This document summarizes a research paper that investigates improving the dynamic responses of grid-connected permanent magnet synchronous generator (PMSG) wind turbines using a fuzzy logic controller (FLC). The paper proposes using an FLC to control the pitch angle of the turbine blades based on wind speed and active power inputs. This allows for faster response compared to prior methods, leading to smoother power output and preventing mechanical damage. The system is modeled and simulated in Matlab/Simulink. Results show the FLC approach effectively regulates turbine output power under varying wind speeds and load conditions.
Nowadays, the fossil combustibles are replaced by renewable energies sources .These renewable energies are nontoxic, dirt free, and protected and reasonably cheep for the user. Renewable energy resources like bio-gas, geothermal, solar, tidal waves and wind have been found as the best alternatives energy source. Among those renewable energy sources, wind energy stands foremost for generating electricity. In order to have a constant utilization of wind energy and to extract maximum power from wind energy. In this paper, various control strategies prevalent to both the Doubly Fed Induction Generator (DFIG)and Permanent Magnet Synchronous Generator(PMSG) have been analyzed . In addition, control topology applicable to power electronics converter/inverter used in wind electric generators are discussed.
A Performance Comparison of DFIG using Power Transfer Matrix and Direct Power...IAES-IJPEDS
This paper presents a direct power control and power transfer matrix model for a doubly-fed induction generator (DFIG) wind energy system (WES). Control of DFIG wind turbine system is traditionally based on either stator- flux-oriented or stator-voltage-oriented vector control. The performance of Direct Power Control (DPC) and Power transfer Matrix control for the same wind speed are studied. The Power transfer matrix Control gave better results. The validity and performance of the proposed modelling and control approaches are investigated using a study system consisting of a grid connected DFIG WES. The performance of DFIG with Power Transfer Matrix and Direct Power Control (DPC) techniques are obtained through simulation. The time domain simulation of the study system using MATLAB Simulink is carried out. The results obtained in the two cases are compared.
Flux Based Sensorless Speed Sensing and Real and Reactive Power Flow Control ...ijeei-iaes
This aim of this paper is to design controller for Doubly Fed Induction Generator (DFIG) converters and MPPT for turbine and a sensor-less rotor speed estimation to maintain equilibrium in rotor speed, generator torque, and stator and rotor voltages. It is also aimed to meet desired reference real and reactive power during the turbulences like sudden change in reactive power or voltage with concurrently changing wind speed. The turbine blade angle changes with variations in wind speed and direction of wind flow and improves the coefficient of power extracted from turbine using MPPT. Rotor side converter (RSC) helps to achieve optimal real and reactive power from generator, which keeps rotor to rotate at optimal speed and to vary current flow from rotor and stator terminals. Rotor speed is estimated using stator and rotor flux estimation algorithm. Parameters like tip speed ratio; coefficient of power, stator and rotor voltage, current, real, reactive power; rotor speed and electromagnetic torque are studied using MATLAB simulation. The performance of DFIG is compared when there is in wind speed change only; alter in reactive power and variation in grid voltage individually along with variation in wind speed.
Novel Adaptive Controller for PMSG Driven Wind Turbine To Improve Power Syste...IJMERJOURNAL
ABSTRACT: This paper describes the behavior of a permanent magnet synchronous generator (PMSG) driven by wind turbine. The proposed conversion system is a good alternative due to its high efficiency and reliability. Electrolytic capacitors are not required in this type of converter and the voltage in the DC-link as well as the generated reactive power can be dynamically modified according to the wind velocity. The adaptive control strategy uses an adaptive PI which is self-tuned based on a linear approximation of the power system calculated at each sample time. Space vector technique for grid side inverter for transformer less integration of generator and a pulse-width modulated current source converter. A model reference is also projected in order to reduce the post-fault voltages. Simulation results prove the advantages of the proposed control. A MATLAB computer simulation study was undertaken and results on PWM-CSC are presented
A Lyapunov Based Approach to Enchance Wind Turbine Stabilityijeei-iaes
This paper introduces a nonlinear control of a wind turbine based on a Double Feed Induction Generator. The Rotor Side converter is controlled by using field oriented control and Backstepping strategy to enhance the dynamic stability response. The Grid Side converter is controlled by a sliding mode. These methods aim to increase dynamic system stability for variable wind speed. Hence, The Doubly Fed Induction Generator (DFIG) is studied in order to illustrate its behavior in case of severe disturbance, and its dynamic response in grid connected mode for variable speed wind operation. The model is presented and simulated under Matlab/ Simulink.
Indirect power control of DFIG based on wind turbine operating in MPPT using ...IJECEIAES
This paper describes a MPPT control of the stator powers of a DFIG operating within a wind energy system using the backstepping control technique. The objective of this work consists of providing a robust control to the rotor-side converter allowing the stator active power to be regulated at the maximum power extracted from the wind turbine, as well as maintaining the stator reactive power at zero to maintain the power factor at unity, under various conditions. We have used the Matlab/Simulink platform to model the wind system based on a 7.5 kW DFIG and to implement the MPPT control algorithm in a first step, then we have implemented the field-oriented control and the backstepping controller in a second step. The simulation results obtained were very satisfactory with a fast transient response and neglected power ripples. They furthermore confirmed the high robustness of the approach used in dealing with the variation of the internal parameters of the machine.
Nowadays, the fossil combustibles are replaced by renewable energies sources .These renewable energies are nontoxic, dirt free, and protected and reasonably cheep for the user. Renewable energy resources like bio-gas, geothermal, solar, tidal waves and wind have been found as the best alternatives energy source. Among those renewable energy sources, wind energy stands foremost for generating electricity. In order to have a constant utilization of wind energy and to extract maximum power from wind energy. In this paper, various control strategies prevalent to both the Doubly Fed Induction Generator (DFIG)and Permanent Magnet Synchronous Generator(PMSG) have been analyzed . In addition, control topology applicable to power electronics converter/inverter used in wind electric generators are discussed.
A Performance Comparison of DFIG using Power Transfer Matrix and Direct Power...IAES-IJPEDS
This paper presents a direct power control and power transfer matrix model for a doubly-fed induction generator (DFIG) wind energy system (WES). Control of DFIG wind turbine system is traditionally based on either stator- flux-oriented or stator-voltage-oriented vector control. The performance of Direct Power Control (DPC) and Power transfer Matrix control for the same wind speed are studied. The Power transfer matrix Control gave better results. The validity and performance of the proposed modelling and control approaches are investigated using a study system consisting of a grid connected DFIG WES. The performance of DFIG with Power Transfer Matrix and Direct Power Control (DPC) techniques are obtained through simulation. The time domain simulation of the study system using MATLAB Simulink is carried out. The results obtained in the two cases are compared.
Flux Based Sensorless Speed Sensing and Real and Reactive Power Flow Control ...ijeei-iaes
This aim of this paper is to design controller for Doubly Fed Induction Generator (DFIG) converters and MPPT for turbine and a sensor-less rotor speed estimation to maintain equilibrium in rotor speed, generator torque, and stator and rotor voltages. It is also aimed to meet desired reference real and reactive power during the turbulences like sudden change in reactive power or voltage with concurrently changing wind speed. The turbine blade angle changes with variations in wind speed and direction of wind flow and improves the coefficient of power extracted from turbine using MPPT. Rotor side converter (RSC) helps to achieve optimal real and reactive power from generator, which keeps rotor to rotate at optimal speed and to vary current flow from rotor and stator terminals. Rotor speed is estimated using stator and rotor flux estimation algorithm. Parameters like tip speed ratio; coefficient of power, stator and rotor voltage, current, real, reactive power; rotor speed and electromagnetic torque are studied using MATLAB simulation. The performance of DFIG is compared when there is in wind speed change only; alter in reactive power and variation in grid voltage individually along with variation in wind speed.
