Adaptive Safety Early Warning Device for Non-contact Measurement of HVDC Electric Field

In order to prevent electric shock accidents during the maintenance and repair of high-voltage direct current (DC) live equipment, an intelligent safety early warning system device based on non-contact electric field measurement is developed in this paper, to ensure the life safety of electrical workers and the stable operation of equipment. Firstly, the self-developed electric field sensor is used to measure the electric field strength of the space around the charged device. The STM32 microprocessor in the sensor will compare the measured electric field value with a preset safety threshold. If the safety threshold is exceeded, the early warning device issues an audible alarm. It prompts the electric power operator to exit to a safe distance. In addition, the alarm prompt symbol and the real-time waveform of the measured electric field can be seen intuitively on the mobile smart APP interface. Secondly, for devices with different voltage levels, the sensor electric field measurement range and sensitivity can be dynamically adjusted by changing the motor speed. In addition, according to the voltage level identification algorithm, this is also to achieve an adaptive safety early warning of different live equipment. Finally, field experiments were performed at a ±500 kV DC converter station and an ±800 kV DC transmission line experimental platform. The measured values of the electric field are basically consistent with the simulated values, and the safety early warning device has no false positives or false negatives during the test. The experimental results show that the design of the safety warning device in this paper meets the actual needs, and it can alert the electric workers to the specified safety distance.