Control of a Stand Alone Variable Speed Wind Turbine with a Permanent Magnet Synchronous Generator

 ABSTRACT:

A novel control strategy for the operation of a permanent magnet synchronous generator (PMSG) based stand alone variable speed wind turbine is presented in this paper,. The direct drive PMSG is connected to the load through a switch mode rectifier and a vector controlled pulse width modulated (PWM) IGBT-inverter. The generator side switch mode rectifier is controlled to achieve maximum power from the wind. The load side PWM inverter is using a relatively complex vector control scheme to control the amplitude and frequency of the inverter output voltage. As there is no grid in a stand-alone system, the output voltage has to be controlled in terms of amplitude and frequency. The stand alone control is featured with output voltage and frequency controller capable of handling variable load. A damp resistor controller is used to dissipate excess power during fault or over-generation. The potential excess of power will be dissipated in the damp resistor with the chopper control and the dc link voltage will be maintained. Extensive simulations have been performed using Matlab/Simpower. Simulation results show that the controllers can extract maximum power and regulate the voltage and frequency under varying load condition. The controller performs very well during dynamic and steady state condition.

 

KEYWORDS:

 

1.      Permanent magnet synchronous generator

2.      Maximum power extraction

3.      Switch-mode rectifier

4.      Stand alone variable speed wind turbine

5.      Voltage and frequency control

 

SOFTWARE: MATLAB/SIMULINK

 

CONCLUSION:

Control strategy for a stand alone variable speed wind turbine with a PMSG is presented in this paper. A simple control strategy for the generator side converter to extract maximum power is discussed and implemented using Simpower dynamic system simulation software. The controller is capable to maximize output of the variable speed wind turbine under fluctuating wind. The load side PWM inverter is controlled using vector control scheme to maintain the amplitude and frequency of the inverter out put voltage. It is seen that the controller can maintain the load voltage and frequency quite well at constant load and under varying load condition. The generating system with the proposed control strategy is suitable for a small scale standalone variable speed wind turbine installation for remote area power supply. The simulation results demonstrate that the controller works very well and shows very good dynamic and steady state performance

 

 

REFERENCES:

[1] Müller, S., Deicke, M., and De Doncker, Rik W.: ‘Doubly fed induction genertaor system for wind turbines’, IEEE Industry Applications Magazine, May/June, 2002, pp. 26-33.

[2] H. Polinder, F. F. A. van der Pijl, G. J. de Vilder, P. J. Tavner, "Comparison of direct-drive and geared generator concepts for wind turbines," IEEE Trans. On energy conversion, vol . 21, no. 3, pp. 725-733, Sept. 2006.

[3] T. F. Chan, L. L. Lai, "Permanenet-magnet machines for distributed generation: a review," in proc. 2007 IEEE power engineering annual meeting, pp. 1-6.

[4] M. De Broe, S. Drouilhet, and V. Gevorgian, “A peak power tracker for small wind turbines in battery charging applications,” IEEE Trans. Energy Convers., vol. 14, no. 4, pp. 1630–1635, Dec. 1999.

[5] R. Datta and V. T. Ranganathan, “A method of tracking the peak power points for a variable speed wind energy conversion system,” IEEE Trans. Energy Convers., vol. 18, no 1, pp. 163–168, Mar. 1999.

Control of Permanent-Magnet Generators Applied to Variable-Speed Wind-Energy Systems Connected to the Grid

 ABSTRACT:

Wind energy is a prominent area of application of variable-speed generators operating on the constant grid frequency. This paper describes the operation and control of one of these variable-speed wind generators: the direct driven permanent magnet synchronous generator (PMSG). This generator is connected to the power network by means of a fully controlled frequency converter, which consists of a pulse width-modulation (PWM) rectifier, an intermediate dc circuit, and a PWM inverter. The generator is controlled to obtain maximum power from the incident wind with maximum efficiency under different load conditions. Vector control of the grid-side inverter allows power factor regulation of the windmill. This paper shows the dynamic performance of the complete system. Different experimental tests in a 3-kW prototype have been carried out to verify the benefits of the proposed system.

