A voltage transform part transforms the direct-current power input to an input part. A first input and output part outputs the transformed direct-current power to a battery unit and to which direct-current power is input from the battery unit. A conversion part converts the direct-current power input to the input part into alternating-current power. A second input and output part outputs the alternating-current power to a power system or a load and to which an alternating-current power is input from the power system. The conversion part converts the alternating-current power input to the second input and output part into direct-current power. The second voltage transform part transforms the direct-current power converted by the conversion part and transforms the direct-current power input to the first input and output part. The conversion part converts the direct-current power transformed by the second voltage transform part into alternating-current power.

In the field of high voltage direct current (HVDC) power transmission networks, there is a need for improvements to allow a single power converter to control individual AC network voltages carried by multiple AC transmission conduits to multiple AC network elements, such as respective wind parks.

Provided are a control unit having a first control state in which a first switching element and a second switching element of one series circuit are turned on and a second control state to which the first control state shifts and in which a first switching element of another series circuit and the second switching element of the one series circuit are turned on, and executing control so as to apply predetermined voltage to the other side of a transformer during a predetermined time period during the first control state before shifting to the second control state.

A protection device for a power converter provided between an AC system and a DC power transmission system is configured to: receive an input of an AC current value obtained between a transformer connected to the AC system and the power converter capable of converting AC power into DC power; receive an input of a change rate of a direct current detected by a Rogowski coil provided between a DC line and the power converter, the DC line receiving DC power from the power converter; determine based on the AC current value and the change rate whether a fault occurs or not in one of the power converter and the DC line; and output information for protecting the power converter based on a determination result.

A power supply device is provided. The power supply device includes a rectifier circuit for rectifying an inputted alternating current power supply, a capacitor circuit comprising a first and second capacitor which are connected in series, and smoothing the alternating current power supply rectified in the rectifier circuit, an inverter for converting the output power of the capacitor circuit to a preset power and outputting same, a switch for selectively connecting a middle node of the first capacitor and the second capacitor and an end of the alternating current power, a sensor for detecting a size of the alternating current power, and a controller which confirms a power mode of the alternating current power on the basis of an output value of the sensor, and which controls the switch so that the capacitor circuit multiplies and amplifies the selectively rectified alternating current power based on the confirmed power mode.

A power supply device is provided. The power supply device includes a rectifier circuit for rectifying an inputted alternating current power supply, a capacitor circuit comprising a first and second capacitor which are connected in series, and smoothing the alternating current power supply rectified in the rectifier circuit, an inverter for converting the output power of the capacitor circuit to a preset power and outputting same, a switch for selectively connecting a middle node of the first capacitor and the second capacitor and an end of the alternating current power, a sensor for detecting a size of the alternating current power, and a controller which confirms a power mode of the alternating current power on the basis of an output value of the sensor, and which controls the switch so that the capacitor circuit multiplies and amplifies the selectively rectified alternating current power based on the confirmed power mode.

The invention relates to a system for generating electric power, comprising: an alternator (1) for coupling with a drive system (7), supplying an AC voltage to an output bus (10); a reversible AC/DC converter (2) in which the AC bus (6) is connected to the output bus (10) of the alternator (1); an electricity-storage element (3) connected to the DC bus (9) of the converter (2); a controller (4) arranged to react to a transient state of load-shedding or charging impact by controlling the converter (2) so as to collect energy on the output bus (10) of the alternator (2) and to store same in the storage element (3) in the case of load-shedding, and to collect energy in the storage element (3) and to inject same into the output bus (10) in the case of charging impact, the converter (2) being controlled so as to inject currents to compensate for harmonic currents into the AC bus (10) of the alternator (1).

The invention relates to a system for generating electric power, comprising: an alternator (1) for coupling with a drive system (7), supplying an AC voltage to an output bus (10); a reversible AC/DC converter (2) in which the AC bus (6) is connected to the output bus (10) of the alternator (1); an electricity-storage element (3) connected to the DC bus (9) of the converter (2); a controller (4) arranged to react to a transient state of load-shedding or charging impact by controlling the converter (2) so as to collect energy on the output bus (10) of the alternator (2) and to store same in the storage element (3) in the case of load-shedding, and to collect energy in the storage element (3) and to inject same into the output bus (10) in the case of charging impact, the converter (2) being controlled so as to inject currents to compensate for harmonic currents into the AC bus (10) of the alternator (1).

In the field of high voltage direct current power transmission networks, a method of controlling a converter that includes at least one converter limb which corresponds to a respective phase of the converter, is described. The method includes obtaining a respective AC current demand phase waveform for each converter limb which the corresponding converter limb is required to track, and a DC current demand which each converter limb is also required to track. The method further determining a limb portion current for each limb portion that the limb portion must contribute to track the corresponding required AC current demand phase waveform and the required DC current demand, and providing a limb portion voltage source for each limb portion to achieve the corresponding limb portion current. The method carrying out mathematical optimization to determine one or more optimal limb portion currents and/or provide optimal limb portion voltage sources.

In the field of high voltage direct current power transmission networks, a method of controlling a converter that includes at least one converter limb which corresponds to a respective phase of the converter, is described. The method includes obtaining a respective AC current demand phase waveform for each converter limb which the corresponding converter limb is required to track, and a DC current demand which each converter limb is also required to track. The method further determining a limb portion current for each limb portion that the limb portion must contribute to track the corresponding required AC current demand phase waveform and the required DC current demand, and providing a limb portion voltage source for each limb portion to achieve the corresponding limb portion current. The method carrying out mathematical optimization to determine one or more optimal limb portion currents and/or provide optimal limb portion voltage sources.