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The paper is concerned with the active and reactive power flow between the doubly fed induction generator harvesting wind power and the grid controlled by the rotor side converter. After deriving the basic equations in Appendices it builds up a block diagram for studying the dynamic processes and it applies them for investigating the slip - rotor current characteristics where rotor voltage components...
In this paper the impact of variable speed wind generators on power system transient stability is examined using a generic full converter wind generator model. First the developed model, appropriate for power system stability studies, is described and the grid-side converter control strategy during voltage dips is analyzed. Next, the contribution of a wind farm equipped with full converter wind turbines...
The control for a switched reluctance generator (SRG) with three-level power converter to increase output power is presented in this paper. First, the operation conditions and key factors to enhance output power of SRG are proposed. Then a three-level power converter with intermediate freewheeling boosts the magnetizing current and the average current in generation freewheeling region. Accordingly,...
This paper introduces a study for the small wind energy conversion system (WECS), which aims to select the optimum design parameters to achieve high performance system. The main features of the studied system are high efficiency, operation at maximum power point tracking (MPPT) and long battery lifetime. The Permanent Magnet Synchronous Generator (PMSG) operates at variable wind speed and it is connected...
This paper investigates the feasibility of using a topology with a squirrel-cage induction machine and a Vienna rectifier for a wind energy conversion system. Simulation results reveal that this configuration is advantageous with respect to energy efficiency and reliability compared to a traditional six-switch two-level inverter.
This paper presents an enhanced direct power control (DPC) algorithm for doubly fed induction generators (DFIG) capable of reducing the common mode voltage (CMV). Nowadays the DFIG is often used in high power wind energy conversion systems (WECS). A common problem of converter fed induction machines are the bearing damages due to the bearing currents. The source of this problem is the common mode...
Due to growing number of wind turbines (WT) within a wind farm (WF) scheduling of maintenance of turbines within the WF becomes challenging issue. Also, in instances when wind energy curtailments are required it can be difficult to decide which turbines should be shut down first. In this paper, a probabilistic methodology is presented to identify WT in the WF that face higher and lower wind speeds...
This paper implements of a three phase grid synchronization for doubly-fed induction generators (DFIG) in wind generation system. A stator flux oriented vector is used to control the variable speed DFIG for the utility grid synchronization, active power and reactive power. Before synchronization, the stator voltage is adjusted equal to the amplitude of the grid voltage by controlling the d-axis rotor...
This paper presents a more precise approach for static electromagnetic characterization of the variable speed switched reluctance generator (SRG) for application in the wind energy conversion system. The circuit-coupled two-dimensional finite element method (FEM) for magnetic characterization of switched reluctance generator is presented. This approach yields more accurate results for a low speed...
The paper proposes an adaptive sliding observer to accurately estimate the rotor position for a direct-drive permanent magnet synchronous generator (PMSG). Without any position sensor, the generator torque and flux responses retain high performance both in the steady state and during transients. The problem on the shaft encoder installation difficulty, reliability and disturbance in encoder cable...
This paper introduces the use of a three-phase matrix converter as an alternative to the DC-link back-to-back converter, for doubly-fed induction generator used in wind turbine system. A new dynamic model of matrix converter is proposed together with d-q dynamic representation of doubly fed induction generator. Consequently, the complicated three-phase coupling system is transformed into two independent...
This paper presents a current modulation scheme for matrix converter which serves as a power electronics interface in wound rotor induction generator based wind energy conversion system. It not only efficiently decouples active and reactive power of the generation system, but also gives a good grid connection performance. The proposed wind generation system is verified via simulation.
Conceptually, a micro-grids can operate in parallel with the main grid system to support the grid voltage or as an isolated system to support customers isolated from the grid. In islanding operations, the micro-grid can continue to supply power to the customers thereby increasing the reliability of the power system. In a micro-grid with a significant percentage of wind power, a reactive power source...
Using of the wind energy has become increasingly important as a renewable energy source and therefore is an increasing interest in exploiting it using a switched reluctance machine as a generator and optimize its characteristics in this domain. This work analyzes the generator mode of the switched reluctance machine in the direct coupling to the turbine shaft and coupled to the shaft through a gearbox.
This paper is concerned with modeling and simulation of a wind energy system with different topologies for the power converters, namely a matrix converter and a multilevel converter. We use pulse modulation by space vector modulation associated with sliding mode for controlling the converters, and we introduce power factor control at the output of the converters. Finally, we present the electric behavior...
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