Power Quality Improvement in Solar Fed Cascaded Multilevel Inverter with Output Voltage Regulation Techniques

ABSTRACT:

The presence of harmonics in solar Photo Voltaic (PV) energy conversion system results in deterioration of power quality. To address such issue, this paper aims to investigate the elimination of harmonics in a solar fed cascaded fifteen level inverter with aid of Proportional Integral (PI), Artificial Neural Network (ANN) and Fuzzy Logic (FL) based controllers. Unlike other techniques, the proposed FLC based approach helps in obtaining reduced harmonic distortions that intend to an enhancement in power quality. In addition to the power quality improvement, this paper also proposed to provide output voltage regulation in terms of maintaining voltage and frequency at the inverter output end in compatible with the grid connection requirements. The simulations are performed in the MATLAB / Simulink environment for solar fed cascaded 15 level inverter incorporating PI, ANN and FL based controllers. To exhibit the proposed technique, a 3 kWp photovoltaic plant coupled to multilevel inverter is designed and hardware is demonstrated. All the three techniques are experimentally investigated with the measurement of power quality metrics along with establishing output voltage regulation.

KEYWORDS:

  1. Harmonics
  2. Intelligent control
  3. Multilevel inverter
  4. Photovoltaic’s
  5. Power quality
  6. Voltage regulation

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The voltage regulation topology along with power quality improvement is considered and implemented both in simulation and experimental setup for a solar fed 15 level inverter. While considering the results, it is found that FLC presents better results for VR while considering the variations at the input solar PV. Despite this, FLC is considered for the nine-level by [23], but the implementation is carried out with the DC power supplies without utilizing the solar panels. All the other methods are implemented for low power and lesser levels of MLI topology. Commercial utilization of MLI by providing the constant output voltage is investigated, and the experimental results prove the effectiveness of the proposed system. The method is applicable for the users require grid interaction along with the power quality improvement.

REFERENCES:

[1] S. Karekezi and T. Ranja, Renewable technologies in Africa. London, U.K.: Zed Books, 1997.

[2] S. Karekezi and W. Kithyoma, “Renewable energy strategies for rural africa: Is a PV-led renewable energy strategy the right approach for providing modern energy to the rural poor of sub-saharan africa?” Energy Policy, vol. 30, nos. 11_12, pp. 1071_1086, Sep. 2002.

[3] S. Karekezi andW. Kithyoma, “Renewable energy in Africa: Prospects and limits in Renewable energy development,” Workshop Afr. Energy Experts Operationalizing NEPAD Energy Initiative, vol. 1, pp. 1_30, 2-4 Jun. 2003. Jun. 2017. [Online]. Available: https://sustainabledevelopment.un. org/content/documents/nepadkarekezi.pdf

[4] D.-R. Thiam, “Renewable decentralized in developing countries: Appraisal from microgrids project in senegal,” Renew. Energy, vol. 35, no. 8, pp. 1615_1623, Aug. 2010.

[5] F. Christoph, World Energy Scenarios: Composing energy futures to 2050. London, U.K.: World Energy Council, 2013.

Three-Phase Five-Level Grid Synchronized PV Inverter with MPPT for Micro-Grid Application

ABSTRACT:

This paper develops an interesting converter for three phase grid interface for photovoltaic panels. Here a new topology having least number of power semiconductor switches in the five level category is used. The converter consists of three basic sections viz. the photovoltaic source, a two phase inverter and a Scott-T transformer that converts the two-phase inverter output to three phases and connects to the grid. The control system is in the d-q reference frame which provides fast dynamic control response. A maximum power point tracking mechanism (MPPT) is used to generate the direct axis current reference in order to inject the maximum available power into the grid for any insolation. The converter has been designed and developed for 1kW. This is also experimentally validated.

