PMSG Based Wind Energy Generation System: Energy Maximization and its Control

ABSTRACT:

This paper deals with the energy maximization and control analysis for the permanent magnet synchronous generator (PMSG) based wind energy generation system (WEGS). The system consists of a wind turbine, a three-phase IGBT based rectifier on the generator side and a three-phase IGBT based inverter on the grid side converter system. The pitch angle control by perturbation and observation (P&O) algorithm for obtaining maximum power point tracking (MPPT). MPPT is most effective under, cold weather, cloudy or hazy days. A designed control technique is proposed for the MPPT mechanism of the system. This paper will explore in detail about the control analysis for both the generator and grid side converter system. Further, it will also discuss about the pitch angle control for the wind turbine in order to obtain maximum power for the complete wind energy generation system. The proposed WEGS for maximization of power is modelled, designed and simulated using MATLAB R2014b Simulink with its power system toolbox and discrete step solver incorporated in the simulation tool.

KEYWORDS:

1.      Maximum power point tracking (MPPT)

2.      Permanent magnet synchronous generator (PMSG)

3.      Pitch angle control (PAC)

4.      Wind energy generation system (WEG)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 Fig. 1. Control issue in PMSG based wind turbine system

EXPECTED SIMULATION RESULTS:

Fig.2. Wind speed (15 m/s).

Fig.3. Pitch angle ( 26 Degree).

Fig.4. Active power output (1.49 MW).

Fig.5. Stator voltage of PMSG (per unit).

Fig.6. Stator current of PMSG (per unit).

Fig.7. Wind speed (m/s).

Fig.8. Pitch control.

Fig.9. Electrical torque of PMSG.

 

Fig.10. Wind turbine power with pitch control.

CONCLUSION:

This paper has briefly discussed about the energy maximization and control analysis for the PMSG based wind energy generation system. The paper also explored in detail about the different control algorithm for both the machine and grid side converter system and has used VSC control for our proposed mechanism. A brief discussion on the pitch angle control for the wind turbine has been described which aims to obtain maximum power for the complete wind energy generation system. A designed control technique named as (P&O) has also been proposed for the MPPT mechanism of the system whose results has been validated using MATLAB R2014b Simulink. As discussed before the presented technique includes maximum power point tracking module, pitch angle control and average model for machine side and grid side converters. Also, the integrated control system controls the generator speed, DC-link voltage and active power along with the above-mentioned factors.

REFERENCES:

[1] M. Benadja and A. Chandra, “A new MPPT algorithm for PMSG based grid connected wind energy system with power quality improvement features”, IEEE Fifth Power India Conference, Murthal, pp. 1-6, 2012.

[2] S. Sharma and B. Singh, “An autonomous wind energy conversion system with permanent magnet synchronous generator”, International Conference on Energy, Automation and Signal, Bhubaneswar, Odisha, pp. 1-6, 2011.

[3] M. Singh and A. Chandra, “Power maximization and voltage sag/swell ride-through capability of PMSG based variable speed wind energy conversion system”,34th Annual Conference of IEEE Industrial Electronics, Orlando, FL, pp. 2206-2211, 2008.

[4] T. Tafticht, K. Agbossou, A. Cheriti and M. L. Doumbia, “Output Power Maximization of a Permanent Magnet Synchronous Generator Based Stand-alone Wind Turbine”,IEEE International Symposium on Industrial Electronics, Montreal, pp. 2412-2416, 2006.

[5] N. A. Orlando, M. Liserre, R. A. Mastromauro and A. D. Aquila, “A Survey of Control Issues in PMSG-Based Small Wind-Turbine Systems”, IEEE Transactions on Industrial Informatics, vol. 9, no. 3, pp. 1211-1221, Aug. 2013.

Power Management in PV-Battery-Hydro Based Standalone Microgrid

 ABSTRACT:

This paper proposes a high-efficiency two stage three-level grid-connected photovoltaic inverter. This work deals with the frequency regulation, voltage regulation, power management and load levelling of solar photovoltaic (PV)-battery-hydro based microgrid (MG). In this MG, the battery capacity is reduced as compared to a system, where the battery is directly connected to the DC bus of the voltage source converter (VSC). A bidirectional DC–DC converter connects the battery to the DC bus and it controls the charging and discharging current of the battery. It also regulates the DC bus voltage of VSC, frequency and voltage of MG. The proposed system manages the power flow of different sources like hydro and solar PV array. However, the load levelling is managed through the battery. The battery with VSC absorbs the sudden load changes, resulting in rapid regulation of DC link voltage, frequency and voltage of MG. Therefore, the system voltage and frequency regulation allows the active power balance along with the auxiliary services such as reactive power support, source current harmonics mitigation and voltage harmonics reduction at the point of common interconnection. The experimental results under various steady state and dynamic conditions, exhibit the excellent performance of the proposed system and validate the design and control of proposed MG.

