A New Circuit of Modular Multilevel Inverter for Grid-Connected Photovoltaic Conversion Plants

ABSTRACT:

This study presents a new circuit topology of the Modular Multilevel Converter (MMC) which is deployed for photovoltaic grid applications. In the conventional MMC, two arm inductors are placed in each phase to limit the circulating current. In the proposed topology, the inductors are replaced by a transformer. The proposed circuit gives a 50% reduction of the voltage rating of the power devices and the capacitors in comparison with the conventional MMC. The required dc-link voltage which is fed directly by PV panels is also reduced by half. The paper presents a PWM method to control the solar inverter output voltage. The proposed concept is confirmed through simulation and experimental results.

KEYWORDS:

1.      Photovoltaic (PV) conversion

2.      Modular multilevel converter

3.      Pulse width modulation

4.      Parameter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, the feasibility of a new circuit topology for the MMC has been outlined, where it is deployed as an interface between the grid and PV modules. With this arrangement, the voltage rating of capacitors and the power semiconductor devices are effectively reduced by half. The dc bus magnitude which is formed by the dc output from PV array is also reduced by half. A method to suppress the 2nd harmonic current in the inverter has been discussed. The concept of level-shifted PWM, where the modulating waveform is shifted and scaled to bring inside one carrier, has been used to reduce the switching frequency. With this, there is no need to calculate the duty cycle of individual cells. The proposed idea has been verified by simulation and experimental results under disturbance in the system caused by solar irradiance changes.

REFERENCES:

[1] Q.-C. Zhong and T. Hornik, Control of Power Inverters in Renewable Energy and Smart Grid Integration, Hoboken, NJ: Wiley, 2013.

[2] A. G. Golnas, “PV system reliability: An operator’s perspective,” IEEE J. Photovolt., Vol. 3, No. 1, pp. 416-421, Jan. 2013.

[3] International Energy Agency. (2010, May). Technology Roadmap, Solar Photovoltaic Energy [Online].

[4] E. Romero-Cadaval, G. Spagnuolo, L. G. Franquelo, et al., “Grid-Connected Photovoltaic Generation Plants,” IEEE Ind. Electron. Mag., Vol. 7, No. 3, pp. 6-20, Sept. 2013.

[5] M. G. Villalva, J. R. Gazoli and E. R. Filho, “Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays,” IEEE Trans. Power Electron, Vol. 24, No. 5, pp. 1198-1208, May 2009.

Selective Harmonics Elimination Technique in Single Phase Unipolar H-Bridge Inverter

ABSTRACT:  

Specific odd harmonics can be mitigated by operating the semiconductor switches in H-bridge inverters at optimized switching angles of the PWM signals. These switching angles can be achieved by deriving a number of nonlinear equations using Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) method. Modulation index (m) is a significant parameter used to control the amplitude of the fundamental output voltage of DC-AC inverter. By changing the value of modulation index the Total Harmonics Distortion (THD) also will change. In this paper, the performance of single phase full-bridge inverter using SHE-PWM scheme with varying the modulation index is evaluated. In order to achieve a minimum THD, a different number of nonlinear equations are used to calculate the switching angles. The performance of a single phase unipolar inverter is simulated in Matlab.

KEYWORDS:

1.      Selective Harmonic Elimination

2.      H-bridge Inverter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

Matlab-Simulink is used to evaluate the proposed technique in order to mitigate 3th, 5th, 7th, 9th, 11th & 13^th harmonics and to verify the influence of various condition of modulation index on THD in single-phase full-bridge H inverter. Low order odd harmonics can be mitigated successfully by using SHE-PWM also, by adjusting the switching angles the Total Harmonic Distortion is decreased to a minimum of 57.47%. These switching angles are applied to generate control signals of full-bridge H-inverter. By increasing the modulation index the THD decreased. Also, the fundamental voltage of the inverter is maximized by variation of modulation index with switching angles optimized.

