Wind Energy Fed UPQC System for Power Quality Improvement


The extensive use of non-linear loads in domestic, industrial and commercial services origin harmonic complications. Harmonics make malfunctions in profound equipment, voltage drop across the network, conductor heat increases and overvoltage through resonance. All these problems can be remunerated by using Unified Power Quality Controller (UPQC) and the operation of UPQC depends upon the available voltage across capacitor present in dc link.

If the capacitor voltage is maintained constant then it gives satisfactory performance. The proposed research is basically on designing of Wind energy fed to the dc link capacitor of UPQC so as to maintain proper voltage across it and operate the UPQC for power quality analysis. The proposed technique is the grouping of shunt and series Active Power Filter (APF) to form UPQC

Which is fed wind energy system and connected to grid for better response in the output. In this paper, the simulation model of series APF, shunt APF, UPQC and Wind energy with UPQC are design in Matlab. The proposed Wind energy-UPQC is design in Matlab simulation for reduction of voltage sag, swell, harmonics in load current and compensation of active and reactive power.


  1. Harmonics
  2. Power quality
  3. Unified power quality conditioner
  4. Wind energy



The advantage of wind energy system is to retain a constant voltage of 600 volts across the DC-Link capacitor. In this work the wind energy with boost converter output is 600V and simulation of wind energy-UPQC maintains constant voltage of 600V when Sag, Swell and Interruption occur.

It also reduces the harmonics content to 2.33% if any nonlinear load is associated as shown in Figure 19. Hence the proposed scheme can regulate active and reactive power injection to the grid and compensate voltage sag and swell in addition to the other usual operation of UPQC effectible as the voltage across the dc link capacitor is maintained constant. Figure 20 shows DC link voltage.


[1] Carrasco JM, Franquelo LG, Bialasiewicz JT, Galván E, PortilloGuisado RC, Prats MM, León JI, Moreno-Alfonso N. Power-electronic systems for the grid integration of renewable energy sources: A survey. IEEE Transactions on industrial electronics. 2006; 53(4): 1002-1016.

[2] Samal S, Hota PK. Power Quality Improvement by Solar Photo-voltaic/Wind Energy Integrated System Using Unified Power Quality Conditioner. International Journal of Power Electronics and Drive Systems (IJPEDS). 2017; 8(3): 1424.

[3] Samal S, Hota PK. Power Quality Improvement by Solar Photo-voltaic/Fuel Cell Integrated System Using Unified Power Quality Conditioner. International Journal of Renewable Energy Research (IJRER). 2017; 7(4): 2075-84.

[4] Samal S, Hota PK. Design and analysis of solar PV-fuel cell and wind energy based microgrid system for power quality improvement. Cogent Engineering. 2017; 4(1): 1402453.

[5] Basu M, Das SP, Dubey GK. Comparative evaluation of two models of UPQC for suitable interface to enhance power quality. Electric Power Systems Research. 2007; 77(7): 821-830.


 Power Quality Improvement in Utility Interactive Based AC-DC Converter Using Harmonic Current Injection Technique


This paper highlights the power quality issues and explains the corrective measures taken by means of hybrid front-end third harmonic current injection rectifiers. Here zig-zag transformer is used as the current injection device so that the advantages related to the zig-zag transformer is effectively utilized. The third harmonic current injection device along with three-level boost converter at the output stage will increase the DC-link voltage.

boost converter

With less boost inductance, generally half of the conventional boost converter inductance is sufficient to implement the proposed converter structure resulting in reduced ripple current and also the device rating is reduced by half of the output voltage. Moreover, the power quality is well improved using third harmonic current modulated front-end structure which is well proper for medium/higher power applications. The experimental prototype of hybrid front-end converter is developed in the laboratory to validate the MATLAB simulation results.


  1. Current modulation circuit
  2. Front-end rectifier
  3. Power quality
  4. PFC
  5. Third harmonic current injection
  6. Three-level boost converter
  7. THD
  8. Zig-zag transformer



Fig. 1. Schematic diagram of proposed front-end AC-DC converter


Fig. 2. Simulation results of input phase voltage, input phase current, input voltage and current, DC-link voltage, and DC current for the proposed front-end converter under load variations.

Fig. 3. Frequency spectrum of input line current ias at (a) Light load condition

(20%) (b) Full load condition (100%).

