Modeling And Simulation For Voltage Sags/Swells Mitigation Using Dynamic Voltage Restorer (Dvr)

Modeling And Simulation For Voltage Sags/Swells Mitigation Using Dynamic Voltage Restorer (Dvr)

                                

ABSTRACT

This project describes the problem of voltage sags and swells and its severe impact on non linear loads or sensitive loads. The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the protection of sensitive loads from voltage sags and swells. The control of the compensation voltages in DVR based on dqo algorithm is discussed. It first analyzes the power circuit of a DVR system in order to come up with appropriate control limitations and control targets for the compensation voltage control. The proposed control scheme is simple to design. Simulation results carried out by Matlab/Simulink verify the performance of the proposed method .

KEYWORDS

1.     DVR

2. Voltage sags
3. Voltage swells
4. Sensitive load

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM

                                                    Figure 1: Schematic diagram of DVR

CONCLUSION:

The modeling and simulation of a DVR using MATLAB/SIMULINK has been presented. A control system based on dqo technique which is a scaled error of the between source side of the

DVR and its reference for sags/swell correction has been presented. The simulation shows that the DVR performance is satisfactory in mitigating voltage sags/swells.

REFERENCES:

[1] N.G. Hingorani, “Introducing Custom Power in IEEE Spectrum,” 32p, pp. 4l-48, 1995.

[2] IEEE Std. 1159 – 1995, “Recommended Practice for Monitoring Electric Power Quality”.

[3] P. Boonchiam and N. Mithulananthan, “Understanding of Dynamic Voltage Restorers through MATLAB Simulation,” Thammasat Int. J. Sc. Tech., Vol. 11, No. 3, July-Sept 2006.

[4] J. G. Nielsen, M. Newman, H. Nielsen,and F. Blaabjerg, “Control and testing of a dynamic voltage restorer (DVR) at medium voltage level,” IEEE Trans. Power Electron., vol. 19, no. 3,p.806, May 2004.

[5] A. Ghosh and G. Ledwich, “Power Quality Enhancement Using Custom Power Devices,” Kluwer Academic Publishers, 2002.

A Novel Control Method for Shunt Active Power Filters Using SVPWM

A Novel Control Method for Shunt Active Power Filters Using SVPWM

ABSTRACT

A novel control method for shunt active power filters using SVPWM is presented. In the proposed control method, The APF reference voltage vector is generated to instead of the reference current, and the desired APF output voltage is generated by space vector modulation. The control algorithm is simple and can be realized by a low cost controller. The active power filter based on the proposed method can eliminate harmonics, compensate reactive power and balance load asymmetry. A 10kVA laboratory prototype of APF is designed. This prototype adopts the voltage source inverter as the main power circuit and low cost DSP ADMC326 as control core. Simulation and experimental results proves the validity of the analysis and the feasibility of the APF with the proposed control method.

KEYWORDS

1.     Active power filter

2.     SVPWM

3.     DSP

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Figure 1. Control block diagram of proposed active power filter

Figure 2.Configuration of an active power filter using a SVPWM

CONCLUSION:

In this paper, a novel simplified control method, which is suitable for digital control realization, for the active power filter using SVPWM is proposed. This method requires few sensors, and is simple in algorithm, fixed in switching frequency and able to compensate harmonics, reactive power and unbalance loads instantaneously. The performance of active power filters with this method in compensating harmonics is examined and proved to be excellent. The simple algorithm will be able to reduce the complexity of the control circuitry and cut the cost of the system.

REFERENCES:

[1] Singh.B, Al-Haddad.K, Chandra.A, “Review of active filters for power quality improvement”, IEEE Trans. Ind. Electron., (46), 5, Oct, 1999, pp. 960-971

[2] El-Habrouk. M, Darwish. M. K, Mehta. P, “Active power filters—A review,” Proc. IEE—Elect. Power Applicat., vol. 147, no. 5, Sept. 2000, pp. 403–413.

[3] Akagi, H., “New trends in active filters for power conditioning,” IEEE Trans. on Industry Applications, (32), 6, Nov-Dec, 1996, pp. 1312-1322

[4] Peng Fangzheng, “Application issues of active power filters,” IEEE Industry Applications Magazine, v 4, n 5, Sep-Oct, 1998, pp. 21-30

[5] Akagi.H, Kanazawa.Y, and Nabae.A, “Instantaneous reactive power compensators comprising switching device without energy storage components,” IEEE Trans. on Industry Applications, (20), 3, 1984, pp. 625-630.