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1 Microgrid Topology and MPPT Control

(a) Proposed PV-battery-hydro MG,

EXPECTED SIMULATION RESULTS:

Fig. 2 Dynamic performance of PV-battery-hydro based MG following by solar irradiance change

(a) vsab, isc, iLc and ivscc, (b) Vdc, Ipv, Vb and Ib, (c) vsab, isa, iLa and ivsca, (d) Vdc, Ipv, Vb and Ib

.

Fig.3 Dynamic performance of hydro-battery-PV based MG under load perturbation

(a) vsab, isc, Ipv and ivscc, (b) Vdc, Ipv, Vb and Ib, (c) vsab, isc, Ipv and ivscc, (d) Vdc, Ipv, and Vb

CONCLUSION: 

In the proposed MG, an integration of hydro with the battery, compensates the intermittent nature of PV array. The proposed system uses the hydro, solar PV and battery energy to feed the voltage (Vdc), solar array current (Ipv), battery voltage (Vb) and battery current (Ib). When the load is increased, the load demand exceeds the hydro generated power, since SEIG operates in constant power mode condition. This system has the capability to adjust the dynamical power sharing among the different RES depending on the availability of renewable energy and load demand. A bidirectional converter controller has been successful to maintain DC-link voltage and the battery charging and discharging currents. Experimental results have validated the design and control of the proposed system and the feasibility of it for rural area electrification.

REFERENCES:

[1] Ellabban, O., Abu-Rub, H., Blaabjerg, F.: ‘Renewable energy resources: current status, future prospects and technology’, Renew. Sustain. Energy Rev.,2014, 39, pp. 748–764

[2] Bull, S.R.: ‘Renewable energy today and tomorrow’, Proc. IEEE, 2001, 89, (8), pp. 1216–1226

[3] Malik, S.M., Ai, X., Sun, Y., et al.: ‘Voltage and frequency control strategies of hybrid AC/DC microgrid: a review’, IET Renew. Power Gener., 2017, 11, (2), pp. 303–313

[4] Kusakana, K.: ‘Optimal scheduled power flow for distributed photovoltaic/ wind/diesel generators with battery storage system’, IET Renew. Power Gener., 2015, 9, (8), pp. 916–924

[5] Askarzadeh, A.: ‘Solution for sizing a PV/diesel HPGS for isolated sites’, IET Renew. Power Gener., 2017, 11, (1), pp. 143–151

High-Efficiency Two-Stage Three-Level Grid-Connected Photovoltaic Inverte

ABSTRACT:

This paper proposes a high-efficiency two stage three-level grid-connected photovoltaic inverter. The proposed two-stage inverter comprises a three-level step up converter and a three-level inverter. The three-level step up  converter not only improves the power-conversion efficiency by lowering the voltage stress but also guarantees the balancing of the dc-link capacitor voltages using a simple control algorithm; it also enables the proposed inverter to satisfy the VDE 0126-1-1 standard of leakage current. The three-level inverter minimizes the overall power losses with zero reverse-recovery loss. Furthermore, it reduces harmonic distortion, the voltage ratings of the semiconductor device, and the electromagnetic interference by using a three-level circuit configuration; it also enables the use of small and low cost filters. To control the grid current effectively, we have used a feed-forward nominal voltage compensator with a mode selector; this compensator improves the control environment by presetting the operating point. The proposed high-efficiency two-stage three-level grid-connected photovoltaic inverter overcomes the low  efficiency problem of conventional two-stage inverters, and it provides high power quality with maximum efficiency of 97.4%. Using a 3-kW prototype of the inverter, we have evaluated the performance of the model and proved its feasibility.

KEYWORDS:

1.      Transformerless

2.      Multilevel

3.      Dc-ac power conversion

4.      Single-phase

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. Proposed high-efficiency two-stage three-level grid-connected PV inverter circuit diagram.

EXPECTED SIMULATION RESULTS:

Fig.2. Simulation results for the leakage current of the proposed twostage

inverter.

Fig.3. Simulation results for the leakage current using a conventional three-level step-up converter of Fig. 2(b) as dc-dc power conversion stage of two-stage inverter.

