Real-time control of shunt active power filter under distorted grid voltage and unbalanced load condition using self-tuning filter

ABSTRACT:

In this paper, an alternative control method is proposed to improve the harmonic suppression efficiency of the activepower filter in a distorted and an unbalanced power system to compensate for the perturbations caused by the unbalanced nonlinear loads. The proposed method uses a self-tuning filter (STF) to process the grid voltage in order to provide a uniform reference voltage to obtain the correct angular position of the phase locked loop. Moreover, the required compensation currents are obtained by implementing another STF in the transformed set of currents in order to separate the fundamental and the harmonic currents. This allows the calculation of a precise reference current for the unbalanced, the non-linear and the variable load conditions. The proposed control method gives an adequate compensating current reference even for a nonidealvoltage and unbalanced current conditions. The real-time control of the filter under the distorted and the unbalanced power system is developed in an RT-LAB real-time platform. The results obtained in the software-in-the-loop configuration are presented to verify the effectiveness of the proposed control technique.

 

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1 Block diagram of the APF and the proposed control method

 EXPECTED SIMULATION RESULTS:

Fig. 2 Voltage and the current waveforms

a Ideal grid voltage

b Non-ideal (distorted and unbalanced) grid voltage

c Load currents under the ideal grid voltage

d Load currents under the non-ideal grid voltage

Fig. 3 Compensation of the grid current harmonics by using the conventional dq method

a Under the ideal voltage

b Under the non-ideal voltage, and by using the conventional pq method

c Under the ideal voltage

d Under the non-ideal voltage

Fig. 4 Compensation of the grid current harmonics

a By using the STF-based pq theory under the ideal voltage

b By using the STF-based pq theory under the ideal voltage

c By using the proposed method under the ideal voltage

d By using the proposed method under the non-ideal voltage

CONCLUSION:

In this paper, the design of a control method that generates thecorrect reference current signal in order to satisfy the requirements of a harmonic suppression and a reactive power compensation, for the unbalanced non-linear load combinations under the case of the non-ideal grid voltageconditions have been discussed. An alternate method is proposed where two STF are applied to manage the distorted and the unbalanced voltage and current. In the proposed method, the distorted and the unbalanced voltages are first processed by using the STF to determine the correct angular positions. Then, a second STF is used toextract the balanced load current waveforms. This methodeliminates the need for additional low-pass or high-pass filtering when extracting the harmonic components from the fundamental. A step-by-step performance study, in a real-time environment, shows that the proposed control technique is able to generate the proper compensating reference current during the steady state and the dynamic load change conditions under the distorted and the unbalanced grid voltage conditions.

REFERENCES:

1 Sasaki, H., Machida, T.: ‘A new method to eliminate AC harmoniccurrents by magnetic flux compensation-considerations on basic design’, IEEE Trans. Power Appar. Syst., 1971, PAS-90, (5), pp. 2009–2019

2 Gyugyi, L., Strycula, E.C.: ‘Active AC power filters’. Proc. IEEE Ind. Appl. Ann. Meeting, 1976, vol. 19-C, pp. 529–535

3 Singh, B., Al-Haddad, K., Chandra, A.: ‘A review of active filters for power quality improvement’, IEEE Trans. Ind. Electron., 1999, 46, (5), pp. 960–971

4 Mariun, N., Alam, A., Mahmod, S., Hizam, H.: ‘Review of control strategies for power quality conditioners’. National Power and Energy Conf. Proc., PECon 2004, 29–30 November 2004, pp. 109–115

5 Akagi, H., Kanazawa, Y., Nabae, A.: ‘Instantaneous reactive power compensators comprising switching devices without energy storage components’, IEEE Trans. Ind. Appl., 1984, IA-20, (3), pp. 625–630

Using "STF-PQ” Algorithm and Hysteresis Current Control in Hybrid Active Power Filter to Eliminate Source Current Harmonic

ABSTRACT:

According to importance of power quality in power network, improvement of compensator equipment and ways of efficiency increasing can reduces destroyer effect on network. Active power filters as more importance and finance in network and industrial has depended detector algorithm and switching technique. This paper presents a novel algorithm (STF-PQ). This algorithm base on harmonic extract is divided into two parts as feedback loop and feed forward loop. Then, the hysteresis current control has been used to produce the switching pattern. A comparison between PWM and hysteresis current control has been performed that shows the efficiency and simplicity of hysteresis current control. Simulation of this filter has been done in Matlab/Simulink to prove the good performance of STF-PQ and hysteresis current control in hybrid filters.

