Implementation of Solar Photovoltaic System with Universal Active Filtering Capability

ABSTRACT:

In this work, a novel technique based on second order sequence filter and proportional resonant controller is pro- posed for control of universal active power filter integrated with PV array system (UAPF-PV). Using a second order sequence filter and sampling it at zero crossing of instant of the load voltage, the active component of distorted load current is estimated which is further used to generate reference signal for shunt active filter. The proposed method has good accuracy in extracting fundamental active component of distorted and unbalanced load currents with reduced mathematical computations. Along with power quality improvement, the system also generates clean energy through the PV array system integrated to its DC-bus. The UAPF-PV system integrates benefits of power quality improvement and distributed generation. The system performance is experimentally evaluated on an experimental prototype in the laboratory under a variety of disturbance conditions such as PCC voltage fall/rise, load unbalancing and variation in solar irradiation.

KEYWORDS:

  1. Power quality
  2. Universal active power filter
  3. Adaptive filtering
  4. Photovoltaic system
  5. Maximum power point tracking
  6.  Sequence filter

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. System configuration of UAPF-PV

EXPECTED SIMULATION RESULTS:

(a) Performance under Load Removal

(b) Performance under Load Addition

Fig. 2. Dynamic Performance under load Unbalance Condition

(a) Performance under PCC Voltage Dip Condition

(b) Performance under Swell Condition

Fig. 3. Dynamic Performance under PCC Voltage dip/rise Condition

Fig. 4. UAPF-PV Response under irradiation Change Condition

Fig. 6. Salient Signals in Extraction of Fundamental Positive Sequence Load Current

(a) Salient Signals in Shunt Active Filter Control

(b) Salient Signals in series active filter Control

Fig. 7. Salient Signals in UAPF-PV Control

CONCLUSION:

The performance of a novel control technique for solar PV system with universal active filtering has been evaluated. The fundamental positive sequence component of nonlinear load current is extracted using a second order sequence filter along with a zero cross detection technique. The series active filter is controlled using a proportional resonant controller implemented in domain along with feedforward component. The system performs satisfactorily under disturbances such as PCC voltage dip/rise, changes in solar radiation and load disturbances. Apart from improving power quality, the system also supplies power from PV array into grid. A comparison of the proposed control shows that the system has improved performance as compared to conventional control techniques with slightly lower computational burden. The system integrates distributed generation along with enhancing power quality of distribution system.

REFERENCES:

[1] S. J. Pinto, G. Panda, and R. Peesapati, “An implementation of hybrid control strategy for distributed generation system interface using xilinx system generator,” IEEE Transactions on Industrial Informatics, vol. 13, no. 5, pp. 2735–2745, Oct 2017.

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

[3] B. Singh, M. Kandpal, and I. Hussain, “Control of grid tied smart pvdstatcom system using an adaptive technique,” IEEE Transactions on Smart Grid, vol. PP, no. 99, pp. 1–1, 2017.

[4] Y. Singh, I. Hussain, S. Mishra, and B. Singh, “Adaptive neuron detection-based control of single-phase spv grid integrated system with active filtering,” IET Power Electronics, vol. 10, no. 6, pp. 657–666, 2016.

[5] C. Jain and B. Singh, “An adjustable dc link voltage-based control of multifunctional grid interfaced solar pv system,” IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 5, no. 2, pp. 651–660, June 2017.

Grid to Vehicle and Vehicle to Grid Energy Transfer using Single-Phase Bidirectional AC DC Converter and Bidirectional DC – DC converter

ABSTRACT:

In this paper, a configuration of a single-phase bidirectional AC-DC converter and bidirectional DC-DC converter is proposed to transfer electrical power from the grid to an electrical vehicle (EV) and from an EV to the grid while keeping improved power factor of the grid. In first stage, a 230 V 50 Hz AC supply is converted in to 380V dc using a single-phase bidirectional AC-DC converter and in the second stage, a bidirectional buck–boost dc-dc converter is used to charge and discharge the battery of the PHEV (Plug-in Hybrid Electric Vehicle). In discharging mode, it delivers energy back to the grid at 230V, 50 Hz. A battery with the charging power of 1.2 kW at 120V is used in PHEV. The buck-boost DC-DC converter is used in buck mode to charge and in a boost mode to discharge the battery. A proportional-integral (PI) controller is used to control the charging current and voltage. Simulated results validate the effectiveness of proposed algorithm and the feasibility of system.

