FPGA-based reconfigurable control for switch fault tolerant operation of WECS with DFIG without redundancy

This paper deals with reconfigurable back-to-back converter topology and control orders in Wind Energy Conversion Systems (WECS). A typical WECS with Doubly Fed Induction Generator (DFIG) in balanced conditions is concerned. Based on the classical topology, a fault tolerant converter without any redundancy has been studied. The presented fault tolerant topology allows a “five-leg” structure with converters reconfiguration after switch failure detection. Furthermore, the control strategy for classical topology can no longer be applied after fault occurrence. Thus, a “five-leg” control strategy has also been proposed. The validation of the reconfigurable digital controller for the studied WECS with DFIG topology has been performed using a Hardware-in-the-Loop (HIL) reconfigurable platform including a Field Programmable Gate Array (FPGA) chip. HIL simulation results in both healthy and fault conditions have been presented to show simultaneously the viability of the studied converters topology and the reconfigurable control.     

Five-leg converter topology for wind energy conversion system with doubly fed induction generator

In this paper, application of a five-leg converter in Doubly Fed Induction Generator (DFIG) for Wind Energy Conversion Systems (WECS) is investigated. The five-leg structure and its PWM control are studied and performances are compared with the classical six-leg topology. The main drawback of five-leg converter with respect to the six-leg back-to-back converter is the need to increase the dc-link voltage for the same operation point, i.e. the same powers in case of WECS. So, different methods for the reduction of the required dc-link voltage in the five-leg case are studied. The five-leg converter is used to replace the conventional six-leg one, with the same ability. For the performance evaluation of this structure and its fully digital controller in a more realistic and experimental manner, Hardware in the Loop experiments is carried out. It is shown that efficient control of active and reactive powers and dc-link voltage is performed. Hardware in the Loop results demonstrate the high performance of the proposed fully digital control which is implemented on an Altera FPGA target.     

Blade pitch control malfunction simulation in a wind energy conversion system with MPC five-level converter

This paper is on a wind energy conversion system simulation of a transient analysis due to a blade pitch control malfunction. The aim of the transient analysis is the study of the behavior of a back-to-back multiple point clamped five-level full-power converter implemented in a wind energy conversion system equipped with a permanent magnet synchronous generator. An alternate current link connects the system to the grid. The drive train is modeled by a three-mass model in order to simulate the dynamic effect of the wind on the tower. The control strategy is based on fractional-order control. Unbalance voltages in the DC-link capacitors are lessen due to the control strategy, balancing the capacitor banks voltages by a selection of the output voltage vectors. Simulation studies are carried out to evaluate not only the system behavior, but also the quality of the energy injected into the electric grid.     

DFIG sliding mode control fed by back-to-back PWM converter with DC-link voltage control for variable speed wind turbine

This paper proposes an indirect power control of doubly fed induction generator (DFIG) with the rotor connected to the electric grid through a back-to-back pulse width modulation (PWM) converter for variable speed wind power generation. Appropriate state space model of the DFIG is deduced. An original control strategy based on a variable structure control theory, also called sliding mode control, is applied to achieve the control of the active and reactive power exchanged between the stator of the DFIG and the grid. A proportional-integral-(PI) controller is used to keep the DC-link voltage constant for a back-to-back PWM converter. Simulations are conducted for validation of the digital controller operation using Matlab/Simulink software.     

Wind Energy literature survey no.1

In order to help keep readers up‐to‐date in the field, Wind Energy contains a list of recently published articles drawn from issues of the following periodicals: IEEE Transactions on Energy Conversion, IEEE Transactions on Power Electronics, IEEE Transactions on Control Systems Technology, International Journal of Energy Research, Journal of Wind Engineering and Industrial Aerodynamics, American Institute of Aeronautics and Astronautics Journal and Transactions of the ASME: Journal of Dynamic Systems Measurement and Control. The list is arranged alphabetically by author. Compiled by Martin Hird, UMIST, PO Box 88, Manchester, M60 1QD, UK. Please e‐mail any suggestions to martin.hird@stud.umist.ac.uk martin.hird@stud.umist.ac.uk . Copyright © 2000 John Wiley & Sons, Ltd.     

