Performance Enhancement of Shunt Active Power filter using a Kalman Filter based H∞ Control Strategy Simulation Projects

 

ABSTRACT

This paper proposes a Kalman filter (KF) based H∞ control scheme for a three phase shunt active power filter (SAPF) system. For the current control loop, a H∞ controller is designed with a mixed sensitivity approach for achieving stability and high disturbance rejection in the SAPF system. A new current reference scheme is also proposed that employs KF to avoid synchronization circuit and proportional integral (PI) controller loop resulting in a reliable and cost-effective SAPF system. This reference scheme can self-regulate the dc-link voltage by a fast and adaptive estimation of the source reference current with power system perturbations raised in source or load sides. The efficacy of the proposed KF-H∞ control algorithm is evaluated through comparison with an existing PI and PI plus vector PI (PI-PIVPI) algorithm and then validated with experimental studies pursued using a dSPACE1104. From the obtained experimental results, it is observed that the proposed SAPF significantly outperforms the existing PI-PIVPI in terms of exhibiting robustness to modeling uncertainties and insensitivity to grid perturbations such as harmonics, measurement noise and phase angle jump. Thus, the power quality improvement is achieved in terms of perfect current harmonics cancellation as well as power factor improvement.

KEYWORDS:

  1. Active power filter
  2. Self-regulate
  3. Robustness
  4. Power quality
  5. Harmonics cancellation
  6. Power factor improvement

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig.1 Proposed SAPF Control Scheme

 

EXPECTED SIMULATION RESULTS:

Fig.2 Test Case-1:(a) three-phase supply voltages, (b) three-phase load currents

Fig.3 Test Case-1:(a) three-phase source reference currents in proposed method, (b) three-phase compensating currents in proposed method, (c) dc link voltage in proposed method

Fig.4. Test Case-1: Harmonic spectra of (a) phase-a load current, (b) phase a source current in the Proposed method, and (c) phase-a source current in the Existing method

Fig.5.Test Case-2: Waveforms of three phase source currents, (i) Proposed Method, (ii) Existing Method

Fig. 6. Test Case-2: Harmonic spectra of (a) phase-a source current in Proposed Method, and (b) phase-a source current in Existing Method

Fig.7.Test Case -3: (a) three phase load currents, (b) dc-link voltage in proposed method

Fig. 8 Test Case -3: (a) Waveforms of three phase compensating currents, (b) Waveforms of three phase source currents , (i) Proposed Method, (ii) Existing Method

Fig. 9 Test Case-3: Harmonic spectra of (a) phase-a load current, (b) phase-a source current in Proposed Method, and (c) phase-a source current in Existing Method

Fig. 10.Test Case-4: (a) Three phase supply voltages, (b) Three phase load currents, (c) Three phase compensating currents in Proposed Method

Fig. 11. Case-4: Waveforms of three phase source currents and dc-link voltage, (i) Proposed Method, (ii) Existing Method

Fig. 12. Test Case-4: Harmonics spectra of (a) phase-a load current, (b) phase a source current in Proposed Method, and (c) phase-a source current in Existing Method

Fig. 13. Test Case-5: Harmonics spectra of (a) phase-a load current, (b) phase a source current in Proposed Method, and (c) phase-a source current in Existing Method

CONCLUSION

In this paper, a H∞ controller with a new reference current estimation scheme based on KF has been proposed for a SAPF. This reference generation scheme is simple yet reliable and self regulator of dc-link voltage without having a PI controller. Only source current sensors are sufficient to determine the reference current, which decreases the effective cost of SAPF implementation. Further, H∞ current controller is designed with a proper selection of weighting functions to specify the robustness, control effort performance and error tracking performance of SAPF. Finally, the effectiveness of the proposed KF-H∞ control strategy was verified through various experimental tests, where the proposed control strategy presented good steady state as well as dynamic performance against supply or load variations. Generally power line uncertainties such as fluctuation of load, variation of system parameter, sudden failure of power system components and sensor nonlinearities degrade the reliability and efficiency of the SAPF system. Moreover, grid perturbations such as harmonics, measurement noise and phase angle jump are responsible for power quality deterioration. Hence, the objective of designing a robust control strategy in SAPF is achieved by accommodating all the possible perturbations occurring in the power system. From the experimental results, it is also observed that the proposed KF-H∞ control approach to design a SAPF is found to be robust in face parametric uncertainties due to grid perturbations yielding improvement in power quality more effectively in terms of tracking error reduction and efficient current harmonics mitigation.

REFERENCES

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  • F. Zobaa, ―Optimal multiobjective design of hybrid active power filters considering a distorted environment,‖ IEEE Trans. on Ind. Electron., vol. 61, no. 1, pp. 107-113, Jan. 2014.
  • Hao, X. Yang and T. Liu, “A sliding-mode controller with multiresonant sliding surface for single-phase grid connected VSI with an LCL Filter,” IEEE Trans. on Power Electron., vol. 28, no. 5, pp. 2259-2268, May. 2013.
  • N. Trinh, and H. H. Lee, ―An advanced current control strategy for three phase shunt active power filters,‖ IEEE Trans. on Ind. Electron., vol. 60, no. 12, pp. 5400-5410, Dec. 2013.
  • F. Petit, G. Robles, and H. Amaris, ―Current reference control for shunt active power filters under non sinusoidal voltage conditions, IEEE Trans. on Power Del., vol. 22, no.4, pp. 2254–2261, Oct. 2007.

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