A New Space Vector Pulse Width Modulated Transformer Less Single-Phase Unified Power Quality Conditioner

 ABSTRACT:

 

Emergence of solid-state switching devices, like thyristors, GTO’s, IGBT’s and etc, are widely used for controlling electric power in power electronic equipment for various purpose such as HVDC systems, computers etc. These devices draw disturbance in voltages and currents of both source side and distribution ends due to its non-linearity. This induce harmonics, reactive power, and excess neutral current cause the system to have less efficiency and reduction in power factor. In this paper transformer less single-phase unified power quality conditioner has been implemented to reduce the voltage and current distortions. The operation and control of single-phase transformer less three leg Unified power quality conditioner is investigated with the implementation of a new pulse width modulation method for solving the coupling problem introduced by common leg switches.

KEYWORDS:

1.      TL-UPQC

2.      SVPWM

3.      Harmonics

4.      Total harmonic distortion

5.      DSTACOM

  D   DVR

 

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

 

                                                  Fig. 1. Block Diagram for Harmonic Reduction Using UPQC.

EXPECTED SIMULATION RESULTS:

 

                                                          Fig. 2. DC- link Voltage Waveforms.

 

Fig. 3. Source Current Waveforms.

Fig. 4. % THD of Source Side Current.

 CONCLUSION:

The custom power devices such as DVR helps in compensation of voltage unbalances and DTATCOM helps in the elimination of current harmonics that are entering the circuit due to the presence of a non-linear load at the consumer side. By using a unified power quality conditioner both the issues such as compensation of voltage unbalances and elimination of current harmonics can be minimized. The replacement of the series transformer with a series inductance helps to overcome the issues of cost and weight of the system. The working principle and implementation of practical two-level space vector modulation has been shown. The special switching sequence incorporated in space vector modulation tech technique used here minimizes the coupling issues that occur in the common leg operation.

REFERENCES:

[1] A. Bendre, D. Divan, W. Kranz, W. Brumsickle, Equipment failures caused by power quality disturbances, in: Proc. IEEE IAS Annual Meeting, 2004, pp. 482– 489.

[2] I. Hunter, Power quality issues-a distribution company perspective, Power Eng. J., 15 (2) (Apr. 2001) 75–80.

[3] B. Singh, K. Al-Haddad, A. Chandra, A review of active filters for power quality improvement, IEEE Trans. Ind. Electron., 46 (5) (Oct. 1999) 960–971.

[4] P. Curtis, The fundamentals of power quality and their associated problems, IEEE Press, Wiley, 2007.

[5] M. El-Habrouk, M.K. Darwish, P. Mehta, Active power filters: a review, IEE Proc., Electr. Power Appl. 147 (5) (2000) 403, https://doi.org/10.1049/ipepa: 20000522.

Power quality enhancement in solar power with grid connected system using UPQC

 ABSTRACT:

 The need to generate pollution free energy has triggered the effect towards the usage of solar energy interconnection with the grid. Consequently, the Photovoltaic (PV) panel interfaced with the grid causes the power quality problems such as a voltage harmonics and voltage distortion etc., Active power filters are the powerful tool for mitigation of harmonics. This work involves the use of single-phase Unified Power Quality Conditioner (UPQC) based on a unit vector template control algorithm for its functions with grid integration of photovoltaic, such as voltage sags/ swell, unit power factor correction, voltage and current harmonic cancelation. The unit vector template control algorithm includes a phase-locked loop (PLL) mechanism that is responsible for avoiding multiple zero crossings during highly distorted grid voltage detection. A unit vector template control with a PLL-based control algorithm is applied to the shunt and series inverters of PV grid connected UPQC. In addition to normalizing voltage and current disturbances, the proposed controller has the functions of phase detection and perfect grid synchronization. It is proposed that the system performance is fully verified by MATLAB simulation with the response of load variation, transient response, THD, voltage swell and sag. The Total Harmonic Distortions (THDs) of proposed grid integration of photovoltaic systems through single-phase unified power quality conditioner (UPQC) obtain the range of IEEE standard.

