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Rotor winding interturn short circuit is the main fault of synchronous electric machines, it is of great significance to the safe and stable operation of the machine to discover and handle the fault timely. In view of this, the fault positioning method of rotor turn-to-turn short circuit of synchronous machines was studied. The mathematic expression of exciting magnetomotive force (e-m.m.f.), electromotiveforce...
Renewable energy sources integration in power systems leaded to the development of new mandatory standards for integrated system operation. During grid faults in power supply network, wind turbines must face major challenge, imposed by strict grid codes, particularly Fault Ride — Through capability. In the event of a grid disturbance, the rotor of the wind turbine generator is susceptible to high...
In complex systems, such as military organizations, a large number of technical resources requiring regular maintenance is used. These resources are often exposed to difficult working conditions increasing the probability of a fault occurrence. Fault diagnosis as a part of the maintenance process is often a complex process, which is why expert systems for fault diagnosis are developed. One of the...
The main advantage of the doubly fed induction generators (DFIG) over the synchronous generators is the small size converter which is located in the rotor circuit. However, this advantage can cause a problem during grid faults, because the over voltages and currents that will occur on the rotor circuit can damage the rotor side converter (RSC), if it is not over-dimensioned or protected for such high...
\n order to find a new online method to identify the rotor inter-turn short circuit fault of brushless excitation synchronous generator, this paper analyzed the changes of electromagnetic properties and electrical parameters and got the fault characteristics that field current increased and reactive power decreased after fault. The relative deviation of generator output reactive power before and after...
To research the influence of rotor structure on field current and rotor electromagnetic field of a turbine generator under Out-of-Phase Synchronization(OPS), an 2-D Field-Circuit-Grid Coupled Model (FCGCCM) of the 150MW turbine generator is established. By using the established FCGCCM, the influence on field current and the field current oscillation ratio (FCOR) under OPS of 180° was studied, when...
Doubly-fed wind generator is highly sensitive to voltage variations of the grid, which poses limitations for wind power plants during the grid integrated operation. This paper proposes a new control strategy for rotor side converter of doubly-fed induction generator (DFIG) using energy-based control method based on Port-Control Hamiltonian (PCH) theory and L2 disturbance attenuation. The proposed...
A simple and cost-effective software-based resolver to digital converter together with a permanent magnet synchronous motor control system were presented. The proposed method incorporates software generation of the resolver carrier and using anti-tangent calculation for synchronous demodulation of the resolver outputs signal in such a way that there is a substantial savings on hardware like the costly...
With the integration of wind generators in the distributed network, the power flow and fault current characteristic have been changed. The negative sequence impedance of the doubly fed induction generator (DFIG) is quite different from the positive sequence impedance after the crowbar circuit is activated. This characteristic poses a big challenge on the operation of the protection system. Traditional...
This paper investigates a drive system control strategy for grid-connected wind energy conversion systems with doubly-fed induction generator and its behavior under grid fault operation. During grid faults there is a possibility for undefined load situations in the mechanical drive system. These loads are able to start oscillations in the drive system not only in the shaft but in the blades as well...
The paper dwells on calculation method for the negative-sequence currents in the generator circuit in unbalanced conditions. The method considers shunting effect of the load, comprising asynchronous motors. It is based on a software complex for calculating electromechanical transients, designed on the basis of the single-phase network positive-sequence diagram and supplemented with straight-line negative...
This paper presents a study of the wind turbine in normal and faulty situation. In the latter, suitable residual generation is performed to detect and isolate three sensor faults in the wind turbine system. The study was conducted on FAST coded simulator, designed by the US National Renewable Energy Laboratory's National Wind Turbine Center. The obtained results provide a good fault detection and...
This paper develops a control strategy for a large wind turbine based on the squirrel cage asynchronous generator (SCAG). In addition, the transient behavior during Low Voltage Ride Through (LVRT) of the system is studied. To this end, the wind turbine connected to the grid is controlled in such way to inject maximum power into the grid and provide a reactive power to regulate the grid voltage, in...
In this paper, a fault assessment of a multiphase permanent magnet generator designed for ‘more electric engine’ aeronautic applications is presented. The distribution of various electrical faults occurring in three-phase machines that is available in the literature helped the authors to identify the most probable fault types. The six-phase machine under observation is tested under these faults both...
Increasing worldwide demand for energy has made wind energy a forerunner as a renewable energy resource. Due to this, and due to the intermittent nature of wind, Wind Turbines (WT) reliability should be considered. Improving the reliability of a WT translates into reduced operation and maintenance cost. This highlights the aim of this paper which is a technical review on WTs critical failures as well...
This paper investigates a drive system control strategy for grid-connected wind energy conversion systems with doubly-fed induction generator and its behavior under grid fault operation. During grid faults there is a possibility for undefined load situations in the mechanical drive system. These loads are able to start oscillations in the drive system not only in the shaft but in the blades as well...
This paper presents the necessity of posing and solving inverse problems in the diagnostic procedures of electric machines. This is essential in order to achieve better and more precise results in the condition monitoring of the machines due to the growing complexity of the machine setups, which challenges the traditional electric machine diagnosis methods. An overview of the machine fault statistics...
Predictive pole-slip protection is not implemented in commercially available protection relays, since complex modeling of the network and generator is required to do such predictive detection. All pole-slip protection relays on the market will only trip a generator after it has pole-slipped one or more times. This paper introduces a pole-slip protection algorithm, which makes use of a simplified model...
Nowadays, grid code requirements demand that wind energy converters (WEC) remain connected to the grid during grid faults and contribute to the voltage support, in the same way as conventional power plants. WEC which are capable of ridding through grid faults providing voltage and reactive power support are connected to the grid via electronic power converters, increasing the failure risk and reducing...
Variable-speed doubly fed asynchronous (Type 3) and full converter-based (Type 4) wind turbine generators (WTGs) have complex fault current characteristics governed by proprietary controls. The control technique of some manufacturers is to produce balanced three-phase fault current during unbalanced faults. At present, short-circuit analysis tools commonly used by protection engineers are inadequate...
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