Low power wind energy conversion system based on variable speed permanent magnet synchronous generators

This paper presents a low power wind energy conversion system (WECS) based on a permanent magnet synchronous generator and a high power factor (PF) rectifier. To achieve a high PF at the generator side, a power processing scheme based on a diode rectifier and a boost DC-DC converter working in discontinuous conduction mode is proposed. The proposed generator control structure is based on three cascaded control loops that regulate the generator current, the turbine speed and the amount of power that is extracted from the wind, respectively, following the turbine aerodynamics and the actual wind speed. The analysis and design of both the current and the speed loops have been carried out taking into consideration the electrical and mechanical characteristics of the WECS, as well as the turbine aerodynamics. The power loop is not a linear one, but a maximum power point tracking algorithm, based on the Perturb and Observe technique, from which is obtained the reference signal for the speed loop. Finally, to avoid the need of mechanical sensors, a linear Kalman Filter has been chosen to estimate the generator speed. Simulation and experimental results on a 2-kW prototype are shown to validate the concept. © 2013 John Wiley & Sons, Ltd.Carranza Castillo, O.; Garcerá Sanfeliú, G.; Figueres Amorós, E.; González Morales, LG. (2014). Low power wind energy conversion system based on variable speed permanent magnet synchronous generators. Wind Energy. 17(6):811-827. doi:10.1002/we.1598S811827176Ackermann, T. (Ed.). (2005). Wind Power in Power Systems. doi:10.1002/0470012684Muyeen, S. M., Shishido, S., Ali, M. H., Takahashi, R., Murata, T., & Tamura, J. (2008). Application of energy capacitor system to wind power generation. Wind Energy, 11(4), 335-350. doi:10.1002/we.265Ladenburg, J. (2009). 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IEEE Transactions on Power Electronics, 15(2), 268-277. doi:10.1109/63.838099Athab, H. S., Lu, D. D.-C., & Ramar, K. (2012). A Single-Switch AC/DC Flyback Converter Using a CCM/DCM Quasi-Active Power Factor Correction Front-End. IEEE Transactions on Industrial Electronics, 59(3), 1517-1526. doi:10.1109/tie.2011.2158771Barbosa, P., Canales, F., Crebier, J.-C., & Lee, F. C. (2001). Interleaved three-phase boost rectifiers operated in the discontinuous conduction mode: analysis, design considerations and experimentation. IEEE Transactions on Power Electronics, 16(5), 724-734. doi:10.1109/63.949505Yao, K., Ruan, X., Mao, X., & Ye, Z. (2011). Variable-Duty-Cycle Control to Achieve High Input Power Factor for DCM Boost PFC Converter. IEEE Transactions on Industrial Electronics, 58(5), 1856-1865. doi:10.1109/tie.2010.2052538Andriollo, M., De Bortoli, M., Martinelli, G., Morini, A., & Tortella, A. (2009). Control strategy of a wind turbine drive by an integrated model. Wind Energy, 12(1), 33-49. doi:10.1002/we.281Hansen, A. D., & Michalke, G. (2008). Modelling and control of variable-speed multi-pole permanent magnet synchronous generator wind turbine. Wind Energy, 11(5), 537-554. doi:10.1002/we.278Salvatore, N., Caponio, A., Neri, F., Stasi, S., & Cascella, G. L. (2010). Optimization of Delayed-State Kalman-Filter-Based Algorithm via Differential Evolution for Sensorless Control of Induction Motors. IEEE Transactions on Industrial Electronics, 57(1), 385-394. doi:10.1109/tie.2009.2033489Kazmi, S. M. R., Goto, H., Guo, H.-J., & Ichinokura, O. (2011). A Novel Algorithm for Fast and Efficient Speed-Sensorless Maximum Power Point Tracking in Wind Energy Conversion Systems. IEEE Transactions on Industrial Electronics, 58(1), 29-36. doi:10.1109/tie.2010.2044732Pucci, M., & Cirrincione, M. (2011). Neural MPPT Control of Wind Generators With Induction Machines Without Speed Sensors. IEEE Transactions on Industrial Electronics, 58(1), 37-47. doi:10.1109/tie.2010.2043043Ming Y Li G Ming Z Chengyong Z Modeling of the wind turbine with a permanent magnet synchronous generator for integration IEEE Power Engineering Society General Meeting, 2007 2007 1 6Carranza O Figueres E Garcera G Gonzalez LG Gonzalez-Espin F Peak current mode control of a boost rectifier with low distortion of the input current for wind power systems based on permanent magnet synchronous generators 13th European Conference on Power Electronics and Applications, EPE ’09 2009 1 10Eltamaly, A. M. (2007). Harmonics reduction of three-phase boost rectifier by modulating duty ratio. Electric Power Systems Research, 77(10), 1425-1431. doi:10.1016/j.epsr.2006.10.012Vorperian, V. (1990). Simplified analysis of PWM converters using model of PWM switch. Continuous conduction mode. IEEE Transactions on Aerospace and Electronic Systems, 26(3), 490-496. doi:10.1109/7.106126Ridley, R. B. (1991). A new, continuous-time model for current-mode control (power convertors). IEEE Transactions on Power Electronics, 6(2), 271-280. doi:10.1109/63.76813Carranza O Figueres E Garcera G Trujillo CL Velasco D Comparison of speed estimators applied to wind generation systems with noisy measurement signals ISIE 2010 IEEE International Symposium on Industrial 2010 3317 3322Yaoqin J Zhongqing Y Binggang C A new maximum power point tracking control scheme for wind generation International Conference on Power System Technology, PowerCon 2002 IEEE-PES/CSEE 2002 144 148PSIM 7.0 User's Guide (2006), Powersim Inc. 2006Carranza, O., Garcerá, G., Figueres, E., & González, L. G. (2010). Peak current mode control of three-phase boost rectifiers in discontinuous conduction mode for small wind power generators. Applied Energy, 87(8), 2728-2736. doi:10.1016/j.apenergy.2010.02.01