KEYWORDS:

 

1.      Maximum power point tracking

2.      Phase locked loop

3.      Photovoltaic

4.      Grid tie inverter

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. Proposed UPQC with Solar Grid Connected System.

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Simulation result of PV.

Fig. 3. Output Voltage of Boost Converter.

Fig. 4. PV- Inverter Voltage Response.

Fig. 5. DC-Link Voltage of UPQC.

Fig. 6. Voltage Sag and swell compensation. 

 

Fig. 7. Source current.

Fig. 8. THD response Without UPQC system.

Fig. 9. THD response of Proposed System.

 

Fig. 10. Performance Comparison of MPPT.

CONCLUSION:

In this work presents, a single phase grid connected PV system. Although the system is designed to run smoothly on the unity power factor to enable efficient use of full inverter capacity, it runs on any desired power. Using the Perturb & Observe (P&O) algorithm to ensure MPPT performance, it can smoothly track changes in sunlight without oscillation. The simulation and test results show a very good match. The investigation will cover the MPPT technique, voltage control and current control of the system. The proposed unit vector template matching with UPQC gives the best results against all parameters, for example output of solar cell per unit is 0.94, steady state error 8%, and MPPT efficiency 96.56% and THD is 4.66%.In this study, UPQC developed a hysteresis controller based on a single phase UVTG approach and simulated three cases of voltage sag/swell, unity power factor correction, voltage and current synchronization. The Total Harmonic Distortions (THDs) of proposed grid integration of photovoltaic systemsalong with single-phase unified power quality conditioner (UPQC) obtain the range of IEEE standard because the THD is less than 5%.

Declaration of Competing Interest

The outcomes demonstrate that proposed unit vector template matching with UPQC gives the best results against all parameters, for example output of each solar cell per unit is 0.94, steady state error 8%, and MPPT efficiency 94.92% and THD is 4.66%. In this study, UPQC developed a hysteresis controller based on a single phase UVTG approach and simulated three cases of voltage sag/swell, unity power factor correction, voltage and current synchronization. Simulation results show satisfactory behavior in steady state, and dynamic conditions such as load variation in sunlight, voltage sags, swell and THD. The Total

Harmonic Distortions (THDs) of proposed grid integration of photovoltaic systems through single-phase unified power quality conditioner (UPQC) found within limits of the IEEE standard because the THD is less than 5%.

REFERENCES:

[1] S. Kr. Tiwari, B. Singh, P.K. Goel, Design and control of micro-grid fed by renewable energy generating sources, IEEE Trans. Ind. Appl. (2018) 1, https://doi. org/10.1109/TIA.2018.2793213, 1.

[2] Z. Zaheeruddin, M. Manas, Renewable energy management through microgrid central controller design: an approach to integrate solar, wind and biomass with battery, Energy Rep. 1 (2015) 156–163, https://doi.org/10.1016/j. egyr.2015.06.003.

[3] Y.V. Pavan Kumar, B. Ravikumar, Renewable energy based micro grid system sizing and energy management for green buildings, J. Mod. Power Syst. Clean Energy 3 (March 1) (2015) 1. -1.

[4] G. Rizzo, Automotive applications of solar energy, IFAC Proceed. Vol. 43 (July 7) (2010) 174–185.

[5] R. OctaPratama, M. Effendy, Z. Has, Optimization maximum power point tracking (MPPT) using P&O-fuzzy and IC-fuzzy in photovoltaic, Kinetik 3 (2018), https:// doi.org/10.22219/kinetik.v3i2.200.

