Wind Turbine Emulator Research Articles

Design validation of a laboratory-scale wind turbine emulator

AbstractPresented in this study is an investigation of the real-time performance of a laboratory-scale model of wind turbine emulator. Developed to provide a cost-effective experimental facility for demonstrating and validating wind energy conversion systems at new wind territories, the emulator comprises a software component with a hardware interface of a motor-driven wound rotor induction generator. A real-life wind speed profile is implemented on the model to investigate its performance under a near-real-world scenario and, some operational characteristics of real wind energy conversion systems are exactly replicated by the emulator in the course of the experimentation. The emulator could therefore be considered suitable for use as a laboratory level testbed for the demonstration and validation of wind energy conversion systems in the real-time.

Autonomous PV-Array Excited Wind-Driven Induction Generator for Off-Grid Application in India

Isolated renewable energy systems that are based fully on renewable resources but are at the same time reliable are necessary for meeting the power demands of remote places where utility grid is not available and for which hybrid wind–solar systems play a crucial role. In this paper, a simplified control scheme has been presented for a standalone hybrid photovoltaic (PV) array-excited wind-driven induction generator (IG), considering a three-phase variable load with or without unbalance. The proposed scheme exploits the ruggedness and cost-effective IG as a viable alternative for an expensive permanent magnet synchronous generator, which is invariably used in standalone small wind turbines. Any standalone system employs a battery, however, the system is supposed to deliver power even in the absence of battery and the batteryless mode of operation is presented in this paper. The control scheme has been validated with simulation as well as hardware results. Extensive field tests have been performed using 2.4-kW PV panels, 2.2-kW wind turbine emulators, and weather stations for performance evaluation. The validation results have been presented, which show that the proposed scheme is expected to be an attractive solution for remote application where utility grid is either not feasible or not economical.

An efficiency experimented wind turbine emulator linked to transmission line model 380 kV

In this paper, the author investigates an experimental wind turbine emulator linked to a transmission line model 380 kV. Before presenting and analyzing the experimental results that deals with the voltages, the Ferranti effect, the active and the reactive powers at the sending end and the receiving end with different kinds of loads, the author presents firstly a theoretical study dealing with the model of the wind turbine, the salient synchronous generator and the transmission line. The Ferranti effect and the power analysis are also presented. Theoretical study and experimental results are benefits and advantageous.

Condition monitoring of a wind turbine generator using a standalone wind turbine emulator

The intend of this paper is to give a description of the realization of a low-cost wind turbine emulator (WTE) with open source technology from graze required for the condition monitoring to diagnose rotor and stator faults in a wind turbine generator (WTG). The WTE comprises of a 2.5 kW DC motor coupled with a 1 kW squirrel-cage induction machine. This paper provides a detailed overview of the hardware and software used along with the WTE control strategies such as MPPT and pitch control. The emulator reproduces dynamic characteristics both under step variations and arbitrary variation in the wind speed of a typical wind turbine (WT) of a wind energy conversion system (WECS). The usefulness of the setup has been benchmarked with previously verified WT test rigs made at the University of Manchester and Durham University in UK. Considering the fact that the rotor blades and electric subassemblies direct drive WTs are most susceptible to damage in practice, generator winding faults and rotor unbalance have been introduced and investigated using the terminal voltage and generated current. This wind turbine emulator (WTE) can be reconfigured or analyzed for condition monitoring without the need for real WTs.

Improved differential evolution‐based Elman neural network controller for squirrel‐cage induction generator system

An improved differential evolution (IDE) algorithm-based Elman neural network (ENN) controller is proposed to control a squirrel-cage induction generator (SCIG) system for grid-connected wind power applications. First, the control characteristics of a wind turbine emulator are introduced. Then, an AC/DC converter and a DC/AC inverter are developed to convert the electric power generated by a three-phase SCIG to the grid. Moreover, the dynamic model of the SCIG system is derived for the control of the square of DC-link voltage according to the principle of power balance. Furthermore, in order to improve the transient and steady-state responses of the square of DC-link voltage of the SCIG system, an IDE-based ENN controller is proposed for the control of the SCIG system. In addition, the network structure and the online learning algorithm of the ENN are described in detail. Additionally, according to the different wind speed variations, a lookup table built offline by the dynamic model of the SCIG system using the IDE is provided for the optimisation of the learning rates of ENN. Finally, to verify the control performance, some experimental results are provided to verify the feasibility and the effectiveness of the proposed SCIG system for grid-connected wind power applications.

