A wideband signal conditioning system for high voltage measurements using a transconductance topology

[摘要] ENGLISH ABSTRACT:Recent research has shown that standard substation capacitive voltage transformers(CVTs) and current transformers (CTs) can be used for the measurement of wideband highvoltage phenomena by employing these apparatus in a transconductance topology. Withthis topology the voltage waveform can be obtained by integration of the ground returncurrent in the earth straps of the CVT and the CT. This technique does, however, imposeunique requirements on the amplification and integration instrumentation due to largedynamic range requirements and the strict offset specifications required for accurateintegration.This thesis describes a programmable, wideband signal conditioning system for highvoltage (HV) measurements using the transconductance topology. A suitable systemtopology, optimised to reduce the problems usually associated with grounding andelectromagnetic interference (EMI) in HV environments, is proposed. This systemconsists of an analog signal conditioning subsystem, a digital signal conditioningsubsystem and a high speed serial fibre-optic link.The analog signal conditioning subsystem conditions the signals from a sensor to levelssuitable for the digitiser of the digital signal conditioning subsystem. The high bandwidthspecification of the application made it necessary to consider both discrete and integratedimplementation of the analog signal conditioning subsystem. Based on the simulated andlaboratory test results of both implementations, the optimum design was chosen for thedeveloped system. The digital signal conditioning subsystem, which performs theintegration, as well as the serial optic-fibre link control logic was implemented usingprogrammable logic array (PLA) technology. The digital data is transmitted across thefibre-optic link. This data is then converted back to an analog signal.Keywords: High voltage measurements, Transconductance topology.

[发布机构] Stellenbosch University