On Optimization Design And Application Of The Coordinated Control System Of350MW Supercritical Units

The advocacy of energy saving and pollution reduction during National EleventhFive-Year Plan propels the development of supercritical units. With the rapid development ofscience and technology and electric power industry, for the thermal power plant industry,China has adopted the policy of encouraging large projects and discouraging smallenergy-inefficient power plants, promoting the development of supercritical units, since thesubcritical units under100MW with high coal consumption, high emission and lowefficiency are shut down while the supercritical units with large capacity, high parameters,low coal consumption and low emission are advocated vigorously. The control system ofsupercritical units is an important part of supercritical power generation technology. And thecoordinated control system of supercritical units is to establish the equilibrium of supply anddemand of power, which is the core of the whole control system. The key concept of thecoordinated control system is to treat boiler and turbine generator as an entity to control andto operate the coordinated control meeting both the requirements of load demand of electricnetwork and the operation parameter deviation of units. This system can ensure that unitscan respond to the load demand of the electric network and the stability of main operatingparameters of the units. Such a system plays a key role in the security, stability and economicperformance of the units.The author of the thesis first introduces and analyzes the component parts and theirtypical design of the coordinated control system of the supercritical units of2×350MW inthe first phase optimization project in Huaneng Ruijin Power Plant participated by the author.Then, it goes on to introduce the components of the supercritical unit of350MWcoordinated control system, including the master control of boiler and turbine and theoptimization method of coordinated subsystem--the main steam temperature contol system.The feedforward-feedback and non-linear control strategies are applied to the master controlof boiler and turbine. According to the changes of the outer electric network and steampressure, boiler is able to make a swift adjustment of the demand of fuels and then changethe flow rate to satisfy the power demand by selecting rationally the feedback signal of boiler master control, The application of the pressure pullback and load deviationfeedforward signal enables turbine to make adjustment of the opening of main steam controlvalve; and then change the actual power according to the changes of the load of electricnetwork. The state observer, the advanced strategy, is applied to the main steam temperaturecontrol system of supercritical units. Finally, it gives a detailed introduction to the workingmethod of logical configuration by applying Xinhua XDPS-400+DCS and presents completeconfiguration logics. By means of tuning of the configuration logics after the optimization,the parallel operation of the two units in the first phase of the project went into respectivelyin2010.4and2010.6and conforms to the related standards.The supercritical units of2×350MW in Ruijin Power Plant are the first domestic ones;therefore, this research is has reference value for the design of the control system of boiler,turbine and main steam temperature.