Modeling and Simulation of a Distribution STATCOM using Sirnulink’s Power System Blockset  

 

ABSTRACT

This paper presents a study on the modeling of a STAT-COM (Static Synchronous Compensator) used for reactive power compensation on a distribution network. The power circuits of the D-STATCOM and the distribution network are modeled by specific blocks from the Power System Blockset while the control system is modeled by Simulink blocks. Static and dynamic performance of a E3 Mvar D-STATCOM on a 25-kV network is evaluated. An “average modeling” approach is proposed to simplify the PWM inverter operation and to accelerate the simulation for control parameters adjusting purpose. Simulation performance obtained with both modeling approaches are presented and compared.

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

 

Fig. 1. The cascade H-bridge converter based DSTATCOM.

 EXPECTED SIMULATION RESULTS

Fig. 2 Waveforms illustrating the D-STATCOM dynamic performance.

Fig. 3 Voltage and current waveforms during the change from inductive to capacitive operation at t = 0.2 s.

Fig. 4 Comparison between responses of detailed and average models for a step change in the network internal voltage. 

CONCLUSION

A detailed model of a D-STATCOM has been developed for use in Simulink environment with the Power System Blockset. Models of both power circuit and control system have been implemented in the same Simulink diagram allowing smooth simulation. Two modeling approaches (device and average modeling) have been presented and applied to the case of a +3Mvar D-STATCOM connected to a 25-kV distribution network. The obtained simulation results have demonstrated the validity of the developed models. Average modeling allows a faster simulation which is well suited to controller tuning purposes.

REFERENCES

[1] K.K. Sen, “STATCOM: Theory, Modeling, Applications,” in IEEE PES 1999 Winter Meeting Proceedings, pp. 11 77- 1183.

[2] Flexible AC Transmission Systems (FACTS), edited by Y.H. Song and A.T. Johns, The Institution of Electrical Engineers, London, UK, 1999.

[3] K.V. Patil, et al., “Application of STATCOM for Damping Torsional Oscillations in Series Compensated AC Systems,” IEEE Trans. on Energy Conversion, Vol. 13, No. 3,Sept. 1998, pp.237-243.

[4] C.D. Schauder, H. Mehta, “Vector Analysis and Control of Advanced Static VAR Compensators,” IEE Proceedings- [SI Power System Blockset For Use with Sirnulink, User’s Guide, The MathWorks Inc., 2000. C, Vol. 140, NO. 4, July 1993, pp. 299-306.

Control of Cascaded H-Bridge Converter based DSTATCOM for High Power Applications

 

ABSTRACT

This paper presents the simulation studies on a Cascaded H-Bridge converter based Distribution Static Synchronous Compensator (DSTATCOM) for improving the power quality of a distribution system. Voltage source converter based DSTATCOM has been established as the most preferred solution for management of reactive power in distribution utilities and for improving voltage regulation, power factor and power quality in industries. For high power applications, cascaded H-Bridge converter is the most ideal choice compared to two-level inverter with series connected power devices. In the present work DSTATCOM controller is designed using DQO modelling for reactive power management and thereby improving the power factor in distribution systems. The dc link voltage and the three phase load currents are used as feedback signals for the controller and it is designed in such a way that DSTATCOM is able to supply the reactive current demanded by the load both during steady state and transient conditions using sinusoidal pulse width modulation control.

KEYWORDS

  1. Cascaded H-Bridge Converter
  2. DSTATCOM
  3. Reactive power compensation
  4. Sinusoidal PWM

 SOFTWARE: MATLAB/SIMULINK

SIMULINK BLOCK DIAGRAM:

Fig. 1. The cascade H-bridge converter based DSTATCOM.

 

EXPECTED SIMULATION RESULTS

Fig. 2. The phase voltage (top trace ) and line-to-line voltages of H-bridge cascaded inverter.

Fig. 3. Source phase voltage (top trace) and source phase Current (bottom trace) with DSTATCOM in closed loop power factor control mode.

Fig. 4. DC link voltage (Vd,) (Top or First Trace), direct and quadrature axis source currents (Second Trace) ,inverter currents Id and Iq (Third Trace) and load reactive current (Bottom Trace).

Fig 5. Individual Capacitor voltages of three level Cascaded H-Bridge Inverter.

CONCLUSION

The paper presents the principle of operation of cascaded H-bridge converter and simulation studies on cascaded converter based DSTATCOM using Sinusoidal PWM control. It is observed that the DSTATCOM is capable of supplying the reactive power demanded by the load both during steady state and transient operating conditions. The harmonics in cascaded H-bridge three-level inverter current are less compared to two-level inverter operating at same switching frequency.

REFERENCES

[1] Jih-Sheng Lal, Fang Zheng Peng,” Multilevel Converters – A New Breed of Power Converters”, IEEE Transactions on Industry Applications, Vol.32, no.3, pp.509,1996.

