外文翻译-变频器在恒压供水中的应用

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1、变频器在供水控制系统的应用 目前，在水位控制中有很大一部分水泵电机是不变速拖动系统，不变速电机 的电能大多消耗在适应供水量的变化而频繁的开停水泵中。 这样不但使电机工作 在低效区、减短电机的使用寿命，而且电机的频繁开停使设备故障率很高，导致 水资源严重浪费，系统的维护、维修工作量较大。 随着高位生活用水和工业用水逐渐增多，传统的控制方法已经落后。原先 用人工进行水位控制，由于无法每时每刻对水位进行准确的定位监测，很难准确 控制水泵的起停；使用浮标或机械等水位控制装置使供水状况有了一些改变，但 由于机械装 置的故障多，可靠性差，给维修带来很大的麻烦。 变频技术以其在节能与恒压方面的优越性能可以解

2、决水压控制系统存在的 以上问题。考虑选用单片机或 PLC 与变频器结合为核心构成的系统都能达到较 好的控制效果。但在软件设计上， PLC 比单片机的编程更简洁、直观；从硬件接 口考虑，单片机电路稍微复杂一些；从经济方面考虑，由于 PLC 工艺的日渐成 熟，小型 PLC 的成本与单片机相差无几，由于要根据现场情况调整系统参数， PLC 的软件中时间参数的调整更简单，这样更有利于售后服务人员掌握。基于以 上原因，选用了 OMRON 的 CPM1 系列 PLC 与 ABB 的变频器作为控制核心，再 加上 PSW7 调节器与 WSP300 压力变送器，控制效果非常好，软件设计简单， 硬件接口简易可行、

3、可靠性高，整个系统的性价比非常高。 在供水系统中引进变频器结合小型 PLC 技术，不仅改变传统用阀门控制水 量多少，而且在节能、恒压控制等方面均有非常好的效果，本文介绍了变频器 -PLC 调控技术在水泵控制中的应用。 控制系统用一台变频器可以带三台水泵， 每台水泵既可以工作在常规工频泵 模式， 也可以工作在变频泵模式。 每台泵 只能处于变频或工频其中一种工作模式， 通过两个继电器互锁保证它的安全与可靠。系统的结构如图一所示，利用安置在 的生活用水中的压力变送器将水的压力信号传输到调节器， 根据与调节器的设定 值和报警上下限比较，送信号给 PLC 与变频器，系统的起停泵分别由调节器的 压力下限信

4、号和变频器的频率下限信号决定，假如压力低，调节器给 PLC 一个 压力下限信号， PLC 启动变频器，并使一号泵处于变频工作状态， 输出的频率 逐渐增大，经过一段时间的调节，如压力还低，这时， PLC 让一号泵处于工频状 态工作，使二号泵处于变频 工作状态泵，如压力还低，则让二号泵处于工频状态 工作， 使三号泵处于变频工作状态， 如此类推。 当压力达到调节器上限报警值时， 调节器输出降低，变频器频率降低，低到频率下限设定值，这时变频器给出一个 频率下限信号给 PLC， PLC 根据先启先停的原则控制泵的运行顺序，例如， PLC 收到频率下限信号时， 系统中泵的状态是一号工频，二号工频，三号变频

5、，这 时一号泵最先启动，所以先停，接着如压力还高，则停二号泵。系统采用了每次 都进行低速启动，高速运行以提高运行效率。 采用变频器 -PLC 恒压供水装置有以下几个 优点： A:节电效益高。传统水泵电机均采用大容量电机，用阀门控制水量恒定，造 成电能浪费。 变频系统，无论工作参数如何，电机的效率不会降低，电机的功率因数会得 到提高。 B:运行可靠、稳定。系统中的核心部件 变频调速器本身的可靠性很高，一般 情况下可连续使用 10 万/h 以上。系统还采用软启动方式，不存在电气冲击，不 污染电网，而且变频器自带欠压、过压、过流、过载、过热以及失速等各种保护 功能。系统对管网压力波动采取阻尼滤波处理