Design and implementation of an energy efficient power conditioner for fuel cell generation system

The energy use of the world grows continuously and the development of a clean distributed power generation becomes environmentally important. Fuel cells are one such integral part of Renewable Energy Sources based clean energy supply; that they operate with hydrogen as fuel and water with heat as process waste. Due to the electrochemical reaction, fuel cell has the power quality of delivering low voltage with high current capability. Here an attempt is made to develop a power conditioner with a series of conversion to get a 220 V sinusoidal AC, 50 Hz single phase voltage of low distortion and fast dynamic regulation to cater load variations. A novel Polyphase Boost DC-to-DC switching converter based on parallel connection of 8 identical converters with current mode control is devised to have minimum reflected ripple current and voltage injected to fuel cell input. A full bridge converter with high frequency transformer isolation, step-up the DC voltage level from the low voltage fuel cell along with poly phase boost converter, deliver required DC to the PWM inverter, which generate AC utility power output. Recent trend of Ultra-capacitor based transient energy storage and retrieval system, to cater for the sluggish behavior of fuel cell, for load transients is incorporated. DSP and FPGA based digital real time controllers are used to realize the gating of MOSFETs and IGBTs used in the power conditioner. A 1 kW power conditioner is developed for a PAFC fuel cell system with 12 V DC nominal and their performance evaluations are satisfactory.     

Modeling of small wind turbines based on PMSG with diode bridge for sensorless maximum power tracking

The Permanent Magnet Synchronous Generator (PMSG) with diode bridge is frequently used in small Wind Energy Conversion Systems (WECS). This configuration is robust and cheap, and therefore suitable for small WECS. In order to achieve Maximum Power Point Tracking (MPPT) with no mechanical sensors, it is possible to impose the relationship between the DC voltage and the DC current on the optimum operating points. However, this relationship is difficult to calculate theoretically since the whole system is involved. In fact, as there is no model of the whole system in the literature, the optimum curve I_L¹(V_dc) is obtained with experimental tests or simulations. This paper develops an accurate model of the whole WECS, thereby making it possible to relate the electrical variables to the mechanical ones. With this model, it is possible to calculate the optimum curve I_L¹(V_dc) from commonly-known system parameters and to control the system from the DC side. Experimental results validate the theoretical analysis and show that maximum power is extracted for actual wind speed profiles.     

Low voltage ride through of doubly-fed induction generator connected to the grid using sliding mode control strategy

Wind Energy Conversion System (WECS) based on Doubly Fed Induction Generator (DFIG) connected to the grid is subjected to high transient currents at rotor side and rise in DC-link voltage during voltage sag at stator/grid side. To secure power system operation wind turbines have to meet grid requirements through the Low voltage ride through (LVRT) capability and contribute to grid voltage control during severe situations. This paper presents the modeling and control designs for WECS based on a real model of DFIG taking into account the effect of stator resistance. The non-linear control technique using sliding mode control (SMC) strategy is used to alter the dynamics of 1.5 MW wind turbine system connected to the grid under severe faults of grid voltage. The paper, also discusses the transient behavior and points out the performance limit for LVRT by using two protection circuits of an AC-crowbar and a DC-Chopper which follow a developed flowchart of system protection modes under fault which achieved LVRT requirements through results. The model has been implemented in MATLAB/SIMULINK for both rotor and grid side converters.     

Variable-speed generation with the series-resonant converter

Results of study and measurements are presented for a variable-speed generation (VSG) system that uses a series-resonant converter to excite the rotor windings of a doubly-fed generator. The capabilities of this system include maximum-efficiency operation and limited converter rating for a speed range from stand-still (zero RPM) to well beyond synchronous speed, as well as flexibility for line-voltage control, reactive power generation, and synchronization at zero RPM. Measurements of the harmonic distortion are provided showing the superiority of this converter as compared with a VSG system using a conventional cycloconverter or a DC-link converter. A convenient tool for analyzing the operating modes of the system is discussed that can be developed under varying resource conditions     

Wind energy literature survey No. 5

In order to help keep readers up‐to‐date in the field, Wind Energy contains a list of recently published articles drawn from recent issues of the following periodicals: IEEE Transactions on Energy Conversion, IEEE Transactions on Power Electronics, IEEE Transactions on Control Systems Technology, International Journal of Energy Research, Journal of Wind Engineering and Industrial Aerodynamics, American Institute of Aeronautics and Astronautics Journal, Transactions of the ASME: Journal of Dynamic Systems Measurement and Control and Renewable Energy. The list is arranged alphabetically by author. Compiled by Dave Rollinson, UMIST, PO Box 88, Manchester, M60 1QD, UK. Please e‐mail any suggestions to D.Rollinson@student.umist.ac.uk. Copyright © 2004 John Wiley & Sons, Ltd.     

