A Flexible Power Control for PV-Battery-HybridSystem Using Cascaded H-Bridge Converters

ABSTRACT:

The cascaded H-Bridge (CHB) is a good candidate to integrate multiple PV arrays into the power grid. However, due to the internal uncertain power supply of renewable sources, it is difficult to meet the power grid power command with only PV arrays. To overcome this limitation, a CHB converter with both PV arrays and energy storage units in the DC rails is proposed in this paper. Firstly, a two-layer hierarchical control is developed for independent PQ control and power distribution among each CHB cell, while meeting with the grid PQ reference command at the same time. Then, a modified power management method is developed to adaptively modify the current power points for PV panels from their maximum power points to solve the potential over-modulation problem caused by frequent battery charging and discharging. With the proposed approach, a good harvesting of PV power can be ensured in various situations. Verification results are provided to validate the performance of the proposed system.

 KEYWORDS:

  1. Cascaded H-bridge
  2. Power control
  3. Coordinated control
  4. PV-Battery system

 SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a compact single-phase PV-battery-hybrid system is developed with a single stage CHB converter, where both PV panels and battery are connected to separate DC rails of the converter. To achieve proper MPPT of each PV array and at the same time, avoid conflicts caused by the difference between PV output power and the grid power demand, a hierarchical control power control scheme is developed. The central controller is responsible for the regulation of grid current to meet the grid demand and the local controller of each H-bridge cell is responsible for MPPT of PV arrays. The battery in the proposed system acts as a buffer to compensate the gap between PV output power and grid demand. To overcome the potential over-modulation problems when the battery is absorbing power with reference voltage angle opposite to that of the PV cells, a modified power management method which can slightly changes PV array operation point in an online manner, is also developed. This method can be used to obtain the maximum allowable output power of PV while ensure an accurate control of power transfer to the grid mains. Since this paper only gave a roughly sketched control scheme of the CHB-based PV-battery-hybrid system, there are still some limitations at present. E.g., firstly, to fit the system PV power capacity, the capacity of the battery may be fairly large as well, thus it may exceed the limitation of system construction investment. However, it should be noted that even if the capacity of the battery is limited, it is still able for this CHB-based system to provide a schedulable output power and participate in the grid power flow regulation in an acceptable region, which will still be effective to improve the energy utilization in a limited range, and help reduce the PV discarding rate. The system planning issue was beyond this topic and not discussed in detail. Secondly, In general, distributed power cells are always required to be able to plug-and-play. While this series system is highly dependent on the communication system, the plug-and-play implementation issue should also consider the communication system design in each controller, making it not only a control issue but also a communication issue. The plug-and-play operation remains a rather interesting topic to be studied in our future work.

REFERENCES:

[1] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg. “A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules,” IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1292–1306, Sep./Oct. 2005.

[2] F. Blaabjerg, Y. Yang, D. Yang, X. Wang. “Distributed Power-Generation Systems and Protection,” Proc. IEEE, vol. 105, no. 7, pp. 1311–1331, July. 2017.

[3] S. V. Araújo, P. Zacharias, and R. Mallwitz, “Highly Efficient Single-Phase Transformerless Inverters for Grid-Connected Photovoltaic Systems,” IEEE Trans. Ind. Electron., vol. 57, no. 9, pp. 3118-3128, Sep. 2010.

[4] B. Yang, Wuhua Li, Y. Zhao, X. He. “Design and Analysis of a Grid-Connected Photovoltaic Power System,” IEEE Trans. Power Electron., vol. 25, no. 4, pp. 992-1000, Apr. 2010.

[5] J. He and Y. W. Li, “Analysis, design and implementation of virtual impedance for power electronics interfaced distributed generation,” IEEE Trans. on Ind. Appl., vol. 47, pp. 2525-2538, Nov/Dec. 2011.

