Power Quality Enhancement in Sensitive Local Distribution Grid Using Interval Type-II Fuzzy Logic Controlled DSTATCOM

ABSTRACT:

In the current scenario, integration of renewables, growth of non-linear industrial and commercial loads results in various power quality issues. Among commercial utilities connected to the grid, hospital-operated loads include sensitive, linear, non-linear, and unbalanced loads. These loads are diverse as well as prioritized, which also causes major power quality issues in the local distribution system. Due to its widespread divergence, it leads to harmonic injection and reactive power imbalance. Distribution Static Compensator (DSTATCOM) is proposed as a solution for harmonic mitigation, load balancing, reactive power imbalances, and neutral current compensation. The present work utilizes Interval Type-2 Fuzzy Logic Controller (IT2FLC) with Recursive Least Square (RLS) filter for generating switching pulses for IGBT switches in the DSTATCOM to improve power quality in the Local Distribution Grid. The proposed approach also shows superior performance over Type 1 fuzzy logic controller and Conventional PI controller in mitigating harmonics. For effective realization, the proposed system is simulated using MATLAB software.

KEYWORDS:

1.      Local distribution grid

2.      DSTATCOM

3.      Interval type 2 fuzzy logic controller

4.      Power quality and recursive least square filter

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Figure 1. Proposed Dstatcom Configuration With Interval Type-2 Fuzzy Logic Controller.

 

EXPECTED SIMULATION RESULTS:

Figure 2. Source And Load Current Waveforms Of The Hospital Loads Connected To Ldg Without Dstatcom.

Figure 3. Phase B Harmonic Spectrum.

Figure 4. Source Current Waveforms Of The Hospital Loads Connected To Ldg With Dstatcom.

Figure 5. Load Current Waveforms Of The Hospital Loads Connected To Ldg With Dstatcom.

CONCLUSION:

The performance of IT2FLC based DSTATCOM has been validated in this work and satisfactory results corroborate its effectiveness when sensitive loads are connected to the grid. With proficient behavior of control along with its fast response, it has been proved effective in mitigating harmonics. The simulated results and tabulation highlight the efficacy of the proposed controller over conventional ones. This paper paid close attention to the effective operation of the local distribution grid with sensitive loads which are the source of disturbances from the generation viewpoint. Integration of IT2FLC based DSTATCOM in the system significantly reduces the total harmonic distortion in the system and the RLS filter helps in _ne-tuning it to the acute levels. Also, substantial improvement in the total harmonic distortion is aided by reducing the harmonic value of currents at the source side and provides a much better profile of voltage and current waveforms. Neutral current flow due to unbalanced loads is mitigated with the help of the fourth leg of VSC. Summarized results show that THD levels are less when compared with PI controller and T1FLC at various time instant.

REFERENCES:

[1] A. Ghosh and G. Ledwich, Power Quality Enhancement Using Custom Power Devices. Norwell, MA, USA: Kluwer, 2002.

[2] B. Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques. London, U.K.: Wiley, 2015.

[3] R. Bert, ``Power quality issues and the effects on medical equipment,'' J. Clin. Eng., vol. 22, no. 1, pp. 35_40, Jan. 1997.

[4] U. Rao, S. N. Singh, and C. K. Thakur, ``Power quality issues with medical electronics equipment in hospitals,'' in Proc. Int. Conf. Ind. Electron., Control Robot., 2010, pp. 18_34.

[5] L.-G. Angantyr, E. Häggeström, and P. Kulling, ``KAMEDO report no. 93_The power failure at Karolinska university hospital, Huddinge, 07 April 2007,'' Prehospital Disaster Med., vol. 24, no. 5, p. 468, 2009.