6、，供水恒压精度较高，通常能控制 在 0.002Mpa 范围内。 C:结构 简单，操作简便。装置的控制系统采用集成度高，配套方案灵活多样， 由可编程控制器得到水泵运行的各种组合。调速范围广，对水量变化的适应能力 强。 D:使用寿命长，自动化程度高，无需人看管，维护量少。 以上系统在实际的应用中效果显著， 如将 PLC 与变频器中自带编程器的功能 集成，可开发成一些专用的变频器，这样系统的可靠性与健壮性大大增强，应用 更加简单，系统的总成本也会下降。 可以预见：未来的变频技术会向以下方向发展： (1) 高性能化 包括内部的整流电路、逆变电路都采用高频 PWM 电路从而使输入、输出都 是 正弦波；对

7、于大容量变频器采用多重化和多机并联；降低变频器自身损耗，实 现高效率化；实现自动调谐或自优化、遥控和远控；更加面向用户，进一步提高 可使用性和维修性：向着小型、轻量发展，以及降低成本等。 (2) 智能化 包括两个方面：尽量减少硬件，实现硬件软件化；采用智能电力电子器件 和其他智能化部件。集成化是智能化的基础。 (3) 全数字化 近年来，各种现代控制理论、专家系统、模糊控制及神经元控制等都是发展 的热点，将使电力电子控制技术发展到一个崭新的阶段。预计 21 世纪全数字控 制的应用将更加广泛深入，甚至取代模拟控制 。 (4) 系统化 变频技术的发展与其相关技术的发展是分不开的， 21 世纪变频技术

8、的发 在 展是将电网、整流器、逆变器、电动机、生产机械和控制系统等作为一个整体、 从系统上进行考虑的。 Transducer in the water control system applications Currently, the water level control in a large part of the electrical pumps are not towing gear shift system, no gear shift most of the electrical energy consumed in the water supply to the frequen

9、t changes in the pumps stopped. This not only makes the electrical work in inefficient zones, cut short the useful life of electrical and electrical equipment for the frequent failure to stop the high rate, leading to serious waste of water resources, system maintenance, repairs larger workload. Wit

10、h high living water and industrial water gradually increased, the traditional control methods that are outdated. Originally used for artificial water level control, water level due to the lack of accurate positioning hour monitoring, it is difficult to accurately control the pumps have stopped； Usin

11、g buoys or mechanical control devices such as water supply situation has made some changes, but because of mechanical failure more devices, poor reliability to maintenance will face great trouble. Frequency conversion technology, with its superiority in the area of energy efficiency and Constant Pre

12、ssure control system can be solved by the existence of the above problems. Consider selecting Single Chip Micro controller or PLC and transducer combination at the core of the system can achieve a better control results. But in software design, PLC programming of more than Single Chip Micro controll

13、er concise, and visual； From the hardware interface considerations, Single Chip Micro controller circuit slightly complex； From the economic considerations, the PLC processes are mature, cost and small PLC Single Chip Micro controller a little, because the system parameters to be adjusted in accorda

14、nce with the situation on the ground, PLC software, the time parameters adjustments simpler, so more conducive to after-sale personnel. For the above reasons, the selection of the Omron PLC CPM1 series with the transducer as ABB control core, coupled with PSW7 conditioners and WSP300 Biansongqi pres

15、sure, the effect was very good control, software design simple hardware interface simple and feasible, reliable, the entire system Xingjiebi very high. Transducer in the water system in conjunction with the introduction of small PLC technology not only change the traditional use of water control val

16、ves, and in energy conservation, Constant Pressure control, are very good results, the paper introduced a transducer -PLC control technology in the pump control applications. Control system using one Taiwan transducer can bring three pumps, pumps can work at the frequency pump in the conventional mo

17、del can work in the frequency conversion pump model. At the pump only in frequency conversion or one of the working frequency mode through two relays efficient ensure its security and reliability. System structure as figure 1 shows, the use of placement in the life of water pressure Biansongqi water

18、 pressure signal transmission to the regulator, in accordance with the regulator to set the value and warning of lower compared to send signals to the PLC and the transducer, the system has stopped pumping from regulator pressure level signals and transducer frequency range signal, if the low pressu

19、re, regulator to the PLC a pressure lower signal PLC activation transducer, and a frequency conversion 1st pumps work state, and the output frequency gradually increasing, after a period of adjustment, such as pressure is low, then, PLC for 1st pumps in the frequency of work, 2nd pump frequency conv

