State estimation technique obtained from CCVT transient studies

CCVT (coupling capacitor voltage transformer)
电容式电压互感器
is widely used in Electric Power Industries.
due to its complex structure and operation principle, the transient characteristics have attracted attention from all over the world to study what is affecting the transfer functions.
among the past research, serveral famous methods are undertaken:
a) off-line or lab test by applying operation voltage to the primary to simulate working conditions.
b) online measurement from the secondary.
c) off-line or lab test from the secondary, take advantage of parameter identification.

IEEETM has been conducting research and experiment parameter studies in order to obtain accurate parameter of transfer function, which will be used for online fault forcast.
Also in order to make the project feasible, online monitoring has to combine with offline data in order to adjust internal parameter by iteration techniques, as a way to analyze transfer characteristics.

Traditionally, there is much cost to test a CCVT by offline test, as it requires a standard transformer and high voltage power source, there may be some portable way of testing the CCVT which also guarantee the test accuracy.

So, a possible way is to apply test signal from the secondary, in reference with a mathematical model to iterate parameters.
Among the techniques, safety issues and noise problem should be taken into consideration.

This project is open for discussions.

Vieena Apple
IEEETM center

American National Standard for voltage ratings

From www.ien.com
American National Standard For Electric Power Systems and Equipment -- Voltage Ratings
Rosslyn, VA, January 16, 2007 -- The National Electrical Manufacturers Association (NEMA) has published ANSI C84.1-2006, American National Standard for Electric Power Systems and Equipment -- Voltage Ratings (60 Hertz).
This standard establishes nominal voltage ratings and operating tolerances for 60 Hz electric power systems above 100 volts. It also makes recommendations to other standardizing groups with respect to voltage ratings for equipment used on power systems and for utilization devices connected to such systems. ANSI C84.1-2006 includes preferred voltage ratings up to and including 1200 kV maximum system voltage.
In defining maximum system voltage, voltage transients and temporary overvoltages caused by abnormal system conditions such as faults, loads, and rejection are excluded. However, voltage transients and temporary overvoltages may affect equipment operating performance and may be considered in the individual product standards.
The standard was expanded to cover voltages from 230-1,200 kV, and the requirements from the Institute of Electrical and Electronics Engineers, Inc (IEEE) 1312, which covered these higher voltages, were incorporated into the C84.1 revision.....

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