Development of Control Techniques Using Modified Fuzzy Based SAPF for Power Quality Enhancement

ABSTRACT:

Low power distribution systems have severe power quality issues due to the non-linearity of several residential and industrial loads. The main power quality issue is the harmonics leading to the overheating of the transformers in the distribution systems. By employing passive filters, active filters, and custom power devices, the harmonics in the source current can be reduced. To overcome the drawbacks of conventional tuned filters and active power filters the modified shunt active power filter was introduced with the fuzzy logic controller. In this paper, an effective way of reducing the total harmonic distortion using three-phase three-wire shunt active filter is carried out and this has been investigated through three control methods namely synchronous reference frame theory, real and reactive power theory, and indirect reference current theory. The recognized control methods are implemented with the fuzzy controller to improve the performance of the induction motor drive. The hardware setupwas implemented for the proposed fuzzy-based control technique to achieve better performance in terms of reduced total harmonic distortion and DC link voltage and improved speed performance of induction motor drive when compared to other control methods. Further power factor correction and better reactive power compensation are achieved by implementing hardware.

KEYWORDS:

1.      Power quality

2.      SPAF

3.      FUZZY controller

4.      Total harmonics distortion

5.      DC link voltage

6.      Induction motor drives

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Figure 1. Schematic Representation Of The Srf Control Technique For Shunt Apf.

 EXPECTED SIMULATION RESULTS:

 

Figure 2. Voltage And Current Waveforms Of Sapf Using Srf Method (A) Source Voltage (B) Load Current (C) Voltage At Pcc (D) Source Current (E) Filter Current (F) Dc Link Voltage.

Figure 3. A To C Active And Reactive Power Of Sapf: A) By Irct Method B) By P-Q Method C) By Srf Method.

 

Figure 4. A To C Power Factor Of Sapf: A) By Irct Method B) By P-Q Method C) By Srf Method.

 

Figure 5. Capacitor Dc-Link Voltage Of Three Control Strategies.

 

Figure 6. Voltage And Current Waveforms Of Sapf With An Induction Motor Drive Load (A) Input Voltage (B) Load Current (C) Voltage At Pcc (D) Input Current (E) Filter Current (F) Dc Link Voltage.

 

Figure 7. Rotor Current, Speed In Rad./Sec. And Torque Of Induction Motor Drive.

 CONCLUSION:

The simulating of the non-linear system of bridge rectifier with and without SAPF has been analyzed.The % THD has been decreased from 63.8 % to 0.48 % in the SRF method,2.04 % in the p-q method,6.67 % in the IRCT method,1.30 % for the induction motor drive load,1.07 % for the different load is considered. The hardware setup as implemented for the proposed work and the Power factor is improved by the percentage of 6.38 %, Reactive power compensation is achieved up to 88.3 % and Source current harmonics is reduced from 23.9 % to 3.2 %.The system has been analyzed with two types of load. For the bridge rectifier load, the total harmonic distortion was reduced to 0.48 %. In the induction motor drive load the % THD is reduced to 1.30%,It shows that the active filter is providing reduced % THD for the different types of load and the robust speed performance has been achieved using fuzzy-based SAPF techniques.

REFERENCES:

[1] K. Al-Zamil and D. A. Torrey, ``Harmonic compensation for three-phase adjustable speed drives using active power line conditioner,'' in Proc. Power Eng. Soc. Summer Meeting, Jul. 2000, pp. 16_20.

[2] H. Akagi, ``Active harmonic filters,'' Proc. IEEE, vol. 93, no. 12, pp. 2128_2141, Dec. 2005.

[3] H. Fujita, T. Yamasaki, and H. Akagi, ``A hybrid active filter for damping of harmonic resonance in industrial power systems,'' IEEE Trans. Power Electron., vol. 15, no. 2, pp. 215_222, Mar. 2000.

[4] V. Khadkikar, ``Enhancing electric power quality using UPQC: A comprehensive overview,'' IEEE Trans. Power Electron., vol. 27, no. 5, pp. 2284_2297, May 2012.

