Bipolar Hvdc Transmission System Study: Development of Controlled Cascade Rectifier for Insulator Testing. Final Report

摘要

This project constitutes a continuation of EPRI project 430-1 covering the power supply for insulator pollution testing. The aims of this project are to determine the circuit elements of a controlled cascade rectifier source to perform pollution tests; the effect of the voltage drop and the short-circuit current on the 50% flashover voltage; the reduction of the 50% flashover voltage with increasing pollution severity on insulators; the effect of the dc resistance R/sub dc/ on the 50% flashover voltage; and to study the leakage current behavior during artificial-pollution tests. The circuit elements of a controlled cascade rectifier source were determined on a model circuit and the results were generalized with a computer program. The proper operation of the circuit was verified with a full-scale circuit at 100 kV. The circuit elements of this controlled source were optimized with respect to the estimated total cost of the power supply. Among the major conclusions of the study are the following: a controlled cascade rectifier connected in a voltage doubler arrangement is an adequate power supply for testing insulators under heavy pollution; and the specifications of the hvdc power supply sufficient to determine the 50% flashover voltage of heavily contaminated insulators (ESDD = 0.5 mg/cm exp 2 ) within an accuracy of 5% may be expressed as the power supply should have a voltage drop of less than 5% at the highest current of 2 A, and the short-circuit current at the output of the hvdc source should be higher than 10 A. This refers to the quasi-stationary short-circuit current subsequent to the transient discharge of the smoothing capacitor. (ERA citation 05:033609)