power transformers is the most important electrical equipment in the power system, once emerged fault operation, the power system will cause significant achievements. Deformity running transformer core point grounding, 850ffdf61c6c9f5df2e51f5ca85c two points or two points more than at the same time ground, between the core and the earth will constitute a current loop, the maximum current can reach the number ten amps will cause the core to overheat or even destroyed. Determine whether the transformer core multi-point grounding important the the clamp meter three ways to regularly monitor the core electrical ground current approach, measuring core insulation resistance method, monitoring characteristics of transformer insulating oil gas by gas chromatography. The shortcomings of the above is not timely detection of multi-core grounding fault, in the event of a failure, nor with an appropriate and timely way. Thus, real-time online monitoring of ground current of the transformer core is very necessary.

Currently, on-site staff to take a more clamp meter clamp the core grounding line monitoring of its current DD estimates are very accurate, but because of the annoyance of the strong magnetic field of the transformer, and even presented the case of the unified measurement points several times different measurement value differences reference value measured so worthy of suspicion; installation of the development of active surveillance of the home and some units are able to discover the multi-point ground fault, but lack real-time fault monitoring functions. To this end, designed a line monitoring installation based on GSM communication, a better solution to the problem of online monitoring of the ground current of the transformer core. Small ground current in the normal state, to understand the decision by the scene annoyance but none serious questions.

1, target

large power transformer core current changes can reflect directly the the transformer fault state - whether there is a core multi-point grounding. Method is monitoring by substation staff on duty applications handheld instrument to detect and record on a regular basis, the biggest problem of the method is not immediately reflected the failure to make the existence of severe hazards to the further expansion of the Incident. Followed by the increase of electricity increased automation and unmanned substation, an urgent need for a solid, reliable, high precision and strong function of large power transformer core current line monitoring devices. The apparatus herein described, is designed for this purpose, with a high utilization value.

future development

11

Currently the kingdom is the development of intelligent power grid,power inverter, and the online monitoring system of the transformer core is formed more major constituent departments intelligent grid abroad in the early 1980s it has been the beginning of the on-line monitoring of transformer core system seminars and to achieve malformations of the unmanned substation, thrift large number of human and material resources, and can be timely and effective invention transformer core grounding point situation, and through a series of data can be parsed transformer exists the risk of multi-point grounding, better protect the transformer equipment operation. The kingdom in the insurance regulations have been proposed line monitoring of transformer core requests of all line monitoring of transformer core within five years of the current arrangements. Foreign scientific and technological workers and the relevant part of this schedule maintenance and preparedness experimental inadequacies long awareness has diverse committed to online monitoring of the electrical equipment with the condition inspection seminar. Its strength lies in timely invention early fault symptoms, possibly through early detection wrist dispel hidden fault nascent status, thus preventing the generation of malignant Incident and progress of the maintenance of the quality and effectiveness of running protection staff. Followed by the sensor techniques, signal disposal techniques with figuring machine technology development and utilization, as the state test of basic electrical equipment online monitoring technology has been rapid development, has become a major component of partial insulation testing, it will supplement in benign and multifaceted only dependent on schedule preparedness experiment brought inadequacies. Through the on-line monitoring of core grounding current, correct to conclude that the core of the work of state, which targeted core rendering before the failure timely protection powered solid progress, not only effective, but also the expense of the operation of the electricity system decline the protection of the safe running of the power transformer has a very important meaning.

12 the results of the use and promotion

121 to solve the outage overhaul the electricity part to pay a grand human, material costs, not only to the energy user inconvenience, there are still maintenance excess.

122 times the distance between the two preventive tests solve longer difficult to detect sudden insulation failure, the problem of lack of maintenance.

123 solve the differences of the test the prerequisite and run premise some offline test can not be a complete response to the insulation state of the device under operating conditions.

manmade new equipment failures scene generated solve the overhaul

124 and blackout test.

2, the purpose of

The contentment the overhaul of the power system of the transformer core state need, the

proposed design plan of the transformer core multi-point grounding-line monitoring system, the monitoring system should be satisfied with the following features 21 inputs and application of the monitoring system do not change, does not affect the normal operation of the transformer; 22 can be monitored continuously, records and disposal of data, timely alarm and fault diagnosis; 23 there is a good anti-interference ability and fair monitoring sensitivity; 24 system robustness, ease of maintenance, suitable for long-term operation; 25 effective governance data, a good man-machine interface.

3, the content

Based on the above, where appropriate, the need to achieve a number of research and work

31 core grounding current practice of profiling

based on the actual construction of the transformer core, establish a mathematical model for the core, figuring core point grounding current and multi-point ground fault current value and analyze fault current rules changes with the point of failure, for the supply of system design practice support .

32 system hardware circuit design

basis core grounding the request of the online monitoring system, designed to contain electrical propagation sensor, filtering, amplification, A / D conversion, data storage and restraint, including the data acquisition circuit, a signal for the ground current monitoring and extraction structures hardware platform.

33 system software design

programming based on the RS232 serial port of the high and low-bit machine communication, epistasis can be gripped by the next-bit machine running and can receive the next bit machine core ground current monitoring data collected to establish ground current online monitoring database,Grid tie inverter, data storage, questioning and other effects, and take LabVIEW to develop a set of ground current of the transformer core analysis software.

34 structure

system is spread by the leaked electric sensor, data acquisition cabinet, situ instrument, Serial Device Servers, routers and systems server

Serial Device Server supply TCP / UDP socket work mode, including services and client support status monitoring and Web announced. Each four RS-485 port Serial Device Server, allows each serial devices alone take up a serial port to reduce the different serial devices and up interference. Data acquisition cabinet acquisition transformer or reactor core and clamps the leakage current and connected through the serial port and networked server.

remote data acquisition module of the system to the real-time collection of transformers and other electrical equipment leakage current parameters passed to via RS-485 Serial Device Server, and then passed to the electricity LAN Serial Device Server has since convergence Even if the system is powered down, when the power is restored Serial Device Server to proactively connected to the LAN,www.12vgridtiepowerinverters***.

The local display

local instrument may be displayed in real time leak current parameters of transformers and other electrical equipment, and there is an audible alarm efficacy.