KEYWORDS:

  1. Plug-in Hybrid Electric Vehicle (PHEV)
  2. Bidirectional AC-DC Converter
  3. DC-DC Converter
  4. Vehicle to grid (V2G)
  5. Electric drive vehicle (EDVs)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1 Proposed configuration for V2G and G2V Energy transfer

EXPECTED SIMULATION RESULTS:

Fig.2 Charging and discharging of PHEV battery (Full profile)

Fig.3 Charging and discharging of PHEV battery (in large view)

Fig.4. Discharging and Charging of PHEV battery demonstrating unity

Power factor operation

CONCLUSION:

The proposed converter has delivered the AC current to/and from the grid at unity power factor and at very low current harmonics which ultimately prolongs the life of the converter and the battery and minimizes the possibility of distorting the grid voltage. It also enables V2G interactions which could be utilized to improve the efficiency of the grid.

REFERENCES:

[1] Young-Joo Lee, Alireza Khaligh, and Ali Emadi, “Advanced Integrated Bidirectional AC/DC and DC/DC Converter for Plug-In Hybrid Electric Vehicles,” IEEE Trans. on Vehicular Tech. vol. 58, no. 8, pp. 3970-3980, Oct, 2009.

[2] Bhim Singh, Brij N. Singh, Ambrish Chandra, Kamal Al-Haddad, Ashish Pandey and Dwarka P. Kothari, “A review of single-phase improved power quality ac–dc converters,” IEEE Trans. Industrial Electronics, vol. 50, no. 5, pp. 962-981, Oct. 2003.

[3] M.C. Kisacikoglu, B. Ozpineci and L.M. Tolbert, “Examination of a PHEV bidirectional charger system for V2G reactive power compensation,” in Proc. of Twenty-Fifth Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2010, 21-25 Feb.2010, pp.458-465.

[4] M.C. Kisacikoglu, B. Ozpineci and L.M. Tolbert, “Effects of V2G reactive power compensation on the component selection in an EV or PHEV bidirectional charger,” in Proc. of Energy Conversion Congress and Exposition (ECCE), 2010 IEEE, 12-16 Sept. 2010, pp.870-876.

[5] W. Kempton and J. Tomic, “Vehicle-to-grid power fundamentals: Calculating capacity and net revenue,” J. Power Sources, vol. 144, no. 1, pp. 268–279, Jun. 2005.

Grid Interactive Bidirectional Solar PV Array Fed Water Pumping System

ABSTRACT:

This paper proposes a grid interactive bidirectional solar water pumping system using a three phase induction motor drive (IMD). A single phase voltage source converter (VSC) is used to direct the flow of power from grid supply to the pump and back to the grid from SPV array. A boost converter is used for the maximum power point tracking (MPPT) of the SPV array. A smart power sharing control is proposed, with preference given to the power from SPV array over the grid power. Moreover, the grid input power quality is also improved. Various modes of operation of the pump are elaborated and the performance of the system at starting, in steady state and dynamic conditions are simulated. The simulated results show the novelty and the satisfactory performance of the system.

KEYWORDS:

  1. Solar water pump
  2. MPPT
  3. Grid interactive
  4. Smart power sharing

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Configuration for the single phase grid interactive SPV water pumping system

EXPECTED SIMULATION RESULTS:

Fig. 2(a) Starting performance of the proposed system in mode I

Fig. 2(b) Steady state performance of the proposed system in mode I

Fig. 2(c) Performance of the system in mode I under decreasing radiation from 800 W/m2 to 500 W/m2

Fig. 2(d) Performance of the system in mode I under increasing radiation from 500 W/m2 to 800 W/m2

