Three-Phase For-Wire Shunt Active Filter With Unbalanced loads

 

ABSTRACT:

The electrical power quality at low voltage alternative networks became a serious concern because of the increased use of nonlinearloads and pollutants. This work is to improve the quality of electric current in such networks. Four-Wire Shunt Active Filter is studied; deferent loads (balanced and unbalanced) are discussed. We propose to identify harmonic and reactive currents at the base of Self-Tuning-Filters, which proved very good filtering performance, either in transient or steady state. The simulations demonstrate the importance of this work in harmonic filtering and reactive power compensation.

KEYWORDS:

  1. Shunt Active Filter (SAF)
  2. Total Harmonic Distortion(THD)
  3. Self-Tuning-Filter (STF)
  4. Unbalanced loads

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 Fig. 1. Block diagram of the APF

EXPECTED SIMULATION RESULTS:

 

 Fig.2 Simulation results of STFs under three balanced loads:

(a) Supply and loads currents, (b) 1st phase filter current, (c) Neutral currents,

(d) Harmonic current spectre of 1st phase load, (e) Harmonic current spectre of 1st phase of supply

 

 Fig.3 Simulation results under three unbalanced loads:

(a) Source and loads currents, (b) Neutral currents, (c) Filter currents,(d) Harmonic currentspectres of loads,(e) Harmonic current spectres of supply

                          

Fig.4 Supply voltage and current (phase 1)

CONCLUSION:

In this paper we have presented a new tree-phase for-wire active power filter based on STF extraction, to identifyharmonic current and reactive power. The objective was to improve the dynamic of identification method and also selectivity. The advantages of this filter are: STFs don’t introduce any displacement between input and output, at the fundamental pulsation. Good dynamic,and high selection of fundamental signal. Their selectivity is improved by reducing K. They can filtrate the voltages that are used to calculate instantaneous powers, to identify perturbation, and so PLL is not used. This method reduces the complexity of the control scheme and consequently facilitates the digital implementation of the control system. Those results demonstrate the good performances of the proposed control.

REFERENCES:

[l] M. Abdusalam, P. Poure,S. Saadate, “Hardware Implementation of a Three-PhaseActive Filter System with HarmonicIsolationBased on Self-Tuning-Filter”, IEEE. Power Electronics Specialists Conference, Aug. 2008, pp. 2276-2278.

[2] M. Abdusalam, P. Poure, S. Saadate, “A New Control Method of Hybrid Active Filter to Eliminate the 5th and 7th Harmonic Frequency Using Self-Tuning-Filter in the Feedforward Loop”. IREE, International Review of Electrical Engineering, Feb. 2008, pp. 65-72.

[3] A Ghamri, M.T Benchouia, A.Golea.,Sliding-mode Control Based Three-phase Shunt Active Power Filter: Simulation and Experimentation; Electric Power Components and Systems Journal, 2012, 40( 4): 383-398.

[4] M. Abdusalam, P. Poure, S. Saadate, “A New ControlScheme of Hybrid Active Filter Using Self-Tuning Filter”, POWERENG, International Conference on Power Engineering , Energy and Electrical Drives, Setubal Portugal,April. 2007, pp. 12-14.

[5] M.C. Benhabib, S. Saadate, “ New Control Approach for Four-Wire Active Power FilterBasedon the Use of Synchronous Reference Frame”,Elsevier B.V. Electric Power Systems Research 73,Nov. 2004, pp. 353–362. .

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

 

ABSTRACT:

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

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

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

 EXPECTED SIMULATION RESULTS:

 

Fig. 2 Voltage and the current waveforms

a Ideal grid voltage

b Non-ideal (distorted and unbalanced) grid voltage

c Load currents under the ideal grid voltage

d Load currents under the non-ideal grid voltage

 

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

a Under the ideal voltage

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

c Under the ideal voltage

d Under the non-ideal voltage

Fig. 4 Compensation of the grid current harmonics

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

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

c By using the proposed method under the ideal voltage

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

 CONCLUSION:

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

REFERENCES:

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

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

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

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

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

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

 

ABSTRACT:

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

KEYWORDS:

  1. Active filter
  2. Harmonics isolator
  3. Distorted voltage conditions
  4. Self-tuning filter
  5. Fuzzy logic control and PWM control

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig1.power system configuration

 EXPECTED SIMULATION RESULTS:

 

Fig. 2. Supply voltage Vs waveform

Fig. 3. Supply current Is waveform without filtering.

