An Advanced Current Control Strategy for Three-Phase Shunt Active Power Fi

ABSTRACT:

This paper proposes an advanced control strategy to enhance performance of shunt active power filter (APF). The proposed control scheme requires only two current sensors at the supply side and does not need a harmonic detector. In order to make the supply currents sinusoidal, an effective harmonic compensation method is developed with the aid of a conventional proportional-integral (PI) and vector PI controllers. The absence of the harmonic detector not only simplifies the control scheme but also significantly improves the accuracy of the APF, since the control performance is no longer affected by the performance of the harmonic tracking process. Furthermore, the total cost to implement the proposed APF becomes lower, owing to the minimized current sensors and the use of a four-switch three-phase inverter. Despite the simplified hardware, the performance of the APF is improved significantly compared to the traditional control scheme, thanks to the effectiveness of the proposed compensation scheme. The proposed control scheme is theoretically analyzed, and a 1.5-kVA APF is built in the laboratory to validate the feasibility of the proposed control strategy.

KEYWORDS:

1.      Active power filters (APFs)

2.       Harmonic current compensation

3.       Power quality

4.       Resonant controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Typical control scheme of a shunt APF.

 Fig. 2. Structure of the proposed control scheme for three-phase shunt APF.

 EXPECTED SIMULATION RESULTS:

Fig. 3. Steady-state performance with PI current controller under RL load.

Fig. 4. Steady-state performance with proposed control scheme under RL load.

Fig. 5. Dynamic responses of proposed control scheme under RL load

variations: (a) load applied (b) load changed.

Fig. 6. Steady-state performance with proposed control scheme under RLC load.

Fig. 7. Dynamic responses of proposed control scheme under RLC load

variations: (a) load applied (b) load changed.

Fig. 8. Steady-state performance of the proposed control scheme under

distorted supply voltage condition with (a) RL load and (b) RLC load.

Fig. 9. Steady-state performances of the four-switch APF with (a) RL load

and (b) RLC load.

                                                                                                                                                                                                 CONCLUSION:

In this paper, an advanced control strategy for the three-phase shunt APF was proposed. The effectiveness of the proposed control strategy was verified through various experimental tests, where the proposed control strategy presented good steady-state performance with nonlinear RL and RLC loads as well as good dynamic response against load variations: the supply current is almost perfect sinusoidal and in-phase with the supply voltage even under the distorted voltage condition. The experimental results verified that the absence of a harmonic detector results in faster transient responses as well as assures notches free in steady-state performances of the supply current. Moreover, we also confirmed that the FSTPI can be used to implement the APF without any degradation in the APF performance. In all of the experiments, THD factor of the supply current was reduced to less than 2%, which completely comply with the IEEE-519 and IEC-61000-3-2 standards.

REFERENCES:

[1] Recommended Practice for Harmonic Control in Electric Power Systems, IEEE Std. 519-1992, 1992.

[2] Limits for Harmonic Current Emission, IEC 61000-3-2, 2001.

[3] H. Akagi, “New trends in active filters for power conditioning,” IEEE Trans. Ind. Appl., vol. 32, no. 2, pp. 1312–1332, Nov./Dec. 1996.

[4] F. Z. Peng, “Application issues of active power filters,” IEEE Ind. Appl. Mag., vol. 4, no. 5, pp. 21–30, Sep./Oct. 1998.

[5] H. Akagi, E. H. Watanabe, and M. Aredes, Instantaneous Power Theory and Applications to Power Conditioning, M. E. El-Hawari, Ed.New York: Wiley, 2007.           

Review of Vector Control Strategies for Three Phase Induction Motor Drive

ABSTRACT:

Induction motor drives are at the heart of modern industrial and commercial applications. With conventional control techniques, induction motor drives have shown less than expected dynamic performance. With vector control techniques emerging as potential replacement in induction motor drives, this paper aims at highlighting various vector control strategies. Direct and indirect vector controls along with sensorless vector control are presented. Various speed control techniques are presented through the use of conventional controllers and Intelligent Controllers. A critical analysis and comparison is made with other control strategies.

