Constant Power Generation Using Modified MPPT P&O to Overcome Overvoltage on Solar Power Plants

ABSTRACT:

Indonesia is a tropical country that has the privilege of gaining sunshine year-round so that the utilization of solar energy as a solar power plant can be a potential power plant to be developed. One of the problems in the solar power plant system is the power instability generated by the solar panels because it relies heavily on irradiance and relatively low energy conversion efficiency. To solve this problem, the Maximum control of Power Point Tracking (MPPT) is required by the Perturb and Observe (P&O) methods. This P&O MPPT control makes solar PV operate at the MPP point so that the solar PV output power is maximized. However, the MPPT P&O control that works at the MPP point makes the output voltage to the load is also maximum that causes overvoltage. This paper, therefore, discusses the modification of the MPPT Perturb and Observe (P&O) algorithm for Constant Power Generation (CPG) that combines MPPT P&O with the power control settings to the maximum limit of solar PV. This method can set up 2 operating conditions of the solar PV namely MPPT mode and CPG mode. The MPPT mode works when the solar PV output power is smaller than the reference power to maximize solar PV output power. However when the solar PV output power is more than or equal to the reference power then the CPG mode works to limit the solar panel's output power. Based on the simulated results of this MPPT-CPG control shows the load output voltage  response can be kept constant 48 V with less than 5% error that has been verified using a variety of irradiance and reference power.

KEYWORDS:

1.      Constant power generation (CPG)

2.      Maximum power point tracking (MPPT) P&O

3.      Solar PV

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, we propose the MPPT P&O-CPG method to be able to control solar panels that work on 2 conditions i.e. in MPPT operations and CPG operations to avoid overvoltage on the load. This MPPT P&O-CPG method has been evaluated through a PSIM simulation. Simulated results indicate that the MPPT mode is identified when the load requirements are greater or equal to the solar power panel (PPV < = Pref) and the voltage on the output side of the < 48V. While CPG mode is identified when the power requirements of the solar panel are greater than the load power (PPV > Pref) and the voltage at > 48V output. The performance of the MPPT P&O-CPG method is proven to avoid excess voltage with a control error limit of ± 5% of the rating voltage on the load although it is still overshot during mode switching due to irradiance fluctuations.

REFERENCES:

[1] M. Hassani, S. Mekhilef, A. Patrick Hu, and N. R. Watson, "A novel MPPT algorithm for load protection based on output sensing control," IEEE Ninth International Conference on Power Electronics and Drive Systems (PEDS), pp. 1120-1124, 2011.

[2] T. Esram, and P. L. Chapman, "Comparison of photovoltaic array maximum power point tracking techniques," IEEE Transactions on Energy Conversion, vol. 22, no. 2, pp. 439-449, June 2007.

[3] D. Beriber, and A. Talha, "MPPT techniques for PV systems," 4^th International Conference on Power Engineering, Energy and Electrical Drives, pp. 1437-1442, 2013.

[4] N. Moubayed, A. El-Ali, and R. Outbib, “Comparison of two MPPT techniques for PV system,” WSEAS Trans Environ Dev, 2009.

[5] E. Prasetyono, D. O. Anggriawan, A. Z. Firmansyah, and N. A. Windarko, "A modified MPPT algorithm using incremental conductance for constant power generation of photovoltaic systems," Engineering  Technology and Applications (IES-ETA) International ElectronicsSymposium on, pp. 1-6, 2017.

