Operation of Series and Shunt Converters with 48-pulse Series Connected Three-level NPC Converter for UPFC

ABSTRACT:

The 48-pulse series connected 3-level Neutral Point Clamped (NPC) converter approach has been used in Unified Power Flow Controller (UPFC) application due to its near sinusoidal voltage quality. This paper investigates the control and operation of series and shunt converters with 48-pulse Voltage Source Converters (VSC) for UPFC application. A novel controller for series converter is designed based on the “angle control” of the 48-pulse voltage source converter. The complete simulation model of shunt and series converters for UPFC application is implemented in Matlab/Simulink. The practical real and reactive power operation boundary of UPFC in a 3-bus power system is specifically investigated. The performance of UPFC connected to the 500-kV grid with the proposed controller is evaluated. The simulation results validate the proposed control scheme under both steady state and dynamic operating conditions.

KEYWORDS:

1.      48-pulse converter

2.      Neutral Point Clamped (NPC) converter

3.      Angle control

4.      Unified Power Flow Controller (UPFC)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1 Schematic of Unified Power Flow Controller (UPFC)

Fig. 2. 48-pulse VSC based +100 MVA UPFC in a 3-bus power system

EXPECTED SIMULATION RESULTS:

Fig.3 Line real power (top) and reactive power (bottom) references (MVA)

Fig. 4 Measured real and reactive power, DC link voltage and converter angles (Top trace: measured line real power (MW); second top trace: measured line reactive power, (MVar ); third top trace: DC bus voltage; fourth top trace: shunt converter angle α ; fifth top trace: series converter angle α ; bottom trace: series converter angle σ ).

Fig.5 Shunt converter output voltage (blue), Line voltage (green) and shunt

converter current (red) (5.42s-5.48s)

Fig.6 Shunt converter real power (blue, p.u.), reactive power (green, p.u.).

Fig.7 Current (p.u.) of transmission line L1.

Fig.8 Series converter 48 pulse converter voltage (blue, p.u.) and current

(black, p.u.) during time 2~2.03s (when real power reference is increased)

Fig.9 Series converter angle σ vs. DC bus voltage (Top trace: line real

power and reactive power; second top trace: shunt converter injected reactive

power; third top trace: DC bus voltage; bottom trace: series converter

angle σ )

 CONCLUSION:

In this paper, the control and operation of series and shunt converters with 48-pulse series connected 3-level NPC converter for UPFC application are investigated. A new angle controller for 48-pulse series converter is proposed to control the series injection voltage, and therefore the real and reactive power flow on the compensated line. The practical UPFC real and reactive power operation boundary in a 3-bus system is investigated; this provides a benchmark to set the system P and Q references. The simulation of UPFC connected to the 500-kV grid verifies the proposed controller and the independent real power and reactive power control of UPFC with series connected transformer based 48-pulse converter.

REFERENCES:

[1] N. G. Hingorani, "Power electronics in electric utilities: role of power electronics in future power systems," Proceedings of the IEEE, vol. 76, pp. 481, 1988.

[2] N. G. Hingorani and L. Gyugyi, Understanding FACTS: concepts and technology of flexible AC transmission systems: IEEE Press, 2000.

[3] L. Gyugyi, "Dynamic compensation of AC transmission lines by solid-state synchronous voltage sources," IEEE Transactions on Power Delivery, vol. 9, pp. 904, 1994.

[4] C. D. Schauder, L. Gyugyi etc. “Operation of the unified power flow controller (UPFC) under practical constraints,” IEEE Transactions on Power Delivery, vol. 13, pp. 630-639, April 1998.

[5] L. Gyugyi. “Unified power-flow control concept for flexible AC transmission systems,” IEE Proceedings - Generation, Transmission and Distribution, vo. 139, pp. 323-331, July 1992.

Analysis of 12 Pulse Phase Control AC/DC Converter

ABSTRACT:

In this paper, the unbalanced current in the 12- pulse phase control AC/DC converters was studied. The 12- pulse A-Y type AClDC converter will keep a balanced voltage with 30" phase shifted at the low coupling coefficient condition. But an unbalanced current will be obtained in the 12-pulse autotransformer phase shift AClDC converter at the low coupling coefficient condition. The theoretical phasor analysis of the unbalanced current was presented and a feedback controller was designed to overcome this problem. Finally, a 3 kW 12-pulse autotransformer phase shifted AClDC converter was implemented to demonstrate the theoretical analysis.

KEYWORDS:

1.      12 Pulse AClDC Converter

2.      Phase Controller

3.      Autotransformer

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Conventional 12-pulse AClDC converter.

(a) A-Y isolated transformer.

(b) Autotransformer phase shifted.

Fig. 2. 12-pulse phase control A-Y connected AC/DC converter.

Fig. 3. I;!-pulse phase control autotransformer connected AC/DC

converter.