KEYWORDS:

1.      Field oriented control

2.      Sensorless vector control

3.      Direct torque control

4.      Modulation

5.      Parameter estimation

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. Block diagram of general vector control scheme

 CONCLUSION:

 The use of vector control has been presented for Induction motor drives. A number of vector control schemes have been presented with merits and demerits of each. Different controllers (conventional and intelligent controllers) have been used in various schemes of vector control strategy. Potentially DTC is proving to be superior to other vector control techniques. Contrast to field oriented controller, it is more robust, does not require any transformation, current controller, or rotor position measurement. However, an improvement in torque ripples is the demand of this scheme. Sensorless vector control offers low cost and more reliability, but operation of this scheme in low speed region is one of its biggest drawbacks.

REFERENCES:

[1] Bimal. K.Bose (2002) – “Modern Power Electronics & AC Drives”, Prentice Hall, ISBN 0-13-016743-6

[2] Rupprecht Gabriel. Werner Leonhard, and Craig J. Nordby, “Field- Oriented Control of a Standard AC Motor Using Microprocessors”, IEEE Transactions On Industrial Applications, Vol. IA-16, No. 2, pp. 186-192, March/April 1980.

[3] Masato Koyama, Masao Yano, Isao Kamiyama, And Sadanari Yano, “Microprocessor-Based Vector Control System For Induction Motor Drives With Rotor Time Constant Identification Function”, IEEE Transactions on Industry Applications, Vol. IA-22, No. 3, pp. 453-459, May/June 1986.

[4] Ramu Krishnan, and Aravind S. Bharadwaj, “A review of parameter sensitivity and adaptation in indirect vector controlled induction motor drive systems”, IEEE transactions on power electronics, Vol. 6, No. 1, pp.695-703, October 1991.

[5] Luis J. Garces, “Parameter Adaption for the Speed-Controlled Static AC Drive with a Squirrel-Cage Induction Motor”, IEEE Transactions on Industry Applications, Vol. IA-16, no. 2, pp. 173 -178, March/April 1980.

Phase Angle Calculation Dynamics of Type-4 Wind Turbines in rms Simulations during Severe Voltage Dips

 ABSTRACT:

To conduct power system simulations with high shares of wind energy, standard wind turbine models, which are aimed to be generic rms models for a wide range of wind turbine types, have been developed. As a common practice of rms simulations, the power electronic interface of wind turbines is assumed to be ideally synchronised, i.e. grid synchronisation (e.g. phase locked loop (PLL)) is not included in simplified wind turbine models. As will be shown in this study, this practice causes simulation convergence problems during severe voltage dips and when the loss of synchronism occurs. In order to provide the simulation convergence without adding complexity to the generic models, a first-order filtering approach is proposed as a phase angle calculation algorithm in the grid synchronisation of the rms type-4 wind turbine models. The proposed approach provides robustness for the simulation of large-scale power systems with high shares of wind energy.

SOFTWARE: MATLAB/SIMULINK

 TEST NETWORK:

Fig. 1 Test network for the fault cases

 EXPECTED SIMULATION RESULTS:

 Fig.2 Simulation results with a PI-based PLL method and the proposed LPF method, during a severe fault (VPoC = 0.1%) (a) VPoC (pu), (b) Active current (Id) reference (solid grey), actual in PLL case (dashed grey) and actual in LPF case (dotted black) (pu), (c) Reactive current (Iq) reference (solid grey), actual in PLL case (dashed grey) and actual in LPF case (dotted black) (pu), (d) WT terminal voltage angle (wrap between ±180) in PLL case (dashed grey) and in LPF case (dotted black) (degrees)

Fig. 3 Simulation results of the proposed LPF method with threshold triggering function during a severe fault (VPoC = 0.1%) (a)VPoC (pu), (b) Active current (Id) reference (solid grey) and actual (dotted black) (pu), (c) Reactive current (Iq) reference (solid grey) and actual (dotted black) (pu), (d) WT terminal voltage angle (wrap between ±180) (degrees)

CONCLUSION:

Owing to the large share of wind power in power systems of certain countries, especially in Europe, the need of power system analysis with WPPs arises. WT and WPP models have been developed by the academia and WT manufacturers, which are chosen as rms models in order to provide computational simplicity and speed, considering large-scale simulations. In addition, standards for the developed WT and WPP models have been developed by IEC and WECC working groups. As a common requirement of the grid codes, the developed models are utilised for short-term voltage stability and fault ride-through studies. The conventional method of instantaneous phase angle calculation, i.e. ideal grid synchronisation, performs well with moderately low voltage faults. However, it is shown that the physical fact of the LOS of WT converters during severe voltage dips is observed to cause simulation non-convergence problems with the instantaneous angle calculation method in rms simulations.