Artificial Neural Network for Control and Grid Integration of Residential Solar Photovoltaic Systems

ABSTRACT:  

Residential solar photovoltaic (PV) energy is becoming an increasingly important part of the world's renewable energy. A residential solar PV array is usually connected to the distribution grid through a single-phase inverter. Control of the single-phase PV system should maximize the power output from the PV array while ensuring overall system performance, safety, reliability, and controllability for interface with the electricity grid. This paper has two main objectives. The first objective is to develop an artificial neural network (ANN) vector control strategy for a LCL-filter based single-phase solar inverter. The ANN controller is trained to implement optimal control, based on approximate dynamic programming. The second objective is to evaluate the performance of the ANN-based solar PV system by (a) simulating the PV system behavior for grid integration and maximum power extraction from solar PV array in a realistic residential PV application and (b) building an experimental solar PV system for hardware validation. The results demonstrate that a residential PV system using the ANN control outperforms the PV system using the conventional standard vector control method and proportional resonant control method in both simulation and hardware implementation. This is also true in the presence of noise, disturbance, distortion, and non-ideal conditions.

KEYWORDS:

1.      Artificial neural networks

2.      DC-AC power converters

3.      DC-DC power converters

4.      Dynamic programming

5.      Maximum power point tracker

6.      Optimal control

7.      Solar power generation

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This paper proposes a single-phase, residential solar PV system based on artificial neural networks and adaptive dynamic programming for MPPT control and grid integration of a solar photovoltaic array through an LCL-filter based inverter. The proposed artificial neural network controller implements the optimal control based on the approximate dynamic programming. Both the simulation and hardware experiment results demonstrate that the solar PV system using the ADP-based artificial neural network controller has more improved performance than that using the proportional resonant or conventional standard vector control techniques, such as no requirement for damping resistance, more reliable and efficient extraction of solar power, more stable DC-link voltage, and more reliable integration with the utility grid. Using the ADP-based neural network control technique, the harmonics are significantly reduced and the system shows much stronger adaptive ability under uncertain conditions, which would greatly benefit the integration of small-scale residential solar photovoltaic systems into the grid.

REFERENCES:

[1] Renewable Energy World Editors. (2014, Nov. 12). Residential Solar Energy Storage Market Could Approach 1 GW by 2018.  Available:http://www.renewableenergyworld.com.

[2] R. A. Mastromauro, M. Liserre and A. D. Aquila, “Control Issues in Single-Stage Photovoltaic Systems: MPPT, Current and Voltage Control”, IEEE Trans. Ind. Informatics, vol. 8, no. 2, pp. 241-254, May 2012.

[3] E. Lorenzo, G. Araujo, A. Cuevas, M. Egido, J. Miñano and R. Zilles, Solar Electricity: Engineering of Photovoltaic Systems, Progensa, Sevilla, Spain, 1994.

[4] J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galván, R. C. P. Guisado, M. Á. M. Prats, J. I. León, and N. Moreno-Alfonso, “Power- Electronic Systems for the Grid Integration of Renewable Energy Sources: A Survey”, IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1002-1016, August 2006.

[5] W. T. Franke, C. Kürtz and F. W. Fuchs, "Analysis of control strategies for a 3 phase 4 wire topology for transformerless solar inverters," inProc. IEEE Int. Symp. Ind. Electron., Bari, pp. 658-663, 2010.

Application of Boost Converter to Increase the Speed Range of Dual-stator Winding Induction Generator in Wind Power Systems

 ABSTRACT:

 In this paper, a topology using a Dual-stator Winding Induction Generator (DWIG) and a boost converter is proposed for the variable speed wind power application. At low rotor speeds, the generator saturation limits the voltage of the DWIG. Using a boost converter, higher DC voltage can be produced while the DWIG operates at Maximum Power Point Tracking (MPPT) even at low speed and low voltage conditions. Semiconductor Excitation Controller (SEC) of the DWIG utilizes Control-Winding Voltage Oriented Control (CWVOC) method to adjust the voltage, considering V/f characteristics. For the proposed topology, the SEC capacity and the excitation capacitor is optimized by analyzing the SEC reactive current considering wind turbine power-speed curve, V/f strategy, and the generator parameters. The method shows that the per-unit capacity of the SEC can be limited to the inverse of DWIG magnetizing reactance per-unit value. The topology is simulated in MATLAB/Simulink platform and experimented with a scaled 1 kW prototype. Both simulation and experimental results demonstrate wide variable speed operation range of the DWIG and verify the optimization.