20、ersion work at the state pumps, such as pressure is low, 2 pumps at the frequency for the state and make the state 3rd pumps in frequency conversion work, and so on. When the pressure regulator to limit the police on duty, regulator output reduction, transducer frequency reduced to the low frequency

21、 range set value at a given frequency transducer signals to the lower PLC,PLC According to Kai principle pause control pump operation sequence, for example, PLC received lower frequency signals, the system pumps state is the frequency 1st, 2nd-frequency, 3rd frequency conversion, the first time 1st

22、pumps activated, the first stop, then as the pressure was high, then stopped on the 2nd pumps. Each system is used for slow start, high-speed operation in order to enhance operational efficiency. Introduces the frequency changer union small PLC technology in the water supply system, not only change

23、tradition with valve control water volume how many, moreover in aspects and so on energy conservation, constant pressure control had the extremely good effect, this article introduced the frequency changer-PLC regulation technology in water pump control application. The control system may bring thre

24、e water pumps with a frequency changer, each water pump already may work in the conventional power frequency pump pattern, also may work in the frequency conversion pump pattern. Each pump only can be in the frequency conversion or the power frequency one kind of working pattern, guarantees its safe

25、ty and the unreliability mutually through two relay locks. System structure as shown in Figure one, the use places in the domestic water pressure transmitting instrument the water pressure signaling regulator, and reports to the police the bound according to and the regulator setting value to compar

26、e, delivers a letter the number for PLC and the frequency changer, the system stops the pump separately decided by the regulator low pressure limit signal and the frequency changer lower frequency limit signal, if the pressure is low, the regulator for a PLC low pressure limit signal, the PLC start

27、frequency changer, and causes the first pump to be at the frequency conversion active status, the output frequency increases gradually, passes through a period of time adjustment, if the pressure is also low, by now, PLC let the first pump be at the power frequency condition The work, causes the sec

28、ond pump to be at the frequency conversion active status pump, if the pressure is also low, then lets the second pump be at the power frequency condition work, causes the third pump to be at the frequency conversion active status, so analogizes. When the pressure achieved when the regulator upper li

29、mit reported to the police the value, the regulator outputs reduces, the frequency changer frequency reduces, lowers to the lower frequency limit setting value, by now the frequency changer gave a lower frequency limit signal the principle which opened first for the PLC, PLC basis stops first to con

30、trol the pump the movement order, when for example, PLC received the lower frequency limit signal, in the system the pump condition was a power frequency, two power frequencies, three frequency conversion, the first pump first started by now, therefore stopped first, like the pressure also was then

31、high then stopped the second pump. The system used all has each time carried on the low speed to start, the high speed movement enhanced the operating efficiency. Uses the frequency changer - PLC constant pressure water supply installment to have following several merits: A:The electricity saving be

32、nefit is high. The traditional water pump electrical machinery uses the large capacity electrical machinery, is constant with the valve control water volume, creates the electrical energy waste. Frequency conversion system, regardless of the operational parameter how, the electrical machinery effici

33、ency cant reduce, the electrical machinery power factor can obtain the enhancement. B:Moves is reliable, is stable. In the system core part - frequency conversion velometer itself reliability is very high, in the ordinary circumstances may the long-term usage 100,000/Above h. The system also selects

34、 the soft start method, does not have the electrical impact, does not pollute the electrical network, moreover frequency changer bringing owes presses, the pressure, the overflow, the overload, superheat as well as loses speed and so on each kind of protection function. The system adopts damping fil

35、ter processing to the pipe network fluctuation of pressure, the water supply constant pressure precision is high, usually can control in the 0.002Mpa scope. C:The structure is simple, the operation is simple. The installment control system uses the integration rate to be high, necessary plan nimble

36、diverse, obtains water pump movement each kind of combination by the programmable controller. The velocity modulation scope is broad, to water volume change adaptiveness. D:The service life is long, the automaticity is high, does not need the human to safeguard, maintains the quantity to be few. Abo

37、ve system the effect is remarkable in the actual application, if brings in PLC and the frequency changer the programmer the function integration, potential becomes some special-purpose frequency changers, such system reliability and the toughness big enhancement, the application is simpler, the system total cost also can drop. May foresee: The future frequency conversion technology will be able to develop to the below direction: