A novel hybrid analytical and numerical algorithm for solving the circulating current in enclosure of GIS based on the loop current method

In the gas insulated switchgear (GIS) system, the electromagnetic induction phenomenon causes the circulating current in the enclosure of GIS, called as the enclosure current (EC) of GIS. EC will lead to energy loss and conductor heating, and so it is harmful to the power system operation. To date, there exists no accurate and fast method to calculate EC. Based on magnetic field coupling analysis and loop current method, this paper creatively proposes a novel hybrid analytical and numerical algorithm, which not only can analyze EC of all GIS connection modes, but also provides a clearer physical insight about EC. Moreover, the numerical integration strategy, which is used to calculate inductance, brings higher calculation accuracy, especially to the loops with irregular shape. Compared with the simulation results of EMTP software, the error of proposed algorithm is less than 10%, which demonstrates its effectiveness.