Development of High-Performance Grid-Connected Wind Energy Conversion System for Optimum Utilization of Variable Speed Wind Turbines

ABSTRACT:

This paper presents an improvement technique for the power quality of the electrical part of a wind generation system with a self-excited induction generator (SEIG) which aims to optimize the utilization of wind power injected into weak grids. To realize this goal, an uncontrolled rectifier-digitally controlled inverter system is proposed. The advantage of the proposed system is its simplicity due to fewer controlled switches which leads to less control complexity. It also provides full control of active and reactive power injected into the grid using a voltage source inverter (VSI) as a dynamic volt ampere reactive (VAR) compensator. A voltage oriented control (VOC) scheme is presented in order to control the energy to be injected into the grid. In an attempt to minimize the harmonics in the inverter current and voltage and to avoid poor power quality of the wind energy conversion system (WECS), an filter is inserted between VOC VSI and the grid. The proposed technique is implemented by a digital signal processor (DSP TMS320F240) to verify the validity of the proposed model and show its practical superiority in renewable energy applications.

KEYWORDS:

  1. Grid connected systems
  2. Self-excited induction generator (SEIG)
  3. Voltage oriented control (VOC)
  4. Voltage source inverter (VSI)
  5. Wind energy conversion systems (WECSs)

 SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, the SEIG-based WECS dynamic model has been derived. The VOC grid connected VSI has been investigated for high performance control operation. The test results showed how the control scheme succeeded in injecting the wind power as active or reactive power in order to compensate the weak grid power state. An filter is inserted between VOC VSI and grid to obtain a clean voltage and current waveform with negligible harmonic content and improve the power quality. Also, this technique achieved unity power factor grid operation (average above 0.975), very fast transient response within a fraction of a second (0.4 s) under different possible conditions (wind speed variation and load variation), and high efficiency due to a reduced number of components (average above 90%) has been achieved. Besides the improvement in the converter efficiency, reduced mechanical and electrical stresses in the generator are expected, which improves the overall system performance. The experimental results obtained from a prototype rated at 250 W showed that the current and voltage THD (2.67%, 0.12%), respectively, for the proposed WECS with filter is less than 5% limit imposed by IEEE-519 standard. All results obtained confirm the effectiveness of the proposed system feasible for small-scale WECSs connected to weak grids.

REFERENCES:

[1] V. Kumar, R. R. Joshi, and R. C. Bansal, “Optimal control of matrix-converter-based WECS for performance enhancement and efficiency optimization,” IEEE Trans. Energy Convers., vol. 24, no. 1, pp. 264–272, Mar. 2009.

[2] Y. Zhou, P. Bauer, J. A. Ferreira, and J. Pierik, “Operation of grid connected DFIG under unbalanced grid voltage,” IEEE Trans. Energy Convers., vol. 24, no. 1, pp. 240–246, Mar. 2009.

[3] S. M. Dehghan, M.Mohamadian, and A. Y. Varjani, “A new variable speed wind energy conversion system using permanent-magnet synchronous generator and z-source inverter,” IEEE Trans Energy Convers., vol. 24, no. 3, pp. 714–724, Sep. 2009.

[4] K. Tan and S. Islam, “Optimum control strategies for grid-connected wind energy conversion system without mechanical sensors,” WSEAS Trans. Syst. Control, vol. 3, no. 7, pp. 644–653, Jul. 2008, 1991-8763.

[5] B. C. Rabelo, W. Hofmann, J. L. da Silva, R. G. de Oliveira, and S. R. Silva, “Reactive power control design in doubly fed induction generators for wind turbines,” IEEE Trans. Ind. Elect., vol. 56, no. 10, pp. 4154–4162, Oct. 2009.

An Efficient UPF Rectifier for a Stand-AloneWind Energy Conversion System

ABSTRACT:

In this paper, a near-unity-power-factor front-end rectifier employing two current control methods, namely, average current control and hysteresis current control, is considered. This rectifier is interfaced with a fixed-pitch wind turbine driving a permanent-magnet synchronous generator. A traditional diode-bridge rectifier without any current control is used to compare the performance with the proposed converter. Two constant wind speed conditions and a varying wind speed profile are used to study the performance of this converter for a rated stand-alone load. The parameters under study are the input power factor and total harmonic distortion of the input currents to the converter. The wind turbine generator–power electronic converter is modeled in PSIM, and the simulation results verify the efficacy of the system in delivering satisfactory performance for the conditions discussed. The efficacy of the control techniques is validated with a 1.5-kW laboratory prototype, and the experimental results are presented.