KEYWORDS:

1.      Boost converter

2.      Control-winding voltage oriented control

3.      Dual-stator winding induction generator (DWIG)

4.      Wind power

5.      Variable speed operation.

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This paper proposes a topology for variable speed wind power application using dual stator-winding induction generator. A boost converter is utilized for MPPT and wide range variable speed operation, especially at low-speed condition is obtained. At low speeds, DWIG voltage is dropped due to V/f strategy and a boost converter is used to increase the voltage level to meet the higher and constant voltage requirement, such as in voltage source converter DC-link or offshore DC network applications. In the proposed topology, by choosing the optimum excitation capacitor, the capacity of the semiconductor excitation controller is minimized. Finally, to verify the proper operation of the proposed system, simulation and experimental results are presented which validate the wide-speed range operation of the system and the excitation capacitor optimization method.

REFERENCES:

[1] REN21, “Renewables 2016: Global status report,” 2016. [Online]. Available: http://www.ren21.net.

[2] F. Blaabjerg and K. Ma, "Future on Power Electronics for Wind Turbine Systems," IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 1, no. 3, pp. 139-152, Sept. 2013.

[3] Z. Chen, J. M. Guerrero, and F. Blaabjerg, "A Review of the State of the Art of Power Electronics for Wind Turbines," IEEE Transactions on Power Electronics, vol. 24, no. 8, pp. 1859-1875, Aug. 2009.

[4] V. Yaramasu, B. Wu, P. C. Sen, S. Kouro and M. Narimani, "High-power wind energy conversion systems: State-of-the-art and emerging technologies," Proceedings of the IEEE, vol. 103, no. 5, pp. 740-788, May 2015.

[5] H. Nian and Y. Song, "Direct Power Control of Doubly Fed Induction Generator Under Distorted Grid Voltage," IEEE Transactions on Power Electronics, vol. 29, no. 2, pp. 894-905, Feb. 2014.

 

An Improved Grid Current and DC Capacitor Voltage Balancing Method for Three-Terminal Hybrid AC/DC Microgrid

 ABSTRACT:

 In this paper, a three-terminal AC/DC hybrid microgrid with two DC terminals and one AC terminal is proposed. The proposed system consists of cascaded H-bridge (CHB) converters based AC grid interface and two dual active bridge (DAB) converters based DC subgrid interface that connects two isolated DC buses. In order to reduce the number of power conversion stages and power devices, the DAB converters are directly connected to CHB DC rails according to the system operation requirement. To overcome the imbalanced grid currents and DC rail voltages issues caused by this modified system configuration with only two power conversion stages, an improved method is proposed through the zero-sequence voltage injection in the CHB converters. In addition, to avoid the conflicts between zero-sequence voltage injection and the voltage/current regulation of the system, the impacts of the control parameters to the system stability and dynamic response are investigated. Evaluation results from both three-terminal and five-terminal hybrid AC/DC microgrids show that the generalized effectiveness of the proposed three-phase AC current and DC rail voltage balancing method.

KEYWORDS:

1.      Three-terminal microgrid

2.      Hybrid AC/DC microgrid

3.      Zero-sequence voltage injection

4.      Current balancing control

5.      Voltage balancing control

6.      Grid-voltage sags

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a multi-terminal hybrid AC/DC microgrid structure with two power conversion stages is described in detail and a three-terminal hybrid microgrid with two DC ports is mainly selected for case study. In order to solve the issues of DC capacitor voltages and three-phase grid currents unbalance caused by mismatched DC power between DC ports, an improved control method through the adoption of zero-sequence voltage injection is developed. It has been extensively verified that the grid current and CHB capacitor voltage balancing control can be achieved simultaneously even in the severe case with highly mismatched DC power, grid-voltage sags, or the changes of connection between AC and DC subgrids.

