Single-Stage Flyback Power-Factor-Correction Front-End for HB LED Application

 ABSTRACT:

This paper presents a single-stage flyback power factor- correction (PFC) front-end for high-brightness light emitting- diode (HB LED) applications. The proposed PFC front-end circuit combines the PFC stage and the dc/dc stage into a single stage. Experimental results obtained on a 78-W (24- V/ 3.25-A) prototype circuit show that at VIN = 110 Vac, the proposed PFC front-end for HB LED applications can achieve an efficiency of 87.5%, a power factor of 0.98, and a total harmonic distortion (THD) of 14% with line-currents harmonics that meet the IEC 61000-3-2 Class C standard.

KEYWORDS:

  1. Driver
  2. high-brightness light emitting diodes (HB LEDs)
  3. power factor correction (PFC)
  4. single-stage
  5. flyback

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. Proposed PFC front-end for HB LED application

 EXPECTED SIMULATION RESULTS:

(a) LB = 83 μH

(b) LB = 166 μH

 Fig. 2. Measured line current and voltage waveforms at VIN = 110 V AC with N1 = N2 = 12 turns, (a) LB = 83 μH;

(a) LB = 83 μH

(b) LB = 166 μH

Fig. 3. Measured current and voltage waveforms, (a) LB = 83 μH; (b) LB = 166 μH. CH1: Current of primary winding N2, CH4: Current of inductor LB; CH3: Drain-to-source voltage of switch Q1. Voltage scale: 200 V/div., current scale: 2 A/div., time scale: 4

Fig. 4. Measured line voltage and current waveforms at VIN = 110 V AC with N1/N2 = 4/26, LB = 166 μH, and LM = 645 μH

Fig. 5. Measured line voltage and current waveforms at VIN = 274 V AC with N1/N2 = 4/26, LB = 415 μH, and LM = 645 μH

CONCLUSION:

 A single-stage flyback power-factor-correction front-end for HB LED application is presented in this paper. With the integration of the PFC stage and dc/dc stage, significant reduction of component count, size, and cost can be achieved. Experimental results obtained on a prototype show that at VIN = 110 V AC, VO = 24 V, and IO = 3.25 A, the proposed PFC front-end for LED driver has achieved an efficiency of around 87.50%, a power factor of 0.98 and a total harmonic distortion (THD) of 14% for the line current with harmonic contents meeting IEC 61000-3-2 Class C standard. Experimental results have also been obtained at high line when the inductance of the input current shaping inductor is increased. Measured output voltage ripple with an actual LED load at VO = 24 V, IO = 3.8 A is less than 20 mV. Therefore, LED strings can be directly driven without a post regulator, improving the efficiency, lowering the cost, and reducing the size.

REFERENCES:

[1] J. Y. Tsao, “Solid-state lighting: lamps, chips, and materials for tomorrow,” IEEE Circuits and Devices Magazine, vol. 20, no. 3, pp. 28 – 37, May-June 2004.

[2] N. Narendran and Y. Gu, “Life of LED-based white light sources,” Journal of Display Technology, vol. 1, no. 1, pp. 167 – 171, Sept. 2005.

[3] T. Komine and M. Nakagawa, “Fundamental analysis for visible-light communication system using LED lights,” IEEE Transactions on Consumer Electronics, vol. 50, no. 1, pp. 100 – 107, Feb. 2004.

[4] Electromagnetic Compatibility (EMC), Part 3-2: Limits – Limits for harmonic current emissions (equipment input current ≤ 16 A per phase), International Standard IEC 61000-3-2, 2001.

[5] ON Semiconductor, “90 W, universal input, single stage, PFC converter,” www.onsemi.com/pub_link/Collateral/ AND8124-D.PDF, Dec. 2003.

Simulation of MRAS-based Speed Sensorless Estimation of Induction Motor Drives using MATLAB/SIMULINK

ABSTRACT
Model Reference Adaptive System (MRAS) based techniques are one of the best methods to estimate the rotor speed due to its performance and straightforward stability approach. These techniques use two different models (the reference model and the adjustable model) which have made the speed estimation a reliable scheme especially when the motor parameters are poorly known or having large variations. The scheme uses the error vector from the comparison of both models as the feedback for speed estimation. Depending on the type of tuning signal driving the adaptation mechanism, there could be a number of schemes available such as rotor flux based MRAS, back e.m.f based MRAS, reactive power based MRAS and artificial neural network based MRAS. All these schemes have their own trends and tradeoffs. In this paper, the performance of the rotor flux based MRAS (RF-MRAS) and back e.m.f based MRAS (BEMFMRAS) for estimating the rotor speed was studied. Both schemes use the stator equation and rotor equation as the reference model and the adjustable model respectively. The output error from both models is tuned using a PI controller yielding the estimated rotor speed. The dynamic response of the RF-MRAS and BEMF-MRAS sensorless speed estimation is examined in order to evaluate the performance of each scheme.