 KEYWORDS:

  1. Average current control (ACC)
  2. Hysteresis current control (HCC)
  3. Permanent-magnet synchronous generator (PMSG)
  4. Unity-power-factor (UPF) converter

 SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a WECS interfaced with a UPF converter feeding a stand-alone load has been investigated. The use of simple bidirectional switches in the three-phase converter results in near-UPF operation. Two current control methods, i.e., ACC and HCC, have been employed to perform active input line current shaping, and their performances have been compared for different wind speed conditions. The quality of the line currents at the input of the converter is good, and the harmonic distortions are within the prescribed limits according to the IEEE 519 standard for a stand-alone system. A high power factor is achieved at the input of the converter, and the voltage maintained at the dc bus link shows excellent voltage balance. The proposed method yields better performance compared to a traditional uncontrolled diode bridge rectifier system typically employed in wind systems as the front-end converter. Finally, a laboratory prototype of the UPF converter driving a stand-alone load has been developed, and the ACC and HCC current control methods have been tested for comparison. The HCC current control technique was found to be superior and  has better voltage balancing ability. It can thus be an excellent front-end converter in a WECS for stand-alone loads or grid connection.

REFERENCES:

[1] C. E. A. Silva, D. S. Oliveira, L. H. S. C. Barreto, and R. P. T. Bascope, “A novel three-phase rectifier with high power factor for wind energy conversion systems,” in Proc. COBEP, Bonito-Mato Grosso do Sul, Brazil, 2009, pp. 985–992.

[2] Online. Available: http://en.wikipedia.org/wiki/Wind_energy

[3] M. Druga, C. Nichita, G. Barakat, B. Dakyo, and E. Ceanga, “A peak power tracking wind system operating with a controlled load structure for stand-alone applications,” in Proc. 13th EPE, 2009, pp. 1–9.

[4] S. Kim, P. Enjeti, D. Rendusara, and I. J. Pitel, “A new method to improve THD and reduce harmonics generated by a three phase diode rectifier type utility interface,” in Conf. Rec. IEEE IAS Annu. Meeting, 1994, vol. 2, pp. 1071–1077.

[5] A. I. Maswood and L. Fangrui, “A novel unity power factor input stage for AC drive application,” IEEE Trans. Power Electron., vol. 20, no. 4, pp. 839–846, Jul. 2005.

A Novel Control Strategy for a Variable Speed Wind Turbine with a Permanent Magnet Synchronous Generator

ABSTRACT:

This paper presents a novel control strategy for the operation of a direct drive permanent magnet synchronous generator (PMSG) based stand alone variable speed wind turbine. The control strategy for the generator side converter with maximum power extraction is discussed. The stand alone control is featured with output voltage and frequency controller capable of handling variable load. The potential excess of power is dissipated in the damp resistor with the chopper control and the dc link voltage is maintained. Dynamic representation of dc bus and small signal analysis are presented. Simulation results show that the controllers can extract maximum power and regulate the voltage and frequency under varying wind and load conditions. The controller shows very good dynamic and steady state performance.

KEYWORDS:

  1. Permanent magnet synchronous generator
  2. Maximum power extraction
  3. Switch-mode rectifier
  4. Variable speed
  5. Wind turbine
  6. Voltage and frequency control

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

Control strategy for a direct drive stand alone variable speed wind turbine with a PMSG is presented in this paper. A simple control strategy for the generator side converter to extract maximum power is discussed and implemented using Simpower dynamic system simulation software. The controller is capable to maximize output of the variable speed wind turbine under fluctuating wind. The load side PWM inverter is controlled using vector control scheme to maintain the amplitude and frequency of the inverter 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:

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

[2] Polinder H., Van der Pijl F. F. A, de Vilder G. J., Tavner P. J.:  “Comparison of direct-drive and geared generator concepts for wind turbines,” IEEE Trans. on energy conversion, 2006, . 21, (3), pp. 725- 733.

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

[4] De Broe M., Drouilhet S., and Gevorgian V.: “A peak power tracker for small wind turbines in battery charging applications,” IEEE Trans. Energy Convers. 1999, 14, (4), pp. 1630–1635.

[5] Datta R., and Ranganathan V. T.: “A method of tracking the peak power points for a variable speed wind energy conversion system,” IEEE Trans. Energy Convers., 1999, 18, (1), pp. 163–168.