Power Quality Assessment of Voltage Positive Feedback Based Islanding Detection Algori

 ABSTRACT:

 

Islanding refers to a condition where distributed generators (DGs) inject power solely to the local load after electrical separation from power grid. Several islanding detection methods (IDMs) categorized into remote, active, and passive groups have been reported to detect this undesirable state. In active techniques, a disturbance is injected into the DG’s controller to drift a local yardstick out of the permissible range. Although this disturbance leads to more effective detections even in well-balanced island, it raises the total harmonic distortion (THD) of the output current under the normal operation conditions. This paper analyzes the power quality aspect of the modified sliding mode controller as a new active IDM for grid-connected photovoltaic system (GCPVS) with a string inverter. Its performance is compared with the voltage positive feedback (VPF) method, a well-known active IDM. This evaluation is carried out for a 1 kWp GCPVS in MATLAB/Simulink platform by measuring the output current harmonics and THD as well as the efficiency under various penetration and disturbance levels. The output results demonstrate that since the proposed disturbance changes the amplitude of the output current, it does not generate harmonics/subharmonics. Thereby, it has a negligible adverse effect on power quality. It is finally concluded that the performance of the sliding mode-based IDM is reliable from the standpoints of islanding detection and power quality.

KEYWORDS:

1.      Islanding detection method (IDM)

2.      Power quality

3.      Sliding mode controller

4.       Total harmonic distortion (THD)

5.      Voltage positive feedback (VPF)

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

 

Fig. 1. Schematic of case study system under evaluation.

 EXPECTED SIMULATION RESULTS:

 

 

Fig. 2. Effect of VPF and proposed schemes on THDI with different percentages

of nominal power.

 

 Fig. 3. Effect of classic VPF and proposed IDM on power quality (harmonic spectra).

 

Fig. 4. Average THDI for different disturbance sizes. (a) Modified sliding

mode. (b) Classic VPF.

 CONCLUSION:

In this paper, the influence of the classic VPF and modified sliding-mode IDM on the GCPVS’s power quality and efficiency has been evaluated. The study has been done for a 1 kWp PV system with string inverter. The simulation results show that, while the THD of output current in the proposed IDM is smaller than the simple VPF, both methods render acceptable power quality in a wide range of system operation. This proper performance has been achieved due to the variation of the current magnitude rather than the angle or frequency. This magnitude variation is realized in VPF and the proposed method in the current and voltage control loops (MPPT), respectively. The simulations also confirm that the acceptable THDI and harmonics are guaranteed in multi-GCPVSs connection situation even at low power generation levels as the worst scenario. Since the new technique tries to deviate the system from its MPP condition, the effect of embedded disturbance on the efficiency is also performed. In this regard, the simulations are carried out and a negligible reduction in MPPT and inverter efficiencies (less than 0.04%) has been demonstrated in the proposed method. This occurs since MPP can be gained at a small bound around ref. It has been finally concluded that the modified slidingmode controller has the advantages of the conventional VPF scheme in islanding detection as well as a higher power quality in the production of energy.

REFERENCES:

[1] A. Jäger-Waldau, “PV status report 2017,” Publications Office of the European Union, Luxembourg, 2018.

[2] M. Sandhu and T. Thakur, “Harmonic minimization in a modified cascaded multilevel inverter for islanded microgrid using two switching techniques,” International Journal of Grid and Distributed Computing, vol. 10, no. 12, pp. 11-20, Dec. 2017.

[3] S. Natarajan and R. S. R. Babu, “Reduction of total harmonic distortion in cascaded H-bridge inverter by pattern search technique,” International Journal of Electrical and Computer Engineering (IJECE), vol. 7, no. 6, p. 3292, Dec. 2017.

[4] A. Luo, Q. Xu, F. Ma et al., “Overview of power quality analysis and control technology for the smart grid,” Journal of Modern Power Systems and Clean Energy, vol. 4, no. 1, pp. 1-9, Jan. 2016.

[5] A. Khamis, H. Shareef, E. Bizkevelci et al., “A review of islanding detection techniques for renewable distributed generation systems,” Renewable and Sustainable Energy Reviews, vol. 28, pp. 483-493, Dec. 2013.