KEYWORDS
1. BEMF-MRAS
2. MRAS
3. Parameter Variations
4. RFMRAS
5. Sensorless Speed
6. Tracking Capability.

SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM

Fig. 1. Basic configuration of MRAS-based speed sensorless estimation scheme.

Fig. 2. Block diagram of RF-MRAS scheme.

Fig. 3. Block diagram of BEMF-MRAS scheme.

SIMULATION RESULTS

Fig. 4. RF-MRAS estimator’s tracking performance at reference speed (a) 100rad/s, (b) 70rad/s and (c) 50rad/s (d)
30rad/s.

Fig. 5. Effect of incorrect setting of RS values to the RF-MRAS estimator’s speed response. (a) Rs (b) Rsnew = 1.1
Rs (C) Rsnew = 1.5 Rs (d) Rsnew = 2 RS.

Fig. 6. BEMF-MRAS estimator’s tracking performance at reference speed (a) 100rad/s, (b) 70rad/s and (c) 50rad/s
(d) 30rad/s.

Fig. 7. Effect of incorrect setting of Rs values to the BEMF-MRAS estimator’s speed response. (a) Rs (b) Rs,ew =
1.1 Rs (c) Rs,ew = 1.5 Rs (d) Rs,ew = 2 Rs.

CONCLUSION
Performance of RF-MRAS and BEMF-MRAS estimators based on the tracking capability and parameter sensitivity was presented. The result shows that the BEMFMRAS estimator is more superior to the RF-MRAS estimator at that particular defined range of reference speeds. This is prior to the elimination of pure integrators used in the RF-MRAS scheme. However, the BEMFMRAS estimator is more difficult to design due to the non-linear effect of the adaptation gain constants. Therefore, as a whole, considering all the key criteria of comparison, it can be concluded that the BEMF-MRAS scheme embrace the requirement as a versatile estimator. It demonstrate good tracking capability and superb in insensitivity to parameter variations.
REFERENCES
[1] M. Ta-Cao, Y. Hori and T. Uchida, “MRAS-based speed sensorless control for induction motor drives using instantaneous reactive power”, IEEE-IES Conference Record, pp. 1717-1422. 2001.
[2] S. Tamai, H. Sugimoto, M. Yano, “Speed-sensorless vector control of induction motor with model reference adaptive system”, Conf. Record of the 1985 IEEE-IAS Annual Meeting, pp. 613-620, 1985.
[3] C. Shauder, “Adaptive speed identification for vector control of induction motor without rotational transducers”, IEEE Trans. Ind. Application, Vol. 28, No. 5, pp. 1054-1061, Sept./Oct. 1992.
[4] Y.P. Landau, “Adaptive Control: The model reference approach”, Marcel Dekker, New York, 1979.
[5] M.N. Marwali, A. Kehyani, “A comparative study of rotor flux based MRAS and back e.m.f based MRAS speed estimators for speed sensorless vector control of induction machine”, IEEEIAS Annual Meeting, New Orleans, Louisiana, pp. 160- 166, 1997.

Comparison of DC/DC Converters in DCM for Reducing Low-Frequency Input Current Ripple of Single-Phase Two-Stage Inverters

ABSTRACT

DC/DC Converters  Single-phase two-stage inverters generally use an intermediate capacitor to buffer the power imbalance between DC input and AC output. However, the resultant low-frequency voltage ripple on this intermediate capacitor may produce low frequency ripple at the source side, especially when the front-end dc/dc converter operates in continuous conduction mode (CCM). Some common solutions to reducing this ripple are feed forward control and power decoupling circuits. Alternatively, this paper analyzes a two-stage inverter where the front-end is a dc/dc converter operating in discontinuous conduction mode (DCM). In general dc/dc converters operating in DCM have inherent natural capability to reduce this low-frequency input current ripple, without needing a sophisticated control or complex circuitry as compared with its CCM operation. Analysis with simulation verification is reported to demonstrate such capability.

KEYWORDS

  1. Dc/ac
  2. Low-frequency ripple
  3. Single-phase
  4. Two stage

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

dc/dc converters

Fig. 1. A simplified power-stage diagram of a single-phase two-stage inverter.

EXPECTED SIMULATION RESULTS

comparison dc dc converters

  • (a) CCM operation: _vin = 3:3V

  • comparison dc dc converters

(b) DCM operation: _vin = 0:88V

Fig. 2. DCM boost front-end converter has lower voltage ripple than CCM.

comparison dc dc converters

Fig. 3. DCM buck-boost front-end converter does not contain low-frequency ripple but only high-frequency ripple.

comparison dc dc converters                                               Fig. 4. SEPIC front-end converter operating in DCM+CCM contains negligible

low-frequency ripple but only high-frequency ripple.

comparison dc dc converters

Fig. 5. High-gain front-end converter operating in DCM does contains

significant low-frequency ripple.