[2] Muni B.P., Rao S.E., Vithal J.V.R., Saxena S.N., Lakshminarayana S., Das R.L., Lal G., Arunachalam M., “DSTATCOM for Distribution Utility and Industrial Applications”, Conference Proceedings, IEEE, Region Tenth Annual Conference, TENCON-03. Page(s): 278- 282 Vol. 1

[3] Bishnu P. Muni, S.Eswar Rao, JVR Vithal and SN Saxena, “Development of Distribution STATCOM for power Distribution Network” Conference Records, International conference on “Present and Future Trends in Transmission and Convergence”, New Delhi, Dec.2002,pp. VII_26-33.

[4] F.Z. Peng, J. S. Lai, J.W. Mckeever, J. Van Coevering, “A Multilevel Voltage – Source inverter with Separate dc sources for Static Var Generation” IEEE Transactions on Industry Applications, Vol. 32, No. 5, Sep 1996, ppl 130-1138.

[5] K.Anuradha, B.P.Muni, A.D.Rajkumar,” Simulation of Cascaded HBridge Converter Based DSTATCOM” First IEEE Conference on Industrial Electronics and Applications, May 2006, pp 501-505.

Power Electronics Projects Maharashtra

Power Electronics Projects Maharashtra -2015/2016/2017

Download

Contact us:

email: asokatechnologies@gmail.com

website: www.asokatechnologies.in

Asoka technologies provide Power Electronics Projects Telangana

ELECTRICAL ENGINEERING is a field of engineering that generally deals with the study and application of electricity, electronics. This field first became an referable occupation in the later half of the 19th century. After degradation of the electric telegraph, the telephone and electric power distribution and use. Finally, broad casting and recording media made electronics part of daily life.The invention of the transistor, and later the integrated circuit, reduced the cost of electronics. Thus it can be used in almost any household object.

POWER ELECTRONICS is the application of solid-state electronics to the control and conversion of electric power. The first high power electronic devices were mercury-arc valves. In modern systems, the semiconductor switching devices performs the conversion. Examples of these devices are diodes, thyristors and transistors, pioneered by R. D. Middlebrook and others beginning in the 1950s. In contrast to electronic systems, in power electronics substantial amounts of electrical energy are processed. An AC/DC converter (rectifier) is the most typical power electronics device. It is found in many consumer electronic devices, e.g. television sets, personal computers, battery chargers, etc. The power range is typically from tens of watts to several hundred watts. In industry a common application is the variable speed drive (VSD) that is used to control an induction motor. The power range of VSDs start from a few hundred watts and end at tens of megawatts.

An ELECTRIC POWER SYSTEM is a network of electrical components deployed to supply, transfer, and use electric power. An example of an electric power system is the the grid that provides power to an extended area. An electrical grid power system can be broadly divided into the generators,  the transmission system and the distribution system.  The generators supply the power. The transmission system carries the power from the generating centres to the load centres. The distribution system feeds the power to nearby homes and industries. Smaller power systems are also found in industry, hospitals, commercial buildings and homes. The majority of these systems rely upon three-phase AC power—the standard for large-scale power transmission and distribution across the modern world. Specialised power systems that do not always rely upon three-phase AC power are found in aircraft, electric rail systems, ocean liners and automobiles.

Power Electronics Projects Maharashtra

Fixed Switching Frequency Sliding Mode Control for Single-Phase Unipolar Inverters

ABSTRACT:
Sliding mode control (SMC) is recognized as robust controller with a high stability in a wide range of operating conditions, although it suffers from chattering problem. In addition, it cannot be directly applied to multi switches power converters. In this paper, a high performance and fixed switching frequency sliding mode controller is proposed for a single-phase unipolar inverter. The chattering problem of SMC is eliminated by smoothing the control law in a narrow boundary layer, and a pulse width modulator produces the fixed frequency switching law for the inverter. The smoothing procedure is based on limitation of pulse width modulator. Although the smoothed control law limits the performance of SMC, regulation and dynamic response of the inverter output voltage are in an acceptable superior range. The performance of the proposed controller is verified by both simulation and experiments on a prototype 6-kVA inverter. The experimental results show that the total harmonic distortion of the output voltage is less than 1.1% and 1.7% at maximum linear and nonlinear load, respectively. Furthermore, the output dynamic performance of the inverter strictly conforms the standard IEC62040-3. Moreover, the measured efficiency of the inverter in the worst condition is better than 95.5%.
KEYWORDS:
1. Pulse width modulator
2. Sliding mode control
3. Unipolar single phase inverter

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Proposed controller for single-phase inverters with a resonator in voltage loop.

EXPECTED SIMULATION RESULTS:

Fig. 2. Simulation result. a) Output voltage and current at 6-kW linear load. b) Output voltage and current at 6-kVA nonlinear load with CF = 2.75 and PF = +0.7.

Fig. 3. Simulation result: transient response of the output voltage for linear step load from zero to 100%

Fig. 4. Simulation result: transient response of the output voltage for linear
step load from 100% to zero.

Fig. 5. Experimental result: efficiency of inverter versus output power.

