| Since the beginning of 1970's when the first domestic-produced 200MW steam turbine was put into operation, 200MW units have always been playing important roles in our national electric system,Until year 2000,several hundreds of 200MW units have been in operation in the large electric networks all over the country,which contributes a lot to the continuous an healthy development of our national economy and the improvement of people's living standard. As the 200MW steam turbine generating units were made by ways of copying the technology of pre-Soviet Union, there exists quite large gap in the design of equipment and the level of manufactuting compared to the generating equipment of developed countries.Traditional mechanic hydraulic type adjustment system was adopted in the control system of steam turbine,the system has many problems such as low sensibility, high rate of sluggish, poor load adaptability and low automatic level,which all lead hidden danger to the operation safety of the units. Based on deep study on the control system theory,characteristics and operation-mode of the steam turbine,this thesis has made an overall design on the control system of DEH,and its main functions include:rotational speed control,load control,over speed protection,coordinating control,etc.And the key topics are valve management strategy,rotor heating stress control strategy,ATC control strategy and swinging load control,etc.In the industrial experiment of gas turbine units in Shengli Power Plant,Xinhua's DEH system was selected as the control equipment of DEH adjustment system.The software in form-mode achieves rotational speed,load,over speedprotection,coordinating control,valve management and ATC control logic. All kinds of experimental data showed that the control system is of adcanced and reasonable design and of complete functions,it has made great improvement in the operating index of 200MW units,and has explored a new way for the modernization of old units. |
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