Flexibility Enhancement of Hybrid Microgrids Using Optimal H∞ Filtering-based Fuzzy Control of UIPC

ABSTRACT:

The current study focuses on flexibility enhancement of hybrid or ac/dc microgrids (HMGs), which uses an improved Unified Interphase Power Controller (UIPC). The UIPC is adopted as an effective tool for interconnecting the HMG. A novel control system is suggested for UIPC line power converter (LPC). The proposed control scheme is an optimal H∞ filtering-based fuzzy inference system which is able to effectively provide a flexible control for the LPCs during system different conditions, as shown by simulations.

KEYWORDS:

1.      Hybrid microgrid

2.       Flexibility

3.      H∞ filtering

4.      Fuzzy controller

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The HMGs are the most prevalent configurations for smart microgrids. Conventionally, in an HMG, the ac and dc groups of microgrids have been interconnected by the parallel - connected BILPCs. This connection brings many problems into the control and operation of an HMG. The UIPC has been presented in this paper, as a new and effective solution for this problem, instead of using the parallel-connected BILPCs. Also, a new optimal H∞ filtering-based fuzzy control scheme has been proposed for the LPCs in the UIPC to increase the flexibility. The simulation results have confirmed the flexible power transferring performance of the HMGs during various conditions using UIPC.

REFERENCES:

[1] Xiong Liu, et al, "A Hybrid AC/DC Microgrid and Its Coordination Control", IEEE Transactions on Smart Grid, Volume: 2, Issue: 2, pp. 278 - 286, 2011.

[2] S. A Taher, M. Zolfaghari, C. Cho, M. Abedi, M. Shahidehpour, "A New Approach for Soft Synchronization of Microgrid Using Robust Control Theory", IEEE Transactions on Power Delivery Volume: 32, Issue: 3, pp. 1370 – 1381, 2017. J. Clerk Maxwell, A Treatise on Electricity and Magnetism, 3rd ed., vol. 2. Oxford: Clarendon, 1892, pp.68–73.

[3] Xiaonan Lu, et al., "Control of Parallel-Connected Bidirectional ACDC Converters in Stationary Frame for Microgrid Application", IEEE, Energy Conversion Congress and Exposition (ECCE), 2011.

[4] Xiaonan Lu, et al., "Hierarchical Control of Parallel AC-DC Converter Interfaces for Hybrid Microgrids", IEEE Transactions on Smart Grid, Volume: 5, Issue: 2, pp. 683 – 692, 2014.

[5] F. Wang, et al., "Design and Analysis of Active Power Control Strategies for Distributed Generation Inverters under Unbalanced Grid faults", IET Generation, Transmission & Distribution Volume: 4, Issue: 8, pp. 905 - 916 2010.

Energy Management and Control Strategy of Photovoltaic/Battery Hybrid Distributed Power Generation Systems With an Integrated Three-Port Power Converter

ABSTRACT:

Photovoltaic (PV)/battery hybrid power units have attracted vast research interests in recent years. For the conventional distributed power generation systems with PV/battery hybrid power units, two independent power converters, including a unidirectional dc_dc converter and a bidirectional converter, are normally required. This paper proposes an energy management and control strategy for the PV/battery hybrid distributed power generation systems with only one integrated three-port power converter. As the integrated bidirectional converter shares power switches with the full-bridge dc_dc converter, the power density and the reliability of the system is enhanced. The corresponding energy management and control strategy are proposed to realize the power balance among three ports in different operating scenarios, which comprehensively takes both the maximum power point tracking (MPPT) benefit and the battery charging/discharging management into consideration. The simulations are conducted using the Matlab/Simulink software to verify the operation performance of the proposed PV/battery hybrid distributed power generation system with the corresponding control algorithms, where the MPPT control loop, the battery charging/discharging management loop are enabled accordingly in different operating scenarios.