Wind Energy Literature Survey No. 2

In order to help keep readers up‐to‐date in the field, Wind Energy contains a list of recently published articles drawn from issues of the following periodicals: IEEE Transactions on Energy Conversion, IEEE Transactions on Power Electronics, IEEE Transactions on Control Systems Technology, International Journal of Energy Research, Journal of Wind Engineering and Industrial Aerodynamics, American Institute of Aeronautics and Astronautics Journal, Transactions of the ASME: Journal of Dynamic Systems Measurement and Control, and Renewable Energy. The list is arranged alphabetically by author. Compiled by Martin Hird, UMIST, PO Box 88, Manchester M60 1QD, UK. Please e‐mail any suggestions to martin.hird@stud.umist.ac.uk. Copyright © 2001 John Wiley & Sons, Ltd.     

Effective active power control of a high penetration wind diesel system with a Ni–Cd battery energy storage

High penetration (HP) Wind Diesel Hybrid Systems (WDHS) have three modes of operation: Diesel Only (DO), Wind Diesel (WD) and Wind Only (WO). The HP-WDHS presented in this article consists of a Wind Turbine Generator (WTG), a Diesel Generator (DG), the consumer Load, a Ni–Cd Battery based Energy Storage System (BESS), a discrete Dump Load (DL) and a Distributed Control System (DCS). The DG includes a friction clutch which allows the Diesel Engine (DE) to be engaged (DO and WD modes)/disengaged (WO mode) to the Synchronous Machine (SM). The DCS consists of a sensor node which measures the SM speed and active power, calculates the reference active power P_REF necessary to balance the active power in the WDHS and communicates this P_REF value through a message to the BESS and DL actuator nodes. In the WD mode both the DG and WTG supply active power to the system and the DE speed governor regulates the system frequency. However in an HP-WDHS the power produced by the WTG (P_T) can be greater than the one consumed by the load (P_L). This situation means a negative power in the DG (power inversion) with its speed governor unable to regulate frequency. To avoid this situation, the DCS must order coordinated power consumption to the BESS and DL in order to keep the DG produced power positive. In this article it is shown by simulation how the DCS manages both a temporary power inversion and a permanent one with the mandatory transition from WD to WO mode. The presented graphs for frequency, voltage, active powers of the system elements and battery voltage/current show the effectiveness of the designed control.     

Wind Energy literature survey no. 3

In order to help keep readers up‐to‐date in the field, Wind Energy contains a list of recently published articles drawn from issues of the following periodicals: IEEE Transactions on Energy Conversion, IEEE Transactions on Power Electronics, IEEE Transactions on Control Systems Technology, International Journal of Energy Research, Journal of Wind Engineering and Industrial Aerodynamics, American Institute of Aeronautics and Astronautics Journal, Transactions of the ASME: Journal of Dynamic Systems Measurement and Control, and Renewable Energy. This survey additionally contains articles from a special wind energy issue of Transactions of the ASME: Journal of Solar Energy Engineering. The list is arranged alphabetically by author. Compiled by Martin Hird, UMIST, PO Box 88, Manchester, M60 1QD, UK. Please e‐mail any suggestions to martin.hird@stud.umist.ac.uk. Copyright © 2001 John Wiley & Sons, Ltd.     

High-efficiency grid-connected photovoltaic module integrated converter system with high-speed communication interfaces for small-scale distribution power generation

This paper presents a high-efficiency grid-connected photovoltaic (PV) module integrated converter (MIC) system with reduced PV current variation. The proposed PV MIC system consists of a high-efficiency step-up DC-DC converter and a single-phase full-bridge DC-AC inverter. An active-clamping flyback converter with a voltage-doubler rectifier is proposed for the step-up DC-DC converter. The proposed step-up DC-DC converter reduces the switching losses by eliminating the reverse-recovery current of the output rectifying diodes. To reduce the PV current variation introduced by the grid-connected inverter, a PV current variation reduction method is also suggested. The suggested PV current variation reduction method reduces the PV current variation without any additional components. Moreover, for centralized power control of distributed PV MIC systems, a PV power control scheme with both a central control level and a local control level is presented. The central PV power control level controls the whole power production by sending out reference power signals to each individual PV MIC system. The proposed step-up DC-DC converter achieves a high-efficiency of 97.5% at 260 W output power to generate the DC-link voltage of 350 V from the PV voltage of 36.1 V. The PV MIC system including the DC-DC converter and the DC-AC inverter achieves a high-efficiency of 95% with the PV current ripple less than 3% variation of the rated PV current.     

Wind Energy Literature Survey No. 4

In order to help keep readers up‐to‐date in the field, Wind Energy contains a list of recently published articles drawn from recent issues of the following periodicals: IEEE Transactions on Energy Conversion, IEEE Transactions on Power Electronics, IEEE Transactions on Control Systems Technology, International Journal of Energy Research, Journal of Wind Engineering and Industrial Aerodynamics, American Institute of Aeronautics and Astronautics Journal, Transactions of the ASME: Journal of Dynamic Systems Measurement and Control and Renewable Energy. This survey additionally contains articles relating to power system voltage restoration from selected journals. Compiled by Martin Hird, UMIST, PO Box 88, Manchester, M60 1QD, UK. Please e‐mail any suggestions to martin.hird@stud.umist.ac.uk . Copyright © 2003 John Wiley & Sons, Ltd.     

