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Wind energy is an unpredictable and fluctuating energy source. A nearly random wind speed and blade rotational turbulence can produce fluctuations in the output power and consequently voltage of the system. The output power of wind turbines fluctuates due to wind speed variations. This fluctuating power makes the wind power undispatchable, causing frequency deviations when wind power penetration is...
The paper describes the design of a Doubly Fed Induction Generator (DFIG) connected to the grid through back-to-back converters in the rotor circuit. A vector control oriented with the stator voltage is applied for the grid side converter that is responsible for maintaining the DC link voltage constant regardless of the power flow between the rotor and the grid. A field orientation control with the...
The rate at which large variable speed wind farms are being developed had increased rapidly as the demand for green energy has grown. With this increase in distributed energy penetration into power networks, the main focus must be on power quality (Voltage Quality and Supply Reliability). However, new grid codes require wind energy generating systems to ride through grid faults, and at the same time...
This paper proposes a simple technique to get maximum power of wind energy conversion system (WECS) without using sensors for wind and rotor speed of the permanent magnet synchronous generator (PMSG). It uses the measurements of DC current and DC voltage to obtain maximum power point tracking (MPPT) by controlling the duty cycle of the DC-DC boost converter switch. Moreover, a PI control is employed...
This paper proposes a hybrid AC/DC micro-grid which consists of an AC grid and a DC grid and operates in both grid-tied and autonomous mode. Wind turbine generators (WTGs), diesel generators (DGs) and conventional AC loads are connected to the AC grid whereas photovoltaic arrays with boost converter (PVBC), fuel cell generators and DC loads are tied to the DC grid. AC bus and DC bus are coupled through...
With worldwide increasing shares of electricity generated by wind energy converters, their influence on the mains stability and their reliable energy contribution becomes more and more relevant. The system management of wind energy converters has great influence on the power yield and the damping/amplification of wind caused power fluctuations. This paper compares the performance of different control...
This paper deals with the analysis, modeling, and control of a doubly-fed induction generator (DFIG) driven by the wind turbine. A control technique is presented for extracting the maximum power from the wind turbine. The wind energy conversion system (WECS) is equipped with a DFIG and two back-to-back connected voltage source converters (VSCs) in the rotor circuit. The proposed control technique...
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...
This paper deals with a new Autonomous Wind Energy Conversion System (AWECS) employing parallel operated Permanent Magnet Synchronous Generators (PMSGs) driven by variable speed wind turbines and feeding three-phase four-wire local loads. The proposed system utilizes three Pulse Width Modulated (PWM) Insulated Gate Bipolar Transistors (IGBTs) based voltage source converters (VSCs) with a battery energy...
The Doubly Fed Induction Generator (DFIG) is one of the most popular topologies applied in wind power systems. Its main advantage is to adjust the speed of a large system with much lower power converters. This is because its rotor side converter (RSC) operates under slip frequency and it needs only to support slip power to the overall system. However, this slip frequency is much lower than the grid...
This paper deals with a wind energy conversion system (WECS), based on a doubly fed induction generator (DFIG) and an electromechanical active power filter (APF). The objective is to respond simultaneously to electric energy requirement and power quality concerns. The proposed WECS is able not only to track the maximum power point of the wind energy but also to dampen harmonic currents from the grid...
This paper presents a method to calculate various losses in wind turbine generation system (WTGS) as a function of wind speed, which is based on the steady state analysis. Variable speed WTGS using a doubly-fed induction generator (DFIG) and power converters (inverter and converter) is mainly considered in this paper. By using the proposed method, wind turbine power, generated power, generator losses,...
A wind speed sensorless neural network (NN) based maximum power point tracking (MPPT) control algorithm for variable speed wind energy conversion system (WECS) is proposed. The proposed method is developed using Jordan type recurrent NN which is trained online using back-propagation. The algorithm, without requiring the knowledge of wind speed, air density or turbine parameters, generates at its output...
In this paper, the problem of tracking control for variable speed wind induction generator (IG) energy conversion system (WECS) is investigated using nonlinear predictive control. A rotor speed predictive control algorithm has been designed to control the angular speed of the machine in order to allow the WECS operate with maximum power extraction. The generator torque is estimated and injected into...
With increasing wind power in power systems, impact of wind generators on subsynchronous resonance (SSR) is of interest. Previous research has shown the impact of wind generation on SSR. In this paper, a control strategy is developed utilizing the power converters' control capability in a doubly fed induction generator (DFIG)-based wind turbine system. The control is realized through modulating the...
The efficiency of the wind power conversions systems can be greatly improved using an appropriate control algorithm. In this work, a robust control for variable speed wind power generation that incorporates a doubly feed induction generator is described. In the presented design it is applied the so called vector control theory. The proposed control scheme uses stator flux-oriented control for the...
Direct Torque Control (DTC) and Field Oriented Control (FOC) are the most dominant control strategies used in generators for wind turbines. In this paper both control methods were implemented on a Permanent Magnet Synchronous Generator (PMSG). The variable speed wind turbine with full scale power converter topology was chosen for design. Parameters from a 2 MW wind turbine were used for system modeling...
The speed of modern converter controlled wind turbines is almost completely decoupled from the grid frequency. Accordingly, wind turbines do not possess a natural response to frequency excursions. In this paper three different control concepts that enable wind turbines to participate on grid frequency control are introduced. The first uses pitch control together with the provision of reserve capacity...
With the increasing of wind penetration in power systems, many national grid codes demand complete models and simulation studies under different system conditions in order to ensure that the connection of a wind farm would not have a detrimental impact on the grid. It is now recognized that doubly fed induction generators (DFIG) are used in many large farms. A systematic control methodology for connection...
A sensorless control strategy for a permanent magnet synchronous generator (PMSG) in variable speed wind energy conversion system (WECS) is proposed. The proposed method is based on recursive least square estimation (RLSE) algorithm for rotor speed estimation using an equation containing only stator flux and current. Further, rotor position information used for coordinate transformation is computed...
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