CONCLUSION

This paper analyzes basic and several higher-order front-end dc/dc converters for single-phase two-stage inverter design. Through inspecting the instantaneous average input current of those converters in discontinuous conduction mode (DCM), it has confirmed that buck-boost converter and buck-boost derived converters such as ZETA are free of low-frequency (mainly double ac line frequency) input current ripple due to the lack of direct connection between input and output during switching actions. For boost converter based converters such as SEPIC and C´ uk converters, their input currents contain lower low-frequency content thanks to the cascaded design. For boost converter based high voltage gain converters, its input current may not necessarily reduce the low-frequency content effectively. It depends on how the high-gain sub circuit is constructed and interacts with the input inductor. Further research is necessary to identify suitable converter topologies which have both smooth input current and low frequency content.

REFERENCES

[1] K. Fukushima, I. Norigoe, M. Shoyama, T. Ninomiya, Y. Harada, and K. Tsukakoshi, “Input Current-Ripple Consideration for the Pulse-link DC-AC Converter for Fuel Cells by Small Series LC Circuit,” in 2009 Twenty-Fourth Annual IEEE Applied Power Electronics Conference and Exposition, Feb 2009, pp. 447–451.

[2] L. Jianguo, H. Wenbin, Y. Kai, L. Xiaoyu, W. Fuyun, and W. Junji, “Research on input current ripple reduction of two-stage single-phase PV grid inverter,” in 2014 16th European Conference on Power Electronics and Applications, Aug 2014, pp. 1–8.

[3] B. Ge, Y. Liu, H. Abu-Rub, R. S. Balog, F. Z. Peng, S. McConnell, and X. Li, “Current Ripple Damping Control to Minimize Impedance Network for Single-Phase Quasi-Z Source Inverter System,” IEEE Transactions on Industrial Informatics, vol. 12, no. 3, pp. 1043–1054,

June 2016.

[4] Y. Zhou, H. Li, and H. Li, “A Single-Phase PV Quasi-Z-Source Inverter With Reduced Capacitance Using Modified Modulation and Double- Frequency Ripple Suppression Control,” IEEE Transactions on Power Electronics, vol. 31, no. 3, pp. 2166–2173, March 2016.

[5] D. B. W. Abeywardana, B. Hredzak, and V. G. Agelidis, “An Input Current Feedback Method to Mitigate the DC-Side Low-Frequency Ripple Current in a Single-Phase Boost Inverter,” IEEE Transactions on Power Electronics, vol. 31, no. 6, pp. 4594–4603, June 2016.

[6] H. Hu, S. Harb, N. Kutkut, I. Batarseh, and Z. J. Shen, “A Review of Power Decoupling Techniques for Microinverters With Three Different Decoupling Capacitor Locations in PV Systems,” IEEE Transactions on Power Electronics, vol. 28, no. 6, pp. 2711–2726, June 2013.
[7] M. A. Vitorino, L. F. S. Alves, R. Wang, and M. B. de Rossiter Corrła, “Low-Frequency Power Decoupling in Single-Phase Applications: A Comprehensive Overview,” IEEE Transactions on Power Electronics, vol. 32, no. 4, pp. 2892–2912, April 2017.
[8] Z. Chao, H. Xiangning, and Z. Dean, “Design and control of a novel module integrated converter with power pulsation decoupling for photovoltaic system,” in 2008 International Conference on Electrical Machines and Systems, Oct 2008, pp. 2637–2639.
[9] D. Debnath and K. Chatterjee, “A buck-boost integrated full bridge inverter for solar photovoltaic based standalone system,” in 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), June 2013, pp. 2867– 2872.
[10] J. Kan, S. Xie, Y. Wu, Y. Tang, Z. Yao, and R. Chen, “Single-Stage and Boost-Voltage Grid-Connected Inverter for Fuel-Cell Generation System,” IEEE Transactions on Industrial Electronics, vol. 62, no. 9, pp. 5480–5490, Sept 2015.
[11] D. Zhou, “Synthesis of PWM dc-to-dc power converters,” Ph.D. dissertation, California Institute of Technology, Pasadena, California, 1996.

 

Speed response of brushless DC motor using fuzzy PID controller under varying load condition

ABSTRACT

The increasing trend towards usage of precisely controlled, high torque, efficient and low noise motors for dedicated applications has attracted the at tention of researcher in Brushless DC (BLDC) motors. BLDC motors can act as an acceptable alternative to the conventional motors like Induction Motors, Switched Reluctance Motors etc. This paper presents a detailed study on the performance of a BLDC motor supplying different types of loads, and at the same time, deploying different control techniques. An advance Fuzzy PID controller is compared with the commonly used PID controller. The load variations considered are of the most common types, generally encountered in practice. A comparison has been carried out in this paper by observing the dynamic speed response of motor at the time of application as well as at the time of removal of the load. The BLDC motors suffer from a major drawback of having jerky behavior at the time of load removal. The study reveals that irrespective of the type of controller used, the gradual load variation produces better results as against sudden load variations. It is further observed that in addition to other dynamic features, the jerks produced at the time of load removal also get improved to a large extent with Fuzzy PID controller. The speed torque characteristics un raveled the fact that the jerks are minimum at the time of gradual load removal with Fuzzy PID controller in place. An attempt has been made to define these jerks by ‘Perturbation Window’.