Scheduling and control co-design for Networked Wind Energy Conversion Systems

Fieldbus, industrial Ethernet that is simple, reliable, economical, and practical, is widely used in Wind Energy Conversion Systems (WECSs). These techniques belong to the field of networked control systems. Network embedding to Wind Energy Conversion Systems brings many new challenges. Implementing a control system over a communication network causes inevitable time delays that may degrade performance and can even cause instability. This work addresses challenges related to the reliable control of wind energy conversion systems, based on the theoretical framework of networked control systems. A type of WECS with network-induced delay and packet dropout is modeled and adjustable deadbands are explored as a solution to reduce network traffic in WECSs. A method to study the reliable control of WECSs is presented, which takes into account system response as well as the network environment. After detailed theoretical analysis, simulation results are provided, which further demonstrate the feasibility of the proposed scheme.     

Wind Energy Literature Survey No. 6

In order to help keep readers up‐to‐date in the field, Wind Energy contains a list of recently published articles drawn from recent issues of the following periodicals: Journal of Wind Engineering and Industrial Aerodynamics, IEEE Transactions on Energy Conversion, IEEE Transactions on Power Electronics, IEEE Transactions on Control Systems Technology, Transactions of the ASME : Journal of Dynamic Systems Measurement and Control, American Institute of Aeronautics and Astronautics Journal, International Journal of Energy Research and Renewable Energy. Compiled by Dave Rollinson, UMIST, PO Box 88, Manchester, M60 1QD, UK. Please e‐mail any suggestions to D.Rollinson@student.umist.ac.uk.     

Wind energy literature survey no. 32

As a service to readers, Wind Energy regularly conducts literature surveys and publishes lists of relevant articles drawn from recent issues of Wind Energy itself and a large number of periodicals including the following: Journal of Wind Engineering and Industrial Aerodynamics, International Journal of Energy Research, Renewable Energy, Energy Sources, Journal of Solar Energy Engineering, American Institute of Aeronautics and Astronautics Journal, Electric Power Components and Systems along with a number of periodicals published by the Institute of Electrical and Electronics Engineers, and so on. The list is limited exclusively to journals not specifically devoted to wind energy and its applications. To assist the reader, the list is separated into broad categories. Although many papers fit several categories, each paper is listed only once under the category thought most appropriate. Please note that the inclusion in the list is not an endorsement of a paper's quality. Compiled by Lars Christian Henriksen, Department of Wind Energy, Technical University of Denmark, PO Box 49, DK‐4000 Roskilde, Denmark. Please e‐mail any suggestions to larh@dtu.dk . Copyright © 2014 John Wiley & Sons, Ltd.     

Wind energy literature survey no. 31

As a service to readers, Wind Energy regularly conducts literature surveys and publishes lists of relevant articles drawn from recent issues of Wind Energy itself and a large number of periodicals including: Journal of Wind Engineering and Industrial Aerodynamics, International Journal of Energy Research, Renewable Energy, Energy Sources, Journal of Solar Energy Engineering, American Institute of Aeronautics and Astronautics Journal, Electric Power Components and Systems along with a number of periodicals published by the Institute of Electrical and Electronics Engineers, and so on. The list is limited exclusively to journals not specifically devoted to wind energy and its applications. To assist the reader, the list is separated into broad categories. Although many papers fit several categories, each paper is listed only once under the category thought most appropriate. Please note that the inclusion in the list is not an endorsement of a paper's quality. Compiled by Lars Christian Henriksen, Department of Wind Energy, Technical University of Denmark, PO Box 49, DK‐4000 Roskilde, Denmark. Please e‐mail any suggestions to larh@dtu.dk . Copyright © 2014 John Wiley & Sons, Ltd.     

Wind energy potential at Palkalainagar

This paper uses the Weibull's distribution function to describe the wind speed frequency distribution at Palkalainagar (geographical co-ordinates N : 9°54′, E : 78°54′), Madurai, India using the one year data available. Weibull's parameters are used to estimate the wind data parameters for the site. Of the wind data parameters the most important one is the annual specific output (T_A). This is used in determining the annual energy output of a Wind Energy Conversion System (WECS) and in conducting cost-benefit analysis of wind-electricity generation. The parameter is used in evaluating the efficiency of WECS in the same site. Results show the possibilities of harnessing wind energy towards electricity generation.