CONCLUSION:
In this paper, a fixed frequency SMC was presented for a single-phase inverter. The performance of the proposed controller has been demonstrated by a 6-kVA prototype. Experimental results show that the inverter is categorized in class1 of the IEC64020-3 standard for output dynamic performance. The inverter efficiency was measured up to 95.5% in the worst case.

Since the direct SMC cannot be applied to four switches unipolar inverter and it also suffers from the chattering problem, a PWM is employed to generate a fixed frequency switching law. The PWM modulates the smoothed discontinuous control law which is produced by SMC. To smooth the control law, the limitation of the PWM was considered.

The simulation and experimental results show that the load regulation is about 1% at the steady state as well. But, to obtain better regulation, a resonance compensator was added in the voltage loop. With this compensator, the load regulation was measured which has been below 0.2%.

REFERENCES:
[1] G. Venkataramanan and D.M. Divan, “Discrete time integral sliding mode control for discrete pulse modulated converters,” in Proc. 21st Annu. IEEE Power Electron. Spec. Conf., San Antonio, TX, 1990, pp. 67–73.
[2] J.Y.Hung,W. Gao, and J. C.Hung, “Variable structure control:Asurvey,” IEEE Trans. Ind. Electron., vol. 40, no. 1, pp. 2–22, Feb. 1993.
[3] E. Fossas and A. Ras, “Second order sliding mode control of a buck converter,” in Proc. 41st IEEE Conf. Decision Control, 2002, pp. 346– 347.
[4] C. Rech, H. Pinheiro, H. A. Gr¨undling, H. L. Hey, and J. R. Pinheiro, “A modified discrete control law for UPS applications,” IEEE Trans. Power Electron., vol. 18, no. 5, pp. 1138–1145, Sep. 2003.
[5] K. S. Low, K. L. Zhou, and D.W.Wang, “Digital odd harmonic repetitive control of a single- phase PWM inverter,” in Proc. 30th Annu. Conf. IEEE Ind. Electron. Soc., Busan, Korea, Nov. 2–6, 2004, pp. 6–11.

 

 

Analysis and Mathematical Modelling Of Space Vector Modulated Direct Controlled Matrix Converter

ABSTRACT:

Matrix converters as induction motor drivers have received considerable attention in recent years because of its good alternative to voltage source inverter pulse width modulation (VSI-PWM) converters. This paper presents the work carried out in developing a mathematical model for a space vector modulated (SVM) direct controlled matrix converter. The mathematical expressions relating the input and output of the three phase matrix converter are implemented by using MATLAB/SIMULINK. The duty cycles of the switches are modeled using space vector modulation for 0.5 and 0.866 voltage transfer ratios. Simulations of the matrix converter loaded by passive RL load and active induction motor are performed. A unique feature of the proposed model is that it requires very less computation time and less memory compared to the power circuit realized by using actual switches. In addition, it offers better spectral performances, full control of the input power factor, fully utilization of input voltages, improve modulation performance and output voltage close to sinusoidal.

KEYWORDS:

  1. Matrix Converter
  2. Space Vector Modulation
  3. Simulation Model
  4. Induction Motor

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

image001

Figure 1: Block diagram of simulation model for direct matrix converter

EXPECTED SIMULATION RESULTS:
image002

Figure 2: Result for sector identification

image003

Figure 3: Input and output voltage with passive load for q=0.5; R=135.95Ω, L=168.15mH, Vim=100 V, fo = 60Hz, fs = 2kHz

image004

Figure 4: Input and output voltage with passive load for q=0.866; R=135.95Ω, L=168.15mH, Vim=100 V, fo = 60Hz, fs = 2kHz

 image005

 Figure 5: Input and output voltage with loaded induction motor for q=0.5; 3hp, Rs =0.277Ω, Rr=0.183Ω, Nr=1766.9rpm, Lm=0.0538H, Lr=0.05606H, Ls=0.0533H,fo=60Hz, fs=2kHz

image006

Figure 6: Input and output voltage with loaded induction motor for q=0.866; 3hp, Rs =0.277Ω, Rr=0.183Ω, Nr=1766.9rpm, Lm=0.0538H, Lr=0.05606H, Ls=0.0533H, fo=60Hz, fs=2kHz
image007

Figure 7: Input current with passive load; R=135.95Ω, L=168.15mH, Vim=100 V, fo = 60Hz, fs = 2kHz (a) q=0.5, (b) q = 0.866
image008

 Figure 8: Input current with loaded induction motor for q=0.866; 3hp, Rs =0.277Ω, Rr=0.183Ω, Nr=1766.9rpm, Lm=0.0538H, Lr=0.05606H, Ls=0.0533H, fo=60Hz, fs=2kHz

 CONCLUSION:

The main constraint in the theoretical study of matrix converter control is the computation time it takes for the simulation. This constraint has been overcome by the mathematical model that resembles the operation of power conversion stage of matrix converter. This makes the future research on matrix converter easy and prosperous. The operation of direct control matrix converter was analysed using mathematical model with induction motor load for 0.866 voltage transfer ratio.