EXPECTED SIMULATION RESULTS:

Fig. 4 The output current io, and io, of 12-pulse phase control A-Y

typ: transformer ACDC converter with K=0.96 and a = 30"

Fig 5 The output current io, and io, of 12-pulse autotransformer

phase shift ACDC converter with K=0.96 and a = 30".

Fig. 6 The output current of 12-pulse autotransformer connected

AC/DC converter with the controller

Fig. 7 Experimental results for a resistive load without controller

Fig. 8 Experimental results for a resistive load with controller

CONCLUSION:

In this paper, the 12-pulse phase control ACDC converters with A-Y type and autotransformer type are analyzed and studied. The theoretical analysis is presented and the computer simulation results are performed. The 12- pulse A-Y type ACDC converter can function well under any firing condition. However, a serious unbalanced circulation current exists in the autotransformer connected ACDC converter at the non-unity coupling coefficient conditions. Finally, a 3 kW 12-pulse autotransformer phase controlled ACDC converter was implemented to demonstrate the theoretical analysis.

REFERENCES:

1. S. Choi, A. Jouanne, P. Enjeti and 1. Pitel, “New Polyphase Transformer Arrangements with Reduced kVA Capacities for Harmonic Current Reduction in Rectifier Type Utility Interface,“ IEEE PESC, 1995.

2. S. Choi, P. N. Enjeti, H. Lee and I. J. Pitel, “A New Active Interphase Reactor for 12-Pulse Rectifiers Provides Clean Power Utility Interface,” IEEE IAS, pp.2468-2474, 1995.

3. G. Oliver, G. E. April, E. Ngandui and C. Guimaraes, “Novel Transformer Connection to Improve Current Sharing on High Current DC Rectifier,” IEEE IAS, pp.986-962, 1993.

4. S. Miyairi, etc.al, “New Method for Reducing Harmonic Involved in Input and Output of Rectifier with Interphase Transformer,” IEEE Trans. On Industry Applications, Vol. IA-22, No.5, pp.790- 797, SepIOct, 1986.

5. A .R. Prasad, P. D. Ziogas, and S. Manias, “An Active Power Factor Correction Technique for Three-phase Diode Rectifier,” IEEE Trans. on Power Electronics, Vo1.6, No.1, pp.83-92, 1991

Advanced Hybrid System for Solar Car

Abstract

A three-input hybrid system for solar car is designed in this project. It consists of one unidirectional input power port and two bidirectional power ports with a storage element. Depending on utilization state of the battery, three different power operation modes are defined for the converter. Battery charging in the system is carried out from the amorphous solar panel mounted on the body and a solar energy harvesting charging station. Since the solar energy is directly given to the DC load, the efficiency of the system will improve. The capacitor which is connected to the lead acid battery will charge at off peak hours and discharge during the acceleration time of the car. In this proposed system energy wasted in the brakes are also recovered and used to charge the lead acid battery. Hence competent Hybrid Electric Vehicle was developed by using super capacitor and regenerative braking scheme.

Keywords

1.      PhotovoItaic array

2.       Super capacitor                         

3.      Regenerative braking

4.       DC-DC Converter

Software: MATLAB/SIMULINK

Block Diagram:

Figure 1: When the vehicle is moving on a plane

Figure 2: When the vehicle is ascending through the slope

Figure 3: When the vehicle is descending through the slope

Expected Simulation Results:

Figure 4: Output voltage of solar cell

Figure 5: Output voltage of Boost converter

Figure 6: Voltage across super capacitor

Figure 7: armature current

Figure 8: Speed of Armature

Figure 9: input current to the motor

Figure 10: Discharging current from the super capacitor

Figure 11: speed of Armature

Figure 12: generated current

Conclusion

At current levels of technology, installing a super capacitor with regenerative braking scheme provides a feasible method to improve the performances of the vehicles. The simulation results of the proposed systems show that the performance of the vehicle was improved in the following aspects.

(1) Provide better working conditions for the battery and increase its operating life.

(2) Source of energy extended up to the, regenerative braking scheme along with solar source, will increase the system reliability.

(3) Since the super capacitors have the ability to provide a large current in short time acceleration, performance of the vehicle will improve. Future scope of this work is to realize hardware model of the system.

References

[I] Bin Wu, Fang Zhuo, Fei Long, WeiweiGu, Yang Qing, YanQinLiu"A management strategy for solar panel battery -super capacitor hybrid energy system in solar car" 8th International Conference on Power Electronics - ECCE Asia May 30-June 3, 2011

[2] HyunjaeYoo; Seung-Ki SuI; Yongho Park; JongchanJeong; , "System Integration and Power-Flow Management for a Series Hybrid Electric Vehicle Using Super capacitors and Batteries," Industry Applications, IEEE Transactions on , vo1.44, no.l, pp.I08-114, Jan.-Feb. 2008

[3] Jinrui N, Zhifu W', Qinglian "Simulation and Analysis of Performance of a Pure Electric Vehicle with a Super-capacitor"2006 IEEE.