A Versatile Control Scheme for a Dynamic Voltage Restorer for Power-Quality Improvement

ABSTRACT:

This paper presents a control system based on a repetitive controller to compensate for key power-quality disturbances, namely voltage sag, harmonic voltages, and voltage imbalances, using a dynamic voltage restorer (DVR). The control scheme deals with all three disturbances simultaneously within a bandwidth. The control structure is quite simple and yet very robust; it contains a feed forward term to improve the transient response and a feedback term to enable zero error in steady state. The well-developed graphical facilities available in PSCAD/EMTDC are used to carry out all modeling aspects of the repetitive controller and test system. Simulation results show that the control approach performs very effectively and yields excellent voltage regulation.

KEYWORDS:

1.      Dynamic voltage restorer (DVR)

2.      harmonic distortion

3.      power quality (PQ)

4.      repetitive control

5.      voltage sag

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Test system implemented in PSCAD/EMTDC.

CONCLUSION:

The use of dynamic voltage restorers in PQ-related applications is increasing. The most popular application has been on voltage sags amelioration but other voltage-squality phenomena may also benefit from its use, provided that more robust control schemes than the basic PI controller become available. A case in point is the so called repetitive controller proposed in this paper, which has a fast transient response and ensures zero error in steady state for any sinusoidal reference input and for any sinusoidal disturbance whose frequencies are an integer multiple of the fundamental frequency. To achieve this, the controller has been provided with a feed forward term and feedback term. The design has been carried out by studying the stability of the closed-loop system including possible modeling errors, resulting in a controller which possesses very good transient and steady-state performances for various kinds of disturbances.

A key feature of this control scheme is its simplicity; only one controller is required to eliminate three PQ disturbances, namely, voltage sags, harmonic voltages, and voltage imbalances. The controller can be implemented by using either a stationary reference frame or a rotating reference frame. In this paper, the highly developed graphical facilities available in PSCAD/EMTDC have been used very effectively to carry out all aspects of the system implementation. Comprehensive simulation results using a simple but realistic test system show that the repetitive controller and the DVR yield excellent voltage regulation, thus screening a sensitive load point from upstream PQ disturbances.

  

REFERENCES:

[1] M. H. J. Bollen, “What is power quality?,” Elect. Power Syst. Res., vol. 66, no. 1, pp. 5–14, July 2003.

[2] J. G. Nielsen and F. Blaabjerg, “A detailed comparison of system topologies for dynamic voltage restorers,” IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1272–1280, Sep./Oct. 2005.

[3] V. K. Ramachandaramurthy, A. Arulampalam, C. Fitzer, C. Zhan, M. Barnes, and N. Jenkins, “Supervisory control of dynamic voltage restorers,” Proc. Inst. Elect. Eng., Gen., Transm. Distrib, vol. 151, no. 4, pp. 509–516, Jul. 2004.

[4] P. T. Nguyen and T. K. Saha, “Dynamic voltage restorer against balanced and unbalanced voltage sags: Modelling and simulation,” in Proc. IEEE Power Eng. Soc. General Meeting, Jun. 2004, vol. 1, pp. 639–644, IEEE.

[5] M. H. J. Bollen, Understanding Power Quality Problems: Voltage Sags and Interruptions.. Piscataway, NJ: IEEE Press, 2000.

Soft Computing Techniques for the Control of an Active Power Filter

ABSTRACT:

Non model-based controllers have been explored for the control of a shunt active power filter (APF) designed for harmonic and reactive current mitigation. In this paper, three soft computing techniques viz; fuzzy logic, neural network, and genetic algorithm are used to design alternative control schemes for switching the APF. The models for these control schemes are designed and simulated in MATLAB. A comparative study of the results obtained using these artificial-intelligence-based schemes is presented.

KEYWORDS:

1.      Active power filter (APF)

2.      fuzzy logic

3.      genetic algorithm (GA

4.      neural network

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1. Configuration of the APF.

CONCLUSION:

The overall aim of this paper was to consider methods of achieving better utilization and control of active power filters dealing with harmonic and reactive current compensation. Alternative schemes based on soft computing techniques have been proposed. Non model-based controllers designed around fuzzy logic, neural network, and genetic algorithms were applied to control the switching of the active power filter and were found to provide much better response under varying load and supply conditions.

REFERENCES:

[1] M. El-Habrouk, M. K. Darwish, and P. Mehta, “Active power filters: A review,” Proc. IEEE Electr. Power Appl., vol. 147, no. 5, pp. 403–412, Sep. 2000.

[2] B. Singh, K-Al-Haddad, and A. Chandra, “A review of active filters for power quality improvement,” IEEE Trans. Ind. Electron, vol. 46, no. 5, pp. 960–971, Oct. 1999.

