A new control strategy for compensating degraded performance in gas turbine combined cycles

초록

The expansion of renewable energy has underscored the importance of improving efficiency during the part-load operation of gas turbine combined cycle (GTCC) plants. This paper proposes a new strategy to modify the temperature control curve (TCC) to compensate for the performance degradation of GTCCs resulting from longterm operation. A gas turbine model and TCC were developed using field data, and map-scaling was applied to simulate long-term compressor fouling and turbine erosion. A comparison was made between the existing method and the newly proposed TCC modification strategies under three degradation scenarios-compressor fouling, turbine erosion, and their combination. The proposed control strategy was found to be most effective when the turbine inlet temperature (TIT) was decreased continuously due to turbine erosion. In particular, when the TCC was modified to maintain a constant TIT, the GTCC power was compensated by up to 1.96 MW (0.73 %), and the efficiency was compensated by 0.33 percentage point. Moreover, even when compressor fouling also occurred, restoring the TIT compensated for the GTCC power and efficiency by 1.84 MW (0.69 %) and 0.36 percentage point, respectively. Consequently, the TCC modification strategy proved effective in mitigating the GTCC performance degradation without any hardware modifications.

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