Fig. 4. Supply current Is waveform with filter.

Fig. 5. Active filter current If

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

Fig. 7. DC voltage of the condensers Vdc

CONCLUSION:

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

REFERENCES:

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

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

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

[4] O. Vodyakho, T. Kim, S. Kwak, ‘Three-level inverter based active power filter for the three-phase, four-wire system,” IEEE Power Electronics Specialists Conference, pp. 1874-1880,2008.

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

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

ABSTRACT:

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

KEYWORDS:

  1. Hybrid active power filters
  2. Self tuning filter
  3. Hystrsis current control
  4. Matlab/Simulink

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 

Fig.1 Parallel hybrid active filter configuration

 EXPECTED SIMULATION RESULTS:

 

 

Fig.2 simulation Results

CONCLUSION:

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

REFERENCES:

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

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

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

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

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

 

The Benefit of Harmonics Current Using a New Topology of Hybrid Active Power Filter

 

ABSTRACT:

 This paper presents a new idea to benefit of eliminated harmonics current by using a new topology of hybrid active power filter (HAPF) to compensate harmonics current to be sinusoidal in order to feed some loads. The design and simulation of a new three phase HAPF circuit using a shunt active power filter (APF) connected in parallel with a capacitor (C) line of a (LC) low pass filter (LPF) has been submitted.

The first aim of the new circuit is to use the LPF as a path to pass the fundamental frequency (50 Hz) current and eliminate other high order frequencies, while APF compensates high order frequencies and compensate reactive power of the circuit. The second aim is to benefit from the modified wave in the high frequency branch of LPF to use it as a useful power in order to feed different loads. In addition, With this topology, the resonance problem (which usually happens between LPF and the system) will disappear because of using of APF in the high frequency branch.

The control circuit has been designed based on the instantaneous reactive power theory. A Clarke transformation equations and hysteresis current controller have been used in the HAPF’s design. The proposed circuit has provided a good harmonic elimination, total harmonic distortion (THD) reduced, reactive power compensation and a reasonable sinusoidal waveform.

KEYWORDS:

  1. Harmonics Elimination
  2. Hybrid Active Power Filter
  3. Active Power Filter
  4. Passive Filters
  5. Total Harmonic Distortion

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. New proposed HAPF

 EXPECTED SIMULATION RESULTS:

 

Fig. 2. C-branch’s current before adding APF

Fig. 3. Source current before filtering

Fig. 4. Source current after filtering

Fig. 5. The current of resistive load after filtering

 CONCLUSION:

This paper has presents a new topology of three phase HAPF. The system has been designed, tested and simulated by Matlab- Simulink program in three steps; firstly, without using filters, secondly, with LC low pass filter, finally, using LPF in combine with APF which represent HAPF. After a comparison between the values of total harmonic distortion (THD%) in three aforementioned circuits, the results of the simulation confirmed the effectiveness of the proposed HAPF because of the big decreasing in the THD value and high rate elimination of the harmonics. The proposed HAPF offers a reactive power compensation for the circuit because of using shunt APF. Consequently, the power quality of the circuit will improve. This paper has submit a new idea to benefit of eliminated harmonic current in the C-branch of LPF through using APF in shunt with C-branch of LPF and compensate high frequency currents in order to use it as a power supply to feed different loads. In this research, a resistive load has been presented as an invested load. However, in practical life lighting bulbs can be used as loads.

REFERENCES:

[1] C. Francisco, Harmonics and power systems. CRC press, 2006.

[2] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, “A review of three-phase improved power quality ac-dc converters,” Industrial Electronics, IEEE Transactions on, vol. 51, no. 3, pp. 641–660, 2004.

