To Improve The Control Quality Of AGC And The Influence Of Thermal Power Generation Units

With the development of China’s economy, the difference between electricity peak and valley keep increasing, power grids generally require large capacity thermal power units take part in peak load operation grid according to the demand for electricity in a large range of load regulation and peak depth. As State Electricity Regulatory Commission take more supervision and regulation on electric power market, North China Electric Power Supervision Bureau introduced the "Two Rules" ("Implementation details of the operation management of the regional power plant in North China "and" Implementation details of the auxiliary service management of the North China regional grid connected power plant ") firstly in 2008 on the unit set AGC regulation quality to put forward quantitative performance criteria.The boiler’s lagging role is the main control factor for the unit of AGC to improve, how to optimize the unit of AGC to satisfy the load of the fast and accurate and sensitive in the power grid, which also put forward more stringent requirements for the entire process control process coordination, and even the coordination of the power plant.Good AGC regulation performance can make the power plant aloof the checkup from the "Two Rules" of the assessment, which will also get the money, the amount of electricity from power grid. However, it needs a faster load response and shorter load response time and frequently load adjustment in a large range,which also bring the following problems:First, frequent change of main steam pressure,sometimes even pressure’s fluctuation above a MPa, which will lead to a decline in economy of the power plant and increasing of coal consumption. Especially, in large air cooling unit, in can caused the back pressure’s fluctuation, and reduced cycle efficiency, even increased the power consumption rate of plant; In the same time, frequent change of temperature and pressure reduced the lifetime of pressure retaining parts.Second, faster load response speed, shorter response time and frequent load adjustment, will lead to adjust the valve frequent fast and accurate action, which may cause frequent fault of EH oil system and valve’s jam, even turbine’s control performance degradation; Load often swing, which cause regulating valve hydraulic fault or electronic control device’fault sometimes. All of these will threat the turbine to the safe operation, even lead to the accidents of equipment;Third, for air and pulverized coal distribution system, the frequent change of load represents frequent change of air and pulverized coal. Because of the difference in the matching of air and pulverized coal, the formation of the nitrogen oxides increased, which makes the operation cost of the power plant increased in today’s increasingly serious environmental protection situation.The object of this study is Inner Mongolia JingLong Power Generation Co. Ltd. with 2 x 600MW units. The writer used CFD numerical simulation technology in base on actual operating conditions of power plant, found out the way to improve the performance of AGC regulation in a comprehensive way,and the impact which the way will be caused on the economy and safety of the unit, and finally to find a reasonable range which is compatible with the relationship between the three.