Power stability analysis to PV &QV curves ,CPF power analysis , Kundur and Pai book to refer them

1. INTERPRET VOLTAGE INSTABILITY & COLLAPSE
USING DIFFERENT VOLTAGE STABILITY INDICIES,
P-V& Q-V CURVES AND CONTINUATION POWER
FLOW TECNIQUE
NAME: BOSAMIYA KRISHNA
GUIDE NAME: PROF. VIREN PANDYA
DEPARTMENT OF ELECTRICAL ENGINEERING
SHANTILAL SHAH ENGINEERING COLLEGE, BHAVNAGAR
GUJARAT TECHNOLOGICAL UNIVERSITY

2. OUTLINE
 Introduction
 Classification of voltage stability
 General Characterization based on actual incidents voltage
collapse
 Prevention of voltage collapse
 Classification of voltage stability indices (VSI)
 Using Different voltage stability indices (VSI)
 Flowchart of calculation procedure of VSI
 Explain Static analysis PV & QV curves
 Simulation of PV & QV curves
 Principle, mathematical, steps, Application of Continuation
power flow analysis
 Conclusion
 References

3. INTRODUCTION
 Voltage stability refers to the ability of a power system to maintain
steady voltages at all buses in the system after being subjected to a
disturbance from a given initial operating condition.
 Large-disturbance voltage stability refers to the system’s ability to
maintain steady voltages following large disturbances such as
system faults, loss of generation, or circuit contingencies
 Small-disturbance voltage stability refers to the system’s ability to
maintain steady voltages when subjected to small perturbations
such as incremental changes in system load.
 Short-term voltage stability involves dynamics of fast acting load
components such as induction motors, electronically controlled
loads, and HVDC converters.
 Long-term voltage stability involves slower acting equipment such as
tap-changing transformers, thermostatically controlled loads, and
generator current limiters.

4. CLASSIFICATION OF VOLTAGE STABILITY

5. GENERAL CHARACTERIZATION BASED ON
ACTUAL INCIDENTS VOTAGE COLLAPSE

6. PREVENTION OF VOLTAGE COLLAPSE
 Application of reactive power-compensating
devices
 Control of network voltage and generator reactive
output
 Coordination of protection/controls
 Control of transformer tap changers
 Under voltage load shedding

7. CLASSIFICTAON OF VOLTAGE STABILITY
INDICES(VSI)

8. USING DIFFERENT VOLTAGE STABILITY
INDICES(VSI)
 Classification
◦ Jacobian matrix and system variables based VSIs
◦ Bus, line and overall VSIs
 Jacobian matrix and system variables based VSIs
◦ Calculates voltage collapse point
◦ Time consuming
◦ No real-time VS assessment
 Line VS indices
◦ Based on two bus system
◦ Shunt admittances are neglected
 Fast voltage stability index (FVSI)

9.  Fast voltage stability index (FVSI)

11. FLOWCHART OF CALCULATION PROCEDURE OF
VSI

12. EXPLAIN STATIC ANALYSIS PV & QV CURVES

15. QV CURVES
 The V-Q curve method is one of the most popular
ways to investigate voltage instability problems in
power systems during the post transient period.
 Voltage at a test bus or critical bus is plotted against
reactive power at that bus.
 A fictitious synchronous generator with zero active
power and no reactive power limit is connected to the
test bus.
 The power-flow program is run for a range of
specified voltages with the test bus treated as the
generator bus.
 Reactive power at the bus is noted from the power
flow solutions and plotted against the specified
voltage.

16.  The operating point corresponding to zero reactive
power represents the condition when the fictitious
reactive power source is removed from the test
bus.
 For the simple two-bus system, equations of V-Q
curves for constant power loads can be derived
from PV curve study done previously.

17. SIMULATION OF PV & QV CURVES

18. PRINCIPLE OF CONTINUATION POWER FLOW
ANALYSIS
 The continuation power-flow analysis uses an
iterative process involving predictor and corrector
steps as depicted in fig.
 From a known initial solution (A), a tangent predictor
is used to estimate the solution (B), for a specified
pattern of load increase. The corrector step then
determine the exact solution (c) using a
conventional power-flow analysis with the system
load assumed to be fixed.

19.  The voltages for a further increase in load are then
predicted based on a new tangent predictor. If the
new estimated load (D) is now beyond the maximum
load on the exact solution a corrector step with loads
fixed would not converge therefore a corrector step
with a fixed voltage at the monitored bus is applied
to find the exact solution (E).

22. SELECTION OF CONTINUATION PARAMETER
 Sensitivity information
 Complementary use of conventional and
continuation methods
 Illustration of continuation power flow analysis

23. CONCLUSION
The same voltage expression is used to draw P-V
curve of a radial transmission line. It is observed that real
power transfer increases from lagging to leading power factor.
Using the Q-V curves the sensitivity of the load to the reactive
power sources can be obtained. The shown simulations
indicate that the bus 14 of IEEE 14 bus bar test system is
considered the weakest bus in the system. Line indices
provide an accurate information with regard to the stability
condition of the lines. The research shows an agreement
between the different line stability indices.

24. REFERENCES
1) Book power stability and control by p. kundur, pai
, mc graw-hill ,1994
2) A comparison of voltage stability indices claudia
reis, F.P maciel barbosa
IEEE research paper ,may 2006 ,Spain.
3) PV & QV curves a novel approach for voltage
stability analysis snehal B. Bhaladhare ,
A.S.Telang ,prashant P.Bedkar ncipet -2013
4) Voltage stability indices taxonomy, formulation
and calculation algorithm
research gate ,January 2016 ,Ebrahim Sadati