Novel Adaptive Controller for PMSG Driven Wind Turbine To Improve Power Syste...IJMERJOURNAL
ABSTRACT: This paper describes the behavior of a permanent magnet synchronous generator (PMSG) driven by wind turbine. The proposed conversion system is a good alternative due to its high efficiency and reliability. Electrolytic capacitors are not required in this type of converter and the voltage in the DC-link as well as the generated reactive power can be dynamically modified according to the wind velocity. The adaptive control strategy uses an adaptive PI which is self-tuned based on a linear approximation of the power system calculated at each sample time. Space vector technique for grid side inverter for transformer less integration of generator and a pulse-width modulated current source converter. A model reference is also projected in order to reduce the post-fault voltages. Simulation results prove the advantages of the proposed control. A MATLAB computer simulation study was undertaken and results on PWM-CSC are presented
A Lyapunov Based Approach to Enchance Wind Turbine Stabilityijeei-iaes
This paper introduces a nonlinear control of a wind turbine based on a Double Feed Induction Generator. The Rotor Side converter is controlled by using field oriented control and Backstepping strategy to enhance the dynamic stability response. The Grid Side converter is controlled by a sliding mode. These methods aim to increase dynamic system stability for variable wind speed. Hence, The Doubly Fed Induction Generator (DFIG) is studied in order to illustrate its behavior in case of severe disturbance, and its dynamic response in grid connected mode for variable speed wind operation. The model is presented and simulated under Matlab/ Simulink.
Indirect power control of DFIG based on wind turbine operating in MPPT using ...IJECEIAES
This paper describes a MPPT control of the stator powers of a DFIG operating within a wind energy system using the backstepping control technique. The objective of this work consists of providing a robust control to the rotor-side converter allowing the stator active power to be regulated at the maximum power extracted from the wind turbine, as well as maintaining the stator reactive power at zero to maintain the power factor at unity, under various conditions. We have used the Matlab/Simulink platform to model the wind system based on a 7.5 kW DFIG and to implement the MPPT control algorithm in a first step, then we have implemented the field-oriented control and the backstepping controller in a second step. The simulation results obtained were very satisfactory with a fast transient response and neglected power ripples. They furthermore confirmed the high robustness of the approach used in dealing with the variation of the internal parameters of the machine.
The paper proposes a complete modeling and control technique of variable speed wind turbine system (WTS) based on the doubly fed induction generator (DFIG). Two levels back-to-back converter is used to ensure the energy transfer between the DFIG rotor and the grid. The wind turbine to operate efficiently, a maximum power point tracking (MPPT) algorithm is implemented. Then, direct power control (DPC) strategy has been combined with the MPPT technique in order to guarantee the selection of the appropriate rotor voltage vectors and to minimize the active and reactive power errors. Finally, the simulation is performed by using MATLAB/simulink platform basing on 7.5KW DFIG wind generation system, and the results prove the effectiveness of our proposed control technique.
The following article presents the control of the power generated by the Doubly Fed Induction Generator, integrated into the wind system, whose rotor is linked to the power converters (Rotor Side Convert (RSC) and Grid Side Converter (GSC)) interfaced by the DC-BUS and connected to the grid via a filter (Rf, Lf) in order to obtain an optimal power to the grid and to ensure system stability. The objective of this study is to understand and to make the comparison between Sliding mode Control technique and the Flux Oriented Control in order to control the Doubly Fed Induction Generator powers exchanged with the grid, it also aims at maintaining the DC-BUS voltage constant and a unit power factor at the grid connection point.The results of simulation show the performance of the Sliding mode Control in terms of monitoring, and robustness with regard to the parametric variations, compared to the Flux Oriented Control. The performance of the systems was tested and compared with the use of MATLAB/Simulink software.
In this paper, an adaptive anti-windup control strategy for permanent magnet synchronous generator dedicated for wind energy conversion systems. The proposed control has the advantage to suppress the performance deterioration caused by the overshooting phenomenon, and optimize the controller gains using the particle swarm optimization algorithm. The scheme of the speed controller is implemented on field orientation control in the generator side converter. A simulation of the proposed scheme is carried out in SIMULINK-MATLAB in order to evaluate the effectiveness of the control against the saturation and the parameter optimization.
Performance analysis of various parameters by comparison of conventional pitc...eSAT Journals
Abstract This paper deals with a variable speed wind turbine coupled with a permanent magnet synchronous generator connected through a two mass drive train. This drive train is connected to synchronous generator and after the conversion process finally connected to grid and the idea of transmission over a long distance makes the use of converter necessary and at the receiving end. The inverter is used to convert it back and the inverter is designed with a proper gate signal to get the best output three phase voltages. The fuzzy logic controller is used to track generator speed with varying wind speed to optimize turbine aerodynamic efficiency in the outer speed loop. Pitch angle control of wind turbine has been used widely to reduce torque and output power variation in high rated wind speed areas .The machine side converter is designed to extract maximum power from the wind. In this work a WECS connected with grid is designed in Matlab and a Fuzzy controller is designed to improve the output and we can see the major difference in DC link voltage and reactive power in transmission line. From the outputs we can also go through the reactive power issue which system is best for inductive load or capacitive load. The simple PI system is good for capacitive load and the fuzzy system is better option for the inductive load. The results of both the system of normal controller and fuzzy controller is compared and analyzed. Key Words: Fuzzy logic controller (FLC), permanent magnet synchronous generator (PMSG), insulated gate bipolar transistor (IGBT) , Pulse width modulation (PWM), Wind energy conversion system, DC link capacitor. FACTS Flexible A.C Transmission system, PI proportional integral
Performance analysis of various parameters by comparison of conventional pitc...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
PSO-Backstepping controller of a grid connected DFIG based wind turbine IJECEIAES
The paper demonstrates the feasibility of an optimal backstepping controller for doubly fed induction generator based wind turbine (DFIG). The main purpose is the extract of maximum energy and the control of active and reactive power exchanged between the generator and electrical grid in presence of uncertainty. The maximum energy is obtained by applying an algorithm based on artificial bee colony approach. Particle swarm optimization is used to select optimal value of backstepping’s parameters. The simulation is carried out on 2.4 MW DFIG based wind turbine system. The optimized performance of the proposed control technique under uncertainty parameters is established by simulation results.
In this work, we are interested in improving the performance of a doubly-fed induction generator (DFIG)-based wind system, by applying a sliding mode control strategy. The objective is the regulation of the active and reactive power, also the voltage and the frequency of the signal injected into the distribution network. The model proposed for the control is based on the sliding mode technique with performance estimators. The proposed model was validated by a simulation on MATLAB/Simulink.
Load Frequency Control of DFIG-isolated and Grid Connected ModeIJAPEJOURNAL
Wind energy is one of the extraordinary promising sources of renewable energy due to its clean character, free availability and economic viability. A Doubly Fed Induction Generator (DFIG) feeds power from both the stator and the rotor windings at speeds above synchronous speed of the machine. This paper deals the load frequency control of doubly fed induction generator in isolated mode and grid connected mode. The wind turbine model is obtained using MATLAB/ SIMULINK which consists of DFIG, rotor side rectifier, grid side inverter and grid. This model is controlled by conventional controllerand proposed Load Frequency Control (LFC) method. The results are proven that frequency control gives better results in all the aspects
PI and LQR controllers for Frequency Regulation including Wind GenerationIJECEIAES
The increasing use of renewable technologies such as wind turbines in power systems may require the contribution of these new sources into grid ancillary services, such as Load Frequency Control. Hence, this work dealt with the performance comparison of two traditional control structures, PI and LQR, for secondary regulation of Load Frequency Control with the participation of variable-speed wind turbines. For this purpose, the doubly-fed induction generator wind turbine was modeled with additional control loops for emulation of the inertial response of conventional machines for frequency regulation tasks. Performance of proposed strategies was verified through simulation in a benchmark adapted from the WSCC 3 machines 9-bus test system. Results showed overall superior performance for LQR controller, although requiring more strenuous control effort from conventional units than PI control.
Intelligent Control for Doubly Fed Induction Generator Connected to the Elect...IJPEDS-IAES
In this paper we are interested in optimizing the wind power capture, using the Doubly Fed Induction Generator (DFIG). This machine is preferred to other types of variable speed generator because of their advantages in economic terms and control. The Artificial Neural Network (ANN) based on Direct Torque Control (DTC) which is used to control the electromagnetic torque in order to extract the maximum power. The main objective of this intelligent technique is to replace the conventional switching table by a voltage selector based on (ANN) to reduce torque and flux ripples. Moreover, the fuzzy logic controller is used to grid side converter to keep DC link voltage constant, and also to achieve unity power factor operation. The main advantage of the two control strategies proposed in this paper is that they are not influenced by the variation of the machine parameter. The pitch control is also presented to limit the generator power at its rated value. Simulation results of 1,5 MW, for (DFIG) based Wind Energy Conversion System (WECS) confirm the effectiveness and the performance of the global proposed approaches.