KEYWORDS: 

1.      Permanent-magnet generators

2.      Pulse width modulated (PWM) power converters

3.      Wind energy

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This work shows the performance of a direct-driven permanent-magnet synchronous generator used in variable speed wind-energy systems. When exciting the system with a real wind profile, the system is able to track maximum power using generated power as input. The speed controller sets the generator torque command, which is achieved through a current control loop. An efficient generator control has been proposed. To achieve this objective, the optimum generator d-axis current component is imposed by the power converter, i.e., the current that leads to the minimum losses. The proposed system has been implemented in a real-time application, with a commercial permanent-magnet synchronous generator and a dc drive that emulates the wind turbine behaviour. The real-time process is running in a dSPACE board that includes a TMS320C31 floating-point DSP. Experimental results show the appropriate behavior of the system.

REFERENCES:

[1] A. Grauers, “Efficiency of three wind energy generator systems” IEEE Trans. Energy Convers, vol. 11, no. 3, pp. 650–657, Sep. 1996.

[2] E. Spooner and A. C. Williamson, “Direct coupled, permanent magnet generators for wind turbine applications,” Proc. Inst. Elect. Eng.—Elect. Power Appl., vol. 143, no. 1, pp. 1–8, 1996.

[3] R. Pe˜na, J. C. Clare, and G. M. Asher, “Doubly fed induction generator using back-to-back PWM converters and its application to variable-speed wind-energy generation,” Proc. Inst. Elect. Eng.—Elect. Power Appl., vol. 143, no. 3, pp. 231–241, May 1996.

[4] Z. Chen and E. Spooner, “Simulation of a direct drive variable speed energy converter,” in Proc. Int. Conf. Electrical Machines, Istanbul, Turkey, 1998, pp. 2045–2050.

[5] A. Grauers “Design of direct driven permanent magnet generators for wind turbines,” M.S. thesis, Chalmers Univ. Technol., G¨oteborg, Sweden, 1996.

Operation, Control, and Applications of the Modular Multilevel Converter: A Review

ABSTRACT:

 The modular multilevel converter (MMC) has been a subject of increasing importance for medium/high power energy conversion systems. Over the past few years, significant research has been done to address the technical challenges associated with the operation and control of the MMC. In this paper, a general overview of the basics of operation of the MMC along with its control challenges are discussed, and a review of state of-the-art control strategies and trends is presented. Finally, the applications of the MMC and their challenges are highlighted.

KEYWORDS:

1.      Capacitor Voltage Balancing

2.      Circulating Current Control

3.      High-Voltage Direct Current (HVDC) Transmission

4.      Modular Multilevel Converter (MMC)

5.      Modulation Techniques

6.      Redundancy

7.      Variable-Speed Drive Systems

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

The salient features of the MMC, i.e., its modularity and scalability enable it to conceptually meet any voltage level requirements with superior harmonic performance, reduced rating values of the converter components and improved efficiency. Over the past few years, the MMC has become a subject of interest for various medium to high voltage/power system and industrial applications including HVDC transmission systems, FACTS, medium-voltage variable-speed drives, and medium/high voltage dc-dc converters.

For power system applications, e.g., HVDC systems and FACTS, the MMC has reached a certain level of maturity and seems to stand as the most promising technology as a number of MMC-HVDC systems and STATCOMs has been successfully implemented and installed. For medium-voltage variable-speed drives, there is still a plenty of room for further development and to address the operational and control issues of the MMC, specifically under constant-torque low-speed operation. One major problem that needs to be addressed is to minimize the magnitude of the capacitor voltage ripple of the converter SMs at low frequencies without sacrificing the converter efficiency, thereby making a reasonable tradeoff between the converter size/volume/cost and efficiency.