Fig. 3(a) Starting performance of the system in mode II

Fig. 3(b) Steady state performance of the system in mode II

Fig. 4(a) Characteristics of the system in mode III with decrease in Radiation

Fig. 4(b) Characteristics of the system in mode III with increase in Radiation

Fig. 5(a) Characteristics of the system in mode IV with increase in Radiation

Fig. 5 (b) Characteristics of the system in mode III with decrease in radiation

CONCLUSION:

A single phase grid interactive solar water pumping is presented in the paper. Various modes of operation are identified and simulated in MATLAB Simulink environment. The simulated results have demonstrated the satisfactory performance of the system at starting, and in steady and dynamic conditions. The proposed system not only is able to share the power between two sources but it also improves the quality of power drawn. Moreover, the system manages to feed the power from the SPV array as in when required. The system is well suited for the rural and agricultural usage.

REFERENCES:

[1] J. Zhu, “Application of Renewable Energy,” in Optimization of Power System Operation, Wiley-IEEE Press, 2015, p. 664.

[2] Z. Ying, M. Liao, X. Yang, C. Han, J. Li, J. Li, Y. Li, P. Gao, and J. Ye, “High-Performance Black Multicrystalline Silicon Solar Cells by a Highly Simplified Metal-Catalyzed Chemical Etching Method,” IEEE J. Photovolt., vol. PP, no. 99, pp. 1–06, 2016.

[3] M. Steiner, G. Siefer, T. Schmidt, M. Wiesenfarth, F. Dimroth, and A. W. Bett, “43% Sunlight to Electricity Conversion Efficiency Using CPV,” IEEE J. Photovolt., vol. PP, no. 99, pp. 1–5, 2016.

[4] M. Kolhe, J. C. Joshi, and D. P. Kothari, “Performance analysis of a directly coupled photovoltaic water-pumping system,” IEEE Trans. Energy Convers., vol. 19, no. 3, pp. 613–618, Sep. 2004.

[5] S. R. Bhat, A. Pittet, and B. S. Sonde, “Performance Optimization of Induction Motor-Pump System Using Photovoltaic Energy Source,” IEEE Trans. Ind. Appl., vol. IA-23, no. 6, pp. 995–1000, Nov. 1987.

Fuzzy Logic Based MPPT Control for a PV/Wind Hybrid Energy System

ABSTRACT:

In this paper, we present a modeling and simulation of a standalone hybrid energy system which combines two renewable energy sources, solar and wind, with an intelligent MPPT control based on fuzzy logic to extract the maximum energy produced by the two PV and Wind systems. Moreover, other classical MPPT methods were simulated and evaluated to compare with the FLC method in order to deduce the most efficient in terms of rapidity and oscillations around the maximum power point, namely Perturb and Observe (P&O), Incremental Conductance (INC) for the PV system and Hill Climbing Search (HCS) for the Wind generator. The simulation results show that the fuzzy logic technique has a better performance and more efficient compared to other methods due to its fast response, the good energy efficiency of the PV/Wind system and low oscillations during different weather conditions.

KEYWORDS:

  1. Hybrid energy system
  2. MPPT
  3. Fuzzy Logic Control (FLC)
  4. Wind system
  5. Photovoltaic system
  6. PMSG

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of fuzzy logic MPPT controller for PV system.

EXPECTED SIMULATION RESULTS:

Fig. 2. PV generator output power for different MPPT techniques.

Fig. 3. PV generator output voltage for different MPPT techniques.

Fig. 4. Mechanical power of wind turbine for different MPPT techniques.

Fig. 5. Power coefficient (Cp) for different MPPT techniques.

CONCLUSION:

In this work, an intelligent control based on fuzzy logic is developed to improve the performance and reliability of a PV/Wind hybrid energy system, also the implementation of the other conventional MPPT algorithms for compared with the FLC technique. For a best performance analysis of MPPT techniques on the system, the simulations are carried out under different operating conditions. Simulation results show that the fuzzy controller has a better performance because it allows with a fast response and high accuracy to achieve and track the maximum power point than the P&O, INC and HCS methods for the PV and Wind generators respectively.

REFERENCES:

[1] A.V. Pavan Kumar, A.M. Parimi and K. Uma Rao, “Implementation of MPPT control using fuzzy logic in solar-wind hybrid power system,” IEEE International Conference on Signal Processing, Informatics, Communication and Energy Systems (SPICES), India, 19-21 February, 2015.

