Series Compensation for DC Microgrid Stabilization Utilizing T-Type Modular Dc Circuit Breaker

Abstract

Dc microgrids during voltage transients or load power changes are prone to instability due to the negative impedance characteristics of the constant power loads (CPLs). The newly proposed T-Type Modular Dc Circuit Breaker (T-Breaker) integrates current breaking, current limiting and grid transient compensation functions into one device thanks to its integrated energy storage and modular multilevel converter structures. Much like the current and voltage compensations in ac systems, the T-Breaker can help the ride-through of grid transients by implementing shunt (current) and series (voltage) compensations. This paper focuses on the series compensation function of the T-Breaker which can insert or absorb voltage. Related system modeling, small signal analysis, large signal analysis, simulation are presented here. Experimental validation result on a scaled down system is also presented to show how the compensation improves the microgrid’s stability.