KEYWORDS:

  1. Current referenced control
  2. Maximum Power Point
  3. Sine pulse width modulation
  4. Scott-T Transformer
  5. Isolated Grid Tied Inverter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The paper presents a reduced switched method for generating a five level voltage output from a PV system. The whole converter system consists of three stages, the PV system with MPPT control, the 16 switch two-phase converter and finally isolation stage using Scott-T transformer. The converter pumping the current towards the grid is controlled by taking the PV MPP output current and providing it as Id reference for the inverter. This Id reference current controls the Id value of the inverter current control loop. Two-phase 16 switch inverter topology consist of high frequency and low frequency stages. High frequency stage will have a maximum switching stress voltage of Vdd=2 and similarly low frequency unfolding stage will have a maximum stress voltage of Vdd. The inverter has a self-balanced dc link capacitor pairs without any complex control schemes. Proper simulation analysis for the five level inverter sourced from a PV which in turn fed to grid has done which conforms its application on grid tied applications. Hardware implementation for two-phase level is also made and waveforms were verified comparing with the simulation. Further section of hardware is to be done in future in order to detail verification and making a complete prototype model for analysis.

REFERENCES:

[1] B. Satish Naik , L. Umanand, K. Gopakumar and B. Subba Reddy, ”A New Two-Phase Five-Level Converter for Three-Phase Isolated Grid-Tied Systems With Inherent Capacitor Balancing and Reduced Component Count” IEEE Journal of Emerging and Selected Topics in Power Electronics., VOL. 6, NO. 3,pp 1325-1335 Sep. 2018

[2] Gautam A. Raiker, L. Umanand and B. Subba Reddy, ”Perturb and Observe with Momentum Term applied to Current Referenced Boost Converter for PV Interface” 2018 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES)

[3] Gautam A. Raiker , Subba Reddy B., Praveen C. Ramamurthy, L. Umanand, Abines S. G. and Shama G. Vasisht ”Solar PV interface to Grid-Tie Inverter with Current Referenced Boost Converter” 2018 IEEE 13th International Conference on Industrial and Information Systems(ICIIS)

[4] J. Rodrguez, J.-S. Lai, and F. Z. Peng, Multilevel inverters: A survey of topologies, controls, and applications, IEEE Trans. Ind. Electron., vol. 49, no. 4, pp. 724738, Aug. 2002

[5] A. Nabae, I. Takahashi, and H. Akagi, A new neutral-point-clamped PWM inverter, IEEE Trans. Ind. Appl., vol. IA-17, no. 5, pp. 518523, Sep. 1981

Study of a Five-Level PWM Rectifier Fed DC Motor Drive

ABSTRACT:

A simulation of a five-level sinusoidal pulse width modulation (SPWM) rectifier fed D.C motor is proposed. The proposed topology of a five-level rectifier can be regulate the output voltage using (SPWM) to obtain variable speed of a D.C motor with constant load torque. The main advantages of the SPWM rectifier system are to drive a D.C motor with constant and variation load torque, low harmonic distortion in A.C supply side. The PID speed controller is used to make constant speed when load torque increase or decrease about 20% of rated value and to improve the dynamic response of the system. The five-level SPWM rectifier fed separately excited D.C motor are studied and simulated under the MATLAB/SIMULINK program.

KEYWORDS:

  1. Five-level rectifier
  2. C motor drive
  3. PID speed controller
  4. SPWM

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The paper presents a study and modeling of a five level rectifier with SPWM technique as a DC motor driver. Several researches focused on constructing the circuit of multi-level rectifier with static load (RL). In this study the five level rectifier system has been tested with a dynamic load as a separately excited DC motor. The proposed system investigated in case of open loop system with A disturbance in load torque applied +-20%from rated load torque and that’s lead to dramatic variation in motor speed with respect  to desired speed. Furthermore the effect of THD for input current was considered. PID controller is applied to the proposed system with the same disturbance in load torque and the results shows a constant output speed at desired speed with minimum response percentage error.

REFERENCES:

[1] Muhammad H. Rashid, “Power Electronics Devices, Circuits, and Applications”, Fourth Edition, ISBN 978-0-13-312590-0, published by Pearson Education, 2014.

[2] Jun-ichi Itoh, Yuichi Noge, and Taketo Adachi, “A Novel Five-Level Three-Phase PWM Rectifier With Reduced Switch Count”, IEEE Transactions On Power Electronics, Vol. 26, No. 8, AUGUST 2011.