[2] C. Marisarla and K.R. Kumar, “A hybrid wind and solar energy system with battery energy storage for an isolated system,” International Journal of Engineering and Innovative Technology, vol. 3, n°3, pp. 99-104, ISSN 2277-3754, September 2013.

[3] L. Qin and X. Lu, “Matlab/Simulink-based research on maximum power point tracking of photovoltaic generation,” Physics Procedia, 24, pp.10- 18, 2012.

[4] B. Bendib, F. Krim, H. Belmili, M. F. Almi and S. Boulouma, “Advanced fuzzy MPPT controller for a stand-alone PV system,” Energy Procedia, 50, pp.383-392, 2014.

[5] H. Bounechba, A. Bouzid, K. Nabti and H. Benalla, “Comparison of perturb & observe and fuzzy logic in maximum power point tracker for pv systems,” Energy Procedia, 50, pp.677-684, 2014.

Five-Level Reduced-Switch-Count Boost PFC Rectifier with Multicarrier PWM

ABSTRACT:

A multilevel boost PFC (Power Factor Correction) rectifier is presented in this paper controlled by cascaded controller and multicarrier pulse width modulation technique. The presented topology has less active semiconductor switches compared to similar ones reducing the number of required gate drives that would shrink the manufactured box significantly. A simple controller has been implemented on the studied converter to generate a constant voltage at the output while generating a five-level voltage waveform at the input without connecting the load to the neutral point of the DC bus capacitors. Multicarrier PWM technique has been used to produce switching pulses from control signal at a fixed switching frequency. Multi-level voltage waveform harmonics has been analyzed comprehensively which affects the harmonic contents of input current and the size of required filters directly. Full experimental results confirm the good dynamic performance of the proposed five-level PFC boost rectifier in delivering power from AC grid to the DC loads while correcting the power factor at the AC side as well as reducing the current harmonics remarkably.

KEYWORDS:

  1. Multilevel Converter
  2. Active Rectifier
  3. Multicarrier PWM
  4. Cascaded Control
  5. Power Quality

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Proposed five-level boost PFC rectifier with reduced number of switches

EXPECTED SIMULATION RESULTS:

Fig. 2. Experimental results from steady-state operation of the rectifier

Fig. 3. Experimental results during 50% increase in the load

Fig. 4. Experimental results during AC source voltage variation

Fig. 5. Experimental results during 25% raise in the DC voltage reference

CONCLUSION:

In this paper a reduced switch count 5-level boost PFC rectifier has been presented. A cascaded PI controller has been designed to regulate the output DC voltage and to ensure the unity power factor mode of the input AC voltage and current. Moreover, low harmonic AC current waveform has been achieved by the implemented controller and employing a small inductive filter at the input line. One of the main issues of switching rectifiers is the high switching frequency that has been reduced in this work using PWM technique through adopting multicarrier modulation scheme. Moreover, DC capacitors middle point has not been connected to the load that had required splitting the load to provide a neutral point. Using a single load with no neutral point makes this topology practical in real applications. Comprehensive experimental tests including change in the load, AC voltage fluctuation and generating different DC voltage values have been performed to ensure the good dynamic performance of the rectifier, adopted controller and switching technique. Moreover, the low THD of the input current has been measured to validate the advantage of multilevel waveforms in reducing harmonic contents and consequently diminishing the size of required filters at the input of the converters.

REFERENCES:

[1] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, “A review of three-phase improved power quality AC-DC converters,” Industrial Electronics, IEEE Transactions on, vol. 51, no. 3, pp. 641-660, 2004.

[2] M. Mobarez, M. Kashani, and S. Bhattacharya, “A Novel Control Approach For Protection of Multi-Terminal VSC Based HVDC Transmission System Against DC Faults,” IEEE Trans. Ind. Applications, vol. PP, no. 99, pp. 1-1, 2016.

