外文翻譯--小型網(wǎng)絡互聯(lián)風力發(fā)電機功率器件可靠性分析（英文）

1、Reliability analysis of grid connected small wind turbine power electronicsMd. Arifujjaman *, M.T. Iqbal, J.E. QuaicoeFaculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL, Canad

2、a A1B3X5a r t i c l e i n f oArticle history:Received 30 June 2008Received in revised form 13 November 2008Accepted 10 January 2009Available online 11 February 2009Keywords:Renewable energyWind energyPower electronicsGri

3、d-tie inverterPermanent magnet generatorSmall wind turbinesSwitching lossesReliabilityMean time between failuresa b s t r a c tGrid connection of small permanent magnet generator (PMG) based wind turbines requires a powe

4、r con-ditioning system comprising a bridge rectifier, a dc–dc converter and a grid-tie inverter. This work pre-sents a reliability analysis and an identification of the least reliable component of the power conditionings

5、ystem of such grid connection arrangements. Reliability of the configuration is analyzed for the worstcase scenario of maximum conversion losses at a particular wind speed. The analysis reveals that the reli-ability of t

6、he power conditioning system of such PMG based wind turbines is fairly low and it reduces to84% of initial value within one year. The investigation is further enhanced by identifying the least reliablecomponent within th

7、e power conditioning system and found that the inverter has the dominant effect onthe system reliability, while the dc–dc converter has the least significant effect. The reliability analysisdemonstrates that a permanent

8、magnet generator based wind energy conversion system is not the bestoption from the point of view of power conditioning system reliability. The analysis also reveals that newresearch is required to determine a robust pow

9、er electronics configuration for small wind turbine conver-sion systems.? 2009 Elsevier Ltd. All rights reserved.1. IntroductionSmall wind energy conversion systems (WECSs) have evolved rapidly along with the large WECS

10、for generation of electricity in either on-grid or off-grid applications. WECS are considered as complex systems comprising mechanical subsystems (rotor, hub, and gearbox) and electrical subsystems (converter/inverter, r

11、ecti- fier, and control) and loads. Failures in any of the subsystems can cause substantial financial loss. The problem becomes more severe if the system is off-grid leading to unavailability of power. In light of this,

12、there is a need for reliability evaluation of small WECS in order to determine a configuration that is efficient and reliable. Almost all commercially available small wind turbines are based on PMGs. The power conditioni

13、ng systems (PCSs) for grid connection of the PMG based configuration requires a rectifier, boost converter, and a grid-tie inverter. The reliability analysis of such PCS is greatly influenced by the operating conditions,

14、 i.e., covariates and therefore it is desirable to investigate the magni- tude of their effects on the system reliability. Reliability calculation consider the voltage or current as a covariate for an electrome- chanical

15、 system [1], while the reliability of power electronic com- ponents is strongly influenced by the component temperature and variations [2]. Knowledge of the reliability of power electronic components is a key concern whe

16、n differentiating between topol-ogies. However, recent research intermittently endeavors to deter- mine the reliability and advancement of the inverter rather than the PCS [2–4]. Most of the reliability calculations are

17、based on the accessible data provided by the military handbook for reliabil- ity prediction of electronic equipment which is criticized for being obsolete and pessimistic [5,6]. A comparative reliability analysis of diff

18、erent converter systems has been carried out based on the mil- itary handbook by Aten et al. [6]; however, the absence of environ- mental and current stress factors can pose grim constraints on the calculated reliability

19、 value. Rohouma et al. [7] provided a reliability calculation for an entire PV unit which can be considered more useful, but the approach lacks valid justification as the data pro- vided by the author is taken from the m

20、anufacturers’ published data which is somewhat questionable. Indeed, accurate reliability data of the rectifier, converter, or inverter are helpful to determine the total PCS reliability; however, the calculated reliabil

21、ity could be uncertain once approaching to reliability calculation using purely statistical methods [8], from the manufacturers’ provided data [3,7] or using the military handbook data [9], which consider rectifier, conv

22、erter and inverter as a total system and neglect their operating point that could vary from one user to other. Moreover, the total number of components could vary for a same system in order to meet a certain criteria of

23、the overall system. Although higher components in the PCS will exhibit less reli- ability and vice versa, but the effects of the covariates could be dif- ferent and consequently leading to a variation in the reliability

24、[10]. Furthermore, a need of the reliability evaluation for the PCS0306-2619/$ - see front matter ? 2009 Elsevier Ltd. All rights reserved.doi:10.1016/j.apenergy.2009.01.009* Corresponding author. Tel.: +1 709 749 2357.E

25、-mail address: mda04@mun.ca (Md. Arifujjaman).Applied Energy 86 (2009) 1617–1623Contents lists available at ScienceDirectApplied Energyjournal homepage: www.elsevier.com/locate/apenergy3. Failure modes of small wind turb

26、ine systemsThe need for long term field data is of great importance to the evaluation of technical and economical performances. Long term failure and reliability data for wind turbine subsystems are readily available bec

27、ause of the significant (and growing) number of wind turbines of various age, type and location in existence across the world. This information facilitates the identification of the most probable failure subsystems in WE

28、CS, and allows optimization of the design features as well as system configuration. A review has been conducted for the failure distribution of SWT subsystems. Data published by The Scientific Monitoring and Evaluation P

