Design of a SRF Based MC UPQC Used for Load Voltage Control in Parallel Distribution Systems

ABSTRACT:

This paper deals with a new design dynamic model of synchronous-reference- frame (SRF)-based control in three phase system under different load considerations to improve power quality by using power conditioner with multi converters. The proposed MCUPQC system can regulate the load voltages/bus voltages on Parallel power distribution systems under balanced and distorted load conditions and obtain the state space model for MC-UPQC. The simulation results to support the SRF-based control method presented in this paper is done using Matlab/Simulink.

 

KEYWORDS:

  1. Power quality (PQ)
  2. Active power filter (APF)
  3. Synchronous reference frame (SRF) and multi converter
  4. Unified power-quality conditioner (MC-UPQC)

  

SOFTWARE: MATLAB/SIMULINK

  

BLOCK DIAGRAM:

Fig.1.The single line diagram of conventional MC-UPQC

 

 EXPECTED SIMULATION RESULTS:

Fig. 2.a and b. the phase bus voltage, VS1 and load voltage VL1

Fig. 3.c and d. the phase bus voltage, VS2 and load voltage VL2

Fig.4.a & b. the phase Source Current, IS1 and Load CurrentIL1

Fig. 5 and 6 .a, b and c. The phase bus voltage, injected voltage and load Voltages

Fig. 7.a, b and c. The phase Source Currents (IS1), load Currents (IL1) and DC Capacitor Voltage(VDC).

Fig. 8.a, b, c, d, e and f. the phase bus voltage (VS1), load Voltages (VL1), load Voltages (VL2), the phase source currents (IS1), load Currents (IL1) and DC Capacitor Voltage (VDC).

  

CONCLUSION:

In this paper the SRF Based control MC-UPQC for regulates of load voltage and load current in adjacent parallel feeder has been proposed and compared to a conventional MC-UPQC, the proposed control topology is capable of fully protecting critical and sensitive loads against sudden changing loads, voltage sag/ swells, and fault interruption in two-feeder distribution systems. The performance of the SRF based MC-UPQC is tested under various disturbance conditions.

 

REFERENCES:

  • G. Hingorani “Introducing custom power,” IEEE spectrum, vol.32, June 1995, pp. 41-48.
  • Ray Arnold “Solutions to Power Quality Problems” power engineering Journal, Volume 15; Issue: 2 April 2001, pp: 65-73.
  • John Stones and Alan Collision “Introduction to Power Quality” power engineering journal, Volume 15; Issue 2, April 2001, pp: 58- 64.
  • Fujita and H. Akagi, “The unified power quality conditioner: The integration of series and shunt active filter,” IEEE Trans. Power Electron. , vol. 13, no. 2, pp. 315–322, Mar. 1998..
  • Gyugyi, C. D. Schauder, S. L. Williams, T. R. Rietman, D. R. To rjerson, and A. Edris, “The unified power flow controller: A new approach to power transmission control,” IEEE Trans. Power Del. , vol. 10, no. 2, pp. 1085–1097, Apr. 1995.

Multiconverter Unified Power Quality Conditioning System Using Artificial Neural Network Technique

ABSTRACT:

This paper presents a new unified power-quality conditioning system (MC-UPQC), capable of simultaneous compensation for voltage and current in multibus/multifeeder systems. In this configuration, one shunt voltage-source converter (shunt VSC) and two or more series VSCs exist. The system can be applied to adjacent feeders to compensate for supply-voltage and load current imperfections on the main feeder and full compensation of supply voltage imperfections on the other feeders. In the proposed configuration, all converters are connected back to back on the dc side and share a common dc-link capacitor. Therefore, power can be transferred from one feeder to adjacent feeders to compensate for sag/swell and interruption. The performance of the MC-UPQC as well as the adopted control algorithm is illustrated by simulation. The present work study the compensation principle and different control strategies used here are based on PI & ANN Controller of the MC-UPQC in detail. The results obtained in MATLAB/PSCAD on a two-bus/two-feeder system show the effectiveness of the proposed configuration.

