This paper presents a novel method for harmonic analysis that uses techniques both in the time and the frequency domain. The linearparts of a network are modelled in the frequency domain, while the non-linear ones (converters, saturable transformers, etc.) can be modelled more easily in the time domain. Harmonic balance equations in the multi-frequency domain are set, and solved by a Newton-Raphson iterative procedure, with which it is easier to study cases with problems of convergence.