REFERENCES:

[1] P. Ch. Loh, D. Li, Y. K. Chai, and F. Blaabjerg, “Autonomous operation of hybrid microgrid with AC and DC subgrids,” IEEE Trans. Power Electron., vol. 28, no. 5, pp. 2214–2223, May. 2013.

[2] P. Ch. Loh, D. Li, Y. K. Chai, and F. Blaabjerg, “Autonomous control of interlinking converter with energy storage in hybrid AC–DC microgrid,” IEEE Trans. Ind. Appl., vol. 49, no. 3, pp. 1374–1383, May. 2013.

[3] Y. W. Li, D. M. Vilathgamuwa, and P. C. Loh, “Design, analysis and real-time testing of controllers for multi-bus microgrid system,” IEEE Trans. Power Electron., vol. 19, no. 5, pp. 1195–1204, Sep. 2004.

[4] J. M. Guerrero, J. C. Vasquez, J. Matas, L. G. de Vicuna, and M. Castilla, “Hierarchical control of droop-controlled AC and DC microgrids—Ageneral approach toward standardization,” IEEE Trans. Ind. Electron.,vol. 58, no. 1, pp. 158–172, Jan. 2011.

[5] K. T. Tan, X. Y. Peng, P. L. So, Y. C. Chu, and M. Z. Q. Chen, “Centralized control for parallel operation of distributed generation inverters in microgrids,” IEEE Trans. Smart Grid, vol. 3, no. 4, pp. 1977–1987, Dec.2012.

 

 

An Integrated Hybrid Power Supply for Distributed Generation Applications Fed by Nonconventional Energy Sources

 ABSTRACT:

A new, hybrid integrated topology, fed by photovoltaic (PV) and fuel cell (FC) sources and suitable for distributed generation applications, is proposed. It works as an uninterruptible power source that is able to feed a certain minimum amount of power into the grid under all conditions. PV is used as the primary source of power operating near maximum power point (MPP), with the FC section (block), acting as a current source, feeding only the deficit power. The unique “integrated” approach obviates the need for dedicated communication between the two sources for coordination and eliminates the use of a separate, conventional dc/dc boost converter stage required for PV power processing, resulting in a reduction of the number of devices, components, and sensors. Presence of the FC source in parallel (with the PV source) improves the quality of power fed into the grid by minimizing the voltage dips in the PV output. Another desirable feature is that even a small amount of PV power (e.g., during low insolation), can be fed into the grid. On the other hand, excess power is diverted for auxiliary functions like electrolysis, resulting in an optimal use of the energy sources. The other advantages of the proposed system include low cost, compact structure, and high reliability, which render the system suitable for modular assemblies and “plug-n-play” type applications. All the analytical, simulation, and experimental results of this research are presented.

KEYWORDS:

1.      Buck-boost

2.      Distributed generation

3.       Fuel cell

4.      Grid-connected

5.      Hybrid

6.       Maximum power point tracking (MPPT)

7.      Photovoltaic

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

A compact topology, suitable for grid-connected applications has been proposed. Its working principle, analysis, and design procedure have been presented. The topology is fed by a hybrid combination of PV and FC sources. PV is the main source, while FC serves as an auxiliary source to compensate for the uncertainties of the PV source. The presence of FC source improves the quality of power (grid current THD, grid voltage profile, etc.) fed into the grid and decreases the time taken to reach the MPP. Table IV compares the system performance with and without the FC block in the system. A good feature of the proposed configuration is that the PV source is directly coupled with the inverter (and not through a dedicated dc–dc converter) and the FC block acts as a current source. Considering that the FC is not a stiff dc source, this facilitates PV operation at MPP over a wide range of solar insolation, leading to an optimal utilization of the energy sources. The efficiency of the proposed system in mode-1 is higher (around 85% to 90%) than mode 2 and 3 (around 80% to 85%). A laboratory prototype of the proposed system has shown encouraging results in terms of efficiency, complexity, reliability, EMI concerns, and other features. Table V compares the proposed system and some of the existing HDGS configurations with respect to various parameters and features.

