T-Type Modular DC Circuit Breaker (T-Breaker) as a Compensator for Future DC Grids

Abstract

When ac and dc microgrids get exposed to load power changes or voltage transients, instability could occur owing to constant power loads’ (CPLs) behaviour. CPL has the negative impedance behaviour which is the reason behind such instability. A flexible alternating current transmission system (FACTS) devices are used in ac grid to help improve the power quality under such circumstances. Contrarily, dc networks doesn’t have such devices and suffers under similar situations. In this paper, the T-Type Modular Dc Circuit Breaker (T-Breaker) is proposed to act as a compensator device for dc networks when energy storage is integrated. Its compensation functions in addition to breaking and limiting a system’s current can be achieved using this single device. By implementing the T-Breaker’s shunt (current) and series (voltage) compensations, ride-through of grid transients can be achieved. T-Breaker’s series compensation function and how it can be integrated with the shunt compensation to improve the stability of a dc microgrid is the focus in this paper. In addition to modeling and simulating the system, both small signal and large signal stability are analyzed. Furthermore, a scaled down 270 V 5 kW system is utilized to validate T-Breake’s compensation functions and their influence on a microgrid’s stability.

Keywords

• T-Breaker
• series compensation
• series-shunt compensation
• DC microgrid
• constant power load
• solid state circuit breaker