KEYWORDS:

  1. power quality (PQ) unified power-quality conditioner (UPQC)
  2. voltage-source converter (VSC)
  3. Aritifical neural network- ANN

  

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

Fig.1.Block diagram of MC_UPQC with STATCOM

  

EXPECTED SIMULATION RESULTS:

Fig2. BUS1 voltage,series compensating voltage, and load voltage in feeder1

Fig3.BUS2 voltage,series compensating voltage, and load voltage in feeder2

Fig4.nonlinear load current,compensating current,feeder1 current and capacitor voltage

Fig5.Bus1 loadcurrent,Bus2 load current,Bus1 load voltage,Bus2 load voltage wave forms using ANN controller in Mc- UPQC

Fig 6. Three phase source voltage(Va,Vb,Vc) wave form

Fig.7. load current with ANN controller

Fig.8 Load Voltage with ANN Controller

CONCLUSION:

The present topology illustrates the operation and control of Multi Converter Unified Power Quality Conditioner (MCUPQC). The system is extended by adding a series VSC in an adjacent feeder. A suitable mathematical have been described which establishes the fact that in both the cases the compensation is done but the response of ANN controller is faster and the THD is minimum for the both the voltage and current in sensitive/critical load. The device is connected between two or more feeders coming from different substations. A non-linear/sensitive load L-1 is supplied by Feeder-1 while a sensitive/critical load L-2 is supplied through Feeder-2. The performance of the MC-UPQC has been evaluated under various disturbance conditions such as voltage sag/swell in either feeder, fault and load change in one of the feeders. In case of voltage sag, the phase angle of the bus voltage in which the shunt VSC (VSC2) is connected plays an important role as it gives the measure of the real power required by the load. The MC-UPQC can mitigate voltage sag in Feeder-1 and in Feeder-2 for long duration.

 

REFERENCES:

  • Hamid Reza Mohammadi, Ali Yazdian Varjani, and Hossein Mokhtari,“Multiconverter Unified Power-Quality Conditioning System: MC- UPQC” IEEE RANSACTIONS ON POWER DELIVERY, VOL. 24,NO. 3, JULY 2009.
  • Rezaeipour and A.Kazemi, “Review of Novel control strategies for UPQC” Internal Journal of Electric and power Engineering 2(4) 241-247, 2008.
  • Ravi Kumar and S.Siva Nagaraju“Simulation of DSTATCOM and DVR in power systems” Vol. 2, No. 3, June 2007 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences.
  • V.Kasuni Perera” Control of a Dynamic Voltage Restorer to compensate single phase voltage sags” Master of Science Thesis, Stockholm, Sweden 2007.
  • Basu, S. P. Das, and G. K. Dubey, “Comparative evaluation of two models of UPQC for suitable interface to enhance power quality,” Elect.Power Syst. Res., pp. 821–830, 2007.

Convertible Unified Power Quality Conditioner to mitigate voltage and current imperfections

ABSTRACT

 This paper proposes a novel convertible unified power quality conditioner (CUPQC) by employing three voltage source converters (VSCs) which are connected to a multi-bus/multifeeder distribution system to mitigate current and voltage imperfections. The control performance of the VSCs is characterized by a minimum of six circuit open/close switches configurable in a minimum of seventeen combinations to enable the CUPQC to operate as shunt and series active power filters (APFs), unified power quality conditioner (UPQC), interline UPQC (IUPQC), multi-converter UPQC (MC-UPQC) and generalized UPQC (GUPQC). The simulation and compensation performance analysis of CUPQC are based on PSCAD/EMTDC.

