Analysis of Transient stability using power world simulator

1. Bahir Dar University Institute of Technology
Faculty of Electrical and Computer
Engineering
MSC Program in Power System Engineering
Power System Dynamics and Transients Paper Presentation
On Analysis of Transient Stability Using Power World Simulator
Prepared By: Evaluated By:
Minale Birlie Dr. Ing. Belachew B.
6/26/2020
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2. Out lines:
 Introduction
 Power system stability
 Classification of power system stability
 Analysis of transient stability
 Results and discussion
 Conclusion
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3. Introduction:
 Now-a-days it has become a necessity to maintain synchronism because
the system is expanding day-to-day and these results in the installation of
larger machines.
 Due to this, transient disturbances are increasing continuously in power
system.
 A transient stability is concerned with the ability of the power system to
maintain synchronism when subjected to a severe disturbance.
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4. Cont….
 For transient stability analysis we need consider three systems
1. Prefault: System is assumed to be at an equilibrium point.
2. During fault: The fault changes the system away from its
equilibrium point.
3. Post fault: System is returned in to a new operating point
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5. Causes of Transient Stability:
 Sudden change in load demand
 Switching operation
 Generation failure
 Transmission failure
 Analysis of transient stability is required to reduce problems such as
 Blackouts,
 Loss of synchronism.
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6. Power system stability:
 Power system stability is the property of power system that
enables it to remains in a state of equilibrium under normal
condition and to regain equilibrium after being subjected to
disturbances.
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7. Classification of power system stability:
 Based on the nature of the instability mode power system stability
can be classified in to three broad categories.
a. Rotor angle stability
b. Voltage stability
c. Frequency stability
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8. Rotor angle stability:
 In general, the rotor angle stability problems are classified into three types:
 Steady-state stability: the generator falls out of synchronism as a result of
a small transient phenomenon on the network
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9. Cont..
 Transient stability: is lost as a result of a fault on the network; the
generator accelerates (speeds up) after the loss of synchronism.
 Dynamic stability: is lost as a result of sustained power angle
oscillations caused by a fault.
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10. Instability:
 Instability is a periodic drift due to insufficient synchronizing torque and
is refer to as first swing stability.
 Transient stability analysis is performed with the help of three phase
balance fault.
 Causes of three phase fault
 Lightning
 Insulation deterioration
 Wind damage
 Trees falling across lines 6/26/2020 10

11. Cont.…
 The transient and steady-state disturbance occur in power system are
shown in the graph below.
 The single line diagram of IEEE 9 bus model is shown in the figure.
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12. Power Flow Studies
 In power flow study the magnitudes and phase angles of bus
voltages, real and reactive powers on transmission lines, real and
reactive powers at generator buses, other variables being
specified.
 The pre-fault conditions can be obtained from results of load flow
studies by the Newton-Raphson iteration method.
 The Newton-Raphson method is the practical method of load
flow solution of large power networks.
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13. Result and Discussion:
 Steps for transient stability analysis using power world simulator:
 Step 1: An IEEE- 9 bus system is taken.
 Step 2: System model is implemented, excuted and load flow is
performed
 Step 3: After load flow, the initial parameters of the system are studied.
 Step 4: A three-phase balanced fault is applied on transmission line with
different clearing times and the results are taken in Power World
Simulator.
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14. Simulation Result:
 Graph of power angle and frequency vs time at normal operation
Gen.Rotorangle
Time
Time
Busfrequency
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15. Cont.…
 Graph of power angle and frequency vs time when load is increased
Busfrequency
Time
Time
Gen.Rotorangle
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16. Cont…
 Graph of power angle and frequency vs time when load is decreased
Gen.Rotorangle
Time
Time
Busfrequency
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17. Conclusion:
 It is concluded that power system should have very low critical clearing
time to operate the relays if we isolate the faulty section within very short
time.
 Thus the system can obtain the stability otherwise, and it will go out of
synchronism.
 The behavior of three-phase balanced fault and impact of load switching
is also investigated.
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