Shunyang brand capacitive voltage transformer CVT online monitoring device has been successfully put into operation in Zhejiang Power Grid for five years
- Categories:Shunyang News
- Author:Fu Jinlong
- Time of issue:2011-04-11
With the development of social economy, the requirements for the reliability and economy of power system operation are getting higher and higher, which has promoted the development of the current power equipment maintenance mode from "regular maintenance" to "conditional maintenance", so the operation of power equipment It is imperative to conduct online monitoring and live detection of status.
Capacitive voltage transformer (CVT) has obvious advantages such as anti-ferromagnetic resonance, relatively high performance and price, and small operation and maintenance workload, and has been widely used. It has become the main measurement device in high voltage levels for voltage and power measurement, Electric energy measurement, relay protection, automatic control, etc., and can also be used as a coupling capacitor for power line carrier communication systems.
With the large-scale use of CVT, like other electrical equipment, there are still a certain percentage of obstacles and defects in CVT during operation, and there is a varying degree of upward trend. Once a fault occurs, it will inevitably affect the normal functions of relay protection and metering and endanger the safe operation of the power grid.
However, CVT is a fully sealed device. Except for oil leakage and abnormal noise, which will be obvious from the outside, other obstacles and defects are generally difficult to visually find. Certain technical measures must be adopted to detect the possibility of operation as soon as possible. abnormal situation. It can be known from the working characteristics of CVT that the CVT itself is a measuring instrument, and the amplitude, phase and waveform of the secondary voltage can reflect the operating conditions of the equipment itself. Article 21 of "110(66)kV-500kV Transformer Operation Specification" in National Grid Biotechnology  No. 172 "Operation Specification for Power Transmission and Transformation Equipment" "Capacitance voltage transformer secondary voltage abnormal phenomenon and its cause The main reason has clarified the abnormal conditions and reasons that may occur in the normal operation of CVT.
(1) Secondary voltage fluctuation: The main cause may be loose secondary connection; the low voltage terminal of the voltage divider is not grounded or the carrier coil is not connected; the capacitor unit may be intermittently broken down; it is caused by ferromagnetic resonance;
(2) Low secondary voltage: The main cause may be poor secondary connection; electromagnetic unit failure or capacitor unit C2 damage;
(3) High secondary voltage: The main cause may be that the capacitor unit C1 is damaged; the ground terminal of the voltage dividing capacitor is not grounded;
(4) Abnormal rise of open triangle voltage: The main cause may be the failure of the capacitor unit of a mutual inductor.
Ningbo Shunyang Electric Measuring Instrument Co., Ltd. successfully developed a three-phase and single-phase CVT online monitoring device in August 2006 according to the requirements of Hangzhou Electric Power Bureau, which was approved by Hangzhou Electric Power Bureau and put into operation in the substations of Hangzhou Electric Power Bureau. Its monitoring principle is that when the capacitor is damaged or the insulation is abnormal, the secondary side voltage of the CVT will change accordingly, and the voltage between the phases will appear large imbalance, and the opening delta voltage 3U0 will be greater than its value. At the setting value, the single-phase voltage will also exceed the normal value, and the single-phase voltage will also exceed the normal value. CVT online monitoring can monitor and analyze this change in real time. Once it detects that the CVT voltage exceeds the set normal range, it will quickly send an alarm signal, and at the same time make the output contact actuate, start the corresponding equipment, or urge maintenance personnel to deal with it quickly. Since the set alarm value is generally lower than its operating limit (from normal to the critical value of damage), an alarm and reminder can be issued when an accident occurs, so as to avoid the occurrence of CVT equipment damage accidents. The Shunyang CVT online monitoring device is also equipped with an RS232/RS485 interface, which can remotely transmit the status information of the CVT operation for processing by off-site monitoring agencies.
Reliable application in the past five years-time has proved that the product is stable;
Constant demand-it is the affirmation of the work of Sunyang by various power departments.
In the face of achievements, we need to work harder. Shunyang Electric Measuring Instrument Co., Ltd. will continue to provide stable quality equipment and services for the construction of the national smart grid.
April 11, 2011