AHP and Value Engineering Application in Electrical Equipment Procurement Hong-qing ZHANG

Transcription

1 nd Internatonal Conference on Socal Educaton and Management Engneerng (SEME 2016) ISBN: AHP and Value Engneerng Applcaton n Electrcal Equpment Procurement Hong-qng ZHANG School of Economcs and Management North Chna Electrc Power Unversty Beng Chna Keywords: AHP Value engneerng Functonal evaluaton ndex Electrcal equpment. Abstract. By analyzng the features of electrcal equpment the functonal evaluaton of electrcal equpment s establshed based on relablty effcency mantanablty and securty. Accordng to respectve functon of electrcal equpment the frst-class ndex s subdvded and then the functonal evaluaton ndex s bult. Functon coeffcents are calculated by AHP and the cost coeffcents are calculated by the whole lfe-cycle theory. The optmal soluton s selected based on the prncples of value engneerng. Ths paper uses transformer as an example to llustrate the feasblty of ths method. Introducton Wth our country s rapd ndustral development the demand of electrcty s ncreasng. Falure of electrcal equpment wll brng the ndustry serous economc losses so the requrement of the electrcal equpment s more and more strct. The purchase prces of electrcal equpment are often expensve. How to meet the functonal needs and meet mnmum procurement costs at the tme of purchasng s the key research problem of electrcal equpment procurement. About ths ssue there are some researches. Ma Yngbn proposes Value Engneerng can not only meet the functonal needs but also reduce costs [1]. Marzouk M.M. proposes value engneerng can dentfy and reduce unnecessary costs [2]. The premse of usng value engneerng s determnng the functonal ndex. Sun Shmng establshes evaluaton ndex system of electrcal equpment fully reflected the needs of the procurement [3]. Zhao Hu and Wang Shuyan propose evaluaton ndex of electrcal equpment procurement tender and usng the AHP to determne the rght weght [4]. Transformer s the core element of electrcal equpment. For ts man ndcators of qualty Ln Gu analyzes the reasons of abnormal falure of sound ol level and ol temperature [5]. Wang Png analyzes the data and cause combned wth falure condtons of man transformer [6]. Tang Xaofe analyzes the man qualty defects of electrcal transformers and studed the key factors that nfluence these defects [7]. Xu Nng notes several key techncal ssues of transformer procurement [8]. Usng value Engneerng also need the cost factors of electrcal equpment. Lu Huayong Xe Kagu and Luo Xaochu propose fee structure and calculaton model of lfe cycle cost of electrcal equpment [9]. Cao Yang ntroduces the entre lfe cycle theory nto the comprehensve assessment model of electrcal equpment [10].Yn Ke apples LCC management to the bddng of transformer [11]. Yang Chunhao ntroduces the man cost factors of the transformer s LCC [12]. Zhong Sheng explores the cost components of transformer [13].The above studes nvolve the determnaton of functonal parameter and cost factor but they neffectvely combned the unque features of electrcal equpment. Ths paper uses AHP combnng value engneerng focusng on analyzng functonal ndex system of electrcal equpment to provde scentfc and effectve method for the selecton of hgh-qualty electrcal equpment. Prncple Value engneerng s also known as value analyss process. V (value) = F (functon) / C (cost). It focuses on analyzng functons of some parts of the product or proect. It s desrable to get the requred functon user needs wth the lowest cost. Analytc Herarchy Process (AHP) s a mult-obectve decson analyss method combnng qualtatve and quanttatve analyss. Specfc