Power and Current Limiting Control of Wind Turbines Based on PMSG Under Unbalanced Grid Voltage

 ABSTRACT:

Unbalanced grid voltage sags are the severe challenge for wind power generation system which connected to the grid successfully. The dc bus voltage and output power will fluctuate under unbalanced grid voltage. Moreover, the voltage sags will lead to the increase of peak current, which will bring potential safety hazards to the operation of wind power system. This paper proposes a simple current limiting control scheme without auxiliary equipment, which based on the detailed analysis of the excessive peak current. In this scheme, the machine side converter (MSC) controller adjusts the electromagnetic power according to the power transmitted to the grid by the grid side converter (GSC). Meanwhile, it converts the unbalanced power on the dc-link into the rotor kinetic energy, avoiding the dc-link overvoltage. The GSC controller can not only ensure that the three-phase inverter currents are in the maximum safe range that the converters can bear, but also provide reactive power support for the grid. Furthermore, the fluctuations on dc bus voltage and output power can be eliminated effectively by using the GSC controller. The feasibility of the proposed scheme and the superiority over the traditional control schemes have been verified by simulations under different types of unbalanced voltage.

KEYWORDS:

1.      Unbalanced grid voltage

2.       Peak current

3.      Current limiting control

4.      Rotor kinetic energy

        Reactive power support

 SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Figure 1. The Simplified System Structure.

EXPECTED SIMULATION RESULTS:

Figure 2. (A)The Three-Phase Unbalanced Voltages With 3956 90_, 5636 􀀀30_, 5636 􀀀150_Under Case 1, (B) The

Three-Phase Unbalanced Voltages With 3956 86_, 5406 􀀀28_, 5886 􀀀148_ Under Case 2, (C) Wind Speed.

 

Figure 3. Control Performance Of Different Control Schemes Under Case 1 (A) Control Strategy I, (B) Control Strategy Ii, (C) Proposed Control Strategy.

 

Figure 4. Control Performance Of Different Control Schemes Under Case 2 (A) Control Strategy I, (B) Control Strategy Ii, (C) Proposed Control Strategy.

CONCLUSION:

This paper presents a new power and current limiting control of wind turbine based on PMSG for enhanced operation performance under unbalanced grid voltage. The contributions of this work mainly includes the following parts: 1) Based on the detailed analysis of the output current, a peak current limiting scheme is proposed to ensure the three-phase currents are within the safe range; 2) The unbalanced power in the system is converted into rotor kinetic energy, which solves the problem of dc bus overvoltage; 3) The fluctuations on dc bus voltage and output power are eliminated effectively. The advantages of the proposed scheme for this work are as follows: 1) No additional auxiliary equipment is needed, avoiding high costs; 2) There is no need to exchange the control functions of MSC controller and GSC controller, which avoids the problem of resetting the control parameters; 3) The control of three-phase inverter currents is realized in αβ coordinate system, without the separation of positive and negative sequence of current and complex rotating coordinate transformation, the structure is simple. The effectiveness and superiority of the proposed control strategy have been verified by comparing the simulation results with the other two control strategies under the two different grid faults.

REFERENCES:

[1] M. Qais, H. M. Hasanien, and S. Alghuwainem, ``Salp swarm algorithmbased TS-FLCs for MPPT and fault ride-through capability enhancement of wind generators,'' ISA Trans., vol. 101, pp. 211_224, Jun. 2020.

[2] M. A. Soliman, H. M. Hasanien, S. Alghuwainem, and A. Al-Durra, ``Symbiotic organisms search algorithm-based optimal control strategy for efficient operation of variable-speed wind generators,'' IET Renew. Power Gener., vol. 13, no. 14, pp. 2684_2692, Oct. 2019.

[3] H. M. Qais, M. H. Hasanien, and S. Alghuwainem, ``Enhanced whale optimization algorithm for maximum power point tracking of variable speed wind generators,'' Appl. Soft Comput. J., vol. 86, Jan. 2020, Art. no. 105937.

[4] S. M. Tripathi, A. N. Tiwari, and D. Singh, ``Grid-integrated permanent magnet synchronous generator based wind energy conversion systems: A technology review,'' Renew. Sustain. Energy Rev., vol. 51, pp. 1288_1305, Nov. 2015.

[5] H. Geng, L. Liu, and R. Li, ``Synchronization and reactive current support of PMSG-based wind farm during severe grid fault,'' IEEE Trans. Sustain. Energy, vol. 9, no. 4, pp. 1596_1604, Oct. 2018.

