Cost-effective sensor for residual current detection in residential DC microgrids

Several developments in the fields of power electronics and materials science have turned direct current (DC) power grids, which have remained in the background until now, into attractive alternatives to the existing alternating current (AC)-based power grids. Although the transition to DC is currently conceivable on a smaller scale as household microgrids, these installations still require reliable and reasonably priced protection devices to ensure electrical safety. The problem is that several existing technologies that have served us well in AC power grids do not work with DC. To ensure the electrical safety of DC networks, several smart power semiconductor switch-based fast DC circuit breakers have appeared on the market, combining the features of a circuit breaker, a smart relay, and an energy meter. However, in most cases, such combined circuit breakers lack the feature of measuring the fault current, which is crucial from the point of view of electrical safety. The reason is the high price of these sensors and their rather large dimensions, which prevent the creation of compact devices. This article examines the possibilities of creating cost-effective residual current sensors, based on integrated magnetometers, and evaluates the usability of such sensors in potential household DC microgrids, based on the prototype created.