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM

Fig.1 Schematic representation of proposed CUPQC

 EXPECTED SIMULATION RESULTS

 Fig.2. Feeder1 (a) Load current (b) Source voltage

        

 Fig.3. Feeder1 (a) Compensation currents (b) Compensation voltages

Fig.4. Feeder1 (a) Source currents (b) Load voltages

Fig.5. Feeder1 THD spectrum (a) Currents (b) Voltages

Fig.6. Feeder3 source voltage

Fig.7. Feeder3 compensation voltage

Fig.8. Feeder3 load voltages

Fig.9. Feeder3 voltage THD before and after compensation

Fig.10. (a) Feeder1source voltage (b) Feeder2 source voltage (c) Feeder3 load current

Fig.11. (a) Feeder1 compensation voltages (b) Feeder2 compensation

voltages(c) Feeder3 compensation currents

Fig.12. (a) Feeder1 load voltages (b) Feeder2 load voltages (c) Feeder3 source Currents

Fig.13. THD before and after compensation (a) Feeder1 voltage (b) Feeder2 voltage (c) Feeder3 current

Fig.14. RMS voltage (a) Feeder1 (b) Feeder2

CONCLUSION

In this paper the performance of the proposed CUPQC in three modes of operation as UPQC, MC-UPQC and GUPQC on a multi-bus/multi-feeder distribution system is validated by simulation results. The operating modes of the novel power quality conditioner in 17 different modes for compensation of currents and voltage interruptions are clearly explained. As an extension to this analysis, the authors are working on a model for characterization and testing of the proposed CUPQC.

REFERENCES

 [1] H. Akagi, and H. Fujita “A new power line conditioner for harmonic compensation in power systems,” IEEE Trans. Power Del., vol. 10, 1995.

[2] P. Mitra, and G. Kumar, “An adaptive control strategy for DSTATCOM applications in an electric ship power system,” IEEE Trans. Power Electro., vol. 25, no. 1, pp. 95 –104, Jan. 2010.

[3] M. J. Newman, D. G. Holmes, J. G. Nielsen, and F. Blaabjerg, “A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level” IEEE Trans. Ind. Appl., vol. 41, no. 6, pp. 1744 – 1753, Nov. 2005.

[4] H. Fujita, and H. Akagi, “The unified power quality conditioner: The integration of series and shunt-active filters,” IEEE Trans. Power Electron., vol. 13, no. 2, pp. 315 – 322, Mar. 1998.

[5] V. Khadkikar, and A. Chandra, “A novel structure for three-phase four wire distribution system utilizing unified power quality conditioner,” IEEE Trans. Ind. Appl., vol. 45, no. 5, pp. 1897 – 1902, Sept./Oct. 2009.

Control of a Small Wind Turbine in the High Wind Speed Region

ABSTRACT:

This paper proposes a new soft-stalling control strategy for grid-connected small wind turbines operating in the high and very high wind speed conditions. The proposed method is driven by the the rated current/torque limits of the electrical machine and/or the power converter, instead of the rated power of the connected load, which is the limiting factor in other methods. The developed strategy additionally deals with the problem of system startup preventing the generator from accelerating to an uncontrollable operating point under a high wind speed situation. This is accomplished using only voltage and current sensors, not being required direct measurements of the wind speed nor the generator speed. The proposed method is applied to a small wind turbine system consisting of a permanent magnet synchronous generator and a simple power converter topology. Simulation and experimental results are included to demonstrate the performance of the proposed method. The paper also shows the limitations of using the stator back-emf to estimate the rotor speed in permanent magnet synchronous generators connected to a rectifier, due to significant d-axis current at high load.

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1. Schematic representation of the wind energy generation system: a) Wind turbine, generator and power converter; b) Block diagram of the boost converter control system; c) Block diagram of the H-bridge converter control system.

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Simulation result showing the behavior of the proposed method under increasing wind conditions (10 m/s, 17 m/s from 10 s, and 33 m/s from 13s): a) rectifier voltage command (v_ r ), rectifier voltage (vr) and minimum rectifier voltage command (v_ r min); b) boost current (ib), filtered boost current (~i b), current limit (ilimit) and MPPT current target (imppt); c) turbine torque (Tt) and generator torque (Tg); d) mechanical rotor speed (!rm).

 Fig. 3. Simulation result showing the behavior of the proposed method under decreasing wind conditions (30 m/s, 21 m/s from 4.5 s, and 8.5 m/s from 7s): a) rectifier voltage command (v_ r ), rectifier voltage (vr) and minimum rectifier voltage command (v_ r min); b) boost current (ib), filtered boost current (~I b), current limit (ilimit) and MPPT current target (imppt); c) turbine torque (Tt) and generator torque (Tg); d) mechanical rotor speed (!rm).