Peak Current Detection Starting Based Position Sensorless Control of BLDC Motor Drive for PV Array Fed Irrigation Pump

ABSTRACT:

 The generation of exact commutation to start the permanent magnet brushless direct current (PMBLDC) motor in position sensorless control mode is the most challenging task. A peak current detection starting algorithm based wide speed range position sensorless control for solar photovoltaic array fed PMBLDC motor drive for the irrigation water pumping is presented here. This starting algorithm controls the exact starting commutation along with the peak staring current. An elimination of position sensor and current sensor for rotor position estimation makes the implemented drive compact and cost effective for agricultural application. The operation of the drive is first tested with simulation and the reliability is tested in the laboratory prototype as well as in compact industrial product prototype with cost-effective digital signal processor. The robustness of the system is verifiedwith different simulation and test results at various operating conditions. The compact cost-effective solution fits perfect for low cost, demanding both irrigation and domestic water pumping.

 KEYWORDS:

1.      Incremental conductance (INC) maximum power point tracking (MPPT) algorithm

2.      Peak current detection based starting

3.      Permanent magnet brushless direct current (PMBLDC) motor drive

4.      Position sensorless control

5.      Water pumping

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Fig. 1. System configuration of position sensorless brushless dc motor drive.

 

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Solar PV array performance. (a) Steady-state and starting performance at 1000 W/m2 insolation. (b) Dynamic performance varying from 500 to 1000 W/m2.

Fig. 3. BLDC motor performance at sensorless scheme. (a) Zero starting and steady-state performance at 1000 W/m2 irradiance. (b) Dynamic performance varying from 500 to 1000 W/m2 irradiance.

 

CONCLUSION:

A starting peak current controlled, smooth start, robust position sensorless control of a PMBLDC motor has been presented for solar powered pumping. The applied starting method takes care of the high starting inrush current to secure a good lifespan of the drive as well as the PMBLDC motor. The reduction of the position sensors makes the system compact and cost effective. The reliability and robustness of the developed drive are verified with both laboratory and industrial product prototype using d-SPACE (1104) and TMS320F28377S DSP. The performance and efficiency of the solar MPPT and PMBLDC motor are captured using DSO and the same is presented here. It is seen that the efficiency of the solarMPPT is more than 99%. It is also observed that the starting method is reliable and effective to keep the initial starting current within the desired limit. A fast settling stable dynamic performance of the drive is also observed.

 

REFERENCES:

 

[1] A. Sen and B. Singh, “Peak current detection starting based position sensorless control of BLDCmotor drive for PV array fed irrigation pump,” in Proc. IEEE Int. Conf. Environ. Elect. Eng. Ind. Commercial Power Syst. Europe (EEEIC /I&CPS Europe), 2019, pp. 1–6.

[2] S. Jain, A. K. Thopukara, R. Karampuri, and V. T. Somasekhar, “A single-stage photovoltaic system for a dual-inverter-fed open-end winding induction motor drive for pumping applications,” IEEE Trans. Power Electron., vol. 30, no. 9, pp. 4809–4818, Sep. 2015.

[3] L. An and D. D. Lu, “Design of a single-switch DC/DC converter for a PV-battery-poweredpumpsystem withPFM+PWMcontrol,” IEEE Trans. Ind. Electron., vol. 62, no. 2, pp. 910–921, Feb. 2015.

[4] J. V. M. Caracas, G. d. C. Farias, L. F. M. Teixeira, and L. A. d. S. Ribeiro, “Implementation of a high-efficiency, high-lifetime, and low-cost converter for an autonomous photovoltaic water pumping system,” IEEE Trans. Ind. Appl., vol. 50, no. 1, pp. 631–641, Jan./Feb. 2014.

[5] T.-H. Kim and M. Ehsani, “Sensorless control of the BLDC motors from near-zero to high speeds,” IEEE Trans. Power Electron., vol. 19, no. 6, pp. 1635–1645, Nov. 2004.