Control of the powerquality for a DFIG powered by multilevel inverters IJECEIAES
This paper treats the modeling, and the control of a wind power system based on a doubly fed induction generator DFIG, the stator is directly connected to the grid, while the rotor is powered by multilevel inverters. In order to get a decoupled system of controlfor an independently transits of active and reactive power, a vector control method based on stator flux orientation SFOC is considered: Direct vector control based on PI controllers. Cascaded H-bridge CHBI multilevel inverters are used in the rotor circuit to study its effect on supply power quality. All simulation models are built in MATLAB/Simulink software. Results and waveforms clearly show the effectiveness of vector control strategy. Finally, performances of the system will tested and compared for each levels of inverter.
Wind Energy Conversion Based On Matrix ConverterIAES-IJPEDS
In recent years renewable sources such as solar, wave and wind are used for the generation of electricity. Wind is one of the major renewable sources. The amount of energy from a Wind Energy Conversion System (WECS) depends not only on the wind at the site, but also on the control strategy used for the WECS. In assistance to get the appropriate wind energy from the conversion system, wind turbine generator will be run in variable speed mode. The variable speed capability is achieved through the use of an advanced power electronic converter. Fixed speed wind turbines and induction generators are often used in wind farms. But the limitations of such generators are low efficiency and poor power quality which necessitates the variable speed wind turbine generators such as Doubly Fed Induction Generator (DFIG) and Permanent Magnet Synchronous Generator (PMSG). A high-performance configuration can be obtained by using a PMSG and a converter in combination AC-DC-AC connect between stator & rotor points for providing the required variable speed operation.
A novel optimum tip speed ratio control of low speed wind turbine generator b...journalBEEI
Variable speed control of wind turbine generator systems have been developed to get maximum output power at every wind speed variation, also called Maximum Power Points Tracking (MPPT). Generally, MPPT control system consists of MPPT algorithm to track the controller reference and generator speed controller. In this paper, MPPT control system is proposed for low speed wind turbine generator systems (WTGs) with MPPT algorithms based on optimum tip speed ratio (TSR) and generator speed controller based on field oriented control using type-2 fuzzy system (T2FS). The WTGs are designed using horizontal axis wind turbines to drive permanent magnet synchronous generators (PMSG). The simulation show that the MPPT system based optimum TSR has been able to control the generator output power around the maximum point at all wind speeds.
This article addresses the problem of controlling an overall wind energy conversion system (WECS) formed by a wind turbine connected to the grid via a doubly fed introduction generator (DFIG) and an AC/DC/AC converter. The main control objectives are fourfold: (i) designing an output feedback speed controller that makes the DFIG rotate at the optimal value delivered by the MPPT strategy, (ii) controlling the stator reactive power so as to be null, (iii) guaranteeing the DC-link voltage in the grid side converter to be at a given constant value, (iv) ensuring a unitary power factor. A high gain observer is synthesized, in order to provide estimated values of the mechanical variables. To achieve the control objectives, a sliding mode controller involving the mechanical observer is designed. The performance of the system configuration based on the 2MW-DFIG with the proposed controller is evaluated by a numerical simulation under a realistic wind profile using MATLAB/SIMULINK/SimPowerSystems environment.
Integration of a Wind Turbine Based Doubly Fed Induction Generator Using STAT...IJERA Editor
Wind power stations mostly placed in remote areas; so they are characterized by weak grids and are often submitted to power system disturbance like faults, voltage sag etc. In this paper the crowbar protection method is used to ride through voltage sags and STATCOM is used to quickly sense the voltage sag and overcome it. The behavior of these machines during grid failure is an important issue. DFIG consists of a common induction generator with slip ring and a partial scale power electronic converter. Indirect field oriented controller is applied to rotor side converter for active power control and voltage regulation of wind turbine. On grid side PQ control scheme is applied. Wind turbine and its control units are described in details and also for STATCOM control. All power system components are simulated in MATLAB/ SIMULINK software. For studying the performance of controller, different abnormal conditions are applied even the worst case. Simulation results prove that the performance of STATCOM and DFIG control schemes as improving power quality and stability of wind turbine.
Statcom for improved dynamic performance of wind farms in power gridAsoka Technologies
Application of FACTS controller called Static Synchronous Compensator STATCOM to improve the performance of power grid with Wind Farms is investigated .The essential feature of the STATCOM is that it has the ability to absorb or inject fastly the reactive power with power grid . Therefore the voltage regulation of the power grid with STATCOM FACTS device is achieved. Moreover restoring the stability of the power system having wind farm after occurring
severe disturbance such as faults or wind farm mechanical power variation is obtained with STATCOM controller . The dynamic model of the power system having wind farm controlled by
proposed STATCOM is developed . To Validate the powerful of the STATCOM FACTS controller , the studied power system is simulated and subjected to different severe disturbances . The results prove the effectiveness of the proposed STATCOM controller in terms of fast damping the power system oscillations and restoring the power system stability .
DYNAMIC STABILITY ENHANCEMENT IN MULTIMACHINE POWER SYSTEMS BY DIFFERENT FACT...IAEME Publication
Modern Power system are becoming increasingly stressed due to increasing demand of electricity and restriction on new transmission network .This effect of power network is that transmission power loss increases and decreasing power transmission capability of network. And also stability of synchronous alternator is lost. There are electronic based FACTS (Flexible AC Transmission system) devises is established to enhance the power transmitting capacity. A major important function of FACTS devises is to enhanced power transmission capacity of power system network without increasing power generation capacity of power system. Because system voltage is inversely proportional to transmission loses.
The paper proposes a complete modeling and control technique of variable speed wind turbine system (WTS) based on the doubly fed induction generator (DFIG). Two levels back-to-back converter is used to ensure the energy transfer between the DFIG rotor and the grid. The wind turbine to operate efficiently, a maximum power point tracking (MPPT) algorithm is implemented. Then, direct power control (DPC) strategy has been combined with the MPPT technique in order to guarantee the selection of the appropriate rotor voltage vectors and to minimize the active and reactive power errors. Finally, the simulation is performed by using MATLAB/simulink platform basing on 7.5KW DFIG wind generation system, and the results prove the effectiveness of our proposed control technique.
The following article presents the control of the power generated by the Doubly Fed Induction Generator, integrated into the wind system, whose rotor is linked to the power converters (Rotor Side Convert (RSC) and Grid Side Converter (GSC)) interfaced by the DC-BUS and connected to the grid via a filter (Rf, Lf) in order to obtain an optimal power to the grid and to ensure system stability. The objective of this study is to understand and to make the comparison between Sliding mode Control technique and the Flux Oriented Control in order to control the Doubly Fed Induction Generator powers exchanged with the grid, it also aims at maintaining the DC-BUS voltage constant and a unit power factor at the grid connection point.The results of simulation show the performance of the Sliding mode Control in terms of monitoring, and robustness with regard to the parametric variations, compared to the Flux Oriented Control. The performance of the systems was tested and compared with the use of MATLAB/Simulink software.
In this paper, an adaptive anti-windup control strategy for permanent magnet synchronous generator dedicated for wind energy conversion systems. The proposed control has the advantage to suppress the performance deterioration caused by the overshooting phenomenon, and optimize the controller gains using the particle swarm optimization algorithm. The scheme of the speed controller is implemented on field orientation control in the generator side converter. A simulation of the proposed scheme is carried out in SIMULINK-MATLAB in order to evaluate the effectiveness of the control against the saturation and the parameter optimization.
Performance analysis of various parameters by comparison of conventional pitc...eSAT Journals
Abstract This paper deals with a variable speed wind turbine coupled with a permanent magnet synchronous generator connected through a two mass drive train. This drive train is connected to synchronous generator and after the conversion process finally connected to grid and the idea of transmission over a long distance makes the use of converter necessary and at the receiving end. The inverter is used to convert it back and the inverter is designed with a proper gate signal to get the best output three phase voltages. The fuzzy logic controller is used to track generator speed with varying wind speed to optimize turbine aerodynamic efficiency in the outer speed loop. Pitch angle control of wind turbine has been used widely to reduce torque and output power variation in high rated wind speed areas .The machine side converter is designed to extract maximum power from the wind. In this work a WECS connected with grid is designed in Matlab and a Fuzzy controller is designed to improve the output and we can see the major difference in DC link voltage and reactive power in transmission line. From the outputs we can also go through the reactive power issue which system is best for inductive load or capacitive load. The simple PI system is good for capacitive load and the fuzzy system is better option for the inductive load. The results of both the system of normal controller and fuzzy controller is compared and analyzed. Key Words: Fuzzy logic controller (FLC), permanent magnet synchronous generator (PMSG), insulated gate bipolar transistor (IGBT) , Pulse width modulation (PWM), Wind energy conversion system, DC link capacitor. FACTS Flexible A.C Transmission system, PI proportional integral
Performance analysis of various parameters by comparison of conventional pitc...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
PSO-Backstepping controller of a grid connected DFIG based wind turbine IJECEIAES
The paper demonstrates the feasibility of an optimal backstepping controller for doubly fed induction generator based wind turbine (DFIG). The main purpose is the extract of maximum energy and the control of active and reactive power exchanged between the generator and electrical grid in presence of uncertainty. The maximum energy is obtained by applying an algorithm based on artificial bee colony approach. Particle swarm optimization is used to select optimal value of backstepping’s parameters. The simulation is carried out on 2.4 MW DFIG based wind turbine system. The optimized performance of the proposed control technique under uncertainty parameters is established by simulation results.
