Abstract:
A method for controlling a first and a second reverse-conducting insulated gate bipolar transistor (RC-IGBT), electrically connected in series, is disclosed. A collector of the first RC-IGBT is electrically connected to a positive pole of a direct current voltage source, and an emitter of the second RC-IGBT is electrically connected to a negative pole of the DC voltage source. Further, an emitter of the first RC-IGBT is electrically connected to a collector of the second RC-IGBT to form an alternating current terminal. A gate voltage is applied to respective gates of the first and second RC-IGBTs, wherein the gate voltage is controlled based on a magnitude and a direction of an output current on the AC terminal and on a command signal alternating between a first and a second value.
Abstract:
Cells in a phase leg of a multilevel converter are controlled through regulating, using tap-changer control, the modulation index of the converter to above 0.80, providing a group of carrier waves for the phase leg, where these carrier waves are identical but displaced in time from each other with a time delay, providing a voltage reference for the phase leg being separate from voltage references provided for other phase legs, stop switching of the cells when waveform values of a power transmission converter waveform are detected to be in a selected interval around a peak value of the power transmission converter waveform and control switching of the cells based on comparisons of the respective carrier waves with the voltage reference when the waveform values of the power transmission converter waveform are detected to be outside the selected interval.
Abstract:
A wind power converter includes a multiple of phase power converters, each of which being adapted to convert power output from a corresponding phase of a wind generator to a corresponding phase of a grid. Each of the phase power converters includes a full-wave rectifier, being adapted to rectify the power input through a first terminal and a second terminal from the corresponding phase of the wind generator; a capacitor being adapted to be charged by the power rectified by the full-wave rectifier; and a full-wave active inverter, being adapted to invert the power stored in the capacitor and output the inverted power to the corresponding phase of the grid through a third terminal and a fourth terminal. The first terminal or the second terminal is connected to a first virtual neutral; and the third terminal or the fourth terminal is connected to a second virtual neutral. By having such topology, each phase power converter serves as a power conversion module independent of the others. Thus, the electrical coupling between any two of the phase power converter is removed. The details of the phase power converter will be described thereafter. It is therefore an objective of the invention to decrease the cost and at the same increase the feeding electrical power quality.
Abstract:
A method and computer program product are provided for selecting switching cells for voltage contribution in a phase arm of a multilevel converter, a cell selecting control device for a multilevel converter and a multilevel converter. The cell selecting control device and multilevel converter includes a balancing control element that obtains a reference voltage for the phase arm, obtains a measurement of the current running through the phase arm and selects cells for contributing to an AC voltage output from the multilevel converter based on the reference voltage and the magnitude of the phase arm current.
Abstract:
A method and a device for diagnosing the status of an electrical apparatus having a sealed fluid based insulating system. The device includes at least one input for receiving measurements of a current running through the apparatus and measurements of an actual apparatus fluid pressure as well as a diagnosing unit. The diagnosing unit determines a corresponding theoretical apparatus fluid pressure based on the measured current, compares the actual apparatus fluid pressure with the theoretical apparatus fluid pressure and diagnoses the status of the apparatus based on the comparison.
Abstract:
A control system may include a plurality of terminal boards. Each of the plurality of terminal boards may at least include a power pin. The definition of the power pin on at least one of the plurality of terminal boards may be different from the definition of the power pin on another one of the plurality of terminal boards. Thus, if the at least one of the plurality of terminal boards is connected to a wrong input/output module, the input/output module will not get a process power supplied via the power pin on the terminal board. Therefore, a wrong input/output signal will not be transferred, and the input/output module will not be damaged even if a higher process voltage is provided by a wrong terminal board.
Abstract:
A mechanical switch in the form of a bypass switch assembly is arranged between two electrical conductors (busbars) and stays open during normal operation. When a cell fault happens, the fault and bypass information is transmitted to an actuator (acting as a trigger circuit) which activates inter alia a gas generator producing huge volume of gas in a very short time. The gas pressure pushes a movable member to bridge the two electrical conductors with ultrafast speed.
Abstract:
A device for indicating the state of an electrical switching apparatus includes a movable contact arranged movable between a first and a second position. The device includes at least one protruding contact element arranged on the movable contact, at least one contact pin arranged in the close vicinity to the movable contact such that said contact element abuts the contact pin when the movable contact is in the first position and said contact element is at a distance from the contact pin when the movable contact is in the second position. The contact element and the contact pin form an electrical switch and a detector arrangement configured to detect when said electrical switch is closed and by that detect when the movable contact is in the first position.