Modeling and Control of Hybrid Power Filter using p-q Theory

 ABSTRACT:

The paper presents design of hybrid active power filter (HAPF) in a three-phase three-wire power system. Design is implemented with instantaneous reactive power theory for control of HAPF in order to mitigate harmonics generated by both non-linear and unbalanced load at the point of common coupling (peC). The p-q Theory enables the source current to be decomposed in αβ0 frame to obtain compensation current for each phase. The hysteresis band current controller is used to generate gating pulses for voltage source inverter (VSI). Over all harmonic reduction is achieved via the proposed control of HAPF and the THD levels are per the IEEE-519 standard. Investigation of proposed scheme is validated by extensive simulations using MATLAB / Simulink Sim-Power System tool box.

KEYWORDS:

1.      Harmonics

2.      Passive Filter

3.      Active Filter

4.      Hybrid Filter

5.      Power Quality

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1: Basic Diagram of SAF

EXPECTED SIMULATION RESULTS:

Fig. 2: Source Current THD (29.9%) without Filter

Fig. 3: Source Current THD (10. I 5%) using Passive Filter

Fig. 4: Source Current THD (4.47%) using Active Filter

Fig. 5: Source Current THD (2.02%) using HAPF

Fig. 6: Compensating Current for Phase a,b and c

Fig. 7: Load Current THD (10.39%) in HAPF

CONCLUSION

This paper highlights the efficacy of HAPF for improving the power quality by eliminating harmonics from power system. The HAPF with a constant power compensation control strategy and hysteresis-band current controller is proposed. A thorough simulation based investigation validates the competency of HAPF among all filters for harmonic mitigation in power system due to current quality problem. The performance examined has demonstrated the efficiency by reducing the source current THD for non-linear load. The THD is well below the specified limit ofIEEE-519 standard.

REFERENCES

[1] A. Baitha and N. Gupta, " A comparative analysis of passive filters for power quality improvement", Int. Conf on Advancements in Power and Energy (TAP Energy), pp. 327-332, 20 IS .

[2] B. Singh and V. Verma, "An improved hybrid filter for compensation of current and voltage harmonics for varying rectifier loads". Int. J. Electrical Power & Energy Systems, Vol. 29, No. 4, pp. 312-xxx, May 2007.

[3] H. Fujita, T. Yamasaki, and H. Akagi, " A hybrid active filters for damping of harmonic resonance in industrial power system," IEEE Trans. on Power Electrics, Vol IS , No. 2, pp. 209-216, 2000.

[4] F.Z. Peng, H. Akagi, and A. Nanbe, " A new approach to harmonic compensation in power systems-A combined system of shunt passive and series active filters," I EEE Trans. on Ind. Appt, Vol. 26, pp. 983-990, Nov. 1990

[5] B. Singh and V. Verma, "Design and Implementation of a Current Controlled Parallel Hybrid Power Filter" Int. Conf on Power Electronics, Drives and Energy Systems, PEDES'06, pp. 1-7, 2006.

Simulation of Power Active Filter using Instantaneous Reactive Power Theory

ABSTRACT:

The paper presents the structure of an active parallel filter for reducing harmonic pollution and reactive power. The active power filter control is based on instantaneous reactive power theory. The authors present the modelling of parallel active filter based on this theory and the simulation results in MATLAB-SIMULINK. The method is based on instantaneous reactive power (TPRI_P).

KEYWORDS:

1.        Distorting regime

2.        Harmonic pollution

3.        Power active filter

4.        Reactive power

5.        Simulation.

SOFTWARE: MATLAB/SIMULINK

BLOCK  DIAGRAM:

Figure 1. Parallel active filter

EXPECTED SIMULATION RESULTS:

Figure 2. The unfiltered current and the current filtered on phase “a”

Figure 3. The active and reactive powers

Figure 4. Current harmonics with three-phase load

Figure 5. Current harmonics with both loads

CONCLUSION

We considered three-phase system with the balanced voltages and presented the conventional method for determining the current value based on the instantaneous active power which was called TPRI_P. The control is made in the system of axes α - β, which use direct and inverse transformation to obtain the equations from one system to another coordinate axes. The currents obtained in the α-β are related to the alternating current power on the network to obtain the compensation current based on current knowledge of the load, in contrast to the conventional method (TPRI_Q) to obtain the controlled values of currents directly. As can be seen in calculations involved only active powers, perfectly measurable.

