Contactless Voltage Distortion Measurement Using Electric Field Sensors

The measurement of harmonic voltage distortions in medium and high voltage systems is always regarded as a challenging task. For transmission systems, the widely used capacitor voltage transformers offer inadequate frequency responses for harmonic measurement. For distribution systems, voltage transformers are only available in limited locations. In order to provide a convenient and efficient solution for the situations above, this paper proposes a contactless method to measure voltage distortions. A small number of electric field sensors are used with partial knowledge of conductor geometry information of overhead lines. In addition, the method focuses on estimating the percentage harmonic voltage levels instead of the actual harmonic voltage values, which leads to a robust and simple measurement scheme. The proposed method has been validated by numerical simulations and experimental tests on a reduced scale model of an overhead transmission line.