Abstract: A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

Abstract: Compact dynamic Phase Angle Regulators (CD-PARs) are provided. A Compact Dynamic Phase Angle Regulator (CD-PAR) is a stand-alone device that regulates phase angle through a single transformer. A CD-PAR has no external energy source, uses low-rating devices, and can be isolated from a fault in the grid. A CD-PAR may be implemented in a single-phase or in a three-phase configuration, but the operation of a CD-PAR cross-couples all three phases. A CD-PAR controls both the real and the reactive power flow between two AC sources having the same frequency by inserting a voltage with controllable magnitude and phase. A CD-PAR may be implemented in either a buck configuration or a boost configuration.

Abstract: Multi-level rectifiers are provided. A multi-level rectifier may convert a medium AC voltage to a medium DC voltage. A multi-level rectifier may comprise an input inductor, a set of diodes, a set of switches, and a DC link comprising a set of capacitors. One end of the input inductor is coupled to the input AC voltage and the other end of the input inductor is coupled to a pair of diodes that are series connected. The set of switches may be regulated such that the inductor may be coupled to a DC voltage point of the DC link. A multi-level rectifier may operate under a set of operation modes. Each operation mode may be determined from the input voltage and the inductor current. Accordingly, a sinusoidal voltage at the fundamental frequency of the input voltage may be synthesized by selectively switching between adjacent operation modes of the set of operation modes.

Abstract: Systems and methods for harmonic resonance control are described. In some embodiments, a system comprises a first switch-controlled VAR source and a harmonic management block which may each be configured to be coupled to a distribution power network. The first switch-controlled VAR source may comprise a first processor, a voltage compensation component, and a switch. The first processor may be configured to enable the voltage compensation component after a delay by controlling the switch based on first proximate voltage after a duration associated with the delay to adjust voltage volt-ampere reactive. The harmonic management block may be configured to compare a second proximate voltage to at least one resonant threshold to detect potential resonance caused by enablement of the voltage compensation component and to engage based on the comparison the resonance compensation component to manage the potential resonance.

Abstract: Methods and systems of field upgradeable transformers are provided. Voltage transformation, intelligence, communications, and control are integrated in a flexible and cost effective manner. A field upgradeable transformer may comprise a transformer module and a cold plate. The transformer module provides voltage transformation. The transformer module is enclosed in a housing containing coolant with dielectric properties, such as mineral oil. The cold plate may be mounted to the housing and thermally coupled to the coolant. Interfaces to the primary side and/or secondary side of transformer module may be configured to be disposed on the surface of the housing. A field upgradable transformer may comprise various electronic modules that are configured to be mounted to the cold plate. An electronic module may be thermally coupled to the coolant, and may be configured to be coupled to the transformer module.

Abstract: Active AC snubbers for AC/AC converters are provided. The active snubbers are actively-controlled AC snubbers that may be used in AC/AC power converters including direct AC converters. The active snubbers provide a free-wheeling path for AC/AC converters, ensuring that the converters are tolerant of errors in measurements and timings and of faults. The desired safe commutation of the switching devices when accurate measurements of voltage and current polarities become difficult or under fault contingencies when trapped energy needs to be dispatched safely is ensured. In addition, the active AC snubber may provide equal voltage sharing among the series-connected devices and clamp output voltages.

Abstract: Systems and methods for an edge of network voltage control of a power grid are described. A system includes a distribution power network, a plurality of loads (at or near an edge of the distribution power network), and a plurality of shunt-connected, switch-controlled volt ampere reactive (VAR) sources also located at the edge or near the edge of the distribution power network where they may each detect a proximate voltage. The VAR source can determine whether to enable a VAR compensation component therein based on the proximate voltage and adjust network VAR by controlling a switch to enable the VAR compensation component. Further still, each of the VAR sources may be integrated within a customer-located asset, such as a smart meter, and a multitude of such VAR sources can be used to effectuate a distributed controllable VAR source (DCVS) cloud network.

Abstract: Systems and methods for switch-controlled VAR sources coupled to a power grid are described. In some embodiments, a system comprises a distribution power network coupled to a first switch-controlled VAR source. The first switch-controlled VAR source may comprise a processor, a voltage compensation component, and a switch. The first switch-controlled VAR source may be configured to obtain a first delay value, monitor a first proximate voltage, initiate a first delay duration based on the comparison of the first proximate voltage to at least one set point, the first delay duration being based on the first delay value, determine, with the processor, after the first delay duration, whether to connect the voltage compensation component based on the monitored voltage, and control, based on the determination, the switch to connect the voltage compensation component to adjust a network voltage or a network voltage component.

Abstract: Isolated Dynamic-Current (“Dyna-C”) converters are converters that convert incoming 3-phase AC or DC power to a mix of DC and AC power via an isolation link. In various embodiments, the isolation link is a high-frequency isolation transformer. Isolated Dyna-C converters may provide a high-frequency galvanic isolation and are able to convert three-phase AC power to three-phase AC power, or three-phase AC power to DC and vice versa. The topology is minimal and the costs are low. Isolated Dyna-C converters provide fast current responses and keep the losses low by using a simplified two-stage conversion and providing a magnetizing current that is dynamically controllable and tailored to the load. An isolated Dyna-C converter may synthesize currents at its input or output ports with an arbitrary phase that is relative to the grid or load voltages, thereby enabling a full independent control over the active and reactive power at its ports.