In this paper, a first-order LPF is proposed as angle calculation method in converter-based WTs in order to solve the nonconvergence errors during severe voltage faults. The proposed LPF method is shown in order to solve the non-convergence errors even for solid faults (i.e. a zero impedance three-phase fault). In addition, implementing a threshold triggering function to activate the LPF-based calculation only during severe voltage dips avoided any possible impairment during healthy steady-state operations. Moreover, the frequency deviation due to the LOS problem, which needs to be solved with additional control methods, is shown to be represented with the LPF method. Hence, the proposed LPF method gives the possibility to detect if the WPP experiences the LOS and hence to solve it.

The recently published IEC 61400-27-1 WTs electrical simulation models standard [1] has adopted the proposed idea of utilising a first-order LPF as phase angle calculation in rms simulations, which helps to obtain robust simulations, especially when a large-scale (e.g. Pan-European) power system with high share of wind power is simulated and analysed.

REFERENCES:

[1] IEC 61400-27-1 Ed. 1: ‘Wind turbines – part 27-1: electrical simulation models – wind turbines’, February 2015

[2] Asmine, M., Brochu, J., Fortmann, J., et al.: ‘Model validation for wind turbine generator models’, IEEE Trans. Power Syst., 2011, 26, (3), pp. 1769– 1782

[3] ENTSO-E: ‘Network code for requirements for grid connection applicable to all generators (NC RfG)’, European Network of Transmission System Operators for Electricity ENTSO-E, 2015

[4] Goksu, O., Teodorescu, R., Bak, C.L., et al.: ‘Instability of wind turbine converters during current injection to low voltage grid faults and PLL frequency based stability solution’, IEEE Trans. Power Syst., 2014, 29, (4), pp. 1683–1691

[5] Erlich, I., Shewarega, F., Engelhardt, S., et al.: ‘Effect of wind turbine output current during faults on grid voltage and the transient stability of wind parks’. IEEE Power and Energy Society General Meeting, July 2009, pp. 1–8

PWAM Controlled Quasi-Z Source Motor Drive

 ABSTRACT:

This paper proposes a novel pulse-width-amplitude modulation (PWAM) method for three-phase quasi-Z source inverter system in motor drive application. It is demonstrated that it operates at only 1/3 switching frequency of traditional PWM methods, with less harmonic distortion. As a result, switching actions and losses are also reduced significantly. With the proposed modulation, the required capacitance is reduced greatly, which makes a system of smaller volume and lighter weight. Compared to traditional PWM methods, the higher efficiency and better reliability are confirmed in PWAM controlled motor drive system. The motor drive with the proposed hybrid PWAM modulation method presents good performance in simulation. Theoretical analysis is provided to verify the inverter efficiency and design improvements.

KEYWORDS:

1.      Quasi-Z-source inverter

2.      Pulse-width-amplitude modulation

3.      Motor drive

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1. Quasi-Z source inverter based motor drive [8].

Fig. 2. Topology in the second sector.

EXPECTED SIMULATION RESULTS:

Fig. 3. Outcomes of rotation speed r, current i_a and torque T_m of motor (f=30 Hz).

Fig. 4. Simulation results of three-phase qZSI when using PWAM method. (a) qZS capacitor voltages v_c1and v_c2; (b) qZS inductor currents i_L1 and i_L2; (c) qZSI’s dc-link voltage v_pn; (d) qZSI’s output line to line voltage v_ab(f=30 Hz).

Fig. 5. Simulation results of three-phase qZSI when using PWAM method. (a) qZS capacitor voltages v_c1and v_c2 ; (b) qZS inductor currents i_L1 and i_L2; (c) qZSI’s dc-link voltage v_pn; (d) qZSI’s output line to line voltage v_ab(f=50 Hz).

Fig. 6. Outcomes of rotation speed r, current i_a and torque T_m of motor (f=50 Hz).

CONCLUSION:

In this paper, a novel modulation method for three-phase qZSI motor drive was introduced. The qZSI allows dc-link 6ɷ voltage ripples, as a result that the required qZS inductance and capacitance are reduced significantly. Besides, compared to traditional SPWM, only one third of the switches are doing switching actions, which reduced the number of switching time and loss significantly. By using the proposed PWAM modulation method, the motor drive operates well and efficiently.

