大型汽輪發電機組由於其結構及轉速等需求，汽輪機振模較難遠離電力系統兩倍頻，因此低壓汽機末級葉片受電力系統不平衡引發的振盪轉矩影響很大，嚴重者如核三廠於1985年7月葉片斷裂事故，但大多數情形下其作用是潛在且長期的，在運轉數年或數十年才累積至損壞程度。換言之，電力系統不平衡對葉片短期運轉損傷可被忽略，但對長期運轉可靠度而言確有其重要的影響。
台電或國外許多機組有運轉數年後，在無重大事故的情況下發生葉片龜裂事件，其形成原因大部分屬應力腐蝕龜裂 (S.C.C.)與腐蝕疲勞 (C.F.)兩種。本論文即針對腐蝕疲勞加以探討，在NaCl環境與穩態不平衡振盪轉矩的同時作用下，研究葉片之疲勞壽命機率並分析其在設計年限下之可靠度。
當汽輪機在NaCl腐蝕性環境下運轉時，葉片很容易產生腐蝕疲勞的現象，因此，即使是小應力也同樣的會損及葉片。本研究以GAMMA分佈之不平衡電流探討汽輪發電機系統之葉片疲勞壽命、可靠度及裂縫成長，其中考慮不同的葉片材質、安全因數和應力集中因數等；同時，我們也研究負相序電流 (I2 )最大值分佈對葉片可靠度的影響。

Usually, a large steam turbine-generator unit has itself a blade vibration mode that is close to its double electrical frequency. This mode of vibration will easily be excited by electrical load unbalance, thereby the turbine blades will be affected by this kind of vibrations, especially for the last three rows of blades. In fact, turbine generators operate in corrosive environment and undergo the statistical stress impact due to the randomly unbalanced currents. In this paper, the blades are subjected to corrosion fatigue, thereby small stress still may cause damage significantly. On the other hand, the damage caused by system unbalance is so small that people could neglect it usually. Nevertheless, for the long-term operation with lasting system unbalance, its influence on reliability may no longer be omitted.
According to the gamma distribution in unbalanced negative phase current (I2), the probability level of fatigue life, the reliability against fatigue failure and crack growth of turbine blades are evaluated for three turbine-generator system in the paper. The blades with various materials, safety factors and stress concentration factors are considered in the simulations. The influence of extreme value distribution of I2 to the reliability is also investigated. According to the results, we have reason to believe that corrosion fatigue is one of causes that led to crack initiation or damage of blades under normal operation.

摘要………………………………………………………………
ABSTRACT….. ………………………………………………..
目錄………………………………………………………………
圖目錄……………………………………………………………
表目錄……………………………………………………………
第一章 緒論1.1 研究背景…………………………………………………
.1.2 影響汽機葉片振動的原因………………………………..
1.3 電力系統不平衡………………………………………….
.1.4 電力系統不平衡對發電機的影響……………………….
1.5 電力系統不平衡引發之兩倍頻電磁轉矩………………
第二章 汽輪發電機系統介紹2-1 前言………………………………………………………
2-2 系統架構…………………………………………………
2-3 系統模型建立……………………………………………
2-2-1 機械系統模型…………………………………….
2-2-2 同步機模型……………………………………….
2-3-3 控制系統模型…………………………………….
第三章 汽輪發電機的系統響應
3.1 前言………………………………………………………
3.2 影響汽機葉片的因素
-2-1 汽機的操作環境…………………………………
3-2-2 汽機的葉片材料…………………………………
3-2-3 葉片材質的腐蝕疲勞特性………………………
3.3 葉片振模分析…….………………………………………
3.4 葉片動態響應時域分析………………………….………
第四章 疲勞壽命損耗理論
4.1 疲勞壽命損耗估算理論…………………………………
4.2 腐蝕疲勞…………………………………………………
4.3 疲勞壽命可靠度理論……………………………………
4.4破壞探討…..…………………………………………….
第五章 疲勞壽命,可靠度與裂縫成長之模擬結果
5.1前言………………………………..…………………….
5.2 疲勞壽命模擬結果
5.2.1 951MW機組……………………………………..
5.2.2 660MW機組……………………………………..
5.2.3 1300MW機組……………………………………..
5.3 可靠度模擬結果5.3.1 951MW機組……………………………………..
5.3.2 660MW機組……………………………………..
5.3.3 1300MW機組……………………………………..
5.4 裂縫成長的模擬結果……………………………………
第六章 結論……………………………………………………..
參考文獻………………………………………………………….
附錄……………………………………………………………….

[1] 王聰榮,"汽輪發電機扭轉震動問題之探討",台電工程月刊,Vol.480,pp.58-61,1988.
[2] IEEE Committee Report, "A Bibiographies for Study of Subsynchronous Resonance between Rotation Machines and Power Systems,"IEEE Trans on PAS, Vol.PAS-95,JAN/BEB,PP.216-218,1976.
