Research Of Steam Turbine DEH Valve Control

With the development of China electrical industries, the growth of power system capacity and the gradual expand of power system between the peak and valley, the components of power system is also changing accordingly. Many giant thermal power generating units have been participated into the adjustment of the peak and valley of power system. In modern generator units, DEH control system has been used in all of the steam turbines in order to achieve the unified management and control of all steam valves. In order to improve operation economical efficiency, it’s really necessary to improve the management links of the steam turbine valve. The main task of this thesis is as follows:Firstly, the composition, working mechanism and function of the turbine regulating system are described briefly. Base on the data of the load rejection test, the valve closing time test, the valve tightness test, over-speed test and OPC test, the actual performance and the influencing factors of the regulating system are analyzed deeply..Secondly, the mathematical model of valve flow characteristic of the DEH system is built and the non-linear part of model is discussed and processed linearly. In order to complete the optimization of the valve flow characteristic curve, the equation of the characteristics of single regulation steam valve is built up by using BP neural network. Under the management mode of single valve and sequence valve, the change data tables and curves of the valve flow and valve opening are obtained based on the least squares method.Finally, the setting test of turbine valves are finished, and the data of test is the reference data for the steam turbine valve characteristic setting optimization. After that, theoretical data of turbine valve characteristic settings optimization is calculated based on the single regulation steam valve characteristics equation. The new valve flow curve is gentler than former. The new valve characteristic has been used in Unit and Unit vibration is significantly improved by comparing single-unit. It has became better in primary frequency, lowered its heat consumption, reduced its inlet valve throttling losses and increase its stability and economical efficiency.