REFERENCES:

[1] J. Kabouris and G. C. Contaxis, “Optimum expansion planning of an unconventional generation system operating in parallel with a large scale network,” IEEE Trans. Energy Convers., vol. 6, no. 3, pp. 394–400, Sep. 1991.

[2] P. Chiradeja and R. Ramakumar, “An approach to quantify the technical benefits of distributed generation,” IEEE Trans. Energy Convers., vol. 19, no. 4, pp. 764–773, Dec. 2004.

[3] Y. H. Kim and S. S. Kim, “An electrical modeling and fuzzy logic control of a fuel cell generation system,” IEEE Trans. Energy Convers., vol. 14, no. 2, pp. 239–244, Jun. 1999.

[4] K. N. Reddy and V. Agarwal, “Utility interactive hybrid distributed generation scheme with compensation feature,” IEEE Trans. Energy Convers., vol. 22, no. 3, pp. 666–673, Sep. 2007.

[5] K. S. Tam and S. Rahman, “System performance improvement provided by a power conditioning subsystem for central station photovoltaic fuel cell power plant,” IEEE Trans. Energy Convers., vol. 3, no. 1, pp. 64–70.

 

An Effective Voltage Controller for Quasi-Z-Source Inverter-Based STATCOM With Constant DC-Link Voltage

 ABSTRACT:

A quasi-Z-source inverter (qZSI) could achieve buck/boost conversion as well as dc to ac inversion in a single-stage topology, which reduces the structure cost when compared to a traditional two-stage inverter. Specifically, the buck/boost conversion was accomplished via shoot-through state which took place across all phase legs of the inverter. In this paper, instead of using traditional dual-loop-based proportional integral (PI)-P controller, a type 2 based closed-loop voltage controller with novel dc-link voltage reference algorithm was proposed to fulfill the dc-link voltage tracking control of a single-phase qZSI regardless of any loading conditions, without the need of inner inductor current loop. A dc–ac boost inverter with similar circuit parameters as a Qzsi was used to verify the flexibility of the proposed controller. The dynamic and transient performances of the proposed controller were investigated to evaluate its superiority against the aforementioned conventional controller. The integrated proposed controller and qZSI topology was then employed in static synchronous compensator application to perform reactive power compensation at the point of common coupling. The effectiveness of the proposed approach was verified through both simulation and experimental studies.

KEYWORDS:

1.      Control system analysis

2.      Flexible ac transmission systems

3.      Quasi-Z-source inverter (qZSI)

4.      Reactive power control

5.      Static volt-ampere reactive (VAR) compensators.

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

A voltage controller based on type 2 compensator incorporating a novel dc-link voltage reference algorithm was proposed for single-phase dc–ac boost inverter and qZSI topologies. When compared with the traditional dual-loop-based PI-P controller, the proposed controller showed simpler design procedures to attain its control parameters without using trial and error method. In addition, the proposed controller demonstrated stability and excellent dynamic and transient performances even though Qzsi was operating in discontinuous conduction mode. Furthermore, constant qZSI dc-link voltage was achieved by the proposed dc-link voltage reference algorithm regardless of any loading conditions. The proposed qZSI was employed in STATCOM application to perform reactive power compensation at the PCC, where all the aforementioned advantages were realized in both the simulation and experimental works.

REFERENCES:

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

[2] J. Anderson and F. Z. Peng, “Four quasi-z-source inverters,” in Proc. IEEE Power Electron. Spec. Conf., 2008, pp. 2743–2749.

[3] Y. Li, J. Anderson, F. Z. Peng, and D. Liu, “Quasi-z-source inverter for photovoltaic power generation systems,” in Proc. 24th Annu. IEEE Appl. Power Electron. Conf. and Expo.,, 2009, pp. 918–924.

[4] T. W. Chun, H. H. Lee, H. G. Kim, and E. C. Nho, “Power control for a PV generation system using a single-phase grid-connected quasi z-source inverter,” in Proc. IEEE 8th Int. Conf. Power Electron. ECCE Asia, 2011, pp. 889–893.