[3] L. Gyugyi and E. C. Strycula, “Active ac power filters,” in Proc. IEEE/IAS Annu. Meeting, vol. 19, 1976, pp. 529–535.

[4] L. Czarnecki, “An overview of methods of harmonic suppression in distribution systems,” in Power Engineering Society Summer Meeting, 2000. IEEE, vol. 2, 2000, pp. 800–805.

[5] A. Nassif, W. Xu, and W. Freitas, “An investigation on the selection of filter topologies for passive filter applications,” Power Delivery, IEEE Transactions on, vol. 24, no. 3, pp. 1710–1718, July 2009.

Novel Approach Employing Buck-Boost Converter as DC-Link Modulator and Inverter as AC-Chopper for Induction Motor Drive Applications: An Alternative to Conventional AC-DC-AC Scheme

 

ABSTRACT:

Induction motor (IM) is the workhorse of the industries. Amongst various speed control schemes for IM, variable-voltage variable-frequency (VVVF) is popularly used. Inverters are broadly used to produce variable/controlled frequency and variable/controlled output voltage for various applications like ac machine drives, switched mode power supply (SMPS), uninterruptible power supplies (UPS), etc. This paper presents the two-fold solution of control for such loads. In this novel solution, rms values of output voltage is varied by controlling the inverter duty ratio which operates as an ac chopper, while the fundamental frequency of output voltage is varied by controlling the buck-boost converter according to the reference frequency given to it. The buck-boost converter shuffles between buck-mode and boost-mode to produce required frequency by generating the modulated dc-link for the inverter, unlike conventional fixed dc-link in case of ac-dc-ac converters. The proposed technique eliminates over modulation (as in conventional pulse width modulated inverters) and hence the non-linearity, and lower order harmonics are absent. Further, it reduces dv/dt in the output voltage resulting less stress on the insulation of machine winding, and electromagnetic interference. However, the proposed scheme demands more number of power semiconductor devices as compared to their conventional ac-dc ac counterparts. Simulation studies of proposed single-phase as well as three-phase topologies are carried out in MATLAB/Simulink. Hardware implementation of proposed single-phase topology is done using dSPACE DS1104 R&D controller board and results are presented.

KEYWORDS:

  1. Ac-chopper
  2. Buck-boost converter
  3. Dc-link modulation
  4. Inverter
  5. Variable-voltage variable-frequency
  6. V/f  induction motor drive

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram for the proposed topology.

EXPECTED SIMULATION RESULTS:

 

 (a) Plot of output voltage (rms) of inverter v/s duty ratio.

 

(b) Output voltage waveform of the proposed inverter: [X-axis: 1 div. = 0.01 s, Y-axis: 1 div. = 100 V].

(c) Output voltage of conventional inverter for unipolar SPWM: [X-axis: 1 div. = 0.01 s, Y-axis: 1 div. = 100 V].

(d) FFT plot of the output voltage with the proposed topology.

(e) FFT plot of output voltage with unipolar SPWM inverter.

Fig. 2. Analysis of the proposed topology.

 

(a) Output voltage of the proposed topology: [X-axis: 1 div. = 0.01 s, Y-axis:

1 div. = 50 V].

(b) Comparison of reference voltage and input voltage (upper trace), comparison of reference voltage and output voltage (lower trace) of buck-boost converter Upper trace: [X-axis: 1 div. = 0.01 s, Y-axis: 1 div. = 100 V] Lower trace: [X-axis: 1 div. = 0.01 s, Y-axis: 1 div. = 50 V].

(c) Output voltage and reference voltage of buck-boost converter at f=10 Hz,

f=20 Hz, f=25 Hz: [X-axis: 1 div. = 0.01 s, Y-axis: 1 div. = 100 V].

(d) Output voltage and reference voltage of buck-boost converter at f=30 Hz,

f=40 Hz, f=50 Hz: [X-axis: 1 div. = 0.01 s, Y-axis: 1 div. = 100 V].

Fig. 3 Simulation results of the proposed buck-boost converter.

