Voltage and Frequency Control of a Stand-alone Wind-Energy Conversion System Based on PMSG

ABSTRACT:

This paper presents a control strategy for a standalone wind-energy conversion system using Permanent Magnet Synchronous Generator (PMSG). The presented control strategy aims at regulating the load voltage in terms of magnitude and frequency under different operating conditions including wind speed variation, load variation and the unbalanced conditions. The wind generating-system under study consists of a wind turbine, PMSG, uncontrolled rectifier, DC-DC boost converter and voltage source inverter. The presented control strategy is based firstly upon controlling the duty cycle of the boost converter in order to convert the variable input dc-voltage, due to different operating conditions, to an appropriate constant dc voltage. Hence, a sinusoidal pulse width modulated (SPWM) inverter is used to regulate the magnitude and frequency of the load voltage via controlling the modulation index. In order to verify the performance of the employed wind generating-system, a sample of simulation results is obtained and analyzed. The presented simulation results show the effectiveness of the employed control strategy to supply the load at constant voltage and frequency under different operating conditions.

KEYWORDS:

  1. Wind turbine
  2. PMSG
  3. Voltage and frequency control

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1.Complete structure of the stand-alone wind-energy conversion system

EXPECTED SIMULATION RESULTS:

Fig. 2.Effect of wind-speed variation on the generated voltage and frequency: a) Wind speed b) generated line voltage c) frequency of the generated voltage

Fig. 3. DC-link voltage

Fig. 4. Load voltage and current during different periods of wind-speed

variation a) Effective value of the load voltage b) Instantaneous three-phase

load-current waveforms

Fig. 5. Effect of load variation on the generated voltage and frequency at constant wind speed a) generated line voltage b) frequency of the generated voltage

Fig. 6. Load voltage and current during different periods of load variations a) Effective value of load voltage during different loads b) Instantaneous threephase load-current waveforms

Fig. 7 DC Link Voltage during balanced and unbalanced

Fig. 8. Effective value of the load voltage during both balanced and

unbalanced loading condition

Fig. 9. Load current of each phase during both balanced and unbalanced loading conditions (a) Instantaneous waveforms (b) Effective value

CONCLUSION:

This paper has presented a control strategy of a stand-alone wind-driven Permanent Magnet Synchronous Generator (PMSG) in order to regulate the magnitude and frequency of the load voltage under different operating conditions. In order to ensure the validity of the presented control strategy, the performance characteristics of the wind-generating system has been studied and discussed under three different operating conditions; wind-speed variation, load variation and unbalance operating condition. The presented simulation results have verified the effectiveness of the control strategy to maintain the load voltage and frequency at a constant level under different operating conditions. This has been achieved by controlling the duty cycle of the employed DC-DC boost converter in order to maintain the DC-link voltage constant at a predetermined value. In addition, the magnitude and frequency of the load voltage has been maintained constant via controlling the modulation index of the load-side SPWM inverter. A constant modulation index has been used in the case of balanced loading conditions. However, different modulation index for each phase has been used in case of unbalanced loading conditions.

REFERENCES:

[1] Aditya Venkataraman, Ali Maswood, Nirnaya Sarangan, Ooi H.P. Gabriel “An Efficient UPF Rectifier for a Stand-Alone Wind Energy Conversion System,” IEEE Trans. on industry applications, vol. 50, NO.2, Marsh/April. 2014

[2] Y. Izumi, A. Pratap, K. Uchida, A. Uehara, T. Senjyu, A. Yona, “A control method for maximum power point tracking of a PMSG-based WECS using online parameter identification of wind turbine,” Proc. Of the IEEE 9th International Conf. on Power Electronics and Drives Systems, Singapore, 5–8 Dec. 2011, pp. 1125–1130.

[3] M. Singh, A. Chandra, B. Singh, “Sensorless power maximization of PMSG based isolated wind-battery hybrid system using adaptive neurofuzzy controller,” IEEE Ind. Appl. Soc. Annual Meeting, 2010, pp. 1-6.

