OUTLINE

•BASIC BLOCK DIAGRAM OF SSSC

•DESIGN OF MULTI PULSE CONVERTER

•DESIGN OF SSSC

•CONCLUSION

Fig : Phasor diagram [2]

STATIC SYNCHRONOUS SERIES COMPENSATOR

BLOCK DIAGRAM OF MULTIPULSE CONVERTERS

Fig : BLOCK DIAGRAM OF MULTIPULSE CONVERTER [5]

6 PULSE CONVERTER

The harmonic content in 6 pulse converter is of the order 6k± 1, k= 1, 2, 3…..[9]

12 PULSE CONVERTER

The harmonic content in 12 pulse converter is of the order 12k± 1, k= 1, 2, 3….[7].

24 PULSE CONVERTER

The harmonic content in 24 pulse converter is of the order 24k± 1, k= 1, 2, 3…..[7]

48 PULSE CONVERTER

The harmonic content in 48 pulse converter is of the order 48k± 1, k= 1, 2, 3….[7].

TRANSFORMER SECONDARY AND TERITIARY WINDINGS[9]

In 48 pulse converter total of 24 single phase transformers are taken out of which

18 are 1 phase 3 winding transformers 6 are 1 phase 3 winding transformers

1st and 5th 6pulse inverters are connected to 1 phase 2 winding transformers

The turns ratio of various transformers in the magnetic circuit are as shown in the table below.

[9]

DESIGN OF SSSC

The 48 pulse converter thus designed above is connected in series with the line with the help of interfacing transformer as shown in the figure below.

[9]

The test data for simulation of SSSC using 48 pulse converter is taken from the Eigen value Analysis of IEEE first bench mark model used for the SSR analysis.

A PI controller is designed in order to vary the amount of induced voltage in to the line so that amount of power flowing through the line gets varied.

The amount of induced voltage is directly proportional to the dc capacitor voltage as shown below

Vinj =8σVan Van =2Vdc/∏ Van is line to neutral voltage of single 6-pulse converter Vab=16√3σVdc/∏

SSSC is made to operate capacitor by inducing a voltage 90 deg lagging to that of the line current

It is also operated as an inductor by making the induced voltage lead the line current by 90 deg

The simulation results of both inductive and capacitive regions are obtained

COMPARISON OF FACTS CONTROLLERS

ControllerVoltage Control

Transient Stability

Damping Power

Oscillations

Reactive Power

Compensation

Power Flow

Control

Sub synchronous Resonance (SSR)

Mitigation

Static Synchronous Series Compensator (SSSC)

Yes Yes Yes Yes Yes Yes

Thyristor Controlled Series Compensation (TCSC)

Yes Yes No Yes Yes No

Thyristor Switched Series Capacitor (TSSC)

Yes Yes No Yes Yes No

Cost Comparison of SSSC with TCSC and TSSC

In the case of TCSC and TSSC, the insulation cost, maintenance cost are high but installation cost is low.

In the case of SSSC the insulation cost, maintenance cost are low but installation cost is high because of coupling transformers and a 48-pulse VSI.

CONCLUSION

SSSC with its superior characteristics like immunity to sub synchronous resonance, power oscillation damping, quick response time, wider control range, and lower maintenance cost can be used effectively for series compensation of the Transmission line.

Thus due to above superior characteristics SSSC is going to replace all the conventional series compensators

REFERENCES

[I] Gyugyi. L, "Reactive Power Generation and Control by Thyristor Circuits," Power Electronics Specialist Conference, Cleveland, OH, June 8-10, 1976 IEEE Transactions on Industry Applications, vol IA-15, No 5, September/October 1979.

[2] Schauder, C.D. et al, "Development of a ±100 MVAR Static Condenser for Voltage Control of Transmission Systems," IEEE, PES Summer Power Meeting, Paper No 94 SM 419-6 PWRD, 1994.

[3] Zuniga-Haro, P., Ramirez, J.M., “Static synchronous series compensator operation based on 48-pulse VSC”, Proceedings of the 37th annual North American Power Symposium, 23-25 Oct. 2005.

[4] Gyugyi, L , "Dynamic Compensation of AC Transmission Lines by Solid-state Synchronous Voltage Sources," IEEE Transactions on Power Delivery, Vol 9, No 2,Apnl 1994.

[5] Gyugyi, L , et al , "The Unified Power Flow Controller A New Approach to Power Transmission Control,'' vol IO, No 2, April 1995.

[6] Ramey, D G, et al, "Use of FACTS Power Flow Controllers to Enhance Transmission Transfer Limits," Proceedings of the American power Conference, 1994.

[7] L. Gyugyi, C.D. Schauder and K.K. Sen, “Static Synchronous Series Compensator: A Solid-State Approach to the Series Compensation of Transmission Lines,” IEEE Trans. Power Delivery, Vol. 12, No. 1, pp. 406-417, 1997.

[8] K.K. Sen, “SSSC - Static Synchronous Series Compensator: Theory, Modeling and Application,” IEEE Trans.Power Delivery, Vol. 13, No. 1, pp. 241-246, 1998.

[9]Sunil Kumar, L., Arindam Ghosh.,” Modeling and control design of a static synchronous series compensator,” , IEEE Transactions Power Delivery , Volume 14, Issue 4, Oct. 1999.

[10] Narain G. Hingorani, Laszlo Gyugi, ” Understanding Facts-Concept and Technology of Flexible AC Transmission Systems”, First Indian Edition 2001.

[11] http://my.epri.com/portal/server.pt