Control of the Dynamic Voltage Restorer to Improve Voltage Quality

ABSTRACT:

In this study a method is proposed in order to improve the voltage compensation performance of Dynamic Voltage Restorer by using Self Tuning Filter. The proposed control method gives an adequate voltage compensating even for 50% voltage sag and distorted voltage conditions. The proposed DVR control method is modeled using MATLAB/SIMULINK and tested both in off-line and real-time environment. Results are then presented as a verification of the proposed method.

KEYWORDS:

1.      DVR; voltage sag

2.      Voltage harmonics

3.      STF

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

EXPECTED SIMULATION RESULTS:

CONCLUSION:

This paper shows the effectiveness of implementing STF in the traditional control method of DVR to compensate the distorted and unbalanced grid voltage condition as well as sudden drop or increase in grid voltage. Performance of the improved method is tested both in off-line and real-time mode. Results show that the proposed method can significantly improve the performance of the DVR and thus the load does not sense any kind of grid voltage disturbances.

Moreover, the grid voltage harmonics are effectively suppressed on the load terminal.

REFERENCES:

[1] M. Ramasamy, S. Thangavel, Experimental verification of PV based Dynamic Voltage Restorer With Significant Energy Conservation, Electrical Power and Energy Systems 49 (2013) 296-307.

[2] O. S. Senturk, A. M Hava, "High-Performance Harmonic Isolation and Load Voltage Regulation of the Three-Phase Series Active Filter Utilizing the Waveform Reconstruction Method," IEEE Transactions on Industry Applications, vol.45, no.6, pp.2030,2038, Nov.-dec. 2009.

[3] M. Abdusalam, P. Poure, S. Karimia, S. Saadate, "New Digital Reference Current Generation for Shunt Active Power Filter under Distorted Voltage Conditions", Electric Power Systems Research, vol. 79, pp 759-76, 2009.

[4] A. Ghamri , M. T. Benchouia & A. Golea "Sliding-Mode Control Based Three-Phase Shunt Active Power Filter", Simulation and Experimentation, Electric Power Components and Systems, 40:4, 383- 398, Jan. 2012.

Incremental Fuzzy PI Control of a HVDC Plant

Incremental Fuzzy PI Control of a HVDC Plant

ABSTRACT:

This paper investigates a Fuzzy Logic (FL) based current controller for a High Voltage Direct Current (HVDC) plant connected to a weak AC system under the EMTP RV simulation environment. A typical HVDC system is modeled with a detailed representation of the converter, converter controls and AC system. An Incremental Fuzzy Gain Scheduling Proportional and Integral Controller (IFGSPIC) is used for the rectifier current control. The current error and its derivative are taken as two parameters necessary to adapt the proportional (P) and integral (I) gains of the controller based on fuzzy reasoning. Two different fuzzy rule bases are designed to tune the PI gains independently. The fuzzy control rules and analysis of IFGSPIC are presented. To improve performance, the IFGSPIC is designed like a hybrid controller that combines the advantages of a FL and conventional PI controllers. During transient states, the PI gains are adapted by the IFGSPIC to damp out undesirable oscillations around the set point and reduce settling time. During the steady state, the controller is automatically switched to the conventional PI controller to maintain the control stability and accuracy. Performance evaluation under AC fault and set-point step change is studied. A performance comparison between the conventional PI controller and hybrid IFGSPIC is made. Results from the various tests show that the proposed controller outperforms its conventional counterpart in each case.

KEYWORDS:

1.     FL Controller

2.     Gain scheduling

3.     EMTP RV

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 EXPECTED SIMULATION RESULTS:

CONCLUSION:

In this paper, a method combining FL with a conventional PI controller is proposed and applied to the current controller of a HVDC plant. A performance comparison between the two types of controllers showed that the robustness and adaptation of the proposed FL controller is better. For a strong AC system at the HVDC converter, both controllers have an acceptable performance. But when the AC system is weak (an increasingly important requirement for such plants), the HVDC system is prone to collapse with the conventional controller while the FL controller has a satisfactory performance.

