Power Ancillary Service Option - Coupling Optimization of the High Back-pressure Unit and Cogeneration Unit

Presently the high back-pressure cogeneration unit utilizing the condensing heat as the heating source, has high power output under high heating load and poor peaking load performance. The coupling optimization of the high back-pressure unit and cogeneration unit is proposed as one option for improving the peaking load performance of power plant in power market. Coupling operation of the two units are optimized and analyzed based on established models of 350MW cogeneration unit with heating steam extraction and high back-pressure cogeneration unit using Ebsilon software, and special attention is paid to the change of peak load regulation performance and total economic benefit of the two units. Two scenarios are analyzed for the two example cogeneration units during night period. The calculation results show that compared with Scenario I the total peak load regulation depth can be increased by 38.77 MW while the total heating load remains unchanged at 600 MW in Scenario II, and the average total loading rate of the two units can be decreased from 54.2% to 48.7%, which means 5.5% deeper peaking load improvement using the proposed technique. Taking all revenues and costs into consideration, the total economic benefit of the two units will be decreased by 1.03×10
⁴
Yuan/h by application of the proposed technique in Scenario II, which is corresponding to 0.2657 Yuan/kWh compensation standard or compensation cost for the proposed technique. Since adoption of the proposed technique doesn’t involve any technical upgrading of the existing units and extra investment, the expected performance improvement will reduce the uncertainty of future application prospect for the proposed technique.