Research on Surge Immunity for Numerical Protection Devices
Zhe Zhang · Power System Technology · 2008
The mechanism of occurring surge disturbance due to the single-phase earth fault of high voltage bus caused by lightning stroke on substation and the feature of surge disturbance is analyzed, the intensities of common mode signal and difference mode signal as well as the frequency spectrum of surge disturbance are quantitatively researched. The surge immunity tests for numerical protection devices are presented. According to the definitions and features of ports in numerical protection devices, the countermeasures against surge disturbance are proposed, the influence of surge disturbance on secure and stable operation of numerical protection devices and corresponding solutions are researched by case study. Analysis results show that both power ports and communication ports of numerical protection devices are easily affected by surge disturbance, thus a better solution should be applied in the links of design, production and operation of numerical protection devices.