The present invention relates to an apparatus and a method for synchronizing a clock of VBE in a HVDC system capable of increasing reliability by synchronizing the clock of the VBE in the HVDC system to suppress harmonic generation and generate duplicate clock to supply stable clock to submodules. The apparatus for synchronizing the clock of the VBE in the HVDC system comprises an operation board for creating a reference clock and an interface board for controlling submodules on or off being synchronized to a reference clock.

The present invention discloses a charging method for a sub-module based hybrid converter. By setting a half-controlled charging link of half-blocking all full bridge sub-modules in a charging process, and raising the voltages of half bridge sub-modules to reach the starting point of a half bridge sub-module based self-powered supply in an uncontrolled stage of the half bridge sub-modules, the starting point of the sub-module based self-powered supply is increased, and the design difficulty of the sub-module based self-powered supply is reduced. The present invention also discloses another charging method for a sub-module based hybrid converter. The above objective can also be achieved by setting a half-controlled charging link of bypassing all full bridge sub-modules in the charging process.

A system for generation and distribution of high voltage direct current (HVDC) within a contained power domain named POD and methods for making and using the same. The system and methods efficiently power Information Technology racks deployed to a data center environment, advantageously providing features and functions highly desirable for a specific application.

An electrical assembly includes a power converter having first and second DC terminals which are connectable to a DC electrical network. The power converter also includes converter limbs connected between the first and second DC terminals. Each converter limb includes an AC terminal that is connectable to a respective AC phase of a multi-phase AC electrical network. Each converter limb also includes limb portions, each connected between a corresponding AC terminal and a respective one of the first and second DC terminals. Each limb portion includes switching element(s). The electrical assembly includes a single grounding circuit having a reactor configured to provide a current path for alternating current with a high impedance to ground and a current path for direct current with a low impedance to ground. The grounding circuit is arranged so that only one of the AC phases is connected to ground via the grounding circuit.

Disclosed embodiments relate to a monitoring system for detecting an error of a harmonic filter in a high voltage direct current (HVDC) transmission system is disclosed. In some embodiments, the monitoring system comprises a harmonic filter including one or more capacitor units, a monitoring sensor unit sensing a voltage of at least one of the one or more capacitor units, and, a control unit monitoring a voltage error of the at least one capacitor unit using the sensing result.

A power loss measuring system is provided for measuring power loss in a harmonic filter included in a High Voltage Direct Current (HVDC) transmission system. The power loss measuring system may include a harmonic filter, a monitoring sensing unit, and a controller. The harmonic filter may include a plurality of elements. The monitoring sensor unit may sense variation in impedance of each of the plurality of elements. The controller may obtain power loss in the harmonic filter using amount of variation in impedance of each of the plurality of elements.

There is provided an electrical assembly for use in an electrical system. The electrical assembly comprises a DC path. The DC path includes: a DC power transmission medium; and a current commutation device, the current commutation device including a switching element and an energy absorbing element, the switching element arranged to permit a current flowing, in use, through the DC path to flow through the switching element and at the same time bypass the energy absorbing element, wherein the electrical assembly further includes a control unit programmed to selectively control the switching of the switching element to commutate the current directly from the switching element to the energy absorbing element in order to increase the resultant voltage drop caused by the flow of direct current through the DC path in which the current commutation device is connected and thereby oppose the flow of the current through the DC path.

The present disclosure provides a parameter design method for a series passive impedance adapter applicable to a VSC-HVDC transmission system, to resolve the technical problem that high-frequency resonance may occur when impedance of a VSC-HVDC transmission system is mismatched with that of a sending-end or receiving-end grid. A parameter design goal of the present disclosure is that reactive power consumed by a series passive impedance adapter is not more than A times rated power of a converter, and a loss of the series passive impedance adapter in a fundamental wave is B times the rated power of the converter. The parameter design method for a series passive impedance adapter applicable to a VSC-HVDC transmission system in the present disclosure can realize a positive impedance characteristic within a concerned frequency band and completely eliminate a risk of harmonic resonance.

A wind farm side voltage source converter comprises a DC terminal for connection to a DC transmission link, an AC terminal for connection to a wind farm that includes at least one wind turbine, and a main controller. The main controller is configured to modify an active power demand (Pdemand) of the voltage source converter which is received from a higher level controller by introducing an artificial inertia factor and/or in response to a measured DC voltage (Vdc_msr) at the DC terminal.

A method and apparatus for controlling a voltage source converter to energize a DC link. A voltage order generating module generates a voltage order for controlling the voltage source converter to generate a DC voltage on the DC link. An oscillation damping module monitors the DC current flow to determine an indication of current oscillation and the voltage order is based on a voltage reference signal which is modulated by the indication of current oscillation to provide oscillation damping.