Maximum Power Point Tracking for Wind Turbine Using Integrated Generator-Rectifier Systems

ABSTRACT:

 Offshore wind is a rapidly growing renewable energy resource. Harvesting offshore energy requires multimegawatt wind turbines and high efficiency, high power density, and reliable power conversion systems to achieve a competitive levelized cost of electricity. An integrated system utilizing one active and multiple passive rectifiers with a multi-port permanent magnet synchronous generator is a promising alternative for an electro-mechanical power conversion system. Deployment of the integrated systems in offshore wind energy requires maximum power point tracking (MPPT) capability, which is challenging due to the presence of numerous uncontrolled passive rectifiers. This paper shows feasibility of MPPT based on a finding that the active rectifier d-axis current can control the total system output power. The MPPT capability opens up opportunities for the integrated systems in offshore wind applications.

KEYWORDS:

1.      Power conversion

2.      Ac-dc power conversion

3.       Rectifiers

4.      Dc power systems

5.      Wind energy

6.      Maximum power point trackers

7.      Wind energy generation

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

Figure 1. (a) Wind turbine power-point tracking architecture: the prime mover is a variable-speed wind turbine. The turbine shares a common shaft with the multi-port PMSG. Ac power is converted to dc by an integrated generator-rectifier system. The dc output is connected to a stiff dc interface. The integrated generator-rectifier system performs maximum power-point tracking to extract the turbine maximum power.

 EXPECTED SIMULATION RESULTS:

 

Figure 2. (a) (Top plot) The active rectifier d-axis and q-axis currents track the reference command, presented by the dotted lines. The dc-bus current varies accordingly by changing the d-axis current, leading to a change in the dc-bus power (bottom plot). (b) The relationship between dc-bus power and active-rectifier d-axis current acquired from the simulation model (recorded by the markers) matches the theoretical analysis (plotted by the lines using equation (6)).

 

Figure 3. Waveforms to illustrate the system MPPT capability. (a) At each wind speed, the turbine speed (solid-blue line) successfully tracks the optimal speed to generate maximum power. (b) The dc-bus power and the turbine mechanical power versus time. (c) The d-axis and q-axis currents to achieve MPPT.

 

 

 

Figure 4. Generator phase-A back emf, phase-A current, and power of the passive and active rectifiers at different operating speeds. (a) Sinusoidal and phase-shifted back emfs at the rated generator speed. (b) The corresponding phase-A currents. (c) Sharing of PMSG input power between ac ports powering active versus passive rectifiers. (d) Back emfs at the minimum operating speed that is equal to 55% the rated speed. (e) Phase-A currents corresponding to the minimum speed. (f) Power sharing between the ac ports powering active and passive rectifiers at the minimum operating speed.

 

CONCLUSION:

This paper presents an MPPT methodology for an integrated generator-rectifier system. An analytical relationship between the dc-bus power and the active rectifier d-axis current is established and validated using both simulation and experiment. A cascaded control architecture is proposed for practical implementation. The inner loop comprises PI current controllers with feed-forward terms, while the outer loop is a PI power controller. Satisfactory power tracking performance has been accomplished. The power flow control enables the wind turbine MPPT through controlling the dc-bus power. This capability opens up opportunities for the integrated generator rectifier systems in wind energy applications.

REFERENCES:

[1] P. Huynh, S. Tungare, and A. Banerjee, “Maximum power point tracking for wind turbine using integrated generator-rectifier systems,” in 2019 IEEE Energy Conversion Congress and Exposition (ECCE), Sep. 2019, pp. 13–20.

[2] D. S. Ottensen, “Global offshore wind market report,” Norweigian Energy Partner, Tech. Rep., 2018.

[3] C. Bak, R. Bitsche, A. Yde, T. Kim, M. H. Hansen, F. Zahle, M. Gaunaa, J. P. A. A. Blasques, M. Døssing, J.-J. W. Heinen et al., “Light rotor: The 10-MW reference wind turbine,” in EWEA 2012-European Wind Energy Conference & Exhibition. European Wind Energy Association (EWEA), 2012.

[4] P. Higgins and A. Foley, “The evolution of offshore wind power in the united kingdom,” Renewable and sustainable energy reviews, vol. 37, pp. 599–612, 2014.

[5] W. Musial, P. Beiter, P. Spitsen, J. Nunemaker, and V. Gevorgian, “2018 offshore wind technologies market report,” National Renewable Energy Laboratory, https://www.energy.gov/eere/wind/downloads/2018- offshore-wind-market-report, Tech. Rep., 2018.

