A power conversion system includes: a self-excited converter connected between an AC power system, and a first DC main line and a DC return line; a separately-excited converter connected between the AC power system, and the DC return line and a second DC main line; and a control device. When activating the self-excited converter and the separately-excited converter, the control device activates the self-excited converter, and after completion of activation of the self-excited converter, activates the separately-excited converter. The self-excited converter can be activated first to take advantage of a function of the self-excited converter that is not included in the separately-excited converter.

The invention relates to a fault transient features optimization method and system of AC/DC system based on dissipated energy, which belongs to the HVDC transmission technology and is used to solve the problem that the DC pulsed current is too high and the generator power angle swing of the AC system on the rectifier side is too large during the process of the HVDC transmission system restart on fault. The method includes the following steps: obtaining the output current and outlet bus voltage of the generator during the whole process of fault recovery of the AC/DC system under the current control parameters when adjusting the control parameters of the rectifier, and obtain multiple sets of control parameters and their corresponding output current and outlet bus voltage of the generator during the whole process of fault recovery of the AC/DC system; for each set of control parameters, calculating cumulative value of dynamic dissipated energy of the generator under the set of control parameters based on the output current and outlet bus voltage of the generator during the whole process of DC system fault recovery; selecting the set of control parameters that minimizes the cumulative value of dynamic dissipated energy of the generator as the optimal control parameter in the process of fault transient features optimization.

A boost PFC converter includes a rectifier, a converter and an output stage comprising an output capacitor where the DC output voltage is provided across the output capacitor. The rectifier includes four rectifying elements connected in a full bridge configuration where the upper two of these four rectifying elements are thyristors and where the lower two are diodes. In that the thyristors are controlled such as to be open for only a part of each half period of the input voltage, the amount of current per half period that is passed to the output capacitor is controllable and can be made very small. Accordingly, the charge current for precharging the output capacitor can be controllably limited such that a bulky precharge resistor is not required anymore to avoid high inrush currents.

A excitation system and a generator arrangement with the excitation system is proposed. The excitation system comprises a converter adapted for converting an AC current to a DC current, a switching device for short circuiting an AC input of the converter, and an arc detection device for detecting an arc fault in the excitation system and for actuating the switching device upon detecting the arc fault. Therein, the switching device comprises an irreversible switch adapted for short circuiting the AC input such that the arc fault is quenched. This provide a comprehensive protection against arc faults.

A excitation system and a generator arrangement with the excitation system is proposed. The excitation system comprises a converter adapted for converting an AC current to a DC current, a switching device for short circuiting an AC input of the converter, and an arc detection device for detecting an arc fault in the excitation system and for actuating the switching device upon detecting the arc fault. Therein, the switching device comprises an irreversible switch adapted for short circuiting the AC input such that the arc fault is quenched. This provide a comprehensive protection against arc faults.

A boost PFC converter includes a rectifier, a converter and an output stage comprising an output capacitor where the DC output voltage is provided across the output capacitor. The rectifier includes four rectifying elements connected in a full bridge configuration where the upper two of these four rectifying elements are thyristors and where the lower two are diodes. In that the thyristors are controlled such as to be open for only a part of each half period of the input voltage, the amount of current per half period that is passed to the output capacitor is controllable and can be made very small. Accordingly, the charge current for precharging the output capacitor can be controllably limited such that a bulky precharge resistor is not required anymore to avoid high inrush currents.

A power control method of a power control device, includes: rectifying, by a rectifier, an input current of a system including the power control device; sensing, by a current sensor, a first current through a first switch and a second current through a second switch, wherein the first switch and the second switch are connected to an output of the rectifier; filtering the sensed first current and the sensed second current through a low pass filter; sampling, by a processor, the filtered first current and the filtered second current once per switching cycles of the first switch and the second switch; and performing balancing control based on the sampled first current and the sampled second current such that an average value of the first current through the first switch and the second current through the second switch is uniform or is substantially uniform for a period.

A power control method of a power control device, includes: rectifying, by a rectifier, an input current of a system including the power control device; sensing, by a current sensor, a first current through a first switch and a second current through a second switch, wherein the first switch and the second switch are connected to an output of the rectifier; filtering the sensed first current and the sensed second current through a low pass filter; sampling, by a processor, the filtered first current and the filtered second current once per switching cycles of the first switch and the second switch; and performing balancing control based on the sampled first current and the sampled second current such that an average value of the first current through the first switch and the second current through the second switch is uniform or is substantially uniform for a period.

The present description concerns a circuit for converting from a first alternating voltage to a second voltage. The circuit includes: a first thyristor; a first control circuit of the first thyristor; a power factor correction circuit comprising a coil; and a first circuit configured to convert a third voltage into a fourth DC voltage. The third voltage corresponds to a difference between a potential at a first node connected to an output node of the coil and a reference potential. The fourth DC voltage is configured to supply the first control circuit of the first thyristor, and is referenced with respect to the same reference potential as the third voltage.

The present description concerns a circuit for converting from a first alternating voltage to a second voltage. The circuit includes: a first thyristor; a first control circuit of the first thyristor; a power factor correction circuit comprising a coil; and a first circuit configured to convert a third voltage into a fourth DC voltage. The third voltage corresponds to a difference between a potential at a first node connected to an output node of the coil and a reference potential. The fourth DC voltage is configured to supply the first control circuit of the first thyristor, and is referenced with respect to the same reference potential as the third voltage.