Electrotechnical Systems

11Special Features of SimPowerSystems™ Models

After substitution in (1.5) and taking into account (1.6) through (1.9), it follows for

each node (bus):

PP yVV

gi li ij

j

n

ij ii

jj

=+ −−

=

∑

1

cos( )δ

γδ

(1.12)

QQ yVV

gi li ij

j

n

ij ii

jj

=+ −−

=

∑

1

sin( )δ

γδ

(1.13)

The load powers P

li

, Q

li

are supposed to be known. Thus, for each node, there are two

equations with four unknown quantities: P

gi

, Q

gi

, V

i

, δ

i

; therefore, two quantities have

to be assigned, but deciding which one to use will depend on the bus type. Three

possible types exist: (1) The reference bus in SimPowerSystems called “Swing bus”;

in this node (bus), it is accepted V

i

= 1 δ

i

= 0, for unknown quantities P

gi

, Q

gi

. Only

one such node can exist in the system. Usually, it is the generator of the ...