[3] N. A. Rahim, J. A. Jalil, “Single-Phase Five-Level PWM Rectifier”, Institute of Research Management & Monitoring, University of Malaya.

[4] Omar Turath Tawfeeq, “Single Tuned Passive Harmonics Filters Design For A Buck Type Rectifier D.C Motor Drive Using Fuzzy Controller”, International Journal of Engineering and Innovative Technology (IJEIT) Volume 4, Issue 11, May 2015.

[5] Vivek Kumar, AshishPatra, “Application of Ziegler-Nichols method for tuning of PID Controller”, International Journal of electrical and Electronic Engineers, Vol. No.8, Issue No. 02, July-Dec. 2016.

Residential Community Load Management based on Optimal Design of Standalone HRES with Model Predictive Control

ABSTRACT:

Microgrids being an important entity in the distribution system, and to get their full advantages by incorporating maximum distributed generation, standalone hybrid renewable energy systems (HRESs), being environmentally-safe and economically-efficient, are considered as the promising solution to electrify remote areas where the grid power is not available. In this work, a techno-economic investigation with an optimal design of HRES is presented to fulfill the domestic electricity need for a residential area of the Sherani district in the Province of Baluchistan, Pakistan. Nine case studies based on PV/wind/diesel/battery are analyzed based on net present cost (NPC), cost of energy (COE), and emission to decide the feasible solution. HOMER tool is utilized to accomplish modeling and simulation for economic analysis and optimal sizing. Simulation results demonstrated that HRES with PV-wind-battery is the most viable option for the specified area, and the optimal sizing of components are also obtained with $ 28,620 NPC and 0.311 $/kWh COE which shows 81.65% reduction in cost and 100% preserving in toxic emission while fulfilling 100% energy demand with 67.3% of excess energy. Furthermore, MATLAB/Simulink modeling for the optimally designed system is built for technical analysis while its effectiveness is proved by keeping dc and ac buses voltage constant, safe operating range of battery state of charge (SOC) with active power balance between HRES components, as well as efficient ac voltage quality, regardless of generation disturbances and load fluctuations. The output signal has total harmonic distortion (THD) of 0.30% as compared to 5.44% with the conventional control scheme. The novelty lies in the sequential application of both HOMER and MATLAB simulations of the proposed HRES model and validation of the proposition for the studied area; by using and implementing model predictive control (MPC) of a reconfigurable inverter.

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

Standalone HRES with PV-wind-battery is proposed as the optimal and economically most viable system, as determined by techno-economic studies carried out through HOMER and MATLAB along with FCS-MPC of a reconfigurable inverter, to fulfill the residential electricity requirement of Sherani district in the Province of Baluchistan, Pakistan. Firstly, optimal sizing of HRES components and economic investigation is performed through HOMER, while simulation studies for the suggested area with practical and real data of load profile as well as weather is investigated using different costs (capital, replacement, O&M), operating life, and efficiencies of HRES components, project lifetime, meteorological data assessment, and interest rate as the input parameters; load demand, resources availability, operating reserves, allowable capacity shortage, GHG emission penalties as optimization constraints; and NPC as decision variable. Out of nine possible optimal configurations namely PV-wind-battery, PV-wind-diesel-battery, PV-battery, PV diesel- battery, wind-diesel-battery, PV-wind-diesel, PV diesel, wind-diesel, and diesel-battery, as examined during this work, PV-wind-battery is obtained as the most feasible and economically viable configuration (i.e. winning plan) with minimum NPC ($ 28,620) and COE (0.311 $/kWh) which shows 81.65% reduction in cost and 100% preserving in toxic emission, while fulfilling 100% energy demand with 67.3% of excess energy. The proposed optimal HRES design (winning plan) comprises 13.4 kW PV, 4 kW wind, 3.88 kW converter, and 20 units of 2.37 kWh lead-acid battery. Optimal sizes of HRES components are then used to design a management and control strategy in MATLAB/Simulink with finite control set model predictive control (FCS-MPC) of reconfigurable inverter for technical analysis based on power balance between HRES elements, constant dc and ac voltages, safe operating range of battery SOC, efficient ac voltage quality, during variations of PV irradiance, wind speed, as well as load demand. The results are validated through simulations with total harmonic distortion (THD) of 0.30% which is well below the allowable limit according to IEEE-929 and IEEE-519 standards as compared to 5.44% THD with the conventional PI control scheme.