REFERENCES:

[1]. Ashok, B., & Rajendran, A. (2013). Selective Harmonic Elimination of Multilevel Inverter Using SHEPWM Technique. International Journal of Soft Computing and Engineering (IJSCE), 3(2), 79–82.

[2]. Basri, A. B., Zaidi, N. A., Bopi, N. B., Aboadla, E. H., Khan, S., & Habaebi, M. H. (2016). EFFECTS OF SWITCHING FREQUENCY TO SERIES LOADED SERIES RESONANT CIRCUIT. ARPN Journal of Engineering and Applied Sciences, 11(1), 382–386.

[3]. Dahidah, M. S. A., & Agelidis, V. G. (2007). Non-symmetrical selective harmonic elimination PWM techniques: The unipolar waveform. PESC Record - IEEE Annual Power Electronics Specialists Conference, 1885–1891.

[4]. Edpuganti, K. (2015). Fundamental Switching Frequency Optimal Pulse width Modulation of Medium-Voltage Nine-Level Inverter. IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, 62(7), 4096– 4104.

[5]. Ghalib, M. A., & Abdalla, Y. S. (2014). Design and Implementation of a Pure Sine Wave Single Phase Inverter for Photovoltaic Applications. AMERRICAN SOCIETY FOR ENGINEERING EDUCATION, ASEE, 1– 8.

Selective Harmonic Elimination (SHE) for 3-Phase Voltage Source Inverter (VSI)

 ABSTRACT:

 The Selective Harmonic Elimination (SHE) for 3-Phase Voltage Source Inverter (VSI) is presented here. The projected work investigates the Selective Harmonic Elimination (SHE) to eliminate harmonics produced by Pulse Width Modulation (PWM) inverter. The selective harmonic elimination method for three phase Voltage Source Inverter (VSI) is generally based on ideas of opposite harmonic injection. In this proposed scheme, the lower order harmonics (3rd, 5th, 7th, and 9th) are eliminated by the dominant harmonics of same order generated in opposite phase by Sinusoidal Pulse Width Modulation (SPWM) inverter and by using this scheme the Total Harmonic Distortion (THD) is reduced. Analysis of Sinusoidal Pulse Width Modulation (SPWM) technique and Selective Harmonic Elimination (SHE) is simulated using MATLAB/SIMULINK model.

KEYWORDS:

1.      Selective Harmonic Elimination (SHE)

2.      Pulse Width Modulation (PWM) e

3.      Total Harmonic Distortion (THD) and Voltage Source Inverter (VSI)

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

The paper presents a selective harmonic elimination technique for three phase voltage source inverter with the RL load. A Three phase Voltage Source Inverter (VSI) changes DC input voltage to a three phase variable frequency variable voltage output. The elimination of specific low-order harmonics from a given voltage/current waveform achieved by Selective Harmonic Elimination (SHE) technique. We unite the inductor filter with the capacitor the ripple aspect will turn out to be more or less autonomous of the load filter. Finally Analysis and comparison of Total Harmonic Distortion (THD) for sinusoidal Pulse Width Modulation (PWM) technique and selective harmonic elimination technique has been done. From the comparison it is very apparent that the Total Harmonic Distortion (THD) for selective harmonic technique is less than that of sinusoidal Pulse Width Modulation (PWM) method.

REFERENCES:

[1] Ray, R.N., Chatterjee, and Goswami, S.K, “Reduction of voltage harmonic using optimization – based combined approach on” proceeding on IET Power Electronics, 3 (3). 334-344. 2008.

[2] Mohamed S.A.Dahidah and Vassilios G. Agelidis, “Selective harmonic elimination PWM control for Cascaded multilevel voltage source converters: A generalized formula” IEEE Trans on power electronics, 23(4). 1620-1630. Jul. 2008.

[3] Wells, Jason R. Xin Geng, Chapman, Patrick L. and Krein, Philip T. “Modulation based harmonic elimination” IEEE Transactions on Power Electronics, 22(1). 2007.