Fig. 4. Experimental results showing the behavior of the propose method under increasing wind conditions (10 m/s, 17 m/s from 10 s, and 33 m/s from 13 s): a) rectifier voltage command (v_ r ), rectifier voltage (vr) and minimum rectifier voltage command (vr min); b) boost current (ib), filtered boost current (~I b), current limit (ilimit) and MPPT current target (imppt); c) mechanical rotor speed (!rm).

 Fig. 5. Experimental results showing the behavior of the propose method under decreasing wind conditions (30 m/s, 21 m/s from 4.5 s, and 8.5 m/s from 9 s): a) rectifier voltage command (v_ r ), rectifier voltage (vr) and minimum rectifier voltage command (vr min); b) boost current (ib),filtered boost current (~I b), current limit (ilimit) and MPPT current target (imppt); c) mechanical rotor speed (!rm).

CONCLUSION:

The operation of small wind turbines for domestic or small business use is driven by two factors: cost and almost unsupervised operation. Specially important is the turbine operation and protection under high wind speeds, where the turbine torque can exceed the rated torque of the generator. This paper proposes a soft-stall method to decrease the turbine torque if a high wind speed arises and, as a unique feature, the method is able to early detect a high wind condition at startup keeping the turbine/generator running at low rotor speed avoiding successive start and stop cycles. The proposed method uses only voltage and current sensors typically found in small turbines making it an affordable solution. Both simulation and experimental results demonstrate the validity of the proposed concepts. This paper also shows that commonly used machine and rectifier models assuming unity power factor do not provide accurate estimations of the generator speed in loaded conditions, even if the resistive and inductive voltage drop are decoupled, due to the significant circulation of d-axis current if a PMSG is used. This paper proposes using a pre-commissioned look-up table whose inputs are both the rectifier output voltage and the boost current.

REFERENCES:

[1] W. Kellogg, M. Nehrir, G. Venkataramanan, and V. Gerez, “Generation unit sizing and cost analysis for stand-alone wind, photovoltaic, and hybrid wind/PV systems,” IEEE Transactions on Energy Conversion, vol. 13, no. 1, pp. 70–75, Mar. 1998.

[2] P. Gipe, Wind Power: Renewable Energy for Home, Farm, and Business, 2nd Edition. Chelsea Green Publishing, Apr. 2004.

[3] A. C. Orrell, H. E. Rhoads-Weaver, L. T. Flowers, M. N. Gagne, B. H. Pro, and N. A. Foster, “2013 Distributed Wind Market Report,” Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Tech. Rep., 2014. [Online]. Available: http://www.osti.gov/scitech/biblio/1158500

[4] J. Benjanarasut and B. Neammanee, “The d-, q- axis control technique of single phase grid connected converter for wind turbines with MPPT and anti-islanding protection,” in 2011 8th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON). IEEE, May 2011, pp. 649–652.

[5] M. Arifujjaman, “Modeling, simulation and control of grid connected Permanent Magnet Generator (PMG)-based small wind energy conversion system,” in Electric Power and Energy Conference (EPEC), 2010 IEEE, Aug. 2010, pp. 1 –6.

 

 

Synchronization and Reactive Current Support of PMSG based Wind Farm during Severe Grid Fault

ABSTRACT:

Grid codes require wind farm to remain on-grid and inject specific reactive current when grid fault occurs. To satisfy the requirements, reactive power devices such as the static synchronous compensator (STATCOM) are usually used in modern wind farms. In order to produce reactive currents, the wind energy generation system (WECS) and the STATCOM are normally controlled with the phase locked loop (PLL)-oriented vector control methods. Due to the active power imbalance between the generation and consumption, the wind farm has the risk of losing synchronization with the grid under severe fault conditions. This paper analyzes the dynamic synchronization mechanism and stability criteria of the wind farm and proposes a coordinated current control scheme for the WECS and the STATCOM during severe grid fault period. The synchronization stability of both the WECS and the STATCOM is remained by the active power balancing control of the wind farm. The control objectives of the generator- and grid-side converters for the WECS are swapped to avoid the interaction between the dc-link voltage control loop and the synchronization loop. The synchronized STATCOM produces additional reactive currents to help the wind farm meet the requirements of the grid code. Effectiveness of the theoretical analyses and the proposed control method are verified by simulations.