CONCLUSION: 

A high-efficiency two-stage three-level grid-connected PV inverter and control system are introduced. Also, a theoretical analysis is provided along with the experimental results. By using the novel circuit configuration, the proposed two-stage inverter performs power conversion with low leakage current and high efficiency; in dc-dc power conversion stage, the connection of midpoints of capacitors enables the proposed two-stage inverter to limit the leakage current below 300mA; in dc-ac power conversion stage, the overall power losses are minimized by eliminating the reverse-recovery problems of the MOSFET body diodes. Besides, the proposed inverter with three voltage levels reduces the power losses, harmonic components, voltage ratings, and EMI; it also enables using small and low cost filters. For the control system, the feedforward nominal voltage compensator also improves the control environment by presetting the operating point. This developed control algorithm makes the proposed inverter feasible. Thus, the proposed high-efficiency two-stage three-level grid connected PV inverter provides high power quality with high power-conversion efficiency. By using a 3-kW prototype, this experiment has verified that the proposed inverter has high efficiency, and the developed control system is suitable for the proposed inverter.

REFERENCES:

[1] B.K. Bose, “Global energy acenario and impact of power electronics in 21st century,” IEEE Transactions on Industrial Electronics, vol. 60, no. 7, pp. 2638-2651, July. 2013.

[2] Y. Zhou, D. C. Gong, B. Huang, and B. A. Peters, “The impacts of carbon tariff on green supply chain design,” IEEE Transactions on Automation Science and Engineering, July. 2015. Available: DOI: 10.1109/TASE.2015.2445316

[3] Y. Wang, X. Lin, and M. Pedram, “A near-optimal model-based control algorithm for households equipped with residential photovoltaic power generation and energy storage systems,” IEEE Transactions on Sustainable Energy, vol. 7, no. 1, pp. 77-86, Jan. 2016.

[4] Y. W. Cho, W. J. Cha, J. M. Kwon, and B. H. Kwon, “Improved  single-phase transformerless inverter with high power density and high efficiency for grid-connected photovoltaic systems,” IET Renewable Power Generation, vol. 10, no. 2, pp. 166-174, Feb. 2016.

[5] A. Shayestehfard, S. Mekhilef, and H. Mokhlis, “IZDPWMBased feedforward controller for grid-connected inverters under unbalanced and distorted conditions,” IEEE Trans. Ind. Electron., vol. 64, no. 1, pp. 14-21, Jan. 2017.

A Three-Phase Symmetrical DC-Link Multilevel Inverter with Reduced Number of DC Sources

ABSTRACT:

 This paper presents a novel three-phase DC-link multilevel inverter topology with reduced number of input DC power supplies. The proposed inverter consists of series-connected half-bridge modules to generate the multilevel waveform and a simple H-bridge module, acting as a polarity generator. The inverter output voltage is transferred to the load through a three-phase transformer, which facilitates a galvanic isolation between the inverter and the load. The proposed topology features many advantages when compared with the conventional multilevel inverters proposed in the literatures. These features include scalability, simple control, reduced number of DC voltage sources and less devices count. A simple sinusoidal pulse-width modulation technique is employed to control the proposed inverter. The performance of the inverter is evaluated under different loading conditions and a comparison with some existing topologies is also presented. The feasibility and effectiveness of the proposed inverter are confirmed through simulation and experimental studies using a scaled down low-voltage laboratory prototype.

KEYWORDS:

1.      Hybrid multilevel inverter

2.      DC-link inverter

3.      half-bridge module

4.      symmetric DC voltage supply

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1 The proposed three-phase CMLI with two half-bridge cells per phase leg

 EXPECTED SIMULATION RESULTS:

Fig. 2 Simulation results of the output line voltages and line currents for (a) load of nearly 0.8–lagging power factor and (b) load of nearly unity power factor

Fig. 3 Simulation results for a dynamic change in the load from nearly unity PF (100.31∠4.49°Ω) to 0.8 lagging PF (127.13∠38.13°Ω): (a) level generator output voltage, (b) polarity generator output voltage (phase voltage) and (c) line voltage and line current

Fig. 4 Simulation results for a dynamic change in the load magnitude with the same PF: (a) Line voltage, (b) Line current

Fig. 5 Simulation results for a dynamic change in the load from nearly 0.9 lagging PF (108.01∠22.21°Ω) to 0.7 lagging PF (142.88∠45.58°Ω): (a) level generator output voltage, (b) polarity generator output voltage (phase voltage) and (c) line voltage and line current

Fig. 6 Simulation results for carrier frequency of 8 kHz: (a) line voltages and currents, (b) line current THD, (c) line voltage THD

CONCLUSION

This paper presents a new symmetrical multilevel inverter topology with two different stages. The proposed inverter requires less power electronic devices and features modularity, hence simple structure, less cost, and high scalability. The number of input DC-supplies for the proposed topology is found to be nearly 67% less than the similar symmetric half-bridge topologies, which is a great achievement for industrial applications. This phenomenon will reduce the complexity of DC voltage management. As being a symmetric structure, all the switching devices experience same voltage stress, which is a very important factor for high voltage applications. The feasibility of the proposed inverter is confirmed through simulation and experimental analysis for different operating conditions.

