Modeling and Simulating For Transient Stability Analysis of Power System Using Dynamic Phasor

ABSTRACT:

In this paper, using a new solution method, the phasor simulation, a model of two-machine power system with static var compensators (SVC) and power system stabilizers (PSS) is built. By this system model, the transient stability analysis of this two machine power system when single-phase fault and 3-phase fault is simulated. The result shows that the phasor solution method can reduce simulation time greatly of power grids ,and has good precision.

KEYWORDS:

1.      Multi-machine power system

2.      Static var compensators (SVC)

3.       Transient stability

4.      Simulation

5.      Dynamic phasor

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

CONCLUSION:

Through apply the phasor solution method to modeling and simulation for the transient stability analysis of a simple transmission system containing two hydraulic power plants, shows that the phasor solution method can reduce the system simulation time greatly and has good precision. This solution method still can be applied to simulate more complex power grids.

REFERENCES:

[1] Venkatasubramanian V．Tools for dynamic analysis of the general large power system using time-varying phasors[J]. International Journal on Electric Power and Energy Systems，1994，16(6),pp365-376．

[2] Henschel S，Ibrahim A I，Dommel H W．Transmission line model for variable step size simulation algorithms[J]．Electrical Power and Energy Systems，1999，21(3),pp191-198．

[3] Stankovic A M,Mattavelli P, Caliskan V, et al. Modeling and analysis of FACTS devices with dynamic phasors. IEEE Power Engineering Society Winter Meeting,2000, 2,pp1440-1446.

[4] Mattavelli P，Verghese G C，Stankovic A M．Phasor dynamics of thyristor-controlled series capacitor systems[J] ． IEEE Trans on Power Systems，1997，12(3),pp1259-1267．

[5]Aleksandar M，Stankovic¡ä，Timur Aydin．Analysis of asymmetrical faults in power systems using dynamic phasors[J]．IEEE Trans．on Power Systems，2000，15(3),pp1062-1068．

A Non-Insulated Step-Up/Down DC-DC Converter With Wide Range Conversion

ABSTRACT:

 In this paper an approach of a step-up/down dc-dc converter with wide range conversion called Boost²-Buck is presented. The proposed converter presents nonpulsating input and output current. It has operations equivalent to a cascade converter consisting of two boost converter and one buck converter, but with the advantage of using single active switch. Mathematical analysis and experimental results are presented for converter operating with output power of 20W.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

CONCLUSION:

The boost²-buck converter presented in this paper provides a wide range of dc conversion when compared with the conventional non-insulated dc-dc converters. This topology presents non pulsating input and output current. It has operations equivalent to a cascade converter consisting of two boost converter and one buck converter, but with the advantage of using single active switch. Consequently, when compared with a converter cascade, it is cheaper, less bulky and uses circuit control simpler. Through the experimental results is possible to prove the performance of the converter as well as the theoretical analysis presented.

REFERENCES:

[1] J. A. Morales-Saldaña, J. Leyva-Ramos, E. E. Carbajal-Gutiérrez, M. G. Ortiz-Lopez, “Average Current-Mode Control Scheme for a Quadratic Buck Converter with a Single Switch,” IEEE Trans. on Power Electronics, vol. 23, pp. 485–490, Jan. 2008.

[2] J. R. de Britto, A. E. Demian Jr., E. A. A. Coelho, L. C. de Freitas, V. J. Farias, J. B. Vieira Jr., “A Proposal of Led Lamp Driver for Universal Input Using Cuk Converter,” IEEE 39th Power Electronics Specialists Conference, Rhoedes, 2008.

[3] J. R. de Britto, A. E. Demian Jr., E. A. A. Coelho, L. C. de Freitas, V. J. Farias, J. B. Vieira Jr., “LED Lamp Driver Using a Converter with Wide Range Conversion Microcontroller-Based,” 34th Annual Conference of the IEEE Industrial Electronics Society (Accepted), Orlando, 2008.

[4] J. A. Morales-Saldaña, J. Leyva-Ramos, E. E. Carbajal-Gutiérrez, “Modeling of Switch-Mode DC-DC Cascade Converters,” IEEE Trans. on Aerospace and Electronic Systems, vol. 38, pp. 295–299, Jan. 2002. 

A Variable-Speed, Sensorless, Induction Motor Drive Using DC Link Measurements

A Variable-Speed, Sensorless, Induction Motor Drive

Using DC Link Measurements

ABSTRACT:

This paper presents a new control strategy for three-phase induction motor which includes independent speed & torque control loops and the current regulation thereby overcoming the limitation (i.e. sluggish response) of volts per hertz controlled industrial drives. For close-loop control, the feedback signals including the rotor speed, flux and torque are not measured directly but are estimated by means of an algorithm. The inputs to this algorithm are the reconstructed waveforms of stator currents and voltages obtained from the dc link and not measured directly on stator side. The proposed drive thus requires only one sensor in the dc link to implement the close-loop speed and torque control of a three-phase induction motor. The simulation results on a 2.2 kW induction motor drive in Matlab/Simulink software show fast dynamic response and good agreement between the actual values and the estimated values of torque and speed. Replacement of the open-loop control strategy of existing v/f drive by the proposed close-loop strategy appears to be possible without requiring any additional power components and sensors.

