Performance Evaluation of Seven Level Reduced Switch ANPC Inverter in Shunt Active Power Filter with RBFNN Based Harmonic Current Generation

ABSTRACT:

One of the serious issues that a Power System faces is the Power Quality (PQ) disturbance which occur mainly because of the non-linear loads. Among these PQ disturbances, harmonics play a vital role which should to be mitigated along with reactive power compensation. In this paper, a modified seven-level boost Active-Neutral-Point-Clamped (7LB-ANPC) inverter is utilized as a Shunt Active Power Filter (SAPF). Another vital aspect of this work is to retain the link voltage across the capacitor, which is accomplished through a PI controller tuned with an Adaptive Neuro-Fuzzy Inference System (ANFIS). An adaptive instantaneous p-q theory is instigated in the direction of extracting reference current and the harmonic extraction is carried out by using Radial Basis Function Neural Network (RBFNN). Gating sequence of inverter is generated for the outputs, which are attained from ANFIS and RBFNN and thus the opposite harmonics are injected to the Point of Common Coupling (PCC) by which current harmonics are eliminated with reactive power compensation. The 7Lb-ANPC inverter has a minimized number of switching devices with low switching losses and high boosting ability. By RBFNN based reference current generation, the source current THD of 0.89% is achieved. The proposed methodology is simulated through MATLAB and in hardware by utilizing FPGA Spartan 6E.

KEYWORDS:

1.      Power Quality

2.      Shunt Active Power Filter

3.      Multi-Level Inverters

4.      Active-Neutral-Point-Clamped Inverter

5.      Radial Basis Function Neural Network

6.      Adaptive Neuro-Fuzzy Inference System

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

 

 

Figure 1 Proposed Seven-Level ANPC Circuit Diagram

EXPECTED SIMULATION RESULTS:

Figure 2: Source Voltage waveform

 

Figure 3: Load Current waveform

Figure 4: Current injected at the PCC

  

Figure 5: Source Current

 

Figure 6: DC-link voltage

 

 

Figure 7: THD waveform with the RBFNN approach

Figure 8: THD waveform with PQ theory

 CONCLUSION:

In this paper, harmonic mitigation and reactive power compensation are accomplished through a modified seven-level boost ANPC inverter, which exhibits high boosting ability with a minimized number of switches and low switching losses. The reference current generation is highlighted through the adaptive instantaneous p-q theory with RBFNN. Link voltage in the capacitor is retained by using ANFIS and which is compared by the PI controller and Fuzzy. PWM generator with a hysteresis current controller has generated the required gating sequence for the modified 7LB-ANPC inverter. A detailed comparison of modified 7LB-ANPC with the recent strategies has been carried out. The simulation results has highlighted that the proposed methodology is well suited for harmonic mitigation.

REFERENCES:

[1] P. S. Harmonics, "Power System Harmonics: An Overview," in IEEE Transactions on Power Apparatus and Systems, vol. PAS-102, no. 8, pp. 2455-2460, Aug. 1983, doi: 10.1109/TPAS.1983.317745.

[2] M. Rastogi, R. Naik and N. Mohan, "A comparative evaluation of harmonic reduction techniques in three-phase utility interface of power electronic loads," in IEEE Transactions on Industry Applications, vol. 30, no. 5, pp. 1149-1155, Sept.-Oct. 1994, doi: 10.1109/28.315225.

[3] R. Arnold, "Solutions to the power quality problem," in Power Engineering Journal, vol. 15, no. 2, pp. 65-73, April 2001, doi: 10.1049/pe:20010202.

[4] D. Graovac, V. Katic and A. Rufer, "Power Quality Problems Compensation With Universal Power Quality Conditioning System," in IEEE Transactions on Power Delivery, vol. 22, no. 2, pp. 968-976, April 2007, doi: 10.1109/TPWRD.2006.883027.

