Disconnection of a string carrying direct current power

摘要

A direct current (DC) power combiner operable to interconnect multiple interconnected photovoltaic strings is disclosed. The DC power combiner may include a device adapted for disconnecting at least one photovoltaic string from the multiple interconnected photovoltaic strings, each photovoltaic string connectible by a first and second DC power line. The device may include a differential current sensor adapted to measure differential current by comparing respective currents in the first and second DC power lines. A first switch is connected in series with the first DC power line. A control module is operatively attached to the differential current sensor and the first switch. The control module may be operable to open the first switch when the differential current sensor measures the differential current to be greater than a maximum allowed current differential, thereby disconnecting the photovoltaic string from the interconnected photovoltaic strings.

主权项

1. An apparatus comprising:
a differential current sensor configured to measure differential current of at least one photovoltaic string of a plurality of photovoltaic strings, the differential current measured by comparing respective currents in a first direct current (DC) power line and a second DC power line that interconnect the at least one photovoltaic string to the plurality of photovoltaic strings; a first switch connected in series with the first DC power line; a second switch connected in series with the first DC power line and in parallel with the first switch, wherein the first switch has a lower on-resistance than the second switch; and a controller circuit configured to operate the first switch or the second switch in response to the differential current sensor measuring the differential current at a different level than a predetermined current differential.