KEYWORDS:

1. Speed-sensorless

2. Estimation

3. Dc link

4. Band-pass filter

5. Reconstruction

6.Three-phase induction motor

7.Space-vector.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

                                              Figure 1. Block diagram of the proposed scheme.

CONCLUSION:

In this paper, a new control strategy for induction motor drive is proposed. The drive is operated under torque control with an outer speed loop and is very similar to open-loop v/f drive in terms of power components and sensors required. Due to the inclusion of torque control loop, the drive response is fast and stable. Simulation results confirm the effectiveness of the proposed scheme. The technique uses only dc link voltage and dc link current measurements to generate the estimates of the dc link voltage is assumed as constant, only one current sensor in the dc link is sufficient to give the estimates of all required feedback variables. Moreover, the same current sensor that is already available in the dc link of an open-loop v/f drive for protection purpose can be used. Thus the open loop control strategy in an existing v/f drive can be replaced by the proposed close-loop control strategy without requiring any additional power components or the physical sensors. The proposed strategy appears to be a good compromise between the high-cost, high-performance field-oriented drives and the low-cost, low-performance v/f drives. Practical implementation of the proposed scheme on a 16 bits floating point arithmetic Texas Instrument TMS320C31 processor are the subject of future follow-up research work.

REFERENCES:

[1] B. K. Bose, Power Electronics and Motor Drives, Delhi, India, Pearson Education, Inc., 2003.

[2] M. Rodic and K. Jezernik, “Speed-sensorless sliding-mode torque control of induction motor,” IEEE Trans. Ind. Electron., vol. 49, no. 1, pp. 87-95, Feb. 2002.

[3] L. Harnefors, M. Jansson, R. Ottersten, and K. Pietilainen, “Unified sensorless vector control of synchronous and induction motors,” IEEE Trans. Ind. Electron., vol. 50, no. 1, pp. 153-160, Feb. 2003.

A 24-Pulse AC–DC Converter Employing a Pulse Doubling Technique for Vector-Controlled Induction Motor Drives

A 24-Pulse AC–DC Converter Employing a Pulse Doubling Technique for Vector-Controlled Induction Motor Drives

ABSTRACT:

This paper dealswith various multipulse AC–DC converters for improving the power quality in vector-controlled induc-tion motor drives (VCIMDs) at the point of common coupling. These multipulse AC–DC converters are realized using a reduced rating autotransformer. Moreover, DC ripple reinjection is used to double the rectification pulses resulting in an effective harmonic mitigation. The proposed AC–DC converter is able to eliminate up to 21st harmonics in the supply current. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed AC–DC converter. A set of power quality indices on input AC mains and on the DC bus for a VCIMD fed from different AC–DC converters is also given to compare their performance.

KEYWORDS:

1. Autotransformer

2. Multipulse AC–DC converter

3. DC ripple reinjection

4. Pulse doubling

5. VCIMD.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1: MATLAB block diagram of proposed ac-dc converter fed VCIMD (Topology ‘D’).

Figure 2: The proposed 24-pulse ac-dc converter fed VCIMD (Topology C).

CONCLUSION:

Reducedratingautotransformer-based12-and24-pulse AC–DC converters have been designed, modelled and compared with a six-pulse AC–DC converter feeding VCIMD. DC ripple reinjection technique for pulse dou-bling has been used for harmonic reduction in VCIMD. The pulse doubling technique needs only two additional diodes along with a suitably tapped inductor. The pro-posed AC–DC converter has resulted in a reduction in the rating of the magnetics, leading to the saving in the overall cost of the drive. The proposed AC–DC converter is able to achieve close to unity PF along with a good DC link voltage regulation in the wide operating range of the drive. The proposed AC–DC converter has demonstrated its capability in improving various power quality indices at the AC mains in terms of THD of the supply current, THD of the supply voltage, PF and CF. It can easily replace the existing six-pulse converters without much alteration in the existing system layout and equipments.

REFERENCES:

1. B.K. Bose, ‘Recent advances in power electronics’,IEEETrans.onPower Electronics, Vol. 7, No. 1, Jan. 1992, pp. 2-16.

2. P. Vas, Sensorless vector and direct torque control, Oxford University Press, 1998.

3. IEEE Guide for harmonic control and reactive compensation of Static Power Converters, IEEE Std. 519-1992.

4. Hahn Jaehong, Kang Moonshik, P.N. Enjeti & I.J. Pitel, ‘Analysis and design of harmonic subtracters for three phase rectifier equipment to meet harmonic compliance’, Proc.IEEE, APEC’00, Feb. 2000, Vol. 1, pp. 211-217.

5. D.A.Paice, Power Electronic Converter Harmonics: Multipulse Methods for Clean Power, New York, IEEE Press 1996.