Implementation of Sliding Mode Control System for Generator and Grid Sides Control of Wind Energy Conversion System

This paper presents a second order sliding mode control strategy to control the generator and the grid sides of a variable speed experimental wind energy conversion system. At the generator side, the rotational speed is controlled to track a profile generated from the power curve of the wind turbine for maximum power extraction. At the grid side, the dc-link voltage is regulated for a proper transfer of power. The control strategy is based on a disturbed single input-single output error model and a second order sliding mode control algorithm. The proposed second order sliding mode control strategy offers interesting characteristics such as robustness to parametric uncertainties in the turbine and the generator as well as external disturbances. The proposed strategy, for speed and dc-link voltage control in wind energy conversion system, is validated on an emulated wind turbine driven by the OPAL-RT real-time simulator (OP5600). Experimental results show that the proposed control strategy is effective in terms of speed and dc-link voltage control. The sliding mode control approach is robust against unknown disturbances, parametric variations, and uncertainties in the system. Furthermore, it produces no chattering in the generated torque, which reduces the mechanical stress on the wind turbine.

Study on dynamic characteristic of wind turbine emulator based on PMSM

In this paper, a wind turbine emulator (WTE) based on the load torque dynamic compensation of PMSM is proposed to satisfy the further study of wind power system control technology in laboratory. The basic characteristic of wind turbine is analyzed to compare the wind turbine with its WTE. The dynamic compensation method based on the acceleration feedback is improved to propose the load torque dynamic compensation method to realize the dynamic characteristic simulation of wind turbine. Moreover, a low pass filter (LPF) is adopted at the load torque compensation module to suppress the torque ripple of the wind generator. An entire wind power system experimental platform is built to test the proposed torque compensation method. The results verify the proposed control method.

An emulator for fixed pitch wind turbine studies

A wind turbine emulator is an important hardware to simulate wind energy conversion systems. The emulator hardware is often built by a coupled motor as prime mover and controlled by a variable speed drive to the shaft of an electrical generator. In this work, we propose, design and implement a novel wind turbine emulator by using a squirrel cage induction machine and permanent magnet induction generator. The control of the prime mover is performed by an IGBT AC drive. The drive itself is controlled by a 32-bit microprocessor. Furthermore, the computer supervises the drive and generates the wind patterns and sets the configuration of wind turbine models. This allows the user to define different wind patterns and to emulate different wind turbines. The combination of the PI controller, the computer supervision, and the microprocessor ensures an accurate performance of entire system. The frequency of the generated voltage is proportional to the shaft rotational speed. Therefore, the output voltage frequency is used as a rotational speed meter. RS-485 is the main communication channel between the drive and the computer. Finally, the results demonstrate the effective and accurate performance of the proposed emulator in reproducing the dynamics of an actual wind turbine.

Wind turbine emulator based on blade element momentum theory for variable‐speed wind power generation system

This paper proposes a wind turbine emulator (WTE) based on the blade momentum theory, and tests the variable‐speed wind power generation system using a pulse‐width modulation (PWM) converter to verify the accuracy of the emulator. The behavior of the wind turbine for natural wind is reproduced by the WTE based on the proposed theory. The variable‐speed wind power generation system employs a vector control system to control the torque and speed of the permanent magnet synchronous generator in the converter side. The windmill rotational speed is controlled to maximize the efficiency of the wind turbine against wind velocity. And the active power and reactive power are controlled in the inverter side, and the generated power is sent to the grid while controlling the DC link voltage to be constant at the same time. The behaviors of the WTE are compared with the simulation results and experimental results using a real wind turbine. These experimental and simulation results show that the test bench with the proposed WTE has sufficient performance and accuracy to verify variable‐speed wind generator systems. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Real-Time Control of Active and Reactive Power for Doubly Fed Induction Generator (DFIG)-Based Wind Energy Conversion System

This paper presents the modeling, rapid control prototyping, and hardware-in-the-loop testing for real-time simulation and control of a grid-connected doubly fed induction generator (DFIG) in a laboratory-size wind turbine emulator for wind energy conversation systems. The generator is modeled using the direct-quadrature rotating reference frame circuit along with the aligned stator flux, and the field-oriented control approach is applied for independent control of the active and reactive power and the DC-link voltage at the grid side. The control of the active, reactive power and the DC-link voltage are performed using a back-to-back converter at sub- and super-synchronous as well as at variable speeds. The control strategy is experimentally validated on an emulated wind turbine driven by the Opal-RT real-time simulator (OP5600) for simultaneous control of the DC-link voltage, active and reactive power.

Development details and performance assessment of a Wind Turbine Emulator

This paper describes an experimental platform to emulate the static and dynamic behavior of real Wind Energy Conversion Systems (WECS). The Wind Turbine Emulator (WTE) consists of two coupled 1.5 kW squirrel-cage induction machines. The WTE calculations are performed on a PC and a DSP, both connected via USB. The total torque applied to the WTE motor is the difference of the scaled wind mechanical torque calculated on the PC, and the turbine inertia torque calculated on the DSP. An improved WTE shaft speed derivative has been used for the inertia torque calculation, which provides better results in terms of attenuation of the high-frequency harmonics present in the generator speed acquisition. The implemented WTE is used to compare different MPPT algorithms and to test power overrating and low voltage ride through procedures.

