This paper defines a three level 48 pulse STATCOM based on GTO-VSC which is used to support the integration of remote large offshore wind farms into the main onshore grid using line-commutated high-voltage dc connection (LCC-HVDC). This mature transmission technology requires a large quantity of reactive power. In order to enhance the dynamic performance of the LCC-HVDC connected to a weak system, this work presents STATCOM applications to improve the power quality and to avoid commutation failures. Simulation results show that HVDC LCC technology connected to a weak system needs extra reactive power compensation. It confirms the STATCOM performance and its dynamic and fast reactive power compensation during voltage fault conditions. Finally, the sizing of the STATCOM dc capacitor is studied.