Driven mainly by the Kyoto Protocol and the EU climate action (20-20-20 targets), the country members of the European Union have taken actions towards the reduction of emissions and the increase of the electricity generated by Renewable Energy sources (RES) [49]. According to studies of the European Network of Transmission System Operators for Electricity (ENTSOE), the participation of RES generation in the generation mix of Europe will be majorly increased compared to the present situation [2]. According to these studies a major contributor to this RES increase will be Germany. The German government’s energy transition plan [5], intends to replace most of the country’s nuclear generation with renewable energy generation. A large part of the renewable energy generation will come from offshore wind parks. These windparks will be located in the north of Germany, in the North and Baltic seas. This change in generation mix will affect the geographical distribution of Germany’s generation sites leading to possible threats for the secure operation of the German transmission system [3]. In order to overcome congestions in the transmission system the German Transmission System Operators (TSOs) have proposed the construction of four High Voltage Direct Current (HVDC) transmission corridors which will be embedded in the German transmission system. These HVDC corridors (termed A, B, C and D) will span from the north to the south of the country and will facilitate the transmission of the large offshore wind generation in the north to the large load centers in the south. This MSc thesis focuses on studying the effect of Corridor A on the transient stability of the transmission system. Due to the proximity of Corridor A to the German border with the Netherlands and thus the proximity of its HVDC converter stations to the Dutch transmission system it is interesting to see if and how this HVDC corridor affects the transient stability of the German as well as the Dutch transmission system. An analysis of the control parameters of the VSC-HVDC under various faults in the AC system is implemented in order to examine their effect on the voltage of the AC network and the rotor angles of the system’s online generators. The grid code compliance of Corridor A with the short circuit current contribution and its effect on the system’s voltage and rotor angle response of its generators will be observed. Additionally this thesis studies the effect a sudden loss of Corridor A will have on the power tie-line power between the Dutch and German power systems and the rotor angle stability of generators located both in the Nethrlands and Germany. In order to perform the aforementioned studies time-domain simulations will be performed using Siemens PTI’s software tool Power System Simulator for Engineers (PSS®E).