KEYWORDS:

1.      Energy management

2.       Maximum power point tracking

3.      Bidirectional power converter

4.      Photovoltaic/battery hybrid power unit

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

An integrated three-port power converter as the interface for the PV/battery hybrid distributed power generation system is proposed. Compared with the conventional system topology containing an independent DC-DC unidirectional conversion stage and a bidirectional conversion stage, the proposed system has advantages in terms of higher power density and reliability. The phase shift angle of the full bridge and the switch duty cycle are adopted as two control variables to obtain the required DC bus voltage and realize the power balance among three ports. Different operating scenarios of the system under various power conditions are discussed in detail and a comprehensive energy management and control strategy is proposed accordingly. The priority controller can enable one of the control loops in different scenarios to optimize the whole system performance, taking both the MPPT benefit and the battery charging/discharging management requirements into consideration. The simulation results verify the performance of the proposed PV/battery hybrid distributed power generation system and the feasibility of the control algorithm.

REFERENCES:

[1] F. Blaabjerg, Z. Chen, and S. B. Kjaer, ``Power electronics as efficient interface in dispersed power generation systems,'' IEEE Trans. Power Electron., vol. 19, no. 5, pp. 1184_1194, Sep. 2004.

[2] J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galvan, R. Potillo, M. M. Prats, J. I. Leon, 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, Jun. 2006.

[3] BP Statistical Review of World Energy, British Petroleum, London, U.K., Jun. 2018.

[4] J. P. Barton and D. G. In_eld, ``Energy storage and its use with intermittent renewable energy,'' IEEE Trans. Energy Convers., vol. 19, no. 2, pp. 441_448, Jun. 2004.

[5] M. S. Whittingham, ``History, evolution, and future status of energy storage,'' Proc. IEEE, vol. 100, pp. 1518_1534, May 2012.

Distributed virtual inertia control and stability analysis of dc microgrid

 ABSTRACT:

A dc microgrid is a low inertia system dominated by power converters. As a result, the change rate of the dc voltage is very fast under power variation. In this study, a distributed virtual inertia control is proposed to enhance the inertia of the dc microgrid and decrease the change rate of the dc voltage. The inertia of the dc microgrid can be enhanced by the kinetic energy in the rotor of the permanent magnet synchronous generators (PMSG)-based wind turbine, the energy stored in batteries and the energy from the utility grid. By introducing a virtual inertia control coefficient, a general expression of the inertial power provided by each controllable power sources is defined. The proposed inertia control is simply a first-order inertia loop and is implemented in the grid-connected converter, the battery interfaced converter and the PMSG interfaced converter, respectively. The small-signal model of the dc microgrid with the proposed inertia control is established. The range of virtual inertia control coefficient is determined through stability analysis. Finally, a typical dc microgrid is built and simulated in Matlab/Simulink, and the effectiveness of the proposed control strategy and correctness of the stability analysis are verified.

 SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, the virtual inertia control of the dc microgrid is proposed and the small-signal stability analysis is carried out for the dc microgrid with virtual inertia control. Conclusions are summarised as follows:

i. Considering the potential of inertial support capability of rotating equipment and storage equipment in the dc microgrid, the virtual inertial control of G-VSC, W-VSC and B-DC, are designed to provide a virtual inertial support for the system. Especially, the inertia power provided by the utility grid, wind turbine and battery can be adjusted by modifying the corresponding coefficient of virtual inertia control.

ii. A small-signal model of the dc microgrid is established. The stability of the dc microgrid with additional virtual inertia control is analysed and the range of the virtual inertia control coefficient is determined.

iii. The proposed virtual inertia control is suitable for both ac/dc converters and dc/dc converters, and is unconstrained by the voltage hierarchical coordinated control strategy. Once the voltage fluctuation occurs, the inertia power provided by the proposed virtual inertia control can help to improve the inertia of the system.