The presented scheme would be an assessing tool for the governments, energy sector/microgrid planners, model designers, and researchers to investigate suitable policies, mechanisms, effective and efficient design of HRESs. An increasing, unpredictable and abrupt load demand of the society can be handled by integrating more renewable generation in terms of a reliable, economical, and environment-friendly scenarios with an understanding of intermittent generation profile. The future work includes microgrid reconfiguration under inverter and rectification mode to control the voltage and frequency during the standalone mode, and power flow during the grid-connected mode.

REFERENCES:

[1] E. Muh and F. Tabet, “Comparative analysis of hybrid renewable energy systems for off-grid applications in Southern Cameroons,” Renew. Energy, vol. 135, pp. 41–54,2019.

[2] O. Krishan and S. Suhag, “Techno-economic analysis of a hybrid renewable energy system for an energy poor rural community,” J. Energy Storage, vol. 23, no. November 2018, pp. 305–319, 2019.

[3] J. Kumari, P. Subathra, J. Edwin Moses, and D. Shruthi, “Economic analysis of hybrid energy system for rural electrification using homer,” Proc. IEEE Int. Conf. Innov. Electr. Electron. Instrum. Media Technol. ICIEEIMT 2017, vol. 2017-Janua, no. 978, pp. 151–156, 2017.

[4] W. Ullah, S. Noor, and A. Tariq, “The development of a basic framework for the sustainability of residential buildings in Pakistan,” Sustain. Cities Soc., vol. 40, no. January, pp. 365–371, 2018.

[5] “Greenhouse Gas (GHG) Emissions.” [Online]. Available: https://www.epa.gov/ghgemissions. [Accessed: 14-Dec- 2019].

Reliability evaluation of MPPT based interleaved boost converter for PV system

ABSTRACT:

The demand for power supply and depletion of the conventional energy sources are increasing drastically. So to overcome this problem, the best alternative power generation for conventional fossil fuel is Photovoltaic solar cell  based system because of its advantage of pollution free and its availability in abundance with free of cost. In the MPPT based PV system the converters are the most sensitive part. Therefore to provide uninterrupted power supply without compromising the quality of power, reliability evaluation of interleaved boost converter becomes necessary. MATLAB/Simulink is used for the simulation studies and to determine the power losses of various components of the converter which is used in calculating the failure rates and reliability of the interleaved boost converter. Reliability studies of IBC have not been studied much. However there exists few literature in which reliability expression has been developed using Markov technique which is a more complex method as compare to Reliability Block Diagram (RBD). Therefore this paper proposes reliability modeling and reliability evaluation of Interleaved boost converter in MPPT based photo-voltaic system by using simple RBD method.

KEYWORDS:

  1. Maximum Power Point Tracking (MPPT)
  2. Photovoltaic systems
  3. Reliability
  4. Failure rate
  5. Reliability Block diagram(RBD)
  6. Interleaved Boost Converter (IBC)

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The modeling of Interleaved boost converter is discussed stepwise along with its simulation results with the help of MATLAB/SIMULINK. The failure rates of each component of IBC and the whole IBC are determined. The RBD model is developed for a conventional boost converter and IBC and those are a series system and a parallel system respectively. With the help of this RBD the overall reliability evaluation and MTTF calculation are done for the IBC used in grid connected PV system. The interleaved boost converter acts as a power converter and MPP tracker as well because of its high reliable nature. The reliability evaluation can be done for the other topologies of these converters which are implemented in various other power generation system.

REFERENCES:

[1] TRISHAN ESRAM AND PATRICK L. CHAPMAN, “COMPARISON OF Photovoltaic Array Maximum Power Point Techniques”, IEEE Transactions on Energy Conversion, Vol.22, No.2, June, 2007.

[2] A. E. Khosroshahi, M. Abapour, and M. Sabahi, “Reliability evaluation of conventional and interleaved DC-DC boost converters,” IEEE Trans. Power Electron., vol. 30, no. 10, pp. 5821-5828, Oct. 2015.

