A New PWM and Commutation Scheme for One Phase Loss Operation of Three- Phase Isolated Buck Matrix-Type Rectifier

ABSTRACT:

In this paper, a new PWM scheme and commutation method is presented for one phase loss operation of three-phase isolated buck matrix-type rectifier. With the proposed PWM scheme, the maximum allowable voltage gain for one phase loss operation can be achieved, which permits the continuous operation of the converter to deliver 2/3 of rated power and regulate the output voltage with maximum output voltage drop less than 5% of nominal output voltage. In addition, with the proposed commutation method, a safe transition from one phase loss operation to normal operation and vice versa can occur with minimum commutation steps (two-step) under zero voltage switching (ZVS) condition. The performance of the proposed PWM scheme and commutation schemes with one phase loss operation is evaluated and verified by simulations and experiments on a 5kW prototype.

KEYWORDS:

1.      PWM

2.      Commutation

3.      Matrix converter

4.      Three phase

5.      One phase loss

6.      Isolated

7.      Buck rectifier

8.      ZVS

9.      MOSFET

10.  High frequency

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. ZVS three-phase PWM rectifier.

EXPECTED SIMULATION RESULTS:

Fig. 2. Simulated waveforms for 2/3PO_max, vLL = 480V and ma = 0.75 when “phase C” is shorted at t1 and recovered at t2: (a) input phase voltages, (b) input phase currents, (c) transformer secondary voltage, (d) output of bridge rectifier, (e) output voltage and battery set point, (f) output inductor current.

CONCLUSION:

In this paper, operation of the three-phase isolated Buck matrix-type rectifier under one phase loss condition is described and a new PWM scheme and commutation method for the one phase loss operation is proposed. With the proposed switching scheme and commutation method, two step commutation with ZVS (here either using ZVS or zero voltage turn-ON) can be realized for one phase loss operation and also for the transition from normal operation to one phase loss operation and from one phase loss operation to normal operation. Operation and performance of the converter with the proposed PWM and commutation method are verified with simulation and experimental results. Based on the experimental results obtained from a 5 Kw prototype, it is shown that the converter is able to deliver 2/3 of maximum output power to the load and regulate the output voltage with maximum voltage drop less than 5% of nominal output voltage. Current stress of the converter and input current THD and spectrum analysis are also provided in the experimental results with one phase loss operation. The relatively large THD (around 40%) is one of the drawbacks for this converter when operating under one phase loss condition.

REFERENCES:

[1] S. Manias and P. D. Ziogas, “A Novel Sinewave in AC to DC Converter with High-Frequency Transformer Isolation”, IEEE Trans. Industrial Electronics, vol. IE-32, no. 4, pp. 430-438, Nov., 1985.

[2] K. Inagaki, T. Furuhashi, A. Ishiguro, M. Ishida, and S. Okuma, “A New PWM Control Method for ac to dc Converters with High- Frequency Transformer Isolation”, IEEE Trans. Industry Applications, Vol. 29, No. 3, pp. 486-492, May/Jun., 1993.

[3] V. Vlatković and D. Borojević “Digital-Signal-Processor-Based Control of Three- Phase Space Vector Modulated Converters”, IEEE Trans. Industrial Electronics, vol. 41, no. 3, pp. 326-336, Jun., 1994.

[4] V. Vlatković and D. Borojević, and F. C. Lee, “A Zero-Voltage Switched, Three-phase Isolated PWM Buck Rectifier”, IEEE Trans. Power Electronics, vol. 10, No. 2, pp. 148-157, Mar., 1995.

[5] R. García-Gil, J. M. Espí, E. J. Dede, and E. Sanchis-Kilders, “A Bidirectional and Isolated Three-Phase Rectifier With Soft-Switching Operation,” IEEE Trans. Industrial Electronics, vol. 52, no. 3, pp. 765-773, Jun, 2005.

MATLAB-Simulink Model Based Shunt Active Power Filter Using Fuzzy Logic Controller to Minimize the Harmonics

 ABSTRACT:

 The problem of quality electrical energy provided to the users has arisen. This is due to the increasing presence in network of nonlinear loads.They constitute a harmonic pollution source of the network, which generate many disturbances, and disturb the optimal operation of electrical equipments. This work, proposed a solution to eliminate the harmonics introduced by the nonlinear loads. It presents the analysis and simulation using Matlab Simulink of a active power filter (APF) compensating the harmonics and reactive power created by nonlinear loads in steady and in transients. The usefulness of the simulation approach to APF is demonstrated , have a better power quality insight using Matlab Simulink in order to develop new fuzzy logic controller based active power filter.

KEYWORDS:

1.      Active Power Filters

2.      Harmonics

3.      Fuzzy Logic Controller

4.      MATLAB

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1 Block diagram of Basic Active Power Filter

EXPECTED SIMULATION RESULTS:

Fig. 2 Three phase voltage and current waveform with non linear load

Fig.3 THD analysis of three phase voltage waveform with nonlinear load

Fig.4 Three phase voltages and current waveform with shunt active power filter with connected fuzzy logic controller

Fig.5 THD analysis of voltages with shunt active power filter using fuzzy logic controller

CONCLUSION:

The paper presents the application of the fuzzy logic controller to control the compensating voltage. The Mamdani max-min approach is used for the fuzzy inference and the defuzzification method, respectively. The design of input and output membership for the fuzzy logic controller is very important for the system performance. The simulation results show that the fuzzy logic controller provides a good performance to control the compensating voltage of shunt active power filter. The %THD of the voltages at PCC point can be followed the IEEE Std. 519-1992.

REFERENCES:

[1] I. J. Pitel, S. N. Talukdar, and P. Wood, “Characterization of Programmed-Waveform Pulse-Width Modulation,” IEEE Transactions on Industry Applications, Vol. IA-16, Sept./Oct. 1980, pp. 707–715.

[2] Wilson E. Kazibwe and Mucoke H. Senduala : “Electric Power Quality Control Techniques”. New York: Van Nostrand Reinhold, 1993

[3] N. Mohan, “A Novel Approach to Minimize Line- Current Harmonics in Interfacing Power Electronics Equipment with 3-Phase Utility Systems”, IEEE Trans on Power Delivery, Vol. 8, July. 1993, pp 1395-1401.

[4] Elias M. Stein, Timonthy S. Murphy : “Harmonic Analysis: Real-Variable Methods, Orthogonality and Oscillatory Integrals.”, Princeton, N.J.: Princeton University Press, 1993

[5] J.S. Lai and T.S. Key, “Effectiveness of harmonic mitigation equipment for commercial office buildings,” IEEE Transactions on Industry Applications, vol.33, no.4, sep 1997, pp. 1065-1110

Simulation Analysis of DVR Performance for Voltage Sag Mitigation

ABSTRACT:

Voltage sag is literally one of power quality problem and it become severe to industrial customers. Voltage sag can cause miss operation to several sensitive electronic equipments. That problem can be mitigating with voltage injection method using custom power device, Dynamic Voltage Restorer (DVR). This paper presents modeling and analysis of a DVR with pulse width modulation (PWM) based controller using Matlab/Simulink. The performance of the DVR depends on the efficiency of the control technique involved in switching the inverter. This paper proposed two control techniques which is PI Controller (PI) and Fuzzy Logic Controller (FL). Comprehensive results are presented to assess the performance of each controller as the best power quality solution. Other factors that also can affect the performance and capability of DVR are presented as well.

KEYWORDS:

1.      Voltage sag

2.      Dynamic Voltage Restore

3.      Pulse Width Modulation (PWM)

4.      PI Controller

5.      Fuzzy Logic Controller

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Figure1. DVR Modelling using Matlab/Simulink

 EXPECTED SIMULATION RESULTS:

Figure 2. (a) Injection voltage from DVR controlled by PI ; (b) injection voltage controlled by FL

Figure 3. (a) Output voltage at load 1 after injection voltage from DVR controlled by PI; (b) Output voltage at load 1after injection voltage controlled by FL.

Figure 4. (a) Injection voltage from DVR controlled by PI; (b) injection voltage controlled by FL.

Figure 5. (a) Output voltage at load 1 after injection voltage from DVR controlled by PI; (b) Output voltage at load 1after injection voltage controlled by FL.

Figure 6. THD generated when PI controller is applied

Figure 7. THD generated when FL controller is applied.

CONCLUSION:

In this study, the modeling and simulation of DVR controlled by PI and FL Controller has been developed using Matlab/Simulink. For both controller, the simulation result shows that the DVR compensates the sag quickly (70μs) and provides excellent voltage regulation. DVR handles all types, balanced and unbalanced fault without any difficulties and injects the appropriate voltage component to correct any fault situation occurred in the supply voltage to keep the load voltage balanced and constant at the nominal value. Both controllers show an excellent performance and generate low THD (<5%). However, it can be seen that FL Controller gives better performance with THD generated with only 0.64% whilst PI generated 1.68% THD. However, other several factors that can affect the performance of DVR need to be addressed for enhancement of the output voltage. These factors are the energy storage capacity and transformer rating. From the simulation, it clearly shows the importance of these two factors and how they affect the performance of DVR. Therefore, when it comes to implementation, it is crucial to consider these factors, so that the performance of DVR is optimized.

REFERENCES:

[1] Omar, R. Rahim, N.A. “New Control Technique Applied in Dynamic Voltage Restorer for Voltage Sag Mitigation” Industrial Electronics and Applications, 2009. ICIEA 2009. 4th IEEE Conference on.

[2] Faisal, M.F. “Power Quality Management Program: TNB’s Experience”, Distribution Engineering, TNB 2005.