[5] B. Singh, K. Al-Haddad and A. Chandra, "A review of active filters for power quality improvement," in IEEE Transactions on Industrial Electronics, vol. 46, no. 5, pp. 960-971, Oct. 1999, doi: 10.1109/41.793345.

 

Passivity-Based Control Strategy With Improved Robustness for Single-Phase Three-Level T-Type Rectifiers

ABSTRACT:

A passivity-based control (PBC) strategy with improved robustness for single-phase three-level rectifiers feeding resistive and constant power loads (CPLs) is proposed. It is shown that the control of the rectifier can be achieved if the damping injection is applied to the grid current only. In this case, the knowledge of load resistance is required in the computation of reference grid current amplitude. Since the output voltage and load current are dc quantities, the load resistance can be estimated easily. Then, the amplitude of the reference grid current is calculated from the power balance equation of the rectifier. The transfer function from reference grid current to actual grid current is derived. The derived transfer function is analyzed under variations in the filter inductance. The results reveal that the proposed PBC offers strong robustness to variations in the filter inductance when a suitable damping gain is selected. The performances of the proposed PBC strategy under undistorted and distorted grid voltage as well as, variations in inductor are investigated via experimental studies during steady-state and transients caused by the resistive load and CPL changes. In all cases, the output voltage is regulated at the desired value, and grid current tracks its reference.

KEYWORDS:

1.      Passivity-based control

2.      Damping injection

3.      Three-level T-type rectifier

4.      Constant power load

SOFTWARE: MATLAB/SIMULINK

 SCHEMATIC DIAGRAM:

 

Figure 1. Single-Phase Three-Level T-Type Rectifier Feeding Resistive Load And Cpl.

 EXPECTED SIMULATION RESULTS:

Figure 2. Waveforms Of Grid-Voltage (Eg), Grid Current (Ig) And Its Reference (I_ G ), Five-Level Voltage (Vxy ), Output Voltage (Vdc ) And Its Reference (V _ Dc ), And Capacitor Voltages (Vc1 And Vc2) Under Undistorted Grid Voltage.

Figure 3. Waveforms Of Grid-Voltage (Eg), Grid Current (Ig) And Its Reference (I_ G ), Output Voltage (Vdc ) And Its Reference (V _ Dc ), And Capacitor Voltages (Vc1 And Vc2) Under Distorted Grid Voltage.

Figure 4. Waveforms Of Grid-Voltage (Eg), Grid Current (Ig) And Its Reference (I_ G ), Output Voltage (Vdc ) And Its Reference (V _ Dc ), And Capacitor Voltages (Vc1 And Vc2) Under Rl D 25: (A) Le < L (Le D 1:6 Mh) And &1 D 1, (B) Le < L (Le D 1:6 Mh) And &1 D 20, (C) Le > L (Le D 2:4 Mh) And &1 D 20.

 

 

Figure 5. Waveforms Of Grid-Voltage (Eg), Grid Current (Ig) And Its Reference (I_ G ), Output Voltage (Vdc ) And Its Reference (V _ Dc ), Grid Current Error (X1), Output Voltage Error (X2), And Capacitor Voltages (Vc1 And Vc2) For A Step Change In &1 From 1 To 20 When Le D L.

 

Figure 6. Waveforms Of Grid-Voltage (Eg), Grid Current (Ig) And Its Reference (I_ G ), Output Voltage (Vdc ) And Its Reference (V _ Dc ), Resistive Load Current (Ir ), And Capacitor Voltages (Vc1 And Vc2) For A Step Change In V _ Dc From 250v To 300v Under Resistive Load R D 25.

Figure 7. Waveforms Of Grid-Voltage (Eg), Grid Current (Ig) And Its Reference (I_ G ), Output Voltage (Vdc ), Resistive Load Current (Ir ), Cpl Current (Icpl), Total Load Current (Il), And Capacitor Voltages (Vc1 And Vc2) For A Step Change In: (A) R From 100 To 50, (B) Cpl From 0.625kw To 1.25kw.

  

Figure 8. Waveforms Of Grid-Voltage (Eg), Grid Current (Ig) And Its Reference (I_ G ), Output Voltage (Vdc ) And Its Reference (V _ Dc ), Cpl Current (Icpl), And Capacitor Voltages (Vc1 And Vc2) For A Step Change In V _ Dc From 250v To 300v Under Cpl.

CONCLUSION:

This paper presented a robust PBC strategy for single-phase three-level T-type rectifiers feeding resistive and constant power loads. It is pointed out that both dc output voltage and grid current of the rectifier can be controlled if the damping injection is applied to the grid current only. It is shown that the proposed PBC strategy possesses strong robustness to variations in the inductance when the damping gain is selected in accordance with the grid current transfer function magnitude. The performance of the proposed PBC strategy is investigated by experimental studies during steady-state and transients caused by the load and reference voltage changes under undistorted and distorted grid voltage conditions and variations in inductance. It is shown that the dc output voltage is regulated at its reference value, and grid current tracks its reference in all conditions, particularly under constant power load, which may endanger the stability of the system due to the negative resistance characteristic.

REFERENCES:

[1] M. P. Kazmierkowski, L. G. Franquelo, J. Rodriguez, M. A. Perez, and J. I. Leon, ``High-performance motor drives,'' IEEE Ind. Electron. Mag., vol. 5, no. 3, pp. 6_26, Sep. 2011.

[2] S. Vazquez, S. M. Lukic, E. Galvan, L. G. Franquelo, and J. M. Carrasco, ``Energy storage systems for transport and grid applications,'' IEEE Trans. Ind. Electron., vol. 57, no. 12, pp. 3881_3895, Dec. 2010.

[3] F. Blaabjerg, M. Liserre, and K. Ma, ``Power electronics converters for wind turbine systems,'' IEEE Trans. Ind. Appl., vol. 48, no. 2, pp. 708_719, Mar./Apr. 2012.

[4] X. Liu, P. C. Loh, P. Wang, and F. Blaabjerg, ``A direct power conversion topology for grid integration of hybrid AC/DC energy resources,'' IEEE Trans. Ind. Electron., vol. 60, no. 12, pp. 5696_5707, Dec. 2013.

[5] G. Wang, G. Konstantinou, C. D. Townsend, J. Pou, S. Vazquez, G. D. Demetriades, and V. G. Agelidis, ``A review of power electronics for grid connection of utility-scale battery energy storage systems,'' IEEE Trans. Sustain. Energy, vol. 7, no. 4, pp. 1778_1790, Oct. 2016.

Non-Isolated DC-DC Power Converter With High Gain and Inverting Capability

ABSTRACT:

As the voltage gain of converter increases with the same ratio, the current gain also increases, this increase in current gains will affect the size of the input and the output capacitor. To reduce the ripple in the input current with simultaneous decreasing the input current ripple, a novel current fed interleaved high gain converter is proposed by utilizing the interleaved front-end structure and Cockcroft Walton (CW)-Voltage Multiplier (VM). The ``current fed'' term is used because, in proposed circuitry, all the capacitors of CW-VM are energized by a current path via inductors of the interleaved structure. The proposed converter can be applied as an input boost up the stage for low voltage battery energy storage systems, photovoltaic (PV) and fuel cell (FC) based DC-AC applications. The anticipated topology consists of the two low voltage rating switches. The main benefits of the anticipated converter configuration are the continuous (ripple free) input current, high voltage gain, reduced switch rating, high reliability, easy control structure and a high percentage of efficiency. The proposed converter's working principle, mathematical based steady state analysis, and detailed component design are discussed. The parasitic of the components has been considered in the analysis to show the deviation from the ideal cases. A detailed comparison with the other available converters is presented. The experimental results of the 300W prototype are developed to confirm the performance and functionality of the anticipated DC-DC converter.

