The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Recently, modular multilevel converters (MMC) have attracted extensive research interest in the field of HVDC and motor drives. However in motor drives, it appears that the inherent problem of the fluctuation of capacitor voltage particularly at low frequencies limits its further application. This paper proposes a new back-to-back hybrid MMCs topology, of which one MMC is directly connected to the...
The requirement of a large number of sizeable capacitors in traditional modular multilevel converter (MMC) submodules is seen as a major barrier hampering its widespread use in medium-voltage applications. To reduce the value of capacitance, this paper presents a modified MMC (M-MMC) topology, which offers inherent alleviated capacitor voltage fluctuations compared with traditional MMC. Its operating...
The modular multilevel converter (MMC), eliminating the expensive and bulky multi-winding phase-shifting transformer compared with the cascaded H-bridge converter, is shown to be of great potential in the field of medium-voltage motor drive applications. However, special care needs to be taken for MMC driving motor at low speeds, since the voltage fluctuation of the submodule capacitors increases...
In the very recent years, the modular multilevel converter (MMC) topology has become the development trend of high-voltage high-power power conversion technologies. However, one specific issue associated with MMC is the necessity of very large capacitances, which stops it from reducing cost, increasing reliability, and improving power density. To reduce the capacitance of required capacitors, in this...
A novel scheme for obtaining the fundamental-frequency positive-sequence signals based on a combination of delayed signal cancellation (DSC) method and low-pass notch filter phased-lock loop (LPN-PLL) is proposed in this paper. DSC working in the stationary reference frame is used to obtain the fundamental-frequency positive-sequence voltage vector, while LPN-PLL is used to obtain pulsation and phase...
The impact of power quality disturbance is one of the major factors of power quality. S-transform (ST) is a very effective method for power quality disturbances analysis which provides frequency-dependent resolution while maintaining a direct relationship with the Fourier spectrum. This paper proposed a new approach for power quality disturbances recognition using modified S-transform with hyperbolic...
Doubly-fed induction generator (DFIG) is widely applied in Variable Speed Constant Frequency (VSCF) wind power system. In recent years the proportion of wind power became more and more in the electricity supply. The failure of power grid will lead to voltage drop and will cause system transient instability and may lead to partial or full paralysis. So Low Voltage Ride Through (LVRT) requirements is...
This paper presents a new approach for recognizing nonstationary signals in power quality (PQ) disturbances. Meanwhile the new approach includes the most types of PQ disturbance, such as voltage sags, swells, interruptions, transients and harmonics. The new model mainly includes two steps. Firstly, S-transform is used to analyze power system disturbance signals, and two most distinguishing features...
This paper presents a new approach for recognition of nonstationary signal in power quality (PQ) disturbance using S-transform and self-organizing mapping (SOM) neural networks. The most common types of the PQ disturbance, such as voltage sags, swells, interruptions, transients and harmonics, are studied. We utilize S-transform to process power quality disturbance signal. In this step, the obtained...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.