In some enterprises and institutions, it is necessary to equip the departments to which they belong to diesel generator sets (referred to as: units). When the mains grid is out of power, the units can be started immediately to provide the required power in time for these departments. Usually, these units are operated and managed by dedicated personnel.

Design and use the diesel generator set monitoring network system (referred to as: the system), which can realize unmanned management and monitoring of multiple units. The system is composed of a monitoring host and a plurality of monitors installed in the machine room via a public telephone network. Among them, the monitor is used to detect and control the operating status and fault of each unit, the operating parameters of the unit, and the status of the power grid. The monitoring host communicates with each monitor through the public telephone network, and collects data detected by each monitor and provides it to the management personnel. The manager can know the status of each unit in time and can control the operation of each unit through the monitoring host.

The system has been successfully used in the monitoring of multiple 500 ~ 800kVA diesel generator sets, and effectively achieves the normal operation of each unit under unattended conditions.

2 The system structure of the computer room monitor is composed of public telephone network. Its structure is as shown.

The system structure diagram monitoring host can use the “telephone dialing” mode to communicate with the selected unit monitor via the modem (MODEM) to realize the communication and control functions of the system.

2.1 Monitoring host monitoring host by a general-purpose microcomputer or laptop in W! The NS environment is composed of dedicated software. Through the modem, it can be dialed with a telephone line to communicate with the specified unit monitor.

The main functions of the monitoring host are as follows.

Data communication can be realized by dialing with a telephone line and a monitor installed in each unit room. The communication method can be implemented by "fixed" or "scanned".

The operation of each unit can be controlled in a variety of ways. To meet the requirements of unit operation under different conditions.

The operating parameters of each unit can be stored and printed and displayed in a curved or tabular format.

Various modes of alarms can be performed for abnormal phenomena of each unit such as power grid blackout and unit fault. Such as voice alarm, display alarm, paging alarm and so on.

The monitoring console with laptop is extremely flexible.

The management personnel can dial and connect with the designated unit monitor at any time by any telephone line to realize the parameter collection and control of the monitor.

2.2 Monitor monitors are installed in each unit room. Its structure is as shown. The programmable controller used in the monitor adopts the OMROM-CQM series. This programmable controller has the characteristics of high reliability, many types of modules, strong functions and good programming environment.

The hardware of the monitor structure monitor consists of an internal processing part, an external monitoring and communication part. The part enclosed by the dotted line is the external monitoring and communication part.

The internal processing part is mainly composed of a programmable controller and various interface modules, and is composed of a sensor signal conditioning circuit and a unit state detection/control drive circuit.

The external monitoring and communication part consists of various sensors, unit fault detection circuit, unit operation control circuit, unit operation parameter detection circuit, voice alarm circuit, unit operation parameter display drive circuit and instrument, function operation button, work indicator, modem, etc. .

The main functions of the monitor are as follows.

When the grid is detected to be out of power, the monitor can automatically start the unit operation (or the operator manually) in a short period of time to meet the department's demand for electricity.

When the ambient temperature is low, the heating system of the unit can be controlled to heat the diesel engine body to ensure the starting performance of the unit.

The parameters and status of the unit operation can be detected in real time. Operating parameters include: voltage, current, frequency, unit starting battery voltage, cooling water temperature, diesel oil pressure, etc. when the unit is running. The operating status includes: unit speed alarm status, over temperature alarm status, and low water level status of the cooling water tank. The control output includes: starting and stopping of the unit.

The monitor displays all detected content in a clear and efficient manner. If using a digital meter to display the output voltage, current, frequency, etc. of the unit. Display and alarm the flashing and voice mode of any abnormalities detected, or send an alarm page through the public telephone network.

The unit can be operated in automatic operation mode or manual operation mode.

When the unit is unattended in the equipment room, the above functions can ensure the normal working requirements of the unit.

The functions of the main parts of the monitor are as follows.

The unit speed sensor, the water level sensor of the cooling water tank, the diesel oil pressure sensor and the grid state detector are used to detect the unit speed, cooling water level, diesel oil quantity, grid status, etc., and transmit the detected signals to the signal processing of the internal processing part. Circuit.

The internal sensor signal conditioning circuit conditions the signal sent by the external sensor to the internal required switching state, and then transmits it to the CPU unit of the programmable controller for processing.

The analog signal acquisition circuit is used to collect the AC voltage, current, cooling water temperature, etc. output from the unit, and transmit the collected signals to the internal analog/digital conversion module for conversion into digital quantities for processing by the CPU unit.

The function operation button is used to select the operation mode of the unit to meet the operation requirements of the unit under maintenance and special conditions.

The programmable controller is the core of the system. After programming, the selected operation mode of the unit and the externally sent detection signals can be effectively processed and correspondingly controlled. It sends the result of the processing to the display meter display. When there is an abnormal phenomenon, corresponding control processing can be made and various types of alarms can be performed through each alarm circuit.

The display instrument is used to display the running speed, output voltage, current and other values ​​of the unit in real time.

The voice alarm circuit can select the corresponding voice broadcast according to the alarm signal sent by the programmable controller. Make maintenance personnel in other rooms on time to know the abnormal situation of the unit.