[4] Fellow, Javier Napoles, Jose Ignacio Leon, and Aguirre, Miguel A. “A flexible selective harmonic mitigation to meet grid codes in three level PWM converters” IEEE Transactions on Industrial Electronics, 54(6).Dec.2007.

[5] Hadji, S. Touhami O. and C.J.Goodman, “Vector- optimized harmonic elimination for single- phase pulse width modulation inverters/converters” IET Electr.Power Appl.,1(3). 423-432. 2007

Nine Level Symmetrical Modified Multi-Level Cascaded H-Bridge Inverter

 ABSTRACT:

In this paper, a 9-level symmetrical modified multi-level cascaded H-bridge inverter with reduced switch count is considered. The operation and control of 9-level inverter is discussed. This multilevel inverter uses four symmetrical DC input sources and twelve unidirectional power

semiconductor switches. The basic operation with equal width modulation and resistive and Resistive-Inductive loads are verified with the help MATLAB simulation. The simulation outputs are presented and confirm the operation of nine level inverter operations. Together with the traditional topologies and some other inverters, this inverter topology is capable to produce more number of output voltage levels by means of less number of power switches and driver circuits. Simulation results confirm the probability of this inverter topology

KEYWORDS:

1.      Multi-Level inverter

2.      Cascaded H-Bridge (CHB)

3.      Reduced number of switches

4.      Harmonics

5.      Modified H-bridge (MHB)

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a modified CHB 9-level symmetrical MLI with 4 DC voltage sources and 12 unidirectional switches was successfully studied with the help of MATLAB simulation. The operation of this topology of inverter is analyzed. The simulation results are at satisfactory level.

The harmonics in the output voltages are comparable with the other topologies in the literature. This topology of inverter required less number of switches could assure enhanced performance, efficiency, consistency and decrease in price and volume of the inverter. The performance of this inverter topology can be improved by employing harmonic elimination techniques.

REFERENCES:

 1. Nabae. A, Takahashi. I, and Akagi. H, “A New Neutral-point-clamped PWM inverter,” IEEE Transactions on Industry Applications, Vol. IA-17, pp. 518-523, 1981.

2. Lai. J.S, and Peng. F.z, “Multilevel Converters: A New Breed of Power Converters,” IEEE Transactions on Industry Applications, Vol. 32, pp. 509-517, 1996.

3. Hammond. P.W, “A New Approach to Enhance Power Quality for Medium Voltage AC Drives,” IEEE Transactions on Industry Applications, Vol. 33, pp. 202-208, 1997.

4. C.Ganavel, M. Rajavelan, P. Muthukumar, T. Baldwin Immanuel, “A performance Investigation of a Single Phase Multilevel Inverter Fed Nonlinear loads for Solar PV Applications,” International Journal of Engineering & Technology, Vol. 7, pp. 388-391, 2018.

5. V Kartikeyan, V Jamuna, “Hybrid control strategy for BCD topology based modular multilevel inverter,” Circuits and Systems, Vol.7, pp. 1441-1454, 2016.

A Modified Seven Level Cascaded H Bridge Inverter

ABSTRACT:

Presently Multilevel inverters are extensively used for high-voltage applications and their execution is exceptionally better to that of regular two-level inverters due to minimized harmonic distortion, lower electromagnetic interference and larger DC link voltages. Nevertheless certain shortcomings are faced such as adding in number of components and voltage balancing problem. In order to overcome these, a seven-level hybrid inverter has been proposed. This topology requires a lesser number of power switches which results in the decrease of multifaceted nature, add up to cost and weight of the inverter. Finally this can be able to generate near sinusoidal voltages and approximately fundamental frequency switching. The simulation and the experimental results of a modified cascaded seven level H bridge inverter with and without LC filter are presented for validation.