Hybrid converter topology for reducing torque ripple of BLDC motor

 ABSTRACT:

 This study investigates the torque ripple performance of brushless DC (BLDC) motor drive system by integrating both modified single-ended primary inductor converter (SEPIC) and silicon carbide metal–oxide–semiconductor field-effect transistor based three-level neutral-point-clamped (NPC) inverter. In BLDC motor, the high commutation torque ripple is an important origin of vibration, speed ripple and prevents the use of the BLDC motor drive system in high-performance and high-precision applications. For torque ripple reduction, the modified SEPIC converter is employed at the entrance of the three-level NPC inverter, which regulates the DC-link voltage according to the motor speed. Moreover, the three-level NPC inverter is employed as a second-stage converter to suppress current ripple for further torque ripple reduction. Finally, the performance of the proposed hybrid converter topology is verified by simulation and laboratory experimental results.

KEYWORDS:

1.      DSP controller

2.      Energy eficiency

3.      Fuzzy logic (FL)

4.      MPPT

5.      Photovoltaic systems

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

 

                         Fig. 1 BLDC motor drive system with modified SEPIC converter and three-level NPC inverter

(a) Proposed converter topology

 BLOCK DIAGRAM:

                                                             Fig. 2 BLDC motor drive control strategy

(a) Block diagram of PWM controller for three-level NPC inverter

 

EXPECTED SIMULATION RESULTS:

Fig. 3 Continued

Fig. 4 Phase current and torque waveforms

(a) Phase current and torque waveforms from simulation at 2500 rpm and 0.825 N m, (b) Phase current and torque waveforms from simulation at 2500 rpm and 0.825 N m, (c) Phase current and torque waveforms from simulation at 6000 rpm and 0.825 N m, (d) Phase current and torque waveforms from simulation at 6000 rpm and 0.825 N m

CONCLUSION:

A novel hybrid circuit topology has been proposed in this paper which is built by a modified SEPIC converter and a SiC-MOSFETbased three-level NPC converter for minimising torque ripple in a BLDC motor drive system. For efficient reduction of torque ripple, the first stage is the modified SEPIC converter that lifts the DClink voltage to the desired value based on the motor speed measurement. For further torque ripple reduction, the three-level NPC inverter is employed as the second-stage converter to suppress current ripple. Experimental results show that the proposed hybrid converter topology can suppress the torque ripple to 14.6% at the speed of 6000 rpm, commutation torque ripple is reduced substantially and produce smooth torque waveform than the BLDC motor driven by the two-level, three-level NPC, twolevel inverter with DC-link voltage control, and two-level inverter with SEPIC converter and switch selection circuit topologies.

REFERENCES:

[1] Singh, B., Bist, V.: ‘An improved power quality bridgeless Cuk converter fed BLDC motor drive for air conditioning system’, IET Power Electron., 2013, 6, (5), pp. 902–913

[2] Carlson, R., Lajoie-Mazenc, M., Fagundes, J.C.D.S.: ‘Analysis of torque ripple due to phase commutation in brushless dc machines’, IEEE Trans. Ind. Appl., 1992, 28, (3), pp. 632–638

[3] Lee, S.K., Kang, G.H., Hur, J., et al.: ‘Stator and rotor shape designs of interior permanent magnet type brushless DC motor for reducing torque fluctuation’, IEEE Trans. Magn., 2012, 48, pp. 4662–4665

[4] Seo, U.J., Chun, Y.D., Choi, J.H., et al.: ‘A technique of torque ripple reduction in interior permanent magnet synchronous motor’, IEEE Trans. Magn., 2011, 47, (10), pp. 3240–3243

[5] Murai, Y., Kawase, K., Ohashi, K., et al.: ‘Torque ripple improvement for brushless DC miniature motors’, IEEE Trans. Ind. Appl., 1989, 25, (3), pp. 441–450

Voltage Sag Enhancement of Grid Connected Hybrid PV-Wind Power System Using Battery and SMES Based Dynamic Voltage Restorer

 ABSTRACT:

