A high voltage direct current (HVDC) transmission system comprises a first terminal comprising a first voltage source converter (VSC) having a first and second VSC terminals and a first line commutated converter (LCC) having first and second LCC terminals; a second terminal comprising a second VSC having third and fourth VSC terminals and a second LCC having third and fourth LCC terminals; and a transmission line pair comprising a positive transmission line that couples the first VSC terminal and the first LCC terminal of the first VSC and the first LCC, respectively, to the third VSC terminal and the third LCC terminal of the second VSC and the second LCC, respectively, and a second positive line that couples the second VSC terminal and the second LCC terminal of the first VSC and the first LCC, respectively, to the fourth VSC terminal and the fourth LCC terminal of the second VSC and the second LCC, respectively.

The disclosure discloses a commutation failure prediction method, device and storage medium based on energy accumulation features of inverter. The method includes the following steps: collecting instantaneous values of three-phase valve side current and calculating the derivatives of the three-phase valve side current according to the instantaneous values of three-phase valve side current; the derivative includes positive, negative and zero states; according to the derivatives of the three-phase valve side current, determining the locations of incoming valve and ongoing valve; based on the valve side current of the incoming valve and ongoing valve, calculating energy accumulation features of the 12-pulse inverter; predicting whether the commutation failure from the incoming valve to the ongoing valve will happen according to the states of the derivatives of the three-phase valve side current and the energy accumulation features of the 12-pulse inverter.

A converter arrangement has a line-commutated converter with an AC voltage terminal to be connected to an AC voltage grid via at least one phase line. The converter arrangement has at least one switching module branch that is arranged in series in the at least one phase line and that includes a series connection of switching modules at whose terminals bipolar voltages that sum to give a branch voltage are in each case able to be generated. A bypass branch is arranged in a parallel connection to the switching module branch. At least one switching device is arranged in the bypass branch. The switching device includes activatable semiconductor switches that are connected in antiparallel. There is also described a method for starting up the converter arrangement.

Apparatuses including multiple selectable circuit elements are described. In an example, an apparatus may include a power supply configured to output a voltage. The apparatus may further include a controller connected to the power supply and a transmission unit connected to the controller. The transmission unit may be configured to output power. The transmission unit may include comprising an inverter connected to the power supply. The inverter may include a high-side switching element. The transmission unit may further include a circuit element a circuit connected to the power supply. The circuit may be configured to select the circuit element. The circuit may include a switch connected between the inverter and the circuit element. The switch and the high-side switching element may be configured to be driven by the voltage outputted by power supply. The controller may be configured to control the power being outputted by the transmission unit.

Apparatuses including multiple selectable circuit elements are described. In an example, an apparatus may include a power supply configured to output a voltage. The apparatus may further include a controller connected to the power supply and a transmission unit connected to the controller. The transmission unit may be configured to output power. The transmission unit may include comprising an inverter connected to the power supply. The inverter may include a high-side switching element. The transmission unit may further include a circuit element a circuit connected to the power supply. The circuit may be configured to select the circuit element. The circuit may include a switch connected between the inverter and the circuit element. The switch and the high-side switching element may be configured to be driven by the voltage outputted by power supply. The controller may be configured to control the power being outputted by the transmission unit.

A converter arrangement has a line-commutated converter with an AC voltage terminal to be connected to an AC voltage grid via at least one phase line. The converter arrangement has at least one switching module branch that is arranged in series in the at least one phase line and that includes a series connection of switching modules at whose terminals bipolar voltages that sum to give a branch voltage are in each case able to be generated. A bypass branch is arranged in a parallel connection to the switching module branch. At least one switching device is arranged in the bypass branch. The switching device includes activatable semiconductor switches that are connected in antiparallel. There is also described a method for starting up the converter arrangement.

This application discloses an electrical system and an electrical apparatus. The electrical system includes: a first-stage conversion module including a plurality of first controllable switches; a second-stage conversion module including a plurality of second controllable switches; a first digital signal processor configured to control the first controllable switch; and a second digital signal processor configured to control the second controllable switch, where a first output crossbar switch of the first digital signal processor is configured to supply a first internal signal to a first output port, so that the second digital signal processor receives the first internal signal within a preset time through a second input port. The internal signal of the first digital signal processor can be enabled to be transmitted to the second digital signal processor within a relatively short time, thereby reducing a time interval for triggering a protection action between the two digital signal processors.

The present invention is directed to provide a semiconductor device capable of protecting a switching element even though having a capacitor connected to a control signal input terminal of the switching element. Semiconductor device includes an IGBT including a gate configured to be input a gate signal and a current detection terminal used to detect at least one of overcurrent or short-circuit current, a gate capacitor arranged between the gate and a reference potential terminal, the gate capacitor being disconnected from the gate as needed, and a disconnection unit configured to disconnect a connection between the gate capacitor and the gate when a detection current being a current output from the current detection terminal is equal to or larger than a first current set on a basis of a minimum current causing oscillation in a loop circuit formed by including the IGBT and the gate capacitor.

The present invention is directed to provide a semiconductor device capable of protecting a switching element even though having a capacitor connected to a control signal input terminal of the switching element. Semiconductor device includes an IGBT including a gate configured to be input a gate signal and a current detection terminal used to detect at least one of overcurrent or short-circuit current, a gate capacitor arranged between the gate and a reference potential terminal, the gate capacitor being disconnected from the gate as needed, and a disconnection unit configured to disconnect a connection between the gate capacitor and the gate when a detection current being a current output from the current detection terminal is equal to or larger than a first current set on a basis of a minimum current causing oscillation in a loop circuit formed by including the IGBT and the gate capacitor.

A power conversion device includes a voltage-type power converter and a current-type power converter each of which performs power conversion between AC and DC, and a controlling circuitry, and power is transmitted/received between AC sides via a DC circuit. In first starting control for starting the voltage-type power converter and the current-type power converter, the controlling circuitry controls a semiconductor element of at least one of the voltage-type power converter and the current-type power converter, to adjust DC voltage at DC terminals of the voltage-type converter to a set first voltage value, thereby controlling current flowing through the DC circuit to be first current not greater than a rated current value of the semiconductor elements.