Also is observed that:

• It produces an increase of the current THD network in the case of the system constant   

   instantaneous power of the energy source.

• Is observed a small fluctuation by active power and reactive power of network in the system

  constant instantaneous power of the energy source.

• Regarding the homopolar power, network evolution is similar in both cases.

REFERENCES

[1]   * * Software Matlab 6.5.

[2]  Arad, S., Popescu, F. G., Pană, L. Improving the energetic efficiency at electric drives compressors of E.M. Lonea. Papers SGEM2013/Conference Proceedings, Vol. Energy and clean technologies, Albena Co., Bulgaria , 2013, 153 - 160.

[3]   Akagi H., Kanazawa Y., Nabae A., Instantaneous reactive power compensators comprising switching devices without energy storage components, IEEE Transactions on Industry Applications, Vol. IA-20, No. 1, May/June 1984, 625-630.

[4]   Akagi H., Kim H., The theory of instantaneous power in three-phase four-wire systems: A comprehensive approach, Conf. Rec. IEEE-IAS Annu. Meeting, 1999, 431-439.

[5]   Popescu, F.G., Arad, S, Marcu, M., Pana, L. Reducing energy consumption by modernizing drives of high capacity equipment used to extract lignite, Papers SGEM2013/Conference Proceedings, Vol.[1]Energy and clean technologies, Albena Co., Bulgaria , 2013, 183 - 190

Impact of Distributed Power Flow Controller to Improve Power Quality Based on Synchronous Reference Frame Method

ABSTRACT

Modern power utilities have to respond to a number of challenges such as growth of electricity demand specially in non-linear loads in power grids, consequently, some policies about the power with a higher quality should be considered. In this paper, distributed power flow controller (DPFC) which is similar to unified power flow controller (UPFC) in structure, is used to mitigate the voltage sag and swell as a power quality issue. Unlike UPFC, the common dc-link in DPFC, between the shunt and series converters is eliminated and three-phase series converter is divided to several single-phase series distributed converters through the transmission line. Also to detect the voltage sags and determine the three single-phase reference voltages of DPFC, the synchronous reference frame method is proposed. Application of DPFC in power quality enhancement is simulated in Matlab/Simulink environment which show the effectiveness of the proposed structure.

KEYWORDS:

1.      FACTS

2.      Power quality

3.      Sag and swell mitigation

4.      Distributed power flow controller.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. The DPFC structure.

Fig. 2. Active power exchange between DPFC converters.

EXPECTED SIMULATION RESULTS:

Fig. 3. Three-phase load voltage sag waveform.

Fig. 4. Mitigation of three-phase load voltage sag with DPFC.

Fig. 5. Three-phase load current swell waveform.

Fig. 6. Mitigation of load current swell with DPFC.

CONCLUSION

The power quality enhancement of the power transmission systems is an vital issue in power industry. In this study, the application of DPFC as a new FACTS device, in the voltage sag and swell mitigation of a system composed of a three-phase source connected to a non-linear load through the parallel transmission lines is simulated in Matlab/Simulink environment. The voltage dip is analyzed by implementing a three-phase fault close to the system load. To detect the voltage sags and determine the three single phase reference voltages of DPFC, the SRF method is used as a detection and determination method. The obtained simulation results show the effectiveness of DPFC in power quality enhancement, especially in sag and swell mitigation.

REFERENCES

[1] J. Faiz, G. H. Shahgholian, and M. Torabian, “Design and simulation of UPFC for enhancement of power quality in transmission lines,” IEEE International Conference on Power System Technology, vol. 24, no. 4, 2010.

