Peak Load Regulating Capability and Economic Benefit Analysis of Existing Cogeneration Unit for Power Grid Resilience

Abstract

With the increasingly higher penetration of renewable energy into the power grid and increasing pressure of the enhancing the peak load regulating capability of the cogeneration units, it's critical that peak load regulating capability of the existing cogeneration units be evaluated accurately. Model-based software code is used for the performance simulation of one 300MW subcritical cogeneration unit, and detailed information is provided concerning specific details involved in the modeling process. Unit performance especially the unit load regulating capability under various heating load conditions is studied. It is shown from the calculation result under 75% heating load condition, when the main steam inlet flow is decreased and the LP turbine inlet flow reaches its minimum cooling flow setting limit, the unit minimum power output of 152.77MW is achieved which is nearly 50% of the unit rated output. It also suggest that for 75% or higher heating load conditions, with the increasing of the heating load the unit minimum power output is increased rapidly and the peak load regulating range is contracted drastically. For heating load conditions lower than 75%, the peak load regulating capability of the existing cogeneration unit can meet the minimum load requirement of the state regulation. It is suggested that for cogeneration unit frequently operating with 75% or more heating load in heating season, flexibility upgrading measures should be taken to decrease the minimum power output, while it's better to decrease the minimum power output of the unit via operation measures for unit frequently operating with less 75% heating load.