Fig. 4. Comparison of power quality indices with varying load of front-end AC-DC converter with six-pulse DBR (a) Variation of THD of input current with load and (b) Variation of PF of input current with load.


In this paper, a front-end AC-DC converter employed with third harmonic current injection circuit using a zig-zag transformer and three-level boost converter has implemented for medium and high-power applications. The three-level boost converter has completed with less boost inductance, an only half rating of the conventional boost converter inductance thereby resulting in less ripple current and also the device rating has reduced by half of the output voltage.

zig-zag transformer

The third order current harmonic reduction has achieved by the zig-zag transformer. With less attractive rating, only 20% of the load rating is enough to realize the zig-zag transformer. The proposed converter has modeled, designed and its performance was analyzed by MATLAB simulation under varying load conditions. An experimental setup has been developed, and the performance of the system is confirmed from the hardware results. The proposed scheme resulted in less input current and voltage THD and control PF close to unity. Also, the other power quality parameters such as displacement PF and misuse factor are well within the IEEE standards.


[1] Abraham I. Pressman, “Switching Power Supply Design,” McGraw-Hill, International Editions, New York, 1999.

[2] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey and D. P. Kothari, “A review of single-phase improved power quality AC-DC converters,” IEEE Trans. on Ind. Electron., vol. 50, no. 5, pp. 962-981, Oct. 2003.

[3] J. I. Itoh and I. Ashida, “A Novel Three-Phase PFC Rectifier Using a Harmonic Current Injection Method,” IEEE Trans. on Power Electron., vol. 23, no. 2, pp. 715-722, March 2008.

[4] N. Vazquez, H. Rodriguez, C. Hernandez, E. Rodriguez and J. Arau, “Three-Phase Rectifier With Active Current Injection and High Efficiency,” IEEE Trans. on Ind. Electron., vol. 56, no. 1, pp. 110-119, Jan. 2009.

[5] H. Y. Kanaan and K. Al-Haddad, “Three-Phase Current-Injection Rectifiers: Competitive Topologies for Power Factor Correction,” IEEE Ind. Electron. Magazine, vol. 6, no. 3, pp. 24-40, Sept. 2012.

Standalone Operation of Modified Seven-Level Packed U-Cell (MPUC) Single-Phase Inverter


In this paper the standalone operation of the modified seven-level Packed U-Cell (MPUC) inverter is given and consider. The MPUC inverter has two DC sources and six switches, which cause seven voltage levels at the output. Compared to cascaded H-bridge and neutral point clamp multilevel inverters, the MPUC inverter produce a higher number of voltage levels using fewer components. The experimental results of the MPUC prototype validate the allocate operation of the multilevel inverter handle with various load types including motor, linear, and nonlinear ones. The design considerations, including output AC voltage RMS value, switching frequency, and switch voltage rating, as well as the harmonic analysis of the output voltage waveform, are taken into account to prove the advantages of the introduced multilevel inverter.


1. Multilevel inverter
2. Packed u-cell
3. Power quality
4. Multicarrier PWM
5. Renewable energy conversion



Figure 1. Single-phase seven-level MPUC inverter in standalone mode of operation


Figure 2. Seven-level MPUC inverter output voltage and current with DC source voltages. Ch1: V1,
Ch2: V2, Ch3: Vab, Ch4: il.

Figure 3. One cycle of output voltage and gate pulses of MPUC inverter switches. Ch1: Vab, Ch2: T1
gate pulses, Ch3: T2 gate pulses, Ch4: T3 gate pulses

Figure 4. MPUC inverter switches’ voltage ratings. Ch1: Vab, Ch2: T1 voltage, Ch3: T2 voltage, Ch4:
T3 voltage. and nonlinear). The step-by-step process for connecting loads is depicted in Figure 7, which show

Fig.5. Test results when a nonlinear load is connected to the MPUC inverter.Ch1 :Vab :Ch4 :il.

Figure 6. Output voltage and current waveform of MPUC inverter when different loads are added
step by step. Ch1: Vab, Ch4: il. (A) Transient state when nonlinear load is added to the RL load (left)
and after a while a motor load is added to the system (right); (B) steady state when a nonlinear load is
added to the RL load (left) and after a while a motor load is added to the system (right).

