There is provided a transformer system (10) for converting a grid voltage (V.sub.grid) to a regulated voltage (V.sub.regulated) and output the regulated voltage (V.sub.regulated) to a power line (30), the transformer system (10) comprising: a first transformer (40) configured to step down the grid voltage (V.sub.grid) to an unregulated voltage (V.sub.unregulated) and provide the unregulated voltage (V.sub.unregulated) at an output of the first transformer (40); a shunt coupling transformer (50) connected in parallel with the output of the first transformer (40) and further connected to power electronics circuitry (60); and a series coupling transformer (70) connected in series with the output of the first transformer (40) and further connected to the power electronics circuitry (60). The power electronics circuitry (60) adds, via the series coupling transformer, a conditioning voltage (V.sub.conditioning) in series to the unregulated voltage (V.sub.unregulated) to generate the regulated voltage (V.sub.regulated). The first transformer, the series coupling transformer and the shunt coupling transformer are housed in a single transformer tank (80), and the power electronics circuitry is housed in a power electronics enclosure (90) separate from the transformer tank. Each of the transformer tank and the power electronics enclosure comprises one or more openings (95) through which electrical connections (97) between the shunt coupling transformer (50), the series coupling transformer (70) and the power electronics circuitry (60) pass.

There is provided a transformer system (10) for converting a grid voltage (V.sub.grid) to a regulated voltage (V.sub.regulated) and output the regulated voltage (V.sub.regulated) to a power line (30), the transformer system (10) comprising: a first transformer (40) configured to step down the grid voltage (V.sub.grid) to an unregulated voltage (V.sub.unregulated) and provide the unregulated voltage (V.sub.unregulated) at an output of the first transformer (40); a shunt coupling transformer (50) connected in parallel with the output of the first transformer (40) and further connected to power electronics circuitry (60); and a series coupling transformer (70) connected in series with the output of the first transformer (40) and further connected to the power electronics circuitry (60). The power electronics circuitry (60) adds, via the series coupling transformer, a conditioning voltage (V.sub.conditioning) in series to the unregulated voltage (V.sub.unregulated) to generate the regulated voltage (V.sub.regulated). The first transformer, the series coupling transformer and the shunt coupling transformer are housed in a single transformer tank (80), and the power electronics circuitry is housed in a power electronics enclosure (90) separate from the transformer tank. Each of the transformer tank and the power electronics enclosure comprises one or more openings (95) through which electrical connections (97) between the shunt coupling transformer (50), the series coupling transformer (70) and the power electronics circuitry (60) pass.

A zero-sequence blocking transformer includes a first core part, a first pair of windings wound around the first core part, a second core part and a second pair of windings wound around the second core part, the first core and the second core having a geometry to generate a leakage inductance.

An electrical power distribution network includes: a plurality of electrical power control apparatuses, each of which include one or more signal conversion components receiving electrical power in the form of a first signal and generating a corresponding second signal, a controller that controls operation of the signal conversion components, electrical power generation components acting as sources of electrical power to at least some of the electrical power control apparatuses, and electrical power consumption components acting as sinks of electrical power from at least some of the electrical power control apparatuses. The electrical power control apparatuses operate autonomously but are interconnected so that the electrical power control apparatuses collectively maintain the voltages and frequencies of electrical power signals flowing through the electrical power distribution network at target values to compensate for variations in the sinks and/or sources of electrical power.

An electrical power distribution network includes: a plurality of electrical power control apparatuses, each of which include one or more signal conversion components receiving electrical power in the form of a first signal and generating a corresponding second signal, a controller that controls operation of the signal conversion components, electrical power generation components acting as sources of electrical power to at least some of the electrical power control apparatuses, and electrical power consumption components acting as sinks of electrical power from at least some of the electrical power control apparatuses. The electrical power control apparatuses operate autonomously but are interconnected so that the electrical power control apparatuses collectively maintain the voltages and frequencies of electrical power signals flowing through the electrical power distribution network at target values to compensate for variations in the sinks and/or sources of electrical power.

A higher-level control unit 5 generates a level command L* on the basis of a command value cmd. A switching load distribution control unit 6 stores the output period information of each cell and designates a gate signal so that: in case of a pattern by which a cell is changed from ±1 level to 0 level, the cell having the longest ±1 level period information is set to 0 level; and in case of a pattern by which a cell is changed from 0 level to ±1 level, the cell having the longest 0 level output period is set to ±1 level. This distributes the switching load of each cell in the serial multiplex inverter control device.

A frequency conversion power transmission system includes: a new energy power generation base, a first isolation device, a second isolation device, an alternating current-alternating current (AC-AC) frequency conversion device and a power transmission cable; the new energy power generation base is configured to supply electrical energy to an AC power grid, and operate at a constant voltage and a constant or variable frequency according to environmental conditions including weather, an environment or a distance; the first isolation device is connected to the new energy power generation base; the second isolation device is connected to the AC power grid; an input terminal of the AC-AC frequency conversion device is connected to the first isolation device, an output terminal of the AC-AC frequency conversion device is connected to the second isolation device, and the power transmission cable is configured to connect the new energy power generation base and the first isolation device.

A current sampling system, the system including a magnetic component, that is an inductor or a transformer that has at least one winding, where the at least one winding has a first part and a second part, where a first terminal of the first part is connected to a first terminal of the second part, and where a second terminal of the first part is separated from a second terminal of the second part, and a current detection circuit, where the second terminal of the second part is connected to the current detection circuit, and where the current detection circuit is configured to sample a current flowing through the second part, and obtain a total current of the winding based on the sampled current flowing through the second part and a preset ratio.

An electric power conversion circuit includes: a first leg including first and third switches; a second leg including second and fourth switches; a third leg including fifth and seventh switches; a fourth leg including sixth and eighth switches; a first reactor connected between a first node, in which the first and second legs are connected to each other, and a fifth node, in which the third and fourth legs are connected to each other; a second reactor connected between a second node to which the first and second legs are connected and a sixth node to which the third and fourth legs are connected; a first port terminal connected to the first node; a second port terminal connected to the sixth node; a third port terminal connected to a midpoint of each of the first and third legs; and a fourth port terminal connected to a midpoint of each of the second and fourth legs.

An electronic brushless variable transformer. Variable autotransformers, use brushes, and as such, have moving parts requiring maintenance and periodic cleaning of the brushes. A variable transformer without brushes is advantageous in that it eliminates the cleaning and maintenance of brushes.