[4] Nishad Menddis, Kashem M. Muttaqi, Sarath Perara “Management of Battery-Supercapacitor Hybrid Energy Storage and Synchronous Condenser for Isolated Operation of PMSG Based Variable-speed wind Turbine Generating Systems“IEEE Trans. ON SMART GRID, vol. 5, NO.2, MARCH 2014

[5] Luminita BAROTE, Corneliu MARINESCU “Modeling and Operational Testing of an Isolated Variable Speed PMSG Wind Turbine with Battery Energy Storage,” Advances in Electrical and Computer Engineering, vol. 12, No. 2, 2012. For equivalent circuit of PMSG

Low Switching Frequency based Asymmetrical Multilevel Inverter Topology with Reduced Switch Count

ABSTRACT:

Multilevel inverters (MLI) since its inception have caught the attention of researchers for medium and high power application. However, there has always been a need for a topology with a lower number of device count for higher efficiency and reliability. A new single phase MLI topology has been proposed in this paper to reduce the number of switches in the circuit and obtain higher voltage level at the output. The basic unit of the proposed topology produces 13 level at the output with three dc voltage sources and eight switches. Three extention of the basic unit have been proposed in this paper. A detailed analysis of the proposed topology has been carried out to show the superiority of the proposed converter with respect to the other existing MLI topologies. Power loss analysis has been done using PLECS software, results in maximum efficiency of 98.5%. Nearest level control (NLC) pulse width modulation technique has been used to produce gate pulses for the switches to achieve better output voltage waveform. The various simulation results have been performed in the PLECS software and a laboratory setup has been used to shows the feasibility of the proposed MLI topology.

KEYWORDS:

  1. DC-AC converter
  2. Multilevel inverter
  3. Reduce switch count
  4. Nearest level control (NLC)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1. Basic unit of the proposed topology

EXPECTED SIMULATION RESULTS:

Figure 2. Simulation results with (a) dynamic change of modulation index (b) FFT of 13 level output voltage and current with Z=10Ω+100mH and (c) output voltage and current waveforms with change of load from Z=50Ω to Z=50Ω+100Mh

CONCLUSION:

The paper presents a novel MLI topology with multiple extension capabilities. The basic unit of the proposed topology produces 13 levels using eight unidirectional switches and three dc voltage sources. Three different extension of the basic unit has been proposed. The performance analysis of the basic unit of the proposed topology has been done and the comparative results with some recently proposed topologies in literature have been presented in the paper. Further, a power loss analysis of the dynamic losses (switching and conduction) in the MLI has also been presented, which gives the maximum efficicnecy of the basic unit as 98.5%. The power loss distribution in all the switches for different combination of loads have also been demonstrated in the paper. The performance of the proposed topology has been simulated with dynamic modulation indexes and different combination of loads using PLECS sorftware. A prototype of the basic unit has been developed in the laboratory and the simulation results have been validated using the different expriemntal results considering different modulation indexes.

REFERENCES:

[1] S. Kouro et al., “Recent Advances and Industrial Applications of Multilevel Converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553–2580, 2010.

[2] H. Abu-Rub, J. Holtz, J. Rodriguez, and Ge Baoming, “Medium-Voltage Multilevel Converters—State of the Art, Challenges, and Requirements in Industrial Applications,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2581–2596, Aug. 2010.

[3] H. Akagi, “Multilevel Converters: Fundamental Circuits and Systems,” Proc. IEEE, vol. 105, no. 11, pp. 2048–2065, Nov. 2017.

[4] J. I. Leon, S. Vazquez, and L. G. Franquelo, “Multilevel Converters: Control and Modulation Techniques for Their Operation and Industrial Applications,” Proc. IEEE, vol. 105, no. 11, pp. 2066–2081, Nov. 2017.

[5] J. Venkataramanaiah, Y. Suresh, and A. K. Panda, “A review on symmetric, asymmetric, hybrid and single DC sources based multilevel inverter topologies,” Renew. Sustain. Energy Rev., vol. 76, pp. 788–812, Sep. 2017.

