Patrick P. Chavez

230 kV Optical Voltage Transducers Using Multiple Electric Field Sensors

230 kV optical voltage transducers were constructed and tested. These transducers use three electric field sensors whose positions and outputs are selected and combined, respectively, in accordance with the quadrature method to obtain a voltage measurement. They meet IEC 0.2% class specifications and maintain 0.2% class accuracies even in the presence of electric field disturbances caused by local changes in geometry extemal to the transducer. The local changes in geometry used in the testing mimic those that may occur in a substation, e.g., installation or movement of equipment.

Accurate voltage measurement by the quadrature method

This paper introduces the quadrature method for measuring voltage using one or more electric field sensors. To date, all high-voltage sensors, from conventional inductive transformers to modern optical voltage transducers, have one or more of the following traits in common: large size and weight, high-voltage electrodes in close proximity, expensive and potentially hazardous insulation, and capacitive voltage division. Combined with the use of small electro-optic field sensors, the quadrature method enables voltage sensor designs that are free of these traits and that are, therefore, particularly ideal for high-voltage applications. It also allows for a trade-off between the accuracy of the voltage measurement and the number of required electric field sensors. Numerical simulations demonstrate the effectiveness of this technique.

138 kV and 345 kV wide-band SF/sub 6/-free optical voltage transducers

This paper describes the design and testing of novel, environmentally friendly, 138 kV and 345 kV optical voltage transducers (OVTs) for metering and protection relaying applications in high-voltage electric power transmission systems. Each OVT uses three miniature optical electric field sensors housed inside a resistive shield. The locations of the electric field sensors, the electrical and geometrical parameters of the resistive shield, and the formula for deriving voltage from the electric field measurements are all chosen using the quadrature method to achieve very accurate voltage measurements. The resistive shield is, in turn, housed inside a hollow composite insulator filled with low-pressure dry nitrogen. Conventional accuracy and dielectric withstand tests demonstrate that the OVTs meet IEC 60044-7 0.2 and IEEE/ANSI C57.13 0.3 accuracy class standards and insulation requirements. Further tests demonstrate their wide bandwidth (>40 kHz) and show that they successfully reject the effects of the severest possible electric field disturbances on the voltage measurement.

Wide-band 138 kV distributed-sensor optical voltage transducer: study of accuracy under pollution and other field disturbances

A 138 kV optical voltage transducer (VT) using shielded distributed electric field sensors is presented for use in high-voltage (HV) electric power transmission systems. Since HV and ground are kept far apart, the VT does not require oil or SF/sub 6/ for insulation; instead, it uses the environmentally friendly dry nitrogen as an insulating gas. A prototype has been tested for accuracy under various severe field disturbances including the presence of conductive pollution-like layers on the insulator and the presence of other HV sources nearby. The test results show that the VT meets IEC 0.2% and IEEE 0.3% accuracy classes under these extreme field disturbances. Data that demonstrates wide bandwidth of the VT are also presented. Another prototype has been tested and has successfully passed standard IEC HV dielectric withstand tests including power frequency withstand at 275 kV, partial discharge <5 pC, lightning impulse tests (BIL) at /spl plusmn/650 kV, and chopped impulse tests at -750 kV.

Integrated-optic voltage transducer for high-voltage applications

This paper describes a novel voltage transducer. Its design is based on a mathematical procedure that enables a small number of strategically positioned electric field sensors to accurately measure the voltage. The voltage transducer takes advantage of existing compact, non-intrusive optical electric field sensor technology, specifically, the integrated-optic Pockels cell (IOPC), but is not limited to optical technology. The key advantage of this voltage transducer over other existing optics-based voltage transducer technologies is that it does not require any customized electrode structures and/or special insulation. A highvoltage integrated-optic voltage transducer has been used to obtain measurements with metering class accuracies.

Resistively shielded optical voltage transducer

A high-voltage (HV) optical voltage transducer (OVT) using resistively shielded electric field sensors is presented for use in HV transmission systems. The OVT is built in a hollow-core polymer insulator filled with low-pressure dry nitrogen gas. A 138 kV prototype has been tested for accuracy under various severe dynamic field disturbances including salt-clay pollution (clean fog test) and melting ice on the insulator. The test results show that the OVT meets ANSI/IEEE 0.3 % accuracy classes under these extreme field disturbances. The prototype has also been tested and successfully passed various HV dielectric tests including lightning impulse tests (BIL) at /spl plusmn/650 kV, chopped impulse tests at -750 kV, power frequency withstand at 275 kV, and partial discharge <5 pC.