A Single-Phase Buck Matrix Converter with High-Frequency Transformer Isolation and Reduced Switch Count

ABSTRACT:

In this paper, a new type of matrix converter also called a single-phase high-frequency transformer  isolated (HFTI) buck matrix converter (MC) is proposed. The proposed converter can provide step-down operation of the input voltage with various types of output voltages such as; in-phase and out-of-phase output voltages, rectified (or positive) output voltage, and output voltage with step-changed frequency. By incorporating HFT isolation, the proposed MC saves an extra bulky line frequency transformer, which is required for the conventional MCs to provide electrical isolation and safety, when used in application such as dynamic voltage restorers (DVRs), etc. Two different circuit variations of the proposed HFTI MC are presented with and without  continuous output currents, with the latter having less passive components. The safe-commutation strategy is also employed for the proposed HFTI MC to provide current path for the inductor during dead-time, which avoids switch voltage spikes without adding any snubber circuits. The operation principle and circuit analysis of the  proposed MC are presented, and switching strategies are also developed to obtain various output voltages. Moreover, a prototype of the proposed MC is fabricated, and experiments are performed to produce in-phase/out-of-phase and rectified output voltages, and output voltage with step-changed frequency.

KEYWORDS:

  1. High-frequency transformer
  2. In-phase and out-of-phase operations
  3. Rectified output
  4. Single-phase matrix converter
  5. Step-changed frequency

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

In this paper, a buck MC is proposed with HFT isolation. The proposed MC is capable of providing various types of output voltages, such as in-phase, out-of-phase and rectified output voltages. Moreover, the frequency of the output voltage can be changed in steps, so that it is integer multiple or integer fraction of the input voltage frequency. The use of HFT isolation in the proposed MC for electrical isolation and safety benefits in that it removes the need for extra bulky line frequency transformer, which is added with conventional non-isolated MCs for applications as DVRs.

Two different secondary side structures of the proposed HFTI buck MC are proposed, with one having continuous output current, and the other having discontinuous out current but with one inductor and capacitor less. The soft-commutation strategy is suggested for the proposed MC, which avoids switch voltage spikes without using any snubber circuits. The operation principle and circuit analysis of the proposed converter are presented and switching strategies are also developed to obtain various output voltages. Moreover, a 200 W laboratory prototype of the proposed MC is fabricated, and experiments are performed to produce in-phase/out-of-phase and rectified output voltages, and output voltage with step-changed frequency.

REFERENCES:

[1] F. Z. Peng, L. Chen, and F. Zhang, “Simple topologies of PWM ac-ac converters,” IEEE Power Electron. Letters, vol. 1, no. 1, pp. 10– 13, Mar. 2003.

[2] T. B. Lazzarin, R. L. Andersen, and I. Barbi, “A switched-capacitor three-phase ac-ac converter,” IEEE Trans. Ind. Electron., vol. 62, no. 2, pp. 735–745, Feb. 2015.

[3] H. F. Ahmed, H. Cha, A. A. Khan, and H.-G. Kim, “A family of high-frequency isolated single-phase Z-source ac-ac converters with safe-commutation strategy,” IEEE Trans. Power Electron., vol. 31, no. 11, pp. 7522–7533, Nov. 2016.

[4] C. Liu, B. Wu, N. R. Zargari, D. Xu and J. Wang, “A novel three-phase three-leg ac-ac converter using nine IGBTs,” IEEE Trans. Power Electron., vol. 24, no. 5, pp. 1151–1160, May. 2009.

[5] C. B. Jacobina, I. S. d. Freitas, E. R. C. d. Silva, A. M. N. Lima, and R. L. d. A. Riberio, “Reduced switch count dc-link ac-ac five-leg converter,” IEEE Trans. Power Electron., vol. 21, no. 5, pp. 1301–1310, Sep. 2006.

 

Modeling, Simulation and Implementation of aFive-Phase Induction Motor Drive System

ABSTRACT:

This paper presents a comprehensive simulation model of a five-phase induction motor drive system. Both open loop and closed-loop control is elaborated. The complete component modeling is developed using ‘simpower system’ blocksets of Matlab/Simulink. To address the real time implementation issues, dead banding of the inverter switches are also incorporated in the simulation model. To validate the modeling procedure, experimental implementation is done in TMS320F2812 DSP platform with a custom built five-phase drive system. Excitation, acceleration and loading transients are investigated. The developed simulation model is fully verified by the real time implementation.

