropower plans for provncal power rds are shown n able I. he model s mplemened by java code on an Inel dual core 2.60Hz personal compuer. Usually, he avalably of an alorhm s affeced by parameer sen. However, due o he adapve B. Smulaon Resul and Analyss Wh he above nal condons and parameers sen, proposed heursc mehod s appled o solve QHSHS problem whle consdern varous consrans, and 20 mes ndependen smulaons are carred ou o e fnal opmal soluons. ABLE II. HE PEAK-VALLEY LOAD DIFFERENCE AND MEAN SQUARE DEVIAION OF PROVINCIAL POWER RIDS Power rd Hube Hunan Schuan Chonn Janx Henan Eas Chna uandon Yunnan nal Pea-valley load dfference (MW) pea shavn decreased percenae rane (%) afer nal Mean suare devaon of load (MW) pea shavn decreased percenae afer rane (%) Fure 3. he pean savn resuls and hourly recevn power oupu process of rds. he correspondn pean savn resuls of rds are presened n F. 3 and able II. F. 3 presens he pean savn resuls and hourly recevn power oupu process of rds, whch reflecs ha he power oupus of saons a each nerval can mee he needs of each power rd, and power ransmsson lms amon dfferen rds have been sasfed well. Afer he pea savn operaon of he hydropower plans, he load flucuaon of each 2015 Inernaonal Journal of Elecrcal Enery rd decreased evdenly, and he saonary of he resdual load mproved effecvely. o demonsrae he feasbly and effcency of proposed mehod n solvn QHSHS problem, he dealed dspachn resuls abou he pea-valley load dfference and mean suare devaon of provncal power rds are ven n able II. From able II, we can now ha he resdual load of power rds are level off afer pea savn operaon, 149

6 Inernaonal Journal of Elecrcal Enery, Vol. 3, No. 3, Sepember 2015 especally for Hube, Hunan, Schuan and Chonn provnce, he decreased rane percenae of pea-valley load dfference are 68%, 80%, 69% and 67%, respecvely. he mean suare devaon reflecs he saonary of he load n some deree, he daa ven n able II shows ha he decreased rane percenae of mean suare devaon are 67%, 89%, 79%, 40%, 44%, 16%, 39%, 41% and 65%, respecvely, whch demonsrae ha he power oupu allocaon plan of hydropower can reduce he pea-valley load dfference of he rd, and a he same me larely realze he relavely sable of load pea and valley semen hrouhou he day. Overall, he eneraon plan obaned by proposed mehod can balanced response o he demands of mulple rds, and decrease he flucuaon of resdual load effecvely. he proposed mehod reveals sron praccably. V. CONCLUSION In hs paper, a nd of heursc mehod wh adapve consran repar sraey whch based on BCO alorhm was proposed o deal wh he QHSHS problem of CC consdern pean savn demands amon mulple provncal power rds. he smulaon resuls ndcae ha, he pea-valley load dfference and load flucuaon of each rd decreased evdenly, and he saonary of he resdual load mproved effecvely by means of he pea savn operaon of he hydropower plans. he eneraon plan obaned by proposed mehod can balanced response o he demands of mulple rds, and decrease he flucuaon of resdual load effecvely. herefore, we provde an effecve approach for solvn he problems of QHSHS and spare hydropower nerprovnce absorbn. ACKNOWLEDMEN hs wor s suppored by he Sae Key Proram of Naonal Naural Scence of Chna (ran No ) and he Naonal Naural Scence Foundaon of Chna (No ). REFERENCES [1] R. Zhan, J. Zhou, H. Zhan, X. Lao, and X. Wan, Opmal operaon of lare-scale cascaded hydropower sysems n he upper reaches of he Yanze Rver, Chna, Journal of Waer Resources Plannn and Manaemen, vol. 140, pp , [2] J. Shen, C. Chen, X. Wu, X. Chen, W. L, and