[2] A. E. Emanuel and J. A. McNeill, “Electric power quality,” Annu. Rev. Energy Environ, 1997.

[3] I. N. R. Patne and K. L. Thakre “Factor affecting characteristics of voltage sag due to fault in the power system,” Serbian Journal of Electrical engineering. vol. 5, no.1, 2008.

[4] J. R. Enslin, “Unified approach to power quality mitigation,” in Proc. IEEE Int. Symp. Industrial Electronics (ISIE ’98), vol. 1, 1998.

[5] B. Singh, K. Al-Haddad, and A. Chandra, “A review of active filters for power quality improvement,” IEEE Trans. Ind. Electron. vol. 46, no. 5, pp. 960–971, 1999.

[6] M. A. Hannan and A. Mohamed, member IEEE, “PSCAD/EMTDC simulation of unified series-shunt compensator for power quality improvement,” IEEE Transactions on Power Delivery, vol. 20, no. 2, 2005.

A Constant Switching Frequency based Direct Torque Control Method for Interior Permanent Magnet Synchronous Motor Drives

 ABSTRACT

Direct torque control (DTC) is known to be a promising candidate for interior permanent magnet synchronous motor (IPMSM) drives. It provides fast dynamic response and good immunity to parameter variations. However, except for its merits, DTC also suffers from two major problems of variable switching frequency and large torque ripples. Research proposals have been published to solve these problems. Nonetheless, most of the proposals present very complex control algorithms. This paper proposes a constant switching frequency based DTC algorithm for IPMSM drives. It is consisted of only one PI regulator and one triangular-wave carrier. The proposed algorithm reduces the torque ripples to a noticeable extent. In-depth analysis and design guidelines of the proposed controller are given. Simulation and experiment results are provided to verify the effectiveness of the proposed method.

KEYWORDS

1.      Interior permanent magnet synchronous motor

2.      Direct torque control

3.      Constant switching frequency

4.      Torques ripple

5.      Carrier Controller stability.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1 Block diagram of the proposed constant switching frequency control algorithm.

EXPECTED SIMULATION RESULTS

Fig. 2 Response of torque reversal from -4Nm to 4Nm. (a) Classical DTC : reference torque (red), real torque (blue); (b) Proposed constant switching frequency DTC : reference torque (red), real torque (blue).

Fig. 3 Response of speed reversal from -375r/min to 375r/min. (a) Classical DTC : subplot 1: rotor electrical speed, subplot 2: reference torque (red), real torque (blue); (b) Proposed constant switching frequency DTC : subplot 1: rotor electrical speed, subplot 2: reference torque (red), real torque (blue).

Fig. 4 FFT analysis of line current at 375 r/min (a) Classical DTC : subplot 1: line current, subplot 2: Frequency Spectrum of line current; (b) Proposed constant switching frequency DTC : subplot 1 : line current, subplot 2: Frequency Spectrum of line current.

CONCLUSION

This paper presents a simple but effective constant switching frequency based direct torque control method. It significantly reduces the torque ripples and maintains nearly all the merits of the classical DTC. The proposed torque regulator is consisted of one PI controller and one fixed frequency triangular-wave carrier. This benefits the real-time implementation by reducing the computational burden. In-depth modeling and small-signal analysis of the proposed regulator are provided. The design of stable torque regulator by using conventional bode plots is discussed. Both simulation and experimental results are given to verify the performance of the proposed control method.

REFERENCES

[1]   Takahashi and T. Noguchi, “A new quick response and high efficiency control strategy of an induction motor,” IEEE Trans. Ind. Applicat., vol. IA-22, no. 5, pp. 820 - 827, 1986.

[2]   L. Zhong and M.F. Rahman, W.Y. Hu, K.W. Lim, M.A. Rahman, “A direct torque controller for permanent magnet synchronous motor drives,” IEEE Transactions on Energy Conversion, vol. 14, no. 3, pp. 637 - 642, 1999.