In this work, we are interested in improving the performance of a doubly-fed induction generator (DFIG)-based wind system, by applying a sliding mode control strategy. The objective is the regulation of the active and reactive power, also the voltage and the frequency of the signal injected into the distribution network. The model proposed for the control is based on the sliding mode technique with performance estimators. The proposed model was validated by a simulation on MATLAB/Simulink.
Load Frequency Control of DFIG-isolated and Grid Connected ModeIJAPEJOURNAL
Wind energy is one of the extraordinary promising sources of renewable energy due to its clean character, free availability and economic viability. A Doubly Fed Induction Generator (DFIG) feeds power from both the stator and the rotor windings at speeds above synchronous speed of the machine. This paper deals the load frequency control of doubly fed induction generator in isolated mode and grid connected mode. The wind turbine model is obtained using MATLAB/ SIMULINK which consists of DFIG, rotor side rectifier, grid side inverter and grid. This model is controlled by conventional controllerand proposed Load Frequency Control (LFC) method. The results are proven that frequency control gives better results in all the aspects
PI and LQR controllers for Frequency Regulation including Wind GenerationIJECEIAES
The increasing use of renewable technologies such as wind turbines in power systems may require the contribution of these new sources into grid ancillary services, such as Load Frequency Control. Hence, this work dealt with the performance comparison of two traditional control structures, PI and LQR, for secondary regulation of Load Frequency Control with the participation of variable-speed wind turbines. For this purpose, the doubly-fed induction generator wind turbine was modeled with additional control loops for emulation of the inertial response of conventional machines for frequency regulation tasks. Performance of proposed strategies was verified through simulation in a benchmark adapted from the WSCC 3 machines 9-bus test system. Results showed overall superior performance for LQR controller, although requiring more strenuous control effort from conventional units than PI control.
Intelligent Control for Doubly Fed Induction Generator Connected to the Elect...IJPEDS-IAES
In this paper we are interested in optimizing the wind power capture, using the Doubly Fed Induction Generator (DFIG). This machine is preferred to other types of variable speed generator because of their advantages in economic terms and control. The Artificial Neural Network (ANN) based on Direct Torque Control (DTC) which is used to control the electromagnetic torque in order to extract the maximum power. The main objective of this intelligent technique is to replace the conventional switching table by a voltage selector based on (ANN) to reduce torque and flux ripples. Moreover, the fuzzy logic controller is used to grid side converter to keep DC link voltage constant, and also to achieve unity power factor operation. The main advantage of the two control strategies proposed in this paper is that they are not influenced by the variation of the machine parameter. The pitch control is also presented to limit the generator power at its rated value. Simulation results of 1,5 MW, for (DFIG) based Wind Energy Conversion System (WECS) confirm the effectiveness and the performance of the global proposed approaches.
Control of the powerquality for a DFIG powered by multilevel inverters IJECEIAES
This paper treats the modeling, and the control of a wind power system based on a doubly fed induction generator DFIG, the stator is directly connected to the grid, while the rotor is powered by multilevel inverters. In order to get a decoupled system of controlfor an independently transits of active and reactive power, a vector control method based on stator flux orientation SFOC is considered: Direct vector control based on PI controllers. Cascaded H-bridge CHBI multilevel inverters are used in the rotor circuit to study its effect on supply power quality. All simulation models are built in MATLAB/Simulink software. Results and waveforms clearly show the effectiveness of vector control strategy. Finally, performances of the system will tested and compared for each levels of inverter.
Wind Energy Conversion Based On Matrix ConverterIAES-IJPEDS
In recent years renewable sources such as solar, wave and wind are used for the generation of electricity. Wind is one of the major renewable sources. The amount of energy from a Wind Energy Conversion System (WECS) depends not only on the wind at the site, but also on the control strategy used for the WECS. In assistance to get the appropriate wind energy from the conversion system, wind turbine generator will be run in variable speed mode. The variable speed capability is achieved through the use of an advanced power electronic converter. Fixed speed wind turbines and induction generators are often used in wind farms. But the limitations of such generators are low efficiency and poor power quality which necessitates the variable speed wind turbine generators such as Doubly Fed Induction Generator (DFIG) and Permanent Magnet Synchronous Generator (PMSG). A high-performance configuration can be obtained by using a PMSG and a converter in combination AC-DC-AC connect between stator & rotor points for providing the required variable speed operation.
A novel optimum tip speed ratio control of low speed wind turbine generator b...journalBEEI
Variable speed control of wind turbine generator systems have been developed to get maximum output power at every wind speed variation, also called Maximum Power Points Tracking (MPPT). Generally, MPPT control system consists of MPPT algorithm to track the controller reference and generator speed controller. In this paper, MPPT control system is proposed for low speed wind turbine generator systems (WTGs) with MPPT algorithms based on optimum tip speed ratio (TSR) and generator speed controller based on field oriented control using type-2 fuzzy system (T2FS). The WTGs are designed using horizontal axis wind turbines to drive permanent magnet synchronous generators (PMSG). The simulation show that the MPPT system based optimum TSR has been able to control the generator output power around the maximum point at all wind speeds.
This article addresses the problem of controlling an overall wind energy conversion system (WECS) formed by a wind turbine connected to the grid via a doubly fed introduction generator (DFIG) and an AC/DC/AC converter. The main control objectives are fourfold: (i) designing an output feedback speed controller that makes the DFIG rotate at the optimal value delivered by the MPPT strategy, (ii) controlling the stator reactive power so as to be null, (iii) guaranteeing the DC-link voltage in the grid side converter to be at a given constant value, (iv) ensuring a unitary power factor. A high gain observer is synthesized, in order to provide estimated values of the mechanical variables. To achieve the control objectives, a sliding mode controller involving the mechanical observer is designed. The performance of the system configuration based on the 2MW-DFIG with the proposed controller is evaluated by a numerical simulation under a realistic wind profile using MATLAB/SIMULINK/SimPowerSystems environment.
Integration of a Wind Turbine Based Doubly Fed Induction Generator Using STAT...IJERA Editor
Wind power stations mostly placed in remote areas; so they are characterized by weak grids and are often submitted to power system disturbance like faults, voltage sag etc. In this paper the crowbar protection method is used to ride through voltage sags and STATCOM is used to quickly sense the voltage sag and overcome it. The behavior of these machines during grid failure is an important issue. DFIG consists of a common induction generator with slip ring and a partial scale power electronic converter. Indirect field oriented controller is applied to rotor side converter for active power control and voltage regulation of wind turbine. On grid side PQ control scheme is applied. Wind turbine and its control units are described in details and also for STATCOM control. All power system components are simulated in MATLAB/ SIMULINK software. For studying the performance of controller, different abnormal conditions are applied even the worst case. Simulation results prove that the performance of STATCOM and DFIG control schemes as improving power quality and stability of wind turbine.
Statcom for improved dynamic performance of wind farms in power gridAsoka Technologies
Application of FACTS controller called Static Synchronous Compensator STATCOM to improve the performance of power grid with Wind Farms is investigated .The essential feature of the STATCOM is that it has the ability to absorb or inject fastly the reactive power with power grid . Therefore the voltage regulation of the power grid with STATCOM FACTS device is achieved. Moreover restoring the stability of the power system having wind farm after occurring
severe disturbance such as faults or wind farm mechanical power variation is obtained with STATCOM controller . The dynamic model of the power system having wind farm controlled by
proposed STATCOM is developed . To Validate the powerful of the STATCOM FACTS controller , the studied power system is simulated and subjected to different severe disturbances . The results prove the effectiveness of the proposed STATCOM controller in terms of fast damping the power system oscillations and restoring the power system stability .
