Thyristor valve is widely used in LCC-HVDC

SVC

DC-based deicing etc. The performance of Thyristorvalve is significant to the normal operation of the project. Between installation and commissioning

or after the re-placement of thyristor-level components

functional test must be carried out on the thyristor levels to check its volt-age

current and optical signal under a variety of operation conditions

and to judge whether all functions and perfor-mance are normal. During site test the normal operation fiber connected between TCU and VBE must be changed totest fiber which is connected between TCU and tester in order to trigger thyristor. When finished

optical fiber mustbe changed back. Repeated plug-pull may cause contamination and damage to optical fiber and other optical devic-es

and it can’t be determined whether the function is normal after reinsertion

finally decrease system reliability.Therefore

it is necessary to design a thyristor valve functional test system for the site test. All tests of thyristor level

including impedance

firing

protection

withstand voltage strength and other items

can be carried out without mov-ing any connected fibers. Based on coordination of the function and timing sequence between the tester and VBE

thetester

thyristor valve and VBE are combined to form a functional test system. During test

there is only electricalconnection between the thyristor level and the tester. A whole testing of electrical signals and optical signals can beachieved efficiently and reliably.