电气专业英语翻译

第八章

第一节燃煤发电厂

在化石燃料电厂中 煤 石油和天然气在炉内燃烧 燃烧产生的热能将水加热并把它转化为蒸汽 蒸汽用来驱动与发电机机械耦合的涡轮机。典型燃煤发电厂的示意图如图8-1所示。将发电厂的运行过程简单描述如下。煤从储煤场取出后送入磨煤机 从磨煤机出来的煤粉与预热过的空气混合后吹入炉内燃烧。包含一套复杂管道和汽包的炉子叫做锅炉 水泵将水送入锅炉 在锅炉内 水的温度上升直到蒸发成蒸汽。蒸汽流向涡轮机 燃烧烟气在送入机械和静电除尘器除去99%的固体颗粒 灰 后派往烟囱。上面描述的以煤粉 空气和水作为输入以蒸汽作为输出的单元可以叫做蒸汽发生单元 锅炉或蒸发器。当考虑燃烧过程时 常用术语“锅炉” 而考虑水—汽循环时 常用“蒸发器”一词。典型压力为3500psi 温度为1050度F的蒸汽通过关断阀门和控制阀门送给汽轮机 蒸汽的热能由汽轮机转化为机械能。从汽轮机出来的乏汽在一个叫做“冷凝器”的热交换器内冷却 然后作为给水再次送回锅炉。控制阀门允许汽轮发电机组通过调节蒸汽流量而改变输出功率。关断阀门起一个保护作用 正常时它是全开的 如果电气输出功率突然降低 由于断路器动作 他可以突然关断以防止汽轮发电机超速 但此时控制阀门不关闭。图8-1所示为“单级”汽轮机 但实际中采用更为复杂的“多级”布置以获得相对高的热效率。图8-2所示为代表性的“多级“布置汽轮机示意图。在这个多级布置中 四个蒸汽压力不同的涡轮机在机械以级联的排列形式连接在一起。在惯常的的流程中 从锅炉 过热器 出来的高压蒸汽进入高压 HP 缸。蒸汽从高压缸出来被送回锅炉的再热器 然后送入中压 IP 缸。蒸汽离开中压缸后 压力很低体积膨胀很大 被送入低压 LP 缸。从低压缸出来的乏汽在冷凝器中被冷却 然后作为锅炉给水用从汽轮机中抽出的蒸汽预热后 通过给水泵送回锅炉。燃煤发电厂的净效率通常低于40% 也就是煤的化学能转化成电能的比例低于40% 。尽管这个数字与大约30%的工业平均值相比具有一定的优越性 但是超过60%的化石燃料能量被转化为废热。

为了提高效率和节约一次能源 热电联产系统被长期采用 这种系统可以同时生产电能 用于工业用途或室内加热的蒸汽。在这种系统中 总能量效率已高达60%~65%。与燃煤电

厂相关的一些问题是煤的开采与运输带来的安全危害和其他社会成本。燃煤电厂与其他类型化石燃料电厂共同产生的环境问题包括酸雨和温室效应。

第6章(6)-3)

