变频技术应用中英文翻译、外文文献翻译、plc可编程控制器外文翻译

变频技术应用 在工业现场控制领域，可编程控制器（ PLC）一直起着重要的作用。随着国家在供水行业的投资力度加大，水厂运行自动化水平不断提高， PLC 在供水行业应用逐步增多。触摸屏与 PLC 配套使用，使得 PLC 的应用更加灵活，同时可以设置参数、显示数据、以动画等形势描绘自动化过程，使得 PLC 的应用可视化。 变频恒压供水成为供水行业的一个主流，是保证供水管网在恒压的重要手段。现代变频器完善的网络通信工程，威电机的同步运行，远距离集中控制和在线监控等提供了必要的支持。通过与 PLC 连接的触摸屏，可以使控制更加 直观，操作更加简单、方便。组合应用 PLC、触摸屏及变频器，采用通信方式对变频器进行控制来实现变频恒压供水。 变频恒压供水系统原理如图 1；它主要由 PLC、变频器、触摸屏、压力变送器、动力及控制线路以及泵组组成。用户可以通过触摸屏控制系统的运行，也可以通过控制柜面板上的指示灯和按钮、转换开关来了解和控制系统的运行。通过安装在出水管网上的压力变送器，把出口压力信号变成 4 20mA 或 0 10V 标准信号送入 PLC 内置的 PID 调节器，经 PID 运算与给定压力参数进行比较，输出运行频率到变频器。控制系统由变频器控 制水泵的转速以调节供水量，根据用水量的不同， PLC 频率输出给定变频器的运行频率，从而调节水泵的转速，达到恒压供水。 PLC 设定的内部程序驱动 I/O 端口开关量的输出来实现切换交流接触器组，以此协调投入工作的水泵电机台数，并完成电机的启停、变频与工频的切换。通过调整投入工作的电机台数和控制电机组中一台电机的变频转速，使系统管网的工作压力始终稳定，进而达到恒压供水的目的。 该系统有手动和自动两种运行方式。手动方式时，通过控制柜上的启动和停止按钮控制水泵运行，可根据需要分别控制 1# 3#泵的启停，该方式主 要供设备调试、自动有故障和检修时使用。自动运行时，首先由 1#水泵变频运行，变频器输出频率从 0HZ 上升，同时 PID 调节器把接收的信号与给定压力比较运算后送给变频器控制。如压力不够，则频率上升到 50HZ，由 PLC 设定的程序驱动I/O 端口开关量的输出来实现切换交流接触器组，使得 1泵变频迅速切换为工频， 2泵变频启动，若压力仍达不到设定压力，则 2泵由变频切换成工频， 3泵变频启动；如用水量减少， PLC 控制从先起的泵开始切除，同时根据 PID调节参数使系统平稳运行，始终保持管网压力。 若有电源瞬时停电的情 况，则系统停机，待电源恢复正常后，人工启动，系统自动恢复到初始状态开始运行。变频自动功能是该系统最基本的功能，系统自动完成对多台泵的启动、停止、循环变频的全部操作过程。 在进行通信之前必须对 PLC、触摸屏和变频器的通讯参数进行正确设置。本系统定义为 Modbus 协议，波特率为 9600，数据位为 8，无校验，停止位为 1。变频器除设置通信参数外，还需启用 “自由停车 ”以保护电机。 PLC 通讯参数设置 :TWDLCAA24DRF硬件 端口 端口设置，在端口设置中进行端口参数设置；触摸屏通讯参数 设置： IO 管理器ModbusRTU01COM1Modbus Equipment，双击 “Modbus Equipment”即可进行通讯参数设置。 该系统采用施耐德的 TWDLCAA24DRF， I/O 点数为 24 点，继电器输出，PLC 编程采用施耐德 PLC 专用编程软件 Twidosoft，软件提供完整的编程环境，可进行离线编程、在线连接和调试。为了提高整个系统的性价比，该系统采用可编程控制器的开关量输入输出来控制电机的起停、自动投入、定期切换，供水泵的变频及故障的报警等，而且通过 PLC 内置的 PID 给定电机的转速、设定压力、频率、电流、电压等模拟信号量 。 施耐德 PLC 的编程指令简单易懂且程序设计灵活，步进计数器功能模块（ %SCi）提供了一系列的步，这些步可赋值给动作。从一个步移动到另一个步取决于外部或内部事件。通过模拟输入和输出模块TWAMM3HT以及内置的 PID 运算器，实现如图 2 的顺序切泵。 泵组切换示意图如图 2，工作条件满足，开始工作时， 1#泵变频启动，泵的转速随变频器输出频率的上升而逐渐升高，如变频器的频率达到 50HZ而此时水压还未达到设定值， PLC 内置的程序控制使得切换到下一个工作步 ，延时一段时间后， 1泵迅速切换至工频运行，同时解除变频器运行信号，使变频器频率降为 0HZ，然后 2泵变频启动，若压力仍未达到，则 2泵切换至工频， 3泵变频启动，在运行中始终保持一台泵变频运行，当压力达到设定值时变频输出将为0HZ，同时 PLC 通过 I/O 端口跳到下一个工步，由 PLC 决定切除 1工频泵，此时由一台工频泵和一台变频泵运行，如果此时压力达到设定值，变频器的输出为0HZ，再切换到下一个工步， PLC 解除 2工频泵，只由 3泵变频运行来维持管网压力。当压力下降，变频器频率升至 50HZ输出信号，延时后 3 泵切换为工频， 1泵变频启动，若压力仍不满足则 1变切换为 1工， 2泵变频运行，如果压力仍达不到， 2变切换为 2工，启动 3变，三台泵同时工作以保证供水要求。 这样的切换过程有效地减少泵的频繁起停，同时在实际管网对水压波动做出反应之前，由变频器迅速调节，使水压平稳过渡，从而有效的避免了高楼用户短时间停水的情况发生。 以往的变频恒压供水系统在水压高时，通常采用停变频泵，再将变频器以工频运行方式切换到正在以工频运行的泵上进行调节。这种切换的方式理论上要比直接切换工频的方式先进，但其容易引 起泵组的频繁起停，从而减少设备的使用寿命。而在该系统中采用直接停工频泵的运行方式，同时由变频器迅速调节，只要参数设置合适，即可实现泵组的无冲击切换，使水压过渡平稳，有效的防止了水压的大范围波动及水压太低时的短时间缺水的现象，提高了供水品质。 该系统采用 PLC 和变频器结合，系统运行平稳可靠，实现了真正意义上的无人职守的全自动循环切泵、变频运行，保证了各台水泵运行效率的最优和设备的稳定运转启动平稳，消除了启动大电流冲击，由于泵的平均转速降低了，从而可延长泵的使用寿命，可以消除启动和停机时的水锤效应。通过 触摸屏上的人机界面就可进行供水压力的设定，监视设备运行状况同时可以查询设备故障信息，大大提高恒压供水系统的自动化水平及对现场设备的监控能力。The application of exchange frequency Introduction in the industry scene control domain, the programmable controller (PLC) has been playing the vital role. Enlarges along with the country in the water supply professions investment efforts, the water works movement automation level enhances unceasingly, PLC increases gradually in the water supply profession application. The touchscreen and the PLC necessary use, causes PLC the applicatio n to be more flexible, simultaneously may establish situation description automation processes and so on parameter, demonstration data, by animation, causes PLC the application visualization. The frequency conversion constant pressure water supply becomes the water supply profession a mainstream, is guarantees the water supply pipe network in the constant pressure important means. The modern frequency changer perfect network service project, the prestige electrical machinerys synchronized movement, the long-distance range common control and the online monitoring and so on have provided the essential support. Through with the PLC connections touchscreen, may cause the control to be more direct-viewing, the operation is simpler conveniently. The combination using PLC, the touchscreen and the frequency changer, uses the mailing address to carry on the control to the