Presented at B4 Poster Session, 2:30 PM Tuesday David Barron, Afshin Pashaei, Mark Osborne, Dionysios Stamatiadis, Panos Xenos, Francesca Madia-Mele, Babis Marmaras, Daniel Schweer This paper presents the results of an in-depth system integration analysis of M-SSSC technology commissioned in the GB transmission system to provide real-time power flow control. National Grid Electricity Transmission (NGET) conducted detailed electro-magnetic transient (EMT) studies, as well as real time tests in a Control-Hardware-in-the-Loop (CHIL)configuration, to demonstrate the dynamic behavior of M-SSSCs under different operating scenarios and network configurations. In addition, a comprehensive set of Protection-In-The-Loop (PIL) studies were conducted using a real-time simulation platform to investigate the impact of M-SSSCs on existing distance protection schemes. The results of the EMT study analysis demonstrate the effects of series compensation devices on network power flows and confirm no adverse impacts on system integration. The PIL studies ascertain the value of the fast-acting bypass and demonstrate that the systems-level risks of affecting the operation of the existing distance protection scheme is low. This research contributed to: the improvement of M-SSSC controls and performance, ensured NGET technical specification compliance, and increased the confidence of the National Grid's engineers about the capability of this technology to provide boundary transfer increases without adding risk.