scholarly journals Solve Coupled Axes Problem Without FOANR Based on Substitution Method to Control DFIG Used in Wind Application

2021 ◽  
Vol 54 (4) ◽  
pp. 623-631
Author(s):  
Bouir Abdesselam ◽  
Benoudjafer Cherif ◽  
Boughazi Othmane
Keyword(s):  
Nonlinear Model ◽  
Reactive Power ◽  
Complex Model ◽  
Open Loop ◽  
Substitution Method ◽  
Grid Voltage ◽  
Real Model ◽  
Novel Strategy ◽  
Doubly Fed ◽  
Rotor Side Converter

In order to control output powers generated by doubly fed induction generator (DFIG) used in wind application (WA) many previous studies, mainly based on flux orientation control (FOC) and neglecting resistance to get a simple model of DFIG with decoupled axis. However, this control strategy requires several hypotheses: low and stability of grid voltage in order to orientated the statoric flux, high power of generator to neglecting statoric resistance. As a result that may not be present in realty due to direct connection between stator and the grid In addition to the presence of resistance, whatever the power of the generator, therefore the DFIG represents a complex model and required a nonlinear control without previous approaches closer to reality to respond highly against DFIG nonlinear model, this is the first paper presents a novel strategy to control nonlinear model of DFIG based on substitution method to solving (d,q) coupled axes without flux orientation and neglecting resistance (FOANR) and also does not take into account stability of grid voltage, for produce required reference active and reactive power by controlling the voltage of rotor side converter (RSC), using classical proportional-integral (PI) controller in a non-linear synthesis form by three methods :direct control (D) and indirect open loop (IOL) and indirect with power loop (IWPL),we compared three controls and check their performance towards the real model of DFIG to verify our control and proving its effectiveness without previous approaches. Finally, the simulation results of the studied controls are presented, analyzed and compared.in terms of power reference tracking, robustness to the parametric variation and the ability to respond to sudden wind speed variation.

scholarly journals An Enhanced Low Voltage Ride-Through Control Scheme of a DIFG based WTG Using Crowbar and Braking Chopper

2021 ◽  
Vol 16 (1) ◽  
pp. 61-67
Author(s):  
Kishan Jayasawal ◽  
Khagendra Thapa
Keyword(s):  
Reactive Power ◽  
Low Voltage ◽  
Turbine Generator ◽  
Grid Voltage ◽  
Low Voltage Ride Through ◽  
Control Scheme ◽  
Safe Limit ◽  
Grid Codes ◽  
Doubly Fed ◽  
Rotor Side Converter

The grid codes define low voltage ride-through (LVRT) as capability of wind turbine generator (WTG) to support the grid voltage by injecting reactive power and suppress the rise of DC-link voltage and inrush rotor current in the rotor side converter (RSC) of the doubly fed induction generator (DFIG) during a fault. Moreover, the rotor current increases significantly during severe disturbances if any protection schemes are not employed. Therefore, the protection schemes must be used to avoid the damage to the converter during a fault. This paper proposes an enhanced LVRT control scheme of a DFIG employing a crowbar in the RSC side and braking chopper across the DC-link capacitor. The DFIG is highly delicate to grid voltage fluctuation during a fault because the DFIG is directly linked to the grid via stator. During severe fault the crowbar regulates the rotor current within an acceptable range and the braking chopper discharges the DC-link capacitor via resistor within a safe limit. The proposed LVRT control scheme is performed for a 2.4-MW DFIG using a MATLAB/SIMULINK simulator. The results delineate that the proposed control scheme is able to rapidly decrease the rotor current and repress the escalation in DC-link voltage during a grid fault.

