Frequency-independent circuit model of earth return effects in transmission systems

The paper presents an alternative method of calculating the impedance correction terms of an overhead transmission line by taking into account the effect of the earth return. A circuit-based model is proposed that is frequency-independent and can provide the linear parameters of the earth return path. To demonstrate the validity of the model, the theoretical current distributions under steady-state and transient conditions are calculated. The results obtained are compared with values derived using Carson´s formula and finite-element analysis. The results are in good agreement. The model is simple to implement, has short computational times, and compared with other approaches it provides a straightforward calculation that has direct physical meaning. The model can be easily adapted into any transient analysis program and used to predict the surge characteristics of the system