KEYWORDS:

1.      Cascaded H-bridge inverter (CHBI)

2.      Seven level hybrid inverter

3.      Asymmetrical DC sources

4.      Total harmonic distortion (THD)

5.      Pulse Width modulation (PWM)

6.      Multi-level Inverter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

A modified cascaded seven level H-bridge inverter was fabricated which has the benefit of reduced THD, portability, and cost has compared to normal cascaded H-bridge inverter. Since the topology requires minimum switches, and low-cost real time interfacing device (Arduino) compared DSP, DSPACE, FPGA, etc., the overall expenditure for fabrication reduces. This paper envisages the working of proposed structure. An LC filter is introduced which helps in getting nearer to sinusoidal waveform. The concepts which are projected are verified through simulation and experimental results.

REFERENCES:

[1] E. Babaei and S.Hosseini, “Charge balance control methods for asymmetrical cascade multilevel converters”. In Proc. ICEMS, Seoul, Korea, 2007, pp, 74-79.

[2] K. Wang, Y. Li, Z. Zheng, and L. Xu, “Voltage balancing and fluctuation suppression methods of floating capacitors in a new modular multilevel converter,” IEEE Trans. Ind. Electron., vol. 60, no. 5, pp. 1943–1954,May 2013

[3] J. Napoles, A. J. Watson, and J. J. Padilla, “Selective harmonic mitigation technique for cascaded H-bridge converter with nonequal dc link voltages,” IEEE Trans. Ind. Electron., vol. 60, no. 5, pp. 1963–1971, May 2013.

[4] N. Farokhnia, S. H. Fathi, N. Yousefpoor, and M. K. Bakhshizadeh, “Minimisation of total harmonic distortion in a cascaded multilevel inverter by regulating of voltages dc sources,” IET Power Electron., vol. 5, no. 1, pp. 106–114, Jan. 2012.

[5] S. Mekhilef, M. N. Abdul Kadir, and Z. Salam, “Digital control of three phase three-stage hybrid multilevel inverter,” IEEE Trans. Ind. Informat., vol. 9, no. 2, pp. 719–727, May 2013.

Design and Performance Analysis of Three-Phase Solar PV Integrated UPQC

 ABSTRACT:

In this paper, the design and performance of a three phase solar PV (photovoltaic) integrated UPQC (PV-UPQC) are presented. The proposed system combines both the benefits of distributed generation and active power filtering. The shunt compensator of the PV-UPQC compensates for the load current harmonics and reactive power. The shunt compensator is also extracting maximum power from solar PV array by operating it at its maximum power point (MPP). The series compensator compensates for the grid side power quality problems such as grid voltage sags/swells by injecting appropriate voltage in phase with the grid voltage. The dynamic performance of the proposed system is simulated in Matlab-Simulink under a nonlinear load consisting of a bridge rectifier with voltage-fed load.

 KEYWORDS:

1.      Power Quality

2.      DSTATCOM

3.       DVR

4.       UPQC

5.      Solar PV

6.      MPPT

 SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The dynamic performance of three-phase PV-UPQC has been analyzed under conditions of variable irradiation and grid voltage sags/swells. It is observed that PV-UPQC mitigates the harmonics caused by nonlinear and maintains the THD of grid voltage, load voltage and grid current under limits of IEEE-519 standard. The system is found to be stable under variation of irradiation from 1000𝑊/𝑚2 to 600𝑊/𝑚2. It can be seen that PV-UPQC is a good solution for modern distribution system by integrating distributed generation with power quality improvement.

 REFERENCES:

[1] Y. Yang, P. Enjeti, F. Blaabjerg, and H. Wang, “Wide-scale adoption of photovoltaic energy: Grid code modifications are explored in the distribution grid,” IEEE Ind. Appl. Mag., vol. 21, no. 5, pp. 21–31, Sept 2015.

[2] B. Singh, A. Chandra and K. A. Haddad, Power Quality: Problems and Mitigation Techniques. London: Wiley, 2015.