REFERENCES:

[1] Dragicevic, T., Lu, X., Vasquez, J.C., et al.: ‘DC microgrids-part I: a review of control strategies and stabilization techniques’, IEEE Trans. Power Electron., 2016, 31, (7), pp. 4876–4891

[2] Cairoli, P., Kondratiev, I., Dougal, R.A.: ‘Coordinated control of the bus tie switches and power supply converters for fault protection in DC microgrids’, IEEE Trans. Power Electron., 2013, 28, (4), pp. 2037–2047

[3] Chen, Y.-K., Wu, Y.-C., Song, C.-C., et al.: ‘Design and implementation of energy management system with fuzzy control for DC microgrid systems’, IEEE Trans. Power Electron., 2013, 28, (4), pp. 1563–1570

[4] Zhou, T., Francois, B.: ‘Energy management and power control of a hybrid active wind generator for distributed power generation and grid integration’, IEEE Trans. Power Electron., 2011, 58, (1), pp. 95–104

[5] Lyu, X., Xu, Z., Zhao, J., et al.: ‘Advanced frequency support strategy of photovoltaic system considering changing working conditions’, IET Gener. Transm. Distrib., 2018, 12, (2), pp. 363–370

Distributed Incremental Adaptive Filter Controlled Grid Interactive Residential Photovoltaic-Battery Based Microgrid for Rural Electrification

ABSTRACT:

 In this paper, a distributed incremental adaptive filter (DIAF) controlled utility interfaced photovoltaic (PV) - battery microgrid system is presented with power quality features. From protection aspects, grid tied solar inverters are required to shut down at loss of the utility. However, the multi-purpose PV-battery system is developed to provide energy to the critical loads, even at loss of distribution network. The bidirectional controlled converter with a battery also mitigates the intermittency of a PV array under rapid variations in the weather. The extracted maximum power is supplied to the voltage source converter (VSC), which is transferred to the nonlinear loads and the utility. The distributed incremental adaptive filter is used to control the VSC with contribution of PV power and the battery. In addition, the DIAF control provides harmonics mitigation, load balancing and power factor improvement functionalities in order to deal with system connected with nonlinear loads. A PV power feed-forward (PVFF) term is incorporated in the current control for injection of active power to the utility as well as to improve the dynamic operation of residential PV-battery microgrid. The battery energy storage (BES) reduces the fuel bills and it is also utilized to provide smoothing attributes to the microgrid. The effectiveness of PV-battery microgrid is validated experimentally developed in the laboratory.

KEYWORDS:

1.      PV-battery microgrid

2.      Power quality and distributed incremental adaptive filter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The distributed incremental adaptive filter (DIAF) based control of residential PV/battery microgrid system for rural electrification, has been demonstrated for it’s satisfactorily operation. The focus of this topology has proved continuous supply by integrating the battery back-up with a PV array even under the outage of PV array and utility grid. The charging and discharging of the battery depending upon the state of charge (SOC) level, have been decided by the cascaded PI control. Test results of extracted PV energy and dynamic load and insolation change are studied for validation of control technique. Moreover, the power quality indices are provided, which are within limit of the IEEE-519 standard.

REFERENCES:

[1] M. Rehmani, M. Reisslein, A. Rachedi, M. Kantarci and M. Radenkovic, “Integrating Renewable Energy Resources Into the Smart Grid: Recent Developments in Information and Communication Technologies,” IEEE Trans. Ind. Infor., vol. 14, no. 7, pp. 2814-2825, July 2018.

[2] N. Babu, R. Peesapati, and G. Panda, “An Adaptive Differentiation Frequency based Advanced Reference Current Generator in Grid-tied PV Applications,” IEEE Journal of Emerging and Selected Topics in Power Electronics (Early Access).

[3] S. Jain, M. Shadmand and R. Balog, “Decoupled Active and Reactive Power Predictive Control for PV Applications using a Grid-tied Quasi- Z-Source Inverter,” IEEE Journal of Emer. and Selected Topics in Power Electron, Early Access, 2018.

[4] L. Zhang, K. Sun, Y. Li, X. Lu and J. Zhao, “A Distributed Power Control of Series-Connected Module-Integrated Inverters for PV Grid- Tied Applications,” IEEE Trans. Power Electron., vol. 33, no. 9, pp. 7698-7707, Sept. 2018.

[5] B. Liu, L. Wang, D. Song, M. Su, J. Yang, D. He,Z. Chen and S. Song “Control of Single-phase Grid-connected Photovoltaic Inverter under Battery Input Condition in Residential Photovoltaic/Battery Systems,” IEEE Trans. Sustain. Energy, vol. 9, no. 4, pp. 1957-1968, Oct. 2018.