A Novel Performance Enhancement Scheme for Doubly-Fed Induction Generator-Based Wind Power Systems under Voltage Sags and Swells

2017 ◽  
Vol 18 (4) ◽  
Author(s):  
Tapash Das ◽  
Jingxin Zhang ◽  
Hemanshu Pota
Keyword(s):  
Power Systems ◽  
Wind Power ◽  
Power Management ◽  
Reactive Power ◽  
Performance Enhancement ◽  
Protection System ◽  
Voltage Sags ◽  
Grid Voltage ◽  
Wind Power Systems ◽  
Doubly Fed

AbstractWind power is a major contributor in the renewable energy sector but it faces some issues regarding modern grid-code compliance. Popular wind power systems based on Doubly-Fed Induction Generators (DFIG) need additional protection under grid voltage disturbances. They also need to support the grid voltage under such transient occurrences. This paper presents a novel performance enhancement scheme for DFIGs subjected to symmetrical and asymmetrical voltage sags and swells at the Point of Common Coupling (PCC). The scheme comprises a protection system and a reactive power management system working simultaneously under the command of a supervisory control system. The protection system protects the DFIG converter by limiting the overcurrent in the Rotor Side Converter (RSC) of the DFIG and keeping the dc-link capacitor voltage within an acceptable range; whereas, the reactive power management supports the grid voltage by either injecting or absorbing reactive power to reduce the magnitude of voltage sags and swells. It is found that the performance of the DFIG wind generation system improves significantly under the proposed scheme. A grid-connected 9-MW DFIG wind farm is used for simulation in MATLAB/Simscape Power Systems.

scholarly journals Voltage Modulated DPC Strategy of DFIG Using Extended Power Theory under Unbalanced Grid Voltage Conditions

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6077
Author(s):  
Peng Cheng ◽  
Chao Wu ◽  
Fuwei Ning ◽  
Jing He
Keyword(s):  
Reactive Power ◽  
Active Power ◽  
Power Theory ◽  
Grid Voltage ◽  
Voltage Unbalance ◽  
Non Linear ◽  
Doubly Fed ◽  
Time Invariant ◽  
Unbalanced Grid ◽  
Extended Power

This paper develops a voltage modulated direct power control (VM-DPC) strategy of a doubly fed induction generator (DFIG) using extended power theory under unbalanced grid voltage conditions. By introducing the modulated voltage of the active and reactive powers and the non-linear VM controller, the proposed VM-DPC strategy enables the generator dynamics to change from the time-varying differential equations into the time-invariant ones. Then, in order to deal with the voltage unbalance, three available power feedbacks, a combination of real active power and extended reactive power, a combination of extended active power and real reactive power, a combination of extended active power and extended reactive power, are developed. Together with a conventional controller (PI + R and feedforwards) and a non-linear VM controller, the power feedbacks are well controlled to track their references with the achievement of the constant active power, the constant reactive power and the balanced stator current. The main advantage of the VM-DPC strategy is the introduction of the modulated voltage and the non-linear VM controller making the generator dynamics time-invariant, which is easy for applying various control methods. Furthermore, the application of extended power can avoid the sequence extractions and the power compensations under unbalanced grid voltage. Finally, the simulation results demonstrate the effectiveness of the developed VM-DPC strategy.

scholarly journals Approach Control of DFIG Rotor Side Converter Based on Grid Frequency Coordinated Control

2021 ◽  
Author(s):  
Zakieldeen M. E. Elhassan ◽  
Abusabah I. A. Ahmed ◽  
Othman Hassan Abdalla
Keyword(s):  
Case Studies ◽  
Reactive Power ◽  
Control Method ◽  
Coordinated Control ◽  
Wind Speeds ◽  
Speed Regulation ◽  
Doubly Fed ◽  
Grid Side ◽  
Rotor Side Converter ◽  
System Frequency

Abstract. This paper presents an approach frequency coordinated control of Doubly Fed Induction Generator (DFIG) applying in the Rotor Side Converter (RSC) using an order reference active power (Pref ). Pref is obtained from the frequency deviation, speed regulation and kinetic energy stored in the DIFG. The Pref is employed as a main controller parameter of the dq-axis currents in the RSC under two case studies. In case1 study, the Pref is used to regulate the q-axis reference current and the grid reactive power controlled d- axis reference current. Whilst in case2 study, the d- axis reference current is produced by Pref , and the rotormechanical speed responsible to generate the q-axis reference current. The modified vector control method is used to control the Grid Side Converter (GSC) in two case studies. The transient performance of two case studies is simulated by PSCAD/EMDTC program under constant, step and variable wind speeds. A comparative result between two case studies shown that the frequency coordinated control has an ability to control both rotor dq-axis currents, and it enhancing the system frequency as well as improved DFIG voltage stability.However, case2 study has a better response than case1 study during system operated under random wind speed.