REFERENCES:

[1] H. W. van der Broeck, H. C. Skudelny, G. V. Stanke, “Analysis and Realization of a Pulsewidth Modulator Based on Voltage Space Vectors,” IEEE Transactions on Industry Applications, 1988, pp. 142- 150.

[2] H. Abu-Rub, M. Malinowski, K. Al-Haddad: Power Electronics for Renewable Energy Systems, Transportation and Industrial Applications, Hoboken, NJ: John Wiley & Sons Ltd., 2014.

[3] C. Y. Leong, N. P. van der Duijn Schouten, P. D. Malliband, R. A. McMahon, “A Comparison of Power Losses for Small Induction Motor Drives Adopting Squarewave and Sinusoidal PWM Excitation,” Second International Conference on Power Electronics, Machines and Drives (PEDG), 2004, pp. 286-290.

[4] H. Zhang, B. Ge, Y. Liu, D. Sun, “A Hybrid Modulation Method for Single-Phase Quasi-Z Source Inverter,” in 2014 IEEE Energy Conversion Congress and Exposition (ECCE), pp.4444-4449, 2014.

[5] D. Sun, B. Ge, X. Yan, D. Bi, H. Zhang, Y. Liu, H. Abu-Rub, L. BenBrahim, F.Z. Peng, "Modeling, impedance design, and efficiency analysis of quasi-Z source module in cascaded multilevel photovoltaic power system," IEEE Transactions on Industrial Electronics, vol.61, no.11, pp.6108-6117, Nov. 2014.

Single Stage Solar PV Fed Brushless DC Motor Driven Water Pump

ABSTRACT:

In order to optimize the solar photovoltaic (PV) generated power using a maximum power point tracking (MPPT) technique, a DC-DC conversion stage is usually required in solar PV fed water pumping which is driven by a brushless DC (BLDC) motor. This power conversion stage leads to an increased cost, size, complexity and reduced efficiency. As a unique solution, this work addresses a single stage solar PV energy conversion system feeding a BLDC motor-pump, which eliminates the DC-DC conversion stage. A simple control technique capable of operating the solar PV array at its peak power using a common voltage source inverter (VSI), is proposed for BLDC motor control. The proposed control eliminates the BLDC motor phase current sensors. No supplementary control is associated for the speed control of motor-pump and its soft start. The speed is controlled through the optimum power of solar PV array. The suitability of proposed system is manifested through its performance evaluation using MATLAB/Simulink based simulated results and experimental validation on a developed prototype, under the practical operating conditions.

KEYWORDS:

1.      MPPT

2.       Solar PV array

3.      BLDC motor

4.       Water pump

5.      VSI

6.      Soft starting

7.      Speed control

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1 Proposed water pumping based on a single stage solar PV energy conversion system.

 EXPECTED SIMULATION RESULTS:

 Fig.2 Steady state and starting performance of (a) PV array and (b) motor pump, of proposed system at 1 kW/m².

Fig.3 Steady state and starting response of (a) PV array and (b) motor-pump, of proposed system at 200 W/m².

Fig.4 Dynamic performance of (a) PV array and (b) BLDC motor Pump ,of Proposed  water pumping system.

Fig. 5 Responses of (a) PV array and (b) BLDC motor, under partial shading

CONCLUSION:

The proposed BLDC motor driven water pumping based on a single stage solar PV generation has been validated through a demonstration of its various steady state, starting and dynamic performances. The system has been simulated using the MATLAB toolboxes, and implemented on an experimental prototype. The topology of the proposed system has provided a DC-DC converter-less solution for PV fed brushless DC motor driven water pumping. Moreover, the motor phase current sensing elements have been eliminated, resulting in a simple and cost-effective drive. The other desired functions are the speed control without any additional circuit and a soft start of the motor-pump. A detailed comparative analysis of the proposed and the existing topologies has ultimately manifested the superiority of the proposed work.

REFERENCES:

[1] C. Jain and B. Singh, “An Adjustable DC Link Voltage Based Control of Multifunctional Grid Interfaced Solar PV System,” IEEE J. Emerg. Sel. Topics Power Electron., Early Access.

[2] A. A. A. Radwan and Y. A. R. I. Mohamed, “Power Synchronization Control for Grid-Connected Current-Source Inverter-Based Photovoltaic Systems,” IEEE Trans. Energy Convers., vol. 31, no. 3, pp. 1023-1036, Sept. 2016.