The communication module is mainly composed of a modem and a serial interface (RS-232). The modem is connected to the public telephone network, so that the monitor can be used for network operation or alarm paging.

3 The main functions are designed to meet the operating requirements of the unit under unattended conditions, and the following operating modes and functions are designed and implemented.

3.1 Operation mode The operation mode of this system is divided into two types.

0 network operation mode: monitoring host and monitor network operation. In this mode of operation, both the monitoring host and the monitor can control the unit. At the same time, the parameters and abnormal phenomena of each unit are transmitted to the monitoring host in real time by the monitor. It is analyzed and processed by the monitoring host, and the results are displayed and printed, and an alarm can be issued when an abnormal situation occurs.

2) Non-networked operation mode, using the monitor to control the start, operation and shutdown of the unit, and detecting the operating parameters of the unit, monitoring, displaying and alarming the abnormal phenomena of the unit. 3.2 Monitoring host application design application function block diagram function. It can be run in "scan" or "fixed" mode. The so-called interval is synchronized with multiple monitors in turn.

In addition to the data communication between the monitoring host and the monitor, the two operating parties can display the operating parameters of each unit and alarm the abnormal phenomenon of the unit. The monitoring unit can also directly control the operation of the unit through the monitor.

Group operation parameters, such as the start time of each run, the running time, the output voltage, current, frequency and other data of the unit operation are collected, and the parameters of each operation of the unit are stored or deleted as data files.

The data file is queried or printed. It can be displayed and printed in the form of data curve or data table for users to analyze the operation of each unit.

And the telephone number of the communication is set, and the alarm parameter can be set, the organic group speed alarm value, the water level alarm value, the oil pressure alarm value, the starting battery voltage low alarm value, and the like.

3.3 Monitor Function The function of the monitor is designed based on the control requirements of the unit under unattended conditions. It can be networked with the monitoring host and can run independently in a non-networked manner.

The monitor has the following detection and control functions.

3.3.1 Monitor Detection Function The detection function of the monitor includes two aspects. When the mains power supply is normally supplied, the signals detected by the monitor include the temperature of the diesel engine body, the voltage of the starting battery, the oil pressure of the fuel tank, the water level of the cooling water tank, and the voltage and supply current of the mains, and the control display meter displays these. Parameters and status. When the mains grid is out of power and the unit is in normal operation, the signals detected by the monitor are the voltage, current, frequency, cooling water temperature, diesel oil pressure, diesel engine speed and other parameters, as well as the unit speed alarm, over temperature alarm, and cooling. The water tank has a low water level and other operating states.

During the detection process, the monitor stores the parameters of the unit at a certain time interval for the monitoring host to collect.

3.3.2 Control function of the monitor The control function of the monitor also includes two aspects. When the unit is inspected, the monitor can be set in the “manual control” mode, and the maintenance personnel can operate the relevant buttons to control the operation of the unit. The monitor can display the operating parameters and related status of the unit in this state. When the unit is normal, the monitor can be set in the "automatic control" mode. The monitor can control the start, run and stop of the unit according to the detection of the mains grid or the instructions transmitted by the monitoring host after networking.

3.4 Monitoring the communication protocol between the host and the monitor The communication between the host and the monitor is realized by a standard RS-232C serial port via a modem. The parameters used are: baud rate: 2400 bit/s; even parity; 7 data bits; Bit stop bit.

The communication protocol specifies the format of the data or control commands between the monitoring host and the monitor. These data and control instructions are as follows.

1) Uplink data transmitted by the monitor to the monitoring host, such as the status of the utility grid, the unit shutdown or related parameters and status during operation, and so on. These parameters and status are stored by the monitor in the continuous read operation space of the specified storage area, and are sent to the monitoring host by the monitor during transmission. The format is (turn to page 54). The system is divided into manual and automatic control modes. When there is a problem in the system automatic operation, it can be temporarily switched to manual operation.

4.2.1 Manual control The system has a manual operation panel. When the control mode is selected, the system can be started directly. The speed can be adjusted separately for each inverter. The emergency stop button can be used to stop the system in an accident. The fault reset button can be reset after the drive fault has been removed.

4.2.2 Automatic control By setting the process parameters on the man-machine interface “Parameter setting screen”, press the confirmation key to transfer the parameters to the PLC database, and calculate according to the “all ROLLER line speed ratio process calculation formulas listed in Section 2”. The given frequency of each inverter; by pressing the start button on the operation panel of the original system to issue a start command, the PLC will detect the external start signal, package the running command and the calculated given frequency value, and transmit it through the communication network. For each inverter and remote I/O, the control of each ROLLER and related equipment is completed. At the same time, the PLC reads back the status and data of each inverter and remote I/O, which is displayed by the touch screen in real time.

5 Conclusion The false-field machine field bus automatic control system was put into operation in early April 2001. It was in good working condition and reached the expected control requirements. It was officially accepted by the user unit in June 2001 and won the praise of relevant professionals. The system has low investment cost, short construction period and quick effect. The technicians of the user unit have obtained a lot of results on the long-term test of this equipment, and produced a large number of new products on other false twisting machines, which has achieved good economic efficiency.

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