[3] W. M. Grady,M. J. Sanotyj, and A. H. Noyola, “Survey of active power line conditioning methodologies,” IEEE Trans. Power Del., vol. 5, no. 3, pp. 1536–1542, Jul. 1990.

[4] H. L. Jou, J. C. Wu, and H. Y. Chu, “New single-phase active power filter,” Proc. Inst. Elect. Eng., Electr. Power Appl., vol. 141, no. 3, pp. 129–134, May 1994.

[5] K. Chaterjee, B. G. Fernandes, and G. K. Dubey, “An instantaneous reactive volt-ampere compensator and harmonic suppressor system,” IEEE Trans. Power Electron., vol. 14, no. 2, pp. 381–392, Mar. 1999.

Analysis And Design Considerations Of Zero-Voltage And Zero-Current-Switching (ZVZCS) Full-Bridge PWM Converters

Analysis And Design Considerations Of Zero-Voltage And Zero-Current-Switching (ZVZCS) Full-Bridge PWM Converters

ABSTRACT

In this paper, a detailed analysis of the zero voltage and zero-current-switching (ZVZCS) full-bridge PWM converters is performed. The differences of the zero-voltage-switching (ZVS) operation between the conventional ZVS full-bridge PWM converters and the ZVZCS full-bridge PWM converters are analyzed in depth. Circuit parameters that affect the soft-switching conditions are examined and the critical parameters are identified. Based on the analysis, practical design considerations are presented. The analysis and design considerations are verified by experimental results from a 630V/4kW converter operating at 80kHz.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 

                      Fig. 1 Circuit diagram of ZVZCS FB PWM converter

                                                Fig.2 schematic of the converter

CONCLUSION:

In this paper, the zero-voltage and zero-current-switching (ZVZCS) Full-bridge PWM converter was analyzed in depth. The difference of the zero-voltage-switching (ZVS) principle between the conventional ZVS full-bridge PWM converters and the ZVZCS full-bridge PWM converters was analyzed in detail. Circuit parameters affecting the soft switching conditions were examined and the critical parameters were identified. Based on the analysis, practical design considerations were presented. The design procedures can be applied to the various kinds of ZVZCS full-bridge PWM converters [1-5]. The analysis and design considerations were verified by experimental results from a 630V/4kW converter operating at 80kHz.

REFERENCES:

[1] E. S. Kim, K. Y. Cho, et. Al., "An improved ZVZCS PWM FB DC/DC converter using energy recovery snubber," IEEE APEC Rec., 1997, pp.1014-1019.

[2] Jung G. Cho, Ju W. Baek, D.W. Yoo, Hong S. Lee, and Geun H. Rim, "Novel Zero-Voltage and Zero-Current- Switching(ZVZCS) Full Bridge PWM Converter Using Transformer Auxiliary Winding", IEEE PESC Rec., 1997, pp. 227-232.

[3] Jung G. Cho, J. W. Baek, D.W. Yoo, H. S. Lee, and G. H. Rim, "Novel Zero-Voltage and Zero-Current- Switching(ZVZCS) Full Bridge PWM Converter Using a simple auxiliary circuit", IEEE APEC Rec., 1998, pp.834-839.

[4] E. S. Kim, K.Y. Joe and S. G. Park, "An Improved ZVZCS PWM FB DC/DC Converter Using the Modified Energy Recovery Snubber", IEEE APEC Rec., 2000, pp.119-124.

[5] H. S. Choi, J. W. Kim and B.H. Cho, “Novel-Zero- Voltage and Zero-Current-Switching(ZVZCS) Full- Bridge PWM Converter Using Coupled Output Inductor”, APEC 2001. pp.967-973

Current-Fed Dual-Bridge DC–DC Converter

Current-Fed Dual-Bridge DC–DC Converter

ABSTRACT

A new isolated current-fed pulse width modulation dc–dc converter—current-fed dual-bridge dc–dc converter—with small inductance and no dead time operation is presented and analyzed. The new topology has more than 3 smaller inductance than that of current-fed full-bridge converter, thus having faster transient response speed. Other characteristics include simple self-driven synchronous rectification, simple housekeeping power supply, and smaller output filter capacitance. Detailed analysis shows the proposed converter can have either lower voltage stress

on all primary side power switches or soft switching properties when different driving schemes are applied. A 48-V/125-W prototype dc–dc converter with dual output has been tested for the verification of the principles. Both simulations and experiments verify the feasibility and advantages of the new topology.

KEYWORDS

1.     Current-fed

2.     Dc–dc converter

3.     Dead time

4.     Dual-bridge

5.     Full-bridge

6.     Zero voltage switching (ZVS)

SOFTWARE: MATLAB/SIMULINK

CIRCUIT  DIAGRAM:

Fig. 1.Current-fed full-bridge dc–dc converter.