Abstract: Dynamic power flow controllers are provided. A dynamic power flow controller may comprise a transformer and a power converter. The power converter is subject to low voltage stresses and not floated at line voltage. In addition, the power converter is rated at a fraction of the total power controlled. A dynamic power flow controller controls both the real and the reactive power flow between two AC sources having the same frequency. A dynamic power flow controller inserts a voltage with controllable magnitude and phase between two AC sources; thereby effecting control of active and reactive power flows between two AC sources.

Abstract: Multi-level rectifiers are provided. A multi-level rectifier may convert a medium AC voltage to a medium DC voltage. A multi-level rectifier may comprise an input inductor, a set of diodes, a set of switches, and a DC link comprising a set of capacitors. One end of the input inductor is coupled to the input AC voltage and the other end of the input inductor is coupled to a pair of diodes that are series connected. The set of switches may be regulated such that the inductor may be coupled to a DC voltage point of the DC link. A multi-level rectifier may operate under a set of operation modes. Each operation mode may be determined from the input voltage and the inductor current. Accordingly, a sinusoidal voltage at the fundamental frequency of the input voltage may be synthesized by selectively switching between adjacent operation modes of the set of operation modes.

Abstract: Methods and systems of network voltage regulating transformers are provided. A network voltage regulating transformer (NVRT) may provide voltage transformation, isolation, and regulation. A NVRT may further provide power factor corrections. Multiple NVRTs may operate autonomously and collectively thereby achieving an edge of network voltage control when installed to a power system. A NVRT comprises a transformer, a VAR source, and a control module. The input current (i.e., the current through the primary side of the transformer), the output current (i.e., the current through the secondary side of the transformer), and/or the output voltage (i.e., the voltage across the secondary side of the transformer) may be monitored.

Abstract: A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

Abstract: Active AC snubbers for AC/AC converters are provided. The active snubbers are actively-controlled AC snubbers that may be used in AC/AC power converters including direct AC converters. The active snubbers provide a free-wheeling path for AC/AC converters, ensuring that the converters are tolerant of errors in measurements and timings and of faults. The desired safe commutation of the switching devices when accurate measurements of voltage and current polarities become difficult or under fault contingencies when trapped energy needs to be dispatched safely is ensured. In addition, the active AC snubber may provide equal voltage sharing among the series-connected devices and clamp output voltages.

Abstract: Systems and methods for dynamic AC line voltage regulation are provided. A simple and cost-effective method for achieving AC line voltage regulation in AC systems including split-phase systems, of which the voltage for each voltage line may be regulated over a specified range, is provided. Buck and boost regulation is achieved for lowering or increasing the line voltage, respectively, with reference to the incoming grid voltage. Systems for dynamic AC line voltage regulation may comprise an AC/AC converter which uses fractionally rated switches and magnetics that handle only a fraction of the load current, resulting in lower costs. The use of an AC snubber further provides safe and robust switching of the main switching devices by eliminating failure prone switching sequences that are dependent on accurate assessment of voltage and/or current polarity for AC or bi-directional switches.

Abstract: Power flow controllers based on Imputed DC Link (IDCL) cells are provided. The IDCL cell is a self-contained power electronic building block (PEBB). The IDCL cell may be stacked in series and parallel to achieve power flow control at higher voltage and current levels. Each IDCL cell may comprise a gate drive, a voltage sharing module, and a thermal management component in order to facilitate easy integration of the cell into a variety of applications. By providing direct AC conversion, the IDCL cell based AC/AC converters reduce device count, eliminate the use of electrolytic capacitors that have life and reliability issues, and improve system efficiency compared with similarly rated back-to-back inverter system.

Abstract: Isolated Dynamic-Current (“Dyna-C”) converters are converters that convert incoming 3-phase AC or DC power to a mix of DC and AC power via an isolation link. In various embodiments, the isolation link is a high-frequency isolation transformer. Isolated Dyna-C converters may provide a high-frequency galvanic isolation and are able to convert three-phase AC power to three-phase AC power, or three-phase AC power to DC and vice versa. The topology is minimal and the costs are low. Isolated Dyna-C converters provide fast current responses and keep the losses low by using a simplified two-stage conversion and providing a magnetizing current that is dynamically controllable and tailored to the load. An isolated Dyna-C converter may synthesize currents at its input or output ports with an arbitrary phase that is relative to the grid or load voltages, thereby enabling a full independent control over the active and reactive power at its ports.

Abstract: Compact dynamic Phase Angle Regulators (CD-PARs) are provided. A Compact Dynamic Phase Angle Regulator (CD-PAR) is a stand-alone device that regulates phase angle through a single transformer. A CD-PAR has no external energy source, uses low-rating devices, and can be isolated from a fault in the grid. A CD-PAR may be implemented in a single-phase or in a three-phase configuration, but the operation of a CD-PAR cross-couples all three phases. A CD-PAR controls both the real and the reactive power flow between two AC sources having the same frequency by inserting a voltage with controllable magnitude and phase. A CD-PAR may be implemented in either a buck configuration or a boost configuration.

Abstract: An area electric power system includes a number of direct current power sources, and a number of inverters operatively associated with the number of direct current power sources. Each of the number of inverters is structured to provide real power and controlled reactive power injection to detect islanding. An output is powered by the number of inverters. A number of electrical switching apparatus are structured to electrically connect the number of inverters to and electrically disconnect the number of inverters from a utility grid. A number of devices are structured to detect islanding with respect to the utility grid responsive to a number of changes of alternating current frequency or voltage of the output.

Abstract: A power conversion system includes a number of photovoltaic arrays, a number of inverters, a transformer, and processor. The processor is structured to control the number of inverters and operate the power conversion system to provide maximum efficiency of power conversion by the number of photovoltaic arrays, the number of inverters and the transformer, and to maximize power output from the number of photovoltaic arrays.