[3] H. Mortazavi, H. Mehrjerdi, M. Saad, S. Lefebvre, D. Asber, and L. Lenoir, “A Monitoring Technique for Reversed Power Flow Detection With High PV Penetration Level,” IEEE Trans. Smart Grid, vol. 6, no. 5, pp. 2221-2232, 2015.

[4] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, Power electronics for renewable energy systems, transportation and industrial applications: John Wiley & Sons, 2014.

[5] H. Vahedi, H. Y. Kanaan, and K. Al-Haddad, “PUC converter review: Topology, control and applications,” in IECON 2015-41st Annual Conference of the IEEE Industrial Electronics Society, Japan, 2015, pp. 4334-4339.

Evaluation of Battery System for Frequency Control in Interconnected Power System with a Large Penetration of Wind Power Generation

ABSTRACT:

Recently, a lot of distributed generations such as wind power generation are going to be installed into power systems. However, the fluctuation of these generator outputs affects the system frequency. Therefore, introduction of battery system to the power system has been considered in order to suppress the fluctuation of the total power output of the distributed generation. For frequency analysis, we use the interconnected 2-area power system model. It is assumed that a small control area with a large penetration of wind power plants is interconnected into a large control area. In this system, the tie line power fluctuation is very large as well as the system frequency fluctuation. It is shown that the installed battery can suppress these fluctuations and that the effect of battery on suppression of fluctuations depends on the battery capacity. Then, the required battery capacity for suppressing the tie line power deviation within a given level is calculated.

KEYWORDS:

  1. Battery
  2. Distributed Generation
  3. Frequency
  4. Load Frequency Control (LFC)
  5. Power System
  6. Tie Line Power
  7. Wind Power Generation

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Battery system model.

EXPECTED SIMULATION RESULTS:

(a) Tie line power flow

(b) system frequency (Area 2)

Fig. 2. Impact of LFC control method.

  • (a) Tie line power flow

(b) System frequency (Area 2)

(c) Battery output

Fig. 3. Behaviors of tie line power flow, system frequency and battery

output with/without battery (Kb = 0.5, Tb = 0.5).

(a) Tie line power flow

(b) Battery stored energy

(c) Battery output

Fig. 4 Behaviors of tie line power and output and stored energy of battery (9OMWh, 1500MW)

CONCLUSION

In this paper, we have analyzed the impact of installed wind power generation and battery on the system frequency and the tie line power. In 2-area power systems, the tie line power fluctuation is remarkably large as well as the system frequency fluctuation. It has been made clear that the installed battery can suppress these fluctuations and that the effect of battery on suppression of these fluctuations depends on battery capacity. If the stored energy of battery reaches the full capacity, the battery output changes to zero suddenly and the large fluctuation is caused. Therefore, the stored energy needs to be controlled within the rated storage capacity. Based on this need, the required battery capacity for suppressing the tie line power deviation within a reference level has been calculated. If battery and LFC generator are controlled cooperatively, installation of battery with a larger capacity makes it possible to decrease LFC capacity of the conventional generators. In the near future, a new method to calculate the optimal battery storage capacity (MWh) and the appropriate power converter capacity (MW) for various kinds of wind power generation patterns and an effective control method of the battery system for reducing the battery capacity and LFC capability of the conventional power plants will be studied.

REFERENCES:

[1] W. El-Khattam and M. M. A. Salama, “Distributed generation technologies, definitions and benefits,” Electric Power Systems Research, vol. 71, issue 2, pp. 1 19-128, Oct. 2004.

[2] N. Jaleeli, L. S. VanSlyck, D. N. Ewart, L. H. Fink, and A. G. Hoffmann, “Understanding automatic generation control,” IEEE Trans. Power Syst., vol. 7, pp. 1106-1122, Aug. 1992.

[3] A. Murakami, A. Yokoyama, and Y. Tada, “Basic study on battery capacity evaluation for load frequency control (LFC) in power system with a large penetration of wind power generation,” T. IEE Japan, vol. 126-B, no. 2, pp. 236-242, Feb. 2006. (in Japanese)

[4] P. Kunder, “Power System Stability and Control, ” McGraw-Hill, 1994.

