A thyristor starting device includes: a converter which converts AC power supplied from an AC power source into DC power; a DC reactor which smooths a DC current; an inverter which converts the DC power provided from the converter into AC power, and supplies the AC power to a synchronous machine; a gate pulse generation circuit which generates a gate pulse to be provided to thyristors of the converter and the inverter; a control unit which sets a phase control angle of the gate pulse to be provided to the thyristors of the converter, by controlling a current of the converter such that the DC current flowing into the DC reactor matches a current command value; and an abnormality detection unit which compares a detection value of the DC current with the current command value, and determines an abnormality in the gate pulse based on a comparison result.

A power conversion device that constitutes a converter-inverter unit where a converter to convert AC power to DC power and an inverter to convert DC power obtained by conversion of the converter to AC power are connected in series. A capacitor unit including a capacitor cell to accumulate therein the DC power obtained by conversion of the converter is provided between the converter and the inverter. A first conductor electrically connected to one of electrodes of the capacitor cell and a second conductor electrically connected to the other electrode of the capacitor cell are drawn out from the capacitor unit, and the first conductor is connected directly to positive-side capacitor connection terminals and of the converter and positive-side capacitor connection terminals and of the inverter, and the second conductor is connected directly to negative-side capacitor connection terminals and of the converter and negative-side capacitor connection terminals of the inverter.

An HVDC power increase controller includes a command output unit for outputting a current command value according to a disturbance signal to a main controller; a voltage drop determiner receiving an alternating current (AC) voltage and comparing a level of the AC voltage to a lowest level of a voltage causing a rectification failure; and a power tracking determiner receiving a direct current (DC) power and comparing a level of the DC power to an estimated power level corresponding to the current command value. The command output unit adjusts the current command value according to a comparison result of the voltage drop determiner and the power tracking determiner.

A wind power converter device is provided. The wind power converter device includes grid side converters, generator side converters and a DC bus module. Each of the grid side converters includes grid side outputs electrically coupled to a grid and a first and a second DC inputs. Each two of the neighboring grid side converters are connected in series at the second and the first DC inputs. Each of the generator side converters includes generator side inputs electrically coupled to a generator device and a first and a second DC outputs. Each two of the neighboring generator side converters are coupled in series at the second and the first DC outputs. The DC bus module is electrically coupled between the grid side converters and the generator side converters.

A power converter converts input power into DC power. A first switching element is connected between an output node and a high voltage node of the power converter. A second switching element is connected between the output node and a low voltage node of the power converter. First to third driver circuits have first to third power supply nodes to be supplied with first to third operating voltages based on first to third voltages at the output node, the low voltage node, and the high voltage node, respectively. The first to third driver circuits drive the first to third switching elements based on the first to third voltages, respectively. A rectifier circuit is connected between the power supply nodes of the first and second driver circuits, and supplies a current from the power supply node of the first driver circuit toward the power supply node of the third driver circuit.

An ASD circuit includes an input, solid-state switch rectifier bridge, DC link, and DC link capacitor bank. A pre-charge circuit is coupled between the input and the DC link capacitor bank and includes pre-charge relays operable in an on state that allows the AC power input to power the rectifier bridge during a normal operating state and an off state that allows the AC power input to pre-charge the DC link capacitor bank through a pre-charge resistor of the pre-charge circuit during a pre-charge operating state. A protection relay of a protection circuit is coupled between the pre-charge relays and the DC link capacitor bank, the protection relay operable in an on state that prevents the pre-charge circuit from connecting to the DC link capacitor bank when a capacitor short circuit occurs and an off state that allows the pre-charge circuit to electrically connect to the DC link capacitor bank.

An HVDC power increase controller includes a command output unit for outputting a current command value according to a disturbance signal to a main controller; a voltage drop determiner receiving an alternating current (AC) voltage and comparing a level of the AC voltage to a lowest level of a voltage causing a rectification failure; and a power tracking determiner receiving a direct current (DC) power and comparing a level of the DC power to an estimated power level corresponding to the current command value. The command output unit adjusts the current command value according to a comparison result of the voltage drop determiner and the power tracking determiner.

A high voltage direct current (HVDC) transmission system is provided. The high voltage direct current (HVDC) transmission system includes: a rectifier converting alternating current (AC) power into DC power; an inverter converting the DC power into the AC power; a DC transmission line transmitting, to the inverter, the DC power obtained through conversion by the rectifier; a first active power measurement unit measuring first active power input to the rectifier; a second active power measurement unit measuring second active power output from the inverter; and a first control unit detecting an abnormal voltage state on the DC transmission line based on the first and second active power measured.

A system, including: a plurality of load commutated inverters (LCIs) connected in parallel, wherein each LCI includes: a source bridge for converting an alternating current (AC) voltage to a direct current (DC) voltage, wherein the source bridge includes at least one current switching device; a load bridge for converting the DC voltage from the source bridge to a variable frequency AC voltage; and a DC link coupling the source bridge to the load bridge; wherein each LCI includes a respective current regulator for controlling the at least one current switching device in the source bridge of the LCI to generate a current in the DC link.

In a thyristor control device which converts a first AC voltage to a DC voltage and converts the DC voltage to a second AC voltage to be supplied to a synchronous motor, a DC voltage detector is configured to detect the DC voltage, and is provided with an AC voltage detector configured to detect the second AC voltage and an arithmetic circuit configured to determine the DC voltage on the basis of the second AC voltage detected by the AC voltage detector. As a result, there is no need to separately provide a DV voltage detector, which makes it possible to make the device compact in size and cheap in price.