frequency changer to realize the frequency conversion constant pressure water supply Frequency conversion constant pressure water supply system principle like chart 1； It mainly by PLC, the frequency changer, the touchscreen, the pressure transmitting instrument, the power and the control wiring as well as the pump group is composed. The user may through the touchscreen control systems movement, may also through the control cubicle kneading boards on indicating lamp and the button, the change-over switch understands and control systems movement. Through installs in the outlet pipe on-line pressure transmitting instrument, turns 420mA or the 010V standard the outlet pressure signal The signal sends in PLC the built-in PID regulator, with assigns the pressure parameter after the PID operation to carry on the comparison, the output movement frequency to the frequency changer. The control system controls water pumps rotational speed by the frequency changer to adjust the volume of diversion, according to the water consumption difference, the PLC frequency output assigns frequency changers movement frequency, thus adjusts water pumps rotational speed, achieves the constant pressure water supply. The PLC hypothesiss internal procedure actuates the I/O port switch quantity to lose realizes the cut exchange to meet Touches the group, puts into the work coordinated by the water pump electricity radio station number, and completes the electrical machinery to open stops, the frequency conversion and the power frequency cut. Through in the adjustment investment works electricity radio station number and the control electrical machinery an electrical machinerys frequency conversion rotational speed, causes the system pipe networks working pressure to stabilize throughout, then achieves the constant pressure water supply the goal. This system has manual and the automatic two movement way. When manual way, through control cubicles on start and the pause button control water pump movement, may according to need to control the 1#3# pump to open separately stops, this way mainly for the equipment debugging, automatically has time the breakdown and the overhaul uses. When automatic movement, first by the 1# water pump frequency conversion movement, the frequency changer output frequency from the 0HZ rise, simultaneously the PID regulator after assigning the pressure comparison operation gives the receive signal the frequency changer control. If the pressure is insufficient, then the frequency rises 50HZ, actuates the I/O port switch quantity by the PLC hypothesiss procedure to lose realizes the cut exchange contact device group, causes the 1# pump frequency conversion rapid cut is the power frequency, the 2# pump frequency conversion starts, if the pressure still could not achieve the hypothesis pressure, then 2# The pump cuts the power frequency by the frequency conversion, 3# the pump frequency conversion start； If the water consumption reduces, the PLC control gets up formerly the pump starts to excise, simultaneously causes the system according to the PID adjustment parameter to move steadily, maintains the pipe network pressure throughout. If has the power source instant power cut situation, then the system engine off, after treating the power source restores normally, manually actuated, the system self-recovery to the original state starts to move. The frequency conversion automatic function is this system most basic function, the system completes automatically to many pumps starts, the stop, the circulation frequency conversion complete operating process。 