Operation Flexibility Analysis of Combined Heat and Power Plant Using High and Low Bypass

China's energy structure is currently in the transition stage, in order to absorb large-scale new energy into the network, it is necessary to improve the flexibility of cogeneration units, high and low bypass heating technology is an excellent flexibility transformation technology, can effectively improve the peak load capacity and heating capacity of heating units. Based on a 2×350 MW supercritical unit in North China, this paper uses EBSILON modeling and simulation software to build thermodynamic models of the unit's pure condensate condition, IP cylinder exhaust steam extraction heating mode and high and low bypass heating mode. The reliability of the models is demonstrated by comparing with the designed values. According to the boundary conditions of variable operating conditions of the unit, the calculation results of the whole operating range of the model show that the thermo- electric decoupling ability of the unit is improved by the high-low pressure bypass heating mode. Compared with the IP exhaust steam extraction heating mode, the maximum heat load is increased by 41.6%, and the minimum electric load after heating is reduced by 13.2%. The heat economy of the high and low bypass heating system is relatively poor, and the heat consumption of power generation is increased by 14%-47% compared with that of the IP exhaust steam extraction heating system. The unit with high and low bypass heating operation has a larger thermoelectric load operation range, and under the same heating load, the high and low bypass heating unit has a larger electric load peak loading range, so that the unit has a better flexible operation capacity, which has a positive reference value for the implementation of the flexibility transformation of the heating unit.