Operation Optimization Of Cold End System For 600MW Thermal Power Unit

Thermal power units are still the main power generating units in China,and the operation status of the cold end system has a very important impact on the safety and economy of thermal power units,which is directly related to the benefits of thermal power enterprises.Therefore,the research on the operation optimization of the cold end system of thermal power units to ensure that the cold end system runs in the optimal state is of great significance for improving the economic performance of thermal power units and energy-saving and emission reduction.Taking a 600 MW thermal power unit as the research object,the research is conducted on two aspects: the establishment of the cold end system model and the optimization of operation.In terms of modeling,establish incremental power model of steam turbine,condenser variable-condition characteristic model,cooling tower model,circulating water pump system model,steam turbine-condenser coupling model,condenser-cooling tower coupling model,and finally establish the optimization model of the cold end system.In the modeling of the variable working condition characteristics of the condenser,aiming at the problem that the calculation value of the condenser pressure prediction model deviates greatly from the actual value due to the aging of the condenser equipment and pollution scaling after a period of time in the traditional modeling method of the variable working condition characteristics of the condenser,an RBF neural network condenser pressure prediction model based on historical operating data of the condenser is proposed.The results show that the maximum relative error of the model is 2.06%,and the average relative error is 0.65%,which can predict the condenser pressure well;In the cooling tower outlet water temperature calculation model,aiming at solving the nonlinear equations in the calculation process,based on the iterative method,the solution conditions and unique conditions of outlet water temperature of cooling tower are analyzed in detail,and the shortcomings of the iterative method are analyzed.A nonlinear programming genetic algorithm is proposed to solve the cooling tower model.This algorithm can avoid the problems of long iterative calculation time and high requirements for iterative step size and threshold in the traditional iterative method.Compared with the traditional algorithms,the nonlinear programming genetic algorithm has faster calculation speed and higher accuracy;In the modeling of the circulating water pump system,the optimal combination problem existing in the parallel connection of two different types of circulating water pumps,a multi-group genetic algorithm is used to solve the operating parameters corresponding to the optimal combination of circulating water pumps operating in a high-efficiency work area,and compare the power consumption of the circulating water pump under different operation modes,and the combined operation mode of the pump operation with the least power consumption of the circulating water pump under different flow rates is obtained.In the cold end system operation optimization,the operation is divided into safe operation and economic operation.In terms of safe operation,the change range of steam turbine exhaust pressure and the adjustment range of circulating cooling water flow under different variable conditions are studied.The results show that when the ambient temperature is too high,it is necessary to pay attention to controlling the minimum flow of circulating cooling water.When the ambient temperature is too low,it is necessary to pay attention to controlling the maximum flow of circulating cooling water;In terms of economic operation optimization,an optimization objective function under economic operation-Economic Benefits is established,and the optimization results are compared and analyzed with the net incremental power method.The optimal operating parameters and corresponding to different load rates and different ambient temperatures are obtained.According to the annual load curve and meteorological data of the unit,the annual economic benefit can reach one million yuan after the operation optimization of the cold end system of the thermal power unit.