Figure 7. Voltage and current waveform of MPUC inverter with RMS calculation for 120 V system.


In this paper a redesign PUC inverter topology has been presented and studied experimentally. The proposed MPUC inverter can produce a seven-level voltage waveform at the output with low harmonic contents. The associated switching algorithm has been create and achieve on the introduced MPUC topology with reduced switching frequency aspect. Switches’ frequencies and ratings have been investigated experimentally to validate the good dynamic performance of the proposed topology. Moreover, the comparison of MPUC to the CHB multilevel inverter showed other advantages of the proposed multilevel inverter topology, including fewer components, a lower manufacturing price, and a smaller package due to reduced filter size.
Author improvement: All authors improvement equally to the work presented in this paper.
Funding: This research received no external funding.
competition of Interest: The authors declare no competition of interest.


1. Bose, B.K. Multi-Level Converters; Multidisciplinary Digital Publishing Institute: Basel, Switzerland, 2015.
2. Mobarrez, M.; Bhattacharya, S.; Fregosi, D. Implementation of distributed power balancing strategy with a layer of supervision in a low-voltage DC microgrid. In Proceedings of the 2017 IEEE Applied Power Electronics Conference and Exposition (APEC), Tampa, FL, USA, 26–30 March 2017; pp. 1248–1254.
3. Franquelo, L.G.; Rodriguez, J.; Leon, J.I.; Kouro, S.; Portillo, R.; Prats, M.A.M. The age of multilevel converters arrives. IEEE Ind. Electron. Mag. 2008, 2, 28–39. [CrossRef]
4. Malinowski, M.; Gopakumar, K.; Rodriguez, J.; Perez, M.A. A survey on cascaded multilevel inverters. IEEE Trans. Ind. Electron. 2010, 57, 2197–2206. [CrossRef]
5. Nabae, A.; Takahashi, I.; Akagi, H. A new neutral-point-clamped PWM inverter. IEEE Trans. Ind. Appl. 1981,5, 518–523. [CrossRef]

Control and Implementation of a Standalone Solar Photo-Voltaic Hybrid System


A control algorithm for a standalone solar photovoltaic (PV)-diesel-battery hybrid system is achive in this paper. The proposed system deals with the irregular nature of the energy produce by the PV array and it also provides power quality improvement. The PV array is combined through a DC-DC boost converter and controlled using a maximum power point tracking (MPPT) algorithm to obtain the maximum power under varying operating conditions.

The battery energy storage system (BESS) is combined to the diesel engine generator (DG) set for the regulate load management and power flow within the system. The access based control algorithm is used for load balancing, harmonics elimination and reactive power compensation under three phase four-wire linear and nonlinear loads. A four-leg voltage source converter (VSC) with BESS also provides neutral current compensation. The performance of proposed standalone hybrid system is designed under different loading conditions experimentally on a developed prototype of the system.


  1. Admittance based control algorithm
  2. BESS
  3. DG set
  4. Four-leg VSC
  5. Neutral current compensation
  6. Power quality
  7. Solar photovoltaic array
  8. Standalone system



Fig. 1. Schematic diagram of the proposed system


Fig. 2. Performance of proposed system under unbalance nonlinear load


 The access based control technique has been used for a PV-diesel-battery hybrid system for an continuous power supply and power quality improvement. The incremental based MPPT algorithm has forwarded maximum solar array power under varying conditions of temperature and insolation distribution.

The technique has been show to eliminate harmonics, load balancing and to provide neutral current compensation by incorporating four-leg VSC in the system. The PCC voltage and frequency have been maintained constant. Satisfactory performance of the system has been observed through test results obtained for steady state and dynamic conditions under both linear/nonlinear loads.


[1] Z. Jiang, “Power Management of Hybrid Photovoltaic-Fuel Cell Power Systems”, Proc. of IEEE Power Engg. Society General Meeting, Montreal Quebec, Canada, 2006.

[2] A. Naik, R.Y. Udaykumar and V. Kole, “Power management of a hybrid PEMFC-PV and Ultra capacitor for stand-alone and grid connected applications”, Proc. of IEEE Int. Conf. Power Electron. Drives and Energy Sys. (PEDES), 2012, pp. 1-5.

