Journal of Hubei Institute of Technology, Automatic Control System for Diesel Generator Sets, Jian Jun, Chen Gang, Chen Dingfang 2 (1 Department of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China; 2 Institute of Intelligent Manufacturing and Control, Wuhan University of Technology, Wuhan 430063, China) The genset automatic control system includes system functions, hardware components, and programming.
Diesel generators; backup power; automatic control of diesel generator sets as backup power sources, has been widely used in various industries. In particular, with the rapid development of cities and industries, the popularity of automation and computers requires the provision of stable power supplies.
Therefore, in the case of grid power failure, the research on the automatic control system for the diesel generator set to start the power supply quickly and ensure the normal and stable operation of the unit is also increasingly important. This paper introduces a diesel generator set as a backup power source, which can be quickly started in the event of a power outage of the grid, providing an automatic control system for stable power supply.
1 System function 1.1 The unit automatically maintains the ready-to-run state. When the grid is out of power, the backup power supply is generally required to start the power supply urgently. However, the unit must go through the warm-up operation and the normal operation of the load-carrying power supply from the start-up to the power supply. If the unit is restarted from the cold machine, it will often cause unsuccessful start-up and even affect the service life of the diesel engine. Therefore, in the case of normal power supply to the grid, the crew must automatically maintain operational readiness.
1.1.1 Preheating of Cooling Water Oil When the control system detects the water temperature and the oil temperature is lower than the set temperature, the preheating system is started to heat up. When the heating does not meet the requirements for a certain period of time, an audible and visual alarm is issued to check the failure of the preheating system.
2 Maintain the oil pressure of the oil below the set value and start the pump oil. If the pump oil does not meet the requirements for a certain period of time, an audible and visual alarm will be issued to check the pump oil system failure.
3 units of the regular self-lubricating unit in the idle state, start the no-load operation regularly, and check the various operating parameters.
1.2 The unit starts the power supply. After the grid voltage is lower than the set value for a specified time, it will automatically open to the grid, and at the same time start the unit, speed up, close, and supply power to the load.
If the first start of the unit is unsuccessful, the control unit will start again after a delay of 10s. If the start is not successful for three consecutive times, a start failure alarm signal will be issued.
1.3 Maintain unit operation status After the unit starts power supply, it detects various operating parameters such as cooling water temperature, oil temperature, oil pressure, diesel engine speed and output voltage and current. When the operating parameters are outside the set range, the system automatically adjusts. If the specified range is still not adjusted after a certain period of time, an alarm signal or opening, shutdown, and emergency stop will be issued.
1.4 Unit shutdown When the grid voltage is higher than the set value for a specified time, it will automatically close with the grid. At the same time, after the unit is cooled, the unit will stop normally. 1.5 Unit alarm and self-protection function The unit continuously detects the operating parameters and power parameters of the unit in idle and running state, exceeds the parameter setting range, issues an alarm, or adopts self-protection (such as opening and stopping, emergency stop).
2 The overall structural system of the system adopts a modular structure (see).
Power parameter module power module operation parameter module main module display module output execution module communication module alarm module keyboard module system hardware structure block diagram The main module takes the single chip microcomputer 8031 ​​as the core, including 2764 626428648255 and multi-channel sampling converter. Store the user program, set the parameters, complete the analog quantity read operation of the input switch, perform data operation and logic operation, write the result to the corresponding output interface, and drive the actuator.
The power parameter module completes the voltage measurement of the grid, unit supply voltage, current, and battery. The power parameters are measured by the Chengdu Electric Research Institute's power sensor|31. After the voltage and current are transformed, rectified and filtered, the output (0~5)V DC signal is sent to the multi-channel sampling converter.
The measurement of operating parameters includes the measurement of the temperature, pressure of the oil, the temperature of the cooling water, the speed of the diesel engine, etc., which are measured by the sensor and converted to output a DC voltage of (10 5 V).
The display module displays the current operating status, the measured parameters, and the online modified settings. The communication module implements communication with the host computer. The keyboard module inputs control commands and setting parameters. The output execution module outputs the control commands of the main module, such as shutdown emergency stop, start unit, heating, closing, opening, and the like.
The adjustment of the unit voltage is done by an automatic voltage regulator. During the operation, the frequency of the voltage should be adjusted according to the change of the grid load, and the speed of the diesel engine should be continuously adjusted to keep the grid frequency stable. The speed of the diesel engine is automatically controlled by an electronic governor.
3 Program Introduction According to the system function requirements and hardware structure, the control program is written. The system program consists of the main program unit regular self-lubricating subroutine, unit start subroutine unit speed control subroutine, unit running program, unit stop subroutine, display subroutine, communication subroutine and so on.
The main program maintains the operational readiness state, monitors the state parameters of the machine unit in real time, and calls each subroutine according to the measurement parameters and system setting values. The main program flow chart is as shown.
The startup subroutine completes the start-up, speed-up, output unit voltage, closing, and load operation of the unit. The subroutine block diagram is as shown. The unit sets three self-starting functions and three starts failure alarms. The initial value of n is 0. Self-protection has three situations: alarm, shutdown, and emergency stop.
Run the subroutine to complete the measurement of the power parameters and operating parameters, and compare the measured values ​​with the set values. If the setting range is exceeded, the corresponding self-protection function is activated. Monitoring the grid, if the grid is valid, after the delay is set, the grid is closed and transferred to the shutdown subroutine.
The unit shutdown subroutine completes the process of electromechanical opening, unit no-load operation, unit cooling, and unit shutdown. And measure whether the unit is stopped within the set time, otherwise it will issue a unit shutdown failure alarm.
4 Conclusion The control system has been installed and is running normally. The control requirements have been completed and satisfactory control results have been achieved. Further promote and apply in the future, and improve the parallel operation of multiple units and realize “three remotesâ€.
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