Multi-terminal Medium Voltage DC Distribution Network Large-signal Stability Analysis

The Brayton-Moser’s mixed potential theory is a popular approach for large-signal stability analysis of DC-based systems with constant power load (CPL). The criterion from the conventional mixed potential theory contains multiple time-varying parameters which are complicated for convenient stability analysis hence the need for simplification. On the other hand, stability analysis of droop-controlled multiple source converter-based DC systems are scarce. Thus, the large-signal stability criterion of a scaled-down droop-controlled multi-terminal MVDC distribution network with CPL using Brayton-Moser’s mixed potential theory was simplified and derived to show that CPL power rating, PI control parameters, droop and damping coefficients have profound effects on the system’s large-signal stability. By way of MATLAB/Simulink simulations, the large-signal stability of the MVDC distribution system was observed to reduce with increase in CPL power rating and source converter droop coefficients as well as increase with increase in proportionate coefficient values and use of optimized unlike non-optimized damping coefficients. Therefore, the droop-controlled MVDC distribution network with optimized PI control parameters, droop and damping coefficients have enhanced dynamic response and large-signal stability margin proving the accuracy and validity of the simplified large-signal stability criterion.