 REFERENCES:

[1]. A. Alesina, M.G.B.V., Analysis And Design Of Optimum-Amplitude Nine – Switch Direct AC-AC Converters. IEEE Trans. On Power. Electronic, 1989. 4.

[2]. D. Casadei, G.S., A. Tani, L. Zari, Matrix Converters Modulation Strategies : A New General Approach Based On Space-Vector Representation Of The Switch State. IEEE Trans. On Industrial Electronic, 2002. 49(2).

[3]. P. W. Wheeler, J.R., J. C. Claire, L. Empringham, A. Weinstein, Matrix Converters : A Technology Review. IEEE Trans. On Industrial Electronic, 2002. 49(2).

[4]. H. Hara, E.Y., M. Zenke, J.K. Kang, T. Kume. An Improvement Of Output Voltage Control Performance For Low Voltage Region Of Matrix Converter. In Proc 2004 Japan Industry Applications Society Conference, No. 1-48, 2004. (In Japanese). 2004

[5]. Ito J, S.I., Ohgushi H, Sato K, Odaka A, Eguchi N., A Control Method For Matrix Converter Based On Virtual Ac/Dc/Ac Conversion Using Carrier Comparison Method. Trans Iee Japan Ia 2004. 124-D: P. 457–463.

Analysis and Design of High-Frequency Isolated Dual-Bridge Series Resonant DC/DC Converter

ABSTRACT:

Bidirectional dual-bridge dc/dc converter with high frequency isolation is gaining more attentions in renewable energy system due to small size and high-power density. In this paper, a dual-bridge series resonant dc/dc converter is analyzed with two simple modified ac equivalent circuit analysis methods for both voltage source load and resistive load. In both methods, only fundamental components of voltages and currents are considered. All the switches may work in either zero-voltage-switching or zero-current-switching for a wide variation of voltage gain, which is important in renewable energy generation. It is also shown in the second method that the load side circuit could be represented with an equivalent impedance. The polarity of cosine value of this equivalent impedance angle reveals the power flow direction. The analysis is verified with computer simulation results. Experimental data based on a 200 W prototype circuit is included for validation purpose.

 KEYWORDS:

  1. Analysis and simulation
  2. Dc-to-dc converters
  3. Modeling
  4. Renewable energy systems
  5. Resonant converters

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 image001

Fig. 1. Hybrid renewable energy generation system with battery back-up function.

EXPECTED SIMULATION RESULTS:
image002

 Fig. 2. Output power versus phase-shift angle φ. (a) F = 1.1, M = 0.95,

and different Q. (b) F = 1.1, Q = 1, and different converter gain M.

image003

Fig. 3. Operation in charging mode (Vi = 110 V, Vo = 100 V), simulated waveforms of vAB and vCD , resonant current iS , resonant capacitor voltage vCs , output current before filter capacitor io for output power (a) Po = 200W, (b) Po = 100 W, and (c) Po = 20 W.
image004

Fig. 4. Operation in regeneration mode (Vi = 110V, Vo = 100 V). Simulated waveforms of vAB and vCD , resonant current iS , resonant capacitor voltage vCs , output current before filter capacitor io for output power Po = −200 W.

image005

Fig. 5. Full-load test results (Vi = 110 V, Vo = 100 V). (a) From top to bottom vAB (100V/div), vCD (100V/div), is (2A/div). (b) vC (100V/div). (c) Primary switch current (1A/div). (d) Secondary switch current (1A/div).

image006

Fig. 6. (a) Half-load test results (Vi = 110 V, Vo = 100 V): from top to bottom: vAB (100 V/div), vCD (100 V/div), is (2 A/div), primary switch current (1 A/div), secondary switch current (1 A/div). (b) 10% load condition test results (Vi = 110 V, Vo = 100 V): from top to bottom: waveforms of (a) repeated.

image007

Fig. 7. Output current of secondary converter under different load levels (Vi = 110 V, Vo = 100 V). (a) 200 W (2A/div). (b) 100 W (2A/div). (c) 20 W (1A/div).

CONCLUSION:

In this paper, a HF isolated dual-bridge series resonant dc/dc converter has been proposed, which is suitable for renewable energy generation applications. Two modified ac equivalent circuit analysis methods were presented to analyze the DBSRC. First method used was voltage-source type of load, whereas, second method uses a controlled rectifier with resistive load. It was shown that an equivalent impedance could be used to represent the secondary part circuit in the case of resistive load to include the bidirectional feature. Detailed analysis has been presented for both the methods. Same results were obtained from both the methods. ZVS turn-ON for primary-side switches and ZCS turn-OFF for secondary-side switches could be achieved for all load and input/output voltage conditions. Design procedure has been illustrated by a 200Wdesign example. Through the SPICE simulation and experimental results, the theoretical results have been verified.

