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.

Various examples are provided for isolated voltage optimization and control. In one example, a stackable isolated voltage optimization module (SIVOM) includes a transformer having a turns ratio between a primary winding and a secondary winding; a switching circuit configured to energize the secondary winding with a voltage provided from the three-phase power system or short the secondary winding; and a connection block configured to couple the switching circuitry to the first phase and a neutral, or to second and third phases of the three-phase power system. In another example, a system includes a SIVOM coupled to each phase of a three-phase power system, where each SIVOM comprises: a transformer and a switching circuit configured to boost or buck a voltage or change a phase angle of the phase coupled to that SIVOM by energizing a secondary winding of the transformer with a voltage provided from the three-phase power system.

Various examples are provided for isolated voltage optimization and control. In one example, a stackable isolated voltage optimization module (SIVOM) includes a transformer having a turns ratio between a primary winding and a secondary winding; a switching circuit configured to energize the secondary winding with a voltage provided from the three-phase power system or short the secondary winding; and a connection block configured to couple the switching circuitry to the first phase and a neutral, or to second and third phases of the three-phase power system. In another example, a system includes a SIVOM coupled to each phase of a three-phase power system, where each SIVOM comprises: a transformer and a switching circuit configured to boost or buck a voltage or change a phase angle of the phase coupled to that SIVOM by energizing a secondary winding of the transformer with a voltage provided from the three-phase power system.

A three-phase transformer, and method of assembling the same, are disclosed. The three-phase transformer comprises three closed-loop magnetic core elements each comprising two pairs of partial primary and secondary coils respectively associated with two different electrical phases of the three-phase transformer. Each pair of partial primary and secondary coils is placed over a same magnetic core section of its closed-loop magnetic core element and its partial primary and secondary coils are respectively electrically connected either in series or in parallel to partial primary and secondary coils of another pair of partial primary and secondary coils associated with the same electrical phase and placed over another one of the closed-loop magnetic core elements. The serially or parallelly electrically connected partial primary coils are electrically coupled for connection to a three-phase electric power supply. The serially or parallely electrically connected secondary coils are electrically coupled for connection to a three-phase load.

A current regulator for regulating alternating current (AC) flow to a load device is provided. The current regulator can include an AC coupling device that can be electrically connected to the load device via an output electrical path, a current control device electrically connected in series with the AC coupling device, and an AC feedback circuit electrically connected to the output electrical path and the current control device. The current control device can modify a current flow through at least one component of the AC coupling device in response to receiving an error correction current. An output AC current provided to the load device can be controlled based on the current flow through the component of the AC coupling device. The AC feedback circuit can include voltage error compensation device that provides the error correction current in response to receiving a feedback voltage corresponding to the output AC current.

A current regulator for regulating alternating current (AC) flow to a load device is provided. The current regulator can include an AC coupling device that can be electrically connected to the load device via an output electrical path, a current control device electrically connected in series with the AC coupling device, and an AC feedback circuit electrically connected to the output electrical path and the current control device. The current control device can modify a current flow through at least one component of the AC coupling device in response to receiving an error correction current. An output AC current provided to the load device can be controlled based on the current flow through the component of the AC coupling device. The AC feedback circuit can include voltage error compensation device that provides the error correction current in response to receiving a feedback voltage corresponding to the output AC current.

A system, in one embodiment, includes a voltage fault detection system. The voltage fault detection system may be configured to acquire a reference voltage signal from a power line to determine if a voltage sag condition is present in the power line, determine a correction voltage for correcting the voltage sag condition, use the reference voltage to produce the correction voltage, and apply the correction voltage to the power line.

A system, in one embodiment, includes a voltage fault detection system. The voltage fault detection system may be configured to acquire a reference voltage signal from a power line to determine if a voltage sag condition is present in the power line, determine a correction voltage for correcting the voltage sag condition, use the reference voltage to produce the correction voltage, and apply the correction voltage to the power line.