[5] D. Vinnikov, I. Roasto, R. Strzelecki, and M. Adamowicz, “Step-up DC/DC converters with cascaded quasi-z-source network,” IEEE Trans. Ind. Electron., vol. 59, no. 10, pp. 3727–3736, Oct. 2012.

 

 

Aggregation of EVs for Primary Frequency Control of an Industrial Microgrid by Implementing Grid Regulation & Charger Controller

 ABSTRACT:

 After nearly a century with internal combustion engines dominating the transportation sector, it now appears that electric vehicles (EVs) are on the brink of enjoying rapid development due to numerous useful features they possess, such as less operational cost and reduced carbon emissions. EVs can act as load as well as source, by utilizing the technique known as Vehicle-to-Grid (or Grid-to-Vehicle technique if EVs are used as a load). This technique adds key features to an industrial microgrid in the form of primary frequency control and congestion management. In this paper, two controllers (grid regulation and charger controller) are proposed by considering different charging profiles, state of charge of electric vehicle batteries, and a varying number of electric vehicles in an electric vehicle fleet. These controllers provide bidirectional power flow, which can provide primary frequency control during different contingencies that an industrial microgrid may face during a 24-hour period. Simulation results prove that the proposed controllers provide reliable support in terms of frequency regulation to an industrial microgrid during contingencies. Furthermore, simulation results also depict that by adding more electric vehicles in the fleet during the vehicle-to-grid mode, the frequency of an industrial microgrid can be improved to even better levels. Different case studies in this article constitute an industrial microgrid with varied distributed energy resources (i.e. solar and wind farm), electric vehicles fleet, industrial and residential load along with diesel generator. These test cases are simulated and results are analyzed by using MATLAB/SIMULINK.

 KEYWORDS:

1.      Industrial Microgrid

2.      Vehicle to Grid

3.      Electric Vehicle

4.      Grid to Vehicle

5.      Primary Frequency Control

6.      State of Charge

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This paper studies the impact of EVs’ charging on an industrial microgrid. The control scheme is implemented through grid regulation and charger controllers which provide bidirectional power flow. This dual power flow not only provides charging power to EVs but also ensures frequency regulation through active and reactive power support. The charging station consists of a central AC/DC VSC station that injects power into an industrial microgrid and minimizes frequency deviations. Different contingencies have been simulated and their impact on primary frequency is observed. Simulation results prove that the proposed bidirectional charging strategy contributes effectively towards frequency regulation. The frequency is well regulated within the acceptable margin when V2G mode is enabled for EVs’ charging/discharging as compared to when V2G mode was disabled. Frequency regulation improves even further by increasing the number of EVs in the fleet as more vehicles contribute to grid regulation mode. Hence, simulation results prove the robustness of the proposed controllers.

REFERENCES:

[1] P. Zhou and M. Wang, "Carbon dioxide emissions allocation: A review," Ecological Economics, vol. 125, pp. 47-59, 2016.

[2] N. Zhang, K. Yu and Z. Chen, "How does urbanization affect carbon dioxide emissions? A cross-country panel data analysis," Energy Policy, vol. 107, pp. 678-687, 2017.

[3] M. A. Abdelbaky, X. Liu and D. Jiang, "Design and implementation of partial offline fuzzy model-predictive pitch controller for large-scale wind-turbines," Renewable Energy, vol. 145, pp. 981-996, 2020/01/01/ 2020.

[4] M. A. Abdelbaky, X. Liu and X. Kong, "Wind Turbines Pitch Controller using Constrained Fuzzy-Receding Horizon Control," in 2019 Chinese Control And Decision Conference (CCDC), 2019, pp. 236-241.

[5] P. Weldon, P. Morrissey and M. O’Mahony, "Long-term cost of ownership comparative analysis between electric vehicles and internal combustion engine vehicles," Sustainable Cities and Society, vol. 39, pp. 578-591, 2018.