Determination of loss and capacity on a 110kV line made of ACO-120 conductor 85km long, 15MVA load, power factor 0.85, maximum usage time 5200h.
The first step in determining the loss and capacity of the line is to calculate the resistance and reactance per unit length of the ACO-120 conductor. According to industry standards, ACO-120 has a resistance of 0.2070 ohms/km and a reactance of 0.157 ohms/km at a frequency of 50 Hz. Therefore, the resistance and reactance per unit length of the 110kV line made of ACO-120 conductor (85km long) is:
Resistance per unit length = 0.2070 ohms/km x 85 km = 17.595 ohms
Reactance per unit length = 0.157 ohms/km x 85 km = 13.345 ohms
To calculate the loss on the line, we will use the formula:
Ploss = I^2 x R
where Ploss is the power loss, I is the line current, and R is the resistance per unit length. The maximum usage time of 5200h is the annual operating time (i.e. full load running hours per year). Therefore, the daily operation time is:
Tdaily = 5200h / 365 = 14.25h
The line current can be calculated using the formula:
I = P / (sqrt(3) x V x PF)
where P is the power demand, V is the line voltage, and PF is the power factor. Therefore, the line current with a load of 15MVA, power factor of 0.85, and voltage of 110kV is:
I = 15,000,000 / (sqrt(3) x 110,000 x 0.85) = 98.58 A
Now we can calculate the power loss on the 110kV line:
Ploss = I^2 x R x Tdaily
= (98.58 A)^2 x 17.595 ohms x 14.25 h
= 40,474.12 kWh
To determine the capacity of the line, we will use the formula:
S = V^2 / (sqrt(3) x Z)
where S is the apparent power capacity, V is the line voltage, and Z is the impedance per unit length (Z = sqrt(R^2 + X^2)). Therefore, the impedance per unit length of the 110kV line made of ACO-120 conductor is:
Z = sqrt(17.595 ohms^2 + 13.345 ohms^2) = 22.065 ohms/km
The apparent power capacity of the line is:
S = 110,000^2 / (sqrt(3) x 22.065 ohms) = 1,126.8 MVA
Therefore, the 110kV line made of ACO-120 conductor with a length of 85km can carry a maximum load of 1,126.8 MVA and will incur a power loss of 40,474.12 kWh with a 15MVA load and power factor of 0.85, over a maximum usage time of 5200h.