KEYWORDS:

  1. BLDC motor
  2. Proportional-integral-derivative (PID) controller
  3. Fuzzy (FL) controller
  4. MATLAB/SIMULINK

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:


 Fig.1.Block diagram of BLDC motor drive.

  EXPERIMENTAL RESULTS:

Fig.2.(a) Speed response curve (b) current response curve (c) torque response curve with PID controller under gradual application and removal of load.

Fig.3.(a) Speed response curve (b) current response curve (c) torque response curve with Fuzzy PID controller under sudden application and removal of load.

Fig.4.(a) Speed response curve (b) current response curve (c) torque response curve with Fuzzy PID controller. under sudden application and removal of load

Fig.5.(a) Speed response curve (b) current response curve (c) torque response curve with Fuzzy PID controller under sudden application and removal of load.

Fig.6.(a) Speed response curve (b) current response curve (c) torque response curve with Fuzzy PID controller under gradual application and removal of load.

CONCLUSION

A model is developed in this paper for BLDC Drive using MATLAB/SIMULINK to analyze its performance with PID controller and with Fuzzy PID Controller when the motor is subjected to the most commonly encountered sudden load variations as well as gradual load variations under constant speed operation. The BLDC drive gives better performance if the load is changed gradually. Further, it is found that the transient response of the drive in terms of overshoot, under shoot, peak time and settling time are improved with the use of FPID. Speed torque characteristics of The drive are also used for all the conditions to assess the overall behavior of the machine. The commonly experienced major drawback of the jerks of BLDC motors at the time of load removal has been found to get reduced by 50% incase of sudden load removal and by about 80% incase of gradual load removal by applying FPID controller as against the use of classical PID controller.

REFERENCES

Arulmozhiyal, R., Kandiban, R., 2012. Design of Fuzzy PID controller for Brushless DC motor. In: International conference on Computer Communication and Informatics (ICCCI—2012), Jan.10–12, Coimbatore, INDIA.

Baldursson,S.,2005. BLDC Motor Modelling and Control—A MATLAB/Simulink Implementation, Master Thesis.

Dorf,C.,Richard,C.,Robert Bishop,H.,2001.Modern control systems,9thed.Prentice Hall Inc.,New Jersey-07458,USA,Chapters 1,5,pp.1–23,pp.173–206.

Farouk,Naeim,Bingqi,Tian,2012.Application of self-tuning Fuzzy PID controller on the AVR system. In: IEEE Conference of Mechatronics and Automation,August5–8,Chengdu,China.

Gupta,D.,2016.Speed control of Brushless DC motor using Fuzzy PID controller.11–12 March KNIT, IndiaIn: IEEE conference on Emerging trends in Electrical, Electronics & Sustainable Energy System,Volume2,pp.221–224.

Microgrid connected PV-Based Sources

ABSTRACT

Microgrid connected This article studies the control configuration of a microgrid-connected photovoltaic (MCPV) source. In the control of an MCPV, maximum power point (MPP) tracking, droop control, and dc bus voltage regulation are the main required functions. To increase their penetration in the microgrid, MCPV sources have to participate in the microgrid’s frequency regulation. Consequently, MCPVs may be forced to depart from MPP for short periods of time. In this article, a control method is proposed to operate the MCPV in the MPP at all times except when there is a need to stabilize the frequency. The method achieves this objective autonomously without the need to change the control configuration. This method is explained, and its superiority over other controllers to achieve the same objective is investigated. The suggested control configurations are validated through simulation studies and experiments.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

microgrid connected

(a)

(b)

Fig 1.The hybrid control configuration of the MCPVs: (a) the MPP control configuration and (b) the droop control configuration.

 EXPERIMENTAL RESULTS:

Fig 2.The responses of the dc bus voltage and the reactive  power of the hybrid MCPVs: (a) the dc bus voltage of the  MCPVs and (b) the reactive power of source1, source2, and the hybrid MCPVs.

Fig 3.The frequencies of source1, source2, and the hybrid MCPVs

Fig4.The responses of the dc bus voltage and the reactive power of the universal MCPVs: (a) the dc bus voltage of the MCPV  and (b) the reactive power of source1, source2, and the hybrid MCPV.

 

Fig5.The responses of the power and dp-dv for the universal MCPVs: (a) the power provided by source2 and the universal MCPVs and (b) the value of dp/dv of the universal MCPVs.

Fig6.The frequencies of source1, source2, and the universal MCPVs.

Fig7.The power-voltage characteristics of the simulated PV.

Fig 8.The hybrid MCPV experimental results: (a) the power of source2 and (b) the value of dp/dv of the hybrid MCPVs.

