An Improved Control Algorithm of Shunt Active Filter for Voltage Regulation, Harmonic Elimination, Power-Factor Correction, and Balancing of Nonlinear Loads

ABSTRACT:  

This paper deals with an implementation of a new control algorithm for a three-phase shunt active filter to regulate load terminal voltage, eliminate harmonics, correct supply power-factor, and balance the nonlinear unbalanced loads. A three-phase insulated gate bipolar transistor (IGBT) based current controlled voltage source inverter (CC-VSI) with a dc bus capacitor is used as an active filter (AF). The control algorithm of the AF uses two closed loop PI controllers.

The dc bus voltage of the AF and three-phase supply voltages are used as feed back signals in the PI controllers. The control algorithm of the AF provides three-phase reference supply currents. A carrier wave pulse width modulation (PWM) current controller is employed over the reference and sensed supply currents to generate gating pulses of IGBT’s of the AF. Test results are presented and discussed to demonstrate the voltage regulation, harmonic elimination, power-factor correction and load balancing capabilities of the AF system.

KEYWORDS:

  1. Active filter
  2. Harmonic compensation
  3. Load balancing
  4. Power-factor correction
  5. Voltage regulation

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:


Fig. 1. Fundamental building block of the active filter.

 EXPECTED SIMULATION RESULTS:

Fig. 2. Performance of the AF system under switch IN and steady state conditions with a three-phase nonlinear load.

Fig. 3. Steady state response of the AF for voltage rgulation and harmonic elimination with a three-phase nonlinear load.

Fig. 4. Steady state response of the AF for voltage regulation, harmonic elimination, and load balancing with a single-phase nonlinear load.

Fig. 5. Switch IN response of the AF for voltage regulation, harmonic elimination with a three-phase nonlinear load.

Fig. 6. Switch IN response of the AF for voltage regulation, harmonic elimination and load balancing with a single-phase nonlinear load.

Fig. 7. Dynamic response of the AF for voltage regulation, harmonic elimination, and load balancing under the load change from three-phase to single-phase.

Fig. 8. Dynamic response of the AF for voltage regulation, harmonic elimination, and load balancing under the load change from single-phase to three-phase.

Fig. 9. Steady state response of the AF for power-factor correction, harmonic elimination with a three-phase nonlinear load.

Fig. 10. Steady state response of the AF for power-factor correction, harmonic elimination, and load balancing with a single-phase nonlinear load.

Fig. 11. Switch IN response of the AF for power-factor correction and harmonic elimination with a three-phase nonlinear load.

Fig. 12. Switch IN response of the AF for power-factor correction, harmonic elimination, and load balancing with a single-phase nonlinear load.

 CONCLUSION:

 An improved control algorithm of the AF system has been implemented on a DSP system for voltage regulation/power-factor correction, harmonic elimination and load balancing of nonlinear loads. Dynamic and steady state performances of the AF system have been observed under different operating conditions of the load. The performance of the AF system has been found to be excellent. The AF system has been found capable of improving the power quality, voltage profile, power-factor correction, harmonic elimination and balancing the nonlinear loads.

The proposed control algorithm of the AF has an inherent property to provide a self-supporting dc bus and requires less number of current sensors resulting in an over all cost reduction. It has been found that for voltage regulation and power-factor correction to unity are two different things and can not be achieved simultaneously.

However, a proper weight-age to in-phase and quadrature components of the supply current can provide a reasonably good level of performance and voltage at PCC can be regulated with a leading power-factor near to unity. It has been found that the AF system reduces harmonics in the voltage at PCC and the supply currents well below the mark of 5% specified in IEEE-519 standard.

REFERENCES:

[1] L. Gyugyi and E. C. Strycula, “Active AC power filters,” in Proc.IEEE-IAS Annu. Meeting Record, 1976, pp. 529–535.

[2] T. J. E. Miller, Reactive Power Control in Electric Systems. Toronto,Ont., Canada: Wiley, 1982.

[3] J. F. Tremayne, “Impedance and phase balancing of main-frequency induction furnaces,” Proc. Inst. Elect. Eng. B, pt. B, vol. 130, no. 3, pp. 161–170, May 1983.

[4] H. Akagi, Y. Kanazawa, and A. Nabae, “Instantaneous reactive power compensators comprising switching devices without energy storage components,” IEEE Trans. Ind. Applicat., vol. IA-20, pp. 625–630, May/June 1984.

[5] T. A. Kneschki, “Control of utility system unbalance caused by single-phase electric traction,” IEEE Trans. Ind. Applicat., vol. IA-21, pp. 1559–1570, Nov./Dec. 1985.

Single Phase Series Active Power Filter Based on 15-Level Cascaded Inverter Topology

ABSTRACT:

A topology of series active power filter (SAP F) based on a single phase half-bridge cascaded multilevel invert er is proposed in order to compensate voltage harmonics of the load connected to the point of common coupling (P CC). This paper presents the main parts of the invert er and The proposed invert er with the simple control easily obtains any voltage reference. Therefore, the invert er acts as a harmonic source when the reference is a non-sinusoidal signal.

prototype

A prototype of 15-level invert er based SAP F is manufactured without using a parallel passive filter (PP F) because it is intended to represent the compensation capability of the SAP F by itself. The load connected to P CC whose voltage is non-sinusoidal is filtered both in simulation and experimental studies. The validity of the proposed invert er based SAP F is verified by simulation as well as experimental study. Both simulation and experimental results show that the proposed multilevel invert er is suitable for SAP F applications.

 

CIRCUIT DIAGRAM:

Figure 1. The basic configuration of the proposed system.

EXPECTED SIMULATION RESULTS:

Figure 2. Simulation results – Set I a) V p cc and V h P CC before compensation (50 V I div), b) invert er and load voltage after compensation (50 V I div).

Figure 3. Simulation results – Set 2 a) V p cc and V”p cc before compensation (50 V l div), b) invert er and load voltage after compensation (50 V I div).

CONCLUSION:

This paper proposes a single phase half-bridge cascaded multi level invert er based SAP F. The multi level invert er topology and operation principle is introduced and With the proposed topology, the number of output levels can easily be increased. Switching angles of the semiconductor devices used in the invert er are also obtained by a simple method, moreover A SAP F with the proposed invert er topology is simulated under different harmonic distortion levels of P CC.

aim

The aim of the simulation is to compensate the load voltage harmonics connected to P Cc. In addition to the simulations, the proposed SAP F prototype is designed and Using this prototype, experimental study is also performed. Microchip d s PIC 30 F 6010 is preferred as a controller in this prototype, because it is commercially available and inexpensive micro controller. The presentable results of the proposed system are summarized as follows;

results

  • The TH D values obtained from simulation study is similar to experimental results and the results of simulation and experimental studies demonstrate the accuracy of the simulation study.
  • The TH D values after compensation is reduced to 2.88% and 3.07% by using the proposed invert er based SAP F and After compensation, the waveform of load voltage is almost sinusoidal.
  • A highly distorted sinusoidal waveform with a TH D value of 24.12% is compensated with the proposed invert er based SAP F and the TH D value is reduced to 3.07%, with This it is shown that the proposed invert er is suitable for SAP F applications.

Both simulation and experimental studies show the validity of the proposed invert er as a SAP F.

REFERENCES:

[1] M. 1. M. Mon t e r o, E. R. Ca d a val, F. B. Gonzalez, “Comparison of control strategies for shunt active power filters in three-phase four wire systems”, IEEE Trans. Power Electron., , 22, (I), pp. 229- 236, 2007.

[2] F. Z. P e n g, H. A k a g i, and A. Na b a e, ” A new approach to harmonic compensation in power systems-A combined system of shunt passive and series active filters,” IEEE Trans. Ind. A pp l. , Vol. 26, No. 6, pp. 983- 990, N o v.l Dec. 1990.