[3]   L. Zhong and M.F. Rahman, W. Y. Hu and K.W. Lim, “Analysis of Direct Torque Control in Permanent Magnet Synchronous Motor Drives,” IEEE Trans. Power Electron., vol. 12, no. 3, pp. 528-536, May 1997.

[4]   J.-K. Kang and S.-K. Sul, “Analysis of inverter switching frequency in DTC of induction machine based on hysteresis bands,” IEEE Trans. Ind. Electron., vol. 48, no. 3, pp. 545 - 553, Oct. 2001.

[5]   K. Gulez, A.A. Adam and H. Pastaci, “A Novel Direct Torque Control Algorithm for IPMSM With Minimum Harmonics and Torque Ripples,” IEEE Trans. Mechatron., vol. 12, no. 2, pp. 223 - 227, 2007. 

Direct Torque Control of Induction Motor Drive with Flux Optimization

ABSTRACT

MATLAB / SIMULINK implementation of the Direct Torque Control Scheme for induction motors is presented in this paper. Direct Torque Control (DTC) is an advanced control technique with fast and dynamic torque response. The scheme is intuitive and easy to understand as a modular approach is followed. A comparison between the computed and the reference values of the stator flux and electromagnetic torque is performed. The digital outputs of the comparators are fed to hysteresis type controllers. To limit the flux and torque within a predefined band, the hysteresis controllers generate the necessary control signals. The knowledge about the two hysteresis controller outputs along with the location of the stator flux space vector in a two dimensional complex plane determines the state of the Voltage Source Inverter (VSI). The output of the VSI is fed to the induction motor model. A flux optimization algorithm is added to the scheme to achieve maximum efficiency. The output torque and flux of the machine in the two schemes are presented and compared.

KEYWORDS

1.      Direct Torque Control

2.      Induction Motor

3.      Flux Optimzation

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1: Block Diagram of Conventional DTC Scheme

Figure 2: Block Diagram of the Flux Optimized DTC Scheme

EXPECTED SIMULATION RESULTS

Figure 3: Stator d-q flux space vector without flux optimization

Figure 4: Stator d-q flux space vector with flux optimization

Figure 5: Variation of Stator Flux - Conventional DTC Scheme

Figure 6: Variation of Stator Flux - Optimized DTC Scheme

Figure 7: Variation of Mechanical Speed - Conventional DTC

Scheme

Figure 8: Variation of Mechanical Speed - Optimized DTC

Scheme

Figure 9: Electromagnetic Torque - Conventional DTC

Figure 10: Electromagnetic Torque - Optimized DTC

Figure 11: Percentage Efficiency of Flux Optimized DTC

CONCLUSION

In this paper, DTC for an induction motor drive has been shown along with flux optimization algorithm. DTC is a high performance, robust control structure. A comparative analysis of the two DTC schemes, with and without flux optimization algorithm has been presented. With flux optimization implementation, it is observed that the efficiency of the about 87% has been obtained. MATLAB simulation of a 15 Hp IM drive has been presented to confirm the results.

REFERENCES

[1]   Werner Leonhard. Control of Electric Drives. Springer-Verlag Berlin Heidelberg, 1996.

[2]   F. Blaschke. “The Principle of Field Orientation as Applied to The New Transvector Closed Loop Control System for Rotating Field Machines”. Siemens Review, pages 217–220, 1972.

[3]   K. Hasse. “On The Dynamic Behavior of Induction Machines Driven by Variable Frequency and Voltage Sources”. ETZ Archive, pages 77–81.,1968.

[4]   I. Takahashi and T Nogushi. “A New Quick Reponse and High Efficiency Control Strategy of an Induction Motor”. IEEE Trans. Industry Applications, IA -22:820–827, 1986.

[5]   M. Depenbrock. “Direct Self Control (DSC) of inverter-fed induction machines”. IEEE Trans. Power Electronics, 3(4):420–429, 1988.