In the DAB converter, performance of the converter is heavily dependent on the leakage inductance of the transformer (used for power transfer and should be as small as possible) [15], [19], whereas, in the DBSRC, leakage inductance is used as part of resonant tank. If the DAB converter is used for application with wide input/output voltage variation, ZVS of primary-side converter may be hard to achieve [19]. DBSRC has low possibility of transformer saturation due to the series capacitor (that can be split as mentioned earlier). The disadvantage of DBSRC is the size of resonant tank (additional capacitor), which brings extra size and cost. Further work is required to compare the DAB converter with the DBSRC for such applications. In the future, more study will be done based on the DBSRC. Efforts will focus on modifications to realize ZVS on the secondary side to reduce the switching losses further. With all two quadrant switches replaced with four-quadrant switches [23], the converter could be controlled as an ac/ac electronic transformer, which can be used in doubly fed induction generator (DFIG) based wind generation system. For high-power applications, multicells of the converter may be used to meet high power density requirements.

REFERENCES:

[1] L. H. Hansen, L. Helle, F. Blaabjerg, E. Ritchie, S. Munk-Nielsen, H. Bindner, P. Sørensen, and B. Bak-Jenseen, “Conceptual survey of generators and power electronics for wind turbines,” Risø Nat. Lab., Roskilde, Denmark, Tech. Rep. Risø-R-1205(EN), ISBN 87-550-2743-8, Dec. 2001.

[2] N. Kasa, Y. Harada, T. Ida, and A. K. S. Bhat, “Zero-current transitions converters for independent small scale power network system using lower power wind turbines,” in Proc. IEEE Int. Symp. Power Electron., Electric Drives, Autom. Motion 2006, May 23–26, pp. 1206–1210.

[3] J. Lai and D. J. Nelson, “Energy management power converters in hybrid electric and fuel cell vehicles,” Proc. IEEE, vol. 95, no. 4, pp. 766–777, Apr. 2007.

[4] H. Tao, A. Kotsopoulos, J. L. Duarte, andM. A.M. Hendrix, “Multi-input bidirectional dc-dc converter combining dc-link and magnetic-coupling for fuel cell systems,” in Proc. 40th IEEE IAS Annu. Meet., Oct. 2005, vol. 3, pp. 2021–2028.

[5] F. Z. Peng, H. Li, G.-J. Su, and J. S. Lawler, “A new ZVS bidirectional dc–dc converter for fuel cell and battery application,” IEEE Trans. Power Electron., vol. 19, no. 1, pp. 54–65, Jan. 2004.

A Comparison of Soft-Switched DC-to-DC Converters for Electrolyzer Application

ABSTRACT:

An electrolyzer is part of a renewable energy system and generates hydrogen from water electrolysis that is used in fuel cells. A dc-to-dc converter is required to couple the electrolyzer to the system dc bus. This paper presents the design of three soft-switched high-frequency transformer isolated dc-to-dc converters for this application based on the given specifications. It is shown that LCL-type series resonant converter (SRC) with capacitive output filter is suitable for this application. Detailed theoretical and simulation results are presented. Due to the wide variation in input voltage and load current, no converter can maintain zero-voltage switching (ZVS) for the complete operating range. Therefore, a two-stage converter (ZVT boost converter followed by LCL SRC with capacitive output filter) is found suitable for this application. Experimental results are presented for the two-stage approach which shows ZVS for the entire line and load range.

KEYWORDS:

  1. DC-to-DC converters
  2. Electrolyzer
  3. Renewable energy system (RES)
  4. Resonant converters.

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:
image001

 Fig. 1. Block diagram of a typical RES.

 EXPECTED SIMULATION RESULTS:
image002

Fig. 2. Simulation waveforms for LCL SRC with capacitive output filter at full-load (2.4 kW) with Vin = 40V and Vo = 60V: inverter output voltage vab ; current through resonant tank inductor iLr ; switch currents (iS 1iS 4 ); rectifier input voltage (vrectin ); voltage across and current through output rectifier diode DR1 .

image003

Fig. 3. Simulation waveforms of Fig. 13 repeated for LCL SRC with capacitive output filter at 10% load with Vin = 40V and Vo = 60V.

image004

Fig. 4. Experimental waveforms obtained for two stage converter cell (see Fig. 15) at full-load (2.4 kW) with Vin = 40V and Vo = 60V. (a) Voltage vSW across drain-to-source of boost switch (SW) and gating signal vg to the boost switch. (b) Inverter output voltage vab and current through resonant tank inductor iLr . (c) Rectifier input voltage vrectin and current through parallel inductor Lt , iLt . (d) Rectifier input voltage vrectin and secondary current isec . Scales: (a) vSW (40V/div) and vg (10V/div). (b) vab (100 V/div) and iLr (20A/div) (c) vrectin (100 V/div) and iLt (20A/div). (d) vrectin (100 V/div) and isec (20A/div).

image005

 Fig. 5. Experimental waveforms of Fig. 17 repeated for Vin = 40V and Vo = 40V at Id = 10 A. Scales: (a) vSW (40V/div) and vg (10V/div). (b) vab (40V/div) and iLr (20A/div). (c) vrectin (100 V/div) and iLt (20A/div). (d) vrectin (100 V/div) and isec (20A/div).

image006

Fig. 6. Experimental waveforms of Fig. 17 repeated for Vin = 60V and Vo = 40V at Id = 10 A. Scales: (a) vSW (40V/div) and vg (10V/div). (b) vab (40V/div) and iLr (20A/div). (c) vrectin (100 V/div) and iLt (20A/div). (d) vrectin (100 V/div) and isec (20A/div).

