As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect a...As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.展开更多
建立了考虑水电站引水系统水锤效应的弹性水体水轮机模型,并据此构建了水轮机调速系统模型。针对水轮机调速系统具有参数不确定性、存在干扰等特点,运用H∞鲁棒控制理论,提出了水轮机调速系统H∞双回路鲁棒控制策略,以水门开度偏差为补...建立了考虑水电站引水系统水锤效应的弹性水体水轮机模型,并据此构建了水轮机调速系统模型。针对水轮机调速系统具有参数不确定性、存在干扰等特点,运用H∞鲁棒控制理论,提出了水轮机调速系统H∞双回路鲁棒控制策略,以水门开度偏差为补偿信号构建了内环反馈回路,以发电机转速偏差为补偿信号构建了外环反馈回路。仿真结果验证了该控制策略的有效性,而且其时域性能指标明显优于传统比例–微分–积分(proportional integral derivative,PID)调节器控制效果。展开更多
基金Supported by National Science and Technology Major Project of the Ministry of Science and Technology of China(2016ZX05026-002,2016ZX05028-001,2016ZX05024-005)
文摘As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.
文摘建立了考虑水电站引水系统水锤效应的弹性水体水轮机模型,并据此构建了水轮机调速系统模型。针对水轮机调速系统具有参数不确定性、存在干扰等特点,运用H∞鲁棒控制理论,提出了水轮机调速系统H∞双回路鲁棒控制策略,以水门开度偏差为补偿信号构建了内环反馈回路,以发电机转速偏差为补偿信号构建了外环反馈回路。仿真结果验证了该控制策略的有效性,而且其时域性能指标明显优于传统比例–微分–积分(proportional integral derivative,PID)调节器控制效果。