Analytical Evaluation of Surface-Mounted PMSG Performances Connected to a Diode Rectifier

This paper analyzes some operational issues of threephase surface-mounted permanent magnet synchronous generators (PMSGs) connected to a diode rectifier. This simple configuration coupled to a single-switch dc–dc converter is used in smallscale wind energy conversion systems, as well as in energy harvesting systems, to reduce costs. The diode rectifier causes an intrinsic limit for the maximum convertible power, which is related to the load impedance matching, and additional joule losses due to the distorted currents. By using an analytical steady-state model of the rectifier and of the PMSG, this paper discusses how to achieve two particularly meaningful operating conditions characterized respectively by the maximum power transfer and the maximum power per ampere. The theory is validated by simulation and test results on a prototype

Operation of a Six-Phase Induction Machine Using Series-Connected Machine-Side Converters

This paper discusses the operation of a multiphase system, which is aimed at both variable-speed drive and generating (e.g., wind energy) applications, using back-to-back converter structure with dual three-phase machine-side converters. In the studied topology, an asymmetrical six-phase induction machine is controlled using two three-phase two-level voltage source converters connected in series to form a cascaded dc link. The suggested configuration is analyzed, and a method for dc-link midpoint voltage balancing is developed. Voltage balancing is based on the use of additional degrees of freedom that exist in multiphase machines and represents entirely new utilization of these degrees. The validity of the topology and its control is verified by simulation and experimental results on a laboratory-scale prototype, thus proving that it is possible to achieve satisfactory dc-link voltage control under various operating scenarios. © 1982-2012 IEEE

Power Converter of Electric Machines, Renewable Energy Systems, and Transportation

Power converters and electric machines represent essential components in all fields of electrical engineering. In fact, we are heading towards a future where energy will be more and more electrical: electrical vehicles, electrical motors, renewables, storage systems are now widespread. The ongoing energy transition poses new challenges for interfacing and integrating different power systems. The constraints of space, weight, reliability, performance, and autonomy for the electric system have increased the attention of scientific research in order to find more and more appropriate technological solutions. In this context, power converters and electric machines assume a key role in enabling higher performance of electrical power conversion. Consequently, the design and control of power converters and electric machines shall be developed accordingly to the requirements of the specific application, thus leading to more specialized solutions, with the aim of enhancing the reliability, fault tolerance, and flexibility of the next generation power systems

Fault-tolerant efficient control of six-phase induction generators in wind energy conversion systems with series-parallel machine-side converters

This work discusses the implementation of an efficient fault-tolerant control m a multiphase wind energy conversion system. The conversion system consists of an asymmetrical six-phase induction generator supplied by four voltage source converters (VSCs) m a hybrid series/parallel configuration. Post-fault operation must preserve the current ratings of the system and should also maximize the generated power by means of a proper flux adjustment. Both requirements are achieved m this work using a non-linear optimization analysis and some modifications m the control scheme. Simulation results confirm the optimal and safe performance of the wind energy system under study

Enhancement of Transient Stability of DFIG Based Variable Speed Wind Generator Using Diode-bridge-type Non-superconducting Fault Current Limiter and Resistive Solid State Fault Current Limiter