KEYWORDS:

1.      Hybrid active power filters

2.      Self tuning filter

3.      Hystrsis current control

4.      Matlab/Simulink

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig.1 Parallel hybrid active filter configuration

 EXPECTED SIMULATION RESULTS:

Fig.2 simulation Results

CONCLUSION:

According to development of power systems in industrial such as UPS, speed control of electrical machine, electrical furnace, computers and non-linear load that cause increasing of harmonic in network, Undesirable effect of harmonic is one of power transfer problem. This is why of standard codifying on THD limitation. Thus, it is necessary to detect and remove it until under permit limit. In this paper a novel algorithm of "STF-PQ" has been proposed to detect harmonics in power system. Then hysteresis current control has been used to make the reference current due to its simplicity and high accuracy. The comparison between PWM and hysteresis proves that use of PWM has more complexity and calculation to generate pulses. Simulation results show the efficiency of this power filter in harmonic elimination.

REFERENCES:

[1] J. C. Das,” Passive filters- Potentialities and limitations” IEEETransactions on industry applications, vol. 40, pp. 345-362, (2004).

[2] Park, J-h. Sung and K. Nam," A New parallel hybrid filter configuration minimizing active filter size" IEEE/PESC Ann. Meeting Conf, vol. 1, pp.400-405 (1999)

[3] B. N. Singh, Bhim Singh, A. Chandra and K. Al-Haddad," Digital implementation of new type of hybrid filter with simplified control strategy" Conference Proceeding IEEE-APEC 99., vol 1, pp. 642- 648 (1999)

[4] H. Fujita, and H. Akagi," A practical approach to harmonic compensatreion in power systems-Series connection of passive and shunt active filters," IEEE Trans. Ind. Appl, vol 27, pp. 1020-1025 (1991)

[5] Michael John Newman, Daniel Nahum Zmood , Donald Grahame Holmes," Stationary Frame Harmonic Reference Generation for Active Filter Systems", IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 38, NO. 6, NOVEMBER/DECEMBER 2002

Fuzzy logic controller for five-level shunt active power filter under distorted voltage conditions

 ABSTRACT:

In this paper, a five-level inverter is used as a shunt active power filter (APF), taking advantages of the multilevel inverter such as low harmonic distortion and reduced switching losses. It is used to compensate reactive power and eliminate harmonics drawn from a diode rectifier feeding a RL load under distorted voltage conditions. The active power filter control strategy is based on the use of self tuning filters (STF) for reference current generation and a fuzzy logic current controller. The use of STF instead of classical extraction filters allows extracting directly the voltage and current fundamental components in the a-J3 axis without phase locked loop (PLL). This study is divided in two parts. The first one deals with the harmonic isolator which generates the harmonic reference currents. The second part focuses on the generation of the switching pattern of the inverter by using a fuzzy logic controller applied and extended to a five level shunt APF. The MA TLAB Fuzzy Logic Toolbox is used for implementing the fuzzy logic control algorithm. The obtained results show that, the proposed shunt active power filter controller has produced a sinusoidal supply current with low harmonic distortion and in phase with the line voltage.

KEYWORDS:

1.      Active filter

2.      Harmonics isolator

3.      Distorted voltage conditions

4.      Self-tuning filter

5.      Fuzzy logic control and PWM control

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig1.power system configuration

EXPECTED SIMULATION RESULTS:

Fig. 2. Supply voltage Vs waveform

Fig. 3. Supply current Is waveform without filtering.

