POWER SYSTEM STABILIZER

SUMAN SOURABHB.TECH EEE,FINAL YEAR06570104910

Power System Stability

Power system stability is the ability of an electric power system, for a given initial operating condition, to regain a state of operating equilibrium after being subjected to a physical disturbance, with most system variables bounded so that practically the entire system remains intact.

Stability Classification

POWER SYSTEM STABILIZERS

• PSS are generator control equipments which are used in feed back to enhance the damping of rotor oscillation caused due to small signal disturbance.

• This disturbance may be caused by the even small change in the reference voltage of the automatic voltage regulator/exciter which results in ever increasing rotor oscillations.

• This is achieved by modulating the generator excitation so as to develop components of electrical torque in phase with rotor speed deviations. The PSS thus contributes to the enhancement of small-signal stability of power systems.

Contd...........

Types

A. Speed-Based (Δω) StabilizerB. Frequency-Based (Δf) StabilizerC. Power-Based (ΔP) Stabilizer

WORKING

• under some conditions, such as much impedance, heavy load need etc., the additional torque ΔMe2 provided by the AVR lags the negative feedback voltage by some angle.

• The power system stabilizer, using the speed signal (Δ ω) as input signal, will have a positive damping torque component ΔMp2.

• So, the synthesis torque with positive synchronous torque and the damping torque can enhance the capacity of the damping

oscillation.

The system diagram of power system stabilizer(PSS)

Functional block diagram of PSS

ADVANTAGES & DISADVANTAGES

• Improved damping of the system• The dynamic stability of a system is improved.• Reduced power losses.• Time consuming tuning of PSS.• Non-optimal damping in the entire operating

range.  

REFRENCES

1. Kunder, P. (1994). Power System Stability and Control, McGraw-Hill.2. Anderson, P. M.; & Fouad, A. A. (2003). Power System Control and Stability(Second

Edition),John Wiley & Sons.3. Zhang, X.P.; Rehtanz, C.; & Pal, B.(2006). Flexible AC Transmission Systems:

Modeling and Control.4. Study on Oscillation Damping Effects of Power,System Stabilizer with Eigenvalue

Analysis Method for the Stability of Power Systems,Fang Liu1, Ryuichi Yokoyama, Yicheng Zhou, Min Wu,Waseda University,Japan.

5. www.google.com6. www.bing.com7. www.wikipaedia.com

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