(b) Gate pulses of MOSFETs M2 and M3, Comparison of input voltage and reference voltage, Gate pulses M1, M2, M3: [X-axis: 1 div. = 0.002 s, Y-axis: 1 div. = 1 V], Voltage: [X-axis: 1 div. = 0.002 s, Y-axis: 1 div. = 100 V].

(c) Output voltage waveforms of buck-boost converter without La Output voltage of buck-boost converter and reference voltage with La: [X-axis: 1 div. = 0.02 s, Y-axis: 1 div. = 50 V], Output voltage of inverter with La: [Xaxis: 1 div. = 0.02 s, Y-axis: 1 div. = 100 V].

(d) Output voltage of buck-boost converter and inverter and inverter with La Blue color: Reference voltage, Green color: Actual output voltage of buckboost converter, Output voltage of buck-boost converter and reference voltage without La: [X-axis: 1 div. = 0.02 s, Y-axis: 1 div. = 50 V], Output voltage of inverter without La: [X-axis: 1 div. = 0.02 s, Y-axis: 1 div. = 100 V].

Fig. 4 Results for improving output voltage of inverter.

(b) Pole voltage of phase A and output of buck-boost converter compared with reference voltage of three-phase system Blue color: Reference voltage Green color: Actual output voltage of buck-boost converter for three-phase Pole voltage of phase A: [X-axis: 1 div. = 0.05 s, Y-axis: 1 div. = 50 V] Output voltage of buck-boost converter of phase A: [X-axis: 1 div. = 0.05 s,

Y-axis: 1 div. = 50 V].

Fig. 5 Simulation result of proposed three-phase topology.

CONCLUSION:

Relation between fundamental output voltage (rms) and duty ratio of switches of ac chopper operating as inverter is linear. So, on increasing the duty ratio of pulses given to switches, output voltage of inverter increases linearly. To get 100 % inverter output voltage, no need to go in over modulation region, which eliminates the non-linearity. The profile of output voltage of inverter (with chopping depending on the duty ratio of its switches) is sinusoidal because of modulated dc-link provided by the buck-boost converter, which reduces lower order harmonics, and %THD. It also reduces dv/dt as envelope of output voltage is sinusoidal as full dc-link voltage is not switched. This reduction in dv/dt reduces the stresses on the enameled copper wire of the stator winding of the motor. It will reduce the inter-turn short circuit failure of stator winding. Also this reduction of dv/dt will reduce the electromagnetic interference generated by the inverter in the drive system. In the proposed scheme, output voltage of buck-boost converter follows the reference voltage very closely for different frequencies, so when reference voltage is greater than input voltage, converter has to operate in boost mode else operates in buck mode. Hardware implementation of proposed single phase scheme is carried out. The hardware results have very close resemblance with the simulation results. The proposed concept is novel, and with appropriate refinements, can offer new era of control of inverter for V/f three-phase induction motor drive applications. However, it demands more number of power semiconductor devices compared to that needed for the conventional ac-dc-ac approach.

REFERENCES:

[1] Jose Thankachan, and Saly George, “A novel switching scheme for three phase PWM ac chopper fed induction motor,” in Proc. IEEE 5th India International Conference on Power Electronics (IICPE), pp. 1-4, 2012.

[2] Amudhavalli D., and Narendran L., “Speed control of an induction motor by V/f method using an improved Z-source inverter,” in Proc. International Conference on Emerging Trends in Electrical Engineering and Energy Management (ICETEEEM), pp. 436-440, 2012.

[3] G. W. Heumann, “Adjustable frequency control of high-speed induction motors,” Electrical Engineering, vol. 66, no. 6, pp. 576-579, June 1947. [4] Mineo Tsuji, Xiaodan Zhao, He Zhang, and Shinichi Hamasaki, “New simplified V/f control of induction motor for precise speed operation,” in Proc. International Conference on Electrical Machines and Systems (ICEMS), pp. 1-6 , 2011.

[5] V. K. Jayakrishnan, M. V. Sarin, K. Archana, and A. Chitra, “Performance analysis of MLI fed induction motor drive with IFOC speed control,” in Proc. Annual IEEE India Conference (INDICON), pp. 1-6, 2013.