 CONCLUSION

In this article, the control strategies for the MCPVs were investigated. The considered MCPVs comprised the PV source: dc/dc and dc/ac converters. The need for a new control configuration for MCPV sources to participate in the frequency and voltage regulation in addition to the MPPT controller was justified. One way to control the MCPVs was to switch between two controllers, one for MPPT and the other to perform droop control. The combination of the two controllers is called a hybrid controller. The hybrid controller suf In this article, the control strategies for the MCPVs were investigated. The considered MCPVs comprised the PV source: dc/dc and dc/ac converters. The need for a new control configuration for MCPV sources to participate in the frequency and voltage regulation in addition to the MPPT controller was justified. One way to control the MCPVs was to switch between two controllers, one for MPPT and the other to perform droop control. The combination of the two controllers is called a hybrid controller. The hybrid controller suffered from two problems. The first was the need for an external switching signal to switch from one controller to the other, indicating a lack of plug-and-play capability. The second problem was the poor transient in the dynamics whenever there was a change in the controller or the load. A new controller was then proposed that achieved the MPPT, droop control, and dc bus voltage regulation without the need to switch between different configurations. The proposed controller was denoted as the universal controller. In this controller, a dc bus regulator controls the dc bus voltage by adjusting the duty ratio of the dc/dc converter, while both the droop controller and the MPPT controller drive the dc/ ac inverter phase. The controllers were tuned in such a way that, whenever there is a significant change in the load, the droop controller response is dominant to stabilize the frequency of the microgrid. Later, the MPPT moves the operating point to the MPP automatically but smoothly to avoid any disruption in the frequency. The proposed controllers were tested by simulations and experiments, where the validity of the method was verified in terms of stabilizing the frequency, maximizing the power production, regulating the dc bus voltage, and operating autonomously without the need for an external switching decision.

REFERENCES

[1] M. Amin, “Toward self-healing energy infrastructure systems,” IEEE Comput. Appl. Power, vol. 14, no. 1, pp. 20–28, 2001.

[2] G. Venkataramanan and C. Marnay, “A larger role for microgrids,” IEEE Power Energy Mag., vol. 6, no. 3, pp. 78–82, 2008.

[3] M. Prodanovic and T. Green, “High-quality power generation through distributed control of a power park microgrid,” IEEE Trans. Ind. Electron., vol. 53, no. 5, pp. 1471–1482, 2006.

[4] S.-J. Ahn, J.-W. Park, Il-Y. Chung, S.-Il Moon, S.-H. Kang, and S. Nam, “Power-sharing method of multiple distributed generators considering control modes and configurations of a microgrid,” IEEE Trans. Power Delivery, vol. 25, no. 3, pp. 2007–2016, 2010.

[5] F. A. Farret and M. G. Simoes, Integration of Alternative Sources of Energy. Hoboken, NJ: Wiley, 2006.

A Novel Three-Phase Three-Leg AC/AC Converter Using Nine IGBTs

ABSTRACT:

This paper proposes a novel three-phase nine-switch ac/ac converter topology. This converter features sinusoidal inputs and outputs, unity input power factor, and more importantly, low manufacturing cost due to its reduced number of active switches. The operating principle of the converter is elaborated; its modulation schemes are discussed. Simulated semiconductor loss analysis and comparison with the back-to-back two-level voltage source converter are presented. Finally, experimental results from a 5-kVA prototype system are provided to verify the validity of the proposed topology.

 

KEYWORDS:

  1. AC/AC converter
  2. pulse width modulation (PWM)
  3. reduced switch count topology

 

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:Fig: 1 B2B 2L-VSC.

Fig: 2 Proposed nine switch ac to ac converter with a quasi dc link

 

EXPECTED SIMULATION RESULTS:

  

Fig. 3. Measured rectifier and inverter waveforms (CF-mode operation). (a) Input and output voltages. (b) Voltage spectrum. (c) Input and output currents.

Fig. 4. Measured waveforms and spectrum (VF mode operation). (a) Input and output voltages. (b) Spectrum.

Fig. 5. Measured waveforms when the inverter output frequency has a step increase from 30 to 120 Hz, while the rectifier input frequency remains at 60 Hz. (a) Input and output voltages. (b) Input and output currents.

 

CONCLUSION:

A novel nine-switch PWMac/ac converter topology was proposed in this paper. The topology uses only nine IGBT devices for ac to ac conversion through a quasi dc-link circuit. Compared with the conventional back-to-back PWM VSC using 12 switches and the matrix converter that uses 18, the number of switches in the proposed converter is reduced by 33% and 50%, respectively. The proposed converter features sinusoidal inputs and outputs, unity input power factor, and low manufacturing cost. The operating principle of the converter was elaborated, and modulation schemes for constant and VF operations were developed. Simulation results including a semiconductor loss analysis and comparison were provided, which reveal that the proposed converter, while working in CF mode, has an overall higher efficiency than the B2B 2L-VSC at the expense of uneven loss distribution. However, the VF-mode version requires IGBT devices with higher ratings and dissipates significantly higher losses, and thus, is not as attractive as its counterpart. Experimental verification is carried out on a 5-kVA prototype system.