[3] T. J. Hammons, "Stressing of large turbine-generators at shaft couplings and LP turbine final-stage blade roots following clearance of grid system faults and faulty synchronisation," IEEE Trans. on Power Apparatus and System, PAS-99, No. 4, pp. 1652-1662, 1980.
[4] A. J. Gonzalez, G. C. Kung, C. Raczkowski, C. W. Taylor and D. Thonn, "Effects of single- and three-pole switching and high-speed reclosing on turbo-generator shafts and blades," IEEE Trans. on Power Apparatus and System, PAS-103, No. 11, pp. 3218-3228, 1984.
[5] C. J. Cudworth and J. R. Smith, "Steam turbine generator shaft torque transients: A comparison of simulated and test results," IEE Proc., Pt. C, Vo1. 137, No. 5, pp. 327-334, 1990.
[6] M. A. Masrur, A. K. Ayoub and J. T. Tielking, "Studies on asynchronous operation of synchronous machines and related shaft torsional stresses," IEE Proc., Pt. C, Vo1. 138, No. l, pp. 4756, 1991.
[7] S. O. Faried, R. Billinton, S. Aboreshaid and M. Fotuhi-Fifilzabad, "Stochastic evaluation of turbine-generator shaft torsional torques during faulty synchronisation," IEE Proc. - Generation. Transmission. and Distribution, Vo1. 143, No. 5, pp. 487-491, 1996.
[8] N. Aspragathos, and A. D. Dimaroganas, "Fatigue damage of turbine-generator shafts due to fast re-closing," IEE Proc., Vol. 129, Pt. C, No1, pp. 1-9, 1982.
[9] I. M. Canay, H. J. Rohrer, and K. E. Schnirel, "Effect of electrical disturbances, grid recovery voltage and generator inertia on maximization of mechanical torques in large turbo-generator sets," IEEE Trans. on Power Apparatus and Systems, vol. PAS-99, No. 4, pp. 1357-1370, 1980.
[10] A. Abolins, D. Lambrecht, J. S. Joyce, and L. T. Rosenberg, "Effect of clearing short circuits and automatic re-closing on torsional stress and life expenditure of turbine-generator shafts," IEEE Trans. on Power Apparatus and Systems, vol. PAS-95, No. 2, pp. 461-468, 1976.
[11] J. S. Joyce, T. Kulig, and D. Lambrecht, "Torsional fatigue of turbine-generator shafts caused by different electrical power system," IEEE Trans. on Power Apparatus and Systems, PAS-97, No. 5, pp. 1965-1877, 1978.
[12] IEEE Working Group of the Synchronous Machinery Subcommittee, "Effects of switching network disturbances on turbine-generator shaft systems," IEEE Trans. on Power Apparatus and Systems, PAS-101, No. 9, pp. 3151-3157, 1982.
[13] R. G. Cheetham, and P. A. Walker, "Coordinated self-tuning control for turbine and exciter of a turbo-alternator," Electric Machines and Power Systems, No. 15, pp. 177-198, 1988.
[14] B. L. Agrawal, and R. G. Faramer, "Effective damping for SSR analysis of parallel turbine-generators," IEEE Trans. on Power Systems, vol.3, No. 4, pp. 1441-1448, 1988.
[15] IEEE SSR Working Group, "Countermeasures to sub-synchronous resonance problem," IEEE Trans. on Power Systems, PAS-99, No. 5, pp. 1810-1818, 1980.
[16] O. Wasynczuk, "Damping shaft torsional oscillations with application to high speed re-closure," IEEE Trans. on Power Systems, Vol.100, No. 3, pp. 1089-1095, 1981.
[17] O. Wasynczuk, "Damping sub-synchronous resonance using reactive power control," IEEE Trans. on Power Systems, vol.100, No. 3, pp. 1096-1104, 1981.
[18] N. G. Hingorani, "A new scheme for sub-synchronous resonance damping of torsional oscillations and transient torque-Part I," IEEE Trans. on Power Systems, Vol.100, No. 4, pp. 1852-1855, 1981.
[19] O. Wasynczuk, "Damping shaft torsional oscillations using a dynamically controlled resistor bank," IEEE Trans. on Power Systems, Vol.100, No. 7, pp. 3340-3349, 1981.
[20] D.J.N. Limeer, R. G. Harley and M. A. Lahoud, "Suppressing sub-synchronous resonance with static filters," IEE Proc., Vol. 128,Pt.C, No.1, pp. 33-44, 1981.
[21] A. E. Hammad, and M. El-Sadek, "Application of a thyristor controlled VAR compensator for damping sub-synchronous oscillations in power systems," IEEE Trans. on Power Systems, vol. 103, No. 1, pp. 198-212, 1984.
[22] B. T. Ooi, and G. Joos, "A passive shunt device to suppress torsional interactions in synchronous generators." IEEE Trans. on Energy Conversion, EC-1, No. 1, pp. 161-168, 1986.