2 steps of ths method s to classfy the ssues nvolved frstly then consttute a herarchy dagram and determne relatve mportance weght of each layer factors. When calculatng functonal coeffcent t often use expert scorng method. Experts determne mportance of factors wth ther experences. People can t be completely consstent udgment to varous factors of complex matters whch may lead to bas of functon coeffcents. To mnmze ths devaton ths artcle calculates functon coeffcents wth AHP and then selects the best product based on value engneerng prncple. Determnng Functon Coeffcents For the optmal choce of electrcal equpment t frstly needs to determne the functonal specfcatons of electrcal equpment whch manly dvded nto relablty effcency mantanablty and securty. Relablty refers to the possblty of qualty problems durng the operaton of electrcal equpment. Effcency s the degree of satsfyng the performance parameters. Mantanablty manly refers to the ablty of mantanng or restorng to a predetermned state durng routne mantenance and repar. Securty manly refers to degree of safety assurance durng the operaton of electrcal equpment. Ths paper takes transformer as an example. It establshes functonal ndex system based on the analyss of transformer s functon. Table 1 s a subdvson of the four frst-class functon ndexes. Index layer1 relabltyb 1 effcencyb 2 mantanabltyb 3 securtyb 4 Table 1. Transformer functon ndex system. Index layer2 ImpervousnessC 11 Short-crcut wthstand ablty C 12 One-Pont groundng relabltyc 13 Heat-resstant grade of nsulatng materalc 14 No-load electrctyc 21 No-Load LossC 22 Load lossc 23 Impedance voltage C 24 Servce lfec 25 After sales servcec 31 Ease of mantenancec 32 Components versatltyc 33 Tghtness of termnalsc 41 Reasonable of protecton untc 42 The common problems of transformer are ol leakage short crcut multpont groundng and local overheatng. Impervousness s related wth Fuel tank weldng and Total Assembly. Ablty to wthstand short crcut s related to nsulatng parts manufacturng col Assembly and body pressng. Manufacturers poor desgn short dstance of nternal nsulaton and metal weldng ballast exsted nner ol wll cause multple-pont groundng malfuncton. Hgh temperature s correlated to resstant rank of nsulatng materal. The greater No-load electrcty becomes the easer wndng fever. But the No-load electrcty can t be too small n order to avod affectng other performances of the motor. No-Load loss and load loss as small as possble. It s related to slcon grades burr sze the seam pattern and lamnaton technology. Impedance voltage should closer to the natonal standard. Transformer protecton devces generally nclude pressure relef valve temperature measurement devce gas relay and surge arrester. Functonal ndex coeffcents are calculated by AHP. Use expert scorng method to calculate each ndex score β ( represents the -th program represents the -th functon ndex). Then calculate functon scores β and functon coeffcents F of the programs by the formula (1) and the formula (2).

3 β n = ω β =1 (1) β F = n = 1 β Table 2. Index layer 1 functonal mportance results. Total functon Relablty effcency mantanablty securty Relablty 1 1/3 3 1 effcency mantanablty 1/3 1/5 1 1/3 securty 1 1/3 3 1 Result: ω = ( ) 04 λ n CI = = CR = = n B1-C: ω = ( ) CI=0.0103CR= B2-C: ω = ( ) CI=0.0033CR= B3-C: ω = ( ) CI=0.037CR=0.063 B4-C: ω = ( ) CI=0CR=0 All udgment matrxes are consstent. The weghts of ndex layer 2 can be calculated by the weghts of ndex layer 1 and B -C. Then three transformers X Y Z can be scored ndex layer 2. Table 3. Index layer 2 functonal ndex weghts. C 11 C 12 C 13 C 14 C 21 C 22 C C 24 C 25 C 31 C 32 C 33 C 41 C Table 4. Transformers scores C 11 C 12 C 13 C 14 C 21 C 22 C 23 C 24 C 25 C 31 C 32 C 33 C 41 C 42 X Y Z Accordng to the formula (1) functon scores of each transformer are: and Accordng to the formula (2) functon coeffcents of each transformer are: and (2) Determnng Cost Factors Lfe cycle cost of electrcal equpment (LCC) ncludes the fee of purchasng nstallaton operaton mantenance renovaton and scrap. It nclude CI (ntal nvestment cost) CO (energy costs operaton mantenance overhaul and Pretest costs) CF (falure costs) CD (retred and dsposal costs). Ths paper takes transformer as an example. CI ncludes purchase costs of equpment nstallaton commssonng cost and other expenses. The costs of operaton mantenance repar and pre-tral account for about 10% of ntal nvestment cost. Energy costs account for about 5% of ntal nvestment cost. The transformer s resdual value s hgh and wll get a proft recovery n the decommssonng process. It account for about 3% of the purchase cost. Accordng to the formula (3) (4) (5) calculate transformer s lfe cycle costs cost coeffcents and value coeffcents.