DYNAMIC STABILITY ENHANCEMENT IN MULTIMACHINE POWER SYSTEMS BY DIFFERENT FACT...IAEME Publication
Modern Power system are becoming increasingly stressed due to increasing demand of electricity and restriction on new transmission network .This effect of power network is that transmission power loss increases and decreasing power transmission capability of network. And also stability of synchronous alternator is lost. There are electronic based FACTS (Flexible AC Transmission system) devises is established to enhance the power transmitting capacity. A major important function of FACTS devises is to enhanced power transmission capacity of power system network without increasing power generation capacity of power system. Because system voltage is inversely proportional to transmission loses.
This paper proposes a feedback linearization control of doubly fed induction generator based wind energy systems for improving decoupled control of the active and reactive powers stator. In order to enhance dynamic performance of the controller studied, the adopted control is reinforced by a fuzzy logic controller. This approach is designed without any model of rotor flux estimation. The difficulty of measuring of rotor flux is overcome by using high gain observer. The stability of the nonlinear observer is proved by the Lyapunov theory. Numerical simulations using MATLAB-SIMULINK shown clearly the robustness of the proposed control, particularly to the disturbance rejection and parametric variations compared with the conventional method.
This paper presents the modeling and simulation of wind energy Conversion System using the Permanent Magnet Synchronous Generator (PMSG). The objectives are: to extract the maximum power of the wind speed by controlling the electromagnetic torque of the PMSG, to maintain constant the DC-link voltage despite the wind speed variations and to attain the unity power factor. In order to ensure a regulation with high performance and a good robustness against the internal and the external disturbances, a new control strategy called the Active Disturbance Rejection Control (ADRC) is used. Therefore, the Analysis and simulation of the ADRC and PI controllers are developed with MATLAB/Simulink software. The performance of these controllers is compared in term of references tracking, robustness and grid faults.
In recent years, wind energy has become one of the most promising renewable energy sources. Various wind turbine concepts with different generator topologies have been developed to convert this abundant energy into electric power. The doubly-fed induction generator (DFIG) is currently the most common type of generator used in wind farms. Usually the DFIG generator is a wound rotor induction machine, where the stator circuit is directly connected to grid while the rotor’s winding is connected to the grid via a three-phase converter. This paper describes an approach for the independent control of the active and reactive powers of the variable-speed DFIG. The simulation model including a 1.5 MW-DFIG driven by a wind turbine, a PWM back-to-back inverter and the proposed control strategy are developed and implemented using MATLAB/Simulink/SimPowerSystems environment.
Effcacious pitch angle control of variable-speed wind turbine using fuzzy bas...Kashif Mehmood
The Wind energy is more reliable and speedier growing, among the renewable energy resources, due to the world
environment challenges as well as increasing demand for energy. The wind turbine system’s stability is cumbersome due to the
uneven distribution of wind. Centrifugal and gravitational loads on the blades of a wind turbine creates weariness, resultantly
decreases the power output along with the life of the equipment. Therefore, the need for a pitch angle control that can reduce
the loading effect in addition to provide maximal power output. This paper proposes the fuzzy based model-predictive controller
of pitch angle control to minimize the loading effect on wind turbine by limiting power output and rotor speed to its rated
value as well as to maximize the extracted power output as compared to other techniques. The fuzzy logic controller works
very effciently by encountering the system’s non-linearity while model predictive controller helps the system to become more
stable and effcient. The superiority of prescribed controller is verifed by comparing it with PI controller. The proposed model
has been tested in MATLAB/Simulink using a 3MW wind turbine system.
Wind Turbine Generator Tied To Grid Using Inverter Techniques and Its DesignsIJSRD
This paper proposes a method of using small sizes WTG of 300W low capacity turbine in small grid channel with inverter techniques. Power can be fed directly to grid by improving durability and eliminating battery usage, using WTG inverter technique. The proposed wind tied with grid by PMG includes boost converter and three phase inverter. For tracking wind speed with variations of wind power MPPT method is used. Interleaving technique is adopted for different frequency variables to improve power capacity. Final result proves WTG helps in improving wind power application as shown in simulation result.
Sliding mode performance control applied to a DFIG system for a wind energy p...IJECEIAES
This project presents a strategy of field control then sliding mode control put in to the conversion process of wind energy containing an asynchronous generator with double fed (DFAG; DFIG). A model was developed for each component of the wind turbine (turbine, DFAG and cascade rectifierinverter). MPPT device must be introduced in order to obtain maximum energy efficiency so that PI-MPPT method is made. The objective is to apply this command to control independently the active and reactive powers generated by the asynchronous generator uncoupled by orientation from the flow. The results of digital simulations obtained show the improvement of the performances of the sliding control compared to the field control, also it has provided information on the commands available techniques as reference tracking and robustness.
Analysis of PMSG in Wind Integration using T Source Inverter with Simple Boos...IJTET Journal
The Analysis of PMSG in wind integration using a T-source Inverter with the Simple Boost Control technique for
improving voltage gain is proposed. The Permanent Magnet Synchronous Generator (PMSG) offers higher performance than other
generators because of its higher efficiency with less maintenance. Since they don’t have rotor current, can be used without a gearbox,
which also implies a reduction of the weight of the nacelle with a reduction of costs. T-Source Inverter has high frequency, low
leakage inductance transformer and one capacitance this is the main difference from the Z-source Inverter. It has low active
components in compare with conventional ZSI. The T source network has an ability to perform DC to AC power conversion. It
provides buck boost operation in a single stage, but the traditional Inverter cannot provide such feature. All the components of the
wind turbine and the grid-side converter are developed and implemented in MATLAB/Simulink.
Tracking of Maximum Power from Wind Using Fuzzy Logic Controller Based On PMSGIJMER
Wind energy has gained a growing worldwide interest due to the nonstop rise in fuel cost.
The main aim of the wind-energy system is to extract the maximum power present in the wind stream. In
order to extract the highest power, the maximum power point tracking (MPPT) algorithm is used. This
paper proposes the fuzzy logic MPPT controller to track the maximum power from the wind generation
system. The maximum power is achieved based on the rotor speed of the wind system which consists of
wind turbine and PMSG. The error and change in error is given as input to the fuzzy logic and its output
is connected to the boost converter. The voltage from the dc link is controlled by the Voltage Source
Inverter (VSI), and it is placed in grid side converter control. The proposed system is designed and
evaluated in MATLAB/SIMULINK. Simulation results show the good dynamic performance of the
proposed system
A Fuzzy Logic Control Strategy for Doubly Fed Induction Generator for Improve...IAES-IJPEDS
In this paper, which is t

decouple PI control for output active and reactive powers
he common control technique for power converter of Doubly Fed
Induction Generator (DFIG) is presented. But there are some disadvantages with this control method like uncertainty about the exact model, behavior of some parameters or unpredictable wind speed and tuning of PI parameters. To overcome the mentioned disadvantages a fuzzy logic control of DFIG wind turbine is presented and is compared with PI controller. To validate the proposed scheme, simulation results are presented, these results showed that the performance of fuzzy control of DFIG is excellent and it improves power quality and stability of wind turbine compared to PI controller. The Fuzzy logic controller is applied to rotor side converter for active power control and voltage regulation of wind turbine. The entire work is carried out in MATLab/Simulink. Different faulty operating conditions are considered to
prove the effective implementation of the proposed control scheme.
1. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
DOI : 10.14810/ijscmc.2014.3403 33
DYNAMIC RESPONSES IMPROVEMENT OF
GRID CONNECTED WPGS USING FLC IN HIGH
WIND SPEEDS
Maziar izadbakhsh1*
, Majid Gandomkar1
, Alireza Rezvani1
and Saeed Vafaei1
1
Department of Electrical Engineering, Saveh Branch, Islamic Azad University, Saveh,
Iran
ABSTRACT
Environmental and sustainability concerns are developing the significance of distributed generation (DG)
based on renewable energy sources. In this paper, dynamic responses investigation of grid connected wind
turbine using permanent magnet synchronous generator (PMSG) under variable wind speeds and load
circumstances is carried out. In order to control of turbine output power using Fuzzy Logic controller
(FLC) in comparison with PI controller is proposed. Furthermore, the pitch angle based on FLC using
wind speed and active power as inputs, can have faster responses, thereby leading to smoother power
curves, enhancement of dynamic performance of wind turbine and prevention of mechanical damages to
PMSG. Inverter adjusted the DC link voltage and active power is fed by d-axis and reactive power is fed by
q-axis (using P-Q control mode). Simulation of wind power generation system (WPGS) is carried out in
Matlab/Simulink, and the results verify the correctness and feasibility of control strategy.