The introduction of a family of modular multilevel dc-dc converters, originated from the MMC topology, has opened up a new avenue on research and development of medium/high voltage dc-dc converters. To take the full advantage of these converters for various applications, advanced modulation strategies that enable high voltage conversion ratio, high efficiency and reduced component stresses are required. With a significant amount of MMC-derived converter topologies and applications, it is concluded that development of novel modulation and control strategies will be a major driving factor to shape the future of MMC applications.

REFERENCES:

[1] G. Ding, G. Tang, Z. He, and M. Ding, “New technologies of voltage source converter (VSC) for HVDC transmission system based on VSC,” in Proc. IEEE Power and Energy Society General Meeting, 2008, pp. 1–8.

[2] S. Allebrod, R. Hamerski, and R. Marquardt, “New Transformerless, Scalable Modular Multilevel Converters for HVDC-Transmission,” in Proc. IEEE Power Electronics Specialists Conf. (PESC), 2008, pp. 174– 179.

[3] J. Dorn, H. Huang, and D. Retzmann, “A New Multilevel Voltage- Sourced Converter Topology for HVDC Applications,” in Proc. Cigre Session, B4-304, Paris, 2008.

[4] R. Marquardt, “Modular multilevel converter: An universal concept for HVDC-networks and extended DC-bus-applications,” in Proc. International Power Electronics Conf., Jun. 2010, pp. 502–507.

[5] J. Dorn, H. Huang, and D. Retzmann, “Novel Voltage-Sourced Converters for HVDC and FACTS Applications,” in Proc. Conf. Cigre Symposium Osaka, Japan, 2007.

Novel Level Shifted PWM Technique for Unequal and Equal Power Sharing in Quasi Z Source Cascaded Multilevel Inverter for PV Systems

 ABSTRACT:

 Conventional Phase Shifted Pulse Width Modulation (PS-PWM) is a usual switching technique for Z source/Quasi Z Source (qZS) based Cascaded Multilevel Inverters (CMI) (qZS-CMI). PS-PWM scheme causes higher switching losses and creates electromagnetic interference (EMI) problem for higher number of cascaded modules. To address these issues, novel modified Level Shifted PWM (LS-PWM) technique is proposed with the aim of obtaining equal power from cascaded modules under abnormal condition. The direct use of the Alternate Phase Opposed Disposed PWM (APOD-PWM) results in an unequal power sharing between the qZSI modules, under all operating conditions. An effective carrier rotation is incorporated in the conventional APOD-PWM to make the equal power sharing between the qZSI modules. The proposed scheme is an excellent solution for the Photovoltaic (PV) systems to address the problem of partial or complete shading, temperature variation, PV module failure, and dust accumulation on the PV panels. Furthermore, the relation between the PSPWM and APOD-PWM is geometrically obtained, which indicates that the proposed modulation scheme gives higher voltage gain over LS-PWM and PS-PWM techniques. Additionally, detailed switching loss analysis for the proposed PWM methods are added to validate low switching losses and thus high efficiency. The MATLAB Simulink simulations are presented to verify the proposed modulation. Experimental prototype is developed, and the experimental outcomes validate the improved performance of the multilevel qZSI with proposed modulation.

 

KEYWORDS:

 

1.      Cascaded Multilevel Converter

2.      Impedance Source inverter (Z/qZSI)

3.      Phase Shifted Pulse Width Modulation

4.      Level Shifted Pulse Width Modulation

5.      Equal power distribution

6.       Photovoltaic (PV)

 

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

A novel APOD-PWM technique (equal and unequal power sharing) for the qZS-CMI has been reported in this article. This paper presents the relation between shoot through duty and modulation indices of PS-PWM and APOD-PWM. The proposed modulation technique (for qZS-CMI) combines the advantages of APOD-PWM (subsidiary of LS-PWM) and PS-PWM, resulting in high quality output voltages and harmonic free input currents drawn from the PV panels. The equal and unequal power sharing together, overcomes the drawbacks of conventional techniques. These APOD-PWM for qZS-CMI can be applied to the PV systems to address the real time problems of partial shading, dust accumulation, temperature variation and power distribution among the operating modules. To verify the advantages with proposed PWM techniques, detailed switching loss analysis, simulation and experimental results are presented. With carrier rotation in proposed PWM, equal utilization is observed whereas without carrier rotation, highest efficiency is observed. The proposed APOD-PWM techniques have nearly same THD as conventional schemes and higher voltage gain and power yielding capability with higher efficiency than PS-PWM thereby validating its feasibility for qZSI related applications.

