The present disclosure relates to semiconductors. Some embodiments may include a series circuit arrangement of power semiconductors comprising: cooling-water boxes arranged on the semiconductors and electrically connected to them; two cooling-water distributor lines; respective branchings on the cooling-water distributor lines for the cooling chambers; and a control electrode arranged on the cooling-water distributor lines. The cooling chambers are connected in parallel between the cooling-water distributor lines with respect to a cooling-water stream. The cooling chambers are connected to the branchings via a respective connecting line. For at least some of the cooling chambers, the branchings on the cooling-water distributor lines are arrayed relative to the position of the respective cooling chamber in offset manner in relation to a geometrically shortest possible link to the cooling-water distributor lines, so that a difference of potential between the cooling chambers and the branchings is minimized.

Disclosed in the present invention is a hybrid back-to-back direct current transmission system. The system includes an LCC converter and a VSC converter in a back-to-back connection, and a first changeover switch, a second changeover switch, a third changeover switch and a fourth changeover switch. The first changeover switch is connected to a first alternating current system and the LCC converter; the second changeover switch is connected to the first alternating current system and the VSC converter; the third changeover switch is connected to a second alternating current system and the VSC converter; and the fourth changeover switch is connected to the second alternating current system and the LCC converter. In forward power delivery, the first changeover switch and the third changeover switch are closed; and in reverse power delivery, the second changeover switch and the fourth changeover switch are closed. Thereby, it is ensured that the VSC converter always performs inversion operation in any power direction, so as to avoid the problem of potential commutation failure for the LCC converter when being in inversion operation. Also provided is a fast power flow reversal control method of the hybrid back-to-back direct current transmission system.

A power conditioner is provided that includes a heat dissipating member, multiple circuit boards, and a mounting auxiliary plate. A power conditioner circuit including an electric heat generating element is formed on each of the circuit boards. The circuit boards are mounted on a front surface of the heat dissipating member. Heat dissipating fins are arranged on a back surface of the heat dissipating member. Preferably, the heat dissipating member is formed from a material having high heat dissipation property. The mounting auxiliary plate is fixed to the back surface side of the heat dissipating member and provided with a through hole for mounting to a wall. The mounting auxiliary plate has higher rigidity than the heat dissipating member.

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.

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.

A load commutated converter interconnects an AC power grid with an AC load and comprises a grid-side converter, a DC link and a load-side converter. A method for controlling the load commutated converter comprises: determining a gridside firing angle for the grid-side converter; determining a load-side firing angle for the load-side converter; determining a grid voltage of the AC power grid; modifying the grid-side firing angle and/or the load-side firing angle based on the grid voltage, such that when an undervoltage condition in the AC power grid occurs, the operation of the load commutated converter is adapted to a change in the grid voltage; and applying the grid-side firing angle to the grid-side converter and the load-side firing angle to the load-side converter.

A system includes multiple electrical nodes connected in series to a primary power source via transmission lines. Each node includes a power converter that can receive first power from the primary power source or another upstream node. The power converter can change a voltage level and/or a frequency of the first power. Each node also includes a high-speed synchronous rotating machine (HSRM), which includes an inertial storage flywheel, a rotating excitation assembly, stator windings, and a synchronous motor coupled to an induction generator. The HSRM can boost a voltage level between an input and output to compensate for a voltage drop of the first power. At least one of the nodes further includes an inductive power coupler to electrically couple the node to a mobile power source that provides second power to the node and receives a portion of the first power from the node using contactless inductive power transfer. The system includes a combination of AC and DC power transmission techniques and associated bidirectional power converters.

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.

Disclosed in the present invention is a hybrid back-to-back direct current transmission system. The system comprises an LCC converter and a VSC converter in a back-to-back connection, and a first changeover switch, a second changeover switch, a third changeover switch and a fourth changeover switch. The first changeover switch is connected to a first alternating current system and the LCC converter; the second changeover switch is connected to the first alternating current system and the VSC converter; the third changeover switch is connected to a second alternating current system and the VSC converter; and the fourth changeover switch is connected to the second alternating current system and the LCC converter. In forward power delivery, the first changeover switch and the third changeover switch are closed; and in reverse power delivery, the second changeover switch and the fourth changeover switch are closed. Thereby, it is ensured that the VSC converter always performs inversion operation in any power direction, so as to avoid the problem of potential commutation failure for the LCC converter when being in inversion operation. Also provided is a fast power flow reversal control method of the hybrid back-to-back direct current transmission system.

An AC-AC converter system includes transformer arrangements and HVDC converter units on primary and secondary sides of the system, respectively. The system exhibits first and second three-phase AC networks, and the converter units are interconnected via a DC connection. By integrating at least part of two transformer arrangements in one transformer unit, a cost efficient transformer configuration can be achieved.