1000 MW机组甩负荷瞬态过程分析及关键点控制

Transient Process Analysis and Key Point Control of 1000 MW Unit Load Rejection

针对二次再热机组甩负荷后,在维持转速稳定的过程中容易出现超高压缸和高压缸排汽温度超温现象,进而可能会出现切缸的问题,对甩负荷试验的必要条件、试验过程要点及试验数据进行梳理分析,详细阐述了甩负荷后出现超高压缸及高压缸排汽温度超限的控制方法,甩负荷后出现切缸及切缸后的重启控制,提出了三级旁路及其减温水配合甩负荷的控制方法。结果表明:甩负荷瞬态过程机组参数变化剧烈,数字式电液调节系统能快速响应,机组各调速汽门快速关闭,最高飞升转速及汽轮机转速动态超调量符合要求。使用三级旁路及其减温水配合甩负荷调整及严格执行试验规程的要求,可大大降低甩负荷瞬态过程的风险、提高机组运行的安全性。

After the load rejection of the secondary reheat unit,it is easy to cause the overheating of the exhaust steam temperature of the ultra-high pressure cylinder and the high pressure cylinder during the process of maintaining the speed stability,which may lead to the problem of cylinder cutting.The paper analyzes the logic judgment of the load rejection process,and comprehensively discusses the necessary conditions of the load rejection test,the key points of the load rejection test process,and the test data.The control method of the exhaust steam temperature of the ultra-high pressure cylinder and the high pressure cylinder after the load rejection is described in detail.The process of stopping steam intake and restarting the cylinder block after load rejection is also discussed.A control method of three-stage bypass and its cooling water with load rejection is proposed.The results show that the unit parameters change drastically during the load rejection transient,the digital electro-hydraulic control system control system can respond quickly,and the speed control valves of the unit close quickly.After the load rejection,the unit's maximum flying speed and the dynamic overshoot of the steam turbine meet the requirements.Through the adjustment of the above technical means and the strict implementation of the requirements of the test regulations,the risk of the transient load rejection process can be greatly reduced,and the safety of the unit operation can be improved.