Electric Spring for Voltage and Power Stability and Power Factor Correction

ABSTRACT:

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.

KEYWORDS:

  1. Demand Side Management
  2. Electric Spring
  3. Power Quality
  4. Single Phase Inverter
  5. Renewable Energy

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 

 Fig. 1. Electric Spring in a circuit

 EXPECTED SIMULATION RESULTS:

Fig. 2. Over-voltage, Conventional ES: RMS Line voltage, ES Voltage, and Non-Critical load voltage (ES turned on at t=0.5 sec)

Fig. 3. Over-voltage, Conventional ES: Power Factor of system (ES turned on at t = 0.5 sec)

Fig. 4. 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. 5. Under-voltage, Conventional ES: RMS Line voltage, ES Voltage, and Non-Critical load voltage (ES turned on at t=0.5 sec)

Fig. 6. Under-voltage, Conventional ES: Power Factor of system (ES turned on at t = 0.5 sec)

Fig. 7. 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.8. Over-voltage, Improvised ES: RMS Line voltage, ES Voltage, and Non-Critical load voltage (ES turned on at t=0.5 sec)

Fig. 9. Over-voltage, Improvised ES: Power Factor of system (ES turned on at t = 0.5 sec)

Fig. 10. Over-voltage, Improvised ES: Active and Reactive power across critical load, non-critical load, and electric spring (ES turned on at t=0.5 sec)

Fig. 11. Under-voltage, Improvised ES: RMS Line voltage, ES Voltage, and Non-Critical load voltage (ES turned on at t=0.5 sec)

Fig. 12. Under-voltage, Improvised ES: Power Factor of system (ES turned on at t = 0.5 sec)

Fig. 13. Under-voltage, Improvised ES: Active and Reactive power across critical load, non-critical load, and electric spring (ES turned on at t=0.5 sec)

CONCLUSION:

In this paper as well as earlier literatures, 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. 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 [1]. 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 insitu power factor correction in a renewable energy powered microgrids. It would be a unique demand side management (DSM) solution which could be implemented without any reliance on information and communication technologies.

REFERENCES:

[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: http://www.google.com/patents/US20120080420

[3] C. K. Lee, N. R. Chaudhuri, B. Chaudhuri, 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 2013.

[4] C. K. Lee, B. Chaudhuri, 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 2013.

[5] C. K. Lee, K. L. Cheng, and W. M. Ng, “Load characterisation of electric spring,” in 2013 IEEE Energy Conversion Congress and Exposition, Sept 2013, pp. 4665–4670.

 

 

DC Electric Springs A Technology for Stabilizing DC Power Distribution Systems

 

ABSTRACT:

There is a growing interest in using DC power systems and microgrids for our electricity transmission and distribution, particularly with the increasing penetration of photovoltaic power systems. This paper presents an electric active suspension technology known as the DC electric springs for voltage stabilization and power quality improvement. The basic operating modes and characteristic of a DC electric spring with different types of serially-connected non-critical loads will first be introduced. Then, the various power delivery issues of the DC power systems, namely bus voltage variation, voltage droop, system fault, and harmonics, are briefly described. The operating limits of a DC electric spring in a DC power grid is studied. It is demonstrated that the aforementioned issues can be mitigated using the proposed DC electric spring technology. Experiment results are provided to verify the feasibility of the proposed technology.

KEYWORDS:

  1. Smart load
  2. Distributed power systems
  3. Power electronics
  4. Electric springs
  5. DC grids
  6. Smart grid

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. The basic configuration of DC electric springs.

EXPECTED SIMULATION RESULTS:

Fig. 2. Enlarged experiment waveforms based on the raw data exported from the oscilloscope corresponding

Fig. 3. Enlarged experiment waveforms based on the raw data exported from the oscilloscope corresponding

CONCLUSION:

In this paper, the concept of DC electric springs (ES) is firstly introduced to cope with several issues of DC power grids. The DC-ES is proposed as an active suspension system. Similar to their AC counterparts, the DC-ES can provide dynamic voltage regulation for the DC bus. The DC-ES connected in series with different types of non-critical loads to form a smart load have been analyzed and their operating modes have been identified and explained. Furthermore, the operating limits of the DC-ES under a given set of system parameters is studied, which provides quantitative analytical procedures to estimate the theoretical limits of ES. The paper provides a fundamental study on the DC-ES including the characteristics, the modes of operation, and the operating limits. The theoretical analysis and the performance of the DCES have been practically verified.