Intelligent Energy Control Center for Distributed Generators Using Multi-Agent System

ABSTRACT:

This paper presents the modeling of intelligent energy control center (ECC) controlling distributed generators (DGs) using multi- agent system. Multi-agent system has been proposed to provide intelligent energy control and management in grids because of their benefits of extensibility, autonomy, reduced maintenance, etc. The multi -agent system constituting the smart grid and agents such as user agent, control agent, database agent, distributed energy resources (DER) agent work in collaboration to perform assigned tasks. The wind power generator connected with local load, the solar power connected with local load and the ECC controlled by fuzzy logic controller (FLC) are simulated in MATLAB/SIMULINK. The DER model is created in client and ECC is created in server. Communication between the server and the client is established using transmission control protocol/internet protocol (TCP/IP). The results indicate that the controlling of DER agent can be achieved both from server and client.

KEYWORDS:

  1. Distributed energy resources (DER) and trans-mission control protocol/internet protocol (TCP/IP)
  2. Distributed generators (DGs)
  3. Energy control center (ECC)
  4. Fuzzy logic controller (FLC)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of ECC.

EXPECTED SIMULATION RESULTS:

Fig. 2. Voltage waveform of wind and solar power – circuit breaker (CB-1) closed after 0.1 s and circuit breaker (CB-2) closed after 0.3 s to interconnect solar power to wind.

Fig. 3. Voltage waveform of wind and solar power circuit breaker (CB-1) closed after 0.1 s and circuit breaker (CB-2) closed after 0.3 s to interconnect solar power to wind observed up to 0.6 s.

Fig. 4. Three-phase voltage waveform of the power system.

Fig. 5. Three-phase current waveform of the power system.

Fig. 6. System frequency waveform of the power system.

CONCLUSION:

The simulation model of ECC, controlling the solar power generation and wind power generation interconnected with grid using multi-agent system is described in this paper. The voltage of wind and solar power are stored in a excel sheet as a database agent. Intelligent controller the switch provided in the solar panel to add/remove depending upon the voltage requirements. This excel sheet acting as a monitoring tool to access the simulation results, provides the visualization of the grid. The results prove that the multi-agent component controls the Distributed Energy Resources.

REFERENCES:

[1] T. Nagata and H. Sasaki, “A multi-agent approach to power system restoration,” IEEE Trans. Power Syst., vol. 17, no. 2, pp. 457–462, May 2002.

[2] T. A. Dimeas and N. D. Hatziargyriou, “Operation of a multiagent system for microgrid control,” IEEE Trans. Power Syst., vol. 20, no. 3, pp. 1447–1455, Aug. 2005.

[3] S. G. Ankaliki, “Energy control center functions for power system,” Int. J. Math. Sci., Technol., Humanities, vol. 2, no. 1, pp. 205– 212, 2012

[4] R. L. Krutz, Securing SCADA Systems. New York, NY, USA: Wiley, 2006.

[5] O. Castillo and P. melin, Studies in Fuzziness and Soft Computing Type2 Fuzzy Logic : Theory and Applications. New York, NY, USA: Springer-Verlag, 2008.

Integration of Super capacitor in Photovoltaic Energy Storage: Modelling and Control

ABSTRACT:

Due to the variable characteristics of photovoltaic energy production or the variation of the load, batteries used in storage systems renewable power can undergo many irregular cycles of charge 1 discharge. In turn, this can also have a detrimental effect on the life of the battery and can increase project costs. This paper presents an embedded energy share method between the energy storage system (battery) and the auxiliary energy storage system such as super capacitors (SC). Super capacitors are used to improve batteries life and reduce their stresses by providing or absorbing peaks currents as demanded by the load. The photovoltaic cells are connected to DC bus with boost converter and controlled with MPPT algorithm, Super capacitors and batteries are linked to the DC bus through the buck-boost converter. The inductive load is connected to the DC bus by a DC-AC converter. The static converters associated with batteries and super capacitors are controlled by current. The components of the systems are supervised through a block of energy management. The complete model of the system is implemented in MATLAB/Simulink environment. Simulation results are given to show the performance of the proposed control strategy, for the overall system.

KEYWORDS:

  1. Photovoltaic
  2. Batteries
  3. Super capacitors
  4. DC bus
  5. Energy storage
  6. Energy management
  7. Converters control

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1. Schematic diagram of photovoltaic energy storage.

EXPECTED SIMULATION RESULTS:

Figure 2. Solar irradianee.