[3] J. Philip, C. Jain, , K. Kant, B. Singh, S. Mishra, A. Chandra and K. Al- Haddad “Control and implementation of a standalone solar photo-voltaic hybrid system”, Proc. of IEEE Industry Applications Society Annual Meeting, Addison, TX, 18- 22 Oct. 2015, pp.1-8.

[4] J. Philip, B. Singh and S. Mishra, “Design and operation for a standalone DG-SPV-BES microgrid system”, Proc. of 6thIEEE Power India Int. Conf. (PIICON), Delhi, 5-7 Dec, 2014, pp.1-6.

Artificial Neural Network based Dynamic Voltage Restorer for Improvement of Power Quality


Dynamic Voltage Restorer (DVR) is a custom power device used as an effective solution in protecting sensitive loads from voltage disturbances in power distribution systems. The efficiency of the control technique, that conducts the switching of the inverters, determines the DVR efficiency.Proportional-Integral-Derivative (PID) control is the general technique to do that. The power quality restoration capabilities of this controller are limited, and it produces significant amount of harmonics – all of which stems from this linear technique’s application for controlling non-linear DVR. As a solution, this paper proposes an Artificial Neural Network (ANN) based controller for enhancing restoration and harmonics suppression capabilities of DVR. A detailed comparison of Neural Network controller with PID driven  controller and Fuzzy logic driven controller is also illustrated, where the proposed controller demonstrated superior performance with a mere 13.5% Total Harmonic Distortion.

  1. Power quality
  2. Dynamic Voltage Restorer (DVR)
  3. PID
  4. Fuzzy logic
  5. Artificial Neural Network (ANN)



 Fig. 1. Block diagram of the proposed DVR system to mitigate voltage instabilities.


Fig. 2. Three phase sag mitigation based on ANN controlled DVR. (a) Instantaneous voltage at stable condition; (b) Instantantaneous voltage when sag occurs; (c) Voltage required to mitigate voltage sag; (d) Output voltage of the inverter circuit; (e) Generated PWM for inverter; (f) Instantaneous voltage after voltage restoration.

Fig. 3. Restored Voltage Using (a) PID controller; (b) Fuzzy controller; (c) ANN controller; (d)THD comparison: the least THD can be seen at ANN based DVR, the range of the harmonics is also truncated by a huge amount by this method.


 DVRs are a popular choice for enhancing power quality in power systems, with an array of control system on offer to drive these devices. In this paper, application of ANN to operate DVR for providing better performance than existing systems to mitigate voltage sag, swell, and harmonics has been demonstrated. Problem statement and theoretical background, structure of the proposed method, training procedure of the ANN used have been described in detail. Simulation results showing the DVR performance during voltage sag have been presented. Comparison of the proposed method with the popular PID controller, and nonlinear Fuzzy controller has been carried out, where the proposed ANN controller appeared as the best option to restore system voltage while mitigating THD to the greatest extent.


[1] M. H. Bollen, R. Das, S. Djokic, P. Ciufo, J. Meyer, S. K. Rönnberg, et al., “Power quality concerns in implementing smart distribution-grid applications,” IEEE Transactions on Smart Grid, vol. 8, pp. 391-399, 2017.

[2] V. Khadkikar, D. Xu, and C. Cecati, “Emerging Power Quality Problems and State-of-the-Art Solutions,” IEEE Transactions on Industrial Electronics, vol. 64, pp. 761-763, 2017.

[3] X. Liang, “Emerging power quality challenges due to integration of renewable energy sources,” IEEE Transactions on Industry Applications, vol. 53, pp. 855-866, 2017.

[4] T. Sutradhar, J. R. Pal, and C. Nandi, “Voltage Sag Mitigation by using SVC,” International Journal of Computer Applications, vol. 71, 2013.

[5] F. M. Mahdianpoor, R. A. Hooshmand, and M. Ataei, “A new  approach to multifunctional dynamic voltage restorer implementation for emergency control in distribution systems,” IEEE transactions on power delivery, vol. 26, pp. 882-890, 2011.

Powеr Quality Improvement In Powеr Systеm By Using SVPWM Based Static Synchronous Sеriеs Compеnsator


 Power quality improvement is an important issue in power system. Flexible AC Transmission (FACTS) devices are commonly used for solving problems related to power quality and improving it. In this paper a synchronous static series compensator (SSSC) is used for control and modulation of power flow in a transmission line. The Pulse Width Modulation (PWM) and SVPWM control techniques are employed in SSSC. The active performance of SSSC is evaluated using Matlab/Simulink environment. The simulation results validate that the power quality is enhanced properly using SSSC.