[3] M. Bollen and I. Guo, Signal Processing of Power Quality Disturbances. Hoboken: Johm Wiley, 2006.

[4] P. Jayaprakash, B. Singh, D. Kothari, A. Chandra, and K. Al-Haddad, “Control of reduced-rating dynamic voltage restorer with a battery energy storage system,” IEEE Trans. Ind. Appl., vol. 50, no. 2, pp. 1295– 1303, March 2014.

[5] M. Badoni, A. Singh, and B. Singh, “Variable forgetting factor recursive least square control algorithm for DSTATCOM,” IEEE Trans. Power Del., vol. 30, no. 5, pp. 2353–2361, Oct 2015.

Design and Performance Analysis of Three-PhaseSolar PV Integrated UPQC

ABSTRACT:

This paper deals with the design and performance analysis of a three-phase single stage solar photovoltaic integrated unified power quality conditioner (PV-UPQC). The PV-UPQC consists of a shunt and series connected voltage compensators connected back to back with common DC-link.The shunt compensator performs the dual function of extracting power from PV array apart from compensating for load current harmonics. An improved synchronous reference frame control based on moving average filter is used for extraction of load active current component for improved performance of the PVUPQC. The series compensator compensates for the grid side power quality problems such as grid voltage sags/swells. The compensator injects voltage in-phase/out of phase with point of common coupling (PCC) voltage during sag and swell conditions respectively. The proposed system combines both the benefits of clean energy generation along with improving power quality. The steady state and dynamic performance of the system are evaluated by simulating in Matlab-Simulink under a nonlinear load. The system performance is then verified using a scaled down laboratory prototype under a number of disturbances such as load unbalancing, PCC voltage sags/swells and irradiation variation.

KEYWORDS:

1.      Power Quality

2.      Shunt compensator

3.      Series compensator

4.      UPQC

5.      Solar PV

6.      MPPT

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The design and dynamic performance of three-phase PVUPQC have been analyzed under conditions of variable irradiation and grid voltage sags/swells. The performance of the system has been validated through experimentation on scaled down laboratory prototype. It is observed that PVUPQC mitigates the harmonics caused by nonlinear load and maintains the THD of grid current under limits of IEEE-519 standard. The system is found to be stable under variation of irradiation, voltage sags/swell and load unbalance. The performance of d-q control particularly in load unbalanced condition has been improved through the use of moving average filter. It can be seen that PV-UPQC is a good solution for modern distribution system by integrating distributed generation with power quality improvement.

REFERENCES:

[1] B. Mountain and P. Szuster, “Solar, solar everywhere: Opportunities and challenges for australia’s rooftop pv systems,” IEEE Power and Energy Magazine, vol. 13, no. 4, pp. 53–60, July 2015.

[2] A. R. Malekpour, A. Pahwa, A. Malekpour, and B. Natarajan, “Hierarchical architecture for integration of rooftop pv in smart distribution systems,” IEEE Transactions on Smart Grid, vol. PP, no. 99, pp. 1–1, 2017.

[3] Y. Yang, P. Enjeti, F. Blaabjerg, and H. Wang, “Wide-scale adoption of photovoltaic energy: Grid code modifications are explored in the distribution grid,” IEEE Ind. Appl. Mag., vol. 21, no. 5, pp. 21–31, Sept 2015.

[4] M. J. E. Alam, K. M. Muttaqi, and D. Sutanto, “An approach for online assessment of rooftop solar pv impacts on low-voltage distribution  networks,” IEEE Transactions on Sustainable Energy, vol. 5, no. 2, pp.663–672, April 2014.

[5] J. Jayachandran and R. M. Sachithanandam, “Neural network-based control algorithm for DSTATCOM under nonideal source voltage and varying load conditions,” Canadian Journal of Electrical and Computer Engineering, vol. 38, no. 4, pp. 307–317, Fall 2015.