The Impact Analysis When Large-capacity Nuclear Power Plant Connected To The Grid

The technique of nuclear power is increasingly improved. The nuclear electrical machine is widely integrated to the power system in large scale. Because of the large unit capacity, high security requirement, influence of system disturbance and long time of shutdown process, the integration of nuclear generator has a strong impact on power grid. Load shedding and generator cutting of nuclear plants lead to a large active power shortage of power system, which is harm to the system frequency and node voltage. And the nuclear generators are sensitive to the voltage flucation and frequency variation. Power system fault may cause the generator triping of nuclear plant, which deteriorates the situation of system fault. Therefore, researches on the interact influence of nuclear plant and power system have the vital significance.Considering the nuclear power development strategy and the nuclear medium and long-term development planning, the necessarity of developing nuclear power in China is illustrated. The basic pricinple of nuclear plant operation is given and the detailed mathematical model is established. Temperature effect of neutron kinetics module, the temperature dynamic models of fuel and coolant are considered in the reactor core equation. In power control system, steady-state mathematical models are determined for constant average coolant temperature and constant steam pressure of two circuit. And coolant pump, turbine and governor models are also given.Researches on the interact influence of nuclear plant and power grid are carried on. The effects of voltage flucation and frequency variation on the operation of nuclear generators are analyzed. And the effects on power system are also given under different integration method and operation modes of nuclear plants. The Haiyang nuclear plant is taken as an example. The effects on power system under the conditions of line faults, bus faults and genenrator cutting are simulated. The results prove that only the transformer bus faults cause the angle instability of nuclear generators which leads to cut the units with keep the system stability.With considering the practical system operation mode of Shandong power grid, the effects on power system are analyzed under the integration of nuclear plant. And the stability of nuclear generators under transimission line faults is simulated. The simulation results verify that with connecting ultra-voltage transmission line and HVDC, the power supply ability of Shandong power grid is much improved. And under major simulated faults, nuclear generators can keep the transient stability without unit protection action.