Abstract: A power converter is provided. The power converter includes at least one leg. The at least one leg of the power converter includes a plurality of switching units. The switching units are coupled with each other in a serial fashion. Further, in the power converter, the switching units are selected such that at least two switching units in the power converter have different operating voltages.

Abstract: A method and a high-voltage DC (HVDC) power system are provided. The system includes a plurality of sending-end (SE) modules coupled in electrical series and divided into at least two groups that each operate independently with respect to an electrical ground and a plurality of receiving-end (RE) power converter modules electrically coupled to the plurality of SE modules, the plurality of RE power converter modules including a fast ground-fault detection and control device, the plurality of RE power converter modules including a receiving-end front-end DC-DC converter controller, and an output current damping control.

Abstract: A photovoltaic (PV) control system generates a power output rate control signal based on a monitored rate of change of collective power output generated via a plurality of PV subsystems and a desired collective output power change rate for the plurality of PV subsystems and communicates the power output rate control signal to the plurality of PV subsystems to control a rate of change of one or more operating parameters of individual PV subsystems in order to control a rate of change of collective output power of the plurality of solar PV subsystems.

Abstract: A power converter module is provided. The power converter module includes a first converter leg and a second converter leg. The first converter leg includes a first switching unit and a second switching unit coupled in series. The second switching unit is disposed in a reverse orientation with respect to an orientation of the first switching unit. The second converter leg includes a third switching unit and a diode coupled in series. The third switching unit is disposed in a reverse orientation with respect to the orientation of the first switching unit. The power converter also includes a first energy storage device operatively coupled between the first converter leg and the second converter leg. The power converter module further includes a second energy storage device operatively coupled between the first converter leg and the second converter leg.

Abstract: A multilevel converter includes at least one phase. Each phase of the multilevel converter includes a direct current (DC) link, a first circuit, a second circuit, and a phase capacitor. The DC link includes a first capacitor, a second capacitor, and a third capacitor situated between the first and second capacitors. The first circuit is electrically coupled to two terminals of the first capacitor. The second circuit is electrically coupled to two terminals of the second capacitor. The phase capacitor is electrically coupled between the first circuit and the second circuit.

Abstract: A high voltage direct current (HVDC) converter system includes a line commutated converter (LCC) configured to convert a plurality of AC voltages and currents to a regulated DC voltage of one of positive and negative polarity and a DC current transmitted in only one direction. The HVDC converter system also includes a buck converter configured to convert a plurality of AC voltages and currents to a regulated DC voltage of one of positive and negative polarity and a DC current transmitted in one of two directions. The LCC and the buck converter are coupled in parallel to an AC conduit and are coupled in series to a DC conduit. The HVDC converter system further includes a filtering device coupled in parallel to the buck converter through the AC conduit. The filtering device is configured to inject AC current having at least one harmonic frequency into the AC conduit.

Abstract: A power conversion system includes a first converter effectively connected in series to a second converter. Each converter has a plurality of output levels. A phase-shifted transformer is coupled to the converters. The phase-shifted transformer has a delta-wound winding and an open star winding. The first converter is coupled to the open star winding and the second converter is coupled to the delta winding. The open star winding is configured for direct connection to either of a load or the open star winding of a second phase-shifted transformer, having a delta winding connected to a third converter. One or more DC voltage sources are each connected to the first and second converters by a respective DC link capacitor. Each DC voltage source is connected to a common power grid by an isolated multiphase transformer winding.

Abstract: A load commutated inverter (LCI) drive system for a synchronous electrical machine is provided. The system may include a first supply bridge and a second supply bridge, each of which may include an alternating current to direct current (AC-to-DC) source side converter, a DC link circuit, and a DC-to-AC load side inverter. The system may include a controller for selectively controlling at least one of the first supply bridge and the second supply bridge by selective firings of SCRs. The electrical power outputted from the first supply bridge and the second supply bridge may be combined by an output delta-wye electric power transformer and supplied to the electrical machine. The LCI drive system may further include one or more input electric power transformers configured to supply an input electric power to the first supply bridge and the second supply bridge.

Abstract: A multilevel converter includes at least one phase each including several cascaded basic units each including a first switching element, a second switching element, and a separate and electrically isolated DC source (SDCS). The SDCS is electrically coupled between the first switching element and the second switching element in each basic unit. Each of the adjacent pairs of the basic units are electrically crosswise coupled together by electrical coupling of the first switching element of a first basic unit of the two adjacent basic units to the second switching element of a second basic unit of the two adjacent basic units, and electrically coupling the second switching element of the first basic unit to the first switching element of the second basic unit.

Abstract: A power transmission system includes a first unit for carrying out the steps of receiving high voltage direct current (HVDC) power from an HVDC power line, generating an alternating current (AC) component indicative of a status of the first unit, and adding the AC component to the HVDC power line. Further, the power transmission system includes a second unit for carrying out the steps of generating a direct current (DC) voltage to transfer the HVDC power on the HVDC power line, wherein the HVDC power line is coupled between the first unit and the second unit, detecting a presence or an absence of the added AC component in the HVDC power line, and determining the status of the first unit based on the added AC component.

