# Simulation of Libe Outage

## Simulation of Libe Outage

CHAPTER 3

SIMULATION OF LINE OUTAGE

3.1 Linearised expressions for Real And Reactive Power Flow Changes In Transmission Line

3.1.1 Line outage

In a power system, when the transmission line between any two bus bars is opened, then it is known as line outage.

Let, the transmission line between two bus-bars(let, the bus numbers be Kth and Mth ) is opened. This is known as line outage between the bus-bars. Then no power transmission takes place between the bus-bars. It means, it will not take any power from the power system.

Let, the outage line ‘j’ is assumed to be connected between Kth & Mth buses. When the line is not opened, then real and reactive power flows take place in the transmission line.

3.1.2 Linearised expression for real &reactive power flows

The real and reactive power flows in a transmission line connecting buses k and m are given by,

pkm = gjvk2- gjvkvm cosδkm + bjvkvm sinδkm (3.1)

pmk = gjvm2- gjvkvm cosδkm - bjvkvm sinδkm (3.2)

qkm = bjvk2 - bjvkvm cos δkm - gjvkvm sinδkm (3.3)

qmk = bjvm2- bjvkvm cos δkm + gjvkvm sinδkm (3.4)

Where pkm : real power flow from kth bus to mth bus.

qkm : reactive power flow from kth bus to mth bus.

pmk : real power flow from mth bus to kth bus.

qmk : reactive power flow from mth bus to kth bus.

vk and vm : are the bus voltages at kth bus to mth bus.

δkm : phase angle between at kth bus to mth bus.

where

gj = rj/(rj2+xj2) and bj =xj/(rj2+xj2)

rj : resistance of jth transmission line connected between kth and mth buses.

xj : reactance of jth transmission line connected between kth and mth buses.

bji = bj- bsh,j

bsh,j = Half of the line charging susceptance of jth...