 Renewable energy sources; which are abundant in nature and climate friendly are the only preferable choice of the world to provide green energy. The limitation of most renewable energy sources specifically wind and solar PV is its intermittent nature which are depend on wind speed and solar irradiance respectively and this leads to power fluctuations. To compensate and protect sensitive loads from being affected by the power distribution side fluctuations and faults, dynamic voltage restorer (DVR) is commonly used. This research work attempts to withstand and secure the effect of voltage fluctuation of grid connected hybrid PV-wind power system. To do so battery and super magnetic energy storage (SMES) based DVR is used as a compensating device in case of voltage sag condition. The compensation method used is a pre-sag compensation which locks the instantaneous real time three phase voltage magnitude and angle in normal condition at the point of common coupling (PCC) and stores independently so that during a disturbance it used for compensation. Symmetrical and asymmetrical voltage sags scenario are considered and compensation is carried out using Power System Computer Aided Design or Electro Magnetic Transient Design and Control (PSCAD/EMTDC) software.

KEYWORDS:

1.      Dynamic voltage restorer (DVR)

2.      energy storage

3.      intermittent

4.      power quality

5.      voltage sag compensation

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

FIGURE 1. On grid PV-wind hybrid system

EXPECTED SIMULATION RESULTS:

 

                                                                                   (a)

(b)

(c)

FIGURE 2. Simulation results and DVR response for 25% symmetrical voltage sag case (a) load voltage without DVR, (b) DVR injected voltage and (c) load voltage with DVR

 

(a)

(b)

(c)

FIGURE 3. Simulation results and DVR response for 12% symmetrical voltage sag case (a) load voltage without DVR, (b) DVR injected voltage and (c) load voltage with DVR

(a)

(b)

(c)

FIGURE 4. Simulation results and DVR response for 25% asymmetrical voltage sag case (a) load voltage without DVR, (b) DVR injected voltage and (c) load voltage with DVR

(a)

(b)

(c)

FIGURE 5. Simulation results and DVR response for 35% asymmetrical voltage sag case (a) load voltage without DVR, (b) DVR injected voltage and (c) load voltage with DVR

 

CONCLUSION:

In this paper, a voltage sag enhancement of sensitive load which gets power from grid connected PV-wind power system is demonstrated using HES based DVR. The proposed DVR targets to protect the sensitive load from affected by any voltage fluctuation which arise either from fault condition or unstable power output of PV-wind system. The control and operations of BES and SMES devices is developed by observing voltage condition of the grid at the PCC and the SOC levels of battery and SMES. In addition to this, for full realization of the proposed DVR system the control and operation of the VSC is developed by observing the voltage level at the PCC. The pre-sag compensation strategy is selected based on the capability of both magnitude and phase jump restoration. Based on the conditions, three operating states of the HES based DVR are defined, which are normal (idle state), charging state and discharging state. The effectiveness of the proposed operating states has been demonstrated in realistic cases. In the simulation, different voltage sag depth scenarios are considered for both symmetrical and asymmetrical voltage imbalances and the HES based DVR works well. A combination of voltage sag, voltage swell and harmonics scenarios will be demonstrated in the future works.

REFERENCES:

[1] BP Statistical Review of World Energy, 68th ed. 2019.

[2] M. R. Banaei and S. H. Hosseini, “Verification of a new energy control strategy for dynamic voltage restorer by simulation,” vol. 14, pp. 112–125, 2006.

[3] IRENA, Future of wind: Deployment, investment, technology, grid integration and socio-economic aspects (A Global Energy Transformation paper). International Renewable Energy Agency, Abu Dhabi, 2019.

[4] IRENA, Future of Solar Photovoltaic: Deployment, investment, technology, grid integration and socio-economic aspects (A Global Energy Transformation: paper). International Renewable Energy Agency, Abu Dhabi, 2019.

[5] H. M. Al-masri, S. Member, M. Ehsani, and L. Fellow, “Feasibility Investigation of a Hybrid On-Grid Wind Photovoltaic Retrofitting System,” IEEE Trans. Ind. Appl., vol. 52, no. 3, pp. 1979–1988, 2016.