The common LCU screen is mainly used to monitor the oil, gas and water system in the station. Ensure the safe operation of the unit, auxiliary equipment and the whole plant utility system, and ensure the correct and reliable monitoring of oil, gas, water and other important utility equipment. At present, the LCU screen is more and more widely used. Whether it is the pump station or the gate, in order to better control the whole system, the first thing is to measure and collect the physical phenomena such as voltage, current, temperature, pressure and sound, and then deal with them.

The Internet of Things gateway supports communication acquisition and forwarding of various switching quantities, analog quantities and PLC intelligent devices, as well as host computers, WEB configuration and low code platforms of various electrical equipment

Data acquisition technology is widely used in many other industries. All data acquisition tools such as cameras and microphones. The data collected are various physical quantities that have been converted into electrical signals, such as temperature, water level, wind speed, pressure, etc. It can be analog or digital. In the process of collection, different sampling methods are usually adopted, namely repeated collection of data at the same point (called sampling cycle). Most of the data collected are transient values, but there is also an eigenvalue in a given period of time. The basis of data acquisition is accurate data measurement. Measurement data methods include contact method and non-contact method, detection elements. No matter what method and element, to ensure the correctness of the data, do not affect the state of the measured object and measurement environment. It is a broad method of data acquisition, and it is a continuous physical quantity relative to another. In computer-aided drafting, cartography, and design, the process of digitizing a graph or image may also be called data acquisition, in which geometric (or physical, such as grayscale) data is collected.

With the rapid development of network and digital transmission technology, data acquisition has been widely used in the network and distributed field, and the field of data acquisition has undergone significant changes.

First, in distributed control, intelligent data acquisition system has been developed greatly at home and abroad. Secondly, more and more data acquisition plug-ins are compatible with bus, and more and more data acquisition systems are compatible with PC. Various data acquisition machines have appeared at home and abroad, which makes data acquisition enter a new era.

Iot gateway supports various switching analog quantities, communication acquisition and forwarding of PLC intelligent devices, host computer of various electrical equipment, WEB configuration and low code platform

Data acquisition and processing function of LCU control cabinet.

The device LCU can realize the real-time acquisition and processing of the operating state, operating parameters and measured values of the main and auxiliary equipment of the unit, and store them in the real-time database as the basis for real-time monitoring, alarm, control, tabulation and calculation. LCU screens usually need to collect data such as analog value, switching value, temperature value and electrical value. If there is to collect some special data, also only need to through the PLC programming, in addition to add acquisition tools, data can be acquired.

a) Analog quantity

The analog quantity is divided into electric analog quantity, non-electric analog quantity and temperature measurement.

The analog quantity is collected by AC sampling, current and voltage signals of CT and PT are collected regularly, and relevant values such as current, voltage, power and frequency are calculated. Non-electric quantity and partial electric quantity are realized by 4-20mA analog quantity acquisition. The processing of analog signal includes circuit break detection, digital filtering, error compensation, data validity and rationality judgment, scale conversion, gradient calculation, overrun judgment and overrun alarm, etc. The Ws series isolators are used for non-electrical analog inputs to ensure good input results. The analog is stored in a real-time database after design and formatting.

b) switching quantity

Switching quantity is divided into event sequence recording (SOE) switching quantity and ordinary switching quantity. The processing of switching signals includes photoelectric isolation, software and hardware filtering, reference time compensation, data validity judgment, startup related processing functions (such as startup event sequence recording, accident alarm, automatic push out and automatic stop, etc.). , and finally format it and store it in the real-time database.

So the amount of switching refers to accidents, circuit breakers, important electrical and hydraulic protection of the action signal. The monitoring system uses a fast scanning method to detect these motion signals and records them with a time resolution of milliseconds.

General switching quantity refers to various fault signals, alarm signals, isolation switch position, equipment status, etc. The SOE switching quantity is excluded. The monitoring system periodically scans the total switch value.

c) Comprehensive quantity

Comprehensive capacity includes comprehensive switching capacity and comprehensive analog capacity, which is the quantity obtained through the above four logical operations, such as unit state, busbar state, circuit breaker, number of protection actions, etc.

Unit LCU control cabinet, as the name implies, is used in the unit automation system PLC (programmable logic controller), it has powerful function, small size, easy to use and so on. This paper mainly introduces its composition and working principle from two aspects:

Composition and working principle:

1. Composition:

Unit LCU is mainly composed of CPU (microprocessor), input/output module, power module and communication network.

(1) CPU:

The microprocessor is the "brain" of the unit, which is responsible for receiving instructions from the field and processing these information through the internal program before issuing instructions to other components to execute.

(2) Input/Output:

This part of the module is composed of input/output outlets and corresponding relays.

(3) Power module.

(4) Communication network.

2. Working principle:

(1) When the unit receives the command from the operator, it first converts the field command signal into the corresponding level signal and sends it to the CPU for processing; Then the processed data is sent to the relevant input or output unit for processing according to the need; When the processing is complete, the information will be fed back to the site for the reference of the operator.

(2) For some complicated programs, in order to ensure their correctness, a certain degree of redundancy is usually set in the program to prevent the occurrence of program errors or misactions and other unexpected situations.

(3) If there is a fault in the whole operation process, the operation can be stopped by tripping so as to protect the safety of the equipment.

(4) If there is a power failure accident, you can also use the way of tripping to quickly restore the power supply.

3. Precautions:

1) In daily work, it is necessary to operate in strict accordance with the regulations to ensure the safe and stable operation of the unit;

2) For some special working environment such as high temperature and high pressure, reasonable emergency measures should be formulated according to the actual situation to ensure the normal operation of the equipment;

3) In the process of maintenance, attention should also be paid to take good safety precautions to avoid personal injury accidents.

Oil system control: It is mainly used for lubrication of upper guide bearing, lower guide bearing and hydraulic turbine guide bearing of generator and oil control of governor oil pressure device operation.

Technical water supply and drainage system control: technical water supply system is mainly used for generator air cooler, bearing cooler, plant domestic water control. The drainage system mainly includes turbine main shaft seal, butterfly valve leakage, air compressor room drainage, water seepage of the underwater part of the hydraulic structure of the workshop, domestic drainage and so on.

Gas system control: medium pressure gas system is mainly used for governor oil pressure device gas supply; The low pressure gas system is mainly used for the normal braking gas of the unit, the maintenance and sealing of the turbine, the purge and the gas for pneumatic tools.

(1) Requirements for control operation safety

After receiving the control command, the LCU checks the locking conditions associated with the operation and permits the operation only when the requirements are met.

When the LCU detects the module fault online, the corresponding control function is automatically disabled.

When the LCU receives the control command from the power plant, it will ensure the correctness of the control command transmission by sending back the check and other steps.

During the operation, the LCD screen displays the operation monitoring screen. When the control process is blocked, the blocked reason will be given;

LCU has local/remote control mode switch button, local and remote control interlock;

Take necessary logical judgment to reduce the possibility of accidental shutdown by false start.

(2) Data communication

LCU communications include the following:

a) As a node in the monitoring system network, it can communicate with the power plant level, send data acquisition and event information to the upper computer, accept the control command of the lower line and send the execution result back to the main control level;

b) As a local control unit to realize the communication with various intelligent acquisition devices and other devices, support popular modbus, profibus and other protocols, meet and adapt to the special requirements of field devices.

(3) Self-diagnosis

LCU can diagnose hardware and software online and offline, diagnose hardware to board level, and alarm when fault is diagnosed online, and automatically perform redundant switching, locking control and other processing.

(4) Configuration and software development

LCU can develop, edit, and configure software online and offline.