 

Development of Wind and Solar Based AC Microgrid with Power Quality Improvement for Local Nonlinear Load using MLMS

ABSTRACT:

 This work proposes a microgrid (μ-grid) integrating wind and solar photovoltaic (PV) resources, along with the battery energy storage (BES) to the three phase grid feeding the nonlinear load. The μ-grid disconcerted by probabilistic nonlinear time dependent parameters and their effects are compensated by cohesive controllers used for utility grid side voltage source converter (GVSC) and machine side VSC (MVSC). The switching controls and the reconfigurability of the μ-grid are addressed on imperative aspects of improving power quality (PQ), power reliability, nonlinear load compensation and economic utilization of resources. The nonlinear load compensation and PQ enhancement are achieved by executing modified version of the adaptive filtering technique including “momentum” based least mean square (MLMS) control technique, utilized for providing the switching control signals to the GVSC. It utilizes two preceding gradient weights for obtaining updated weight thereby improving the convergence rate and overcoming the limitation of conventional control of the same family. The MVSC acquires its switching signals from conventional vector control scheme and the encoderless estimation of speed and rotor position of the synchronous generator (SG) driven by wind turbine through back electromotive force control technique. The external environmental disturbances are overcome by utilizing perturb and observe (P&O) maximum power point (MPP) for wind optimal power extraction and adaptive P&O with variable perturbation step size for solar MPP estimation. Test results are obtained from the laboratory prototype under steady state and dynamic conditions including altering wind speed, intermittent solar insolation and variable load conditions. The PQ issues are addressed and investigated successfully.

KEYWORDS:

1.      Wind Power Generation

2.      Solar PV Power Generation

3.      AC Microgrid

4.      MLMS

5.      MPP and Power Quality

 SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The proposed wind-solar AC microgrid has been designed and implemented to illustrate its improved PQ performance for local nonlinear load using MLMS adaptive control. The weight component and system performance using MLMS has been found with reduced oscillations. Effectiveness of the MLMS is realized through successful harmonic elimination, extraction of load current fundamental component with low static error and faster convergence rate. The wide range of wind speeds, solar insolation and load variations have been considered and the test results obtained from the prototype provide exceedingly well performance for the entire operational range. The grid current THD has been found well within the IEEE-519 harmonic standard. The proposed system has operated well under all the dynamic conditions as well as the power quality issues are mitigated satisfactorily.

 REFERENCES:

[1] R. Cuzner, “The socially responsible microgrid,” IEEE Electrif. Mag., vol. 6, no. 4, pp. 2-5, Dec. 2018.

[2] P. J. Chauhan, B. D. Reddy, S. Bhandari and S. K. Panda, “Battery energy storage for seamless transitions of wind generator in standalone microgrid,” IEEE Trans. Ind. Appl., vol. 55, no. 1, pp. 69-77, Jan.-Feb. 2019.

[3] M. Farhadi and O. Mohammed, “Energy storage technologies for high-power applications,” IEEE Trans. Ind. Appl., vol. 52, no. 3, pp. 1953-1961, May-June 2016.

[4] X. Hou, Y. Sun, J. Lu, X. Zhnag, L. H. Koh, M. Su and J. M. Guerrero, “Distributed hierarchical control of AC microgrid operating in grid-connected, islanded and their transition modes,” IEEE Access, vol. 6, pp. 77388-77401, 2018.

[5] S. Boudoudouh and M. Maaroufi, “Renewable energy sources integration and control in railway microgrid,” IEEE Trans. Ind. Appl., Early Access, 2019.

Detection of the faults in the photovoltaic array under normal and partial shading conditions

ABSTRACT:

This paper propounds a novel technique for detection of the faults in photovoltaic array by using Artificial Neural Network. By using a simulation model, the power variation under different faulty conditions such as open circuit fault, short circuit fault, and bridging fault are measured under normal and partial shading conditions. The simulated attributes are given to the Artificial Neural Network to predict the type of fault occurred in or between photovoltaic modules. Finally, three different training algorithms of Artificial Neural Network are compared for fault detection with help of mean square error as the performance parameter.

