This paper proposes a new modeling of monopolar HVDC (High Voltage Direct Current) link for harmonic load flow analysis in electrical power systems with explicit representation of the DC and AC networks, as well as the converters non-linear characteristics and their harmonic interdependences, ensuring an accurate solution using current injection equations in frequency domain. This new methodology allows the analysis of generation and propagation of harmonic voltages and currents components, produced by the rectifier and inverter of the HVDC system. The proposed model is validated against time domain simulations in ATP (Alternative Transients Program).