 

KEYWORDS:

  1. Low voltage ride through (LVRT)
  2. Permanent magnet synchronous generator (PMSG)
  3. Wind farm
  4. Coordinated current control

 

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

Fig. 1. Configuration of the PMSG-based wind farm

  

EXPECTED SIMULATION RESULTS:

Fig. 2. System response of the PMSG-based wind farm with conventional control strategy during severe fault

Fig. 3. System response of the PMSG-based wind farm with proposed strategy during severe fault

 

CONCLUSION:

This paper studied the LOS mechanism and the coordinating LVRT scheme of the PMSG based wind farm when severe grid voltage dip occurs. The following conclusions can be derived from the theoretical analyses and simulation verification:

(1) Variable-speed wind turbines and STATCOM both have the LOS risk when the grid voltage dip is severe.

(2) The proposed active power balancing control scheme which relies on the frequency dynamic of the PLL can achieve the synchronization stability of the WECS. However, reactive current capability of the WECS would be sacrificed to implement such scheme.

(3) The coordinated current control between the PMSG based WECS and the STATCOM can achieve both the synchronization stability and the reactive current support according to the grid code under severe grid fault. The analysis results and proposed scheme are also available for the LVRT of other renewable energy conversion systems.

(4) It should be pointed out that this paper focuses on the symmetrical fault conditions. In practical applications, unsymmetrical faults occur more often than symmetrical ones. Some Europe grid codes, such as “VDE-AR-N 4120” code in Germany, are requiring the WECS to provide negative sequence current compensation during unsymmetrical fault period. In such cases, the advanced PLL, such as the second order generalized integrator (SOGI) PLL [31], should be employed to separate the positive and negative sequence components from the grid voltage. The advanced PLLs have much more complicated structures and models compared with the conventional one as indicated in this paper. Also the synchronization stability should be discussed in both positive and negative sequences. By further considering the coupling of the PLL and control loops during grid faults similarly with the case discussed in this paper, the synchronization issue would be more complicated. More studies are expected in this issue and would be our future work.

 

REFERENCES:

  • BDEW Technical Guideline, Generating Plants Connected to the Medium- Voltage Network [EB/OL], June 2008 issue.
  • Grid code-high and extra high voltage, E. ON Netz GmbH, 2006. Tech. Rep., [EB/OL].
  • Geng, C. Liu and G. Yang. LVRT Capability of DFIG-Based WECS Under Asymmetrical Grid Fault Condition [J]. IEEE Transactions on Industrial Electronics, vol. 60, no. 6, pp. 2495-2509, June 2013.
  • Chinchilla M., Arnaltes S., Burgos J. C. Control of permanent-magnet generators applied to variable-speed wind-energy systems connected to the grid [J]. IEEE Transactions on Energy Conversion, 2006, 21(1): 130-5.
  • Conroy J. F., Watson R. Frequency Response Capability of Full Converter Wind Turbine Generators in Comparison to Conventional Generation [J]. IEEE Transactions on Power Systems, 2008, 23(2): 649-56.

Control of permanent magnet synchronous generator-based stand-alone wind energy conversion system

ABSTRACT:

This study deals with an implementation of a constant speed permanent magnet synchronous generator (PMSG)-based three-phase stand-alone wind energy conversion system (SWECS). The voltage and frequency controller is realised using only a single voltage source converter (VSC) and a battery energy storage system (BESS). The BESS is used to provide load leveling under varying wind speeds and to control frequency of SWECS. The voltage of PMSG is regulated under varying wind speeds and loads by supplying the reactive power from VSC. The performance of SWECS is demonstrated as a load leveller, a load balancer, a harmonic compensator and a voltage and frequency controller.

