Disclosed herein are a system, method and non-transitory program storage device that are intended to provide a control system with quick response for a multi-level power converter. The control system may regulate an output voltage of the power converter based on one or more feedback signals. The feedback signals may be generated based on a differential between the output voltage and a reference voltage. The control system may further include one or more feed-forward signals representative of either the output voltage or transients of the output voltage. The control system may further include one or more switches in parallel with the one or more capacitors to selectively enable and/or disable direct feed-forward and capacitive feed-forward responsive to the output voltage at different levels.

A converter for symmetrical reactive power compensation has phase legs whose associated phases of a three-phase AC voltage network can be connected and are interconnected in an insulated star connection. The first phase leg is devoid of sub modules. The second and third phase legs each has a phase module with series-connected bipolar sub modules. A control device controls phase module currents and determines voltages to be set at each phase module. A decoupling unit calculates correction voltages for each phase module as a function of a first connection voltage between the first and second phase legs, a second connection voltage between the second and third phase legs and a first and/or a second control voltage each derived from target currents and the phase module currents of the second or third phase legs. The voltages to be set are derived from the control voltages and correction voltages.

A power electronic voltage transforming apparatus is used in a two-phase to single-phase conversion. The power electronic voltage transforming apparatus is cooperatively used with a three-phase to two-phase transformer to convert the two-phase power output from the three-phase to two-phase transformer into single-phase power. The two-phase to single-phase power electronic voltage transforming apparatus or three-phase to single-phase power electronic voltage transforming apparatus has an input cascade connection structure formed by cascading n converter modules.

Disclosed herein are a system, method and non-transitory program storage device that are intended to provide a control system with quick response for a multi-level power converter. The control system may regulate an output voltage of the power converter based on one or more feedback signals. The feedback signals may be generated based on a differential between the output voltage and a reference voltage. The control system may further include one or more feed-forward signals representative of either the output voltage or transients of the output voltage. The control system may further include one or more switches in parallel with the one or more capacitors to selectively enable and/or disable direct feed-forward and capacitive feed-forward responsive to the output voltage at different levels.

A method for controlling a modular multilevel converter to reduce the lower order harmonics generated by the converter is provided. The method may also reduce the overall switching loss of the converter by switching the switches close to fundamental switching frequencies while still reducing the lower order harmonics that are generated.

A static synchronous compensator configured to be installed in and provide reactive power to a medium voltage electric distribution system. There is a multi-level cascaded H-bridge (CHB) converter in an enclosure, having a nominal operating voltage in the medium voltage range. There is a first electrical bushing connecting the medium voltage electric distribution system to the input of the CHB converter. There is a second electrical bushing connecting ground or floating ground to the output of the CHB converter. There is a cooling system, which circulates the cooling fluid between in the interior of the enclosure to cool the CHB converter. There is a controller to control the converter to output reactive power at a medium voltage level.

A static synchronous compensator device connected between a source and a load of a three-phase power system, comprising: a main feedback line configured to provide a main feedback signal from lines between the source and the load; a mixer configured to mix the main feedback signal with a balance function to generate a balanced signal; a signal controller configured to convert the balanced signal to a controlled signal; a gain circuit configured to multiply the controlled signal by 1 and to perform proportional gain and integral gain (P & I) processing on the controlled signal to generate an intermediate correction signal; and a pulse width modulator configured to apply a pulse width modulation pattern to modulate the voltage source inverter to generate an AC waveform that is applied to the lines between the source and the load.

The present invention provides a power electronic voltage transforming apparatus, which relates to the fields of electrified railway traction power supply technology, the industrial electricity etc. The power electronic voltage transforming apparatus can solve the problems of dynamic control of negative-sequence current, compensation of reactive power and phase separation of traction network, and can also solve the imbalance of voltage and current caused by adding single-phase load in other industrial power applications. The two-phase to single-phase power electronic voltage transforming apparatus or three-phase to single-phase power electronic voltage transforming apparatus has an input cascade connection structure formed by cascading n converter modules.

A method for reducing lower order harmonics of a power converter includes, for each phase leg of the converter: obtaining a voltage reference for the phase leg; for a present sample, obtaining a flux error of the output voltage of the leg; dividing the first sample flux error by a time period to obtain an average voltage error over said time period; subtracting an obtained processed average voltage error, based on the average voltage error, from the voltage reference to obtain a modified voltage reference for the phase leg; and providing the modified voltage reference to a modulation unit of the converter for controlling the phase leg.

The present invention relates to a method for controlling a reactive power source in a wind power plant, the method comprising the steps of providing a wind turbine reactive power control signal and providing an active power reference signal, said active power reference signal being a measure of an active power production of the wind power plant. A control signal for the reactive power source is generated by combining the wind turbine reactive power control signal and the active power reference signal in such a way that the control signal for the reactive power source becomes a weighted signal of the wind turbine reactive power control signal. Moreover, the present invention relates to control units and wind power plants suitable for carrying out the present invention.