[5] L. F. C. Monteiro, J. G. Pinto, J. L. Afonso, and M. D. Bellar, ``A three-phase four-wire unified power quality conditioner without series transformers,'' in Proc. 38th Annu. Conf. IEEE Ind. Electron. Soc., Montreal, QC, Canada, Oct. 2012, pp. 25_28.

DC-Link Voltage Research of Photovoltaic Grid-Connected Inverter Using Improved Active Disturbance Rejection Control

ABSTRACT:

In this paper, a robust DC-link voltage control scheme is proposed to improve the tolerance of photovoltaic (PV) grid-connected inverter to disturbances. The sensitive characteristic of the DC-link voltage complicates the dynamics of the inverter control system and limits its overall performance, especially when uncertain disturbances are considered. To cope with this issue, a voltage controller based on the linear active disturbance rejection control (LADRC) is designed. By exploring the principle of deviation regulation, an improved linear extended state observer (LESO) is established to ensure that the total disturbance can be estimated in a relatively timely manner. The linear state error feedback (LSEF) control law is generated to compensate for the total disturbance, which reduces the plant to approximate the canonical cascaded double integrator. The stability and disturbance rejection capability of the improved LADRC are further analyzed in frequency domain. Finally, theoretical analysis and experimental results con_rm the feasibility of the proposed control scheme.

KEYWORDS:

1.      Photovoltaic (PV) grid-connected inverter

2.      DC-link voltage

3.      Linear active disturbance rejection control (LADRC)

4.      Deviation regulation

5.      Total disturbance

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

 

Figure 1. Schematic Of Two-Stage Pv Grid-Connected System Structure.

 EXPECTED SIMULATION RESULTS:

Figure 2. Bode Plots For Estimating The Total Disturbance.

Figure 3. Time-Domain Curve For Estimating Internal Disturbance.

Figure 4. Bode Plots For Comparing Disturbance Term.

 

Figure 5. Bode Plots Of Disturbance Term With Different Bandwidths. (A) !C D 30(Rad=S) (B) !O D 30(Rad=S).

CONCLUSION:

 In the PV grid-connected system, the robust control of DC-link voltage is crucial for energy transmission, which directly affects the power quality. Therefore, a DC-link voltage control strategy based on improved LADRC was proposed for grid-connected inverter in this paper. By describing the stability problem and power relationship of the DC-link, the voltage outer loop is modeled. Both theoretical analysis and experimental results prove that the proposed voltage control scheme achieves better control performance, either during the start-up process or operating conditions variation. The reason is that the D-LESO established according to the principle of deviation regulation can estimate the total disturbance in a relatively timely and accurate manner, which lays a foundation for disturbance compensation. At present, an increasing number of scholars are focusing their research on the combination of LADRC and intelligent algorithms, such as neural networks and fuzzy control. This paper is expected to provide these scholars with more ideas in order to apply LADRC more widely in the industrial field.

 REFERENCES:

[1] A. Demirbas, ``Global renewable energy projections,'' Energy Sources, B, Econ., Planning, Policy, vol. 4, no. 2, pp. 212_224, Oct. 2009.

[2] B. Yang, W. Li, Y. Zhao, and X. He, ``Design and analysis of a grid connected photovoltaic power system,'' IEEE Trans. Power Electron., vol. 25, no. 4, pp. 992_1000, Apr. 2010.

[3] E. Romero-Cadaval, B. Francois, M. Malinowski, and Q.-C. Zhong, ``Gridconnected photovoltaic plants: An alternative energy source, replacing conventional sources,'' IEEE Ind. Electron. Mag., vol. 9, no. 1, pp. 18_32, Mar. 2015.

[4] L. Hassaine, E. OLias, J. Quintero, and V. Salas, ``Overview of power inverter topologies and control structures for grid connected photovoltaic systems,'' Renew. Sustain. Energy Rev., vol. 30, pp. 796_807, Feb. 2014.

[5] B. Guo, S. Bacha, M. Alamir, and H. Iman-Eini, ``A robust LESO-based DC-link voltage controller for variable speed hydro-electric plants,'' in Proc. IEEE Int. Conf. Ind. Technol. (ICIT), Feb. 2019, pp. 361_366.