 KEYWORDS:

  1. Five-phase drive
  2. V/f control
  3. Induction motor

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

This paper presents a complete simulation model to simulate a five-phase induction motor drive system for constant v/f speed control method. The simulation model is developed using simpower system block sets of the Matlab/Simulink software. Step by step model development is elaborated. Dead banding in the simulation procedure is presented. A detailed simulation results are presented to validate the modeling procedure. Experimental set up is discussed and the experimental results are provided to exactly match the results obtained using simulation. This proves the successful implementation of the control scheme.

REFERENCES:

[1] D. Novotony, and T.A. Lipo, Vector control and dynamics of ac drives, Clarendon Press, Oxford, UK, 2000.

[2] A.M. Trzynadlowski, The field oriented Principle in Control of Induction motors, Kuluwer Press, 1994.

[3] I. Boldea and S.A. Nasar, Vector Control of AC Drives, CRC Press, London, 1992.

[4] D.C. White and H.H. Woodson, Electromechanical energy conversion, John Wiley and Sons, New York, 1959.

[5] S.A. Nasar and I. Boldea, The Induction Machine Handbook, CRC Press, London, 2002.

Power Quality Analysis and Enhancement ofGrid Connected Solar Energy System

ABSTRACT:

In recent years, renewable energy resources are utilized to meet the growing energy demand. The  integration of renewable energy resources with the grid incorporates power electronic converters for conversion of energy. These power electronic converters introduce power quality issues such as a harmonics, voltage regulation etc. Hence, to improve the power quality issues, this work proposes a new control strategy for a grid interconnected solar system. In this proposed work, a maximum power point tracking (MPPT) scheme has been used to obtain maximum power from the solar system and DC/DC converter is implemented to maintain a constant DC voltage. An active filtering method is utilized to improve the power quality of the grid connected solar system. The proposed system is validated through dynamic simulation using MATLAB/Simulink Power system toolbox and results are delivered to validate the effectiveness of the work.

KEYWORDS:

  1. Power Quality
  2. Active Power Filter
  3. Fuzzy Controller
  4. Harmonics Compensation

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This work has presented a novel control of an existing grid interfacing inverter to improve the quality of power at PCC. It has been proved that the grid-interfacing inverter can be effectively utilized for power conditioning without affecting its normal operation of real power transfer. This approach eliminates the need for additional power conditioning equipment to improve the quality of power. Extensive MATLAB/Simulink simulation results have validated the proposed approach and have shown that the grid-interfacing inverter can be utilized as a multi-function device.

REFERENCES:

[1] Akagi, H. (2006) Modern Active Filters and Traditional Passive Filters. Bulletin of the Polish Academy of Sciences Technical Sciences, 54, 255-269.

[2] Kazem, H.A. (2013) Harmonic Mitigation Techniques Applied to Power Distribution Networks. Advances in Power Electronics. http://dx.doi.org/10.1155/2013/591680

[3] Ravindra, S., Veera Reddy, V.C., Sivanagaraju, S. and Gireesh Kumar, D. (2012) Design of Shunt Active Power Filter to Eliminate the Harmonic Currents and to Compensate the Reactive Power under Distorted and or Imbalanced Source Voltages in Steady State. International Journal of Engineering Trends and Technology, 3, 1-6.

[4] Kumar, A. and Singh, J. (2013 Harmonic Mitigation and Power Quality Improvement Using Shunt Active Power Filter. International Journal of Electrical, Electronics and Mechanical Control, 2, 13 p.

[5] Gligor, A. (2009) Design and Simulation of a Shunt Active Filter in Application for Control of Harmonic Levels. Acta Universitatis Sapientiae, Electrical and Mechanical Engineering, 53-63.