[3] P. Vithayasrichareon, G. Mills and I. F. MacGill, “Impact of Electric Vehicles and Solar PV on Future Generation Portfolio Investment,” IEEE Trans. Sustain. Energy, vol. 6, no. 3, pp. 899-908, July 2015.

[4] A. K. Mishra and B. Singh, “A single stage solar PV array based water pumping system using SRM drive,” IEEE Ind. Appl. Soc. Annu. Meeting, Portland, OR, 2016, pp. 1-8.

[5] S. Jain, A.K. Thopukara, R. Karampuri and V.T. Somasekhar, “A Single-Stage Photovoltaic System for a Dual-Inverter-Fed Open-End Winding Induction Motor Drive for Pumping Applications,” IEEE Trans. Power Electron., vol. 30, no. 9, pp. 4809 - 4818, Sept. 2015.

BLDC Motor Driven Solar PV Array Fed Water Pumping System Employing Zeta Converter

ABSTRACT:

This paper proposes a simple, cost effective and efficient brushless DC (BLDC) motor drive for solar photovoltaic (SPV) array fed water pumping system. A zeta converter is utilized in order to extract the maximum available power from the SPV array. The proposed control algorithm eliminates phase current sensors and adapts a fundamental frequency switching of the voltage source inverter (VSI), thus avoiding the power losses due to high frequency switching. No additional control or circuitry is used for speed control of the BLDC motor. The speed is controlled through a variable DC link voltage of VSI. An appropriate control of zeta converter through the incremental conductance maximum power point tracking (INC-MPPT) algorithm offers soft starting of the BLDC motor. The proposed water pumping system is designed and modeled such that the performance is not affected under dynamic conditions. The suitability of proposed system at practical operating conditions is demonstrated through simulation results using MATLAB/ Simulink followed by an experimental validation.

KEYWORDS:

1.      BLDC motor

2.      SPV array

3.      Water pump

4.      Zeta converter

5.      VSI

6.      INC-MPPT

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1 Configuration of proposed SPV array-Zeta converter fed BLDC motor drive for water pumping system.

 EXPECTED SIMULATION RESULTS:

Fig.2 Performances of the proposed SPV array based Zeta converter fed BLDC motor drive for water pumping system (a) SPV array variables, (b) Zeta converter variables, and (c) BLDC motor-pump variables.

CONCLUSION:

The SPV array-zeta converter fed VSI-BLDC motor-pump for water pumping has been proposed and its suitability has been demonstrated by simulated results using MATLAB/Simulink and its sim-power-system toolbox. First, the proposed system has been designed logically to fulfil the various desired objectives and then modelled and simulated to examine the various performances under starting, dynamic and steady state conditions. The performance evaluation has justified the combination of zeta converter and BLDC motor drive for SPV array based water pumping. The system under study availed the various desired functions such as MPP extraction of the SPV array, soft starting of the BLDC motor, fundamental frequency switching of the VSI resulting in a reduced switching losses, reduced stress on IGBT switch and the components of zeta converter by operating it in continuous conduction mode and stable operation. Moreover, the proposed system has operated successfully even under the minimum solar irradiance.

REFERENCES:

[1] M. Uno and A. Kukita, “Single-Switch Voltage Equalizer Using Multi- Stacked Buck-Boost Converters for Partially-Shaded Photovoltaic Modules,” IEEE Transactions on Power Electronics, no. 99, 2014.

[2] R. Arulmurugan and N. Suthanthiravanitha, “Model and Design of A Fuzzy-Based Hopfield NN Tracking Controller for Standalone PV Applications,” Electr. Power Syst. Res. (2014). Available: http://dx.doi.org/10.1016/j.epsr.2014.05.007

[3] S. Satapathy, K.M. Dash and B.C. Babu, “Variable Step Size MPPT Algorithm for Photo Voltaic Array Using Zeta Converter – A Comparative Analysis,” Students Conference on Engineering and Systems (SCES), pp.1-6, 12-14 April 2013.

[4] A. Trejos, C.A. Ramos-Paja and S. Serna, “Compensation of DC-Link Voltage Oscillations in Grid-Connected PV Systems Based on High Order DC/DC Converters,” IEEE International Symposium on Alternative Energies and Energy Quality (SIFAE), pp.1-6, 25-26 Oct. 2012.

[5] G. K. Dubey, Fundamentals of Electrical Drives, 2nd ed. New Delhi, India: Narosa Publishing House Pvt. Ltd., 2009.