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.
Multilevel converters are widely used in medium voltage applications. One of the most popular topologies in this field is the 18 pulses diode rectifier, which uses a mu Iti pu I so transformer that realizes a current harmonics cancelation that are generated by the three phase diode rectifiers. In this work an efficiency comparison of the aforementioned topology and a Multi-Cell Active-Front-End (AFE)...
This article presents a new approach for transformer inter-turn fault detection. Conventional differential scheme is provided with bias to prevent mal-operation in case of over-excitation, CT saturation, magnetising inrush, etc. However, this prevents conventional scheme from detecting inter-turn fault at incipient stage where less turns are involved in the fault. Proposed scheme overcomes this drawback...
This paper presents real-time simulation results of a 512-level modular multilevel converter (MMC). Using off-the-shelf computers and FPGA boards, the converter, including the 6 valves, 6 arm inductors and the transformer, is simulated with a time-step of 450 ns. Such a small time-step is required to ensure high accuracy when applying gating signals but also when observing fault conditions. Simulation...
This paper investigates two winding concepts for Permanent Magnet (PM) machines used for more electric aircraft systems where reliability is a concern. Analysis is carried out using two different surface mounted PM machines designed for low and high speed applications: a 12 slot, 10 pole machine with concentrated windings for rotorcraft swashplate actuation and a 36-slot 6-pole machine with distributed...
An intelligent approach artificial neural network (ANN) combined with genetic approach (GA) is presented for detection of stator winding related fault of switched reluctance machine. Switched reluctance machine (SRM) is known to be fault tolerant, however, is not fault free, and questions emerge as to powerful diagnostic methods. This paper takes an in-depth look at winding open-circuits ‘the worst...
One of the main challenges of voltage source converter based HVDC systems is DC faults. In this paper, two different modified half-bridge modular multilevel converter topologies are proposed. The proposed converters offer a fault tolerant against the most severe pole-to-pole DC faults. The converter comprises three switches or two switches and 4 diodes in each cell, which can result in less cost and...
The multi-level inverter system is becoming a very promising candidate to replace the conventional two-level inverter, but system reliability remains an open issue. The most common reliability problem is that power switch transistors have open-circuit or short-circuit faults during operation. In order to improve the accuracy of the fault diagnosis and accelerate the operation speed in a cascaded H-bridge...
The dynamic voltage restorers are efficient series compensation devices to improve power quality. Indeed, they are composed of a coupling transformer and power electronics to provide fast voltage sag correction and harmonics compensation. This paper focuses on a new topology of a coupling transformer for the dynamic voltage restorers which improves the protection of the voltage source converter against...
In this paper we address the problem of rotor faults in Wound Rotor Induction Machine by using two different signal processing methods to voltage between neutrals such as Standard deviation calculation and Hilbert Transform (HT). This last is employed as an effective technique for fault detection in induction machines. The mathematical simplicity of the proposed technique, compared with some commonly...
The detection of bearing damage using the stator current analysis is an important issue in condition monitoring. The modeling of a bearing damage can help to generate data for different loads and faults. These simulation data can be used to develop fault detection and classification algorithms. The aim of this work is to develop a model for the bearing damage effects, which enables the simulation...
In this paper, voltage control of stand-alone "Photovoltaic (PV)-Diesel Generator (DG)-Battery" system is presented when subjected to faults on distribution feeders. During the period of occurrence of fault and opening of fuse, high current flows through inverter leg which stops its operation. Moreover, fault creates huge unbalance due to opening of fuse of faulty phase(s). Therefore, a...
Modern civilization depends heavily on the consumption of electrical energy for industrial, commercial, agricultural, domestic and social purposes. However, for the current HVDC system, proper protection devices and logic are not yet as mature as the AC counterpart. This paper presents the fault analysis for the protection of the HVDC (65–765 kV range) grid, using PSCAD. Faults in the DC transmission...
Solid state transformers normally include a transformer whose operating frequency is well above the usual grid frequencies. These transformers are supplied by power electronic inverters such as an H-bridge. The average value of transformer supply voltage can drift to a non-zero value which may lead to saturation of the magnetic core. This paper presents an active control method to prevent saturation...
Understanding of faults and their impacts on the performance of Switched Reluctance Motor (SRM) is essential for fault detection and post fault control strategy development. In this paper, an 8/6 SRM is modeled and analyzed under various short circuit faults and operational conditions. Simulation and experimental investigation of the effects of fault in both transient and steady state is presented...
Eventual failures in induction machines may lead to catastrophic consequences in terms of economic costs for the companies. The development of reliable systems for fault detection that enable to diagnose a wide range of faults is a motivation of many researchers worldwide. In this context, non-invasive condition monitoring strategies have drawn special attention since they do not require interfering...
An original analytical expression is presented in this paper to obtain optimal currents minimizing the copper losses of a multi-phase Permanent Magnet Synchronous Motor (PMSM) under fault conditions. Based on the existing solutions [i]opt1 (without zero sequence of current constraint) and [i]opt2 (with zero sequence constraint), this new expression of currents [i]opt3 is obtained by means of a geometrical...
This paper deals with the issues related to the interconnection between the microgrid and main network. The Dynamic Voltage Restorer (DVR) is proposed as an interface between the main network and microgrid in order to improve reliability and limit fault currents. The performance of DVR is demonstrated during fault conditions in two different locations, firstly in the main grid and then within the...
This paper studies the operation of a microgrid under various scenarios with a focus on the effect of communication delays. The test microgrid is the CIGRE-IEEE low-voltage system, and a variety of loads are modeled in the system, including a nonlinear load, an impulse load, a battery, a highly capacitive load, and a highly inductive load. The simulation studies cover three scenarios: 1) a system...
DC-based microgrids are promising solutions to enhance the energy efficiency, reliability and safety of residential and commercial buildings, as well as to provide more effectively higher penetration of renewable energy resources into the electrical grid. However, despite the great effort that is being done by electronics, telecom/datacom and buildings sector companies and entities upon the standardization...
Multilevel converters with fault tolerant capability are getting increased importance in the HVDC systems. This paper describes the working principle and submodule capacitor voltage balancing issues of the Hybrid Cascaded Multilevel converter (HCMC). The converter involves lesser number of sub-modules and provides excellent DC side fault tolerant capability in an HVDC system. The paper analyzes the...
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.