Abstract: Systems and methods for controlling an electrical power supply are provided. One system includes an input configured for receiving voltage measurement signals for the power supply and a controller for one or more electrical phases of the power supply. The controller includes an integrator configured to integrate the received voltage measurement signals and to generate integrated control signals or integrated error signals. The controller is configured to generate an output signal using the integrated control signals or the integrated error signals. The system also includes an output configured to output the output signal to control switching of the power supply.

Abstract: A power converter is provided. The power converter includes a converter leg including switches for converting power. The power converter also includes a controller for switching the switches using a pulse width modulation technique. The power converter further includes an interface inductor coupled to the converter leg for avoiding a reverse recovery of current in the switches during operation.

Abstract: A power converter is presented. The power converter includes at least one leg, the at least one leg includes a first string, where the first string includes a plurality of controllable semiconductor switches, a first connecting node, and a second connecting node, and where the first string is operatively coupled across a first bus and a second bus. Furthermore, the at least one leg includes a second string operatively coupled to the first string via the first connecting node and the second connecting node, where the second string includes a plurality of switching units. A method for power conversion is also presented.

Abstract: A power converter includes at least one leg with a first string including a plurality of controllable semiconductor switches, a first connecting node, and a second connecting node, wherein the first string is operatively coupled across a first bus and a second bus. The at least one leg also includes a second string operatively coupled to the first string via the first connecting node and the second connecting node, wherein the second string includes a plurality of switching units. The first string includes a first branch and a second branch, wherein the second branch is operatively coupled to the first branch via a third connecting node and the third connecting node is coupled to a ground connection.

Abstract: The present subject matter is directed to systems and methods for interfacing variable speed generators to a power distribution grid. A plurality of doubly-fed induction generators (DFIG) are provided and coupled to a common shaft of a prime mover. Each of the plurality of DFIGs provides an electrical power output having an output frequency based on a rotational speed of the common shaft. A converter coupled to each DFIG provides variable excitation signals to its respective DFIG sufficient to adjust its output frequency to conform to a power grid frequency requirement.

Abstract: An AC-AC Converter for an AC source which in one embodiment has a first rectifier section rectifying the AC source into a first pulsed DC link voltage signal and a high frequency modulating section coupled to the first pulsed DC link voltage signal and producing a high frequency AC voltage signal. A high frequency transformer is coupled to the high frequency AC voltage signal producing a transformed high frequency AC signal. There is a second rectifier section coupled to the transformed high frequency AC signal and producing a second pulsed DC voltage signal and an unfolder section coupled to the second pulsed DC voltage signal and producing an output AC signal.

Abstract: A power transmission system is provided. The power transmission system includes a power source for providing power. The system also includes a power conversion system comprising power converters coupled to receive the power and convert the power to DC power, wherein the power conversion system comprises a plurality of legs each configured for pulse width modulation. The system further includes a controller comprising an analysis module programmed for determining a number of legs for switching for minimizing a cost function based on operating conditions of the power conversion system. The controller also includes a switch control module programmed for using the number of legs determined by the analysis module for generating switching commands for the power conversion system. The system also includes a DC transmission bus coupled to receive the DC power and transmit the DC power.

Abstract: A multilevel converter includes at least one phase. Each phase of the multilevel converter includes a direct current (DC) link, a first circuit, a second circuit, and a phase capacitor. The DC link includes a first capacitor, a second capacitor, and a third capacitor situated between the first and second capacitors. The first circuit is electrically coupled to two terminals of the first capacitor. The second circuit is electrically coupled to two terminals of the second capacitor. The phase capacitor is electrically coupled between the first circuit and the second circuit.

Abstract: A multilevel converter includes at least one phase each including several cascaded basic units each including a first switching element, a second switching element, and a separate and electrically isolated DC source (SDCS). The SDCS is electrically coupled between the first switching element and the second switching element in each basic unit. Each of the adjacent pairs of the basic units are electrically crosswise coupled together by electrical coupling of the first switching element of a first basic unit of the two adjacent basic units to the second switching element of a second basic unit of the two adjacent basic units, and electrically coupling the second switching element of the first basic unit to the first switching element of the second basic unit.

Abstract: A gradient amplifier system is presented. An embodiment of a gradient amplifier system that includes a power stage having a plurality of bridge amplifiers, where each of the plurality of bridge amplifiers operates at a first switching frequency. The gradient amplifier system further includes a gradient coil coupled to an output terminal of the power stage and configured to produce a magnetic field proportional to a coil current signal supplied by the power stage. In addition, the gradient amplifier system includes a controller stage coupled to an input terminal of the power stage and configured to generate a pulse width modulated gate signal based on the coil current signal and a reference current signal, where the pulse width modulated gate signal is generated at a second switching frequency upon occurrence of a slew rate associated with the reference current signal is below a determined threshold rate and an amplitude level associated with the reference current signal is above a determined level.