[5] A. J. Wood and B. F. Wollenberg, “Power Generation Operation and Control,” 2nd ed., Wiley, New York, 1966.

Direct Torque Control using Switching Table for Induction Motor Fed by Quasi Z-Source Inverter

ABSTRACT:

Z-source inverters eliminate the need for front-end DC-DC boost converters in applications with limited DC voltage such as solar PV, fuel cell. Quasi Z-source inverters offer advantages over Z-source inverter, such as continuous source current and lower component ratings. In this paper, switching table based Direct Torque Control (DTC) of induction motor fed by quasi Z-Source Inverter (qZSI) is presented. In the proposed technique, dc link voltage is boosted by incorporating shoot through state into the switching table. This simplifies the implementation of DTC using qZSI. An additional DC link voltage hysteresis controller is included along with torque and flux hysteresis controllers used in conventional DTC. The results validate the boost capability of qZSI and torque response of the DTC.

KEYWORDS:

  1. DTC
  2. qZSI
  3. DC-DC Converter
  4. DC Link Voltage
  5. Hysteresis Controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1: Block Diagram for DTC using Qzsi

EXPECTED SIMULATION RESULTS:

Fig. 2: Torque vs. Time

Fig. 3: Stator Phase ‘a’ Current

Fig. 4: Speed vs. Time

Fig. 5: DC Link Voltage

Fig. 6: Capacitor Voltage, VC1

CONCLUSION:

In this paper, direct torque control of induction motor fed by qZSI is presented. Dynamic torque response for step change obtained is 3 ms, which is needed for high performance applications. qZSI provides a single stage solution for drives with variable input DC voItage, instead of DC-DC converter cascaded with 3-leg inverter bridge. This paper presents a solution for drives with lesser DC input voItage availability and also requiring very fast torque response. The results shows that by introducing shoot through state in switching table of direct torque control, DC link voItage in qZSI is boosted. The DC link voItage hysteresis controller uses the input and capacitor voItage for controlling DC link voItage. If there is any disturbance in input voItage, the reference for capacitor voItage will be changed accordingly to maintain the DC link voItage.

REFERENCES:

[1] 1. Takahashi and Y. Ohmori, “High-performance direct torque control of an induction motor, ” IEEE Trans. Ind. Appl., vol. 25, no. 2, pp. 257-264, 1989.

[2] B.-S. Lee and R. Krishnan, “Adaptive stator resistance compensator for high performance direct torque controlled induction motor drives, ” in Industry Applications Conference, 1998. Thirty-Third lAS Annual Meeting. The 1998 IEEE, vol. I, Oct 1998, pp. 423-430 voLl.

[3] G. Buja and M. Kazmierkowski, “Direct torque control of pwm inverter-fed ac motors-a survey, ” IEEE Trans. Ind. Electron., vol. 51, no. 4, pp. 744-757, Aug 2004.

[4] F. Z. Peng, “Z-source inverter, ” IEEE Trans. Ind. Appl., vol. 39, no. 2, pp. 504-510, Mar 2003.

[5] F. Z. Peng, A. Joseph, J. Wang, M. Shen, L. Chen, Z. Pan, E. Ortiz-Rivera, and Y. Huang, “Z-source inverter for motor drives, ” IEEE Trans. Power Electron., vol. 20, no. 4, pp. 857-863, July 2005.

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

BLOCK DIAGRAM:

Fig. 1. Proposed SEIG-based WECS with VOC VSI.

EXPECTED SIMULATION RESULTS:

Fig. 2. Line voltage of theVSI in frame (400 V/div–5ms). (a) Simulation. (b) Experiment.

Fig. 3. Phase voltage of the VSI in frame (400 V/div–5 ms). (a) Simulation. (b) Experiment.

Fig. 4. Grid phase voltage (50 V/div–10 ms) and injected current (1 A/div–10 ms). (a) Simulation. (b) Experiment.

Fig. 5. Inverter phase voltage to be connected to the grid with only filter (50 V/div–10 ms). (a) Simulation. (b) Experiment.

Fig. 6. Harmonic spectrum of (a) injected current; (b) phase voltage

Fig. 7. Grid voltage (50 V/div–25 ms) and injected current (1 A/div–25 ms) under step change in the reactive power injected into grid. (a) Simulation. (b) Experiment.