Section 3 Operation and Control of Power Systems 第3节操作和控制的电力系统The purpose of a power system is to deliver the power the customers require in real time, on demand, within acceptable voltage and frequency limits, and in a reliable and economic manner. 该系统的目的，权力是为客户提供电力的时间为客户需要实际需求，对，在可接受的电压和频率的限制，在一个可靠和经济的方式。In normal operation of a power system, the total power generation is balanced by the total load and transmission losses. 在电力系统正常运行的，总发电是平衡的总负荷和传输的损失。The system frequency and voltages on all the buses are within the required limits, while no overloads on lines or equipment are resulted. 该系统的频率和电压的所有公共汽车都在规定的限额，而没有超载或设备上线造成的。However, loads are constantly changed in small or large extents, so some control actions must be applied to maintain the power system in the normal and economic operation state. 但是，负载不断变化幅度小或大，所以一些控制行动必须适用于维持在正常和经济运行状态的电力系统。Optimal economic operation 优化经济运行It is an important problem how to operate a power system to supply all the (complex) loads at minimum cost. 这是一个重要的问题如何操作电源系统，以提供所有的负载以最低的成本（复杂）。The basic task is to consider the cost of generating the power and to assign the allocation of generation ( P Gi) to each generator to minimize the total "production cost" while satisfying the loads and the losses on the transmission lines. 其基本任务是考虑发电成本的生成和分配产生的分配性（P基）每个发电机，以尽量减少总的“生产成本”，同时满足负载和传输线路上的损失。The total cost of operation includes fuel, labor, and maintenance costs, but for simplicity the only variable costs usually considered are fuel costs. The fuel-cost curves for each generating unit are specified, the cost of the fuel used per hour is defined as a function of the generator power output. When hydro-generation is not considered, it is reasonable to choose the PGi on an 总的经营成本，包括燃料，劳动和维修费用，但只有简单的可变成本通常被认为是燃料成本。曲线每个机组的燃料成本是指定的，时间成本占燃料使用的是输出功率定义为一个函数的发电机。当水文一代是不考虑它是合理的选择上一的PGI instantaneous basis (ie always to minimize the present production cost rate). 瞬间的基础上（即始终以减低目前的生产成本率）。With hydro-generation, however, in dry periods, the replenishment of the water supply may be a problem. 随着水电发电，但是，在干燥的时期，供应补给的水可能是个问题。The water used today may not be available in the future when its use might be more advantageous. Even without the element of the prediction involved, the problem of minimizing production cost over time becomes much more complicated. 今天使用的可能不会在将来提供其使用时，可能会更有利的水。即使没有参与预测的元素，最大限度地减少生产成本的问题变得更加复杂。It should be mentioned that economy of operation is not the only possible consideration. 应当提及的是经济运行的不是唯一可能的考虑。If the "optimal" economic dispatch requires all the power to be imported from a neighboring utility through a single transmission link, considerations of system security might preclude that solution .

如果在“最佳”的经济调度要求所有的权力，是从邻国进口的效用，通过一个单一的传输链路，系统安全的考虑可能会排除这种解决办法。When water used for hydro-generation is also used for irrigation, nonoptimal releases of water may be required. Under adverse atmospheric conditions it may be necessary to limit generation at certain fossil-fuel plants to reduce emissions. 当水发电用于水力发电也用于灌溉，水nonoptimal释放可能是必要条件。不良大气下它可能需要限制某些植物代化石燃料，以减少排放。In general, costs, security and emissions are all areas of concern in power plant operation, and in practice the system is operated to effect a compromise between the frequently conflicting requirements. 一般而言，成本，安全和排放装置运行一切权力领域关注，并在实践中系统的运作产生影响，要求折衷之间经常发生冲突。Power system control 电力系统控制Power system control is very important issue to maintain the normal operation of a system. 电力系统的控制是很重要的问题，以维持系统的正常运行。System voltage levels, frequency, tie-line flows, line currents, and equipment loading must be kept within limits determined to be safe in order to provide satisfactory service to the power system customers. 系统电压水平，频率，联络线流，线电流和设备装载必须保持确定的限度内是安全的，以提供满意的服务，电力系统的客户。Voltage levels, line currents, and equipment loading may vary from location to location within a system, and control is on a relatively l ocal basis. 电压等级，线路电流和设备负荷可能不同地点间的系统内，控制相对升厄恰尔基础上。For example, generator voltage is determined by the field current of each particular generating unit; however, if the generator voltages are not coordinated, excess var flows will result. Similarly, loading on individual generating units is determined by the throttle control on thermal units or the gate controls on hydro-units. Each machine will respond individually to the energy input to its prime mover. Transmission line loadings are affected by power input from generating units and their loadings, the connected loads, parallel paths for power to flow on other lines, and their relative impedances. 例如，发电机电压是由该领域目前的每一个具体单位产生，但是，如果发电机电压不配合，无功流量将过剩的结果。同样，对个别单位负荷发电，是由热量单位或确定的控制油门水文单位的大门管制。每台机器回应个别的能量投入到其原动力。输电线路荷载的影响，输入功率发电机组和他们的负荷，连接的负载，其他电力线平行的道路上流动以及其相对阻抗。Active power and frequency control 有功功率和频率控制For satisfactory operation of a power system, the frequency should remain nearly constant. Relatively close control of frequency ensures constancy of speed of induction and synchronous motors. Constancy of speed of motor drives is particularly important for satisfactory performance of all the auxiliary drives associated with the fuel, the feed-water and the combustion air supply systems. In a network, considerable drop in frequency could result in high magnetizing currents in induction motors and transformers . 对于电力系统运行合格的，频率应该保持几乎不变。较为密切的保证电动机变频调速同步恒定速度感应和。驱动电机转速恒定，尤其是在重要的关联的所有辅助驱动器的表现令人满意燃料，饲料，水和空气供给系统燃烧。在网络，大幅下降的频率可能会导致电机和变压器激磁电流的高感应。The extensive use of electric clocks and the use of frequency for other timing purpose require accurate maintenance of synchronous time which is proportional to integral of frequency. As a consequence, it is necessary to regulate not only the frequency itself but also its integral. The frequency of a system is dependant on active power balance. As frequency is a common factor throughout the system, a change in active power demand at one point is reflected throughout the system by a change in frequency. 广泛使用的电动时钟和定时的目的使用的频率为其他需要作为一个同步时间是成正比的积分。结果准确的频率维持，它是要规范，不仅本身的频率，

而且它的积分。该系统是一个频率依赖于积极的力量平衡。由于频率是1点共同的因素在整个系统，有源电力需求的变化是反映整个系统的频率变化。Because there are many generators supplying power into the system, some means must be provided to allocate change in demand to the generators. A speed governor on each generating unit provides the primary speed control function, while supplementary control originating at a central control center allocates generation. In an interconnected system with two or more independently controlled areas, in addition to control of frequency, the generation within each area has to be controlled so as to maintain scheduled power interchange. The control of generation and frequency is commonly referred to as load-frequency control (LFC). 在一个相互联系的系统控制区的两个或两个以上独立此外，在控制的频率，在每个地区的一代已被控制，以保持计划的权力交换。的生成控制和频率通常被称为频率为负载控制（消失模）。The control measures of power and frequency include: 功率和频率的控制措施包括：（1）Regulation of the generator's speed governor （1）总督调节发电机的速度（2）Underfrequency load shedding （2）低频减载（3）Automatic generation control (AGC) （3）自动发电控制（AGC）AGC is an effective means for power and frequency control in large-scale power systems. 大型电力系统AGC的是一个有效的手段功率和频率控制大。In an interconnected power system, the primary objectives of AGC are to regulate frequency to the specified nominal value and to maintain the interchange power between control areas at the scheduled values by adjusting the output of the selected generators. This function is commonly referred to as load-frequency control . 在一个相互联系的电力系统，自动增益控制的主要目的是调节频率到指定的名义价值，并保持在预定值，通过调整所选发电机输出控制区之间的交换能力。这个函数通常被称为负载频率控制。A secondary objective is to distribute the required change in generation among units to minimize operating costs. 第二个目标是改变单位之间分配在一代人的需要，以减低经营成本。In an isolated power system, maintenance of interchange power is not an issue. Therefore, the function of AGC is to restore frequency to the specified nominal value. This is accomplished by adding a reset or integral control which acts on the load reference setting of the governors of unit on AGC. 在一个孤立的电力系统，电力维修转乘不是一个问题。因此，AGC功能是恢复到指定的频率标称值。这是通过增加一个或积分复位控制于负载上的AGC的机组省长设置参考行为。The integral control action ensures zero frequency error in the steady state. The supplementary generation control action is much slower than the primary speed control action. As such it takes effect after the primary speed control (which acts on all units on regulation) has stabilized the system frequency. Thus, AGC adjusts load reference settings of selected units, and hence their output power, to override the effects of the composite frequency regulation characteristics of the power system .积分控制作用的保证零稳态频率误差英寸补充发电控制行动的动作比主慢速度控制。因此，它需要具有效力后的首要速度控制（对所有单位的行为，对监管）稳定的系统频率。因此，AGC的机组负荷调整选定的参考设置，因此它们的输出功率，覆盖电力系统的影响，复合材料的频率调节特性。In so doing, it restores the generation of all other units not on AGC to scheduled values. 在这样做时，没有恢复的AGC所有其他单位代定值。Reactive power and voltage control 无功功率和电压控制For efficient and reliable operation of power systems, the control of voltage and reactive power should satisfy the following objectives: 为了有效和可靠的电力系统运行的目标，在控制电压和无功功率，应符合下列条件：（1）Voltages at the terminals of all equipment in the system are within acceptable limits. （1）系统电压的所有终端设备，在可接受的限度内。Both utility equipment and customer equipment are designed to operate at a certain voltage rating. 这两种

