小型自然循环蒸汽发生器水位控制特性分析

Water level control characteristic analysis for the small natural circulation steam generator

针对小型立式自然循环U形管蒸汽发生器,提出基于经典PID控制理论模型的二回路侧水位控制方块图和数学模型,并采用RELAP5程序建立含水位控制的蒸汽发生器热工水力瞬态分析模型,研究了10%FP阶跃降升负荷、大幅度阶跃降升负荷2种情况下蒸汽发生器的热工水力动态特性,分析了水位控制方案的可行性。结果表明,所设计的水位控制系统以及PID整定参数取值基本满足功率运行控制需求,但由于影响两相流水位因素的多参数复杂性,使得某些负荷下水位控制系统带有一定的非线性特征,在工程上标定水位和给水流量时需要重点关注。

The classical PID control theory model of secondary side water level control block diagram and mathematics model are proposed,to research a small vertical natural circulation steam generator.The thermal-hydraulic transient analysis model including the water level control model is simulated using the RELA5 code.And the steam generator thermal-hydraulic dynamic characteristics of the two load change cases at the 10%FP load step time and largely load step time are studied.The feasibility of water level control strategy is also analyzed.The results show that,the designed water level control system and PID setpoint parameters can satisfy basic power operation control requirements.The nonlinear characteristic of water level control system is evident at certain load as it is influenced by many thermal parameter factors during the twophase flow dynamic process.It should be carefully done the water level and feedwater mass flow calibration in the practical engineering.