This paper deals with the design and evaluation of a quadratic optimal control method based on bilinear state-space modelling approach in order to improve the asymptotic stability of Voltage Source Converter (VSC). An steady-state mathematical model of the VSC converter is developed around operating point. VSC converters are increasingly popular with the development of HVDC connection and Multi Terminal DC grid (MTDC). The main role of the studied VSC converter in VSC-HVDC transmission system is to regulate the DC bus voltage. The intention of this paper is to propose a rigorous control method based on optimization algorithms. Finally, the proposed control method is evaluated using Matlab/Simulink.