工具设备和客户设备的设计运行在一定的电压等级。Prolonged operation of the equipment at voltages outside the allowable range could adversely affect their performance and possibly cause them damage. 该设备在长期运行电压允许范围以外的可能影响其性能，并可能导致他们的伤害。（2）System stability is enhanced to maximize utilization of the transmission system. （2）提高系统的稳定性，以最大限度地提高系统利用率的传输。（3）The reactive power flow is minimized so as to reduce RI2 and XI2 losses to a practical minimum. （3）无功功率流最小化，以减少RI2和XI2实际损失减至最低。This ensures that the transmission system operates efficiently, ie mainly for active power transfer. 这确保了传输系统的运作效率，即转让主要是积极的力量。The problem of maintaining voltages within the required limits is complicated by the fact that the power system supplies power to a vast number of loads and is fed from many generating units. As loads vary, the reactive power requirements of the transmission system vary. Since reactive power can not transmitted over long distances, voltage control has to be effected by using special devices dispersed throughout the system. This is in contrast to the control of frequency which depends on the overall system active power balance.问题所需的限度内保持电压是复杂的是，电力系统提供电源的负载数量庞大，而且是从许多单位产生厌倦。由于负载不同，输电系统的无功需求各不相同。由于反应权力不能传输的距离长，电压控制，必须使用特殊设备实施分散在整个系统。这种平衡是相对于频率的控制依赖于整体的系统的积极力量。正确的选择和设备的协调The proper selection and coordination of equipment for controlling reactive power and voltage are among the major challenges of power system engineering. 正确的选择和控制无功功率和电压的设备之间的协调，电力系统的工程的重大挑战。The control of voltage levels is accomplished by controlling the production, absorption, and flow of reactive power at all levels in the system. The generating units provide the basic means of voltage control; the automatic voltage regulators control field excitation to maintain a scheduled voltage level at the terminals of the generators. Additional means are usually required to control voltage throughout the system. The devices used for this purpose may be classified as follows: 水平控制电压是通过控制生产，吸收，无功和功率流在系统各级英寸的发电机组提供了电压控制的基本手段;自动电压调节器控制励磁电压，以保持预定的水平在码头的发电机。通常需要额外的手段来控制整个系统的电压。这些器件用于此目的，可分为下列几类：（1）Sources or sinks of reactive power, such as shunt capacitors, shunt reactors, synchro- nous condensers, and static var compensators (SVCs). （1）资料来源或无功功率汇，如并联电容器，电抗器，同步奴斯冷凝器和静态2004/12）无功补偿器（。（2）Line reactance compensators, such as series capacitors. （2）补偿电容器电抗线，如系列。（3）Regulating transformers, such as tap-changing transformers and boosters. （三）调压变压器的助推器，如调压变压器和。Shunt capacitors and reactors, and series capacitors provide passive compensation. They are either permanently connected to the transmission and distribution system, or switched. 并联电容器和电抗器，电容器，并提供一系列的被动赔偿。他们要么永久连接到传输和分配系统，或切换。They contribute to voltage control by modifying the network characteristics. Synchronous condensers and SVCs provide active compensation, the reactive power absorbed/supplied by them is automatically adjusted so as to maintain voltages of the buses to which they are connected. Together with the generating units, they establish voltages at specific points in the system. Voltages at other locations in the system are determined by active and reactive power flows through various circuit elements, including the passive compensating devices. 电压控制通过修改网络特性。同步冷凝器和2004/12积极提供补偿，无功功率吸收/他们提供的是自动调整，以维持巴士电压的它们所连接的设备。连同生成，他们建立电压