 

REFERENCES:

 Wu, High-power Converters and AC Drives. Piscataway, NJ: IEEE/Wiley, 2006.

  • Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, “A review of three-phase improved power quality AC– DC converters,” IEEE Trans. Ind. Electron., vol. 51, no. 3, pp. 641–660, Jun. 2004.
  • Blaabjerg, S. Freysson, H. H. Hansen, and S. Hansen, “A new optimized space-vector modulation strategy for a component-minimized Voltage source inverter,” IEEE Trans. Power Electron., vol. 12, no. 4, pp. 704–714, Jul. 1997.
  • L. A. Ribeiro, C. B. Jacobina, E. R. C. da Silva, and A. M. N. Lima, “AC/AC converter with four switch three phase structures,” in Proc. IEEE PESC, 1996, vol. 1, pp. 134–139.

Fault Ride-Through of a DFIG Wind Turbine Using a Dynamic Voltage Restorer During Symmetrical and Asymmetrical Grid Faults

ABSTRACT:

 The application of a dynamic voltage restorer (DVR) connected to awind-turbine-driven doubly fed induction generator (DFIG) is investigated. The setup allows the wind turbine system an uninterruptible fault ride-through of voltage dips. The DVR can compensate the faulty line voltage, while the DFIG wind turbine can continue its nominal operation as demanded in actual grid codes. Simulation results for a 2 MW wind turbine and measurement results on a 22 kW laboratory setup are presented, especially for asymmetrical grid faults. They show the effectiveness of the DVR in comparison to the low-voltage ride-through of the DFIG using a crowbar that does not allow continuous reactive power production.

 KEYWORDS:

  1. Doubly fed induction generator (DFIG)
  2. Dynamic voltage restorer (DVR)
  3. Fault ride-through and wind energy

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fault Ride-Through of a DFIG

Fig. 1. Schematic diagram of DFIG wind turbine system with DVR.

 EXPECTED SIMULATION RESULTS:

 

Fig. 2. Simulatin of DFIG performance with crowbar protection during 37 % two-phase voltage dip. (a) Line voltage. (b) DVR voltage. (c) Stator voltage. (d) Stator current. (e) RSC current. (f) Crowbar current. (g) Mechanical speed. (h) Active and reactive stator power. (i) Active and reactive DVR power.

Fig. 3. Simulation of DFIG performance with DVR protection during 37 % two-phase voltage dip. (a) Line voltage. (b) DVR voltage. (c) Stator voltage. (d) Stator current. (e) RSC current. (f) Crowbar current. (g) Mechanical speed. (h) Active and reactive stator power. (i) Active and reactive DVR power.

Fig. 4. Measurement results for DFIG with crowbar protection: (a) stator

voltages, (b) stator currents, and (c) rotor currents.

Fig. 5. Measurement results for DFIG with DVR protection: (a) line voltages, (b) DVR voltages, (c) stator voltages, (d) stator currents, and (e) rotor currents.

CONCLUSION:

The application of a DVR connected to a wind-turbine-driven DFIG to allow uninterruptible fault ride-through of grid voltage faults is investigated. The DVR can compensate the faulty line voltage, while the DFIG wind turbine can continue its nominal operation and fulfill any grid code requirement without the need for additional protection methods. The DVR can be used to protect already installed wind turbines that do not provide sufficient fault ride-through behavior or to protect any distributed load in a microgrid. Simulation results for a 2 MW wind turbine under an asymmetrical two-phase grid fault show the effectiveness of the proposed technique in comparison to the low-voltage ridethrough of the DFIG using a crowbar where continuous reactive power production is problematic. Measurement results under transient grid voltage dips on a 22 kW laboratory setup are presented to verify the results.

REFERENCES:

[1] M. Tsili and S. Papathanassiou, “A review of grid code technical requirements for wind farms,” Renewable Power Generat., IET, vol. 3, no. 3, pp. 308–332, Sep. 2009.

[2] R. Pena, J. Clare, and G. Asher, “Doubly fed induction generator using back-to-back pwm converters and its application to variable-speed windenergy generation,” Electr. Power Appl., IEE Proc., vol. 143, no. 3, pp. 231–241, May 1996.

[3] S.Muller,M.Deicke, andR.DeDoncker, “Doubly fed induction generator systems for wind turbines,” IEEE Ind. Appl.Mag., vol. 8, no. 3, pp. 26–33, May/Jun. 2002.

[4] J. Lopez, E. Gubia, P. Sanchis, X. Roboam, and L. Marroyo, “Wind turbines based on doubly fed induction generator under asymmetrical voltage dips,” IEEE Trans. Energy Convers., vol. 23, no. 1, pp. 321–330, Mar. 2008.

[5] M. Mohseni, S. Islam, and M. Masoum, “Impacts of symmetrical and asymmetrical voltage sags on dfig-based wind turbines considering phaseangle jump, voltage recovery, and sag parameters,” IEEE Trans. Power Electron., to be published.