  1. Power Quality
  2. FACTS
  3. PWM
  4. SVPWM
  5. SSSC




 Figure 1. Functional model of SSSC.



 Figure 2. (a) Source voltage (b) Source current without SSSC.

Figure 3. (a) Load voltage (b) Load current without SSSC.

Figure 4. (a) Source voltage (b) Source current with SSSC.

Figure 5. (a) Load voltage (b) Load current with SSSC.

Figure 6. (a) Source voltage (b) Source current with SVPWM SSSC.

Figure 7. (a) Load voltage (b) Load current with SVPWM SSSC.

Figure 8. FFT analysis of (a) Source voltage (b) Source current-without SSSC.

Figure 9. FFT analysis of (a) Load voltage (b) Load current –without SSSC.

Figure 10. FFT analysis of (a) Source voltage (b) Source current with SSSC.

Figure 11. FFT analysis of (a) Load voltage (b) Load current with SSSC.

Figure 12. FFT analysis of (a) source voltage and (b) source current using SVPWM SSSC.

Figure 13. FFT analysis of (a) Load voltage and (b) Load current using SVPWM SSSC.


 In this paper the problem of modulation and control of power flow in transmission line is carried out by using SSSC with PWM and SVPWM techniques. The performance of SSSC is validated using Matlab/Simulink software. Thus, simulation results and THD analysis shows that by using SVPWM based SSSC power quality gets improved more as compared to the SPWM based SSSC. Hence SVPWM technique proves better as compared to that of the SPWM technique for power quality improvement.


[1] N.G. Hingorani and L. Gyugyi, “Undеrstanding FATCS concеpts andtеchnology of flеxiblе ac transmission systеm”,Nеw York, NY: IЕЕЕ prеss, 2000.

[2] “Static Synchronous Compensator,” CIGRE, Working group 14.19, 1998.

[3] Laszlo Gyugyi, Colin D. Schaudеr, and Kalyan K. Sеn, “static synchronous sеriеs compеnsator: a solid-statе approach to thе sеriеs compеnsation of transmission linеs”, IЕЕЕ Transactions on powеr dеlivеry, Vol. 12, No. 1, January 1997.

[4] Vaishali M. Morе, V.K. Chandrakar, “Powеr systеm pеrformancеs improvеmеnt by using static synchronous sеriеs compеnsator”, intеrnational confеrеncе on Advancеs in Еlеctrical, Еlеctronics,Informantion, Communication and Bio-Informatics 978-1-4673-9745-2©2016 IЕЕЕ.

[5] M. Farhani, “Damping of subsynchronous oscillations in powеr systеm by using static synchronous sеriеs compеnsator”,IЕT Gеnr. Distrib.vol.6.Iss.6.pp.539-544,2012.

Integrated Photovoltaic and Dynamic Voltage Restorer System Configuration


This paper presents a new system structure for integrating a grid-connected photo voltaic (P V) system together with a self-supported dynamic voltage restorer (DVR). The proposed system termed as a “six-port converter,” consists of nine semiconductor switches in total. The proposed configuration retains all the essential features of normal P V and DVR systems while reducing the overall switch count from twelve to nine. In addition, the dual functionality feature significantly enhances the system robustness against severe symmetrical/asymmetrical grid faults and voltage dips. A detailed study on all the possible operational modes of six-port converter is presented. An appropriate control algorithm is developed and the validity of the proposed configuration is verified through extensive simulation as well as experimental studies under different operating conditions.


  1. Bidirectional power flow
  2. Distributed power generation
  3. Photovoltaic (PV) systems
  4. Power quality
  5. Voltage control




 Fig. 1. Proposed integrated PV and DVR system configuration.


Fig. 2. Simulation results: operation of proposed system during health grid mode (PV-VSI: active and DVR-VSI: inactive). (a) Vpcc; (b) PQload; (c) PQgrid; (d) PQpv-VSI; and (e) PQdvr-VSI.

Fig. 3. Simulation results: operation of proposed system during fault mode (PV-VSI: inactive and DVR-VSI: active). (a) Vpcc; (b) Vdvr; (c) Vload; (d) PQload; (e) PQgrid; (f) PQpv-VSI; and (g) PQdvr-VSI.