[3] Wahab, S.W. Yusof, A.M. “Voltage Sag Mitigation Using Dynamic Voltage Restorer (DVR) System, ELEKTRIKA, 8(2),2006, 32-37.

[4] IEEE Standard Board (1995), “IEEE Std. 1159-1995”, IEEE  Recommended Practice for Monitoring Electric Power Quality”. IEEE Inc. New York.

[5] Kim H. “Minimal Energy Control for a Dynamic Voltage Restorer”, In proceedings of the Power Conversion Conference, Osaka, Japan, 2002, pp. 428-433.

Photovoltaic Based Dynamic Voltage Restorer with Energy Conservation Capability using Fuzzy Logic Controller

ABSTRACT:

In this paper, a Photovoltaic based Dynamic Voltage Restorer (PV-DVR) is proposed to handle deep voltage sags, swells and outages on a low voltage single phase residential distribution system. It can recover sags up to 10%, swells up to 190% of its nominal value. Otherwise, it will operate as an Uninterruptable Power Supply (UPS) when the utility grid fails to supply. It is also designed to reduce the usage of utility power, which is generated from nuclear and thermal power stations. A series injection transformer is connected in series with the load when restoring voltage sag and swell and it is reconfigured into parallel connection using semiconductor switches when it is operating in UPS and power saver mode. The use of high step up dc-dc converter with high-voltage gain reduces the size and required power rating of the series injection transformer. It also improves the stability of the system. The Fuzzy Logic (FL)  controller with two inputs maintains the load voltage by detecting  the voltage variations through d-q transformation technique.  Simulation results have proved the ability of the proposed DVR  in mitigating the voltage sag, swell and outage in a low voltage single phase residential distribution system.

KEYWORDS:

1.      Dynamic Voltage Restorer

2.      Photovoltaic

3.      Voltage Sag

4.      Voltage Swell

5.      Outages

6.      High Step up dc-dc Converter

7.      Fuzzy Logic Controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Structural block diagram of the proposed system.

EXPECTED SIMULATION RESULTS:

(a)     Supply Voltage

(b)     Injected Voltage

(c)     Load Voltage

(d)     Load Current

(e) Load voltage THD

Fig. 2. Supply voltage, Injected voltage, Load voltage, Load Current and

Fig. 3. Load Voltage with PI controller

(a)     PV array output voltage without low power boost converter

(b) PV array output voltage with low power boost converter

Fig. 4. PV array output voltage without and with boost converter

Fig. 5. Output voltage of the high step up DC-DC converter

CONCLUSION:

This paper proposed a new PV based DVR to reduce the energy consumption from the utility grid. The design of a Dynamic Voltage Restorer (DVR) which incorporates a PV array module with low and high power boost converters as a DC voltage source to mitigate voltage sags, swells and outages in low voltage single phase distribution systems using FL controller has been presented. The modeling and simulation of the proposed PV based DVR using MATLAB simulink has been presented. The FL controller utilizes the error signal from the comparator to trigger the switches of an inverter using a sinusoidal PWM scheme. The proposed DVR utilizes the energy drawn from the PV array and the utility source to charge the battries during normal operation. The stored energies in battery are converted to an adjustable single phase ac voltage for mitigation of voltage sag, swell and outage. The simulation result shows that the PV based DVR with FL controller gives better dynamic performance in mitigating the voltage variations. The proposed DVR is operated in:

Standby Mode: when the PV array voltage is zero and the inverter is not active in the circuit to keep the voltage to its nominal value.

Active Mode: when the DVR senses the sag, swell and outage. DVR reacts fast to inject the required single phase compensation voltages.

Bypass Mode: when DVR is disconnected and bypassed in case of maintenance and repair.

Power Saver mode: when the PV array with low step-up dc-dc converter output power is enough to handle the load.

Further work will include a comparison with laboratory experiments on a low voltage DVR in order to compare simulation and experimental results. The multiple functions of DVR require further investigation.

REFERENCES:

[1] H.Ezoji, A.Sheikholeslami, M.Tabasi, and M.M.Saeednia, “Simulation of dynamic voltage restorer using hysteresis voltage control,” European journal of scientific research, vol. 27, pp. 152-166, Feb 2009.

[2] F.A.L.Jowder, “Modeling and simulation of different system topologies for dynamic voltage restorer using simulink,” in proc. EPECS ’09, 2009, p. 1-6.

[3] R.Strzelecki, and G.Benysek, “Control strategies and comparison of the dynamic voltage restorer,” in proc. PQ ‘08, 2008, p. 79-82.

[4] P.Boonchiam, and N.Mithulananthan, “Understanding of dynamic voltage restorers through MATLAB simulation,” Thammasat Int. J. Sc. Tech., Vol. 11, No.3, pp. 1-6, Sep 2006.

[5] K.C.Bayinder, A.Teke, and M.Tumay, “A Robust control of dynamic voltage restorer using fuzzy logic,” in proc. ACEMP ’07, 2007, p.55