Design and Simulation of three phase Inverter for grid connected Photovoltaic systems

ABSTRACT:

Grid connected photovoltaic (PV) systems feed electricity directly to the electrical network operating parallel to the conventional source. This paper deals with design and simulation of a three phase inverter in MATLAB SIMULINK environment which can be a part of photovoltaic grid connected systems. The converter used is a Voltage source inverter (VSI) which is controlled using synchronous d-q reference frame to inject a controlled current into the grid. Phase lock loop (PLL) is used to lock grid frequency and phase. The design of low pass filter used at the inverter output to remove the high frequency ripple is also discussed and the obtained simulation results are presented.

 

KEYWORDS:

  • VSI Inverter
  • PLL
  • d-q reference frame
  • Grid connected system.

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

grid tied pv system

Fig.1 Block diagram of the system

 

EXPECTED SIMULATION RESULTS:

Fig.2 Output frequency obtained from PLL

Fig.3 Sin & Cos wave generated by PLL

Fig.4 Synchronization between reference grid voltage & PLL output voltage

 

Fig.5 Three phase voltage fed by inverter to grid

Fig .6 Average active power fed to grid is 1000 Watt

 

CONCLUSION:

The design of the system is carried out for feeding 1KW power to the grid The Inverter is controlled in order to feed active power to the grid, using synchronous d-q transformation. PLL is used to lock grid frequency and phase. The phase detection part of PLL is properly done by using dq transformation in the three phase system. The FFT analysis of the inverter output current shows that the THD is within limits and the controlled injected current generates three phase balance current which controls power at the output of the transformer. To simulate the actual grid connected PV system, the PV model, dc to dc converter model and the control of the dc to dc converter should be included in place of the battery source.

 

REFERENCES:

  • Soeren Baekhoej, John K Pedersen & Frede Blaabjerg, ―A Review of single phase grid connected inverter for photovoltaic modules,‖ IEEE transaction on Industry Application , Vol. 41,pp. 55 – 68, Sept 2005
  • Milan Pradanovic& Timothy Green, ―Control and filter design of three phase inverter for high power quality grid connection, ― IEEE transactions on Power Electronics,18. pp.1- 8, January 2003
  • C Y Wang,Zhinhong Ye& G.Sinha, ― Output filter design for a grid connected three phase inverter,‖Power electronics Specialist Conference, pp.779-784,PESE 2003
  • Samul Araujo& Fernando Luiz, ― LCL fiter design for grid connected NPC inverters in offshore wind turbins,‖ 7th International conference on Power Electronics, pp. 1133-1138, October 2007.
  • Frede Blaabjerg , Remus Teodorescu and Marco Liserre, ―Overview of control & grid synchronization for distributed power generation systems,‖ IEEE transaction on Industrial Electronics, Vol. 53, pp. 500 – 513,Oct- 2006

 

A STATCOM-Control Scheme for Grid Connected Wind Energy System for Power Quality Improvement

ABSTRACT:

Injection of the wind power into an electric grid affects the power quality. The performance of the wind turbine and thereby power quality are determined on the basis of measurements and the norms followed according to the guideline specified in International Electro-technical Commission standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operation and these are measured according to national/international guidelines. The paper study demonstrates the power quality problem due to installation of wind turbine with the grid. In this proposed scheme STATic COMpensator (STATCOM) is connected at a point of common coupling with a battery energy storage system (BESS) to mitigate the power quality issues.

The battery energy storage is integrated to sustain the real power source under fluctuating wind power. The STATCOM control scheme for the grid connected wind energy generation system for power quality improvement is simulated using MATLAB/SIMULINK in power system block set. The effectiveness of the proposed scheme relives the main supply source from the reactive power demand of the load and the induction generator. The development of the grid co-ordination rule and the scheme for improvement in power quality norms as per IEC-standard on the grid has been presented.

 

KEYWORDS:

  1. International electro-technical commission (IEC)
  2. power quality
  3. wind generating system (WGS)

 

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

  statcom

Fig.1.System operational scheme in grid system.

 

EXPECTED SIMULATION RESULTS:

  

Fig. 1. Three phase injected inverter Current.

Fig. 2. (a) Source Current. (b) Load Current. (c) Inverter Injected Current. (d) Wind generator (Induction generator) current.


Fig. 3. (a) DC link voltage. (b) Current through Capacitor, 
STATCOM output voltage.

Fig. 5. Supply Voltage and Current at PCC.


Fig.6.(a) Source Current. (b) FFT of source current.                

Fig.7.(a) Source Current. (b) FFT of source current

 

CONCLUSION:

The paper presents the STATCOM-based control scheme for power quality improvement in grid connected wind generating system and with non linear load. The power quality issues and its consequences on the consumer and electric utility are presented. The operation of the control system developed for the STATCOM-BESS in MATLAB/SIMULINK for maintaining the power quality is simulated. It has a capability to cancel out the harmonic parts of the load current. It maintains the source voltage and current in-phase and support the reactive power demand for the wind generator and load at PCC in the grid system, thus it gives an opportunity to enhance the utilization factor of transmission line. The integrated wind generation and STATCOM with BESS have shown the outstanding performance. Thus the proposed scheme in the grid connected system fulfills the power quality norms as per the IEC standard 61400-21.

