Based on the actual needs of the transformation of 500 kV smart substation

this paper designs the bus overvoltage monitoring device based on series connected capacitor and the arrester discharge current monitoring device based on broadband pulse current transformer

and analyzes the key factors such as the measurement accuracy of voltage transformer with series connected capacitor and the influence of cable inductance on the measurement signal. Based on the actual parameter of 500 kV substation

the appropriate design parameters are selected

and the measurement accuracy of the monitoring device is verified on site. The monitoring device designed in this paper has complete functions

and can realize high amplitude and high frequency over-voltage and over-current monitoring. It has been applied in the project of 500 kV smart station

which can provide support for fault analysis and insulation design

and is of great significance to ensure the safe and stable operation of power grid.