4 LCC = CI + CO + CF + CD (3) C = n = LCC LCC 1 (4) F V = C (5) Transformer X: Quote 40 mllon mantenance-free overhaul s not requred durng normal operaton. Transformer Y: Quote 35 mllon. Three maor repars are needed n the lfe cycle of 30 years whch respectvely are 5 years 15 and 25 years. One maor overhaul cost s 4.02 mllon dscounted present values. Transformer Z: Quote 38 mllon. Two maor repars are needed n the lfe cycle of 30 years whch respectvely are 10 and 20 years. One maor overhaul cost s 4.02 mllon dscounted present values. Accordng to the formula (3) transformer s LCC are mllon. Accordng to the formula (4) transformer s cost coeffcents are and Accordng to the formula (5) value coeffcents of each transformer are and By comparng value coeffcents of three transformers the larger value coeffcents s the greater the transformer s so transformer X should be selected as the optmal decson. Summares Ths artcle focuses on analyzng features of electrcal equpment and establshes the functonal evaluaton ndex of electrcal equpment. It proposes that functonal evaluaton ndex should be establshed based on relablty effcency mantanablty and securty. It takes transformer as an example focusng on analyzng functonal ndexes and subdvdes the frst-class ndex. Functon coeffcents are calculated by AHP. Use value engneerng theory n electrcal equpment procurement to select the case wth the hghest value coeffcents as the optmal soluton. The example nvolved n paper proves that ths method s helpful for actual electrcal equpment purchasng. References [1] Ma Yngbn Yu You B Mngzh Optmzaton research of procurement tender based on value engneerng J. Value Engneerng. 04(2015)2-3. [2] Marzouk M.M Electre III model for value engneerng applcatons J. Automaton n Constructon. 5(2011) [3] Sun Shmng Applcaton research of value engneerng n electrcal equpment s procurement tender D. the North Chna Electrc Power Unversty [4] Zhao Hu Wang Shuyan Applcaton of AHP n electrcal Equpment Bddng J. Small Hydro Power. 01(2010) [5] Ln Gu The explorng research for safe operaton of electrcal transformer J. Practcal Electroncs. 08(2015) 210. [6] Wang Png Wang Xngu Ma Yuln The Analyss of 35kV man Transformer s malfuncton J. rural electrfcaton. 02(2015)34-35.

5 [7] Tang Xaofe The research of transformer manufacturng s qualty control D. Nanng Unversty of Scence and Technology [8] Xu nng Several key technologcal problems of new 500kV transformer J. Jangsu Electrcal Engneerng. 03 (2005) [9] Lu Huayong Xe Kagu Luo Xaochu The relable management of electrcal equpment s lfe cycle cost J. Gong dan yong. 03(2010)8-11. [10] Cao Yang Electrcal equpment Procurement Evaluaton Method and Its Applcaton Based on LCC theory D. Chongqng Unversty [11] Yn Ke Yu Dongsheng L Lhua etc Research and Applcaton of LCC method for evaluatng 500kV transformer J. East Chna Electrc Power (11). [12] Yang Chunhao Transformer bddng based on full lfe-cycle costs J.Yunnan Electrc Power Technology (03). [13] Zhong Sheng Yu Xaofeng Wu Haquan etc 220kV transformer cost s senstvty and cost estmaton model J. Guangdong Electrc Power (06).