Energy-saving and improving energy utilization efficiency are common concerned topics of the whole world. Control quality of reheat steam temperature is an important factor for thermo economy, which is mostly controlled by mankind and leads to uneconomical operation. One of the reasons is unsuitable controller parameters, causing by inaccurate models. In this paper, reheater model was established based on single-phase heat-exchanger thermal system dynamics. And parameters of the model were determined by design manual. Simulation on a 1000WM unit showed that, the model had good dynamic and steady performance.
This paper presents a real-time pollution monitoring model of convection heating surfaces based on coal online soft sensing, This model reality the optimization calculation of clean factor and get the information of coal moisture, ash content and ultimate only according to the existing measuring points and data in the Distributed Control System (DCS) of thermal power plants, no need to use additional equipment. Used this technique in 1000MW power units and the result shows that, the computational accuracy of clean factor has greatly improved, which will correct the boiler blowing operation.
This paper designs the pitch controller synthesis to ensure the stability and the controllability in the whole regions as the power grid scheduling instructions. Because of the wind speed measurement and accurate system model are hard to obtain, the range that the actual working point deviating from the balance point is very large, so that the system dynamic performance cannot be described with linear time variable (LTI). This paper utilizes the linear matrix inequalities' techniques (LMI) to design LPV (linear parameter varying) gain-scheduled controllers based on criteria, which provide guarantees of stability performances along the whole reference trajectory. The LPV pitch controller replaces the traditional speed controller to dynamically compensate the pitch angle. According to the errors between the power grid scheduling instructions and measuring the output power, power controller adjusts generator torque to achieve the adjustable power in the whole regions. In view of unmodeled dynamics and wind speed random disturbance, the feed forward linearization. robust pitch regulation using extended state observer (ESO) is proposed to restrain comprehensive disturbances. The proposed controller is seen to be more efficient.
Combined with the thermal system analysis, the mathematical model for selecting the optimal initial pressure of the power unit is established based on the comprehensive consideration of the effect of main steam pressure on governing stage efficiency, steam feed pump consumption and flow passage efficiency. Then the steam pressure with the maximum unit efficiency is searched using variable condition calculation. With quantitative calculations of N600-16.7/537/537-I unit of Pan Shan thermal power plant taken as an example, the optimal initial pressure is obtained by exhaustive method around the 75% load point. The results reveal that the unit power, heat absorption and unit efficiency all increase with the increase of the main steam pressure. However, the increasing velocity of efficiency is less than heat absorption when main steam pressure attains to certain value, which makes the unit efficiency begin to decrease. Therefore, this main steam pressure is the optimal initial point to be searched.
For the problem of the abandoned large-scale wind power currently, in order to improve the utilization of wind power and make full use of wind resources, a method of using wind power to heat the condensed water through electrothermal furnace is proposed. On the basis of mass and energy conservation, through analyzing variable condition of the regenerative heating system and water-cooled condenser, the dynamic mathematical model is created and then the dynamic influence of condensed water temperature on the economy of thermal power plant is studied. This paper, taking a typical 660MW water-cooled unit as an example, discusses the dynamic characteristics of steam turbine and energy-saving effects of this method. Results show that obvious economic effects can be obtained through non-grid-connected wind power heating the low-pressure condensed water, which can reduce the steam extraction flow from steam turbine, improve the thermal efficiency of thermal power plant and save the amount of coal. It has positive significance to digging energy-saving potential of plant.
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