REFERENCES:

[1] L. G. Franquelo, J. Rodriguez, J. I. Leon, S. Kouro, R. Portillo, and M. A. Prats, "The age of multilevel converters arrives," IEEE Ind. Electron. magazine, vol. 2, pp. 28-39, 2008.

[2] A. Nabae, I. Takahashi, and H. Akagi, "A new neutral-point-clamped PWM inverter," IEEE Trans. Ind. Appl., pp. 518-523, 1981.

[3] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B. Wu, et al., "Recent advances and industrial applications of multilevel converters," IEEE Trans. Ind. Electron., vol. 57, pp. 2553-2580, 2010.

[4] J. Rodriguez, J.-S. Lai, and F. Z. Peng, "Multilevel inverters: a survey of topologies, controls, and applications," IEEE Trans. Ind. Electron., vol. 49, pp. 724-738, 2002.

[5] B. Xiao, L. Hang, J. Mei, C. Riley, L. M. Tolbert, and B. Ozpineci, "Modular cascaded H-bridge multilevel PV inverter with distributed MPPT for grid-connected applications," IEEE Trans. Ind. Appl., vol. 51, pp. 1722-1731, 2015.

Varying Phase Angle Control In Isolated Bidirectional DC–DC Converter For Integrating Battery Storage And Solar PV System In Standalone Mode

 ABSTRACT:

This study proposes a varying phase angle control (VPAC) in isolated bidirectional dc–dc converter (IBDC) for integrating battery storage unit to a DC link in a standalone solar photovoltaic (PV) system. The IBDC is capable of power transfer using high step up/down ratio between DC link and battery. The VPAC control proposed in this study effectively manage the power flow control between the battery storage unit and the solar PV fed DC link by continuously varying the phase angle between high voltage and low voltage (LV) bridge voltage of the IBDC. The solar PV system is incorporated with the maximum power point tracking using DC–DC converter. In order to control the voltage across the AC load a voltage source inverter is used. The study also presents the design aspects of the IBDC converter for the application considered. The performance of the proposed power flow control strategy has been studied through PSCAD/EMTDC simulation and validated using LPC 2148 ARM processor.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1 Block diagram for proposed standalone system

(a) Generalised block diagram, (b) Mode 1 operation, (c) Mode 2 operation, (d) Mode 3 operation

 EXPECTED SIMULATION RESULTS:

.

Fig. 2 Simulation results of IBDC

(a) Battery current during change in mode 1 to mode 2, (b) Battery current during change in mode 2 to mode 1, (c) Solar PV power, load power and battery power during change in

mode 1 to mode 2, (d) Solar PV power, load power and battery power during change in mode 2 to mode 1

CONCLUSION: 

The proposed variable phase angle control of IBDC converter balances the power flow between the solar PV system, battery storage unit and AC load in all the modes. The VPAC algorithm ensures that the, (i) solar PV system delivers maximum demanded power corresponding to the load and battery gets charged/ discharged through the available excess/short power. The governing mathematical formulation of problem reveals the dependency of average battery current on phase angle between the voltages of LV and HV side of the IBDC converter and hence provides a strategy to control the power flow. The analysis presented can be used to design the passive components and switches of the IBDC. From the obtained results, the performance of the proposed VPAC has been established with smooth transition of power flow between the PV fed DC link and the battery through the IBDC converter. The maximum power is extracted from the solar PV and AC load voltage is controlled in all the modes.

REFERENCES:

[1] Bull, S.R.: ‘Renewable energy today and tomorrow’, Proc. IEEE, 2001, 89, (8), pp. 1216–1226

[2] Solodovnik, E.V., Liu, S., Dougal, R.A.: ‘Power controller design for maximum power tracking in solar installations’, IEEE Trans. Power Electron., 2004, 19, (5), pp. 1295–1304

[3] Kuo, Y.-C., Liang, T.-J., Chen, J.-F.: ‘Novel maximum-power-point tracking controller for photovoltaic energy conversion system’, IEEE Trans. Ind. Electron., 2001, 48, (3), pp. 594–601

[4] Koutroulis, E., Kalaitzakis, K., Voulgaris, N.C.: ‘Development of a microcontroller-based, photovoltaic maximum power point tracking control system’, IEEE Trans. Power Electron., 2001, 16, (1), pp. 46–54