Figure 3. Simulation of ip,’ and itoadwith variable solar irradianee.

Figure 4. Simulation of isc and hal with variable solar irradianee.

Figure 5. Simulation of hood and fpv with variable load.

Figure 6. Simulation of isc and hal with variable load.

Figure 7. Simulation of Vdc with variable load.

Figure 8. Simulation of TLoad and [bat with null photovoltaic current.

Figure 9. Simulation of Iscd 1 with null photovoltaic current.

CONCLUSION:

In this paper, the storage photovoltaic energy by using a combination of Battery-Supercapacitor has been presented. First, the modeling of different components of the system has been addressed. A comparison of different model of SCs is given. Second, a strategy of control and regulation of the DC bus voltage was proposed, to deal with the variation of solar irradiation and/or the variation of the load. This controller gives the better an effIcient energy management and ensures continuity of supply by using the methodology that involves a reversible chopper between the batteries and the DC bus and another between the SC and the DC bus to ensure stable voltage on the DC bus of 400V. The three operating scenarios show that the proposed control and management strategies of DC bus are effective and able to supply desired power. It is also shown that SCs can absorb rapid changes in current to reduce the stress on batteries.

REFERENCES:

[1] L. Peiwen, “Energy storage is the core of renewable technologies,” Nanotechnol. Mag., vol. 2, no. 4, pp. 13-18, Dec. 2008.

[2] Q. Liyan and Q. Wei, “Constant power control of DFTG wind turbines with supercapacitor energy storage,” iEEE Trans. Ind. Appl., vol. 47, no. I, pp. 359-367, Jan. 2011.

[3] M. Uzunoglu and M. S. Alam, “Dynamic modeling, design, and simulation of a combined PE M fuel cell and ultracapacitor system for stand-alone residential applications,” IEEE Trans. Energy Convers., vol. 21,no. 3,pp. 767-775,Sep. 2006.

[4] B. P. Roberts and C. Sandberg,’The role of energy storage in development of smart grids,” Proc. IEEE, vol. 99, no. 6, pp. 1139-1144, June. 2011.

[5] A Khaligh and L. Zhihao, “Battery, ultracapacitor, fuel cell, and hybrid energy storage systems for electric, hybrid electric, fuel cell, and plugin hybrid electric vehicles: State-of-the -art,” IEEE Trans. Veh. Technol, vol. 59, no. 6, pp. 2806-2814, Jully. 2010.

Implementation of Solar Photovoltaic System with Universal Active Filtering Capability

ABSTRACT:

In this work, a novel technique based on second order sequence filter and proportional resonant controller is proposed for control of universal active power filter integrated with PV array (UAPF-PV). Using a second order sequence filter and sampling it at zero crossing instant of the load voltage, the active component of distorted load current is estimated, which is used to generate reference signal for shunt active filter. The proposed method has good accuracy in extracting fundamental active component of distorted and unbalanced load currents with reduced mathematical computations. Along with power quality improvement, the system also generates clean energy through the PV array system integrated to its DC-link. The UAPF-PV integrates benefits of power quality improvement and distributed generation. The system performance is experimentally evaluated on a prototype in the laboratory under a variety of disturbance conditions such as PCC voltage fall/rise, load unbalancing and variation in solar irradiation.

For Simulation Results Contact us @ 9347143789.

Grid-Connected Shunt Active LCL Control via Continuous Sliding Modes

ABSTRACT:

A LCL grid connected three phases and three wires shunt active filter (SAF) is studied and controlled. It is known that SAFs generate distortive components caused by a high switching frequency of a voltage source inverter (VSI). In order to prevent spreading these distortive components to the grid, the LCL filter (usually controlled by a linear control feedback) is used; while a parasitic phase shift/lag between the reference and injected currents emerges and severely deteriorates the filtration quality. In this work, inherently robust sliding mode controller (SMC) is used in the shunt active filter, for reducing the phase shift effects over the broad bandwidth, while improving robustness to system’s disturbances. Furthermore, in order to prevent very high frequency switching of the SMC that can severely hurt the switching elements, two different continuous SMCs are employed and studied. In the first solution, a signum function used in discontinuous SMC is replaced by a continuous sigmoid function. The second proposed solution uses an artificial increase of input-output relative degree, that allows designing SMC in terms of the control derivative, while the actual SMC function becomes continuous by integrating the discontinuous SMC. The output of the continuous SMC is pulse-width modulated (PWM) in order to provide a fixed given frequency of control switching, required for the VSI safe operation. The proposed approach was validated on a mathematically modeled conventional nonlinear load and a real textile factory, (Aleppo, Syria) via simulation based on real measurements coming from power quality analyzers. A new modeling approach of nonlinear loads is proposed and the efficacy of the proposed controllers for SAF/LCL filter, even under unbalanced conditions, is validated via simulations.