Fig. 4. Supply current Is waveform with filter.

Fig. 5. Active filter current If

Figure 6. APF output voltage Vab (line to line) for a five-level with

PDPWM

Fig. 7. DC voltage of the condensers Vdc

CONCLUSION:

This paper has discussed the control and performance improvement of a shunt active power filter under distorted voltage conditions, using a fuzzy logic controller for a five level shunt active power filter based on the optimization of the reference current generation and using a modified version of the p-q theory and PDPWM to generate switching signals. Simulation results have shown high performances in reducing harmonics and power factor correction. The use of the Self-tuning filter leads to satisfactory improvements since it perfectly extracts the harmonic currents under distorted conditions. With the fuzzy logic control, the active filter can be adapted easily to more severe constraints, such as unbalanced conditions. In addition, results have demonstrated the major advantages of using STF and fuzzy logic controller in filter control. The Five-level APF provides numerous advantages such as improvement of supply current waveform, less harmonic distortion and possibilities to use it in high power applications. As final conclusion, the obtained results showed that, the proposed active power filter controller have provided a sinusoidal supply current with low harmonic distortion and in phase with the line voltage.

REFERENCES:

[I] H. Akagi, "Trend in active power line conditioners," IEEE Trans Power Electronics, vol.9, pp.263-268, August 1994.

[2] H.-K. Chiang, B.-R. Lin, K.-T. Yang, and K.-W.Wu, "Hybrid active power filter for power quality compensation," IEEE Power Electronics and Drives Systems,voL2, pp.949-954, 2005.

[3] X. Wanfang, L. An, and W. Lina, "Development of hybrid active power filter using intelligent controller, " Autom. Electric Power Syst. Vo1.27, pp.49-52,2003.

[4] O. Vodyakho, T. Kim, S. Kwak, 'Three-level inverter based active power filter for the three-phase, four-wire system," IEEE Power Electronics Specialists Conference, pp. 1874-1880,2008.

[5] G.W. Chang, C.M. Yeh, "Optimization-based strategy for shunt active power filter control under non-ideal supply voltages, " lEE Electric Power Applications, voL152, pp.182-190, March 2005.

Comparison of two compensation control strategies for shunt Active Power Filter

ABSTRACT:

The purpose of this paper is to present a harmonic mitigation using a shunt active filter with accurate harmonic current identification and compensation based on instantaneous active and reactive power theory and a self-tuning filter for the harmonic isolation and a fuzzy hysteresis band technique for the current control. In order to find the best strategy for the power quality improvement, a comparative study has been illustrated. The Analysis and simulation results using Matlab/Simulink confirm the effectiveness and limits of the proposed methods and also show the performances of fuzzy logic control which provides flexibility, high precision and fast response.

KEYWORDS:

1.      Active power filter (APF)

2.      Fuzzy logic control

3.      THD

4.      Harmonic

5.      Hysteresis-band control

6.      Power quality

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Figure 1. Active Power Filter

 EXPECTED SIMULATION RESULTS:

Figure 2. Harmonic compensation with p-q theory and fuzzy hysteresis band control

Fig 3.Source current's harmonic spectrum (p-q theory)

Figure 4. Harmonic compensation with STF theory and fuzzy hysteresis band control

Figure 5. Source current's harmonic spectrum (STF)

Figure 6. The DC voltage

CONCLUSION:                                                    

In this paper the quality of the energy is improved by using the active filtering. A model of shunt active power filter is illustrate with its control strategy based on the p-q theory concept and a STF using fuzzy logic current control, the developed techniques shown excellent performances in harmonics mitigation and reactive power compensation. The comparative evaluation proved that the STF gives better quality filtering then the conventional p-q theory which is the main objective to be achieved. To confirm the efficiency of this solution and to improve the system response experimental application and others techniques as Neuro-fuzzy control can be developed.

REFERENCES:

[1] H. USMAN, H. HIZAM, M. AMRAN, M. RADZI "Simulation of single-phase shunt active power filter with fuzzy logic control ler for power quality improvement", clean energy and technology, 2013.