Plant parameters establishment before carrying on the correspondence must to PLC, the touchscreen and frequency changers communication parameter carries on the correct establishment. This system definition is the Modbus agreement, the baudrate is 9600, the data position is 8, does not have the verification, stops the position is 1. Frequency changer besides establishment correspondence parameter, but must begin using “the free parking” to protect the electrical machinery. PLC communication parameter establishment: The TWDLCAA24DRF- hardware - - port - - port establishment, carries on the port parameter establishment in the port establishment； Touchscreen communication parameter establishment: IO supervisor - - ModbusRTU01COM1-Modbus Equipment, the double click “Modbus Equipment” then carries on the communication parameter establishment This system uses Shinaide TWDLCAA24DRF, I/O points is 24 spots, the relay outputs, the PLC programming uses Shinaide PLC special-purpose programming software Twidosoft, the software provides the complete programming environment, may carry on the off-line programming, the online connection and the debugging. In order to enhance the overall system The performance-to-price ratio, this system uses the programmable controllers switch quantity input to lose controls the electrical machinery to stop, the automatic investment, the regular cut, water supply pumps frequency conversion and the breakdown warning and so on, moreover assigns simulated signal quantities and so on electrical machinerys rotational speed, hypothesis pressure, frequency, electric current, voltage through PLC built-in PID. The pump group cuts the schematic drawing like chart 2, the working condition satisfies, starts when works, the 1# pump frequency conversion starts, pumps rotational speed elevates gradually along with the frequency changer output frequencys rise, if frequency changers frequency achieves 50HZ, but this time hydraulic pressure has not achieved the setting value, the PLC built-in programmed control causes to cut the next work step, after time delay period of time, the 1# pump rapid cut to the power frequency movement, simultaneously relieves the frequency changer movement signal, causes the frequency changer frequency to reduce to 0HZ, then the 2# pump frequency conversion starts, if the pressure had still not achieved, then the 2# pump cut to the power frequency, the 3# pump frequency conversion starts, maintains a pump frequency conversion movement throughout in the movement, when the pressure achieves the setting value the frequency conversion output will be 0HZ, simultaneously PLC jumps through the I/O port to the next labor step, by PLC decided that excises the 1# power frequency pump, this time by a power frequency pump and a frequency conversion pump movement, if this time pressure achieves the setting value, frequency changers losing Leaves is 0HZ, cuts the next labor again step, PLC relieves the 2# power frequency pump, only maintains the pipe network pressure by the 3# pump frequency conversion movement. When the drop of pressure, the frequency changer frequency climbs to the 50HZ output signal, after the time delay, the 3# pump cut is the power frequency, the 1# pump frequency conversion starts, if the pressure still did not satisfy, then 1# changes the cut is the 1# labor, 2# pump frequency conversion movement, if the pressure still could not achieve, 2# changes the cut is the 2# labor, starts 3# changes, three pumps simultaneously work guarantee the water supply request. Such cut process reduces the pump to be frequent effectively stops, simultaneously in the actual pipe network makes the response before the hydraulic pressure fluctuation, adjusts rapidly by the frequency changer, causes the hydraulic pressure stable transition, thus effective has avoided the situation occurrence which the tall building user short time cuts off the water supply. Former frequency conversion constant pressure water supply system when height of water, usually uses stops the frequency conversion pump, cuts again the frequency changer by the power frequency movement way is carrying on by on the power frequency movement pump the adjustment. This cuts way must be more advanced than theoretically the direct cut power frequency way, but it easy to cause the pump group to be frequent stops, thus reduces equipments service life. But uses in this system stops