The Transient Characteristics Analysis of Doubly-Fed Induction Generator during the Asymmetric Voltage Sag

2014 ◽  
Vol 644-650 ◽  
pp. 3509-3514
Author(s):  
Jian Hua Zhang ◽  
Hao Ran Shen ◽  
Lei Ding ◽  
Chun Lei Dai
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Voltage Drop ◽  
Voltage Sag ◽  
Grid Voltage ◽  
Low Voltage Ride Through ◽  
Double Frequency ◽  
Characteristics Analysis ◽  
Doubly Fed

In order to analyze the control strategy of the low voltage ride through (LVRT) of DFIG during the asymmetric voltage sag, it is necessary to analyze the transient performance of a DFIG during the asymmetric voltage sag. In this paper, analyzed the influence of the asymmetric grid voltage to DFIG and the analysis method of the asymmetric voltage sag, and on the basis of positive and negative sequence mathematical model, analyzed the composition of stator output active and reactive power under the condition of asymmetric grid voltage. And built a DFIG asymmetric voltage drop simulation model of 1.5MW in MATLAB/Simulink, the simulation results shows that the stator voltage, current, active power and reactive power all present a double frequency ripple during the asymmetric voltage sag, consistent with theoretical analysis. It can provide theoretical basis for double-fed motor control strategy of asymmetric LVRT.

scholarly journals DIRECT POWER CONTROL OF A DFIG BASED WIND TURBINS UNDER UNBALANCED GRID VOLTAGE WITHOUT ROTOR POSITION SENSOR

2017 ◽  
Vol 18 (1) ◽  
pp. 57-71
Author(s):  
Ali Izanlo ◽  
Asghar Gholamian ◽  
Mohammad Verij kazemi
Keyword(s):  
Doubly Fed Induction Generator ◽  
Position Sensor ◽  
Grid Voltage ◽  
Practical Applications ◽  
Rotor Position ◽  
Doubly Fed ◽  
The Cost ◽  
Rotor Side Converter ◽  
Unbalanced Grid ◽  
Position Sensorless

In this paper, the behavior of a doubly fed induction generator (DFIG) is proposed under unbalanced grid voltage and without using a rotor position sensor. There are two main methods that are been used for the detection of rotor position: using shaft sensor and sensorless algorithm. In this paper the shaft sensor is eliminated and a position sensorless algorithm is used for estimating the rotor position. Sensorless operation is more desirable than using shaft sensor, because the shaft sensor has several disadvantages related to the cost, cabling, robustness and maintenance. Also, during network unbalance, three selectable control targets are identified for the rotor side converter (RSC), i.e., obtaining sinusoidal and symmetrical stator currents, mitigation of active and reactive powers ripples and the cancellation of electromagnetic torque oscillations. The effectiveness of the proposed control strategy is confirmed by the simulation results from a 2-MW DFIG system. It is concluded that the sensorless algorithm is able to produce accurate results similar to the case of that used from shaft sensor and it can be used in the practical applications.

scholarly journals Vector Analysis and Optimal Control for the Voltage Regulation of a Weak Power System with Wind Energy and Power Electronics

2018 ◽  
Vol 10 (6) ◽  
pp. 1
Author(s):  
Nick Schinas
Keyword(s):  
Optimal Control ◽  
Reactive Power ◽  
Voltage Drop ◽  
Voltage Regulation ◽  
Induction Generators ◽  
Doubly Fed Induction Generators ◽  
Novel Strategy ◽  
Doubly Fed ◽  
Grid Side ◽  
Grid Side Converter

This paper deals with the voltage regulation in a weak system which contains large inductive loads and wind turbines using Doubly Fed Induction Generators (FDIGs). The DFIGs demand large amounts of reactive power from the grid and as a result, there is a voltage drop in the system which may be extra deteriorated if large inductive loads and motors are also present in the same line.  The problem of the voltage regulation in these cases is treated with the installation of a Static Var Compensator (SVC) besides the capability of the DFIGs to partially regulate the voltage themselves. In this paper, new modeling procedures based on optimal control are developed for the design of the SVC controller and a novel strategy for the grid side converter of the DFIG is presented. The nonlinear system is simulated in the SIMULINK software so that the performance of the new controllers is validated. 

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