 

 

Control Strategy Research of D-STATCOM Using Active Disturbance Rejection Control Based on Total Disturbance Error Compensation

ABSTRACT:

The distribution static synchronous compensator (D-STATCOM) has the characteristics of nonlinearity, multivariable and strong coupling. Based on the analysis of the D-STATCOM mathematical model, in order to improve the performance of the linear active disturbance rejection controller (LADRC), solve the coupling problem between the d-axis and q-axis current and improve the dynamic tracking response speed and anti-interference ability. A controller with LADRC that compensates the error of the total disturbance is proposed, and the stability of the improved first-order LADRC is proved by the Lyapunov stability theory. Then the output of the full interference channel is corrected to improve the anti-interference ability of the system and the interference observation ability of the linear extended state observer (LESO) to high frequency noise. Through the analysis of the Bode diagram in the frequency domain, compared with the traditional LADRC, the improved LADRC proposed in this paper has better anti-interference performance. Finally, the improved first-order LADRC is used to replace the traditional D-STATCOM control strategy for current inner loop control, which effectively reduces the disturbance observation error of LESO. The experimental results show that the improved LADRC control performance is better than the proportional integral (PI) controller, and it has better tracking performance and anti-interference performance.

KEYWORDS:

1.      Distribution static synchronous compensator (D-STATCOM)

2.      Total disturbance

3.       Linear active disturbance rejection control (LADRC)

4.      Linear extended state observer (LESO)

5.      Anti-interference performance.

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

 

Figure 1. Overall Control Structure Of Voltage Type D-Statcom Device.

 EXPECTED SIMULATION RESULTS:

Figure 2. Comparison Of Reactive Current Tracking Curves Under The Control Of Pi And Improved Ladrc Under Low Voltage Ride-Through.

Figure 3.Comparison Of Reactive Current Tracking Under Pi And Improved Ladrc Control With Increasing And Decreasing Load.

Figure 4. Comparison Of Reactive Power And Active Power Under The Control Of Pi And Improved Ladrc Under Low Voltage Ride-Through.

Figure  5. Comparison Of Reactive Power And Active Power Under Pi And Improved Ladrc Control With Increasing And Decreasing Load.

 

CONCLUSION:

 Aiming at the nonlinear, multivariable and strong coupling characteristics of D-STATCOM, this paper proposes an improved first-order LADRC for the internal current loop of the D-STATCOM system. The key to LADRC performance is whether the extended state observer can accurately estimate the state variables of the system. The innovation of this paper is to propose a linear active disturbance rejection controller that compensates the total disturbance error to improve the control performance of the entire control system. And through the rigorous mathematical derivation of the Lyapunov stability theory, the stability of the improved first-order LADRC is proved, and the asymptotic stability conditions are given. Then correct the output of the total disturbance channel. Finally, the experiment proved the correctness and feasibility of the improved first-order LADRC. In addition, this article only considers the situation of balanced load and symmetrical grid voltage failure. Future work will focus on the study of the D-STATCOM control method of the LADRC under unbalanced load and distorted grid voltage.

 REFERENCES:

 [1] H. Bakir and A. A. Kulaksiz, ``Modelling and voltage control of the solarwind hybrid micro-grid with optimized STATCOM using GA and BFA,'' Eng. Sci. Technol., Int. J., vol. 23, no. 3, pp. 576_584, Jun. 2020.

[2] S. R. Marjani, V. Talavat, and S. Galvani, ``Optimal allocation of DSTATCOM and recon_guration in radial distribution network using MOPSOalgorithm in TOPSIS framework,'' Int. Trans. Electr. Energy Syst., vol. 29, no. 2, p. e2723, 2019.

[3] S. Rezaeian-Marjani, S. Galvani, V. Talavat, and M. Farhadi-Kangarlu, ``Optimal allocation of D-STATCOM in distribution networks including correlated renewable energy sources,'' Int. J. Electr. Power Energy Syst., vol. 122, Nov. 2020, Art. no. 106178.

