The concept of 6MW extraction steam turbine is that the power generation capacity can reach 6MW rated cogeneration unit (1, pure condensing condition, full load of 6MW, that is, it does not provide hot steam to systems other than the thermal system of the power plant. 2. Under the condition of air extraction, it can also generate 6MW. At the same time, a certain stage of steam turbine extracts steam to supply steam to the external network. In fact, it is the steam turbine that realizes the off-design operation. One is that all the incoming steam is used to generate electricity, and the other is that part of the steam is used to generate electricity, and part of it is pumped out for the heat of the external network after doing some work in the cylinder.