[3] Z. Wang, Q. Wang, W. Y a o, and 1. Li u, “A series active power filter adopting hybrid control approach,” IEEE Trans. Power Electron. , Vol. 16, No. 3, pp. 301- 310, May 2001.

[4] H. Aka g i, ‘Trends in active power line conditioners,” IEEE Trans. Power Electron. , Vol. 9, No. 3, pp. 263- 268, May 1994.

[5] M. E I-H ab r o u k, M. K. D a r wish, and P. Me h ta, “Active power filters : A review,” l E E Elect r. Power App l., Vol. 147, No. 5, pp. 403-413, Sep.2000.

A Novel 7-Level Cascaded Inverter for Series Active Power Filter

ABSTRACT:

Harmonic voltage compensation of the load connected to the point of common coupling (PCC) by using a series of active power filter (SAPF) based on a single phase cascaded multilevel inverter is proposed. The proposed multilevel inverter are presented in detail. The inverter has the ability of acting as a harmonic source when the reference is a non-sinusoidal signal. To achieve this, a simple control technique is performed with the proposed inverter. A prototype of 7-level inverter based SAPF is manufactured without using a parallel passive filter (PPF) because it is designed to show SAPF own compensation capacity alone. Filtering ability of the SAPF is shown both in simulation and experimental studies. The validity of the proposed inverter based SAPF is verified by simulation as well as experimental study. The results show that the proposed multi-level inverter is suitable for SAPF applications.

KEYWORDS:

  1. Active power filter
  2. Multilevel inverter
  3. Harmonic compensation
  4. Half-bridge cascaded
  5. Power quality

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. The scheme of the proposed system.

EXPECTED SIMULATION RESULTS:

 

 (a) Simulation result (50 V/div), (5 ms/div)

Fig. 2. The waveform of VPCC before compensation

(a) Simulation result (50 V/div), (5 ms/div)

Fig. 3. The waveforms of the load voltage and the proposed inverter voltage after compensation.

 CONCLUSION:

This paper proposes a single phase cascaded inverter based SAPF. The 7-level inverter topology and operation principle is introduced. With the proposed topology, the number of output levels can easily be increased. Switching signals of the semiconductor devices used in the inverter are also obtained by a simple method. A SAPF with the proposed inverter topology is simulated.The aim of the simulation is to compensate the load voltage harmonics connected to PCC. In addition to the simulation, the proposed SAPF prototype is designed. Using this prototype, experimental study is performed. Simulation and experimental results similar each other proves the accuracy of the analysis. The load waveform that is highly distorted with a THD value of 24.12% is compensated with the proposed inverter based SAPF and the THD value is reduced to 3.80% in experimental study. This shows that the proposed inverter is suitable for SAPF applications.

REFERENCES:

[1] M. I. M. Montero, E. R. Cadaval, F. B. Gonzalez, “Comparison of control strategies for shunt active power filters in three-phase four-wire systems”, IEEE Trans. Power Electron., vol. 22, no. 1, pp. 229–236, 2007.

[2] F. Z. Peng, H. Akagi, and A. Nabae, “A new approach to harmonic compensation in power systems—A combined system of shunt passive and series active filters,” IEEE Trans. Ind. Appl., vol. 26, no. 6, pp. 983– 990, Nov./Dec. 1990.

[3] Z. Wang, Q. Wang, W. Yao, and J. Liu, “A series active power filter adopting hybrid control approach,” IEEE Trans. Power Electron., vol. 16, no. 3, pp. 301–310, May 2001.

[4] H. Akagi, “Trends in active power line conditioners,” IEEE Trans. Power Electron., vol. 9, no. 3, pp. 263–268, May 1994.

[5] M. El-Habrouk, M. K. Darwish, and P. Mehta, “Active power filters: A review,” IEE Electr. Power Appl., vol. 147, no. 5, pp. 403–413, Sep. 2000.