燃气-蒸汽联合循环机组灵活性供热控制策略

Flexible heating control strategy for gas-steam combined cycle unit

燃气-蒸汽联合循环热电机组在冬季气源紧张情况下会出现机组供热出力不足,严重影响供暖质量。为此,本文对燃气-蒸汽联合循环机组进行节气保供热灵活性供热技术研究,设计了适应不同天然气量和供热负荷的6种供热模式,分别为高背压供热模式、抽汽高背压供热模式、低压缸空载供热模式、单台余热锅炉耦合高背压供热模式、单台余热锅炉耦合空载供热模式和2台余热锅炉供热模式。同时研发了全供热工况控制策略,主要包括供热模式切换控制策略及供热在线优化策略。对山西某燃气-蒸汽联合循环机组进行6种供热模式控制策略工程试验,结果表明,该灵活性供热控制策略能够实时准确地根据系统状态自动选择模式切换或运行参数优化,使供热负荷与供热需求间误差不超过1%。某860 MW燃气-蒸汽联合热电机组在300万m3/d的定气量条件下,每日最高可供热量5.2万GJ,热调峰能力提高约45%,机组灵活供热调峰能力明显提高。

Natural gas shortage in winter will cause insufficient heating output of gas-steam combined cycle thermal power generation units,which seriously affects the heating quality.For this reason,this article researches the flexible heating technology of a gas-steam combined cycle unit.Six heating modes are designed for conditions with different natural gas volumes and heating loads,namely high back pressure heating mode,high back pressure heating mode with extraction steam,low-pressure cylinder no-load operation mode for heating,single waste heat boiler coupling with high back pressure heating mode,single waste heat boiler coupling with no-load operation heating mode,and double waste heat boiler heating mode.Moreover,a control strategy is developed for all heating conditions,which mainly includes heating mode switching strategies and heating online optimization strategies.Furthermore,engineering test of the control strategy under six heating modes was carried out on a gas-steam combined cycle unit in Shanxi,and the results show that,the flexible heating control strategy can automatically select mode switching or operation parameter optimization according to the system state in real time and accurately,so that the error between heating load and heating demand can be controlled below 1%.The unit can provide 52000 GJ heat per day at a fixed natural gas volume of 3 million m3/d,namely the thermal peak regulation capacity of the unit increased by about 45%,indicating the capacity of the unit in flexible heat supply and peak load regulation is dramatically improued.