 CONCLUSION:

 A comparison of HF transformer isolated, soft-switched, dc to- dc converters for electrolyzer application was presented. An interleaved approach with three cells (of 2.4kWeach) is suitable for the implementation of a 7.2-kW converter. Three major configurations designed and compared are as follows: 1) LCL SRC with capacitive output filter; 2) LCL SRC with inductive output filter; and 3) phase-shifted ZVS PWM full-bridge converter. It has been shown that LCL SRC with capacitive output filter has the desirable features for the present application. Theoretical predictions of the selected configuration have been compared with the SPICE simulation results for the given specifications. It has been shown that none of the converters maintain ZVS for maximum input voltage. However, it is shown that LCL-type SRC with capacitive output filter is the only converter that maintains soft-switching for complete load range at the minimum input voltage while overcoming the drawbacks of inductive output filter. But the converter requires low value of resonant inductor Lr for low input voltage design. Therefore, it is better to boost the input voltage and then use the LCL SRC with capacitive output filter as a second stage. When this converter is operated with almost fixed input voltage, duty cycle variation required is the least among all the three converters while operating with ZVS for the complete variations in input voltage and load. A ZVT boost converter with the specified input voltage (40–60 V) will generate approximately 100V as the input to the resonant converter for Vo = 60V. Therefore, we have investigated the performance of a ZVT boost converter followed by the LCL SRC with capacitive output filter. It was shown experimentally that the two-stage approach obtained ZVS for all the switches over the complete operating range and also simplified the design of resonant converter.

REFERENCES:

[1] A. P. Bergen, “Integration and dynamics of a renewable regenerative hydrogen fuel cell system,” Ph.D. dissertation, Dept. Mechanical Eng., Univ. Victoria, Victoria, BC, Canada, 2008.

[2] D. Shapiro, J. Duffy, M. Kimble, and M. Pien, “Solar-powered regenerative PEM electrolyzer/fuel cell system,” J. Solar Energy, vol. 79, pp. 544–550, 2005.

[3] F. Barbir, “PEM electrolysis for production of hydrogen from renewable energy sources,” J. Solar Energy, vol. 78, pp. 661–669, 2005.

[4] R. L. Steigerwald, “High-frequency resonant transistor DC-DC converters,”IEEE Trans. Ind. Electron., vol. 31, no. 2, pp. 181–191, May 1984.

[5] R. L. Steigerwald, “A Comparison of half-bridge resonant converter topologies,” IEEE Trans. Power Electron., vol. 3, no. 2, pp. 174–182, Apr. 1988.

 

A Comparison of Half Bridge & Full Bridge Isolated DC-DC Converters for Electrolysis Application

ABSTRACT:

This paper presents a comparison of half bridge and full bridge isolated, soft-switched, DC-DC converters for Electrolysis application. An electrolyser is a part of renewable energy system which generates hydrogen from water electrolysis that used in fuel cells. A DC-DC converter is required to couple electrolyser to system DC bus. The proposed DC-DC converter is realized in both full-bridge and half-bridge topology in order to achieve zero voltage switching for the power switches and to regulate the output voltage. Switching losses are reduced by zero voltage switching. Switching stresses are reduced by using resonant inductor and capacitor. The proposed DC-DC converter has advantages like high power density, low EMI, reduced switching stresses, high circuit efficiency and stable output voltage. The MATLAB simulation results show that the output of converter is free from the ripples and regulated output voltage and this type of converter can be used for electrolyser application. Experimental results are obtained from a MOSFET based DC-DC Converter with LC filter. The simulation results are verified with the experimental results.

KEYWORDS:

  1. DC-DC converter
  2. Electrolyser
  3. Renewable energy sources
  4. Resonant converter
  5. TDR

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 image001

Fig 1. Half Bridge DC-DC Converter.

image002

Fig 2. Full Bridge DC-DC Converter.

