a smart grid application – street lighting ... - Scientific Bulletin

316 Dan Simhas, Claudiu Popovici
ΔU
ΔU [%] = ⋅100
(2)
U spl
where U spl is the actual supply phase voltage of the network.
Voltage drop formula [15] is considered:
where:
r ⋅ P + x ⋅Q
1
(3)
1 1
ΔU
p
=
U
spl
r 1 – specific resistance [Ω/m],
x 1 – inductive reactance [Ω/m],
P, Q – active and reactive phase power [kW], [kVAr].
Considering a constant power factor cos φ for every P k , Q k it can be written:
Using (4) and (3),
For the first lamp, (1) becomes:
P
Q
P
k
Q
= tgϕ
(4)
P
k
=
( r + x ⋅tgϕ)
P
U
1
(5)
1 1
Δ
p
=
U
spl
= P ⋅( K + K ⋅ ΔU
1[%])
(6)
L1 N 1 2 p
Power losses in the lamps power supply line [16] are computed:
where:
r
2 2
⋅ l ⋅ ( Ea
+ Er
)
( U ⋅T
) 2
ΔP pl – are power losses of the supply wire [kW],
0
Δ Ppl
=
(7)
spl int