 

Modified Cascaded H-bridge Multilevel Inverter for Hybrid Renewable Energy Applications

ABSTRACT:

Renewable energy sources and technologies have the potential to provide solutions to the longstanding energy problems being faced by developing countries. The renewable energy sources like wind energy, solar energy, geothermal energy, ocean energy, biomass energy and fuel cell technology can be used to overcome energy shortage in India. This paper proposes a modified multi-level inverter (MLI) topology for Hybrid Renewable Energy Sources (HRES) and a design of hybrid solar-wind power generation model with 9-level, 13-level and 17-level inverter topologies. A HRES connected to a modified Cascaded H-Bridge Multi Level Inverter (CHB-MLI) is developed, whose switches are controlled using Artificial Neural Network (ANN) model. The proposed hybrid energy system model consists of 10 Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) that intend to give 17 levels of output voltage. The proposed topology performs effectively with reduced number of components and reduced Total Harmonic Distortion (THD). The performance of the proposed system is analyzed by designing the model in MATLAB/SIMULINK environment. The simulation results of the proposed inverter for the HRES application are compared with the results of the existing topologies to show the effectiveness of the proposed model.

 KEYWORDS:

  1. Battery energy storage system (BESS)
  2. Modified cascaded H-bridge Multi-level inverter (MCHBMLI)
  3. Total harmonic distortion (THD)

 SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, 9-level, 13-level and 17-level inverters are designed by employing modified cascaded MLI, followed by ANN as a control approach for the inverter. Using the ANN method, the MPP exactly searching when the solar irradiance changes sharply, and it can make the system work under a stable mode. The advantage of the ANN-based PV model method is the fast MPP approximation according to the parameters of the PV panel. The proposed new MPPT algorithm can search the MPP fast and exactly based on the feedback voltage and current with different solar irradiance and temperature of the environment. The simulations are performed in MATLAB/SIMULINK environment. The output voltage waveform shows less distortion with a reduced number of power switches and is validated by calculating THD as a performance measure. The results attained from the proposed model exhibits superiority over the previously suggested models when compared. The proposed modified system can be analyzed in the future, with different sources such as fuel cell, diesel generator, etc. in the standalone microgrid topology. This is more cost-effective due to the use of reduced number of switches and other components. Thus it helps in improving the total harmonic distortions as per the IEEE 519 standards, in terms of power quality of the islanded microgrid. The limitation of the proposed topology is that, in case of a failure of one ofH-bridges, theMLI can still be operated with decreased number of levels. However, full power cannot be supplied to the load. This can be improved by designing a fault tolerant MLI topology in the future.

REFERENCES:

  1. M. A. Rosen, and I. Dincer, “Exergy as the confluence of energy, environment and sustainable development,” Exergy Int. J., Vol. 1, pp. 3–13, 2001.
  2. P. Thongprasri. “Capacitor voltage balancing in the dc-link five-level full-bridge diode-clamped multilevel inverter,” 2016.
  3. C. L. Kuppuswamy, and T. A. Raghavendiran. “FPGA Implementation of Carrier Disposition PWM for Closed Loop Seven Level Diode Clamped Multilevel Inverter in Speed Control of Induction Motor,” 2018.
  4. F. Khoucha, S. M. Lagoun, K. Marouani, A. Kheloui, and M. El Hachemi Benbouzid, “Hybrid cascaded H-bridge multilevel-inverter induction-motor-drive direct torque control for automotive applications,” IEEE Trans. Ind. Electron., Vol. 57, no. 3, pp. 892–899, 2010.
  5. V. Jammala, S. Yellasiri, and A. K. Panda, “Development of a new hybrid multilevel inverter using modified carrier SPWM switching strategy,” IEEE Trans. Power Electron., Vol. 33, no. 10, pp. 8192–8197, 2018.

Model Predictive Control for Shunt Active Filters With Fixed Switching Frequency

ABSTRACT:

This paper presents a modification to the classical Model Predictive Control algorithm, named Modulated Model Predictive Control, and its application to active power filters. The proposed control is able to retain all the advantages of a Finite Control Set Model Predictive Control whilst improving the generated waveforms harmonic spectrum. In fact a modulation algorithm, based on the cost function ratio for different output vectors, is inherently included in the MPC. The cost function based modulator is introduced and its effectiveness on reducing the current ripple is demonstrated. The presented solution provides an effective and straightforward single loop controller, maintaining an excellent dynamic performance despite the modulated output and it is self-synchronizing with the grid. This promising method is applied to the control of a Shunt Active Filter for harmonic content reduction through a reactive power compensation methodology. Significant results obtained by experimental testing are reported and commented, showing that MPC is a viable control solution for active filtering systems.