[3] M.H. Taghvaee, M.A.M. Radzi, S.M. Moosavain, H. Hizam, and M.H. Marhaban, “A current and future study on non-isolated DC-DC converters for photovoltaic applications,” Renew. and Sustain. Energy, vol. 17, pp. 216-227, 2013.

[4] D. Sera, R. Teodorescu, and P. Rodriguez, “PV panel model based on datasheet values,” In Proc .IEEE. ISIE, pp. 2392-2398, Jun. 2007.

[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, May. 2009.

Recursive Digital Filter Based Control for Power Quality Improvement of Grid Tied Solar PV System

ABSTRACT:

This work deals with the implementation of a control approach for an active power transfer between solar photovoltaic (PV) array and the grid/ load along-with power quality improvement by eliminating harmonics and compensating reactive power required by the load in the distribution network. The power quality (PQ) problems at the point of intersection (PIC), are increasing preeminently with respect to voltage and current harmonics due to integration of renewable sources. The recursive digital filter control implemented here for PV grid interfaced system is efficient in improving PQ indices by operating round the clock and ensuring power transfer between utility grid and connected loads. The prominence of the control algorithm lies in the efficient switching of VSC, by generating reference grid currents, which are obtained through indirect current control technique. The recursive digital filter is utilized for processing the load currents and extracting the active power component of them. These active power components of load currents are used for generating the reference grid currents in this system. A prototype of the system is developed in the laboratory and its performance is studied for varying loads, changing solar insolation, and voltage swell, voltage sag and voltage distortion conditions.

KEYWORDS:

  1. Solar PV Generation
  2. Distribution Static Compensator (DSTATCOM)
  3. Power Quality
  4. Recursive Digital Filter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The performance of the grid tied PV system has been validated under weak grid conditions. Experimental validation has been performed for conditions of nonlinear load, at decrease of solar insolation, load injection, voltage swell and voltage sag conditions, unbalance and distortion. The control structure based on recursive digital filter, alleviates the complexity of the system and is easy to implement in the system. The switching pulses of VSC are generated by utilizing reference currents obtained by this control approach. In accordance to the IEEE- 519 standard, the grid current THD is obtained less than 5 %. Satisfactory performance based on experimental validation, has been obtained for the system.

REFERENCES:

[1] H. M. Bilal and A. Z. Khan, “Economic planning of network for integration of renewable: A review,” Proc. Pow. Gen. Sys. Renew. Ener. Tech. (PGSRET), pp. 1-3, 2015.

[2] I. Akhtar, S. Kirmani and M. Jamil, “Analysis and design of a sustainable microgrid primarily powered by renewable energy sources with dynamic performance improvement,” IET Renew. Pow. Gen., vol. 13, no. 7, pp. 1024-1036, 2019.

[3] X. Liang, “Emerging Power Quality Challenges Due to Integration of Renewable Energy Sources,” IEEE Trans. Indus. Appl., vol. 53, no. 2, pp. 855-866, March-April 2017.

[4] M. D’Antonio, C. Shi, B. Wu and A. Khaligh, “Design and Optimization of a Solar Power Conversion System for Space Applications,” IEEE Trans. Indus. Appl., vol. 55, no. 3, pp. 2310-2319, May-June 2019.

[5] K. R. Sree, A. K. Rathore, E. Breaz and F. Gao, “Soft-Switching Non- Isolated Current-Fed Inverter for PV/Fuel Cell Applications,” IEEE Trans. Indus. Appl., vol. 52, no. 1, pp. 351-359, Jan.-Feb. 2016

Power Quality Improvement of Grid-Connected Photovoltaic Systems Using Trans-Z-Source Inverter Under Partial Shading Condition

ABSTRACT:

Voltage-source inverter has been used widely in traditional photovoltaic systems which have limitations. To overcome, Z-source inverter has been introduced. In spite of all the features introduced in Z-source inverter, its configuration has been improved over the years, like trans-Z-source inverter which has added advantages compared to traditional inverters, namely buck–boost feature, lesser passive elements, and higher voltage boost gain. In this paper, photovoltaic arrays are connected to the grid via the trans-Z-source inverter with the aim of improving its power quality. Moreover, the shoot through duty ratio is kept constant in the switching control method to add features like lower voltage stress (higher reliability), lower total harmonic distortion (lower maintenance cost), and higher voltage boost ratio. To evaluate the precision of the proposed system, the photovoltaic system is simulated on a standard grid and under partial shading condition which brings about voltage sag, and hence, a dynamic voltage restorer is used to mitigate voltage sag. Simulation results are presented to verify the validation of the proposed photovoltaic system in terms of voltage and current THD reducing 78.2% and 19.7%, respectively.

KEYWORDS:

  1. PV system
  2. Trans-Z-source inverter
  3. THD
  4. Partial shading
  5. Voltage sag
  6. DVR

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a PV system is connected to the IEEE 15-bus test network via trans-ZSI with the aim of power quality improvement, plus MCBC control is used to decrease voltage and current THD, and more importantly, to reduce voltage stress across the switches. The results indicate that applying the trans-ZSI and an appropriate switching method improve the power quality of the PV system to a considerable extent. Besides, the cost, volume, and weight of this inverter are low because of having no low-frequency ripples of the output voltage. What is more, as the shoot through does not damage the inverter, the reliability of the inverter is higher. In turn, not only is the reliability of this inverter higher, but also its maintenance cost is lower. The proposed PV system is also studied under partial shading conditions to validate its performance when there are some voltage sags. So, a DVR is employed to detect voltage sags and then mitigate them once partial shading happens. Two conclusions can be drawn from cases C and D: The voltage amplitude is roughly fallen back to its rated value, and the voltage THD is reduced when trans-ZSI is used. To summarize, the results illustrate that the PV system operates accurately with the trans-ZSI, as opposed to the PV systems with traditional VSI.

REFERENCES:

Abdulkadir M, Samosir AS, Yatim AHM, Yusuf ST (2013) A new approach of modelling, simulation of MPPT for photovoltaic system in simulink model. ARPN J Eng Appl Sci 8(7):488–494

Ajaykumar T, Manmadharao S, Kumar NG, Venkateswarlu G (2017) Compensation of unbalanced voltage sag/swell by multilevel inverter-based dynamic voltage restorer. Int J Pure Appl Math 114(7):11–20

Al Hosani K, Nguyen TH, Al Sayari N (2018) An improved control strategy of 3P4W DVR systems under unbalanced and distorted voltage conditions. Int J Electr Power Energy Syst 98:233–242

Bidram A, Davoudi A, Balog RS (2012) Control and circuit techniques to mitigate partial shading effects in photovoltaic arrays. IEEE J Photovolt 2:532–546

Boonchiam P, Mitholananthan N (2008) Understanding of dynamic voltage restorers through MATLAB simulation. Thammasat Int J Sci Technol 11(3):1–6

Power Quality Improvement and PV PowerInjection by DSTATCOM with Variable DC Link Voltage Control from RSC-MLC

ABSTRACT:

The study proposes a method to optimize dc-link voltage of Distribution Static Compensator (DSTATCOM) based on load compensation requirement using Reduced Switch Count Multi-Level Converter (RSC-MLC) integrated with Photo-Voltaic (PV) system. The proposed method is capable of compensating reactive power, unbalance and harmonics demanded by three phase unbalanced and non-linear loads connected to the distribution side, leading to improvement of power quality. It is also capable of providing real power support to the load and thus prevents source from getting over loaded whenever required. During off-peak loads, the dc-link voltage can be brought down to a lower value, which will reduce the voltage-stress across switches of inverter and minimizes the switching losses. The variation of dc-link voltage is provided using RSC-MLC which requires dc voltage supply. This method utilizes renewable resources of energy such as solar cells as the dc voltage source. The output voltage of PV panel is boosted to a higher value using High Gain Boost Converter (HGBC) and given to RSC-MLC. The maximum power point tracking (MPPT) of PV panels is achieved by using Perturb and Observe (P & O) algorithm. The results have been verified through simulation and experimental studies.