REFERENCES:

[1] R. Lobenstein and C. Sulzberger, “Eyewitness to DC history,” Power and Energy Magazine, IEEE, vol. 6, no. 3, pp. 84–90, May 2008.

[2] G. Neidhofer, “Early three-phase power,” Power and Energy Magazine, IEEE, vol. 5, no. 5, pp. 88–100, Sep. 2007.

[3] B. C. Beaudreau, World Trade: A Network Approach. iUniverse, 2004.

[4] H. Kakigano, Y. Miura, and T. Ise, “Distribution voltage control for DC microgrids using fuzzy control and gain-scheduling technique,” IEEE Trans. Power Electron., vol. 28, no. 5, pp. 2246–2258, May 2013.

[5] P. Loh, D. Li, Y. K. Chai, and F. Blaabjerg, “Autonomous operation of hybrid microgrid with AC and DC subgrids,” IEEE Trans. Power Electron., vol. 28, no. 5, pp. 2214–2223, May 2013.

Adaptive Speed Control of Brushless DC (BLDC) Motor Based on Interval Type-2 Fuzzy Logic

 

ABSTRACT:

To precisely control the speed of BLDC motors at high speed and with very good performance, an accurate motor model is required. As a result, the controller design can play an important role in the effectiveness of the system. The classic controllers such as PID are widely used in the BLDC motor controllers, but they are not appropriate due to non-linear model of the BLDC motor. To enhance the performance and speed of response, many studies were taken to improve the adjusting methods of PID controller gains by using fuzzy logic. Use of fuzzy logic considering approximately interpretation of the observations and determination of the approximate commands, provides a good platform for designing intelligent robust controller. Nowadays type-2 fuzzy logic is used because of more ability to model and reduce uncertainty effects in rule-based fuzzy systems. In this paper, an interval type-2 fuzzy logic-based proportional-integral-derivative controller (IT2FLPIDC) is proposed for speed control of brushless DC (BLDC) motor. The proposed controller performance is compared with the conventional PID and type-1 fuzzy logic-based PID controllers, respectively in MATLAB/Simulink environment. Simulation results show the superior IT2FLPIDC performance than two other ones.

KEYWORDS:

  1. Brushless DC (BLDC) Motor
  2. Invertal Type-2 Fuzzy Logic
  3. Speed Control
  4. Self-tuning PID Controller

  SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1. Block Diagram of speed control of BLDC Motor

EXPECTED SIMULATION RESULTS:

Figure 2. Speed Deviation of BLDC Motor

Figure 3. Load Deviation of BLDC Motor

Figure 4. Torque Deviation of BLDC Motor

 CONCLUSION:

In this paper, the speed control of the BLDC motor is studied and simulated in MATLAB/Simulink. In order to overcome uncertainties and variant working condition, the adjustment of PID gains through fuzzy logic is proposed. In this study, three controller types are considered and compared: conventional PID, type-1 and type-2 fuzzy-based self-tuning PID controllers. The simulation results show that type-2 fuzzy PID controller has superior performance and response than two other ones.

REFERENCES:

[1] A. Sathyan, N. Milivojevic, Y. J. Lee, M. Krishnamurthy, and A. Emadi, “An FPGA-based novel digital PWM control scheme for BLDC motor drives,” IEEE Trans. Ind. Electron., vol. 56, no. 8, pp. 3040–3049,Aug. 2009.

[2] F. Rodriguez and A. Emadi, “A novel digital control technique for brushless DC motor drives,” IEEE Trans. Ind. Electron., vol. 54, no. 5, pp. 2365–2373, Oct. 2007.

[3] Y. Liu, Z. Q. Zhu, and D. HoweDirect Torque Control of Brushless DC Drives With Reduced Torque RippleIEEE Trans. Ind. Appl., vol. 41, no. 2, pp. 599-608, March/April 2005.