Keywords
Dynamic responses, FLC, Pitch Angle, PMSG, P-Q control
1. INTRODUCTION
Renewable energy systems are of significance as being modular, nature-friendly and domestic.
Virtually, all regions of the world have renewable resources. By this point of view studies on
renewable energies concentrate more attention. Solar energy and wind energy are the two
renewable energy sources most common in use. Among those renewable energy sources, wind
energy stands as a true alternative to conventional technologies for electricity generation. Wind
energy also has the clean energy aspect which is especially important, considering the effects of
global warming [1, 2]. Fixed speed and variable speed wind turbine generator systems are
emerging in the wind power industry, although the former is rarely considered for new
installations. One of the major drawbacks of fixed speed wind turbine generator system is that it
cannot capture maximum power from the wind. A few types of variable speed wind turbine
generator systems are commercially available today. A PMSG is recognized as a promising
technology to use as a wind generator in both the direct-drive system and the system using a
simple single-stage gearbox. One of the major advantages is the high power density of this type of
machine [2, 3].
Another advantage of variable wind turbines is the capability of maximum power point tracking
(MPPT) from wind energy sources [4]. Variable speed wind turbines operate in two primary
2. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
34
regions, below rated power and above rated power. When power production is below the rated
power for the machine, the turbine operates at variable rotor speeds to capture the maximum
amount of energy available in the wind [5, 6]. In above-rated power conditions, the primary
objective is to maintain a constant power output. This is generally achieved by holding the
generator torque constant and varying the blade pitch angle. MPPT controller somehow changes
the rotor speed according to variation of wind speed that the tip speed ratio (TSR) is maintained
in optimum value.
One of the methods to reach the maximum power point (MPP) is pitch angle control (B). In high
speeds wind the extra production of active power via wind turbine lead to increases consuming of
reactive power in generator and in which case, it should utilizes the reactive power compensator
for injecting reactive power that has extra cost too [7]. In the past, PIDs is used mostly in
controllers design but, by introduction of fuzzy logic instead of PID, created a better performance
and best preventative way to eliminate the profound mathematical understanding of system. In
comparing PIDs and Fuzzy logic systems, fuzzy logic has more stability, faster and smoother
response, smaller overshoot and does not need a fast processor, Also it's more powerful than other
non-linear controllers [8, 9]. Some authors have already presented on variable wind turbine using
PMSG technology, including dynamic and transient characteristics [10, 11]. Various control
strategies can be adopted for the operation of the generator and grid side converter, as proposed in
[11, 12].
In these papers [13-15], pitch angle based on FLC is presented. In [15] active power and in [13,
14] both reactive power and rotational rotor speed are used as input signals and because in
mentioned items wind speed's been ignored, the controller has not fast response and may cause
mechanical damages to synchronous generator. Also, another problem in these articles that it is
not practically connected to grid [14-18], but the grid connected mode in this paper is proposed to
analyse the system performance. In recent years, many topologies based on power electronic
devices with different level of complexity and cost is developed investigated in order to connect a
PMSG to network. There are two modes for inverter operating: 1) Active and reactive control
mode (P-Q control), 2) Voltage and frequency control mode (V-F control) [19, 20].
Analysis performance of grid connected PMSG wind turbine in P-Q control mode under load
circumstances and variable wind speeds and also, enhancement of dynamic performance in
WPGS using pitch angle based on FLC is investigated. P-Q control strategy is derived from Park
transformation and it’s simulated in Matlab software. The pitch angle is designed based on FLC
by adding wind speed as an input signal to adjust the turbine output power in extra high speed.
2. STURUCTURE OF GRID CONNECTED WPGS
The diagram of a WPGS based on PMSG integrated to grid is illustrated in Figure 1. Turbine
output is rectified by using uncontrolled rectifier. Then DC link voltage is adjusted by PI
controller until it reaches a constant value and then, the constant voltage is inverted to AC voltage
using sinusoidal PWM inverter. Inverter adjusted the DC link voltage and injected active power
by d-axis and injected reactive power by q-axis using PQ control method. Furthermore, turbine
output is regulated through pitch angle based on FLC in extra high wind speeds. By increasing
pitch angle via fuzzy controller, the exceeding power of wind turbine is limited, reaching to the
nominal value and reducing inverter output current. Therefore, by the reduction of injected output
power of wind turbine, the injection of extra total active power to grid is decreased.
3. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
35
Figure 1. The block diagram of WPGS
2.1. Variable Wind Turbine Modelling
The amount of electricity that a turbine is able to produce depends on the speed of rotor and the
speed of the wind that propels the rotor [21, 22]. Aerodynamic wind power is calculated in
equation (1).
3
p w(P 0 AC ).5 , V= λ βρ (1)
W
λ = m
w
R
V
(2)
Where P, ρ, A , Vw, Wm and R are power, air density, rotor swept area of the wind turbine ,
wind speed in m/sec, rotor speed in rad/sec and radius of turbine respectively. Also, Cp is the
aerodynamic efficiency of rotor.
21
p
116
C , 0.5176 0.) 4 5(
−
λ β = − −
iλ
i
β e
λ
(3)
1
i 3
1 0.035
0.08 1
−
λ = − + + λ β β
(4)
Furthermore, the Cp depends on TSR and blade pitch angle. Figure 2 shows the typical variation
of Cp respect to the TSR or various values of the pitch angle (β) [23].
4. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
36
Figure 2. Cp Vs λ for various pitch angles (β)
2.2. PMSG Modelling
A synchronous generator with reference to Park’s transformation is illustrated which d-axis is
rotating along magnetic field direction. PMSG voltage equations are given by [24, 25]:
ds
ds s ds q qs
d
di 1
V R i ωL i
dt L
= − − + (5)
qs
qs s qs d ds m
q
di 1
V R i ωL i ω
dt L
= − − − + φ (6)
Where Vds and Vqs are d and q axis machine voltages and Ids and Iqs are d and q axis machine
currents, Rs: Stator Resistance, W: electrical angular frequency, Ld: d axis inductance, Lq: q axis
inductance, mφ : amplitude of the flux linkage caused by permanent magnet. If rotor is
cylindrical (Ld ≈ Lq = Ls), the electromagnetic torque equation written as following:
e
3
T
2
= φ m q sp i (7)
Where, p is the number of pole pairs of the PMSG [26, 27].
2.3. Pitch Angle Based on FLC
FLC is made of three parts which is demonstrated in Figure 3. First part is fuzzification which is
the process of changing a real scalar value into a fuzzy set. Second part is fuzzy inference motor
that combines IF-THEN statements based on fuzzy principle and third part is defuzzification
5. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
37
which is the process that changes a fuzzy set into a real value in output [28, 29].
Figure 3. The Structure of FLC System
Proposed FLC is consisting of two input signal and one output signal. The first input signal is
based on deviation between active power from the rated value in P.U and it’s mentioned as error
signal. Thus, positive value indicate turbine’s normal operation and negative value shows the
extra power generation during above rated wind speed. In this case, controller should modify in
pitch angle degree which is done by increase the nominal value. The pitch angle degree is
regulated on zero in a normal condition, the whole wind energy can be converted to mechanical
energy and when the pitch angle start to increase from zero value, the wind attach angle to blades
is increase that lead to aerodynamic power reduction and consequently the output power is draw
down. Besides, the second signal taken from anemometer which is located on top of nacelle.
Controller’s response is so faster when wind speed is used as an input signal comparing to the
time that inputs are rotor rotational speed, reactive power and active power in large turbines with
high moment of inertia [13-15]. However, mechanical erosion in large and high speed turbines is
diminished by adjusting the FLC. Designing of pitch angle based on FLC for wind turbine power
adjustment in high wind speeds, is being proposed. By increasing pitch angle via fuzzy controller,
the exceeding power of wind turbine is limited, reaching to the nominal value. Three Trapezoidal
membership functions are considered in this paper. Also Min-Max method is used as a
defuzzification reference mechanism for centroid. Given membership functions are shown in
Figure 4.
