Abstract: With the change of domestic power consumption structure, large-scale thermal power units should participate in the peak regulation according to the requirements. In this paper,taking the 660 MW unit as the object, according to the coal consumption results of the performance test, the two operation mode of the economic situation including low-load operation and two-shift system mode under the depth peak shaving operation is compared.If the load capacity of the power plant is larger and the peak-shaving time is longer, the economy of the start-stop double shift system is more remarkable. For subcritical peaking units, the economic mode of low load operation is always better than that of two shift system. However, if the peak regulation time is longer, especially the deep peak regulation is not limited to the hot start time, the two shift system operation mode will has more energy-saving significance.

Key words: depth peak shaving, low load, two shifts, economy