Fig. 8. VSI response with filter for the grid and capacitor voltage (100 V/div–10 ms) with the injected line current (5 A/div–10 ms). (a) Simulation. (b) Experiment.

Fig. 9. Harmonic spectrum analysis with filter. (a) Injected current harmonic content. (b) Filter capacitor voltage harmonic content.

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 variablespeed 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.

Design of a PEV Battery Charger with High Power Factor using Half-bridge LLC-SRC Operating at Resonance Frequency

ABSTRACT:

This paper presents a two stage battery charger for plug-in electric vehicles (PEV) based on half-bridge LLC series resonant converter (SRC) operating at resonance frequency. The first stage is power factor correction (PFC) stage comprising of boost converter topology using hysteresis band control of inductor current. The PFC stage reduces the total harmonic distortion (THD) of the line current for achieving high power factor and regulates the voltage to follow the battery voltage at DC link capacitor. The input of the boost converter is a single phase 50 Hz, 220V AC from grid. At the second stage, a half bridge LLC-SRC is used for constant-current, constant-voltage (CC-CV) based battery charging and for providing galvanic isolation. The resonant converter is designed to operate around resonance frequency to have maximum efficiency and low turnoff current of power switches to reduce switching losses. The circuit is simulated using MATLAB Simulink with 1.5 kW maximum output power. Simulation results show that the PFC stage achieves THD less than 0.07% and high power factor value as 0.9976. The DC/DC stage meets all the CC-CV charging requirements of the battery over wide voltage range 320V—420V for depleted to fully charged battery.

KEYWORDS:

  1. LLC Resonant converter
  2. PEV battery charger
  3. PFC
  4. Hysteresis band control
  5. FHA

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Schematic of the proposed battery charger.

EXPECTED SIMULATION RESULTS:

Fig. 2. Boost inductor current for a half cycle of input voltage.

Fig. 3. AC voltage and current after power factor correction.

Fig. 4. LLC-SRC operating at key point A (V0 = 320V, and I0 = 3.57A).

Fig. 5. LLC-SRC operating at key point B (V0 = 360V, and I0 = 3.57A).

Fig. 6. LLC-SRC operating at key point C (V0 = 420V, and I0 = 3.57A).

Fig. 7. LLC-SRC operating at key point D (V0 = 420V, and I0 = 0.25A).

CONCLUSION:

In this paper, a 1.5 kW PEV battery charger with emphasis on the design of LLC-SRC for DC-DC stage of the battery charger is presented. A method for improvement in the power factor with boost converter is presented using hysteresis current control to keep line input voltage and current in phase using phase shift in inductor current. Simulation results show that the PFC stage achieves minimum THD as 0.07% and a power factor of 0.9976 having line current and voltage in phase. The LLC-SRC is designed to operate around resonance frequency to achieve maximum benefits of LLC converter, having minimum circulating energy, avoiding hard commutation of secondary rectifier diodes. Simulation results for the converter performance are presented which show that the turning off current of power switches have very low value throughout the charging process and is below 2.4A. Hence, the converter have minimum switching and conduction losses.

REFERENCES:

[1] H. Wang, S. Dusmez, and A. Khaligh, “A novel approach to design EV battery chargers using SEPIC PFC stage and optimal operating point tracking technique for LLC converter,” Applied Power Electronics Conference and Exposition (APEC), 2014 Twenty-Ninth Annual IEEE, pp.1683-1689, 16-20 March 2014.

[2] H. Wang, S. Dusmez, and A. Khaligh, “Design and Analysis of a Full-Bridge LLCBased PEV Charger Optimized for Wide Battery Voltage Range,” Vehicular Technology, IEEE Transactions on, Vol. 63, No. 4, pp.1603-1613, May 2014.

[3] J. Deng, S. Li, S. Hu, C.C. Mi, and R. Ma, “Design Methodology of LLC Resonant Converters for Electric Vehicle Battery Chargers,” Vehicular Technology, IEEE Transactions on, Vol. 63, No. 4, pp.1581-1592, May 2014.