KEYWORDS:

1.      Fault detection

2.      Photovoltaic array

3.      Artificial neural network

4.      Open circuit fault

5.      Short circuit fault

6.      Bridging fault

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, the fault detection method is proposed to detect the fault occurred in or between the PV modules. The performance of PV module has been investigated in this paper for different faults such as open circuit fault, short circuit fault and bridging fault under normal and partial shaded conditions. ANN is used to detect the faults occurred in or between PV modules under normal and partial shading conditions and it is tested with random inputs. Future work is to locating the fault in the large scale PV system.

REFERENCES:

[1] Liqun Liu, Xiaoli Meng and Chunxia Liu, “ A review of maximum power point tracking methods of PV power system at a uniform and partial shading”, International Journal on Renewable and Sustainable Energy Reviews, Vol.53, pp.1500-1507,2016.

[2] Kashif Ishaque and Zainal Salam, “ A review of maximum power point tracking techniques of PV system for uniform insolation and partial shading condition”, International Journal on Renewable and Sustainable Energy Reviews, Vol.19, pp.475-488,2013.

[3] M. Sabbaghpur Arani and M.A Hejazi, “ The comprehensive study of electrical faults in PV array”, Journal of Electrical and Computer Engineering, Volume 2016.

[4] S.Saravan and N.Ramesh Babu, “Maximum power point tracking algorithms for the photovoltaic system- A review”, International Journal on Renewable and Sustainable Energy Reviews, Vol.57, pp.192-204, 2016.

[5] K.L.Lian, J.H.Jhang, and I.S.Tian, “ A maximum power point tracking method based on perturb-and-observe combined with particle swarm optimization”, IEEE Journal of Photovoltaic, Vol.4, No.2,pp.626-633,2014.

Design and Modelling of a CSC Converter with a variable DC link voltage to drive a Brushless DC Motor Drive

ABSTRACT:

The applications based on Brushless DC motors are rapidly increasing in both industrial and domestic applications. This paper concerns the design, modeling, and analysis of canonical switching cell converter(CSCC) fed brushless DC motor. CSCC converter is one of the advanced converter topology offering a variable DC link voltage enabling it to suit a multitude of applications. MATLAB/Simulink is used to design and simulate the converter circuits. The modeled converter is employed to drive a BLDC motor and analyzed for different load conditions (Torque) and different DC link voltages to ensure the adaptability of the converter topology to suit a multitude of applications and conclusions has been drawn based on the analysis

KEYWORDS:

1.      BLDC motor

2.      DC-DC converters

3.      Canonical switching Cell converter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The paper presents the design procedure of 500-watt CSCC with a variable output voltage (70 V – 200V), along with a performance analysis of BLDC motor fed by the designed CSCC. The analysis goes with testing of the motor for various DC link voltage and load torque. The static and dynamic performance of the machine is presented along with the IAE, ITAE and ripple factor. The analysis of canonical switching cell converter fed brushless DC drives shows that the CSCC would be a better choice of front end converter to feed BLDC drive to accompt it in multitude of applications.

REFERENCES:

[1] B. Singh and S. Singh, “Single-phase power factor controller topologies for permanent magnet brushless DC motor drives,” IET Power Electronics, vol.3, no.2, pp.147- 175, March 2010.

[2] Chang Liang Xia, Permanent Magnet Brushless DC Motor Drives and Controls, Wiley Press, Beijing, 2012.

[3] P. Pillay and R. Krishnan, “Modeling of permanent magnet motor drives,” IEEE Trans. Ind. Elect., vol.35, no.4, pp.537-541, Nov 1988.

[4] M. A. Rahman and P. Zhou, “Analysis of brushless permanent magnet synchronous motors,” IEEE Trans. Ind. Elect., vol.43, no.2, pp.256-267, Apr 1996.

[5] Xiaoyan Huang, A. Goodman, C. Gerada, Youtong Fang and Qinfen Lu,“A Single Sided Matrix Converter Drive for a Brushless DC Motor in Aerospace Applications,” IEEE Trans. Ind. Elect., vol.59, no.9, pp.3542-3552, Sept. 2012.5