The application of doubly-fed induction generator (DFIG) is very effective in the fast-growing wind generator (WG) market. The foremost concern for the DFIG based WG system is to maintain the transient stability during fault, as the stator of the DFIG is directly connected to the grid. Therefore, transient stability enhancement of the DFIG is very important. In this work, a diode-bridge-type nonsuperconducting fault current limiter (NSFCL) and resistive solid-state fault current limiter (R-type SSFCL) are examined to augment the transient stability of the DFIG based WG system.In simulations, temporary balanced and unbalanced faults were applied in the test system to investigate the proposed NSFCL and the R-type SSFCL transient stability performance. Besides a DC resistive superconducting fault current limiter (SFCL), bridge-type fault current limiter (BFCL) and series dynamic braking resistor (SDBR) are also considered to compare their performance with the proposed NSFCL and R-type SSFCL. These simulations were performed with Matlab/Simulink software. Simulation results clearly indicate that the NSFCL and R-type SSFCL enhances the transient stability of the DFIG based WG. Moreover, the NSFCL works better than the DC resistive SFCL, BFCL and SDBR in every aspect and R-type SSFCL works better than the SDBR in all aspect

DC/DC converter for offshore DC collection network

Large wind farms, especially large offshore wind farms, present a challenge for the electrical networks that will provide interconnection of turbines and onward transmission to the onshore power network. High wind farm capacity combined with a move to larger wind turbines will result in a large geographical footprint requiring a substantial sub-sea power network to provide internal interconnection. While advanced HVDC transmission has addressed the issue of long-distance transmission, internal wind farm power networks have seen relatively little innovation. Recent studies have highlighted the potential benefits of DC collection networks. First with appropriate selection of DC voltage, reduced losses can be expected. In addition, the size and weight of the electrical plant may also be reduced through the use of medium- or high-frequency transformers to step up the generator output voltage for connection to a medium-voltage network suitable for wide-area interconnection. However, achieving DC/DC conversion at the required voltage and power levels presents a significant challenge for wind-turbine power electronics.This thesis first proposes a modular DC/DC converter with input-parallel output-series connection, consisting of full-bridge DC/DC modules. A new master-slave control scheme is developed to ensure power sharing under all operating conditions, including during failure of a master module by allowing the status of master module to be reallocated to another healthy module. Secondly, a novel modular DC/DC converter with input-series-input-parallel output-series connection is presented. In addition, a robust control scheme is developed to ensure power sharing between practical modules even where modules have mismatched parameters or when there is a faulted module. Further, the control strategy is able to isolate faulted modules to ensure fault ride-through during internal module faults, whilst maintaining good transient performance. The ISIPOS connection is then applied to a converter with bidirectional power flow capability, realised using dual-active bridge modules.The small- and large-signal analyses of the proposed converters are performed in order to deduce the control structure for the converter input and output stages. Simulation and experimental results demonstrate and validate the proposed converters and associated control schemes.Large wind farms, especially large offshore wind farms, present a challenge for the electrical networks that will provide interconnection of turbines and onward transmission to the onshore power network. High wind farm capacity combined with a move to larger wind turbines will result in a large geographical footprint requiring a substantial sub-sea power network to provide internal interconnection. While advanced HVDC transmission has addressed the issue of long-distance transmission, internal wind farm power networks have seen relatively little innovation. Recent studies have highlighted the potential benefits of DC collection networks. First with appropriate selection of DC voltage, reduced losses can be expected. In addition, the size and weight of the electrical plant may also be reduced through the use of medium- or high-frequency transformers to step up the generator output voltage for connection to a medium-voltage network suitable for wide-area interconnection. However, achieving DC/DC conversion at the required voltage and power levels presents a significant challenge for wind-turbine power electronics.This thesis first proposes a modular DC/DC converter with input-parallel output-series connection, consisting of full-bridge DC/DC modules. A new master-slave control scheme is developed to ensure power sharing under all operating conditions, including during failure of a master module by allowing the status of master module to be reallocated to another healthy module. Secondly, a novel modular DC/DC converter with input-series-input-parallel output-series connection is presented. In addition, a robust control scheme is developed to ensure power sharing between practical modules even where modules have mismatched parameters or when there is a faulted module. Further, the control strategy is able to isolate faulted modules to ensure fault ride-through during internal module faults, whilst maintaining good transient performance. The ISIPOS connection is then applied to a converter with bidirectional power flow capability, realised using dual-active bridge modules.The small- and large-signal analyses of the proposed converters are performed in order to deduce the control structure for the converter input and output stages. Simulation and experimental results demonstrate and validate the proposed converters and associated control schemes