For the black start-up of DC micro-grids, three-phase charging resistors are required to limit uncontrollable surge current. The main drawback this method is difficulty in determining appropriate resistance value achieve a rapid and current with change grid parameters. To address problem, article proposes soft for micro-grid based on an improved two-level voltage source converter (VSC). Specifi...

Voltage source converter (VSC)-based high voltage direct current (VSC-HVDC) interconnectors can realize accurate and fast control of power transmission among AC networks, and provide emergency power support for AC networks. VSC-HVDC interconnectors bring exclusive fault characteristics to AC networks, thus influencing the performance of traditional protections. Since fault characteristics are r...

A doubly-fed induction generator’s (DFIG’s) sensitivity to external faults has motivated researchers to investigate the impact of various grid disturbances, such as voltage sags and short circuit faults, on its low-voltage ride-through (LVRT) capability. However, no attention has been paid to the impact of internal faults in voltage source converters (VSCs), that interface a DFIG with the grid,...

Voltage control and fast reactive power compensation are two main application area of Static Synchronous Compensator (STATCOM), which is a shunt connected voltage source converter (VSC) based FACTs controller using power semiconductor devices (particularly IGBT, GTO etc.).However, the total Statcom circuitry has complex and coupled system dynamics which require advanced controllers to achieve w...

Impedance models are widely used in assessing small signal stability of grid-tied voltage source converter (VSC) systems. Recent research has proven that impedance models of grid-tied VSC in both dq and sequence domains are generally Multi-Input Multi-Output (MIMO) systems, and the generalized Nyquist criterion has to be applied for stability analysis to these MIMO systems. However, finding Sin...

The aim of this study was to reveal the mechanisms by which zinc ions inhibit oral malodor. The direct binding of zinc ions to gaseous hydrogen sulfide (H2S) was assessed in comparison with other metal ions. Nine metal chlorides and six metal acetates were examined. To understand the strength of H2S volatilization inhibition, the minimum concentration needed to inhibit H2S volatilization was de...

OBJECTIVE morning breath contains elevated concentrations of volatile sulphur components (VSCs). Therefore, morning breath is recognised as a surrogate target for interventions on breath quality. Nevertheless, factors influencing morning breath are poorly understood. Our aim was to evaluate concentrations of VSC at the time of awakening. METHODS a procedure was developed to collect breath sam...

OBJECTIVE To investigate the topographic distribution of bacterial types and loads associated with mid-morning oral malodour on the tongue surface. DESIGN Fifty subjects with good oral health and at least 20 natural uncrowned teeth were included. Samples were taken with sterile brushes from the dorsal anterior (DA), dorsal middle (DM), dorsal posterior (DP), dorsal posterior to the circumvall...

As one of the key technologies of large scale access of distributed energy resources, the HVDC transmission system has great potential for further development. Therefore, in the past decades, the problem associated with HVDC converters connected to weak AC networks has become an important research field. The one of particular interest, and highest in consequences, is the AC voltage stability at...

High-voltage dc transmission based on voltage-source converter (VSC-HVdc) is quickly increasing its power rating, and it can be the most appropriate link for the connection of offshore wind farms (OWFs) to the grid in many locations. This paper presents a steady-state operation model to calculate the optimal power transmission of an OWF connected to the grid through a VSC-HVdc link. The wind tu...