Non‐intrusive voltage measurement of ac power lines for smart grid system based on electric field energy harvesting

A new non‐intrusive ac voltage measurement technique based on stray electric filed energy harvesting is presented whereby the voltage of ac power lines can be measured without removing insulation and therefore without direct contact with conductors of the power lines. The energy of electric field around the power lines is picked up and stored in a capacitor by a wire wound around insulated 3‐wire household power lines or by a conductor plate placed in the vicinity of overhead high‐voltage power lines. Autonomous switches are used to monitor the stored electric field energy in a storage capacitor and to generate pulse train. Experimental results show that the repetition rate of the output pulse is a linear function of the line voltage. Since the voltage of insulated 3‐wire household power line can be measured without removing insulation and the voltage of high‐voltage power transmission line can be measured without any contact to the conductor of the power line, the proposed technique can be widely applied to smart grid system.