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Table 1 A comparison of concepts on voltage stability indices

From: Micro-synchrophasor based special protection scheme for distribution system automation in a smart city

Reference

Concept

Assumption

[34]

Two bus system considered, discriminant of the voltage quadratic equation ≥0.

Shunt admittance is neglected.

[35]

Two bus system considered, discriminant of the voltage quadratic equation ≥0.

Shunt admittance is neglected. The angular separation of sending and receiving end bus voltage δ≈0.

[36]

Same concept as above line voltage stability indices.

Line resistance & shunt admittance neglected.

[37]

Same concept as above line voltage stability indices.

Shunt admittance is neglected. The angular separation of sending and receiving end bus voltage δ≈0.

[38]

Limiting the maximum power transferable through a transmission line.

Shunt admittance is neglected. Power factor assumed to be constant.

[39]

The voltage drop across equivalent Thevenin impedance = load voltage at the point of voltage collapse

Equivalent Thevenin impedance connected to sending bus is neglected. Ideal voltage source assumed at sending end bus.

[40]

Discriminant of the voltage quadratic equation ≥0.

Shunt admittance is neglected. Voltage angle assumed to be very small.

[41]

The largest value of difference in voltage magnitude of two buses is the correction factor β.

The voltage of the generator closest to the load bus is taken as the Thevenin voltage of the load bus.

[42]

Based on % diversity, between moving average value, RMS of N PMU values of load bus voltage, Vi and ith sampled data

The generator voltages are held constant.

Present work

An equivalent system of the local network is modeled with an equivalent source and impedance encompassing the effect of entire power system network external to the node under consideration

Angular separation of sending and receiving end bus voltage θqn is considered as it carries important information regarding system dynamics. Local synchrophasor data utilized.