KEYWORDS:

1.      Non-isolated

2.      Inverting

3.       Interleaved

4.      High gain

5.      Renewable

6.      Current fed

7.      Voltage multiplier

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

 Figure 1. Proposed Inverting High Gain Dc-Dc Converter.

EXPECTED SIMULATION RESULTS:

Figure 2. Input And Output: Voltage And Current Waveforms.

Figure 3. Inductor Voltages And Currents Waveforms.

Figure4. Input And Inductor Current Waveforms.

 

Figure 5. Switch Voltages And Input Current And Output Voltage Waveforms.

 

Figure 6. Switch Voltages, Input And Inductor Currents Waveforms.

 

Figure 7. Diode D1 And D2 Voltages And Inductor Currents Waveforms.

 

Figure 8. Capacitor Across Capacitor C1 And C2 Waveforms.

 

Figure 9. Voltage Difference Between Capacitors Waveforms.

 CONCLUSION:

A novel non-isolated current fed interleaved inverting high gain DC-DC power converter is reported for the renewable applications. The reported converter combines the feature of the interleaved fundamental boost converter & diode capacitor stages. The full-wave voltage multiplier arrangement is incorporated to raise the voltage gain by using a very minimal number of devices. At the same duty cycle, the proposed converter be able to easily extend to the greater numeral of stages to increase the gain by adding only 1 diode & 1 capacitor for each VM stage increment. The detailed operating modes for CCM & DCM are studied with the help of practical design criterion. The practical and the theoretical voltage gains at the same duty ratios has been validated and they are approximately equal. The detailed comparison with the recently proposed other converter has shown that the anticipated converter is further superior over the available converter topologies. The fabricated prototype is tested at 300W and observed conversion is efficiency 93.07% and presented experimental results to confirm the performance and theoretical analysis. The closed-loop control, integration with renewable energy systems, soft switching of semiconductors devices and voltage stress minimization of semiconductor devices are the future tasks of the proposed converter.

REFERENCES:

[2] Texas Instruments. TPS63700 Datasheet. (Jun. 2013). [Online]. Available: http://www.ti.com-/lit/ds/symlink/tps-63700.pdf

[3] S.-W. Hong, S.-H. Park, T.-H. Kong, and G.-H. Cho, ``Inverting buck-boost DC-DC converter for mobile AMOLED display using real-time self-tuned minimum power-loss tracking (MPLT) scheme with lossless soft-switching for discontinuous conduction mode,'' IEEE J. Solid-State Circuits, vol. 50, no. 10, pp. 2380_2393, Oct. 2015.

[4] M. Jabbari, ``Resonant inverting-buck converter,'' IET Power Electron., vol. 3, no. 4, pp. 571_577, Jul. 2010.

[5] Y. P. Siwakoti, F. Z. Peng, F. Blaabjerg, P. C. Loh, and G. E. Town, ``Impedance-source networks for electric power conversion Part I: A topological review,'' IEEE Trans. Power Electron., vol. 30, no. 2, pp. 699_716, Feb. 2015.

[6] T.-J. Liang, J.-H. Lee, S.-M. Chen, J.-F. Chen, and L.-S. Yang, ``Novel isolated high-step-up DC_DC converter with voltage lift,'' IEEE Trans. Ind. Electron., vol. 60, no. 4, pp. 1483_1491, Apr. 2013.

Multi-Mode Operation and Control of a Z-Source Virtual Synchronous Generator in PV Systems

 ABSTRACT:

The increasing penetration of power electronics-based distributed energy resources (DERs) displacing conventional synchronous generators is rapidly changing the dynamics of large-scale power systems. As the result, the electric grid loses inertia, voltage support, and oscillation damping needed to provide ancillary services such as frequency and voltage regulation. This paper presents the multi-mode operation of a Z-source virtual synchronous generator (ZVSG). The converter is a Z-source inverter capable of emulating the virtual inertia to increase its stability margin and track its frequency. The added inertia will protect the system by improving the rate of change of frequency. This converter is also capable of operating under normal and grid fault conditions while providing needed grid ancillary services. In normal operation mode, the ZVSG is working in MPPT mode where the maximum power generated from the PV panels is fed into the grid. During grid faults, a low voltage ride through control method is implemented where the system provides reactive power to reestablish the grid voltage based on the grid codes and requirements. The proposed system operation is successfully validated experimentally in the OPAL-RT real-time simulator.