29、ro- gramme (WMEP) in Germany [16], Elsfork, Sweden [17], and Land- wirtschaftskammer, Schleswing-Holstein, Germany (LWK) [18] are presented in Fig. 2 along with the large wind turbine data provided by DOWEC project in Ne

30、therland [19]. In the review, mechanical subsystems consist of drive train, gears, mechanical brakes, hydraulics, yaw system hubs, and blade/pitch while, the generator, sensors, electric system, and control system compri

31、se the electrical subsystem. The distribution of the number of failure depicted in Fig. 2 shows that the sum of the failure rates of the electrical re- lated subsystems is higher in contrast to the mechanical subsys- tem

32、s. A completely reverse portrait exists for large wind turbines where the failure mode is principally dominated by the mechanical subsystems. Indeed, the electric and control system composed of power electronic component

33、s is an integral part of any PCS which not only dictates the performance but also bear a major fraction of the overall cost for a small WECS. As a whole, in order to ensure high reliability, attention should be focused o

34、n small WECS with straightforward but reliable PCS design that ensure easy mainte- nance and repair as well as less complexity in the control architec- ture for an optimum life.4. Mathematical analysisA mathematical anal

35、ysis of the power losses in the power elec- tronics components, i.e., semiconductors (diodes/IGBTs) is required in order to complete a reliability analysis of the configuration. The losses for the power conditioning syst

36、ems are strongly dependent on the voltage and current waveforms. Simplified analytical deri- vation of voltage and current equations associated with the indi- vidual semiconductor components are derived to determine the

37、losses. The loss calculation presented in this investigation focus on the losses generated during the conduction and switching states of the semiconductors. Afterwards, the mathematical analysis for reliability of the sy

38、stem is presented.4.1. Loss analysis for a PMG based SWTFor the 3-phase diode bridge rectifier, the losses are calculated for a single diode from the known voltage and current equations. It is assumed that the current an

39、d voltage in the 3-phase diode bridge rectifier are equally distributed in the diodes. Knowing the voltage and current for one diode, the losses can be obtained for all the diodes in the bridge rectifier. The conduction

40、losses, PDB cd;d for the diode is expressed asPDB cd;d ¼ Vf0Id ð1ÞUnder the assumption of a linear loss model for the diodes, the switching loss in each diode is given by [20]PDB sw;d ¼ fWTESR ? Vdc1

41、Vref;d ? Idc1 Iref;d ð2ÞThe total losses of the 3-phase diode bridge rectifier, PDB t;d for all 6 diodes is given byPDB t;d ¼ 6PDB cd;d þ 6PDB sw;d ¼ PDB cdt;d þ PDB swt;DB ð3ÞThe

42、conduction and switching loss of the Boost Converter (BC) is calculated by assuming an ideal inductor (LD) at the boost con- verter input. For a boost configuration, the IGBT is turned on for the duration d while the dio

43、de (D) conducts for the duration (1?d). The conduction current of the IGBT is the input current Idc1 while the inverter input current Idc2 is given byIdc2 ¼ Idc1ð1 ? dÞ ð4ÞThe conduction loss for

44、 the diode and IGBT can be obtained by multiplying their on-state voltage and current with the respective duty cycle and is given by [21]PBC cd;d ¼ Idc1ðVf0 þ rdIdc1Þ ? ð1 ? dÞ ð5Þ

45、PBC cd;IGBT ¼ Idc1ðVce0 þ rceIdc1Þ ? d ð6ÞThe commutation voltage and current for the boost converter is the DC link voltage, Vdc2 and input current to the converter, Idc1. The switching los

46、ses for a specific switching frequency, fSW of the diode and IGBT in the BC are given by [21]PBC sw;d ¼ fswESR ? Vdc2 Vref;d : Idc1 Iref;d ð7ÞPBC sw;IGBT ¼ fswðEON þ EOFFÞ ? Vdc2 Vref;I

47、GBT ? Idc1 Iref;IGBT ð8ÞThe sum of (5)–(8) gives the losses of the BC asPBC t;ðdþIGBTÞ ¼ PBC cd;d þ PBC sw;d? ? þ PBC cd;IGBT þ PBC sw;IGBT? ? ð9ÞMost of the SWT sys

48、tems integrate a single phase inverter for industrial as well as residential application. With the exclusion of snubber circuit, the inverter consists of four switches and four anti parallel diodes as presented in Fig. 1

49、. The conduction losses of a diode and IGBT for the inverter can be expressed as [22],PINV cd1;d ¼ 18 ? M3p cos h? ?rdI2 om þ 12 þ M8 cos h? ?Vf0Iom ð10ÞPINV cd1;IGBT ¼ 18 þ M3p cos h?

50、?rceI2 om þ 12 þ M8 cos h? ?Vce0Iom ð11ÞAn approximated solution for the diode and IGBT switching losses at an output current io is given by [21]PINV sw1;IGBT ¼ 1 p fsw½EON þ EOFF? Vdc2

51、 Vref;IGBTIo Iref ;IGBT ð12ÞPINV sw1;d ¼ 1 p fswESRVdc2 Vref;dIo Iref ;d ð13ÞFig. 2. Distribution of the number of failures of small wind turbine subsystems.Md. Arifujjaman et al. / Applied Energ