With the rapid development of the direct current (DC) distribution network

DC voltage measurement technology is increasingly important to ensure safe operation in the distribution network. The measurement accuracy of the traditional sensor based on resistance dividers decreases over time because the resistors age due to temperature and electromagnetic radiation. To address this problem

a novel type of medium-voltage DC voltage sensor with self-correction ability is presented in this paper. A resistor with large

$R_{\mathrm{H}}$

is connected in series with

$R_{\mathrm{K}}$

and

$R_{\mathrm{G}}$

i.e. two precise resistors with low resistance

to transform the measured medium voltage into low voltage. Among these three resistors in the divider

$R_{\mathrm{H}}$

connects with the measured medium DC line

while

$R_{\mathrm{G}}$

connects with the ground. An electronic switch

K

is paralleled with

$R_{\mathrm{K}}$

the precise resistor at the middle position. Generally

the state of the electronic switch is off

and the current flows through

$R_{\mathrm{K}}$

. Medium DC voltage can be measur

ed according to the voltage on

$R_{\mathrm{G}}$

with the divider ratio. When the sensor needs self-correction

the electronic switch will be controlled by FPGA (Field Programmable Gate Array) to turn it off and on; therefore

two values of low voltage can be obtained using time-sharing sampling. Two equations can be built according to the divider principle

and

$R_{\mathrm{H}}$

in the divider can be evaluated by solving the equations. As a result

the measurement error caused by the change in

$R_{\mathrm{H}}$

can be avoided. Finally

the medium-voltage DC sensor developed in this paper has been tested at the Institute of High Voltage

Wuhan

China. The experimental results show that the sensor can perform self-correction without manual operation

and the sensor's accuracy can reach 0.12%. Sensors with a self-calibration function can realize long-term high-precision measurement without manual maintenance

showing a good application prospect.