When the current passes through the electrical equipment (resistance), the pressure difference between the two ends of the equipment is called the voltage drop. When the current passes through the conductor, it will experience a certain resistance, but under the action of voltage, the current can overcome this resistance and pass the conductor smoothly. The greater the resistance, the greater the change in voltage difference. Voltage drop is also called voltage difference or potential difference. The symbol is ΔU, and the unit is volt (V). It is an electrical physical quantity that describes the amount of work done by the electric field force to move the charge. The potential difference between any two points is the voltage drop between the two points.
U1 is the starting voltage and U2 is the end voltage, so the voltage drop of this section of the cable is ΔU=U1-U2. In high-voltage power transmission systems, in order to reduce line losses, the output voltage U1 of the generating unit is generally 5% to 10% higher than the nominal voltage Un of the grid to balance the line losses and keep the terminal voltage close to the nominal voltage of the grid.
Voltage drop calculation:
1. Calculate the line current I
I=P/1.732*U*cosθ
P-power (kW); U-voltage (kV); cosθ-power factor, photovoltaic output power quality is high, the power factor can be ignored, that is, cosθ=1.
2. Calculate line resistance RR=ρ*L/S
ρ-conductor resistivity (copper core cable ρ=0.01740, aluminum conductor ρ=0.0283); L-line length (m); S-nominal cross-section of the cable (Mm2)
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