[4] Marian K. Kazimierczuk, “Pulse-width Modulated DC-DC Power Converters,” Ohio, USA: John Wiley & Sons Ltd, pp. 129-134, 2008.

[5] H. Wang, and A. Khaligh, “Comprehensive Topological Analyses of Isolated Resonant Converters in PEV Battery Charging Applications,” Transportation Electrification Conference and Expo (ITEC), 2013 IEEE, pp.1-7, 16-19 June 2013.

Design of a New Combined Cascaded Multilevel Inverter Based on Developed H-Bridge with Reduced Number of IGBTs and DC Voltage Sources

ABSTRACT:

In this paper, a new combined cascaded multilevel inverter with reduced number of switches and DC voltage sources which is formed by series connection of same units with developed H-Bridge is proposed. For the purpose of generating all even and odd voltage levels 5 algorithms to determine the magnitudes of DC voltage sources is proposed. In order to investigate the advantages and disadvantages of the proposed combined cascaded multilevel inverter the proposed algorithms are compared to presented topologies from different points of view. The experimental results of the proposed topology are stated to check and verifying the performance of the proposed topology.

KEYWORDS:

  1. Multilevel inverter
  2. Cascaded multilevel inverter
  3. Combined topology
  4. Developed H-Bridge

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. Basic topology of proposed multilevel inverter.

EXPECTED SIMULATION RESULTS:

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

Fig. 2. Experimental results; (a) output voltage; (b) output voltage and current; (c) generated voltage levels by right side; (d) generated voltage levels by left side; (e) generated voltage levels by L,1 u ; (f) voltage across R2,2 S ; (g) voltage across 1 T ; (h) voltage across 3 T ; (i) voltage across a T .

CONCLUSION:

 In this paper, a new combined cascaded multilevel inverter has been proposed. After that, five different algorithms are proposed in order to determine the magnitudes of the DC voltage sources. By comparing these algorithms, it was concluded that the algorithm which generates a high number of voltage levels with less number of switches and DC voltage sources is better than other algorithms. According to this comparison, it was found that the fifth proposed algorithm is better among the proposed algorithms. In order to prove the claim about reduction of the number of IGBTs and DC voltage sources in the proposed topology, this topology was compared to presented topologies from different aspects. In these comparisons, it was found that the proposed topology generates 31 voltage levels with 14 IGBTs while presented topologies in [4], [10] and [12] generate the same number of voltage levels with 32, 16 and 34 IGBTs, respectively. Also, it was found that this number of voltage levels needs 4 DC voltage sources, whereas, the topologies which presented in [4] and [12] generate 17 and 9 voltage levels with the same number of DC voltage sources. Afterwards, correctness of performance of the proposed topology and relations have been verified through experimentation of the proposed topology with 2 input units in each side.

REFERENCES:

[1] C.I. Odeh, E.S. Obe, and O. Ojo,: “Topology for cascaded multilevel inverter,” IET Power Electron., vol. 9, no. 5, pp. 921-929, April 2016.

[2] E. Zamiri, N. Vosoughi, S.H. Hosseini, R. Barzegarkhoo, and M. Sabahi, “A new cascaded switched-capacitor multilevel inverter based on improved series–parallel conversion with less number of components,” IEEE Trans. Ind. Electron., vol. 63, no. 6, pp. 3582-3594, June 2016.

[3] N. Prabaharan and K. Palanisamy, “Analysis of cascaded H-bridge multilevel inverter configuration with double level circuit,” IET Power Electron., vol. 10, no. 9, pp. 1023-1033, July 2017.

[4] M.R. Banaei, M.R. Jannati Oskuee and H. Khounjahan, “Reconfiguration of semi-cascaded multilevel inverter to improve systems performance parameters,” IET Power Electron., vol. 7, no. 5, pp. 1106-1112, May 2014.

[5] E. Babaei, S. Laali, and Z. Bayat, “A single-phase cascaded multilevel inverter based on a new basic unit with reduced number of power switches,” IEEE Trans. Ind. Electron., vol. 62, no. 2, pp. 922-929, Feb. 2015.