[4] R. O. de Sousa, A. F. Cupertino, L. M. F. Morais, and H. A. Pereira, ``Minimum voltage control for reliability improvement in modular multilevel cascade converters-based STATCOM,'' Microelectron. Rel., vol. 110, Jul. 2020, Art. no. 113693.

[5] W. Xiao, J. Li, and Y. Wang, ``Study on reactive power compensation strategy based on STATCOM,'' Power Capacitor Reactive Power Com- pensation, vol. 40, no. 6, pp. 24_29, 2019.

Control of switched reluctance generator in wind power system application for variable speeds

ABSTRACT:

Switched reluctance generators (SRGs) come into prominence in other electrical machines with its simple structure, only stator winding, reliability, high fault tolerance and the possibility of working within wide speed range. These generators are used especially in wind power plants due to their ability to operate in variable speed range and applications of aviation and electric cars. In this study, the control of the SRG was performed. A simulation of SRG driver in Matlab/Simulink was performed and the real-time implementation control of SRG is carried out on DS1103 Ace kit digital signal processor to determine the performance of the SRG. The output voltage of the SRG is controlled by the proportional-integral (PI) voltage controller. As a result, the graphs of change in SRG phases currents and SRG output voltage were obtained according to different parameters. Simulation results compared with experimental results. Consequently, they overlap on experimental results.

KEYWORDS:

1.      Switched reluctance generator

2.      Wind power system

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. (a) Block diagram of SRG based WECS, (b) Mechanical power curves of the

wind turbine system.

EXPECTED SIMULATION RESULTS:

Fig. 2. The graph of the SRG’s phase currents obtained by (a) simulation, (b)

experimental (n = 1000 rpm, V = 30 V, hon = 15_, hoff = 30_).

Fig. 3. The graph of SRG’s phase currents obtained by (a) simulation, (b)

experimental (n = 1500 rpm, V = 15 V, hon = 15_, hoff = 30_).

Fig. 4. The graph of SRG’s phase currents obtained with by (a) simulation, (b)

experimental (n = 1500 rpm, V = 25 V, hon = 15_, hoff = 30_).

Fig. 5. The graph of the SRG’s phase currents obtained by (a) simulation, (b)

experimental (n = 1500 rpm, V = 30 V, hon = 15_, hoff = 30_).

Fig. 6. The graph of the SRG’s output voltage obtained by (a) simulation (b)

experimental (V = 15 V).

 

Fig. 7. The graph of the SRG’s output voltage obtained by (a) simulation (b)

experimental (V = 25 V).

 

Fig. 8. The graphs of the SRG’s output voltage obtained by (a) simulation (b)

experimental (V = 30 V).

Fig. 9. The graph of the current of phase A according to different (a) turn-off angles (hon = 15_), (b) turn-on angles (hoff = 30_).

CONCLUSION:

The output voltage of the SRG is controlled by using PI voltage controller and simulated by using Matlab/Simulink software in this study. DS 1103 Ace kit controller was used to obtain experimental results. It was proven that the simulation results are accurate when compared with the experimental results. In addition, the effect of the firing angles on phase currents of the SRG was investigated The results obtained in this study shows that changes in phase currents were affected by selecting the turn-on and the turn-off angle.

 REFERENCES:

[1] Global Wind Energy Council, Global wind report 2019, March (2020). http:// www.gwec.net/

[2] Hasanien HM, Muyeen SM. Speed control of grid-connected switched reluctance generator driven by variable speed wind turbine using adaptive neural network controller. Electric Power Syst. Res. 2012;84(1):206–13.

[3] Neto PJS, Barros TAS, Paula MV, Souza RR, Filho ER. Design of computational experiment for performance optimization of a switched reluctance generator in wind systems. IEEE Trans. Energy Convers. 2018;33(1):406–19.

[4] Omaç Z, Kürüm H, Selçuk AH. Design, analysis and control of a switched reluctance motor having 18/12 poles. Fırat U. J. Sci. Eng. 2007;19:339–46.

[5] Omaç Z, Kürüm H, Selçuk AH. Digital current control of a switched reluctance motor. Int. J. Electr. and Power Eng. 2011;5:54–61.

