Abstract: A line current iM(k0) of an M side of a first direct-current transmission line is collected at a moment k0. A line current iM(k0?ts) thereof is collected at k0?ts. At a moment k0, a differential value diM(k0) of a current of the side of the first direct-current transmission line is calculated according to the line current iM(k0) and the line current iM(k0?ts). It is determined whether the differential value diM(k0) of the current meets a protection enabling criteria. If so, direct-current protection for the M side of the first direct-current transmission line is enabled. A line current iM(j) of the M side of the first direct-current transmission line is collected at a moment j. A line current iM(j?ts) thereof is collected at a moment j?ts. A differential value diM(j) of the current of the M side of the first direct-current transmission line at the moment j is calculated according to the line current iM(j) and the line current iM(j?ts).

Abstract: Tools for photograph billpay tagging of a digital image are provided. The digital image may correspond to a portion of text positioned upon a medium. The text may correspond to billpay information. The tool may define a graphical reference frame for the digital image. The tool may identify a set of glyphs within the text. The tool may translate a portion of the digital image into an estimated group of characters. The translated portion of the digital image may correspond to at least a part of the set of glyphs. The tool may tag the portion of the digital image with a tag. The tag may be coupled with a billpay input field. The billpay input field may be populated. The billpay input field may be populated with the group of estimated characters. The bill input field may be populated based on the coupling.