REFERENCES:

1. V. K. Sood, “HVDC and FACTs Controllers,” Kluwer Academic Publishers, 2004, ISBN 1-4020-7890-0.

[2]. P.K.Dash, A.C.Liew, and A. Routray, “High-performance controllers for HVDC transmission links.” IEE, Proc.-Gener. Transm. Distrib., Vol. 141, No. 5, September 1994.

[3]. S. Haykin, “Neural Networks: A Comprehensive Foundation.” 2^nd ed. New York: Prentice Hall, 1995.

[4]. Li-Xin Wang, “A Course in Fuzzy Systems and Control,” Prentice Hall PTR, 1997.

[5]. V.K. Sood, N. Kandil, R.V. Patel, and K. Khorasani, “Comparative evaluation of neural network-based and PI current controllers for HVDC transmission.”, IEEE Transactions on Power Electronics, Vol. 9, No. 3, pp. 288-296, May 1994.

Application of Artificial Neural Networks for Shunt APF Control

Application of Artificial Neural Networks for

Shunt APF Control

ABSTRACT:

Artificial Neural Network (ANN) is becoming an attractive estimation and regression technique in many control applications due to its parallel computing nature and high learning capability. There has been a lot of effort in employing the ANN in shunt active power filter (APF) control applications. Adaptive Linear Neuron (ADALINE) and feed-forward Multilayer Neural Network (MNN) are the most commonly used ANN techniques to extract fundamental and/or harmonic components present in the non-linear currents. This paper aims to provide an in-depth understanding on realizing ADALINE and feed-forward MNN based control algorithms for shunt APF. A step-by-step procedure to implement these ANN based techniques, in Matlab/ Simulink environment, is provided. Furthermore, a detailed analysis on the performance, limitation and advantages of both methods is presented in the paper. The study is supported by conducting both simulation and experimental validations.

KEYWORDS:

1.     Shunt APF

2.     ANN

3.     ADALINE

4.     Feed-forward MNN.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 CONTROL BLOCK DIAGRAM:

 EXPECTED SIMULATION RESULTS:

CONCLUSION:

In this paper, two widely used ANN based shunt APF control strategies, namely the ADALINE and feed-forward MNN, are investigated. A simple step by step procedure is provided to implement each method in Matlab/Simulink environment. The ADALINE is trained online by the LMS algorithm, while the MNN is trained offline using the SCG back propagation algorithm to extract the fundamental load active current magnitude. The performance of these ANN based shunt APF controllers is evaluated through detailed simulation and experimental studies. Based on the study conducted in this paper, it is observed that the ADALINE based control technique performs better than the feed-forward MNN. For untrained load scenario, the feed-forward MNN

fails to extract the fundamental component, resulting in overcompensation from the dc link PI regulator. On contrary, the online adaptiveness of ADALINE makes it applicable to any load condition.

REFERENCES:

[1] P. Kanjiya, V. Khadkikar, and H. H. Zeineldin, “A Noniterative Optimized Algorithm for Shunt Active Power Filter Under Distorted and Unbalanced Supply Voltages,” IEEE Trans. Ind. Electron., vol.60, no.12, pp.5376,5390, Dec. 2013.

[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] M. Popescu, A. Bitoleanu, and V. Suru, “A DSP-Based Implementation of the p-q Theory in Active Power Filtering Under Nonideal Voltage Conditions,” IEEE Trans. Ind. Informat., vol.9, no.2, pp.880,889, May 2013.

[4] V. Silva, J. G. Pinto, J. Cabral, J. L. Afonso, and A. Tavares, “Real time digital control system for a single-phase shunt active power filter,” in Conf. Rec. INDIN, 2012, pp.869,874.

[5] A. Hamadi, S. Rahmani, K. Al-Haddad, “Digital Control of a Shunt Hybrid Power Filter Adopting a Nonlinear Control Approach,” IEEE Trans. Ind. Informat., vol.9, no.4, pp.2092,2104, Nov. 2013.