(a)
6. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
38
(b)
(c)
Figure 4. The membership function of fuzzy logic: (a) Membership functions of active power
(error signal), (b) Membership functions of wind speed, (c) Membership functions of output (β)
Also, the rules are implemented to obtain require pitch angle are shown in Table 1. Where the
linguistic variables are represented by VG(very great), SG (small great), OP (optimum), SL
(small low) and VL (very low) for error signal and VL (very low),SL (small low), OP (optimum),
SH (small high) and VH (very high) for wind speed signal and for output signal NL (negative
large), NS (negative small), Z (zero),PS (positive small) and PL (positive large), respectively.
Figure 5 Shows the three dimensional curve of inputs and output.
Table 1. Fuzzy rules
Pitch command Active power (Error)
Wind
speed
VG SG OP SL VL
VL PL PS Z Z Z
SL PL PS Z Z Z
OP PL PS Z Z Z
SH PL PS PS PS PS
VH PL PL PL PL PL
7. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
39
Figure 5. The three dimensional curve in fuzzy logic
3. INVERTER CONTROL STRATEGY (P-Q)
A three phase DC-AC voltage source inverter (VSI) is used for grid connection via pulse width
modulation (PWM) technic. By applying inverter via PWM technic produces high frequency
harmonics which lead to filter and eliminate the harmonics. The VSI can play role as an ideal
sinusoidal voltage source.
Since wind power is fluctuates due to wind velocity, output voltage and frequency change
continuously. A bridge rectifier provides AC to DC and then DC link voltage using PI controller
to obtain constant value, then DC voltage will be inverted to get desired AC voltage [20].
3
P ( )
2
= +gd d gq qV I V I (8)
3
Q ( )
2
= −gq d gd qV I V I (9)
If synchronous frame is synchronized with grid voltage, voltage vector is V=Vgd+j0 which active
and reactive power may be as following:
3
P
2
= gd dV I (10)
3
Q
2
= gd qV I (11)
Synchronous reference is calculate quantities of d-axis, q-axis and zero sequence in two axis
rotational reference vector for three phase sinusoidal signal illustrated in Figure 6. The equations
are given by (12), (13).
8. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
40
Figure 6. The synchronous reference machine
d a d a
q b q b
0 c 0 c
V V i i
V C V , i C i
V V i i
= =
(12)
dq0
2π 2πcosθ cos(θ ) cos(θ )
3 3
2 2π 2πC sinθ sin(θ ) sin(θ )
3 33
1 1 1
2 2 2
− +
− − − − +
=
(13)
Inverter control model is illustrated in Figure 7. The target of grid side controller is to keep the
DC link voltage in constant value, regardless of power amplitude. Inverter control strategy is
consisting of two control loops. Internal control loop is control the grid current and external
control loop is control the voltage. Internal control loop which is responsible for power quality
such as low total harmonic distortion (THD) and improvement of power quality and external
control loop is responsible for balancing the power.
One of the most important characteristics of P-Q control loop is the capability of independent
performance of grid. Another benefit of this mode is increasing operational reliability and power
quality. The external loop capacitor voltage control is used to set reference current for d-axis in
order to control active power .The q-axis reference current is allocated to inverter output reactive
power [25]. If power factor is unit, therefore this current will be zero. The phase locked loop
(PLL) blocks which measure the voltage phase angle θg is based on Park transformation and also
synchronize the inverter to grid [30].
9. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
41
Figure 7. The inverter control model
4. SIMULATION RESULTS
In this section, simulation results under different terms of operation using Matlab/Simulink are
presented. System block diagram is shown in Figure 8.
PMSG parameters: Stator resistance per phase: 2.5 , Inertia: 0.82e-3
kg-m2
, Torque constant:
12N-M/A, Pole pairs: 8, Output power: 90kW, Nominal speed: 12 m/s, Ld =La= 7.2 mH. Grid
parameters: X/R: 7, F: 60 Hz, Vgrid: 220V and other parameters, DC link capacitor: 5100µF, DC
link voltage: 1100V, Type of load: inductive, Load power: 90kW.
Figure 8. The block diagram of grid connected WPGS in Matlab/Simulink
10. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
42
4.1. Case Study
In this case, the evaluation of FLC with comparing to conventional PI controller in pitch angle of
WPGS is carried out. The dynamic performance of WPGS under variations of wind speed and
load circumstances is investigated. There is no power exchange between WPGS and grid in
normal condition.
During 0 < t < 1 s, the load power is 90kW and at t= 1 s, it has %25 step increase in load that is
constant until t=2 s. Then, at t=3 s, it has step decrease 40% in load power, that is constant until
t=4 s. Wind speed during 0< t <5 s is 12 m/s and at t= 5 s, it is reduced to 10 m/s. Then, during 5<
t < 7, wind speed is 10 m/s and after that, at t=7 s, it is extremely increased to 19m/s. By
designing FLC, when wind speed is more than nominal speed (12 m/s), turbine output power is
increased by extremely increasing wind speed; however, with PI controller, the power is constant
at a high level and in the presence of FLC, it is reduced to the nominal power and made smoother,
thereby leading to the prevention of mechanical fatigue to generator.
Figure 9 shows the variation of wind speed in proposed system. Inverter output voltage is
invariant, which is shown in Figure 10. The variation of pitch angle in the presence of FLC is
depicted in Figure 11. As can be seen, in normal situations, the pitch angle is set as zero. At wind
speeds above the rated wind, the extracted wind power has to be limited by increasing the pitch
angle (β). Figures 12 and 13 show the inverter output current with the PI controller and in the
presence of FLC, respectively. It shows the effectiveness of fuzzy controller by increasing pitch
angle. The exceeding power of wind turbine is limited and also, the inverter output current is
reduced by FLC in comparison to PI controller. Figures 14 and 15 show the turbine output power
with PI controller and in the presence of FLC according to variation of wind speed. By increasing
the pitch angle via FLC, the exceeding power of wind turbine is limited, reaching to the nominal
value. DC link voltage remains at a constant value (1100V), thereby proving the effectiveness of
the established P-Q controller as illustrated in Figure 16. The reactive power produced by the
WPGS is regulated at zero that, the power factor maintained unity as shown in Figure 17. The
grid current with PI controller and FLC are shown in Figures 18 and 19, respectively.
One of the most important aspects of using DG sources and connecting them to grid is keeping
the THD at the minimum of its value. According to IEEE Std.1547.2003, it should be around 5%.
In THD curve, it is around 5% to 7%, which is shown Figure 20. Grid voltage is depicted in
Figure 21. It can be observed from Figure 15, that pitch angle based on FLC can limit the
exceeding output power of wind turbine. Therefore, by the reduction of output power of wind
turbine, the injection of extra total active power to grid is declined. The exchange active powers
among grid and WPGS are illustrated in Figures 22 and 23.
Figure 9. Variation of wind speed
11. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
43
Figure 10. Inverter output voltage
Figure 11. Variation of pitch angle by FLC
Figure 12. Inverter output current by PI controller
12. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
44
Figure 13. Inverter output current by FLC
Figure 14. Turbine output power by PI controller
Figure 15. Turbine output power by FLC
13. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
45
Figure 16. DC link voltage
Figure 17. Reactive power
Figure 18. Grid current by PI controller
14. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
46
Figure 19. Grid current by FLC
Figure 20. THD (%)
Figure 21. Grid voltage
15. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
47
Figure 22. Active powers by PI controller
Figure 23. Active powers by FLC
5. CONCLUSIONS
In the proposed paper, the dynamic responses of grid connected wind turbine using PMSG under
load circumstances and variation of wind speed was carried out. Control strategy and precise
modelling of DC/AC grid connected converter was presented. Inverter adjusted the DC link
voltage and active power was fed by d-axis and reactive power was fed by q-axis (using P-Q
control mode).
The simulation results indicated that using FLC could dramatically reduce the disadvantages of PI
method. Moreover, the presented FLC in the WPGS, by adding wind speed as an input signal,
could have faster and smoother, prevent more mechanical fatigue and also, the dynamic
performance of wind turbine could be improved. On the other hand, by increasing pitch angle via
FLC, the exceeding power of wind turbine was limited, reaching to the nominal value and
reduced inverter output current. Therefore, by the reduction of injected output power of wind
turbine, the injection of extra total active power to grid was declined. It was clear that, the WPGS
by applying FLC in pitch angle and also, with the cooperation of grid could easily meet the load
demand.
16. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
48
REFERENCES
[1] M.Izadbakhsh, M.Gandomkar, A.Rezvani and A.Ahmadi,‘’Short-term resource scheduling of a
renewable energy based micro grid’’, Renewable Energy,Vol.75, pp.598-606, 2015.