KEYWORDS:

  1. DC-link voltage
  2. DSTATCOM
  3. Power Quality
  4. PV system
  5. Reduced Switch Count Multi Level Converter (RSCMLC)
  6. Switching Losses

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

A new method is proposed to regulate the dc-link voltage using RSC-MLC without affecting the performance of DSTATCOM. It also uses renewable energy resources for obtaining dc voltage source such as PV panels, Fuel cells. Using PV panels effectively enables it to deliver real power as well as compensation to the load during day time and work purely as DSTATCOM for power quality improvement at night. It can be observed from simulation and experimental results that compensation for reactive power and harmonics has been achieved effectively. The source current is balanced, sinusoidal, distortion-free and with improved power factor. The %THD has reduced significantly after compensation. Also, due to reduced dc-link voltage at lesser loads, voltage stress across the switches has reduced and switching losses are minimized to a great extent, increasing the life-time and efficiency of DSTATCOM. Hence, it can be a good alternative for power quality improvement and real power support to the load.

REFERENCES:

[1] J. Arrillaga, N. R. Watson, “Power system harmonics,” John Wiley and Sons, 2004.

[2] A. Ghosh A, G. Ledwich, “Power Quality Enhancement using Custom Power Devices,” Springer Science and Business Media, 2012.

[3] M. H. J. Bollen, “Understanding Power Quality Problems: Voltage Sags and Interruptions,” Wiley – IEEE press, Piscataway, NJ, USA, 2002 .

[4] B. Singh, S. R. Arya, C. Jain, S. Goel, “Implementation of Four-leg Distribution Static Compensator,” IET Gener. Transm. Distrib., vol. 8, no. 6, pp. 1127-1139, June 2014.

[5] R. P. Tondare, S. P. Gawande, M. R. Ramteke, “Modeling of Split Capacitor Based DSTATCOM and Voltage Balancing Scheme for Load Compensation,” International Conference on Emerging Trends in Communication, Control, Signal Processing and Computing Applications (C2SPCA), Bangalore, pp. 1-6, 2013.

 

Power optimisation scheme of inductionmotor using FLC for electric vehicle

ABSTRACT:

In electric vehicles (EVs) and hybrid EVs, energy efficiency is essential where the energy storage is limited. Adding to its high stability and low cost, the induction motor efficiency improves with loss minimisation. Also, it can consume more power than the actual need to perform its working when it is operating in less than full load condition. This study proposes a control strategy based on the fuzzy logic control (FLC) for EV applications. FLC controller can improve the starting current amplitude and saves more power. Through the MATLAB/SIMULINK software package, the performance of this control was verified through simulation. As compared with the conventional proportional integral derivative controller, the simulation schemes show good, high-performance results in time-domain response and rapid rejection of system-affected disturbance. Therefore, the core losses of the induction motor are greatly reduced, and in this way improves the efficiency of the driving system. Finally, the suggested control system is validated by the experimental results obtained in the authors’ laboratory, which are in good agreement with the simulation results.

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

When IM operates in less than full load condition, it can consume more power than needed. This excess power is in the form of heat. By using the FLC the starting current amplitude can be controlled and more power can be saved during this time. The inputs of the fuzzy controller are the error of speed and change of error which are used in the outer loop for producing an equivalent controller term. In this paper, a simulation study was conducted on a 50 hp IM-driven EV. Different performance indicators are tested such as peak overshoot, steady-state error, rise time, and settling time. The results showed that the phase current in the suggested system includes fewer loss components (less amplitude) with the same order components. The amplitudes of loss are reduced on the average for the actual torque in the steady state. It achieves a smooth torque and improves system performance. The simulation results of the suggested FLC scheme showed very good stability and better performance over the conventional PID controller in rising time, settling time, and peak overshoot. The proposed control system is validated by the experimental results which are in good agreement with the simulation results.