KEYWORDS:

1.      Impedance-source inverter

2.      Virtual synchronous generator

3.      Photovoltaic (PV) systems

4.      Low voltage ride through

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

 

Figure 1. Proposed ZVSG Converter Equipped With VSG And LVRT Control Algorithms.

 EXPECTED SIMULATION RESULTS:

Figure 2. Rocof Curves With Different Amounts Of (A) Inertia (H) And (B) Damping Constant (Dp ).

 

Figure 3. Comparison In Zvsg Current Increase While (A) The Converter Is Directly Connecte (100(Ma)_3:2_10000 D 3200a) And (B) A Pre-Synchronizing Control Method Is Hired To Decrease The Current Increment (200(Ma)_1_5000 D 1000a).

 

Figure 4. Multi-Mode Operation Of The Zvsg During (A) Normal Operation (C) Voltage Sage Occurrence At T1 And Switching To Lvrt Mode And (D) Returning To Normal Mode At T2.

 CONCLUSION:

This paper studied the multi-mode operation of an impedance-source virtual synchronous generator which is comprised of a single-stage ZSI, equipped with VSG control algorithm and is capable of providing grid ancillary services. Since the PLL may fail to detect the correct angle in case of harmonic distorted voltage, a virtual flux orientation control method is hired which can select the correct angle to be fed to Park transformation. The operation of the system has been tested while transitioning from islanded to grid-connected mode where, to protect the system against inrush current while connecting to the grid, a pre-synchronizing control method is used to minimize the phase difference between grid and converter. In addition, a solution to survive the system against voltage faults is embedded in the system which can regulate the reactive power based on the grid codes. Hence, the control paradigm will switch from MPP generation to LVRT mode after detecting voltage sag in the system. In this method, the peak of the grid current is kept constant during LVRT operation mode and ensures over current protection limit is not violated then. The ZVSG has been implemented in the OPAL-RT real-time digital simulator and its validity have been verified by conducting several case studies. The proposed seamless control frame-work helps to smoothly switch between normal and faulty conditions.

REFERENCES:

[1] K. Jiang, H. Su, H. Lin, K. He, H. Zeng, and Y. Che, ``A practical secondary frequency control strategy for virtual synchronous generator,'' IEEE Trans. Smart Grid, vol. 11, no. 3, pp. 2734_2736, May 2020.

[2] K. Shi, W. Song, H. Ge, P. Xu, Y. Yang, and F. Blaabjerg, ``Transient analysis of microgrids with parallel synchronous generators and virtual synchronous generators,'' IEEE Trans. Energy Convers., vol. 35, no. 1, pp. 95_105, Mar. 2020.

[3] J. Chen and T. O'Donnell, ``Parameter constraints for virtual synchronous generator considering stability,'' IEEE Trans. Power Syst., vol. 34, no. 3, pp. 2479_2481, May 2019.

[4] H. Cheng, Z. Shuai, C. Shen, X. Liu, Z. Li, and Z. J. Shen, ``Transient angle stability of paralleled synchronous and virtual synchronous generators in islanded microgrids,'' IEEE Trans. Power Electron., vol. 35, no. 8, pp. 8751_8765, Aug. 2020.

[5] H. Nian and Y. Jiao, ``Improved virtual synchronous generator control of DFIG to ride-through symmetrical voltage fault,'' IEEE Trans. Energy Convers., vol. 35, no. 2, pp. 672_683, Jun. 2020.