Transcript 下載/瀏覽
Cogeneration System Design for a High-Tech Science-Based Industrial Park Cheng-Ting Hsu Presenter: Cheng-Ting Hsu Department of Electrical Engineering Southern Taiwan University of Technology Tainan, Taiwan Outline ˙Introduction ˙System Configurations of Cogeneration Facility ˙Short Circuit Analysis ˙Mathematical Modeling of Cogeneration Units ˙Protective Relay Setting for Tie Line ˙Load Shedding Scheme ˙Computer Simulation by Transient Stability Analysis ˙Conclusion Introduction • With so many semiconductor manufacturers in the sciencebased industrial park, power quality and service reliability have always been the critical issues for the industrial customers. • This paper presents the proper design of protective relay settings for tie line tripping and load shedding of a cogeneration system in a high-tech science-based industrial park. System Configurations of Cogeneration Facility Bus902 Bus903 Three Operation Modes of the Cogeneration System Operation Modes GTG1 (MW) GTG2 (MW) GTG3 (MW) STG Total Gen. (MW) (MW) Total Load (MW) 3G1S 45 45 45 26.9 161.9 151.9 2G1S 45 45 1G1S 45 OFF 26.9 116.9 151.9 OFF OFF 26.9 71.9 151.9 Short Circuit Analysis The Short Circuit Current at Long-Song Substation Cases with 161/161 kV transformers without 161/161 kV transformers I"k Iasym Ipeak Ib I"k Iasym Ipeak Ib Total fault current (kA) Fault current supplied by cogeneration (kA) 39.588 1.566 63.34 - 106.89 - 39.584 1.564 40.425 2.512 64.68 - 109.15 - 40.403 2.494 Mathematical Modeling of Cogeneration Units • Generator Model • Excitation System Model • Governor System Model Governor Model of Cogeneration Units Gas Turbine Steam Turbine Protective Relay Setting for Tie Line • 81L relay: 58.4 Hz with 0.1second time delay • 27 relay: 0.65pu Load Shedding Scheme Pstep 2H d 2H m0 0 dt 60 p.u. where m0 is the initial frequency decay rate at the tie line tripping H = 4.4pu for 3G1S = 3.36pu for 2G1S = 2.32pu for 1G1S Computer Simulation by Transient Stability Analysis • Case A: A three-phase bolted fault is assumed to occur at Long-Song substation and the relay 27 of the cogeneration system is activated to trip the tie line in 0.1 second after the fault. • Case B: A short circuit contingency with fault impedance of 6.22ohm occurs at Long-Song substation. • Case C: A far distance fault at TPC system is assumed and the relay 81L of the cogeneration is activated to trip the tie line. Case A A three-phase bolted fault is occurred at Long-Song substation and the under voltage relay of the cogeneration system is activated to trip CB H1 and H2 in 0.1 second. . F H1 H2 Bus 903 Bus 932 Bus 903 Bus 932 Case B A short circuit contingency with fault impedance occurs at Long-Song substation. The cogeneration is operated in 3G1S mode. Bus 903 Case C A far distance fault is assumed and the relay 81L of the cogeneration is activated at 58.4Hz to trip the tie line. The cogeneration system is operated in 3G1S, 2G1S and 1G1S modes. Gas turbine Steam turbine Conclusions • With the series 161/161 kV transformers, the short circuit current provided by the cogeneration system will be less than 2kA to meet the operational criterion. • With the series 161/161 kV transformers, the critical clearing time and the residual voltage at customer load buses can be both enhanced. • By applying the designed protective relay settings for tie line tripping and load shedding, the isolated cogeneration system will be restored to stable operation after transient disturbances introduced by utility faults.