Distributed cable middle head temperature monitori

  • Detail

The measuring and monitoring system of temperature of cable connection at TG No.5 power station, including its hardware component, theory, characteristic and software function, are introduced It can run steadily and get a good effect.

keywords:high voltage cable tunnel cable connection temperature monitor on line

[Chinese Library Classification Number] tp23 [document identification code] B article number (2002) -

1 overview

TISCO has 5 main tunnels outside the station and 20 cable trenches. Most of the cable trenches do not meet the inspection conditions, so it is impossible to carry out spot inspection, and the power supply of important users mostly adopts direct distribution cables, which are laid in the cable trench. After long-term operation, the middle end of the cable in the trench is prone to explosion due to temperature rise and aging, causing power supply interruption, system impact and affecting the production of users. The cable explosion occurred in TISCO in, causing 49 trips. The explosion of cable head will not only cause power supply interruption, but also affect the production of users; In serious cases, it will also cause fire, resulting in long-term and large-scale power failure. If the temperature detection and prevention of the cable head in the trench can be solved, the hidden danger of high temperature of the cable head can be found in time, and the power failure can be handled, the explosion accident can be avoided. Therefore, cable head temperature monitoring is very necessary to achieve safe power supply. For this reason, we have developed the temperature monitoring system of the middle end of the distributed cable for the long-term use of the experimental machine in the fifth step-down station of TISCO

2 system composition and principle

2.1 in addition, system composition

system composition is shown in Figure 1. The system is mainly composed of monitoring machine, communication control machine, data acquisition unit (lower computer), sensor and RS-485 bus. The system adopts a distributed structure, and the data acquisition unit is connected to the RS-485 bus. The amount of wiring is small, which makes the system more flexible in adding and subtracting detection points and modifying the location of detection points

l the sensor adopts high-precision digital sensor JL-2, and the data acquisition unit provides DC working voltage and outputs digital signals. The sensor is a high-voltage resistant product, which can adapt to harsh environments through special waterproof, dustproof and shockproof packaging. The connection method of the sensor is one line and multiple points, and the special waterproof junction box is used to hang on the data line and power line

l the data acquisition unit (lower computer) detects the temperature or water level in real time, and transmits the collected value to the communication control computer through RS-485 bus. Each data acquisition unit can be connected with 20 sensors, and the sensor can be as far as 200m. Photoelectric isolation is adopted between the lower computer and the system, which is installed in the cable trench, fully sealed, and has the ability to prevent moisture and electromagnetic interference

l the communicator is responsible for processing the data on RS-485 bus, and sending the processed temperature signal and status information to the monitor through 232 port. It can process the data of two 485 buses at the same time, and can indicate the receiving and sending status of the bus, the working status of the communicator, etc

2.2 system principle

first, sort out the 76 cable heads in the station cable main tunnel and main trench, list, classify, number and establish files one by one. For example, the first cable head of 1 × lower computer is the first cable head of the 01st cable of continuous casting 3 × line, which is 28m away from T01 cable trench. Install temperature sensors on the cable head in the trench one by one, and measure the temperature of the cable head through the sensor and collect it to the lower computer

its working procedure is that the host sends instructions to the lower computer respectively. After receiving the host's instructions, the lower computer sends data to the communicator in turn. After receiving the data, the communicator judges and processes it, and then packages it to the host. The lower computer continuously collects data, updates and manages the sensors in this area, and judges their working status. The system updates the data every 1s. If it finds that the temperature rises, it will give an alarm in time. According to the alarm information, it can reasonably arrange the power outage maintenance, so as to eliminate the accident in the bud

3 software introduction and system functions

the monitoring machine adopts Windows 98 operating system, and the monitoring software is developed by visual Basic6.0

3.1 communication software

RS232 communication is adopted between upper computer and communication machine, and RS485 communication is adopted between communication machine and lower computer, The protocol and settings are as follows:

(1) communicator

baud rate check bit data bit stop bit communication port station address

9600 even check 7-bit 1-bit COM3 00h

(2) Lower computer

baud rate check bit data bit stop bit station address

1# 9600 even check 7 bits 1 bit 11h

2# 9600 even check 7 bits 1 bit 13h

3# 9600 even check 7 bits 1 bit 15h

4# 9600 even check 7 bits 1 bit 17h

5# 9600 even check 7 bits 1 bit 19h

3.2 application software

(1) system structure diagram interface

Figure 2 is the main interface of the monitor, from which we can see the system structure configuration The number of data acquisition units and the number of sensors carried by each unit. This screen can realize over temperature alarm display and system fault display. By placing the mouse on a measuring point, the name, collected value, serial number in the library, address and other parameters of the point can be displayed

(2) sensor distribution diagram

Figure 3 is the overall layout of the cable head, in which the actual position of the data acquisition unit and the sensor and the cable laying direction are marked. When there is an overtemperature alarm, the position of the alarm point is accurately displayed on the diagram in the form of sound and light, as shown in Figure 3. When the sensor temperature or water level exceeds the limit, it turns red. The attendant can also click the icons of data acquisition unit and sensor in the figure to view their parameters

3.3 system function

(1) temperature value sorting

the system can sort the values of all temperature measuring points from large to small, so that users can more easily master the measuring points with high temperature in the system, and can also display the temperature of the same circuit, that is, the temperatures of different position joints on the same cable and the cable body are displayed on the screen for comparison at the same time, so as to clearly understand the temperature change of the cable

(2) data query

monitor vigorously develops the new energy vehicle industry. After processing the temperature and water level status signals sent by the communicator, they are saved in the historical database for data query, report generation and fault recall. The query system takes the date as the index, but only by constantly improving the technical level of products can it be in an invincible position in the fierce international market competition. Historical data and fault records can be queried, detected and printed in the form of statements and curves

(3) fault prompt

the sensor and lower computer turn yellow in case of fault, and can point out the cause of the fault (disconnection, etc.)

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