在特定的点在系统中。电压在系统的其他地点取决于有功，无功流经各种电路元件，包括无源补偿装置。三。翻译成中文以下When two or more synchronous machines are interconnected, the stator voltages and currents of all the machines must have the same frequency and the rotor mechanical speed of each is synchronized to this frequency. Therefore, the rotors of all interconnected machines must be in synchronism. In a generator, the electromagnetic torque opposes rotation of the rotor, so that mechanical torque must be applied by the prime mover to sustain rotation. 当两个或多个同步电机是相互联系，定子电压和电流的所有机器必须具有相同的频率和转子的机械速度同步每到这个频率。因此，互联机转子所有必须同步。在一台发电机，电磁转矩转子旋转的反对，使机械扭矩必须由总理先行者申请维持旋转。The electrical torque ( or power ) output of the generator is changed only by changing the mechanical torque input by the prime mover. 电气力矩（或功率）发电机的输出是通过改变只改变了原动机的机械转矩输入。The effect of increasing the mechanical torque input is to advance the rotor to a new position relative to the revolving magnetic field of the stator. Conversely, a reduction of mechanical torque or power input will retard the rotor position. In a synchronous motor, the roles of electrical and mechanical torques are reversed compared to those in a generator.输入的影响是增加了机械扭矩推进到一个新的转子相对位置的定子旋转磁场。反过来，一个或减少机械扭矩输入功率会阻碍转子的位置。在同步电机，机械力矩的作用是相反的电气和发电机相比，那些在1。

第三节第三节第三节第三节欧姆定律欧姆定律欧姆定律欧姆定律用来模拟

材料阻流性能的电路元件是电阻，电阻是最简单的无源元件。德国物理学家乔治西蒙欧姆（1787～1854），1826年根据实验提出电阻的电流——电压关系，为此而享誉世界。这一关系被称为欧姆定律。欧姆定律表明电阻器两端的电压正比于流过电阻器的电流。这个比例常值就是该电阻器以欧姆为单位的电阻值。电阻器的电路符号如图1－8所示。对于所示的电流和电压，欧姆定律就是把方程（1－9）重新整理为的形式，我们将看到：1ohm＝1V/A 用来表示欧姆定律的方程（1－9）是一个直线方程，由于这个原因，电阻就被称为线性电阻。u（t）相对于i（t）而变化的图形，如图1－9所示。它是一条通过原点斜率为R的直线，显然，当u（t）与i（t）的比值对于所有的i（t）都为一恒定值时，其唯一可能的图形就是一条直线。对于不同端部电流而具有不同电阻的电阻器被称为非线性电阻器。对于这种电阻器，电阻就等于器件中所流动的电流的函数。非线性电阻器的一个简单的例子是白炽灯。这种器件的一个典型的伏——安特性曲线如图1－10所示。图中我们看到其图形不再是一条直线。由于它不是一个恒值，对于包含有非线性的电路的分析显得更加困难。事实上，所有实际电阻器都是非线性的，因为所有电阻器的电气性能会受到例如温度等的环境因素所影响。不过很多材料在规定的工作范围内非常接近理想线性电阻。专注于这种类型的元件并且仅仅把它们称为电阻器。由于R值可以从0变化到无穷大，所以对我们来说研究两种极限可能的R值很重要的。具有R＝0的元件称为短路，如图1－11（a）所示。对于短路来说上式显示电压为0而电流可以是任何值。实际上，短路通常是指一段假设为理想导体的连接导线。于是，短路就是电阻近似为0的电路元件。类似地，具有R＝∞的元件被称为开路，如图1－11（b）所示，对于开路来说上式表明电流为0，虽然电压可以是任意值。于是，开路就是电阻近似为无穷大的电路元件。在电路分析中另一个有用的重要电量，被称为电导，定义为()()utRit= ()()utRit=?(1?9)uRi=?(1?10)limRuiR→∞= (1?11)1iGRu== (1?12)

电导是对某一元件传导电流的容易程度的一种度量，电导的单位是西门子。