An interface arrangement is configured to couple an alternating current, AC, power system with a direct current, DC, power system, or vice versa. The interface arrangement includes a plurality of series-connected converter modules. Each converter module includes at least one multi-level converter cell configured to provide a voltage contribution to at least a portion of an AC waveform for example based on voltage of the DC power system. Each converter module includes at least one converter valve, electrically connected to the multi-level converter cells and including at least two anti-parallel thyristors. The converter valves are switchable between conducting states with a selected current conduction direction and a non-conducting state so as to selectively control polarity of any voltage contribution provided by the at least one multi-level converter cell. The converter valves can also serve as fault protection, e.g. to divert overcurrents.

The application provides a cascade system distributed control method and device. The method including: taking an output of a closed-loop control for regulating an AC current of the power module as a reference value of a bridge arm voltage; according to the reference value of the bridge arm voltage to obtain an amplitude of the bridge arm voltage, taking the amplitude of the bridge arm voltage as a feedback signal, and after closed-loop control and regulation together with the AC current of the power module, adjusting the reference value of the bridge arm voltage; and controlling the bridge arm voltage according to the reference value of the bridge arm voltage, wherein in at least one working mode of the cascade system, a change of parameters reflecting an active current has a monotonic relation with a change of the amplitude of the bridge arm voltage.

A converter control arrangement (18) for regulating the output current of a dc source power converter (16) comprises a current regulator (20) for regulating the output current based on a comparison of an output current value (I.sub.out) of the dc source power converter (16) with a desired target current value (I.sub.tgt). When the output voltage value (V.sub.out) of the dc source power converter (16) is within a normal operating voltage range between minimum and maximum voltage values (V.sub.min, V.sub.max) defined with respect to a voltage reference value (V.sub.ref) of the dc source power converter (16), the converter control arrangement (18) controls the target current value (I.sub.tgt) so that it is equal to a desired reference current value (I.sub.ref). When the output voltage value (V.sub.out) is outside the normal operating voltage range, which typically indicates a fault condition, the converter control arrangement (18) modulates the reference current value (I.sub.ref) to provide a target current value (I.sub.tgt) that is less than the reference current value (I.sub.ref).

The present invention discloses an LCC and MMC series-connected HVDC system with DC fault ride-through capacity, comprising rectifier and inverter linked by DC transmission line; Both the positive pole and the negative pole of the rectifier and the inverter consist of line-commutated converter and modular converter in series-connection; the modular converter adopts one MMC or several parallel-connected MMCs. The present invention has the advantage of low cost, low power loss and high reliability of the LCC, as well as flexible control, low harmonics and AC voltage support of the MMC. Further, the present invention is able to deal with DC fault by itself, hence additional DC fault clearing equipment is not needed. As a result, the present invention is suitable for the field of long-distance large-capacity power transmission and has broad development potential.

A redundant energy acquisition circuit of a power module includes at least one power semiconductor device, a first capacitor, and a first bypass switch. The redundant energy acquisition circuit of the power module includes: a power supply board acquiring energy from the first capacitor, supplying power to a control board, and charging a discharge circuit. A first charging circuit has one end connected to a positive electrode of the first capacitor and another end connected to the discharge circuit, and charges the discharge circuit when the power supply board is not operating normally. The control board controls the discharge circuit to close. The discharge circuit discharges and triggers the first bypass switch to close after the discharge circuit is closed.

The present disclosure provides a system for controlling a power device including one or more power elements, one or more drive modules configured to provide a drive signal with respect to the one or more power elements through a signal line and provided with a first wireless module, and an upper level controller configured to a control signal with respect to the one or more drive modules through a signal line and provided with a second wireless module corresponding to the first wireless module, wherein each of the one or more drive modules transmits state information of the one or more power elements and the one or more drive modules to the second wireless module through the first wireless module, and the upper level controller transmits a control signal corresponding to the state information to the first wireless module through the second wireless module.

A configuration for replacing a multi-phase transformer includes a plurality of single phase transformers each having a housing which is filled with an insulating fluid and in which a core with a high-voltage winding and a low-voltage winding is disposed. The configuration can be set up flexibly and also connected easily and conveniently to a supply network or consumer network by providing each housing with at least one cable connection and connecting each cable connection through a cable line to an outdoor connection which is air insulated, constructed for outdoor use and set up separately from the housing.

A wind power generation system according to the present invention includes: a DC bus; a plurality of feeders connected to the DC bus for transmitting DC powers to the DC bus; a plurality of wind power generators; a plurality of AC/DC converters connected one by one to each of the wind power generators for converting AC powers generated by the connected wind power generators, into DC powers, and outputting the DC powers to the feeders; and a DC breaker and a diode, which serve as a current limiting unit installed on each of the feeders for preventing a DC current from flowing from the DC bus into the feeder.

A direct current (DC)-DC converter includes a transformer and a gas tube-switched inverter circuit. The transformer includes a primary winding and a secondary winding. The gas tube-switched inverter circuit includes first and second inverter load terminals and first and second inverter input terminals. The first and second inverter load terminals are coupled to the primary winding. The first and second inverter input terminals are couplable to a DC node. The gas tube-switched inverter circuit further includes a plurality of gas tube switches respectively coupled between the first and second inverter load terminals and the first and second inverter input terminals. The plurality of gas tube switches is configured to operate to generate an alternating current (AC) voltage at the primary winding.

A DC connection system for renewable power generators includes a first monopole DC collection network, a second monopole DC collection network and a first bipole transmission system. The first monopole DC collection network aggregates positive-valued DC voltage outputs of a first cluster of renewable power generators onto a positive terminal of the first monopole DC collection network. The second monopole DC collection network aggregates negative-valued DC voltage outputs of a second cluster of renewable power generators onto a negative terminal of the second monopole DC collection network. The first bipole transmission system is coupled to the positive and negative terminals of the monopole DC collection networks, for transferring the aggregated power to a power grid substation.