Voltage regulation
![Short line approximation. Here the line impedance Z = R + jL.](/Images/godic/202502/20/Short_Line_Approximation4301.png")
![Voltage phasor diagrams for a short transmission line serving lagging, in-phase, and leading loads.](/Images/godic/202502/20/Short_line_voltage_phasor_diagrams4301.png")
![Typical voltage profile expected on a distribution feeder with no DG. This voltage profile results from the fact that current through feeders with no DG decreases with distance from the substation.](/Images/godic/202502/20/Feeder_voltage_profile4301.png")
![Comparison of 24-hour voltage swings on a feeder with no PV, 20% PV and 20% PV with volt-VAR control.](/Images/godic/202502/20/Feeder_Voltage_Response_with_Advanced_VAR_Control4301.png")
In electrical engineering, particularly power engineering, voltage regulation is a measure of change in the voltage magnitude between the sending and receiving end of a component, such as a transmission or distribution line. Voltage regulation describes the ability of a system to provide near constant voltage over a wide range of load conditions. The term may refer to a passive property that results in more or less voltage drop under various load conditions, or to the active intervention with devices for the specific purpose of adjusting voltage.