基于减温水调节阀门流量特性补偿的汽温控制系统优化

蒸汽温度控制回路的调节品质对火电机组的安全、经济运行至关重要，而执行机构的流量特性直接影响控制系统调节品质。通过分析常用的线性阀门、等百分比阀门和抛物线阀门流量静态特性，并结合控制系统和控制参数的整定分析方法，指出了选用线性调节阀可使控制系统在不同阀门开度下系统调节性能不变，对提高调节系统稳定性最为有利。为了提高实际运行过程阀门开度与流量的线性度，给出了调节阀门流量特性的补偿原理和阀门流量特性补偿函数的求取方法。以某660 MW亚临界机组为例，利用历史数据求取了两侧调节阀门流量修正函数，并对控制回路进行了流量补偿优化。运行实践表明，锅炉过热汽温调节回路经过流量补偿优化后，过热汽温调节品质有了明显的改善。最后，指出了对阀门流量特性进行补偿校正应作为设备检修、维护的定期工作之一。

Optimization of the Steam Temperature Control System Based on the Flow Characteristic Compensation of Desuperheating Water Regulating Valve

The regulation quality of the steam temperature control system is of great importance to the safety and economical operation of thermal generation units. Particularly, the flow characteristics of the governing valve actuator directly affect the regulation quality of the control system. In this paper, through the analysis on the flow static characteristics of linear, equal percentage and parabolic valves and in combination with the tuning of the control system and parameters, it is concluded that the linear governing valve can maintain the regulation quality unchanged at different valve openings, which is good for the improvement of the control system stability. To improve the linearity degree of the governing valve in practical operation, the flow characteristic compensation principles and the calculation methods are put forward. Taking a 660-MW subcritical thermal generation unit for example, the flow characteristics of the A/B governing valves are calculated with the historic data of position and flow, and the flow compensation is applied in the steam temperature control loops. The unit operation result indicates that the regulation quality of the superheated temperature control loops is substantially improved. Finally, it is suggested that the flow characteristic compensation and correction of the valves should be taken regularly as part of the equipment maintenance.