 

SOFTWARE: MATLAB/SIMULINK

  

CIRCUIT DIAGRAM:

Fig. 1 Proposed system configurations of VFC for PMSG-based SWECS

a System configuration of VFC for PMSG-based 3P3W SWECS

b System configuration of VFC for PMSG-based 3P4W SWECS

  

EXPECTED SIMULATION RESULTS:

Fig. 2 Simulated performance of VFC under fall in wind speed (12 –10 m/s) at fixed balanced linear loads

Fig. 3 Simulated performance of VFC under rise in wind speed (10 –12 m/s) at balanced linear loads

 

CONCLUSION:

A VFC for a PMSG in stand-alone WECS has been designed, modelled and developed for feeding three-phase consumer loads. The VFC has been realised using a VSC and a battery energy storage system. A new control strategy for VFC has been realised using IcosF algorithm and implemented for PMSG-based SWECS. The performance of VFC has been found satisfactory under varying wind speeds and loads. The VFC has performed the functions of load leveller, load balancer and a harmonic eliminator along with VFC.

REFERENCES:

  • Patel, M.R.: ‘Wind and solar power systems’ (CRC Press, Washington, DC, 2006, 2nd edn.)
  • David, S.B., Jenkins, N., Bossanyi, E.: ‘Wind energy handbook’ (John Wiley & Sons. Ltd., 2001)
  • Simoes, M.G., Farret, F.A.: ‘Renewable energy systems’ (CRC Press, Florida, 2004)
  • Lai, L.L., Chan, T.F.: ‘Distributed generation -induction and permanent magnet generators’ (John Wiley and Sons Ltd., 2007
  • Heier, S.: ‘Grid integration of wind energy conversion systems’ (Wiley, New York, 1998)

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
  5. Speed wind turbine
  6. Voltage and frequency control

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

Figure 1.Control Structure of a PMSG based standalone variable speed wind turbine.

 

EXPECTED SIMULATION RESULTS:

 

Figure 2. Response of the system for a step change of wind speed from 10 m/s to 12 m/s to 9 m/s to 10 m/s.

Figure 3. Voltage and current responses at a constant load.

Figure 4. Frequency response, DC link voltage and modulation index at a constant load.

Figure 5. Voltage and current responses when load is reduced by 50%.

Figure.6. Frequency response, DC link voltage and modulation index when load is reduced by 50%.

 

CONCLUSION:

Control strategy for a standalone 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 output 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:

  • 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.
  • 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.
  • F. Chan, L. L. Lai, “Permanenet-magnet machines for distributed generation: a review,” in proc. 2007 IEEE power engineering annual meeting, pp. 1-6.
  • 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.

Battery Energy Storage System for Variable Speed Driven PMSG for Wind Energy Conversion System

ABSTRACT:

There are many loads such as remote villages, islands, etc. that are located far away from the main grid. These loads require stand-alone generating system, which can provide constant voltage and frequency for local electrification. Locally available wind power can be used in such off-grid systems. As the wind speed is variable, an AC-DC-AC conversion system is required to convert variable voltage and variable frequency power generation to constant voltage and constant frequency source. Further, as the wind power as well as load is variable there is a need of energy storage device that take care of the load mismatch. In this paper, a standalone wind energy conversion system (WECS) using a variable speed permanent magnet synchronous generator (PMSG) is proposed with a battery energy storage system.

KEYWORDS:

  1. Wind energy conversion system
  2. Isolated system
  3. BESS
  4. Permanent magnet synchronous generator

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig.1 PMSG with PWM rectifier with battery for storing the extra wind energy

EXPECTED SIMULATION RESULTS:

 Fig.2. Variation of wind speed, load voltages, load currents, generator power, battery power, load power battery current and DC link voltage.

 CONCLUSION:

The isolated operation of wind energy conversion system requires AC-DC-AC interface with the capability of converting variable voltage variable frequency to constant voltage constant frequency source. In addition the power balancing has to be done with some energy storage system, According to the proposed topology, battery energy storage system provides power balance between the generated power and the load. The power mismatch is absorbed by the BESS.