Modeling and Simulation of All-Electric Ships With Low-Voltage DC Hybrid Power Systems

ABSTRACT:

DC hybrid power systems are of interest for future low emission, fuel-efficient vessels. In spite of the advantages they offer on board a ship, they result in a complex, interconnected system, which requires effective analysis tools to enable a full realization of the advantages. Modelling and simulation are essential tools to facilitate design, analysis, and optimization of the system. This paper reviews modelling of hybrid electric ship components including mechanical and electrical elements. Power electronic converters are modelled by non-linear averaging methods to suit system-level studies. A unified model for bidirectional converters is proposed to avoid transitions between two separate models. A simulation platform using the derived models is developed for the system-level analysis of hybrid electric ships. Simulation results of power sharing among two diesel generators, a fuel cell module, and an energy storage system are presented for three modes of operation.

KEYWORDS:

1.      DC distribution systems

2.      Modeling

3.      Simulation

4.      Transportation.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

                               Fig. 1. Single-line diagram overview of a typical shipboard dc hybrid electric power system.

CONCLUSION:

Modeling of an all-electric ship with low-voltage dc power system was carried out. Averaging methods were used to model the power electronic converters by neglecting high-frequency switching behaviour inorder to reduce the computation burden and time. A simulation platform was developed using the derived models of different components for system-level studies. The simulation results for a sailing profile of an all-electric ship showed how the dynamic behaviors of different mechanical and electrical variables can be observed and studied by using the simulation program. Providing significant savings in terms of time and computational intensity, the presented simulation platform could be useful for long-term or repetitive simulations that are required for research on all-electric ship dc power systems.

REFERENCES:

[1] A. K. Adnanes, “Maritime electrical installations and diesel electric propulsion,” ABB AS Marine, Oslo, Norway, 2003.

[2] J. M. Apsley, A. Gonzalez-Villasenor, M. Barnes, A. C. Smith, S.Williamson, J. D. Schuddebeurs, P. J. Norman, C. D. Booth, G. M. Burt, and J. R. McDonald, “Propulsion drive models for full electric marine propulsion systems,” IEEE Trans. Ind. Appl., vol. 45, no. 2, pp. 676–684, Mar. 2009.

[3] S. De Breucker, E. Peeters, and J. Driesen, “Possible applications of plugin hybrid electric ships,” in Proc. IEEE Electric Ship Technol. Symp., Apr. 20–22, 2009, pp. 560–567.

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

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 magnetic. The proposed ac–dc converter is able to eliminate lower than 29th 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 presently a 6-pulse diode bridge rectifier is used. To validate the proposed approach, various power-quality indices are presented under varying loads. The proposed ac–dc converter is found to be suitable for retrofit applications with a large load variation and where harmonic reduction is more stringent. The laboratory prototype of the proposed autotransformer-based 30-pulse ac–dc converter is developed and test results are presented which validate the developed design procedure and the simulation models of this ac–dc converter.

KEYWORDS:

1.      Auto transformer

2.      Multipulse ac–dc converter

3.      Polygon connection

4.      Power-quality (PQ) improvement.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT  DIAGRAM:

EXPECTED SIMULATION RESULTS:

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 LaFayette, 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.

[5] F. J. M. de Seixas and I. Barbi, “A12 kWthree-phase lowTHD rectifier with high frequency isolation and regulated dc output,” IEEE Trans. Power Electron., vol. 19, no. 2, pp. 371–377, Mar. 2004.

Elimination of Harmonics in a Five-Level Diode-Clamped Multilevel Inverter Using Fundamental Modulation

ABSTRACT:

In this study, elimination of harmonics in a five level diode-clamped multilevel inverter (DCMLI) has been implemented by using fundamental modulation switching. The proposed method eliminates harmonics by generating negative harmonics with switching angles calculated for selective harmonic elimination method. In order to confirm the proposed method, first Matlab/ Simulink and PSIM simulation results are given. Then the proposed method is also validated by experiments with Opal-RT controller and a 10 kW three phase, five-level DCMLI prototype.

