Power Quality Improvement Using DVR in Power System

ABSTRACT

The dynamic voltage restorer (DVR) is one of the modern devices used in distribution systems to protect consumers against sudden changes in voltage amplitude. In this paper, emergency control in distribution systems is analysed by using the proposed multi functional DVR control strategy. Also, the multi loop controller using the Posicast and P+Resonant controllers is proposed in order to improve the transient response and eliminate the steady-state error in DVR response, respectively. The proposed algorithm is applied to some disturbances in load voltage caused by induction motors starting, and a three-phase short circuit fault. Also, the capability of the proposed DVR has been tested to limit the downstream fault current. The current limitation will restore the point of common coupling (PCC) ( (the bus to which all feeders under study are connected) voltage and protect the DVR itself. The idea here is that the DVR acts as a virtual impedance with the main aim of protecting the pee voltage during downstream fault without any problem in real power injection into the DVR. Simulation results obtained using MATLAB software show the capability of the DVR to control the emergency conditions of the distribution systems.

KEYWORDS:

1.      DVR

2.      Power System

3.      PCC

4.      Resonant controllers

5.      Closed loop control.

SOFTWARE: MATLAB/SIMULINK

BLOCK  DIAGRAM:

 

Fig.1. Representation of DVR system Injection/booster transformer

EXPECTED SIMULATION RESULTS:

Fig.2. Simulation showing the sag in the closed loop system

Fig.3. Simulation showing the swell in closed loop system

Fig .4. Simulation showing the output after DVR is connected

Fig.5. Output for real and reactive power control

Fig.6. Waveform for the fault analysis

Fig.7. output of FFT analysis for input!

CONCLUSION

The main purpose of using DVR in industries is to maximize efficiency in production. We choose the proposed an improved progressive phase changing scheme of post fault voltage. For any fault situation of voltage sag this method is effective which is proved from the analysis and

MATLAB simulation results. We chose MATLAB programming because it is easy and can be easily fed in any microprocessor chip. The sag transients can be easily mitigated and pre fault voltage can be established. For real time applications, this may necessitate the application of the microcontroller/processor with fast speed. The analysis done in this paper is detection and compensation of the voltage sag with DVR active power injection.

                                                       

REFERENCES

[1]   J. A. Martinez and J. M. Arnedo, "Voltage sag studies in distribution networks- part T: System modeling," iEEE Trans. Power Del., vol. 21, no. 3, pp. 338-345, Jul. 2012.

[2]    S. S. Choi, B. H. Li, and D. M. Vilathgamuwa, "Dynamic voltage restoration with minimum energy injection," iEEE Trans. Power Syst., vol. 15, no. I, pp. 51-57, Feb. 2011.

[3]    C. Benachaiba and B. Ferdi, "Voltage quality improvement using DVR," Electt. Power Qual. Utilisation, Journal, vol. XIV, no. 1, 2010.

[4]   D. M. Vilathgamuwa, H. M. Wijekoon, and S. S. Choi, "A novel technique to compensate voltage sags in multiline distribution systemthe interline dynamic voltage restorer," iEEE Trans. ind. Electron., vol. 53, no. 5, pp. 1603-1611, Oct. 2012.

[5]   M. I. Marei, E. F. EI-Saadany, and M. M. A. Salama, "A new approach to control DVR based on symmetrical components estimation," iEEE Trans. Power Del., vol. 22, no. 4, pp. 2017-2024, Oct. 2012.

Sensorless Brushless DC Motor Drive Based on the Zero-Crossing Detection of Back Electromotive Force (EMF) From the Line Voltage

ABSTRACT:

This paper describes a position sensorless operation of permanent magnet brushless direct current (BLDC) motor. The position sensorless BLDC drive proposed, in this paper, is based on detection of back electromotive force (back EMF) zero crossing from the terminal voltages. The proposed method relies on a difference of line voltages measured at the terminals of the motor. It is shown, in the paper, that this difference of line voltages provides an amplified version of an appropriate back EMF at its zero crossings. The commutation signals are obtained without the motor neutral voltage. The effectiveness of the proposed method is demonstrated through simulation and experimental results.

KEYWORDS:

1.      Back electromotive force (EMF) detection

2.      Brushless dc (BLDC) motor

3.      Sensorless control

4.      Zero crossing.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of the experimental setup

EXPECTED SIMULATION RESULTS:

Fig. 2. Phase current and speed waveform on no-load (experimental).

Fig. 3. Phase current and speed waveform on load (experimental).

Fig. 4. Phase current and speed waveform during loading transient (experimental).

Fig. 5. Phase current, virtual Hall, and real Hall sensor signal for 50% duty ratio PWM switching.

CONCLUSION

A simple technique to detect back EMF zero crossings for a BLDC motor using the line voltages is proposed. It is shown that the method provides an amplified version of the back EMF. Only three motor terminal voltages need to be measured thus eliminating the need for motor neutral voltage. Running the machine in sensorless mode is then proposed, in this paper, making use of the novel zero-crossing detection algorithm. While starting relies on triggering devices at the zero crossings detected using the proposed algorithm, continuous running is achieved by realizing the correct commutation instants 30◦ delay from the zero crossings. The motor is found to start smoothly and run sensorless even with load and load transients. Simulation and experimental results are shown which validate the suitability of the proposed method.