KEYWORDS:

  1. Smart Grids
  2. Power Quality
  3. Active Filters
  4. Power Filters
  5. Harmonic Distortion
  6. Model Predictive Control

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

Power quality regulation is a relevant topic in modern electrical networks. Improving the quality of the delivered energy is an important characteristic in the new smart grids where there is an increasing demand of dynamic, efficient and reliable distribution systems. The use of active filters becomes therefore vital for the reduction of harmonic distortions in the power grid. This paper has presented the development and the implementation of a SAF for harmonic distortion reduction regulated by an improved Modulated Model Predictive Controller.

Based on the system model, it dynamically predicts the values of all the variable of interest in order to obtain a multiple control target optimization by minimizing a user defined cost function. Moreover the higher current ripple typical of MPC has been considerably reduced by introducing a cost function based modulation strategy without compromising the dynamic performances. A SAF prototype implementing the proposed solution was then described, finally reporting and commenting the promising experimental tests results both in transient conditions and steady-state. It was hence demonstrated that FCS-M2PC is a viable and effective solution for control of active power compensators, where different systems variables can be regulated with the aid of only a single control loop, with no need for grid synchronization devices.

REFERENCES:

[1] P. Salmeron and S. P. Litran, “Improvement of the Electric Power Quality Using Series Active and Shunt Passive Filters,” IEEE Trans. Power Del., vol. 25, no. 2, pp. 1058–1067, 2010.

[2] H. Johal and D. Divan, “Design Considerations for Series-Connected Distributed FACTS Converters,” IEEE Trans. Ind. Appl., vol. 43, no. 6, pp. 1609–1618, 2007.

[3] D. Divan and H. Johal, “Distributed FACTS—A New Concept for Realizing Grid Power Flow Control,” IEEE Trans. Power Electron., vol. 22, no. 6, p. 2253, 2007.

[4] 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, 1999.

[5] M. L. Heldwein, H. Ertl, J. Biela, D. Das, R. P. Kandula, J. A. Munoz, D. Divan, R. G. Harley, and J. E. Schatz, “An Integrated Controllable Network Transformer—Hybrid Active Filter System,” IEEE Trans. Ind. Appl., vol. 51, no. 2, pp. 1692–1701, 2015.

A Modified Cascaded H-Bridge Multilevel Inverter For Solar Applications

ABSTRACT:

In this paper, a modified cascaded H-bridge multilevel inverter (MLI) is proposed and designed for solar applications. Generally, as the level of conventional multilevel inverter increases, the required number of switches and size increases. The proposed topology is cascade of unit stages which involves 5 switches and two voltage source; moreover a unit stage is capable of generating 5 levels. Also, the detailed analysis of cascaded multilevel inverter is discussed which incorporates three different methodologies involving less number of power devices in order to generate maximum number of levels. This results into reduction in gate drive circuitry and less switching losses. The proposed MLI is designed for power 1.5kW and Inphase level shifting SPWM technique has been incorporated in which 5kHz carrier wave is compared with 50Hz of sinusoidal wave with a modulation index of 0.8. As a result, total harmonic distortion (THD) is achieved as 4.71% with LC-filter for above mentioned multilevel inverter. The circuits are modeled and simulated with the help of MATLAB/SIMULINK.

KEYWORDS:

  1. Modified cascaded H-bridge MLI
  2. Solar
  3. SPWM techniques
  4. Total Harmonic Distortions

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

In this paper, a new topology of modified cascaded H bridge MLI is designed for solar high power application. The three different methodologies have been analyzed and 9-level, 13-level and 17-level output is observed in the respective methodology. The number of switches used in the topology is less which in turn reduced the corresponding gate driving circuitry and made the circuit compact in size. The circuits of proposed MLI are simulated in MATLAB/SIMULINK and total harmonic distortions for the three methodologies are obtained by using FFT analysis window. The lowest THD observed with LC-filter is 4.71%. The proposed MLI is designed for power 1.5kW and In-Phase level shifting method is followed for the pulse generation for all three methodologies.

REFERENCES:

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