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The interaction between wind power plants (WPPs) and grid, results in increasing short circuit level and decreasing low-voltage ride-through (LVRT) capability problems during fault condition. In this paper, the transformer-type fault current limiter (TFCL) based on the DC reactor is used for solving these problems. The proposed TFCL is based on the conventional TFCL in which the superconducting element...
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...
Variable-speed turbines have gained increasing importance in pumped-storage power plants since they present big advantages compared to the classical topology with a synchronous generator. Within the variable-speed solutions, the one employing a doubly-fed induction generator (DFIG) has become the preferred alternative for large installations since it provides the advantages of variable-speed operation...
This paper investigates the single-switch short-circuit fault response of a permanent magnet (PM) machine drive using a current source inverter (CSI). The CSI offers some appealing advantages over conventional voltage-source inverters (VSIs) during short-circuit fault conditions originating inside the inverter. Two post-fault strategies are investigated in this paper, consisting of either: 1) turning...
Variable-speed turbines have gained increasing importance in pump-storage power stations since they present big advantages compared to the classical topology with a synchronous generator. Within the variable-speed solutions, the one employing a doubly-fed induction generator (DFIG) has become the preferred solution for large installations since it provides the advantages of variable-speed operation...
Through the analysis of the electromagnetic properties for the rotor coil of turbine generator, we obtained the main magnetic field variation characteristics for the rotor winding and put forward the short circuit fault between rotor inter-turns causing the potential difference and circulation between the parallel branches of generation stator winding spectral method was applied on the spectrum analysis...
In case of three-phase short circuit fault occurring at the terminal of a doubly-fed induction generator (DFIG), the rotor current characters of DFIG are analyzed from the viewpoint of the flux linkage, and the expression of the rotor current is deduced together with the estimated expression of the maximum rotor current. Based on above analysis, the max rotor currents and their appearing times with...
The fault ride-through ability of doubly fed wind generators (DFIG) has got more and more attention. New grid codes for interconnection of wind turbines required that wind turbines remain connected to the grid and actively contribute to the system stability during and after grid faults. Uninterrupted excitation of DFIG can both avoid running over-speed of wind turbines during grid faults and accelerate...
A wind power plant consists of a large number of turbines interconnected by underground cable. A pad-mount transformer at each turbine steps up the voltage from generating voltage (690 V) to a medium voltage (34.5 kV). All turbines in the plant are connected to the substation transformer where the voltage is stepped up to the transmission level. An important aspect of wind power plant (WPP) impact...
The aim of this paper is to develop a technique for detecting an inter-turn short-circuit in a wound rotor induction machine working as generator by using the bispectral analysis. Bispectral analysis is able to provide more information than power spectrum analysis. In the present investigation, the rotor and stator currents of the machine operating in both healthy and faulty modes are thoroughly analyzed...
It is well known that stator winding faults such the inter-turn short circuit are the most frequent source of breakdowns in induction motors. Early detection of any small inter-turn short circuit during motor operation would eliminate some subsequent damage to adjacent coils and stator core, reducing then the repair cost. To achieve this purpose, the present paper proposes a new method, called Park-Hilbert...
The aim of this paper is to develop a technique for detecting a real rotor inter-turn short-circuit fault in a wound rotor induction machine working as generator by using the spectral and the bispectral analysis. The stator currents provide interesting signatures since the rotor inter-turn short-circuit fault introduces new harmonics in the stator windings. Hence, in this paper, it is proved that...
In this paper a simple dynamic circuit-based model for a rotor surface mounted PMSM with inter-turn winding short-circuit fault is presented. Finite element analysis is used for parameter determination and study the PMSM under fault conditions. The Analytical expressions are proposed for determining the fault model parameters. The proposed circuit model and parameter expressions are validated by time...
This paper deals with the study of interturn short circuits in rotor windings of a synchronous generator using FEM. Results obtained for magnetostatic and magnetodynamic cases are presented and discussed.
The paper describes a system for automated detection of incipient faults in induction machines. The system is based on the Motor Current Signature Analysis method (MCSA) and aimed to be applied in a thermal electric power plant in south Brazil. First, the mechanism of fault evolution is introduced and clarified regarding the most common induction motor faults: stator winding short-circuits, broken...
The inter-turn short circuits fault of field windings is a common fault in generators. According to the multi-loop method of AC machines, this paper proposes multi-loop mathematical model of turbine generator with inter-turn short circuits fault of field windings. Based on the model, the normal operation and the short circuits fault operation of generator with no load have been simulated combining...
For DFIG (doubly fed induction generator)-based wind turbines, crowbar is a commonly used protection method against surge current caused by sudden drop of the grid voltage during the period of LVRT (low voltage ride-through). Based on detailed analysis of the transient flux characteristics of DFIG with the crowbar fired, a simplified model is proposed to analyze and approximate the short circuit current...
This paper presents a simple DFIG-based wind farm equivalent model which can be used to quantify a wind farm's short circuit current contributions to the grid, e.g. for the purpose of protective relaying setting. The model has taken the equivalent impedances Xss and the equivalent potential E'q as the characteristic parameters. By analyzing the short circuit behavior of a doubly fed induction generator...
Short circuit current characteristics of wind generators have been studied in this paper. Two types of wind generators have been considered. One is the induction generator; the other is the doubly-fed induction generator (DFIG). As to DFIG, there is always a crowbar to protect the power electronic converter at the rotor side. So the short circuit current of DFIG has been analyzed with consideration...
The use of doubly fed induction generator (DFIG) in large wind turbines has become quite common over the last few years. But the main disadvantage of DFIG is that it's very sensitive to grid disturbance, such as short circuit and voltage dip. It could cause over current in rotor and stator windings. This paper investigates the effect of wind turbine altitude and height of tower on short circuit current.
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