REFERENCES:

[1] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, “Power electronics for renewable energy systems,” in Transportation and Industrial Applications, Hoboken, NJ, USA: Wiley, Jul. 2014.

[2] H. Abu-Rub, J. Holtz, J. Rodriguez and G. Baoming, "Medium-Voltage Multilevel Converters—State of the Art, Challenges, and Requirements in Industrial Applications," in IEEE Trans.Ind. Electron., vol. 57, no. 8, pp. 2581-2596, Aug. 2010.

[3] J. Rodr´ıguez, J. S. Lai, and F. Z. Peng, “Multilevel inverters: A survey of topologies, controls and applications,” IEEE Trans. Ind. Electron., vol. 49, no. 4, pp. 724–738, 2002.

[4] C. D. Fuentes, C. A. Rojas, H. Renaudineau, S. Kouro, M. A. Perez and T. Meynard, "Experimental Validation of a Single DC Bus Cascaded H-Bridge Multilevel Inverter for Multistring Photovoltaic Systems," in IEEE Trans.Ind. Electron., vol. 64, no. 2, pp. 930-934, Feb. 2017.

[5] J. Rodriguez, P. Hammond, J. Pontt, R. Musalem, P. Lezana, and M. Escobar, “Operation of a medium-voltage drive under faulty conditions,” IEEE Trans. Ind. Electron., vol. 52, no. 4, pp. 1080–1085, August 2005.

 

L-C Filter Design Implementation and Comparative Study with Various PWM Techniques for DCMLI

 ABSTRACT:

 

In recent time’s multi-level inverters are widely used I industrial application, grid integration, renewable system, buildings and smart grid technology, etc. Uninterruptible power supply has become indispensable to our society. Concern with power quality and grid integration, a pure sinusoidal voltage current waveform is necessary. For such reason a design of various filters is now emerged in research area. Filters have property to smooth current and voltage waveform. This paper proposes filter design guideline for L-C filter with IGBT based multi-level inverter. An L-C circuit used at the inverter output for filtering purposes and ensuring that the THD is lower. The L-C filter cancels all harmonics and a real pure sinusoidal output voltage and current is obtained. Variable voltage and frequency supply to A.C. drives is invariably obtained from a three-phase voltage source inverter. A various pulse width modulation (PWM) schemes are used. The most widely used PWM schemes for three phase voltage source inverters are carrier-based sinusoidal PWM (SPWM) and space vector PWM (SVPWM).

In this paper a method for an asynchronous motor with inverter and L-C output filter is presented and it is verified by simulations in Matlab-Simulink. The simulation results are presented for three-phase five-level diode clamped inverter followed by three-phase L-C filter. The simulation results are compared with sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) for diode clamped multilevel inverter (DCMLI) in terms of THD.

KEYWORDS:

 

1.      DCMLI

2.      SPWM

3.      SVPWM

4.      L-C filter

5.       PWM

6.      THD

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

In this paper, the multicarrier SPWM and SVPWM control schemes with phase disposition (PD) is presented for DCMLI. With and without L-C filter the design algorithm of filter is presented here with THD comparison for PWM techniques. With the use of filter, the output voltage is almost sinusoidal in nature. Analysis for THD contents with use of filter on the output side of inverter shows significant improvement in the THD contents compared to the results of without using filter. This shows usefulness of L-C filter for industrial, grid integration and renewable energy applications.