Displacement of the maximum power point caused by losses in wind turbine systems

The energy yield of wind turbines is to a large extent determined by the performance of the Maximum Power Point Tracking (MPPT) algorithm. Conventionally, they are programmed to maximize the turbines power coefficient. However, due to losses in the generator and converter, the true optimal operating point of the system shifts. This effect is often overlooked, which results in a decreased energy yield. Therefore, in this paper, the wind turbine system is modeled including the dominant loss components to investigate this effect in detail. By simulations and experiments on a wind turbine emulator, it is shown that the location of the maximum power point is significantly affected for low wind speeds. For high wind speeds, the effect is less pronounced. The parameter of interest is the increase in yearly energy output with respect to the classical MPPT method, which is calculated in this paper by including a Rayleigh wind speed distribution. For typical average wind speeds, the energy yield can increase with 1–2%. There is no cost associated with operating the turbine in the overall MPP, making it worthwhile to include this effect. The findings are implemented in an MPPT algorithm to validate the increased performance in a dynamic situation.

Experimental Assessment with Wind Turbine Emulator of Variable-Speed Wind Power Generation System using Boost Chopper Circuit of Permanent Magnet Synchronous Generator

This paper presents experimental results and its assessment of a variable-speed wind power generation system (VSWPGS) using permanent magnet synchronous generator (PMSG) and boost chopper circuit (BCC). Experimental results are obtained by a test bench with a wind turbine emulator (WTE). WTE reproduces the behaviors of a windmill by using servo motor drives. The mechanical torque references to drive the servo motor are calculated from the windmill wing profile, wind velocity, and windmill rotational speed. VSWPGS using PMSG and BCC has three speed control modes for the level of wind velocity to control the rotational speed of the wind turbine. The control mode for low wind velocity regulates an armature current of generator with BCC. The control mode for middle wind velocity regulates a DC link voltage with a vector-controlled inverter. The control mode for high wind velocity regulates a pitch angle of the wind turbine with a pitch angle control system. The hybrid of three control modes extends the variable-speed range. BCC simplifies the maintenance of VSWPGS while improving reliability. In addition, VSWPGS using PMSG and BCC saves cost compared with VSWPGS using a PWM converter.

Modelling and Development of Wind Turbine Emulator for the Condition Monitoring of Wind Turbine

This paper presents the modeling and development of a wind turbine emulator using a 2.5 KW 1750 RPM DC motor coupled to a 1.5 KW 1500 RPM SEIG to assist the condition monitoring of Wind turbine. Mathematical modeling of wind turbine, separately excited DC-Machine and SEIG coupled with capacitor bank are realized in Matlab/Simulink environment. The effectiveness of the setup was found by comparing the error between various parameters calculated by the simulation model and actual WTE setup- under both static and dynamic conditions. Response of SEIG has also been analyzed under different load conditions. Operating performance of the generated current and voltage using the FFT has also been analysed.The proposed approach was implemented on Advantech-4704 real-time interface card and LABVIEW real-time control programming. The developed WTE can analyzed or reconfigured for condition monitoring of WECS without need of real wind turbines.

Banco de Emulación de Perfiles de Viento para Aplicaciones en Energía Eólica

El trabajo presenta el desarrollo de un banco de emulación de perfiles de viento, incluyendo el sistema de conversión de energía eólica a energía eléctrica. El banco completo de emulación consta de un elemento motriz, encargado de proporcionar perfiles pares/velocidad, correspondientes a datos reales de disponibilidad eólica de un lugar geográfico particular. El elemento motriz, constituido en este banco de emulación por un motor de corriente continua de 3.3 kW, se acopla al elemento generador, en este caso una máquina de rotor bobinado (DFIG por sus siglas en inglés), de 4.0 kW @ 50 Hz. Las máquinas eléctricas se alimentan a través de un sistema de potencia compuesto por un puente rectificador y un puente H, para la máquina de corriente continua, y un convertidor dual en configuración “back to back” para la máquina de inducción de rotor bobinado. Los elementos conmutadores del sistema de potencia son módulos duales de transistores bipolares de compuerta aislada (IGBT). Se utilizan dos bloques disipadores de calor, uno para el conjunto rectificador/puente-H, y otro para el convertidor dual. La velocidad del eje del conjunto de máquinas se mide utilizando un codificador óptico. Las señales necesarias para el control, del sistema emulador, se miden mediante dos tarjetas de sensores de tensión/corriente, con capacidad para medir 16 señales en total. Para el control de los convertidores se utiliza una tarjeta basada en un arreglo de lógica programable (FPGA) interconectada con un procesador digital de señales (DSP) que permite la alta velocidad de procesamiento requerida para probar distintas técnicas de control. El convertidor es controlado por modulación de ancho de pulso (PWM) conmutando a una frecuencia ajustable, en este caso se selecciona una portadora de 10kHz.