 EXPECTED SIMULATION RESULTS:

 image003

Fig 3 (b) Driving Pulses

image004

Fig 4 (c) Inverter output voltage with LC filter

image005

Fig 5 (d) Transformer secondary voltages

image006

Fig 6 (e) Output voltage and current

image007

Fig 7 (b) Driving Pulses

image008

Fig 8 (c) Inverter output voltage with LC filter

image009

Fig 9 (d) Transformer secondary voltage

image010

Fig 10 (e) Output voltage and current

 CONCLUSION:

 A comparison of half bridge and full bridge isolated DC-DC converters for Electrolysis application are presented. DC-DC converters for electrolyser system is simulated and tested with LC filter at the output. The electrical performances of the converter have been analyzed. The simulation and experimental results indicate that the output of the inverter is nearly sinusoidal. The output of rectifier is pure DC due to the presence of LC filter at the output. Switching losses are reduced by zero voltage switching. Switching stresses are reduced by using resonant inductor and capacitor The advantages of resonant converter are reduced (di/dt), low switching losses and high efficiency. Switching losses are reduced by zero voltage switching. Switching stresses are reduced by using resonant inductor and capacitor The converter maximizes the efficiency through the zero voltage switching and the use of super-junction MOSFET as switching devices with high dynamic characteristics and low direct voltage drop. Half bridge converter is found to be better than that of full bridge converter.

REFERENCES:

[1] E.J.Miller, “Resonant switching power conversion,”in Power Electronics Specialists Conf.Rec., 1976, pp. 206-211.

[2] V. Volperian and S. Cuk , “A complete DC analysis of the series resonant converter”, in IEEE power electronics specialists conf. Rec. 1982, pp. 85-100.

[3] R.L. Steigerwald, “High-Frequency Resonant Transistor DC-DC Converters”, IEEE Trans. On Industrial Electronics, vol.31, no.2, May1984, pp. 181-191.

[4] D.J. Shortt, W.T. Michael, R.L. Avert, and R.E. Palma, “A 600 W four stage phase-shifted parallel DC-DC converter,”, IEEE Power Electronics Specialists Conf., 1985, pp. 136-143.

[5] V. Nguyen, J. Dhayanchand, and P. Thollot, “A multiphase topology series-resonant DC-DC converter,” in Proceedings of Power Conversion International, 1985, pp. 45-53.

An Ultracapacitor Integrated Power Conditioner for Intermittency Smoothing and Improving Power Quality of Distribution Grid

ABSTRACT:

Penetration of various types of distributed energy resources (DERs) like solar, wind, and plug-in hybrid electric vehicles (PHEVs) onto the distribution grid is on the rise. There is a corresponding increase in power quality problems and intermittencies on the distribution grid. In order to reduce the intermittencies and improve the power quality of the distribution grid, an ultracapacitor (UCAP) integrated power conditioner is proposed in this paper. UCAP integration gives the power conditioner active power capability, which is useful in tackling the grid intermittencies and in improving the voltage sag and swell compensation. UCAPs have low energy density, high-power density, and fast charge/discharge rates, which are all ideal characteristics for meeting high-power low-energy events like grid intermittencies, sags/swells. In this paper, UCAP is integrated into dc-link of the power conditioner through a bidirectional dc–dc converter that helps in providing a stiff dc-link voltage. The integration helps in providing active/reactive power support, intermittency smoothing, and sag/swell compensation. Design and control of both the dc–ac inverters and the dc–dc converter are discussed. The simulation model of the overall system is developed and compared with the experimental hardware setup.

KEYWORDS:

  1. Active power filter (APF)
  2. Dc–dc converter
  3. D–q control
  4. Digital signal processor (DSP)
  5. Dynamic voltage restorer (DVR)
  6. Energy storage integration
  7. Sag/swell
  8. Ultracapacitors (UCAP)

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 image001

Fig. 1. One-line diagram of power conditioner with UCAP energy storage.

EXPECTED SIMULATION RESULTS:

 image002

Fig. 2. (a) Source and load rms voltages Vsrms and VLrms during sag. (b) Source voltages Vsab (blue), Vsbc (red), and Vsca (green) during sag. (c) Injected voltages Vinj2a (blue), Vinj2b (red), and Vinj2c (green) during sag. (d) Load voltages VLab (blue), VLbc (red), and VLca (green) during sag.

image003

Fig. 3. (a) Currents and voltages of dc–dc converter. (b) Active and reactive

power of grid, load, and inverter during voltage sag.

 CONCLUSION:

In this paper, the concept of integrating UCAP-based rechargeable energy storage to a power conditioner system to improve the power quality of the distribution grid is presented. With this integration, the DVR portion of the power conditioner will be able to independently compensate voltage sags and swells and the APF portion of the power conditioner will be able to provide active/reactive power support and renewable intermittency smoothing to the distribution grid. UCAP integration through a bidirectional dc–dc converter at the dc-link of the power conditioner is proposed. The control strategy of the series inverter (DVR) is based on inphase compensation and the control strategy of the shunt inverter (APF) is based on id iq method. Designs of major components in the power stage of the bidirectional dc–dc converter are discussed. Average current mode control is used to regulate the output voltage of the dc–dc converter due to its inherently stable characteristic. A higher level integrated controller that takes decisions based on the system parameters provides inputs to the inverters and dc–dc converter controllers to carry out their control actions. The simulation of the integrated UCAP-PC system which consists of the UCAP, bidirectional dc–dc converter, and the series and shunt inverters is carried out using PSCAD. The simulation of the UCAP-PC system is carried out using PSCAD. Hardware experimental setup of the integrated system is presented and the ability to provide temporary voltage sag compensation and active/reactive power support and renewable intermittency smoothing to the distribution grid is tested. Results from simulation and experiment agree well with each other thereby verifying the concepts introduced in this paper. Similar UCAP based energy storages can be deployed in the future in a microgrid or a low-voltage distribution grid to respond to dynamic changes in the voltage profiles and power profiles on the distribution grid.