REFERENCES:

[1] Bhim Singh and Gaurav Kumar Kasal, “Solid-State Voltage and Frequency Controller for a stand alone wind power generating system,” IEEE Trans. Power Electronics, vol. 23, no.3, pp.1170–1177, 2008.

[2] Bhim Singh and Gaurav Kumar Kasal, “Voltage and Frequency Controller for a 3-Phase 4-Wire Autonomous Wind Energy Conversion System” accepted for publication in IEEE Trans. on Energy Conversion.

[3] Ghosh and G. Ledwich, Power Quality Enhancement Using Custom Power Devices. Kulwer Academic, 2002.

[4] Gipe, P. Wind power’, Chelsea Green Publishing Company, Post Mills, Vermount, USA,1995.

[5] Rai, G.D. (2000) ‘Non conventional energy sources’, Khanna Publishers, 4th Edition, New Delhi (India)

An Energy Management Scheme with Power Limit Capability and an Adaptive Maximum Power Point Tracking for Small Standalone PMSG Wind Energy Systems

ABSTRACT:

Due to its high energy generation capability and minimal environmental impact, wind energy is an elegant solution to the growing global energy demand. However, frequent atmospheric changes make it difficult to effectively harness the energy in the wind because maximum power extraction occurs at a different operating point for each wind condition. This paper proposes a parameter independent intelligent power management controller that consists of a slope-assisted maximum power point tracking (MPPT) algorithm and a power limit search (PLS) algorithm for small standalone wind energy systems with permanent synchronous generators. Unlike the parameter independent perturb & observe (P&O) algorithms, the proposed slope-assisted MPPT algorithm preempts logical errors attributed to wind fluctuations by detecting and identifying atmospheric changes. The controller’s PLS is able to minimize the production of surplus energy to minimize the heat dissipation requirements of the energy release mechanism by cooperating with the state observer and using the slope parameter to seek the operating points that result in the desired power rather than the maximum power. The functionality of the proposed energy management control scheme for wind energy systems is verified through simulation results and experimental results.

KEYWORDS:

  1. Wind energy
  2. Maximum power point tracking
  3. Energy management
  4. Power electronics

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig 1 System diagram with the proposed management control algorithm

 EXPECTED SIMULATION RESULTS:

 

 Fig 2 Performance of the standard fixed-step size P&O algorithm (average power captured = 1066 W).

Fig 3 Performance of the standard variable-step size P&O algorithm (average power captured = 1106 W).

Fig 4 Performance of the slope-assisted MPPT algorithm (1238 W).

Fig 5 Power coefficient performance of the fixed-step size P&O, variable step size P&O, and the slope assist MPPT (comparison performed under atmospheric identical conditions as depicted in Fig.20).

CONCLUSION:

In this paper, an intelligent parameter-independent power management controller has been presented for standalone offgrid small wind energy systems. With the state observer presiding over the slope-assisted MPPT and the PLS in the proposed controller, the convergence times to the desired operating points is reduced and the logical errors are minimized by identifying the changes in wind conditions. Being applicable for both grid-connected and standalone wind systems, the slope assist MPPT increases a wind system’s MPP search efficiency and enables the wind system to actively adapt to its changing behavior and wind conditions. The PLS algorithm was designed to complement the slope assist MPPT for standalone wind systems that have limited energy storage and use energy dissipation mechanisms to disperse surplus energy. Rather than focusing on capturing maximum power, the power limit search focuses on reducing the size and heat requirements of the energy dissipation mechanism by minimizing surplus power generation as desired. The operating principles of the proposed PLS and MPPT control techniques have been discussed in this paper. Simulation results on a 3kW system and experimental results on a proof-of-concept prototype with a wind turbine emulator have been provided to highlight the merits of this work.

REFERENCES:

[1] Global Wind Energy Council, “Global Wind Report – Anual Market Update 2012,” 2013.

[2] Global Wind Energy Council, “Global Wind 2011 Report,” 2012.

