Design, Development and Analysis of a Voltage Sensor Based on Capacitive Voltage Divider for Smart Grid Applications

With the recent push for renewable energy several former consumers units now have energy generation capabilities. While this approach is beneficial in general, it also poses new challenges for cooperation and grid stability. The new smartgrid now needs bidirectional power flow, data communication, and intelligent controls in order to ensure reliable operation. Voltage sensing plays a key role, capacitive voltage transformers have been demonstrated useful for high- voltage (100kV+), but have not yet been discussed for low (220V) and medium (13kV) voltage. This paper proposes a simplified capacitive voltage divider circuit for low-voltage measurement. Mathematical modelling is used for steady-state operation, circuit design, and sensitivity to analysis. Monte-Carlo simulations are employed to verify the effect of component tolerances, indicating under 0.7dB gain, and 0.03° error at fundamental frequency. Experimental validation is performed at low-voltage levels (127V), indicating 0.5 dB magnitude and 0.3° phase deviation at fundamental frequency. Performance is also validated from 60Hz to the 50th harmonic, showing 20° phase deviation at the higher order harmonics (16th and up). From the obtained results it is expected that the sensor is sufficient for voltage quality measurements, but should be software-corrected if power measurement is required at the high-order harmonics.

A Development of a Capacitive Voltage Divider for High Voltage Measurement as Part of a Combined Current and Voltage Sensor

This article deals with the development of capacitive voltage divider for high voltage measurements and presents a method of analysis and optimization of its parameters. This divider is a part of a combined voltage and current sensor for measurements in high voltage power networks. The sensor allows continuous monitoring of the network distribution status and performs a quick diagnosis and location of possible network failures. Deployment of these devices will support semi-autonomous control of power networks and it can be considered as a step from traditional power grids toward smart grids. This is a worldwide trend connected with increasing number of renewable energy sources and plug-in electric vehicles as described in. In this way, it contributes to the reliability of the distribution network. Together with automated control techniques and fault location methods, it enables its self-healing capability. The following characteristics required for the sensor include: current measurement error up to 2 %, voltage measurement error up to 0.5 %, and power measurement error up to 5 %. At the same time, it is necessary that the sensor is cost-effective - relatively cheap. There were selected capacitors made in series production for the capacitive divider designing. The capacitive voltage divider was tested in terms of time and temperature stability; the results are described in the paper. Then, the method of mathematical correction of a temperature dependence of the capacitive voltage divider was suggested and tested.