REFERENCES

[1]   . K. Iizuka,H.Uzuhashi, M. Kano, T. Endo, andK.Mohri, “Microcomputer control for sensorless brushless motor,” IEEE Trans. Ind. Appl., vol. IA- 21, no. 4, pp. 595–601, May/Jun. 1985.

[2]    J. Shao, D. Nolan,M. Teissier, and D. Swanson, “A novelmicrocontrollerbased sensorless brushless DC (BLDC) motor drive for automotive fuel pumps,” IEEE Trans. Ind. Appl., vol. 39, no. 6, pp. 1734–1740, Nov./Dec. 2003.

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

[4]   S. Ogasawara and H. Akagi, “An approach to position sensorless drive for brushlessDCmotors,” IEEE Trans. Ind. Appl., vol. 27, no. 5, pp. 928–933, Sep./Oct. 1991.

[5]   R. C. Becerra, T. M. Jahns, and M. Ehsani, “Four-quadrant sensorless brushless ECM drive,” in Proc. IEEE APEC, Mar. 1991, pp. 202–209.

Modeling and Control of Hybrid Power Filter using p-q Theory

 ABSTRACT:

The paper presents design of hybrid active power filter (HAPF) in a three-phase three-wire power system. Design is implemented with instantaneous reactive power theory for control of HAPF in order to mitigate harmonics generated by both non-linear and unbalanced load at the point of common coupling (peC). The p-q Theory enables the source current to be decomposed in αβ0 frame to obtain compensation current for each phase. The hysteresis band current controller is used to generate gating pulses for voltage source inverter (VSI). Over all harmonic reduction is achieved via the proposed control of HAPF and the THD levels are per the IEEE-519 standard. Investigation of proposed scheme is validated by extensive simulations using MATLAB / Simulink Sim-Power System tool box.

KEYWORDS:

1.      Harmonics

2.      Passive Filter

3.      Active Filter

4.      Hybrid Filter

5.      Power Quality

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1: Basic Diagram of SAF

EXPECTED SIMULATION RESULTS:

Fig. 2: Source Current THD (29.9%) without Filter

Fig. 3: Source Current THD (10. I 5%) using Passive Filter

Fig. 4: Source Current THD (4.47%) using Active Filter

Fig. 5: Source Current THD (2.02%) using HAPF

Fig. 6: Compensating Current for Phase a,b and c

Fig. 7: Load Current THD (10.39%) in HAPF

CONCLUSION

This paper highlights the efficacy of HAPF for improving the power quality by eliminating harmonics from power system. The HAPF with a constant power compensation control strategy and hysteresis-band current controller is proposed. A thorough simulation based investigation validates the competency of HAPF among all filters for harmonic mitigation in power system due to current quality problem. The performance examined has demonstrated the efficiency by reducing the source current THD for non-linear load. The THD is well below the specified limit ofIEEE-519 standard.

REFERENCES

[1] A. Baitha and N. Gupta, " A comparative analysis of passive filters for power quality improvement", Int. Conf on Advancements in Power and Energy (TAP Energy), pp. 327-332, 20 IS .

[2] B. Singh and V. Verma, "An improved hybrid filter for compensation of current and voltage harmonics for varying rectifier loads". Int. J. Electrical Power & Energy Systems, Vol. 29, No. 4, pp. 312-xxx, May 2007.

[3] H. Fujita, T. Yamasaki, and H. Akagi, " A hybrid active filters for damping of harmonic resonance in industrial power system," IEEE Trans. on Power Electrics, Vol IS , No. 2, pp. 209-216, 2000.

[4] F.Z. Peng, H. Akagi, and A. Nanbe, " A new approach to harmonic compensation in power systems-A combined system of shunt passive and series active filters," I EEE Trans. on Ind. Appt, Vol. 26, pp. 983-990, Nov. 1990

[5] B. Singh and V. Verma, "Design and Implementation of a Current Controlled Parallel Hybrid Power Filter" Int. Conf on Power Electronics, Drives and Energy Systems, PEDES'06, pp. 1-7, 2006.

Simulation of Power Active Filter using Instantaneous Reactive Power Theory

ABSTRACT:

The paper presents the structure of an active parallel filter for reducing harmonic pollution and reactive power. The active power filter control is based on instantaneous reactive power theory. The authors present the modelling of parallel active filter based on this theory and the simulation results in MATLAB-SIMULINK. The method is based on instantaneous reactive power (TPRI_P).