Fig. 4. Simulation results: operation of proposed system during balance three phase sag mode (PV-VSI: active and DVR-VSI: active). (a) Vpcc; (b) Vdvr-VSI; (c) Vload; (d) PQgrid; (e) PQpv-VSI; and (f) PQdvr-VSI.

Fig. 5. Simulation results: operation of proposed system during unbalanced sag mode (PV-VSI: active and DVR-VSI: active). (a) Vpcc; (b) Vdvr-vsi; (c) Vload; (d) PQgrid; (e) PQpv-VSI; and (f) PQdvr-VSI.

Fig. 6. Simulation results: operation of proposed system during inactive PV plantmode (PV-VSI: active and DVR-VSI: active). (a) Vpcc; (b) Vload; (c) Vdc; (d) PQload; (e) PQdvr-VSI; and (f) PQpv-VSI.


 In this paper, a new system configuration for integrating a conventional grid-connected P V system and self supported DVR is proposed. The proposed configuration not only exhibits all the functionalities of existing P V and DVR system, but also enhances the DVR operating range. It allows DVR to utilize active power of P V plant and thus improves the system robustness against sever grid faults. The proposed configuration can operate in different modes based on the grid condition and P V power generation. The discussed modes are healthy grid mode, fault mode, sag mode, and P V inactive mode. The comprehensive simulation study and experimental validation demonstrate the effectiveness of the proposed configuration and its practical feasibility to perform under different operating conditions. The proposed configuration could be very useful for modern load centers where on-site P V generation and strict voltage regulation are required.


[1] R. A. Walling, R. Saint, R. C. Dugan, J. Burke, and L. A. Kojovic, “Summary of distributed resources impact on power delivery systems,” IEEE Trans. Power Del., vol. 23, no. 3, pp. 1636–1644, Jul. 2008.

[2] C. Meza, J. J. Negroni, D. Biel, and F. Guinjoan, “Energy-balance modeling and discrete control for single-phase grid-connected PV central inverters,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2734–2743, Jul.2008.

[3] T. Shimizu, O. Hashimoto, and G. Kimura, “A novel high-performance utility-interactive photovoltaic inverter system,” IEEE Trans. Power Electron., vol. 18, no. 2, pp. 704–711, Mar. 2003.

[4] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of single-phase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind.Appl., vol. 41, no. 5, pp. 1292–1306, Sep./Oct. 2005.

[5] T. Esram, J. W. Kimball, P. T. Krein, P. L. Chapman, and P. Midya, m“Dynamic maximum power point tracking of photovoltaic arrays using ripple correlation control,” IEEE Trans. Power Electron., vol. 21, no. 5, pp. 1282–1291, Sep. 2006.

Electric Spring for Voltage and Power Stability and Power Factor Correction


Electric Spring (ES), a new smart grid technology, has earlier been used for providing voltage and power stability in a weakly regulated/stand-alone renewable energy source powered grid. It has been proposed as a demand side management technique to provide voltage and power regulation. In this paper, a new control scheme is presented for the implementation of the
electric spring, in conjunction with non-critical building loads like electric heaters, refrigerators and central air conditioning system. This control scheme would be able to provide power factor correction of the system, voltage support, and power balance for the critical loads, such as the building’s security system, in addition to the existing characteristics of electric spring of voltage and power stability. The proposed control scheme is compared with original ES’s control scheme where only reactive-power is injected. The improvised control scheme opens new avenues for the utilization of the electric spring to a greater extent by providing voltage and power stability and enhancing the power quality in the renewable energy powered microgrids


Fig. 1. Electric Spring in a circuit


Fig. 2. Over-voltage, Conventional ES: Power Factor of system (ES turned on at t = 0.5 sec)

Fig. 3. Over-voltage, Conventional ES: Active and Reactive power across critical load, non-critical load, and electric spring (ES turned on at t=0.5 sec)

Fig. 4 Under-voltage, Conventional ES: RMS Line voltage, ES Voltage, and Non-Critical load voltage (ES turned on at t=0.5 sec)

Fig. 5. Under-voltage, Conventional ES: Power Factor of system (ES turned on at t = 0.5 sec)

