Thunder and lightning (also known as "lightning") is a kind of long distance instantaneous discharge in thunderstorm weather. According to the statistics, the lightning of 1/3 will hit the earth. The lightning discharge generated in the process of high peak current, high peak power, the high temperature, strong electromagnetic radiation and shock wave physics effect, ground building, electrical and electronic equipment, aviation, aerospace, communications and other damage, and even a threat to human life [1-2]. In the transmission line, the lightning overvoltage caused by lightning static induction and electromagnetic induction seriously affects the normal operation of the equipment. As a commonly used lightning protection device, ZnO varistors are widely used in the field of [3-6], which has the characteristics of large current capacity, low residual voltage and short response time. Many scholars at home and abroad have on ZnO varistor in the application of surge protection in the experiment and done a lot of theoretical research: Li Xiangchao, Tang Hongke, Wang Jinhu et al. Study on the lightning current through the decoupling inductor, the residual voltage surge protection device can reduce 15%~30%, effectively improve the protective effect of surge protector [7]; Li Xiangchao in the distributed control system of surge protection device design patent, proposed the use of inductance as a decoupling element, can effectively reduce the residual voltage surge protection device [8]. Wang Huiying in the surge protector with energy application, using transmission line theory to analyze the relationship of energy cooperation, and compared with the equivalent inductance. The above scholars of multilevel surge protector how to improve the protection effect to do research, but no further research on the two level ZnO varistor series decoupling inductance at all levels of residual pressure and flow. Decoupling inductance values in the two levels of the same application of surge protective device, the residual pressure, flow and absorb energy in the practical application of lightning protection and has the certain reference value [9-12].
The decoupling inductor used in multilevel surge protection system, the lightning current impulse simulated platform of 8/20 s, surge protection system consisted of two ZnO varistor series different decoupling inductance of impact test, obtains two levels of the same reference voltage ZnO voltage sensitive resistor with the application, the first level ZnO varistor and second ZnO varistor flow, residual pressure and the corresponding relationship of energy absorption. It provides the basis for the application of the decoupling inductor in the multistage SPD system.
Theoretical analysis of two series ZnO varistor series inductors in series 1
2 test plan and test data analysis
2.1 test plan
2.2 test data analysis
Paper summary:
Through the combination of transmission and test wave, analyzed on the two level of ZnO varistor with energy in detail, through the impact tests with different inductance values two ZnO varistor flow value, and the relationship between the energy value of the residual voltage, and comparative analysis of the above test data, draw the following conclusions:
The experimental results show that the flow of the first stage SPD is much higher than that of the first stage SPD, which is composed of two ZnO varistors, and the first stage SPD has the effect of the discharge of in the two stage SPD system.
Under the same impact voltage, the greater the inductance value L, the more the first level SPD to the total current, the better the discharge effect.
The impact of the 5~14kV voltage range, inductance L is larger, second SPD flow and residual pressure gradient is small, has very important significance on lightning protection of power system.
The first level SPD energy absorption percentage within 30%~40%, second SPD energy absorption percentage is about 5.5%~12.5%, the first SPD to absorb a lot of energy, at the same time, with the inductance value of L increases, the percentage of second levels of energy absorption decreased gradually. More effective implementation of the coordination and protection between the two SPD.