Load flow and security assessment of VSC based MVDC shipboard power systems

The higher power density requirements in the future shipboard power systems are intended to be met by the adoption of Medium Voltage DC (MVDC) architecture. The MVDC shipboard power system is a typical case of the multi-terminal DC distribution system. Voltage Source Converters (VSC) with high voltage and power ratings and independent control over the real and reactive powers has many advantages over the current source converters and are best suited in the MVDC architecture for power conversions in the DC distribution network. A precise and efficient power flow is necessary for the MVDC architecture to determine the controls for VSCs and regulate the AC/DC systems. In this paper, the control modes of VSCs are studied, and the Newton-Raphson algorithm is employed to solve the AC-DC power flow of the MVDC shipboard power system containing VSCs. The power flow developed is used for security assessment based on a performance index that considers the MW flow violations over the DC cables.