[3] Canadian Wind Energy Association, “Canadian Wind Energy Association,” [Online]. Available: www.canwea.ca.

[4] Q. Wang and L. Chang, “An Intelligent Maximum Power Extraction Algorithm for Inverter-Based Variable Speed Wind Turbine Systems,” IEEE Transactions on Power Electronics, vol. 1, September 2004, pp. 1242-1249.

[5] E. Koutroulis and K. Kalaitzakis, “Design of a Maximum Power Tracking System for Wind Energy Conversion Applications,” IEEE Transaction on Industrial Electronics, vol. 53, no. 2, April 2006, pp. 486-494.

An Autonomous Wind Energy Conversion System with Permanent Magnet Synchronous Generator

ABSTRACT:

This paper deals with a permanent magnet synchronous generator (PMSG) based variable speed autonomous wind energy conversion system (AWECS). Back back connected voltage source converter (VSC) and a voltage source inverter (VSI) with a battery energy storage system (BESS) at the intermediate dc link are used to realize the voltage and frequency controller (VFC). The BESS is used for load leveling and to ensure the reliability of the supply to consumers connected at load bus under change in wind speed. The generator-side converter operated in vector control mode for achieving maximum power point tracking (MPPT) and to achieve unity power factor operation at PMSG terminals. The load-side converter is operated to regulate amplitude of the load voltage and frequency under change in load conditions. The three-phase four wire consumer loads are fed with a non-isolated star-delta transformer connected at the load bus to provide stable neutral terminal. The proposed AWECS is modeled, design and simulated using MATLAB R2007b simulink with its sim power system toolbox and discrete step solver.

KEYWORDS:

  1. Battery
  2. Permanent Magnet Synchronous Generator
  3. Star-delta Transformer
  4. Voltage Source Converters
  5. Maximum Power Point Tracking
  6. Wind Energy

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1 Proposed control scheme of VFC for PMSG based AWECS

 EXPECTED SIMULATION RESULTS:

 

 Fig. 2 Performance of Controller during fall in wind speed

Fig. 3 Performance of Controller during rise in wind speed

Fig. 4 Performance of Controller at fixed wind speed and balanced/unbalanced non-linear loads

CONCLUSION:

 A new configuration of voltage and frequency controller for a permanent magnet synchronous generator based variable speed autonomous wind energy conversion system has been designed modeled and its performance is simulated. The VFC has used two back-back connected VSC’s and BESS at intermediate dc link. The GSC has been controlled in vector controlled to achieve MPPT, unity power factor operation of PMSG. The LSI has been controlled to maintain amplitude of load voltage and its frequency. The VFC has performed the function of a load leveler, a load balancer, and a harmonic eliminator.

REFERENCES:

[1] J. F. Gieras and M. Wing, Permanent Magnet Motor Technology – Design and Application, Marcel Dekker Inc., New York, 2002.

[2] M. Kimura, H. Koharagi, K. Imaie, S. Dodo, H. Arita and K. Tsubouchi, “A permanent magnet synchronous generator with variable speed input for co-generation system,” IEEE Power Engineering Society Winter Meeting, 2001, vol. 3, 28 Jan.-1 Feb. 2001, pp. 1419 – 1424.

[3] T.F. Chan, L.L. Lai, Yan Lie-Tong, “Performance of a three-phase AC generator with inset NdFeB permanent-magnet rotor,” IEEE Trans. Energy Conversion, vol.19, no.1, pp. 88- 94, March 2004.

[4] T.F. Chan, W. Wang, L.L. Lai, “Analysis and performance of a permanent-magnet synchronous generator supplying an isolated load,” IET, Electric Power Applications, vol. 4, no. 3, pp.169-176, March 2010.

[5] K. Amei, Y. Takayasu, T. Ohji and M. Sakui, “A maximum power control of wind generator system using a permanent magnet synchronous generator and a boost chopper circuit,” Proc. of the Power Conversion Conference, PCC Osaka 2002, vol. 3, 2-5 April 2002, pp. 1447 – 1452.