Adaptive Fuzzy Logic Control of Wind Turbine Emulator

In this paper, a Wind Turbine Emulator (WTE) based on a separately excited direct current (DC) motor is studied. The wind turbine was emulated by controlling the torque of the DC motor. The WTE is used as a prime mover for Permanent Magnet Synchronous Machine (PMSM). In order to extract maximum power from the wind, PI and Fuzzy controllers were tested. Simulation results are given to show performance of proposed fuzzy control system in maximum power points tracking in a wind energy conversion system under various wind conditions. The strategy control was implemented in simulation using MATLAB/Simulink. DOI: http://dx.doi.org/10.11591/ijpeds.v4i2.5809

Realization and control of a wind turbine connected to the grid by using PMSG

This paper studies the control of a variable-speed wind turbine using the permanent magnet synchronous generator (PMSG) driven by a wind turbine emulator. The wind turbine is realized by imposing the wind profile on emulator to behave as the real wind turbine when it receives the same wind profile. This wind turbine is connected to the grid by means of a two back-to-back voltage-fed pulse width-modulation (PWM) converters to interface the generator and the grid. This paper has three main objectives, the first is realization of the wind turbine emulator, the second is extracting and exploiting the maximum power from the wind, the third is feeding the grid by high-power and good electrical energy quality; to achieve that, we applied the strategies of maximum power point tracking (MPPT) using optimal torque control which allows the PMSG to operate at an optimal speed. The inverter is used for delivering power to the grid, controlled in a way to deliver only the active power into the grid, thus we have unit power factor. DC-link voltage is also controlled by the inverter. This paper shows the dynamic performances of the complete system by its simulation using Matlab Simulink. Experimental results has verified and validated the wind turbine emulator and the efficiency of MPPT control method using a variable wind profile.

Dynamic control for permanent magnet synchronous generator system using novel modified recurrent wavelet neural network

Because permanent magnet synchronous generator (PMSG) system driven by permanent magnet synchronous motor (PMSM) based on wind turbine emulator (WTE) is a nonlinear and time-varying system with high complication, an accurate dynamic model of the PMSG system directly driven by WTE is difficult to establish for the linear controller design. In order to conquer this difficulty and improve the robustness of dynamic system, the PMSG system controlled by the online-tuned parameters of the novel modified recurrent wavelet neural network (NN)-controlled system is proposed to control output voltages and powers of controllable rectifier and inverter in this study. First, a closed-loop PMSM-driven system based on WTE is designed for driving the PMSG system to generate output power. Second, the rotor speeds of the PMSG, the voltages, and currents of the two power converters are detected simultaneously to yield maximum power output. In addition, two sets of the online-tuned parameters of the modified recurrent wavelet NN controllers in the controllable rectifier and inverter are developed for the voltage-regulating controllers in order to improve output performance. Finally, some experimental results are verified to show the effectiveness of the proposed novel modified recurrent wavelet NN controller for the power output of the PMSG system driven by WTE.

An Induction Motor Based Wind Turbine Emulator

Abstract The authors present a small-scale wind turbine emulator based on the AC drive system and discuss the methods for power coefficient calculation. In the work, the experimental set-up consisting of an AC induction motor, a frequency converter, a synchronous permanent magnet generator, a DC-DC boost converter and DC load was simulated and tested using real-life equipment. The experimentally obtained wind turbine power and torque diagrams using the emulator are in a good agreement with the theoretical ones.

A Simulation System of Wind Turbine Based on Labwindows

Wind energy is the worlds fastest growing renewable energy source in recent years, and it has drawn worldwide attention. Due to high efficiency, simple topology and stable operation, variable speed constant frequency (VSCF) direct-drive wind power generation system using permanent magnet synchronous generator (PMSG) is the development trend and one of the focuses of wind power generation system research. The paper introduces the trend of the development wind power generation and the recently research stage on the wind power generation. Based on the VSCF power fundamental principle, the dissertation analyzes the strategy of wind turbine simulation. In the development of wind power generating system, the wind turbine emulator becomes more and more important because it can provide controllable wind turbine characteristics. Simplified mathematical model based on the CT-λ curve is constructed, the system structure and emulation method are analyzing. Hardware and software are designed and implemented, and a laboratory set-up is building which based on DC motor. Experimental results show that the wind turbine emulator is as good as expected.