[2] A.Rezvani, M.Gandomkar, M.Izadbakhsh and A.Ahmadi,‘’Environmental/economic scheduling of a
micro-grid with renewable energy resources’’, Journal of Cleaner Production,Vol.87, pp. 216-226,
2015.
[3] P. Vas, Electrical Machines and Drives: A Space Vector Theory Approach. New York, USA: Oxford
Univ. Press, 1992.
[4] J. F. Manwell, J. G. Mcgowan, A. L. Rogers, Wind Energy Explained: Theory, Design and
Application, John Wiley & Sons Ltd, Chichester, 2002.
[5] M.G. Simoes, B.K. Bose, and R.J. Spiegel, “Fuzzy Logic Based Intelligent Control Of A Variable
Speed Cage Machine Wind Generation System,” IEEE Transactions On Power Electronics, vol. 12,
no 1, pp.87-95, 1997.
[6] E.B.Muhandoa, T. Senjyua, H. Kinjob and T. Funabashi, “Augmented LQG controller for
enhancement of online dynamic performance for WTG system”, Renewable Energy, vol.33, pp.1942–
1952, 2008.
[7] K.Y. Lo, Y. M. Chen, and Y. R. Chang,’’ MPPT Battery Charger for Stand-Alone Wind Power
System’’, IEEE transactions on power electronics, vol. 26, no. 6, pp. 1631 – 1638, 2011.
[8] J.Y.M. Cheung, A.S. Kamal,” Fuzzy Logic Control of refrigerant flow”, UKACC International
Conference on Control, Conference Publication,Vol.96, No. 427 ,pp. 2-5 ,September 1996.
[9] Gaurav, A. Kaur," Comparison between Conventional PID and Fuzzy Logic Controller for Liquid
Flow Control: Performance Evaluation of Fuzzy Logic and PID Controller by Using
MATLAB/Simulink", International Journal of Innovative Technology and Exploring Engineering
(IJITEE), Vol.1, no.1, pp. 84-88, June 2012.
[10] M. Chinchilla, S. Arnaltes, and J. C. Busgos, “Control of permanent magnet synchronous generators
applied to variable-speed wind-energy systems connected to the grid,” IEEE Trans. Energy Convers.,
vol. 21, no. 1, pp. 130–135, Mar. 2006.
[11] S. Morimoto, T. Nakamura, and Y. Takeda, “ Power maximization control of variable-speed wind
generation system using permanent magnet synchronous generator,” IEEJ Trans. Power Energy, vol.
123, no. 12, pp. 1573–1579, 2003.
[12] N. A. Cutululis, E. Ceanga, A. D. Hansen, and P. Sørensen, “Robust multi-model control of an
autonomous wind power system,” Wind Energy, vol. 9, no. 5, pp. 399–419, 2006.
[13] X. Lingfeng, Y. Xiyun, L. Xinran, and X. Daping, "Based on adaptive fuzzy sliding mode controller,"
in Intelligent Control and Automation, WCICA 7th World Congress on china, pp. 2970-2975, 2008.
[14] C. A. M. Amendola and D. P. Gonzaga, "Fuzzy-Logic Control System of a Variable-Speed Variable-
Pitch Wind-Turbine and a Double-Fed Induction Generator", in Intelligent Systems Design and
Applications, Seventh International Conference on Brazil, pp. 252-257, 2007.
[15] T. Senjyu, R. Sakamoto, N. Urasaki, T. Funabashi, and H. Sekine, "Output power leveling of wind
farm using pitch angle control with fuzzy neural network," in Power Engineering Society General
Meeting, IEEE, Japan, pp.1- 8,2006.
[16] X. Yao, Ch. Guo and Z. Xing, Y. Li, S. Liu’’ Variable Speed Wind Turbine Maximum Power
Extraction Based on Fuzzy Logic Control’’, International Conference on Intelligent Human-Machine
Systems and Cybernetics ,China, pp.202 – 205,2009.
[17] Q. Zeng , L. Chang , R. Shao ,’’ Fuzzy-logic-based maximum power point tracking strategy for
PMSG variable-speed wind turbine generation systems ’’ , Electrical and Computer Engineering,
CCE Canadian Conference on, pp. 405-410,2008.
[18] T.L.Van , D.CH.Lee ,’’ Output power smoothening of variable - speed wind turbine systems by
pitch angle control’’ , IPEC 2012 Conference on Power & Energy, pp.166-171, 2012.
[19] A. Kahrobaeian , Y.A.-R.I. Mohamed , “Analysis and Mitigation of Low-Frequency Instabilities in
Autonomous Medium-Voltage Converter-Based Microgrids With Dynamic Loads ”, IEEE Trans. on
Industrial Electronics ,vol. 61, no.4, pp. 1643 - 1658, 2014.
[20] C.T. Lee , R.P. Jiang , P.T. Cheng , “A Grid Synchronization Method for Droop-Controlled
Distributed Energy Resource Converters”, IEEE Trans. on Industry Application, Vol.49, no.2, pp. 954
- 962, 2013.
17. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 4, November 2014
49
[21] Md. Arifujjaman, “Modeling, Simulation and Control of Grid Connected Permanent Magnet
Generator (PMG)-based Small Wind Energy Conversion System” IEEE Electrical Power & Energy
Conference, Canada, pp.1-6, 2010.
[22] Z. Lubosny,‘’ Wind Turbine Operation in Electric Power Systems’’, Berlin, Springer, 2003.
[23] A. Uehara , A.Pratap , T. Goya , T. Senjyu, A. Yona , N. Urasaki and T. Funabashi, “A Coordinated
Control Method to Smooth Wind Power Fluctuations of a PMSG-Based WECS” IEEE Transactions
on Energy Conversion, Vol. 26, No. 2, pp. 550-558, June 2011.
[24] M. Rosyadi , S. M. Muyeen , R. Takahashi , J. Tamura’’ Fuzzy-PI Controller Design for PM Wind
Generator to Improve Fault Ride Through of Wind Farm’’, International journal of renewable energy
research Marwan Rosyadi et al., Vol.3, No.2,pp.308-314, 2013.
[25] C. Krause, ‘’Analysis of electric machinery’’, 2nd Edition, United States of America: Willey, 2002.
[26] L. barote, C. marinescu ‘’Modeling and Operational Testing of an Isolated Variable Speed PMSG
Wind Turbine with Battery Energy Storage’’ Advances in Electrical and Computer Engineering, Vol.
12, No. 2, pp.81-88, 2012.
[27] Y. oner, N. bekiroglu, S. ozcira ‘’Dynamic Analysis of Permanent Magnet Synchronous Generator
with Power Electronics ’’,Advances in Electrical and Computer Engineering, Vol. 10, No. 2, pp.11-
15, 2010.
[28] M. Rosyadi, S.M. Muyeen, R. Takahashi, J. Tamura, “Transient stability enhancement of variable
speed permanent magnet wind generator using adaptive pi-fuzzy controller,” in Proc. Trondheim
Power Tech. Conf, Germany, pp.1-6,2011.
[29] L. X. Wang, ‘’ A course in fuzzy systems and control’’, New Jersey: Prentice Hall, 1997.
[30] A. Rolan , A. Luna, G. Vazquez, D. Aguilar and G. Azevedo , “Modeling of a Variable Speed Wind
Turbine with a Permanent Magnet Synchronous Generator”, IEEE International Symposium on
Industrial Electronics (ISlE 2009), Korea , July 5-8, pp. 734-739, 2009.
Authors
MaziarIzadbakhshwas born in Tehran, Iran in 1989. Hereceived his B.Sc and M.Sc degrees
in electrical power engineering from Islamic Azad University,Saveh Branch, Iran in 2011 and
2014, respectively. His research interests include the renewable energy, microgrid, Power
system planning and operation, hybrid systemand optimization
MajidGandomkar was born in the Saveh, Iran. He received PHD degree of Electrical
Engineering from Science and Research Branch of Islamic Azad University. His research
interests include distribution systems, DG systems ,optimization. Now, he is Assistant
Professor at Islamic Azad University, Saveh Branch.
AlirezaRezvaniwas born in Tehran, Iran in 1989. Hereceived his B.Sc and M.Sc degrees in
electrical power engineering from Islamic Azad University,Saveh Branch, Iran in 2011 and
2014, respectively. His research interests include the renewable energy, microgrid,Power
system planning and operation, hybrid systemand optimization.