Cheng-Ting Hsu Presenter: Cheng-Ting Hsu Cogeneration System Design for a High-Tech Science-Based Industrial Park Department of Electrical Engineering Southern Taiwan University of Technology Tainan, Taiwan

˙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 Outline

Introduction With so many semiconductor manufacturers in the science- based 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 (MW) Total Gen. (MW) Total Load (MW) 3G1S G1S45 OFF G1S 45OFF

Short Circuit Analysis The Short Circuit Current at Long-Song Substation Cases Total fault current (kA) Fault current supplied by cogeneration (kA) with 161/161 kV transformers I" k I asym I peak IbIb without 161/161 kV transformers I" k I asym I peak IbIb

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 27 relay: 0.65pu 81L relay: 58.4 Hz with 0.1second time delay

Load Shedding Scheme where m 0 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 H1H2 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

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. Conclusions