Voltage Regulation Method for Voltage Drop Compensation and Unbalance Reduction in Bipolar Low-Voltage DC Distribution System

Abstract

Owing to the development of highly efficient electric power converters, the number of studies on the construction of low-voltage dc (LVDC) systems is gradually increasing. To use LVDC distribution systems, voltage regulation methods to compensate for the voltage drop and to limit the voltage unbalance are essential. In a bipolar LVDC distribution system, a voltage drop and voltage unbalance could occur because of the load current and the variation in the amount of power supplied to the poles. However, not enough research has been conducted on voltage regulation methods for LVDC distribution systems. To reduce the voltage drop and the voltage unbalance, this paper proposes a voltage regulation method based on the neutral to line drop compensation (NLDC) method, which employs a modified LDC to calculate the sending-end reference voltage. In the NLDC method, the neutral current and neutral line impedance are taken into consideration to compensate for the neutral line potential fluctuation and voltage drop on the pole. The next sending-end voltage is determined by checking the voltage unbalance factor, and it is adjusted to maintain it within the allowable voltage unbalance factor. A voltage regulation algorithm and a bipolar LVDC system model are implemented using the Electromagnetic Transients Program.