CONCLUSION:

A new topology, isolated current-fed dc–dc converter, characterized by small inductor and no dead time operation, is presented and analyzed. An experimental prototype with 48-V (36–62 V) input and dual outputs of 5 V/20 A and 12.5 V/2 A verifies the validity and merits of the new topology. It has small inductor (corresponding to faster transient response speed), and no RHP zero in its transfer characteristic. Its output ripple current is smaller in contrast to other current-fed topologies [1]–[10], and it has no start-up problem mentioned in [1] and [10]. The main limitations of the new topology are that six power switches are used, and that input voltage range should remain within 2:1 in order to maintain the no dead time property.

REFERENCES:

[1] L. Zhu, K. Wang, F. C. Lee, and J. S. Lai, “New start-up schemes for isolated full-bridge boost converters,” IEEE Trans. Power Electron., vol. 18, no. 4, pp. 946–951, Jul. 2003.

[2] V. Yakushev, V. Meleshin, and S. Fraidlin, “Full-bridge isolated current fed converter with active clamp,” in Proc. IEEE Appl. Power Electron. Conf., 1999, pp. 560–566.

[3] K. Wang, F. C. Lee, and J. Lai, “Operation principles of bi-directional full-bridge dc–dc converter with unified soft-switching scheme and soft-starting capability,” in Proc. IEEE PESC, 2000, pp. 111–118.

[4] P. Tenti, L. Rossetto, L. Malesani, R. Borgatti, and R. Stefani, “Single stage current-fed dc–dc converter with time-sharing control of output voltage and input current,” IEEE Trans. Power Electron., vol. 5, no. 4, pp. 389–397, Oct. 1990.

[5] R. Borgatti, R. Stefani, O. Bressan, F. Bicciato, P. Tenti, and L. Rossetto, “1 kW, 9 kV dc–dc converter module with time-sharing control of oupout voltage and input current,” IEEE Trans. Power Electron., vol.8, no. 4, pp. 606–614, Oct. 1993.

An Improved Power-Quality 30-Pulse AC–DC for Varying Loads

An Improved Power-Quality 30-Pulse AC–DC for Varying Loads

 ABSTRACT

This paper presents the design and analysis of a novel 30-pulse ac–dc converter for harmonic mitigation under varying loads. The proposed 30-pulse ac-dc converter is based on a polygon-connected autotransformer with reduced magnetics. The proposed ac–dc converter is able to eliminate lower than29th order harmonics in the ac supply current. The resulting supply current is near sinusoidal in shape with low total harmonic distortion and a nearly unity power factor. Moreover, the design of an autotransformer is modified to make it suitable for retrofit applications, where converter is found to be suitable for retrofit applications with a large load

KEYWORDS:

1. Autotransformer

2. Multi pulse ac–dc converter

3. Polygon connection

4. power-quality (PQ) improvement.

SOFTWARE: Matlab/Simulink

SCHEMATIC DIAGRAM:

   

     Fig.1 Six-pulse diode-bridge rectifier fed load (topology “A”).

 

                Fig.2.  Proposed  30-pulse ac–dc converter-fed varying load (topology B).

CONCLUSION:

A new 30-pulse ac–dc converter-feeding varying load has been designed, modeled, simulated, and developed to demonstrate its improved performance. The proposed 30-pulse ac–dc converter consists of a reduced rating polygon-connected autotransformer for producing the desired phase shifted voltages and is suitable for retrofit applications, where presently a 6-pulse diode-bridge rectifier is used. It has resulted in the elimination of a lower than 29th harmonic in the supply current. The proposed ac–dc converter has resulted in a THD of supply current of less than 5% in a wide operating range of the load with nearly unity power factor operation. The proposed converter results in the reduction in rating of the magnetics, leading to savings in weight, size, volume, and, finally, the overall cost of the converter system. The results obtained on the developed converter configuration also validate the simulated models and the design procedure

REFERENCES:

[1] B. K. Bose, “Recent advances in power electronics,” IEEE Trans.Power Electron., vol. 7, no. 1, pp. 2–16, Jan. 1992.

[2] G. T. Heydt, Electric Power Quality. West La Fayette, IN: Stars in a Circle Publication, 1991.

[3] M. H. J. Bollen, Understanding Power Quality Problems: Voltage Sags and Interruptions. Piscataway, NJ: IEEE Press, 2000.

[4] A. Ghosh and G. Ledwich, “Power quality enhancement using custom power devices,” in. Norwell, MA: Kluwer, 2002.