Research on Analysis and Application of Lightning Current Model in Power System and Protection Improvement method

Non fault lightning strike is an important reason for the inconsistent action of double sets of protection for 500kV and above lines. The protection identifies the waveform of non fault lightning strike as the fault in the area. The differential protection of partial line protection acts, and the line is cut off to cause short-time power loss of the line, which affects the protection reliability and power supply reliability. In this paper, the influence of non fault lightning strike on relay protection equipment is analyzed and studied. Combined with the actual lightning strike fault, the small step simulation system of RTDS platform is used to standardize the lightning current modeling, and the line transmission model is established according to the tower parameters and equipment parameters of the actual line. Inject lightning wave into the line to study the propagation of lightning wave on the line. The lightning wave appears multiple catadioptric reflections between the two stations. By simulating the sampling frequency of the protection device, the sampling simulation waveform of the protection is obtained, which is compared with the actual lightning waveform. By changing the position of the injected lightning wave, the law and waveform characteristics are analyzed, and the amplitude and pulse width are summarized. In this paper, an improved method for lightning protection of protection device is proposed, and the ability of lightning protection against maloperation is enhanced by adding voltage criterion, raising protection threshold or extending protection setting value, or adding waveform identification criterion. Through the test of the protection prototype, the improved method is tested and evaluated.