Study On Modeling And Simulation For The Secondary Loop Of The Nuclear Power Plant

With the rapid economic development, China's energy and environmental issues have become increasingly prominent. As an important component of the world energy, nuclear power has a large capacity, low emission, low price and many other advantages. Therefore, developing nuclear power rapidly has become an important part of China's energy strategy. "The topic of nuclear power development planning of state (2005-2020)" planned that by 2020 the total installed capacity of nuclear power stations will be increased to 40,000MW and the total nuclear power installed capacity of electric power will be increased from the current proportion of less than 2 % to 4%. In this context, the independent development or introduction of foreign advanced nuclear power technology to enhance the operational safety and the economy of nuclear power plants is an urgent need to be addressed. As a result, continue to strengthen the research of operation and accident of nuclear power units is of great importance to promote China's nuclear power development.The model using the nodes pressure as state parameters is a common one of the thermodynamic system model, which can meet the conditions in most of the simulation requirements. However, the numerical problems may arise in low-flow system: the error of the pressure state variables lead to inaccurate pressure so that the flow calculation fails to comply with the law of the case. In order to solve this problem, usually the sub-processing method has been used: there will be an amendment in low-flow system. Another method is to use the pressure difference between adjacent nodes as state parameters, this can make the model more complete and can improve calculation accuracy under low-flow system.In-depth analysis of MMS simulation modeling software, the secondary loop dynamic model using node pressure difference as state parameters was set up according to the actual characteristics of the system based on equipment module division. This thesis also tested each model and system-the second loop of the actual nuclear power station(the second term),computed the balance point,tested the performance of step disturbance and runback loads for system(no adding adjustment system).The simulation result shows that the model can get high accuracy and reasonable transient behavior and the validity of this modeling method is proved that using the node pressure difference as state parameters. At the same time, a comparative analysis was made between two simulation tests. It shows that this method can lead to faster computing speed in the transient course calculation of low flow conditions and wide range work conditions.