J. Lu, Opmzaon of pea loads amon mulple provncal power rds under a cenral dspachn auhory, Enery, vol. 74, pp , [3] C.. Chen, J. J. Shen, X. Y. Wu, and K. W. Chau, Operaon challenes for fas-rown Chna s hydropower sysems and respondence o enery savn and emsson reducon, Renewable and Susanable Enery Revews, vol. 16, pp , [4] J. Wan, S. Lu, and Y. Zhan, Quarer-Hourly operaon of lare-scale hydropower reservor sysems wh prorzed consrans, Journal of Waer Resources Plannn and Manaemen, vol. 141, pp , [5] P. Lu, J. Zhou, C. Wan, Q. Qao, and L. Mo, Shor-erm hydro eneraon scheduln of Xluodu and Xanjaba cascade hydropower saons usn mproved bnary-real coded bee colony opmzaon alorhm, Enery Converson and Manaemen, vol. 91, pp , [6]. K. Su,. A Nash, and Z. K. Shawwash, A praccal hydro, dynamc un commmen and loadn model, IEEE ransacons on Power Sysems, vol. 16, pp , Pen Lu has a Bachelor s deree n hydraulc and hydropower enneern from Huazhon Unversy of S& (HUS), Wuhan, Chna n He s a PhD Canddae, where hs opc s relaed o hydropower sysem, opmzaon problem and economc operaon. He devoes o a ey projec funded by he Naonal Naural Scence Foundaon of Chna (NSFC) on hydropower sysem operaon opmzaon of he Yanze Rver ( ). Mr. Lu s man research neress nclude waer resource manaemen, hydropower sysem operaon opmzaon, economc operaon and decson suppor sysem. Janzhon Zhou s a professor n hydropower sysem a School of Hydropower & Informaon Enneern of Huazhon Unversy of S& (HUS), Wuhan, Chna. He s he cadres of several Naonal ey basc research projecs: he lon-erm ecolocal effecs of mporan bolocal resources n he Yanze Rver Basn (NO ), he heory and mehod on complex sysem scheduln of reservor roups n he upper reaches of he Yanze Rver (NO ) and he wn-wn sraey research on Hydropower enery compeon n he elecrcy mare (NO ). Prof. Zhou s man research neress nclude he heory and he mehod of hydropower enery and s analyss, power eneraon process conrol and hh-performance newor and nformaon sysem. Chunlon L has a Bachelor s deree n hydraulc and hydropower enneern from Huazhon Unversy of S& (HUS), Wuhan, Chna n He s a PhD Canddae, where hs opc s relaed o hydropower eneraon manaemen and waer resources plannn. He s a major member n he ey projec on hydropower sysem opmzaon of he Yanze Rver ( ), funded by he Naonal Naural Scence Foundaon of Chna (NSFC). Mr. L s man research neress nclude waer resource manaemen, nellen opmzaon and decson suppor sysem. Chao Wan has a Bachelor's deree n hydraulc and hydropower enneern from Huazhon Unversy of S& (HUS), Wuhan, Chna n He s a PhD Canddae, where hs opc s relaed o hydropower sysem, opmzaon problem and decson suppor sysem. He devoes o a ey projec funded by he Naonal Naural Scence Foundaon of Chna (NSFC) on hydropower sysem operaon opmzaon of he Yanze Rver ( ). Mr. Wan s man research neress nclude waer resource manaemen, hydropower sysem operaon opmzaon, nellence alorhms and decson suppor sysem. L Mo s an assocae professor n hydropower sysem a School of Hydropower & Informaon Enneern of Huazhon Unversy of S& (HUS), Wuhan, Chna. She s he cadres of he Naonal Naural Scence Foundaon research projecs: Symboss Mechansm and Symboss Unon Prof Sharn Sraees of Mul-owner Cascade Hydro Plans (No ) and Rs Sharn Opmal Operaon and Dfferenal ames Counermeasures of Mul-owner Hydro Plans under Uncerany Inflow (No ). Prof. Mo s man research neress nclude he heory and he mehod of hydropower enery and s analyss, elecrcy mare and opmzaon sraees Inernaonal Journal of Elecrcal Enery 150