 REFERENCES:

[1] N. H. Woodley, L. Morgan, and A. Sundaram, “Experience with an inverter-based dynamic voltage restorer,” IEEE Trans. Power Del., vol. 14, no. 3, pp. 1181–1186, Jul. 1999.

[2] J. G. Nielsen, M. Newman, H. Nielsen, and F. Blaabjerg, “Control and testing of a dynamic voltage restorer (DVR) at medium voltage level,” IEEE Trans. Power Electron., vol. 19, no. 3, pp. 806–813, May 2004.

[3] V. Soares, P. Verdelho, and G. D. Marques, “An instantaneous active and reactive current component method for active filters,” IEEE Trans. Power Electron., vol. 15, no. 4, pp. 660–669, Jul. 2000.

[4] H. Akagi, E. H. Watanabe, and M. Aredes, Instantaneous Reactive Power Theory and Applications to Power Conditioning, 1st ed. Hoboken, NJ, USA: Wiley/IEEE Press, 2007.

[5] K. Sahay and B. Dwivedi, “Supercapacitors energy storage system for power quality improvement: An overview,” J. Energy Sources, vol. 10, no. 10, pp. 1–8, 2009.

Design of a multilevel inverter with reactive power Control ability for connecting PV cells to the grid

 

ABSTRACT:  

With the increasing use of PV cells in power system, optimal utilization of the equipment is an important issue. In these systems the MPPT controller is used to inject the maximum available power from solar energy. During day time that the active power decreases because of low intensity, the inverter is capable of injecting reactive power up to its nominal capacity and this is a chance for reactive power compensation. In this paper the aim is to propose a control method for injecting the maximum active power and if possible, the reactive power. In addition, a low pass filter is suggested to solve the problem of current fluctuations in case of unbalanced load. Simulation results on a typical system in MATLAB indicate proper performance of the presented method.

KEYWORDS:

 NPC inverter

Maximum Power Point Tracking (MPPT)

Photovoltaic cell (PV)

PI current control

Space vector pulse width modulation (SVPWM)

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 image001

Fig1. Studied system for injecting power to the grid and local load

EXPECTED SIMULATION RESULTS:
image002

Figure2. output active and reactive power of the inverter

image003

Figure3. THD of injected current to the grid in no-load condition

image004

Figure4. Injecting active power in no-load condition and low intensity of light

image005

Figure5. load increase at t=0.5s and its effects on active and reactive power

image006

Figure6. Injected voltage and current to the grid and the effect of inductive load on current

image007

Figure7. Analyzing THD of injected current to the grid in PeL=50kw and PQL=30kvar condition

image008

Figure8. Power increment in two levels: a. at t=0.5s and b. at t=0.7s

image009

Figure9. Output power of inverter and the grid

image010

Figure10. Output voltage and current after using filter and limiter

image011

Figure11. THD of circuit when PeL=50kw and PQL=30kvar and using filter and limiter

CONCLUSION:

In this paper a control strategy is proposed for current control of PV inverter that control s maximum generated active power and reactive power compensation of local load simultaneously .The main idea is to utilize inverter for reactive power injection during active power decrement .using a low pass filter and power limiter in control system , produced oscillations due to unbalanced load is eliminated and inverter works in safe condition simulation results show the proposed method to be viable in controlling inverter

REFERENCES:

[1] Chung-ChuanHou,Chih-Chung Shih, Po-Tai Cheng,Ahmet M. Hava, Common-Mode Voltage Reduction Pulsewidth

Modulation Techniques for Three-Phase Grid-Connected Converters , IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 28, NO. 4, APRIL 2013

[2] GeorgiosTsengenes, Thomas Nathenas, Georgios Adamidis,” A three-level space vector modulated grid connected inverter with control scheme based on instantaneous power theory”, Simulation Modelling Practice and Theory 25 (2012) 134–147

[3] S. Kouro, K. Asfaw, R. Goldman, R. Snow, B. Wu, and J. Rodríguez, NPC Multilevel Multistring Topology for Larg Scale Grid Connected Photovoltaic Systems,2010 2nd IEEE International Symposium on Power Electronics for Distributed Generation Systems

[4] Georgios A. Tsengenes, Georgios A. Adamidis, Study of a Simple Control Strategy for Grid

Connected VSI Using SVPWM and p-q Theory,XIX International Conference on Electrical Machines – ICEM 2010, Rome

[5] César Trujillo Rodríguez, David Velasco de la Fuente, Gabriel Garcerá, Emilio Figueres, and Javier A. Gua can eme Moreno,Reconfigurable Control Scheme for a PV

2016-17 IEEE Electrical Projects List