[23] A. M El-Serafi, M. Y. Niamat, and E. Haq, " contribution of power system stabilizers to the damping of torsional oscillations of large turbo-generators." Electric Machines and Power Systems, No.11, pp.451-464, 1986.
[24] L. Wang, and Y. Y. hsu, "Damping of sub-synchronous resonance using excitation controllers and static VAR compensators: A comparative study," IEEE Trans. on Energy Conversion, EC-3, No.1, pp. 6-13, 1988.
[25] H. M. A. Hamdan and B. Kahhaleh, "Damping of power system oscillations by excitation control using a current feedback signal, " IEE Proc., Vol. 136, Pt. C, No.3, pp. 137-144, 1989.
[26] A. M. El-Serafi, and S. O. Faried, " Effect of field discharge resistors on turbine-generator shaft torsional torques," IEEE Trans. on Energy Conversion, EC-5, No.1, pp. 129-136, 1990.
[27] Y. S. Lee, and C. J. Wu, "Application of super-conducting magnetic energy storage unit on damping of turbo-generator sub-synchronous oscillation," IEE Proc., Pt. C, Vol.138, No.5, pp.419-426, 1991.
[28] T. P. Tsao, C. Chyn, and T. S. Tsai, "The effect of turbo-generator shaft couplings in depressing the vibrations caused by power system disturbance," Microcomputer Applications, Vol. 9, No. 2, pp. 66-71,1990.
[29] T. P. Tsao, and C. Chyn, "Analyze the torsional vibrations of turbine-generator shafts," Proc. of the 12-th symposium on electrical power engineering, Taipei, Taiwan, pp. 388-394, 1991.
[30] T. P. Tsao, and C. Chyn, "Restriction of turbine blade vibrations in turbo-generators," IEE Proc., Pt. C, Vol. 137, No. 5, pp. 339-342, 1990.
[31] 林翰榮,李金茂, "大型汽機的理論與實務,"台電核能月刊, pp.3-19, 1992.
[32] 王世仁, "迴轉機械振動問題解決之道,"台電工程月刊, Vol.511, pp.52-55,1991.
[33] 郭宗益,"電力系統同步研究中隻同步機模型導論(一)"台電工程月刊,Vol.460 ,pp.61-79,1986年12月.
[34] 郭宗益,"電力系統同步研究中隻同步機模型導論(二)"台電工程月刊,Vol.461 ,pp.77-93,1987年1月.
[35] O. I. Elgerd, Basic Electric Power Engineering, Addison-Wesley, Massachusetts, 1983.
[36] R. Bergen, Power System Analysis, Prentice-Hall, New York, 1986.
[37] IEEE Committee report, "Computer representation of excitation systems," IEEE Trans. on Power Apparatus and Systems, PAS-87, No. 6, pp. 1460-1464, 1968.
[38] D. C. Lee, R. E. Beaulieu, and G. J. Rogers, "Effects of governor characteristics on turbo-generator shaft torsionals," IEEE Trans. on Power Apparatus and Systems, PAS-104, No. 6, pp. 1255-1261, 1985.
[39] B. L. Agrawal, and R. G. Farmer, "Use of frequency scanning techniques for sub-synchronous resonance analysis," IEEE Trans. on Power Apparatus and Systems, PAS-98, pp. 341-349, 1979.
[40] M. El-Marsafawy, "Use of frequency-scan techniques for sub-synchronous-resonance analysis of a practical series-capacitor compensated AC network," IEE Proc., Vol. 130, Pt. C, No. 1, pp. 28-40, 1983.
[41] S. H. Smith and N. D. Ghadiali, "Fatigue crack growth life evaluation of the turbine blades in a low pressure steam turbine," Fracture Mechanics: Fourteenth Symposium - Volume II: Testing and Application, ASTM STP 791, pp. 120-139, 1983.
[42] Dewey R. P. and Rieger N. F., "Survey of steam turbine blade failures 1970-1981," EPRI CS-3891, March 1985.
[43] K. Walker, S. Pendleberry and R. Mcelwee, "Effects of environment and complex load history on fatigue life," ASTM STP 462, ASTM Philadelphia, p. 234, 1970.
[44] R.C. Bates, , J.W. Cunningham and R.I. Jaffee, "Corrosion of steam turbine blade materials in operational environment," EPRI CS-2932, September 1984.
[45] Jonas, O., "Characterization of steam turbine environment and selection of test environments," EPRI, Workshop on Corrosion Fatigue of Steam Turbine Blade Materials, Palo Alto, CA, September 1981.
[46] E. Cramer et al, "Fatigue assessment of ship structures," Det Norske Veritas Research, Report No. 94-2032.
[47] S. Gran, "A course in ocean engineering," Elsevier 1992. http://www.dnv.no/ocean/