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Fast Repetitive Control With Harmonic Correction Loops for Shunt Active Power Filter Applied in Weak Grid

ABSTRACT:

This paper proposes a fast repetitive control (FRC) scheme with harmonic correction loops for the three-phase three wire shunt active power filter (APF) applied in weak power grid.  The FRC scheme consists of a repetitive control loop which is designed in the synchronous rotational frame and a fractional delay (FD) filter for approximating the FD caused by the fixed sampling rate. It can significantly improve the dynamic performance for the harmonic compensation. In weak grid situation, the grid frequency, voltage and then harmonic currents would vary rapidly with disturbances. A cumulative error cancellation loop is introduced into the FRC to improve the harmonic detection accuracy when grid frequency drifts. The harmonic correction loops are proposed to correct the harmonic references with selected orders when they vary rapidly with the grid voltage. With such loops, the compensation precision of the shunt APF can be highly improved. Simulation and experiment results verified the effectiveness of the proposed scheme.

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A Unified Power Flow Controller Using a Power Electronics Integrated Transformer

ABSTRACT:

This paper presents a Unified Power Flow Controller (UPFC) application of the Custom Power Active Transformer (CPAT); a power electronics integrated transformer which provides services to the grid through its auxiliary windings. The CPAT structure integrates three single-phase transformers into one shunt-series combining transformer. This integration empowers a sub-station with the capability of dynamically regulating the terminal voltage and current of a transformer through isolated power electronics converters. This paper investigates the CPAT’s capability to provide UPFC services which includes power flow control, reactive power compensation, voltage regulation and harmonics elimination. Simulations of the CPAT-UPFC with a stiff grid and a 5-bus power system demonstrates its functionality as an inter-bus coupling transformer that provides the required grid services. Moreover, the impact of the CPAT-UPFC during load perturbations on the power system is investigated to further validate its transient and steady-state response. Furthermore, an experimental prototype reveals the operation of the three-phase CPAT-UPFC confirming its stable operation according to the theoretical expectations.

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Speed Controller of Switched Reluctance Motor

ABSTRACT:

Fuzzy logic control has become an important methodology in control engineering. The paper proposes a Fuzzy Logic Controller (FLC) for controlling a speed of SRM drive. The objective of this work is to compare the operation of P& PI based conventional controller and Artificial Intelligence (AI) based fuzzy logic controller to highlight the performances of the effective controller. The present work concentrates on the design of a fuzzy logic controller for SRM speed control. The result of applying fuzzy logic controller to a SRM drive gives the best performance and high robustness than a conventional P & PI controller. Simulation is carried out using matlab simulink.

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Modelling and Simulation of Standalone PV Systems with Battery supercapacitor Hybrid Energy Storage System for a Rural Household

ABSTRACT:

This paper presents the comparison between the standalone photovoltaic (PV) system with battery-supercapacitor hybrid energy storage system (BS-HESS) and the conventional standalone PV system with battery-only storage system for a rural household. Standalone PV system with passive BS-HESS and semi-active BS-HESS are presented in this study. Two control strategies, Rule Based Controller (RBC) and Filtration Based Controller (FBC), are developed for the standalone PV system with semi-active BS-HESS with the aim to reduce the battery stress and to extend the battery lifespan. The simulation results show that the system with semi-active BS-HESS prolongs the battery lifespan by significantly reducing the battery peak current up to 8.607% and  improving the average SOC of the battery up to 0.34% as compared to the system with battery only system.

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