Control of Photovoltaic Inverters for Transient and Voltage Stability Enhancement

 ABSTRACT:

The increasing number of megawatt-scale photovoltaic (PV) power plants and other large inverter-based power stations that are being added to the power system are leading to changes in the way the power grid is operated. In response to these changes, new grid code requirements establish that inverter based power stations should not only remain connected to the grid during faulty conditions but, also provide dynamic support. This feature is referred in the literature to as momentary cessation operation. The few published studies about momentary cessation operation for PV power plants have not shed much light on the impact of these systems on the overall power system stability problem. As an attempt to address this issue, this paper proposes a control scheme for PV inverters that improves the transient stability of a synchronous generator connected to the grid. It is shown through the paper that the proposed control scheme makes the PV inverter's dc link capacitors absorb some of the kinetic energy stored in the synchronous machine during momentary cessation. Besides that, the proposed solution is also able to improve voltage stability through the injection of reactive power. Experimental and simulation results are presented in order to demonstrate the effectiveness of the proposed control scheme.

KEYWORDS:

1.      Photovoltaic generation

2.      Synchronous machine

3.      Transient stability

4.      Voltage stability

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

  

Figure 1. Three-Phase Diagram Of A Utility-Scale Hybrid Power System.

 EXPECTED SIMULATION RESULTS:

Figure 2. Experimental Results Showing The Performance Of The Proposed Control. Results Obtained For: (A) No Control Scheme Implemented; (B) Inverter With The Proposed Control Scheme And No Reactive Power Support; And (C) Inverter With The Proposed Control Scheme And Reactive Power Support.

 

Figure 3. Comparative Responses Of The Hybrid System Subjected To A 2lg Fault. (A) Sm Active Power Output. (B) Pv System Active Power Output. (C) Sm Reactive Power Output. (D) Pv System Reactive Power Output.

 

Figure 4. Comparative Responses Of The Hybrid System Subjected To A 2lg Fault. (A) Pcc Voltage. (B) Dc Link Voltage. (C) Pv Unit's Inverter Current Output. (D) Sm Rotor Angle.

 

CONCLUSION:

In this work, a control scheme for PV inverters is proposed to act during faults that could compromise the transient and voltage stability of a hybrid power system. The analysis demonstrated that the proposed control scheme can act while the PV system is in MC operation, supporting the grid to recover stability during and after a disturbance on the transmission grid. The proposed control scheme makes the SM kinetic energy to be absorbed into the dc link capacitors to ensure transient stability. Besides that, it also enables the injection of reactive power into the grid to support voltage stability. Experimental and simulation results have shown that the proposed control scheme can reduce the rotor angle oscillations within the first few cycles of the fault, effectively ensuring the SM's transient stability. It has also shown improvements in the grid voltages during the fault period and a very fast post-fault voltage recovery in comparison with other FRT control schemes.

REFERENCES:

[1] M. Milligan, B. Frew, B. Kirby, M. Schuerger, K. Clark, D. Lew, P. Denholm, B. Zavadil, M. O'Malley, and B. Tsuchida, ``Alternatives no more: Wind and solar power are mainstays of a clean, reliable, affordable grid,'' IEEE Power Energy Mag., vol. 13, no. 6, pp. 78_87, Nov. 2015.

[2] N. W. Miller, ``Keeping it together: Transient stability in a world of wind and solar generation,'' IEEE Power Energy Mag., vol. 13, no. 6, pp. 31_39, Nov. 2015.

[3] IEEE Standard for Interconnecting Distributed Resources With Electric Power Systems, IEEE Standard 1547-2003, Jul. 2003.

[4] W. Weisheng, C. Yongning, W. Zhen, L. Yan, W. Ruiming, N. Miller, and S. Baozhuang, ``On the road to wind power: China's experience at managing disturbances with high penetrations of wind generation,'' IEEE Power Energy Mag., vol. 14, no. 6, pp. 24_34, Nov. 2016.

[5] IEEE Standard for Interconnection and Interoperability of Distributed Energy Resources With Associated Electric Power Systems Interfaces, IEEE Standard 1547-2018, Apr. 2018.