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Power quality in distribution networks is already a concern in many European Countries where there is a strong presence of renewable energy generation. There is therefore a growing interest in new technologies able to improve the power quality level. Among them, the Open Uninterruptible Power Quality Conditioner (Open UPQC) is a possible solution. The system consists of a main three-phase AC/DC power...
This paper investigates a new approach for the diagnosis of Rotor asymmetry in Wound-Rotor Induction Machines (WRIM). The method is assessed in a Wind Energy Conversion System, where the rotor side of the WRIM is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. The control system affects electric quantities and their signature...
This paper presents a performance analysis of a synchronous reluctance motor (SynRM) drive under different faulty operating conditions. Considering the voltage source inverter, single power switch open-circuit faults and single phase open-circuit failures are introduced and their effects are analyzed regarding the performance evaluation of the SynRM. The comparison of normal and faulty operating conditions...
This paper presents a multi-functional control of a DC/AC inverter for Power Quality compensation of nonlinear and unequal local loads and grid integration of hybrid photovoltaic (PV) and battery energy storage systems. Multi-layer neural network estimator and a DC/DC converter are used for maximum power point tracking (MPPT) of PV array. The power system is 3-phase 4-wires and the DC/AC inverter...
It is well known that rotor speed estimation assumes a paramount importance for the correct diagnosis of bearings, air-gap eccentricities or rotor bar defects. In this paper, a new technique for rotor speed estimation using a modified Prony's method is proposed. The algorithm developed for this purpose, is based on tracking the frequencies of the rotor slot harmonics (RSH) which exist in stator currents...
Often encountered driving critical applications, synchronous machines (SM) require reliable condition monitoring systems. In this paper, the advantages of using the field winding current of a synchronous motor as an early indicator of machine faults are demonstrated. Analysis is carried out, both through simulation, via the use of finite element methods (FEM), and through experimentation, using a...
In this paper the external stray flux around a motor has been investigated as a possible new diagnostic instrument to detect generalized roughness. This very common bearing fault has been slightly considered in the literature so far. Stray flux was measured by two probes, one commercially available and one realized in laboratory; the diagnostic content of both signals has been compared also with the...
The double-fed induction generator wind turbine has recently received a great attention. The steady state performance and response of double fed induction generator (DFIG) based wind turbine are now well understood. This paper presents the analysis of stator and rotor flux linkage dq models operation of DFIG under different faults and at different locations.
Fault-diagnosis and fault-tolerant control of modern wind turbines with minimum hardware requirements are mandatory features in order to increase the reliability and availability levels with low costs. This paper presents a fault-tolerant permanent magnet synchronous generator (PMSG) drive for wind turbine systems, allowing to automatically reconfigure the drive operation when a current sensor fault...
In this paper, the power quality of multi-area microgrids is addressed. For this, Active Power Filters (APFs) and Distributed Generators (DGs) inverters are used. To achieve the reference value of power quality indices of different areas, a strategy based on cooperation between DGs and APFs is proposed. Hierarchical control is applied to control DGs inverters and APFs in a coordinated way. Primary...
Fault detection in induction motors operating in non-stationary regimes has become a need in today's industry. Moreover, the number of fed induction motors has significantly increased in recent years Therefore, several fault detection techniques have been lately proposed based, mainly, in an adequate input signal processing to obtain some fault signatures in the time and/or frequency domains. In this...
Bearing damage is the most common failure in electrical machines. It can be detected by vibration analysis. However, this diagnosis method is costly or not always accessible due to the location of the equipment and the choice of the implemented sensors. An alternative method is provided with the electrical monitoring using the stator current of the electrical machine. This work aims at developing...
This article explores the impact of belt looseness on electrical and mechanical quantities of a system driven by an induction motor and a belt-pulley transmission. The effects of this defect, for example the belt slipping or the apparition of spectral signatures in some measurements, are first investigated under steady state operation. Transient state tests are then performed to analyse, in the time...
This paper presents a comparison of two of the most sensitive methods to detect low-level turn-to-turn faults in the windings of three-phase transformers. The performance of the negative sequence component and of the space vector protection algorithms is tested under several internal and/or external fault conditions. The simulation results indicate that the fault detection sensitivity of both methods...
This paper presents a new method for analysis of the electromechanical interactions in induction motors due to internal faults. These faults generate often electromechanical torque with rather low pulsations causing speed ripples, which change to the Fourier spectra of phase currents. The MCSA method uses those spectra for diagnosis. It is important to predict the spectra precisely, both qualitatively...
Vibration and temperature analysis are the two dominating condition monitoring techniques applied to fault detection of bearing failures in wind turbine generators. Relative movement between the bearing inner ring and generator axle is one of the most severe failure modes in terms of secondary damages and development. Detection of bearing creep can be achieved reliably based on continuous trending...
Mechanical cutting technology is a worldwide method, used to cut the magnetic cores of the electrical machines nowadays. The manufactures of the electrical devices prefer cutting the non oriented steel through this classical method, due to the fact that it is the cheapest of all. Non oriented silicon iron alloys (NO FeSi) are mainly characterized by specific energy losses. The mechanical properties...
In this paper, a low power squirrel cage induction motor was modeled by using Finite Element Method (FEM) for the eccentricity cases. Different types of eccentricity (static, dynamic and mixed) at different degrees were studied with the simulation and test results. The effects of the eccentricity on the motor performance in terms of the air gap flux density, current and torque characteristics were...
According to statistics, bearings are the most often failing elements of low voltage motors. At the same time diagnostics of rolling element bearings constitutes a well-established part of the rotating machinery condition monitoring domain. In many cases however the cost of installing a high-end accelerometer based bearing condition monitoring system, which is currently the most common approach in...
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