 

REFERENCES:

 Sannino, “Global power systems for sustainable development,” in IEEE General Meeting, Denver, CO, Jun. 2004.

  • S. Hook, Y. Liu, and S. Atcitty, “Mitigation of the wind generation integration related power quality issues by energy storage,” EPQU J., vol. XII, no. 2, 2006.
  • Billinton and Y. Gao, “Energy conversion system models for adequacy assessment of generating systems incorporating wind energy,” IEEE Trans. on E. Conv., vol. 23, no. 1, pp. 163–169, 2008, Multistate.
  • Wind Turbine Generating System—Part 21, International standard-IEC 61400-21,
  • Manel, “Power electronic system for grid integration of renewable energy source: A survey,” IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1002–1014, 2006, Carrasco.

Improving the Dynamic Performance of Wind Farms with STATCOM

ABSTRACT:

When integrated to the power system, large wind farms can pose voltage control issues among other problems. A thorough study is needed to identify the potential problems and to develop measures to mitigate them. Although integration of high levels of wind power into an existing transmission system does not require a major redesign, it necessitates additional control and compensating equipment to enable (fast) recovery from severe system disturbances. The use of a Static Synchronous Compensator (STATCOM) near a wind farm is investigated for the purpose of stabilizing the grid voltage after grid-side disturbance such as a three phase short circuit fault. The strategy focuses on a fundamental grid operational requirement to maintain proper voltages at the point of common coupling by regulating the voltage. The DC voltage at individual wind turbine (WT) inverters is also stabilized to facilitate continuous operation of wind turbines  during disturbances.

 

KEYWORDS:

  1. Wind turbine
  2. Doubly-fed Induction Generator
  3. STATCOM
  4. Three phase fault
  5. Reactive power

 

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

wind farm with statcom

Fig. 1. Block diagram of a Doubly-fed induction generator

Fig. 2 Test System

EXPECTED SIMULATION RESULTS: 

Fig. 3. Voltage at the fault bus (Load bus) , Voltage at the fault bus (Zoomed version)

Fig. 4. Reactive power in the system with no compensating device, Reactive power in the system with mechanically switched capacitors

Fig. 5. Reactive and active power of the 25 MVA STATCOM for Case 3, AC and DC busbar voltages of the STATCOM for Case III.

Fig. 6. Reactive and active powers of only the STATCOM for Case 4, Reactive power and terminal voltage of only the the MSC for Case 4.

Fig. 7. Reactive powers of the system with a STATCOM and MSC

Fig. 8. Reactive power of the 125 MVA STATCOM for Case 5.

 

CONCLUSION:

Wind turbines have to be able to ride through a fault without disconnecting from the grid. When a wind farm is connected to a weak power grid, it is necessary to provide efficient power control during normal operating conditions and enhanced support during and after faults. This paper explored the possibility of connecting a STATCOM to the wind power system in order to provide efficient control. An appropriately sized STATCOM can provide the necessary reactive power compensation when connected to a weak grid. Also, a higher rating STATCOM can be used for efficient voltage control and improved reliability in grid connected wind farm but economics limit its rating. Simulation studies have shown that the additional voltage/var support provided by an external device such as a STATCOM can significantly improve the wind turbine’s fault recovery by more quickly restoring voltage characteristics. The extent to which a STATCOM can provide support depends on its rating. The higher the rating, the more support provided. The interconnection of wind farms to weak grids also influences the safety of wind turbine generators. Some of the challenges faced by wind turbines connected to weak grids are an increased number and frequency of faults, grid abnormalities, and voltage and frequency fluctuations that can trip relays and cause generator heating.

 

REFERENCES:

  • http://www.awea.org/newsroom/releases/Wind_Power_Capacity_012307. html, accessed Nov. 2007.
  • Sun, Z. Chen, F. Blaabjerg, “Voltage recovery of grid-connected wind turbines with DFIG after a short-circuit fault,” 2004 IEEE 35th Annual Power Electronics Specialists Conf., vol. 3, pp. 1991-97, 20-25 June 2004.
  • Muljadi, C.P. Butterfield, “Wind Farm Power System Model Development,” World Renewable Energy Congress VIII, Colorado, Aug- Sept 2004.
  • M. Muyeen, M.A. Mannan, M.H. Ali, R. Takahashi, T. Murata, J. Tamura, “Stabilization of Grid Connected Wind Generator by STATCOM,” IEEE Power Electronics and Drives Systems Conf., Vol. 2, 28-01 Nov. 2005.
  • Saad-Saoud, M.L. Lisboa, J.B. Ekanayake, N. Jenkins, G. Strbac, “Application of STATCOMs to wind farms,” IEE Proceedings – Generation, Transmission, Distribution, vol. 145, pp.1584-89, Sept 1998.