Investigation of Voltage Sags Effects on ASD and Mitigation using ESRF theory-based DVR

ABSTRACT:

 Voltage sag is a frequently occurring power quality disturbance in the industries equipped with adjustable speed drives (ASD). A detailed investigation of voltage sag effects on ASD performance with the novel mathematical analyses to estimate the ASD parameters during different types of voltage sag is discussed in this article. The effects of voltage sags are mitigated using an enhanced synchronous reference frame (ESRF) theory-based dynamic voltage restorer (DVR). The working principle of the ESRF theory-based DVR during sag is also described. The investigation of the effects of type A, type B and type F voltage sags on ASD parameters are verified using the simulation and the experimental studies. Further, these effects are mitigated by the ESRF theory-based DVR using the developed simulation and experimental models. The ESRF controller of DVR is working effectively during voltage sags by improving its transient response, which tightly regulates the DC link voltage of ASD around its reference value. Also, the steady state response of DVR is enhanced during severe voltage sag, which further validates the ability of the ESRF theory-based DVR. This type of improved performance of ASD during voltage sags cannot be obtained using other existing SRF theories of the DVR.

KEYWORDS:

1.      Adjustable speed drives

2.      DC-link voltage

3.      Symmetrical sag

4.      Unsymmetrical sag

5.      Dynamic voltage restorer

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 

 

Fig. 1. Circuit diagram of DVR with ASD system.

 EXPECTED SIMULATION RESULTS:

Fig. 2. Simulation results of ASD during TAVS, TBVS and TFVS.

 

Fig. 3. Simulation results (a) ASD performance during severe TBVS and (b) RMS input line current.

Fig. 6. Comparison of the simulation results of the SRF [24,26] and the ESRF controller. (a) DC-link voltage of ASD and (b) Speed of the motor.

 

Fig. 7. Simulation results of the ESRF theory-based DVR during voltage swell. (a) PCC, DVR and ASD R-phase RMS voltages and (b) DC-link voltage of ASD.

CONCLUSION:

A detailed investigation of ASD performance under TAVS, TBVS and TFVS is presented in this article. A novel mathematical analysis to evaluate the ASD parameters during different types of voltage sag with various sag magnitudes is presented in this article. The initial effect of any voltage sag occurs on ASD is a drop in the DC-link voltage, which results in the fluctuation of stator current, torque and speed of the motor. From the mathematical analyses, simulation results and experimental results, it is observed that the ASD performance affects more severely due to TAVS. However, the most frequently occurring TBVS can also halt the operation of ASD. It can be inferred from the experimental study that the effects of voltage sag on ASD performance depend on its loading condition, type of sag and sag magnitude. The ESRF theory-based DVR is used to regulate the DC-link voltage of ASD to its reference value during the sag period, which results in the constant speed of the motor. Moreover, the ESRF controller enhanced the transient response compared to the other SRF theories. Also, the steady-state response of the DVR is improved during severe voltage sag (TAVS), which further validates the ability of the ESRF theory-based DVR to regulate the DC-link voltage of the ASD. The obtained simulation and experimental results proved that the ESRF theory-based DVR is able to regulate the speed of the motor around its reference value during 0.5 p.u. voltage sag for a minute. This proves the effectiveness of the ESRF controller technique over the existing SRF control theories of the DVR.

REFERENCES:

[1] N. Khatri, A. Jain, V. Kumar and R. R. Joshi, “Voltage sag assessment with respect to sensitivity of adjustable speed drives in distributed generation environment,” in proc. IEEE Int. Conf. on Computer, Communication and Control, Indore, India, 2015, pp. 1-6.

[2] Y. Liu, X. Xiao, X. Zhang and Y. Wang, “Multi-Objective Optimal STATCOM Allocation for Voltage Sag Mitigation,” in IEEE Trans. Pow. Del., vol. 35, no. 3, pp. 1410-1422, June 2020.

[3] Y. Wang, L. Deng, M. H. J. Bollen and X. Xiao, “Calculation of the Pointon- Wave for Voltage Dips in Three-Phase Systems,” in IEEE Trans. Pow. Del., vol. 35, no. 4, pp. 2068-2079, Aug. 2020.

