Stability Management and Design for DC Electric Power Network and Systems

Electromagnetic mechanical circuit breakers are used as protection circuits in various systems. Once these operate, they put stress on the circuit breaker and need to be replaced. The Space Power Systems use electronic switches that use power semiconductors. Even if an electronic switch using a power MOS FET detects an overcurrent due to a short circuit or failure, it takes about 18 (µsec) from detection to shutoff in experiments. In addition, transient currents in the load's inductor or fault current propagation from downstream can cause an unexpected hypersensitive response in the electronic switch, causing the entire system to trip off. To avoid this unexpected nuisance tripping, the power system of the International Space Station Japanese Experiment Module has a current-limiting function added to the semiconductor circuit breaker. However, relying solely on the current limiting function of semiconductor switches for stability management of a DC power network is risky from a stability management perspective. This paper proposes the following two points as methods for Stability Management and Design for DC Electric Power Network. The first method is to employ a semiconductor switch with a current limiting function, and the second unique method is to manage the impedance of power equipment and loads from the perspective of stability management of the DC power network. What is impedance management? This means considering the DC power network as a control system and starting the design and management of system stability from the basic design. The stability of the entire system can be evaluated by collecting equivalent circuits of the power supply system and load and simulating the impedance and phase characteristics of the entire system, and by actually measuring the impedance and phase characteristics of the power system. With this method, the larger the system, the more it is possible to evaluate the stability of the system by measuring the system's impedance and frequency characteristics without applying stress to the final product through transient response tests.