Analysis of Generator Loss of Field Fault in Nuclear Power Plant Control Rod Power System
Xiao Xiangtao1, Hao Liangliang1, Liang Zhengqiu1, He Peng2, Wu Pengfei3
1. School of Electrical Engineering Beijing Jiaotong University Beijing 100044 China; 2. Liaoning Hongyanhe Nuclear Power Co. Ltd Dalian 116001 China; 3. Yangjiang Nuclear Power Co. Ltd Yangjiang 529599 China
Abstract：Nuclear power plant control rod power is the only power supply system of control rod drive mechanism, to ensure the safe and reliable operation of this system is of great significance to improve the safety of nuclear power plants. The principle of loss of field protection is simple, and many mismatch events of loss of field(LOF) protection have occurred on site; the operation state of the control rod power system generator is different from that of the conventional grid-connected generator; In order to effectively solve the loss of field protection mismatch problem, this paper has carried out the qualitative analysis and quantitative analysis of the loss of field fault of the generator in control rod power system. Firstly, it is assumed that the RAM unit has sufficient reactive power support capacity and ignores the magnetic leakage between stator and rotor and the sub transient process caused by damping winding, and the general expression of longitudinal potential is obtained on the basis of the equivalent circuit of RAM system and the mathematical model of generator. Since the variation quantity of power angle of fault-unit essentially reflects the accumulation of the speed difference between two units in time dimension, the loss of field development process is divided into equal power angle phase, asynchronous operation phase and periodic asynchronous operation phase according to the slip rate and power angle characteristics. Fault-unit generator can be regarded as synchronous operation in equal power angle phase, while normal-unit generator can be regarded as synchronous operation in asynchronous operation phase and periodic asynchronous operation phase. After that, according to the segmentation method of the loss of field process of RAM units and taking the longitudinal potential as the starting point, the analytical expressions of electrical quantities in each phase are obtained from the longitudinal potential variation law in each stage and the basic equation of generator. The specific analytical process is given by taking the sudden complete loss of field voltage of RAM system as an example. In order to fully verify the correctness of the analytical results of loss of field, experimental verification and simulation verification are carried out respectively. Through the experimental data of partial loss of field in an actual nuclear power plant under light load level and combined with correct simulation model, the actual simulation values of active power and reactive power of the field loss unit are compared with the theoretical analysis values and the results are found to be very consistent, which verifies the correctness of analytical results of equal power angle phase after loss of field. Furthermore, the simulation model verified by the experiment is used to simulate the fault of complete loss of field under two-generator parallel operation and full load level, and the simulation parameter settings are that total simulation duration is 100s and one RAM unit loses field voltage at 20s. The results show that, the variation of electrical quantities in each phase is consistent with theoretical analysis, and the loss of field process of RAM system generator is significantly different from that of grid-connected generator. The analytical process of loss of field fault lays a theoretical foundation for the formulation of generator loss of field protection plan of the control rod power system.
肖项涛, 郝亮亮, 梁郑秋, 何鹏, 吴鹏飞. 核电站控制棒电源系统发电机失磁故障解析[J]. 电工技术学报, 2023, 38(3): 770-780.
Xiao Xiangtao, Hao Liangliang, Liang Zhengqiu, He Peng, Wu Pengfei. Analysis of Generator Loss of Field Fault in Nuclear Power Plant Control Rod Power System. Transactions of China Electrotechnical Society, 2023, 38(3): 770-780.
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2023, Vol. 38 
