**TRANSIENT STABILITY ANALYSIS OF MULTIMACHINE POWER SYSTEMS**

**AIM:**

(i) To become familiar with modelling aspects of synchronous machines and network for

transient stability analysis of multi-machine power systems.

(ii) To become familiar with the state-of-the-art algorithm for simplified transient stability

simulation involving only classical machine models for synchronous machines.

(iii) To understand system behaviour when subjected to large disturbances in the presence of

synchronous machine controllers.

(iv) To become proficient in the usage of the software to tackle real life problems

encountered in the areas of power system planning and operation.

# OBJECTIVES

(i) To assess the transient stability of a multimachine power system when subjected to a

common disturbance sequence: fault application on a transmission line followed by fault

removal and line opening.

(ii) To determine the critical clearing time.

(iii) To observe system response and understand its behaviour during a full load rejection at a

substation with and without controllers.

(iv) To observe system response and understand its behaviour during loss of a major

generating station.

(v) To understand machine and system behaviour during loss of excitation.

(vi) To study the effect of load relief provided by under frequency load shedding scheme.

**SOFTWARE REQUIRED**

MULTIMACHINE TRANSIENT STABILITY module of AU Power lab or equivalent

**EXERCISES**

1.. Transient stability analysis of a 9-bus, 3-machine, 60 Hz power system with the following system modelling requirements:

i. Classical model for all synchronous machines, models for excitation and speed

governing systems not included.

(a) Simulate a three-phase fault at the end of the line from bus 5 to bus 7 near bus 7 at time = 0.0 sec. Assume that the fault is cleared successfully by opening the line 5-7 after 5 cycles

( 0.083 sec) . Observe the system for 2.0 seconds

(b) Obtain the following time domain plots:

- Relative angles of machines 2 and 3 with respect to machine 1

- Angular speed deviations of machines 1, 2 and 3 from synchronous speed

- Active power variation of machines 1, 2 and 3.

(c) Determine the critical clearing time by progressively increasing the fault clearing

time.

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