REFERENCES:

[1] Hyosung Kim and Seung-ki sul “Anovel filter design for output LC filters of PWM inverters”,Journal of Power Electronics, vol. 11, no. 1, January 2011.

Thomas G. Habetler, Rajendra naik and Thomas A Nondahl “Implementation of an Inverter Output LC Filter Used for DV/DT Reduction” IEEE Transactions on Power Electronics, vol.17, no. 3, May 2002.

[3] H. W. Van Der Broeck H.C Skundenly and G.V Stanke “Analysis and realization of a pulse width modulator based on voltage space vectors” IEEE Trans. Ind. Appl., vol. 24, no. 1, pp. 142􀂱150, Jan./ Feb. 1988.

[4] Anish Gopinath, Aneesh Mohamed A. S., and M. R. Baiju “Fractal based Space Vector PWM for Multilevel Inverter- A novel approach”,IEEE Transactions on Industrial Electronics, vol. 56, no. 4, April 2009.

[5] Maryam saeedifard,Reza Iravani Josep pou “Analysis and control of  DC-Capacitor-Voltage-Drift Phenomenon of a Passive Front-End Five-level converter”, IEEE Transactions on Industrial Electronics, vol. 54, no. 6, December 2007.

Evolution of Topologies, Modeling, Control Schemes, and Applications of Modular Multilevel Converters

ABSTRACT:

 

Modular multilevel converter (MMC) is one of the most promising topologies for medium to high-voltage, high power applications. The main features of MMC are modularity, voltage and power scalability, fault tolerant and transformer-less operation, and high-quality output waveforms. Over the past few years, several research studies are conducted to address the technical challenges associated with the operation and control of the MMC. This paper presents the development of MMC circuit topologies and their mathematical models over the years. Also, the evolution and technical challenges of the classical and model predictive control methods are discussed. Finally, the MMC applications and their future trends are presented.

 

KEYWORDS:

 

1.      Capacitor voltage ripple

2.      Circulating currents

3.      High-power converters

4.      High-voltage direct current (HVDC) transmission

5.      Medium-voltage motor drive

6.      Model predictive control

7.      Modular multilevel converters

8.       Multilevel converters

9.       Power quality

10.  Pulse width modulation

11.  Submodule capacitor voltage control

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

The attractive features of the modular multilevel converter (MMC) played a key role in the development of new HVDC transmission systems, medium-voltage motor drives, and power quality improvement technologies. These technologies are commercialized by various leading industrial manufacturers such as GE, Alstom, ABB, Siemens, and C-EPRI. Depending on the application, the MMC has several technical issues such as circulating currents, capacitor voltage ripple, and DC-bus faults. Also, a complex control system is required to meet the several control objectives of an MMC. The past few years, numerous studies are conducted to understand the behavior of the MMC, and resulting in new topologies, mathematical models, and control schemes. This paper presents a review of the recent developments in the MMC in terms of the submodule configurations, mathematical models, pulse width modulation schemes, classical control schemes, and high-performance model predictive control methods. Also, the state-of-the-art and emerging technologies in modular multilevel converters are discussed. Finally, the list of commercial applications based on the MMC, and their technical details are provided.

REFERENCES:

[1] J. Rodriguez, L. G. Franquelo, S. Kouro, J. I. Leon, R. C. Portillo, M. . M. Prats, and M. A. Perez, “Multilevel converters: An enabling technology for high-power applications,” Proc. IEEE, vol. 97, no. 11, pp. 1786–1817, Nov 2009.

[2] S. Kouro, J. Rodriguez, B. Wu, S. Bernet, and M. Perez, “Powering the future of industry: High-power adjust/able speed drive topologies,” IEEE Ind. Appl. Mag., vol. 18, no. 4, pp. 26–39, Jul 2012.

[3] H. Abu-Rub, J. Holtz, J. Rodriguez, and G. Baoming, “Medium-voltage multilevel converters: State of the art, challenges, and requirements in industrial applications,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2581–2596, Aug 2010.