Fig. 6. Under-voltage, Conventional ES: Active and Reactive power across critical load, non-critical load, and electric spring (ES turned on at t=0.5 sec)

Fig. 7. Over-voltage, Improvised ES: RMS Line voltage, ES Voltage, and Non-Critical load voltage (ES turned on at t=0.5 sec)

Fig. 8. Over-voltage, Improvised ES: Power Factor of system (ES turned on at t = 0.5 sec)


In this paper as well as earlier literature s, the Electric Spring
was demonstrated as an ingenious solution to the problem of
voltage and power instability associated with renewable energy
powered grids. Further in this paper, by the implementation of
the proposed improvised control scheme it was demonstrated
that the improvised Electric Spring (a) maintained line voltage
to reference voltage of 230 Volt, (b) maintained constant
power to the critical load and (c) improved overall power
factor of the system compared to the conventional ES. Also,
the proposed ‘input-voltage-input-current’ control scheme is
compared to the conventional ‘input-voltage’ control. It was
shown, through simulation and hardware-in-loop emulation,
that using a single device voltage and power regulation and
power quality improvement can be achieved.

Control Scheme

It was also shown that the improvised control scheme has merit over the conventional ES with only reactive power injection.
Also, it is proposed that electric spring could be embedded
in future home appliances. If many non-critical loads in the
buildings are equipped with ES, they could provide a reliable
and effective solution to voltage and power stability and in sit u
power factor correction in a renewable energy powered
micro-grids. It would be a unique demand side management
(D S M) solution which could be implemented without any
reliance on information and communication technologies.


[1] S. Y. Hui, C. K. Lee, and F. F. Wu, “Electric springs – a new smart
grid technology,” IEEE Transactions on Smart Grid, vol. 3, no. 3, pp.
1552–1561, Sept 2012.
[2] S. Hui, C. Lee, and F. WU, “Power control circuit and
method for stabilizing a power supply,” 2012. [Online]. Available:
[3] C. K. Lee, N. R. Ch a u d h u r i, B. Ch a u d h u r i, and S. Y. R. Hui, “Droop
control of distributed electric springs for stabilizing future power grid,”
IEEE Transactions on Smart Grid, vol. 4, no. 3, pp. 1558–1566, Sept
[4] C. K. Lee, B. Ch a u d h u r i, and S. Y. Hui, “Hardware and control
implementation of electric springs for stabilizing future smart grid with
intermittent renewable energy sources,” IEEE Journal of Emerging and
Selected Topics in Power Electronics, vol. 1, no. 1, pp. 18–27, March
[5] C. K. Lee, K. L. Che n g, and W. M. N g, “Load characterization of electric
spring,” in 2013 IEEE Energy Conversion Congress and Exposition, Sept
2013, pp. 4665–4670.

Power Quality Enhancement in Residential Smart Grids through Power Factor Correction Stages

Power Quality Enhancement titles


The proliferation of non-linear loads and the increasing penetration of Distributed Energy Resources (D ER) in Medium-Voltage (M V) and Low-Voltage (L V) distribution grids, make it more difficult to maintain the power quality levels in residential electrical grids, especially in the case of weak grids. Most household appliances contain a conventional Power Factor Corrector (PFC) rectifier, which maximizes the load Power Factor (PF) but does not contribute to the regulation of the voltage Total Harmonic Distortion (TH D V ) in residential electrical grids.


manuscript proposes a modification for PFC controllers by adapting the operation mode depending on the measured TH D V . As a result, the PF Cs operate either in a low current Total Harmonic Distortion (TH DI ) mode or in the conventional resistor emulator mode and contribute to the regulation of the TH D V and the PF at the distribution feeders. To prove the concept, the modification is applied to a current sensor less Non-Linear Controller (N LC) applied to a single-phase Boost rectifier. Experimental results show its performance in a PFC front-end stage operating in Continuous Conduction Mode (CC M) connected to the grid with different TH D V.



 Fig. 1. Residential L V grid with household appliances feed through conventional AC/DC stages (without the proposed operation mode selector) and the proposed P Q E controller.



Fig. 2. Experimental results of P Q E PFC at 50 Hz. Voltage and current wave forms in a) resistor emulator mode (k = 0), b) sinusoidal current mode (k = 1) and c) measured spectra in both operation modes.