[4] T. Smith, 1. Mars, and G. Turner, "Using super capacitors to improve battery performance," in Proc. IEEE Conf.PESC02, Jun., vol. 1, pp. 124-128.

[5] R. Schupbach, 1. C. Balda, "The role of Ultracapcitors in an Energy Storage Unit for Vehicle Power Management", IEEE Proceedings of the 58^th Vehicular Technology Conference, VTC 2003-Fall, Vol.3, 6-9 October 2003, Orlando,Florida.

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Asoka Technologies

An Integrated Hybrid Power Supply for Distributed Generation Applications Fed by Nonconventional Energy Sources

ABSTRACT

A new, hybrid integrated topology, fed by photovoltaic (PV) and fuel cell (FC) sources and suitable for distributed generation applications, is proposed. It works as an uninterruptible power source that is able to feed a certain minimum amount of power into the grid under all conditions. PV is used as the primary source of power operating near maximum power point (MPP), with the FC section (block), acting as a current source, feeding only the deficit power. The unique “integrated” approach obviates the need for dedicated communication between the two sources for coordination and eliminates the use of a separate, conventional dc/dc boost converter stage required for PV power processing, resulting in a reduction of the number of devices, components, and sensors. Presence of the FC source in parallel (with the PV source) improves the quality of power fed into the grid by minimizing the voltage dips in the PV output. Another desirable feature is that even a small amount of PV power (e.g., during low insolation), can be fed into the grid. On the other hand, excess power is diverted for auxiliary functions like electrolysis, resulting in an optimal use of the energy sources. The other advantages of the proposed system include low cost, compact structure, and high reliability, which render the system suitable for modular assemblies and “plug-n-play” type applications. All the analytical, simulation results of this research are presented.

INDEX TERMS: Buck-boost, distributed generation, fuel cell, grid-connected, hybrid, maximum power point tracking (MPPT), photovoltaic.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM

Fig. 1. Various HDGS configurations. (a) Conventional, multistage topology using two H-bridge inverters [4], [6]. (b) Modified topology with only one H-bridge inverter [4]. (c) Proposed topology. λ denotes solar insolation (Suns).

SIMULATION RESULTS

Fig. 2. Simulation results of the integrated hybrid configuration showing transition from mode III to mode II and then to mode I. T1 and T2 denote the transition between mode III to mode II and mode II to mode I respectively.

Fig. 3. Simulation results of the integrated hybrid configuration operating in electrolysis mode (mode I to mode III and then to mode I). T1 and T2 denote the transition between mode I to mode III and mode III to mode I respectively.

Fig.4. Performance comparison of the proposed HDGS system with and without an FC source in parallel with the PV source.

CONCLUSION

A compact topology, suitable for grid-connected applications has been proposed. Its working principle, analysis, and design procedure have been presented. The topology is fed by a hybrid combination of PV and FC sources. PV is the main source, while FC serves as an auxiliary source to compensate for the uncertainties of the PV source. The presence of FC source improves the quality of power (grid current THD, grid voltage profile, etc.) fed into the grid and decreases the time taken to reach theMPP. Table IV compares the system performance with and without the FC block in the system. A good feature of the proposed configuration is that the PV source is directly coupled with the inverter (and not through a dedicated dc–dc converter) and the FC block acts as a current source. Considering that the FC is not a stiff dc source, this facilitates PV operation at MPP over a wide range of solar insolation, leading to an optimal utilization of the energy sources. The efficiency of the proposed system in mode-1 is higher (around 85% to 90%) than mode 2 and 3 (around 80% to 85%).

REFERENCES

[1] J. Kabouris and G. C. Contaxis, “Optimum expansion planning of an unconventional generation system operating in parallel with a large scale network,” IEEE Trans. Energy Convers., vol. 6, no. 3, pp. 394–400, Sep. 1991.

[2] P. Chiradeja and R. Ramakumar, “An approach to quantify the technical benefits of distributed generation,” IEEE Trans. Energy Convers., vol. 19, no. 4, pp. 764–773, Dec. 2004.

[3] Y. H. Kim and S. S. Kim, “An electrical modeling and fuzzy logic control of a fuel cell generation system,” IEEE Trans. Energy Convers., vol. 14, no. 2, pp. 239–244, Jun. 1999.

[4] K. N. Reddy and V. Agarwal, “Utility interactive hybrid distributed generation scheme with compensation feature,” IEEE Trans. Energy Convers., vol. 22, no. 3, pp. 666–673, Sep. 2007.

[5] K. S. Tam and S. Rahman, “System performance improvement provided by a power conditioning subsystem for central station photovoltaic fuel cell power plant,” IEEE Trans. Energy Convers., vol. 3, no. 1, pp. 64–70.