KEYWORDS:

1.        Distorting regime

2.        Harmonic pollution

3.        Power active filter

4.        Reactive power

5.        Simulation.

SOFTWARE: MATLAB/SIMULINK

BLOCK  DIAGRAM:

Figure 1. Parallel active filter

EXPECTED SIMULATION RESULTS:

Figure 2. The unfiltered current and the current filtered on phase “a”

Figure 3. The active and reactive powers

Figure 4. Current harmonics with three-phase load

Figure 5. Current harmonics with both loads

CONCLUSION

We considered three-phase system with the balanced voltages and presented the conventional method for determining the current value based on the instantaneous active power which was called TPRI_P. The control is made in the system of axes α - β, which use direct and inverse transformation to obtain the equations from one system to another coordinate axes. The currents obtained in the α-β are related to the alternating current power on the network to obtain the compensation current based on current knowledge of the load, in contrast to the conventional method (TPRI_Q) to obtain the controlled values of currents directly. As can be seen in calculations involved only active powers, perfectly measurable.

Also is observed that:

• It produces an increase of the current THD network in the case of the system constant   

   instantaneous power of the energy source.

• Is observed a small fluctuation by active power and reactive power of network in the system

  constant instantaneous power of the energy source.

• Regarding the homopolar power, network evolution is similar in both cases.

REFERENCES

[1]   * * Software Matlab 6.5.

[2]  Arad, S., Popescu, F. G., Pană, L. Improving the energetic efficiency at electric drives compressors of E.M. Lonea. Papers SGEM2013/Conference Proceedings, Vol. Energy and clean technologies, Albena Co., Bulgaria , 2013, 153 - 160.

[3]   Akagi H., Kanazawa Y., Nabae A., Instantaneous reactive power compensators comprising switching devices without energy storage components, IEEE Transactions on Industry Applications, Vol. IA-20, No. 1, May/June 1984, 625-630.

[4]   Akagi H., Kim H., The theory of instantaneous power in three-phase four-wire systems: A comprehensive approach, Conf. Rec. IEEE-IAS Annu. Meeting, 1999, 431-439.

[5]   Popescu, F.G., Arad, S, Marcu, M., Pana, L. Reducing energy consumption by modernizing drives of high capacity equipment used to extract lignite, Papers SGEM2013/Conference Proceedings, Vol.[1]Energy and clean technologies, Albena Co., Bulgaria , 2013, 183 - 190

Impact of Distributed Power Flow Controller to Improve Power Quality Based on Synchronous Reference Frame Method

ABSTRACT

Modern power utilities have to respond to a number of challenges such as growth of electricity demand specially in non-linear loads in power grids, consequently, some policies about the power with a higher quality should be considered. In this paper, distributed power flow controller (DPFC) which is similar to unified power flow controller (UPFC) in structure, is used to mitigate the voltage sag and swell as a power quality issue. Unlike UPFC, the common dc-link in DPFC, between the shunt and series converters is eliminated and three-phase series converter is divided to several single-phase series distributed converters through the transmission line. Also to detect the voltage sags and determine the three single-phase reference voltages of DPFC, the synchronous reference frame method is proposed. Application of DPFC in power quality enhancement is simulated in Matlab/Simulink environment which show the effectiveness of the proposed structure.

KEYWORDS:

1.      FACTS

2.      Power quality

3.      Sag and swell mitigation

4.      Distributed power flow controller.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. The DPFC structure.

Fig. 2. Active power exchange between DPFC converters.

EXPECTED SIMULATION RESULTS:

Fig. 3. Three-phase load voltage sag waveform.

Fig. 4. Mitigation of three-phase load voltage sag with DPFC.

Fig. 5. Three-phase load current swell waveform.

Fig. 6. Mitigation of load current swell with DPFC.

CONCLUSION

The power quality enhancement of the power transmission systems is an vital issue in power industry. In this study, the application of DPFC as a new FACTS device, in the voltage sag and swell mitigation of a system composed of a three-phase source connected to a non-linear load through the parallel transmission lines is simulated in Matlab/Simulink environment. The voltage dip is analyzed by implementing a three-phase fault close to the system load. To detect the voltage sags and determine the three single phase reference voltages of DPFC, the SRF method is used as a detection and determination method. The obtained simulation results show the effectiveness of DPFC in power quality enhancement, especially in sag and swell mitigation.

REFERENCES

[1] J. Faiz, G. H. Shahgholian, and M. Torabian, “Design and simulation of UPFC for enhancement of power quality in transmission lines,” IEEE International Conference on Power System Technology, vol. 24, no. 4, 2010.

[2] A. E. Emanuel and J. A. McNeill, “Electric power quality,” Annu. Rev. Energy Environ, 1997.

[3] I. N. R. Patne and K. L. Thakre “Factor affecting characteristics of voltage sag due to fault in the power system,” Serbian Journal of Electrical engineering. vol. 5, no.1, 2008.

[4] J. R. Enslin, “Unified approach to power quality mitigation,” in Proc. IEEE Int. Symp. Industrial Electronics (ISIE ’98), vol. 1, 1998.

[5] B. Singh, K. Al-Haddad, and A. Chandra, “A review of active filters for power quality improvement,” IEEE Trans. Ind. Electron. vol. 46, no. 5, pp. 960–971, 1999.

[6] M. A. Hannan and A. Mohamed, member IEEE, “PSCAD/EMTDC simulation of unified series-shunt compensator for power quality improvement,” IEEE Transactions on Power Delivery, vol. 20, no. 2, 2005.