[4] T. S. Kim, S. C. Ahn, and D. S. Hyun , “A New Current Control Algorithm for Torque Ripple Reduction of BLDC Motors,” in IECON’01, 27th Conf. IEEE Ind. Electron Society,2001

[5] W. A. Salah, D. Ishak, K. J. Hammadi, “PWM Switching Strategy for Torque Ripple Minimization in BLDC MotorFEI STU, Journal of Electrical Engineering, vol. 62, no. 3, 2011, 141–146.

An Advanced Current Control Strategy for Three-Phase Shunt Active Power Filters

ABSTRACT:

This paper proposes an advanced control strategy to enhance performance of shunt active power filter (APF). The proposed control scheme requires only two current sensors at the supply side and does not need a harmonic detector. In order to make the supply currents sinusoidal, an effective harmonic compensation method is developed with the aid of a conventional proportional-integral (PI) and vector PI controllers. The absence of the harmonic detector not only simplifies the control scheme but also significantly improves the accuracy of the APF, since the control performance is no longer affected by the performance of the harmonic tracking process. Furthermore, the total cost to implement the proposed APF becomes lower, owing to the minimized current sensors and the use of a four-switch three-phase inverter. Despite the simplified hardware, the performance of the APF is improved significantly compared to the traditional control scheme, thanks to the effectiveness of the proposed compensation scheme. The proposed control scheme is theoretically analyzed, and a 1.5-kVA APF is built in the laboratory to validate the feasibility of the proposed control strategy.

KEYWORDS:

  1. Active power filters (APFs)
  2. Harmonic current compensation
  3. Power quality
  4. Resonant controller

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. Typical control scheme of a shunt APF.

Fig. 2. Structure of the proposed control scheme for three-phase shunt APF.

 EXPECTED SIMULATION RESULTS:

 

 Fig. 3. Steady-state performance with PI current controller under RL load.

Fig. 4. Steady-state performance with proposed control scheme under RL load.

Fig. 5. Dynamic responses of proposed control scheme under RL load variations: (a) load applied (b) load changed.

Fig. 6. Steady-state performance with proposed control scheme under RLC load.

Fig. 7. Dynamic responses of proposed control scheme under RLC load variations: (a) load applied (b) load changed.

Fig. 8. Steady-state performance of the proposed control scheme under distorted supply voltage condition with (a) RL load and (b) RLC load.

Fig. 9. Steady-state performances of the four-switch APF with (a) RL load and (b) RLC load.

 CONCLUSION:

 In this paper, an advanced control strategy for the three-phase shunt APF was proposed. The effectiveness of the proposed control strategy was verified through various experimental tests, where the proposed control strategy presented good steady-state performance with nonlinear RL and RLC loads as well as good dynamic response against load variations: the supply current is almost perfect sinusoidal and in-phase with the supply voltage even under the distorted voltage condition. The experimental results verified that the absence of a harmonic detector results in faster transient responses as well as assures notches free in steady-state performances of the supply current. Moreover, we also confirmed that the FSTPI can be used to implement the APF without any degradation in the APF performance. In all of the experiments, THD factor of the supply current was reduced to less than 2%, which completely comply with the IEEE-519 and IEC-61000-3-2 standards.

REFERENCES:

[1] Recommended Practice for Harmonic Control in Electric Power Systems, IEEE Std. 519-1992, 1992.

[2] Limits for Harmonic Current Emission, IEC 61000-3-2, 2001.

[3] H. Akagi, “New trends in active filters for power conditioning,” IEEE Trans. Ind. Appl., vol. 32, no. 2, pp. 1312–1332, Nov./Dec. 1996.

[4] F. Z. Peng, “Application issues of active power filters,” IEEE Ind. Appl. Mag., vol. 4, no. 5, pp. 21–30, Sep./Oct. 1998.

[5] H. Akagi, E. H. Watanabe, and M. Aredes, Instantaneous Power Theory and Applications to Power Conditioning, M. E. El-Hawari, Ed.New York: Wiley, 2007.