[2] A CHAOUI, J-P. GAUBERT, A BOUAFIA, "Experimental validation of new direct power control switching table for shunt active power filter power", conference on Electronics and Applications (EPE), 2013.

[3] R. BELAIDI, M.HATTI, A HADDOUCHE, M. M. LARAFI, "Shunt active power filter connected to a photovoltaic array for compensating harmonics and reactive power simultaneously", 4th international conference on power engineering, energy and electrical drives, may 2013.

[4] B. SINGH, K. AL-HADDAD, A CHANDRA, "A review of active filters for power quality improvement", IEEE transactions on industrial electronics, vol. 46, no. 5, October 1999.

[5] G. W. CHANG, C. M. YEH, "Optimisation-based strategy for shunt active power filter control under non-ideal supply voltages ",lEE proceedings - electric power applications, vol. 152, no. 2, pp. 182,2005.

Hardware Implementation of a Three-Phase Active Filter System with Harmonic Isolation Based on Self-Tuning-Filter

ABSTRACT:

This paper presents the hardware implementation of a new control method based on an improved harmonic isolation for active filter systems. The harmonic generation is based on Self Tuning Filters for the harmonic isolation and on a modulated hysteresis current controller for the current control technique. This active filter is intended for harmonic compensation of a diode rectifier feeding a RL load. The study of the active filter control is divided in two parts. The first part deals with the harmonic isolator which generates the harmonic reference currents and is implemented into a Dspace DS1104 prototyping card. The second part focuses on the generation of the switching pattern of the IGBTs of the inverter by the modulated hysteresis current controller, implemented into an analogue card. The use of Self Tuning Filters instead of classical extraction filters allows extracting directly the voltage and current fundamental components in the α-β axis at high performances, without any Phase Locked Loop. The effectiveness of the new proposed method is verified by computer simulation and validated by experimental study.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig 1. Power system configuration.

EXPECTED SIMULATION RESULTS:

Fig 2. Simulation results for the phase 1 under sinusoidal voltage conditions: (a) load current, (b) supply current after compensation

CONCLUSION:

This paper has discussed the control and performances of a shunt active power filter. The hardware implementation has been performed based on the optimisation of the reference current generation and using a modified version of the p-q theory. The control of the active filter was divided in two parts, the first one realized by the DSPACE system to generate the reference currents and the second one achieved by an analogue card for the switching pattern generation, implementing a modulated hysteresis current controller.

STFs have been introduced in the proposed modified version of the p-q theory instead of classical extraction filters (high pass and/or low pass filters) for both grid voltages and load currents. The use of this filter experimentally leads to satisfactory performances since it extracts the harmonic currents at high performances. For the current controller, we implemented the modulated hysteresis current controller to obtain a fixed switching frequency for the IGBT’s.

The simulation and the experimental results have demonstrated and conforted the effectiveness of using STF and modulated hysteresis current controller in the filter control. In conclusion, the proposed control for shunt active power filter is effective in installation on an actual power system.  

REFERENCES:

[1] J. C. Das,” Passive filters- Potentialities and limitations” IEEETransactions on industry applications, vol. 40, pp. 345-362 (2004).

[2] H. Akagi, “Active and hybrid filters for power conditioning” IEEE International Symposium on Indsutrial Electronics, vol 1, (2000).

[3] P. Jintakosonwit, H. Fujita and H. Akagi,” Control and performance of a fully-digital-controlled shunt active filter for installation on a power distribution system” IEEE-Transactions on power electronics, vol. 17, pp. 323-334 (2002).

[4] M. P. Kazmierkowski and L. Malesani, “Current control techniques for three-phase voltage source PWM converters: a survey” IEEE Trans. Ind. Elect. vol.45, n°5, pp. 691-703 (1998).

[5] H. Akagi, Y. Kanazawa and A. Nabae “Generalized theory of the instantaneous reactive power in three-phase circuits” , Proceeding International power electronics conference. Tokyo, Japan, PP. 1375-1386, (1983).