Fig. 3. Experimental results of  P Q E PFC at 60 Hz. Voltage and current wave forms in a) resistor emulator mode (k = 0), b) sinusoidal current mode (k = 1) and c) measured spectra in both operation modes.

Fig. 4. Experimental results of P Q E PFC at 400 Hz. Voltage and current wave forms in a) resistor emulator mode (k = 0), b) sinusoidal current mode (k = 1) and c) measured spectra in both operation modes.


The consequence on the electrical power quality of connecting household appliances to the grid through PFC stages has been assessed considering different TH D V scenarios. As has been shown in (17) and (23), there are conditions under which sinusoidal current consumption results in better PF at the PC C than with resistor emulator behavior, commonly assumed to be ideal for PFC stages. A modification of the carrier signal of N LC controllers applied to PFC stages is designed to impress sinusoidal input current despite the input voltage distortion. The line current estimation with no interaction with the power stage implements the N LC with high noise immunity. The digital implementation of the non-linear controller is appropriate to define the carrier and to include additional reduction of the current distortion depending on the application.

P Q E controller

The P Q E controller can be applied to mitigate the effect of nonlinear loads within household appliances on residential electrical grids. The operation mode of the digital controller can be autonomously adjusted through the locally measured TH D V , without extra circuitry. The user or a TH D V threshold detection selects the convenient behavior (either resistor emulator or pure sinusoidal current). Experimental results obtained with high TH D V (above 5 %) confirm the feasibility of the P Q E controller in both sinusoidal current and resist i v e emulator modes.


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[2] Y. J. Wang, R. M. O’Connell, and G. Brownfield, “Modeling and prediction of distribution system voltage distortion caused by nonlinear residential loads,” IEEE Trans. Power Del., vol. 16, D OI 10.1109/61.956765, no. 4, pp. 744–751, Oct. 2001.

[3] H. Ora e e, “A quantitative approach to estimate the life expectancy of motor insulation systems,” IEEE Trans. Die l e ct r. Elect r. In s u l., vol. 7, D OI 10.1109/94.891990, no. 6, pp. 790–796, Dec. 2000.

[4] D. Fab i an i and G. C. Mont an a r i, “The effect of voltage distortion on ageing acceleration of insulation systems under partial discharge activity,” IEEE Elect r. Ins u l. Mag., vol. 17, D OI 10.1109/57.925300, no. 3, pp. 24–33, May. 2001.

[5] T. J. Dion i s e and V. Lo r ch, “Harmonic filter analysis and redesign for a modern steel facility with two melt furnaces using dedicated capacitor banks,” in IEEE I AS Annual Meeting, vol. 1, D OI 10.1109/I AS.2006.256496, pp. 137–143, Oct. 2006.

Performance Improvement of DVR by Control of Reduced-Rating with A Battery Energy Storage


Performance improvement of Voltage infusion strategies for DVRs (Dynamic Voltage Restorers) and working modes are settled in this paper. Utilizing fuzzy logic control DVR with dc link& with Battery Energy Storage System frameworks are worked. Power quality issues for the most part consonant contortion, voltage swell and droop are diminished with DVR utilizing Synchronous Reference Theory (SRF hypothesis) with the assistance of fuzzificaton waveforms are watched.



 Fig.1.Block Diagram of DVR


Fig.2 Voltage waveforms at common coupling point (PCC) and load during harmonic distortion

Fig.3. the dc voltage injection from Battery energy Storage System connected DVR system at voltage swelling period

 Fig.4. DVR waveforms during voltage sag at time of voltage in phase injection

 Fig.5 Amplitude of load voltages and PCC voltages w.r.t time

 Fig 6.DVR waveforms during harmonic distortion at the time of voltage in phase injection


By applying distinctive voltage infusion conspires the job of DVR has been appeared with a most recent control strategy. The introduction of DVR has been offset with different plans with a decreased rating VSC. For gaining the power of DVR, the reference stack voltages have been resolved with the assistance of unit vectors, for which the blunder of voltage addition is diminished. By utilizing SRF hypothesis the reference DVR voltages have been resolved. At last, the outcome inferred are that the in stage voltage addition with PCC voltage diminishes the DVR rating and yet at its DC transport the vitality source is squandered. battery energy storage system. Performance Improvement of DVR by Control of Reduced-Rating with A Battery Energy Storage.