KEYWORDS:

1.      Fundamental switching

2.      Harmonic elimination

3.      Multilevel inverter.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT  DIAGRAM:

EXPECTED SIMULATION RESULTS:

CONCLUSION:

The selected harmonic elimination is a popular issue in multilevel inverter design. The proposed selective harmonic elimination method for DCMLI has been validated in both simulation and experiment. The simulation and experimental results show that the proposed algorithm can be used to eliminate any number of specific lower order harmonics effectively and results in a dramatic decrease in the output voltage THD. In the proposed harmonic elimination method, the lower order harmonic distortion is largely reduced in fundamental switching. Furthermore, in the experiments reported here, an induction motor load is connected to the three-phase five-level DCMLI, and the current as well as the voltage waveforms are collected for analysis. The FFTs of these waveforms show that their harmonic content is close to the simulated values.

REFERENCES:

[1] J. Rodríguez, J. S. Lai, F. Z. Peng, “Multilevel inverters: a survey of topologies, controls, and applications,” IEEE Transactions on Industrial Electronics, vol.49, no.4, pp. 724-738, 2002.

[2] J. S. Lai, F. Z. Peng, “Multilevel converters-a new breed of power converters,” IEEE Transactions on Industry Applications, vol. 32, no.3, pp. 509-517, 1996.

[3] L. M. Tolbert, F. Z. Peng, T. G. Habetler, “Multilevel converters for large electric drives,” IEEE Transactions on Industry Applications, vol. 35, no. 1, pp. 36–44, Jan./Feb. 1999.

[4] S. Khomfoi, L. M. Tolbert, “Multilevel Power Converters,” Chapter 17, Power Electronics Handbook, 2nd Edition, Elsevier, ISBN 978-0- 12-088479-7, pp. 451-482, 2007.

[5] J. N. Chiasson, L. M. Tolbert, K. J. McKenzie, Z. Du, “A complete solution to the harmonic elimination problem,” IEEE Transactions on Power Electronics, vol. 19, no. 2, pp. 491-499, 2004.

Quasi Current Mode Control for the Phase-Shifted

Series Resonant Converter

ABSTRACT:

A novel indirect current mode control is applied in the phase-shifted series resonant converter system. The current is generated from resonant tank vector and the resonant current is regulated indirectly through quasi current mode control and thus the dynamic performance of the converter system is improved. Only single voltage feedback is required for the system. The proposed system consists of two control loops with one inner resonant vector and one outer voltage loop. Analysis and practical experiments are carried out and the results show the better performance compared with that of the conventional control.

KEYWORDS:

1.      Dynamic performance

2.      Dynamic response

3.      Phase shifted series resonant converter (PSRC)

4.       Quasi current mode control.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

BLOCK DIAGRAM:

EXPECTED SIMULATION RESULTS:

CONCLUSION:

The proposed control method based on the indirectly regulation of the resonant current is applied to the phase-shifted resonant converter. Only single voltage feedback is needed and it is converted to resonant tank vector components. Thus the output voltage is controlled more effectively and the dynamic performance is improved. Better performance has been verified through system analysis and experiments. In addition, the construction of the reformed control system is simple because only single voltage sensor is required. No current sensor is needed and the reformed control is monitored internally through quasi current vector.

REFERENCES:

[1] D. M. Sable and F. C. Lee, “The operation of a full bridge, zero voltage switched PWM converter,” in Proc. Virginia Power Electron. Ctr. Sem., 1989, pp. 92–97.

[2] A. J. Forsyth, P. D. Evans, M. R. D. Al-Mothafar, and K. W. E. Cheng, “A comparison of phase-shift controlled resonant and square-wave converters for high power ion engine control,” in Proc. Eur. Space Power Conf., 1991, pp. 179–185.

[3] H. L. Chan, K. W. E. Cheng, and D. Sutanto, “Phase-shift controlled DC-DC converter with bi-directional power flow,” Proc. Inst. Elect. Eng., vol. 148, no. 2, pp. 193–201, Mar. 2001.

[4] A. J. Forsyth, P. D. Evans, K. W. E. Cheng, and M. R. D. Al-Mothafar, “Operating limits of power converters for high power ion engine control,” in Proc. 22nd Int. Elect. Propul. Conf., 1991, [CD ROM].

[5] R. L. Steigerwald, “A comparison of half-bridge resonant converter topologies,” IEEE Trans. Power Electron., vol. PE-3, no. 2, pp. 174–182, Apr. 1988.