Research On Electric Field Sensing Technology For Safety Early Warning Of HVDC Transmission

With its unique advantages,HVDC transmission technology has been widely used in China’s power grid.In order to ensure the safe production and application of HVDC transmission systems,electric power operators are required to regularly maintain and repair HVDC equipment.Taking DC power transmission lines and DC converter stations as an example,due to the tedious work procedures and complex environment,electric power workers are prone to approach high-voltage danger sources accidentally.It results in personal injury or death due to electric shock.By means of technical means,non-contact intelligent perception of danger sources around the operator realized.Then an alarm issued in advance to remind the operator to stay away from a safe distance.It is of great significance to ensure the safety of workers’ lives and the stable operation of DC equipment.At present,domestic and foreign power operation safety early warning technology is mainly used in the field of power frequency,but the related research on DC power transmission safety early warning technology is still relatively small.Because the high-voltage DC electric field is more difficult to detect than the power-frequency electric field.Both the acquisition and analysis of weak signals in the DC electric field and the anti-interference technology have great challenges.Taking into account the complexity of the work site environment,for different voltage levels of HVDC equipment,electric field strength measurement,multiple application scenarios and adaptive active alarm functions.This paper proposes a non-contact DC electric field sensor with safety warning function.Firstly,the finite element analysis method used to obtain the surrounding electric field distribution curves and electric field distribution curves of ± 500 k V,± 800 k V HVDC transmission lines and pipeline buses of ± 500 k V converter stations.Studing the spatial electric field distribution and change of DC charged equipment,which lays a theoretical foundation for the design of DC electric field measurement technologyand voltage level identification algorithm.Secondly,the core component of the DC electric field sensing unit,its practicability and reliability are crucial.Optimize the design of the structure of the DC electric field sensing unit,and optimize the structural parameters of the electric field sensing unit under the constraints of ensuring the sensitivity and edge effect of the sensor.Through the calibration experiment test of the electric field sensor,the static index parameters such as sensor range and sensitivity obtained to meet the needs of on-site measurement.This paper also analyzes and discusses the influence on the electric field measurement results from the sensor’s own structure and natural environmental factors.Finally,the electric field sensor was tested on-site at a ±500k V DC converter station and a HVDC transmission line simulation experiment platform;the accuracy of the electric field sensor measurement results and the reliability of the safety warning function at different voltage levels were verified.