Fast 3D direct lightning shielding protection computation methods

The two EGM based direct lightning shielding methods presented in IEEE Standard 998 are the rolling sphere method and the revised EGM Method. The application of the rolling sphere method described in the IEEE Standard is using 2D drawings to simulate the 3D space environment and is limited to using the same strike distance for all objects in the system. The SBSHLD program based on the revised EGM is an analytical approach which is restricted to some special configurations of masts or shield wires. This paper presents a fast 3D computer program based on the EGM using a collection surface method. It yields identical results to those obtained using the rolling sphere method and can apply to any shape of structure or substation. It can also use different strike distances to horizontal or vertical objects. The example 69kV substation described in IEEE Standard 998 is used to demonstrate usage of this program.