Introduction of Containerized STATCOM up to 200Mvar Rating

In this paper, the physical transmission network structure of the East Coast grid is analyzed, and the risk of generator out‑of‑step (loss of synchronism) under N‑2 contingencies on major 765 kV transmission lines is examined. The analysis confirms that, under severe fault conditions, a significant generation constraint of approximately 6.8 GW is unavoidable due to a pronounced degradation in voltage stability. Consequently, the necessity of dynamic reactive power compensation to mitigate these constraints is evaluated.

Through comparative simulations conducted before and after STATCOM installation, it was verified that mitigating voltage sags below 0.6 pu secures the Critical Clearing Time (CCT) and prevents generator tripping. In particular, the deployment of STATCOMs at key 154 kV substations was shown to significantly improve local voltage stability, indicating that generation constraints can potentially be mitigated by up to 500 MW. Based on these findings, a 200 Mvar modular and containerized STATCOM solution is presented, which has been implemented at the Hongcheon substation, where site and environmental constraints are pronounced. To ensure high‑voltage insulation clearances, a phase‑segregated container configuration was adopted. By employing this segmented container approach, the limitations of standard containers are overcome, and an expanded layout is provided, offering an internal maintenance space exceeding 1,000 mm and enabling indoor maintenance.

Furthermore, sustainability is ensured from an ESG perspective by minimizing on‑site works, thereby reducing carbon emissions and enhancing occupational safety. This case study demonstrates that containerized STATCOMs represent a practical and scalable solution for alleviating generation constraints and improving power supply reliability.