REFERENCES:                                         

[1] Sato, E.: ‘Permanent magnet synchronous motor drives for hybrid electric vehicles’, IEEJ Trans. Electr. Electron. Eng., 2007, 2, (2), pp. 162–168

[2] Agency, I.E.: ‘Global EV outlook 2016: beyond one million electric cars’ (OECD Publishing)

[3] Sayed, K.: ‘Zero-voltage soft-switching DC-DC converter-based charger for LV battery in hybrid electric vehicles’, IET Power Electron., 2019, 12, (13), pp. 3389–3396

[4] Gomez, J.C., Morcos, M.M.: ‘Impact of EV battery chargers on the power quality of distribution systems’, IEEE Power Eng. Rev., 2002, 22, (10), pp. 63–63

[5] Stephan, C.H., Sullivan, J.: ‘Environmental and energy implications of plug in hybrid-electric vehicles’, Environ. Sci. Technol., 2008, 42, (4), pp. 1185– 1190

Power Flow Control of Interconnected AC-DC Microgrids in Grid-Connected Hybrid Microgrids Using Modified UIPC

ABSTRACT:

This paper introduces a new approach for power flow control of interconnected AC-DC microgrids in grid-connected hybrid microgrids based on implementing a modified unified interphase power controller (UIPC). A typical grid-connected hybrid microgrid including one AC microgrid and one DC microgrid is considered as studied system. Instead of using the parallel-connected power converters, these microgrids are interconnected using a modified UIPC. As the first contribution of this paper, the conventional structure of UIPC, which uses three power converters in each phase, is modified so that a reduced number of power converters is implemented for power exchange control between AC-DC microgrids. The modified structure includes one power converter in each phase, named as line power converter (LPC), and a power converter which regulates the DC bus voltage, named as bus power converter (BPC) here. The AC microgrid is connected to the main grid through the LPCs which their DC buses are linked and can operate in capacitance mode (CM) or inductance mode (IM). A fuzzy logic controller is used in the control structure of the LPCs. The fuzzy inference system is optimized based on H∞ filtering method to reduce the errors in membership functions design. Through the BPC, the DC voltage of LPCs is supplied by the DC microgrid. However, since the DC microgrid voltage is provided here by a PV system, the DC link voltage of the LPCs is fluctuating. Thus, as the second contribution, to stabilize the DC link fluctuations, a new nonlinear disturbance observer based robust multiple-surface sliding mode control (NDO-MS-SMC) strategy is presented for DC side control of the BPC. The simulation results confirm the effectiveness of the proposed power flow control strategy of the improved UIPC for hybrid microgrids.

KEYWORDS:

  1. Hybrid microgrid
  2. UIPC
  3. Power control
  4. Disturbance observer
  5. Multi-surface SMC

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The hybrid microgrid structure is the most probable option in the future smart grids to gather together the renewable resources as well as AC/DC loads. This is due to the fact that this structure has the merits of both AC and DC microgrids simultaneously. One conventional problem with this structure is the power exchange control between interconnected AC and DC microgrids. In this study, a UIPC based solution has been proposed as a superior alternative to the parallel-connected power converters which have brought many problems. A modified structure of the UIPC has firstly been proposed and then effective control strategies have been introduced for the modified UIPC. The simulation results validated the modified model as well as the power exchange control performance between AC and DC microgrids.

REFERENCES:

[1] Runfan Zhang, Branislav Hredzak, “Distributed Finite-Time Multi-Agent Control for DC Microgrids with Time Delays”, IEEE Transactions on Smart Grid, Early Access, 2018.

[2] Kumar Utkarsh, et al, “Distributed Model-predictive Real-time Optimal Operation of a Network of Smart Microgrids“, IEEE Transactions on Smart Grid, Early Access, 2018.

[3] Haifeng Qiu, et al, ” Bi-level Two-stage Robust Optimal Scheduling for AC/DC Hybrid Multi-microgrids“, IEEE Transactions on Smart Grid, Early Access, 2018.

[4] Pengfeng Lin, et al, “A Distributed Control Architecture for Global System Economic Operation in Autonomous Hybrid AC/DC Microgrids“, IEEE Transactions on Smart Grid, Early Access, 2018.

[5] Daniel E. Olivares, et al, “Trends in Microgrid Control“, IEEE Transactions on Smart Grid Volume: 5, Issue: 4, pp. 1905 – 1919, 2014.