[4] S. Jothibasu and M. K. Mishra, “A Control Scheme for Storageless DVR Based on Characterization of Voltage Sags,” in IEEE Trans. Pow. Del., vol. 29, no. 5, pp. 2261-2269, Oct. 2014.

[5] M. R. Alam, K. M. Muttaqi and T. K. Saha, “Classification and Localization of Fault-Initiated Voltage Sags Using 3-D Polarization Ellipse Parameters,” in IEEE Trans. Pow. Del., vol. 35, no. 4, pp. 1812-1822, Aug. 2020.SSSSSSSSSSS

Partial Power Conversion and High Voltage Ride-Through Scheme for a PV-Battery Based Multiport Multi-Bus Power Router

ABSTRACT:

 With the development of renewable energy technology, distributed power supply mode with multi energy and multi-directional power flow including utility grid, renewable energy and energy storage unit has gradually become a research hotspot. An AC/DC hybrid multi-port power routing (MPPR) system which based on partial power conversion (PPC) of dual DC buses is proposed in this paper. The photovoltaic (PV) port, the battery port and two DC voltage buses form a power router. PV maximum power point tracking (MPPT) and high-voltage ride through (HVRT) of the grid-tied inverter are implemented by the same auxiliary port voltage modulation. The PPC based PV conversion features that only the power determined by voltage difference between PV panel and the series connected DC bus is dealt with, which significantly reduces the loss compared to the full power conversion (FPC) for PV. The detailed control schemes of all converters and energy transmit are given. The simulation and experimental results verify the effectiveness of the proposed scheme.

 KEYWORDS:

1.      Partial power conversion

2.      Multi-port power routing

3.      High voltage ride-through

4.      PV-battery

5.      Grid-connected system

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

 

Figure 1. The MPPR Topology Of PV-Battery Grid-Connected System.

 

EXPECTED SIMULATION RESULTS:

 

Figure 2. Simulation Result Of Case I.

Figure 3. The Steady-State Waveform In 0-1s.

Figure 4. Simulation Result Of Case II.

CONCLUSION:

This article proposes a PV-battery based multi-port power routing. Compared with the traditional PV-battery grid-connected system, the proposed MPPR in this paper has two main characteristics implemented by one auxiliary port simultaneously: first is the partial power conversion of the DC/DC stage, which significantly improves the power transfer efficiency. Secondary, MPPR realizes HVRT on the premise of maintaining normal PV output, and auxiliary port is adaptive to the grid-side voltage swell by adjusting its voltage so as to improve the voltage level of three phase converter DC bus. The system can flexibly realize the power exchange between three ports, two DC buses and the grid.

REFERENCES:

 

[1] A. Sangwongwanich, Y. Yang, and F. Blaabjerg, ``High-performance con- stant power generation in grid-connected PV systems,'' IEEE Trans. Power Electron., vol. 31, no. 3, pp. 1822_1825, Mar. 2016.

[2] C. Zhong, Y. Zhou, X. Zhang, and G. Yan, ``Flexible power-point-tracking- based frequency regulation strategy for PV system,'' IET Renew. Power Gener., vol. 14, no. 10, pp. 1797_1807, Jul. 2020.

[3] H. Fathabadi, ``Improving the power ef_ciency of a PV power generation system using a proposed electrochemical heat engine embedded in the system,'' IEEE Trans. Power Electron., vol. 34, no. 9, pp. 8626_8633, Sep. 2019.

[4] Y. Liu, S. You, and Y. Liu, ``Study of wind and PV frequency control in U.S. power grids_EI and TI case studies,'' IEEE Power Energy Technol. Syst. J., vol. 4, no. 3, pp. 65_73, Sep. 2017.

[5] H. Sugihara, K. Yokoyama, O. Saeki, K. Tsuji, and T. Funaki, ``Economic and ef_cient voltage management using customer-owned energy storage systems in a distribution network with high penetration of photovoltaic systems,'' IEEE Trans. Power Syst., vol. 28, no. 1, pp. 102_111, Feb. 2013.