[4] P. W. Wheeler, J. Rodriguez, J. C. Clare, L. Empringham, and A. Weinstein, “Matrix converters: a technology review,” IEEE Trans. Ind. Electron., vol. 49, no. 2, pp. 276–288, Apr 2002.

[5] L. Empringham, J. W. Kolar, J. Rodriguez, P. W. Wheeler, and J. C. Clare, “Technological issues and industrial application of matrix converters: A review,” IEEE Trans. Ind. Electron., vol. 60, no. 10, pp. 4260–4271, Oct 2013.

Control of a new stand-alone wind turbine-based variable speed permanent magnet synchronous generator using quasi-Z-source inverter

 ABSTRACT:

In this paper a new variable speed permanent magnet synchronous generator (PMSG)-based stand-alone wind energy conversion system (SWECS) is proposed. The interface between the PMSG and the isolated load is accomplished by a quasi-Z-source inverter (qZSI) with battery storage system. The battery-assisted qZSI can balance the stochastic fluctuations of the wind power injected to the load and improve the voltage and frequency control. In addition to the battery storage, a dump load is used in the proposed SWECS to better maintain the active power balance and stability of the dc-link voltage during over-generation condition as well as sudden load changes. The proposed control system is able to provide an uninterrupted and reliable supply to sensitive loads under various power generation scenarios of the SWECS and sudden changes in the load demand. Moreover, the proposed controller provides maximum power point tracking (MPPT) which is essential for optimum operation of the SWECS. The validity of the proposed system is proved by simulation results carried out using MATLAB/ SIMULINK.

KEYWORDS:

1.      Permanent magnet synchronous generator (PMSG)

2.      Stand-alone wind energy conversion system (SWECS)

3.      Quasi-Z-source inverter (qZSI)

4.      Battery storage system

5.      Dump load

6.      Maximum power point tracking (MPPT)

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:  

This paper proposes a new stand-alone PMSG-based WECS using battery-assisted qZSI. The proposed battery-assisted qZSI provides the voltage boost and inversion, and energy storage in a single-stage. By introducing the dynamic model of the qZSI with battery, a closed-loop control scheme for both dc-side and ac-side of the qZSI was presented. The magnitude and frequency of the output voltage were effectively controlled through the proposed control scheme under variable wind profile and load conditions. The battery storage system located on quasi-Z-source network balances the stochastic fluctuations of the wind power injected to the load and guarantees an uninterrupted and stable power supply. On the other hand, using a dump load in the proposed system can ensure the stability of the dc-link voltage under over-generation condition of the SWECS. Lack of the dump load makes power balance difficult and can lead to voltage and frequency instability in the over-generation condition, especially when the battery reaches its maximum capacity. The dc-side controller adjusts dsh to manage the battery operation mode and maximum power extraction from the wind. Simulation results verify the performance of the proposed control scheme.

REFERENCES:

[1] C. Lumbreras, J.M. Guerrero, P. García, F. Briz, D.D. Reigosa, Control of a small wind turbine in the high wind speed region, IEEE Trans. Power Electron. 31 (10) (2016) 6980–6991.

[2] A. Kc, J. Whale, T. Urmee, Urban wind conditions and small wind turbines in the built environment: a review, Renew. Energy 131 (2019) 268–283.

[3] H. Li, Z. Chen, Overview of different wind generator systems and their comparisons, IET Renew. Power Gener. 2 (2) (2008) 123–138.

[4] Y. Wang, J. Meng, X. Zhang, L. Xu, Control of PMSG-based wind turbines for system inertial response and power oscillation damping, IEEE Trans. Sustain. Energy 6 (2) (2015) 565–574.

[5] S. Zhang, K. Tseng, D.M. Vilathgamuwa, T.D. Nguyen, X. Wang, Design of a robust grid interface system for PMSG-based wind turbine generators, IEEE Trans. Ind. Electron. 58 (1) (2011) 316–328.