电气工程及自动化专业英语考试翻译课文Electric Power Systems 电力系统3.1

Section 1 Introduction 第一节介绍
The modern society depends on the electricity supply more heavily than ever before.现代社会比以往任何时候对电力供应的依赖更多。

It can not be imagined what the world should be if the electricity supply were interrupted all over the world. 如果中断了世界各地的电力供应，无法想像世界会变成什么样子Electric power systems (or electric energy systems), providing electricity to the modern society, have become indispensable components of the industrial world. 电力系统（或电力能源系统），提供电力到现代社会，已成为产业界的不可缺少的组成部分。

The first complete electric power system (comprising a generator, cable, fuse, meter, and loads) was built by Thomas Edison –the historic Pearl Street Station in New York City which began operation in September 1882. 托马斯爱迪生建立了世界上第一个完整的电力系统（包括发电机，电缆，熔断器，计量，并加载）它就是位于纽约市具有历史意义的珍珠街的发电厂始于1882年9月运作。

This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly 1.5 km in radius. The load, which consisted entirely of incandescent lamps, was supplied at 110 V through an underground cable system. 这是一个直流系统，由一个蒸汽发动机驱动的直流发电机其供电面积约1.5公里至59范围内的客户。

负载，完全由白炽灯组成，通过地下电缆系统用110v电压供电。

Within a few years similar systems were in operation in most large cities throughout the world. With the development of motors by Frank Sprague in 1884, motor loads were added to such systems.随后几年内，类似的电力系统在世界各地陆续的开始运作，由于法兰克，史博格在1884年研制出电动机，电动机负荷开始接入这类系统This was the beginning of what would develop into one of the largest industries in the world. In spite of the initial widespread use of DC systems, they were almost completely superseded by AC systems. By 1886, the limitations of DC systems were becoming increasingly apparent. They could deliver power only a short distance from generators.
由此开始电力系统逐渐发展成为世界上最大的工业体系之一，尽管直流系统开始广泛使用但后来它们几乎被交流系统取代，到1886年，直流系统的缺点日益明显。

直流系统只能在发电机的短距离范围内输送电力，对于长距离输送电力而言To keep transmission power losses ( I 2 R ) and voltage drops to acceptable levels, voltage levels had to be high for long-distance power transmission. Such high voltages were not acceptable for generation and consumption of power; therefore, a convenient means for voltage transformation became a necessity. 为了将输电损耗（12r）和电压降落控制在可接受的水平，必须采用高的电压，如此高的电压对于发电还是用电都是不可接受的，因此必须有一个方便的电压变换方法
The development of the transformer and AC transmission by L. Gaulard and JD Gibbs of Paris, France, led to AC electric power systems. 法国巴黎的西安·戈拉尔和约翰吉布斯发明了变压器和交流输电方式，交流系统后得到了广泛的应用In 1889, the first AC transmission line in North America was put into operation in Oregon between Willamette Falls and Portland. 1889年，第一条交流输电线路在北美澳洲投入运行，它位于这俩地方之间
It was a single-phase line transmitting power at 4,000 V over a distance of 21 km. With the development of polyphase systems by Nikola Tesla, the AC system became even more attractive. By 1888, Tesla held several patents on AC motors, generators, transformers, and transmission systems. Westinghouse bought the patents to these early inventions, and they formed the basis of the present-day AC systems.这是一个单相线路，输电电压4,000V，输电距离21km。

尼古拉特斯拉发明了多项输电系统后，交流输电系统变得更有优势，到1888年，拥有了交流电动机，发电机，变压器和输电系统等多项技术专利。

威斯丁豪斯公司购买了这些早期的发明专利，这些专利为当今的交流电力系统奠定了基础
In the 1890s, there was considerable controversy over whether the electric utility industry should be standardized on DC or AC. By the turn of the century, the AC system had won out over the DC system for the following reasons: 在19世纪90年代，有很大的争议或交流电力行业是否应该统一于直流。

到了世纪之交的，在交流系统赢得了原因出在下面的直流系统为：
（1）V oltage levels can be easily transformed in AC systems, thus providing the flexibility for use of different voltages for generation, transmission, and consumption.在交流系统中可以方便的实现了电压等级的交换从而实现了在不同电压的水平发电输电用电的灵活性
（2）AC generators are much simpler than DC generators. （2）交流发电机比直流发电机简单得多
（3）AC motors are much simpler and cheaper than DC motors. （三）交流电机和电机便宜简单便宜的多。

The first three-phase line in North America went into operation in 1893——a 2,300 V, 12 km line in southern
California. 南加州第一条三相交流输电线路投产于1893年开始运行。

它位于南家福尼亚2300v电线长度12km In the early period of AC power transmission, frequency was not standardized. 在交流输电的早期阶段，频率没有实现标准化。

Many different frequencies were in use: 25, 50, 60, 125, and 133 Hz. 有许多不同频率曾被使用：25，50，60，125，和133赫兹。

This poses a problem for interconnection. Eventually 60 Hz was adopted as standard in North America, although 50 Hz was used in many other countries.这给系统之间相互连接带来了问题，最终北美将60赫兹定为标准频率‘50赫兹在许多其他国家使用。

The increasing need for transmitting large amounts of power over longer distance created an incentive to use progressively high voltage levels. 日益增长的对远距离大容量电能输送的需求促进了输电电压等级的逐渐提高To avoid the proliferation of an unlimited number of voltages, the industry has standardized voltage levels. In USA, the standards are 115, 138, 161, and 230 kV for the high voltage (HV) class, and 345, 500 and 765 kV for the extra-high voltage (EHV) class. In China, the voltage levels in use are 10, 35, 110 for HV class, and 220, 330 (only in Northwest China) and 500 kV for EHV class . 为了避免电压等级无限制的扩散，电压行业对电压等级行业实现了标准化。

在美国，高电压标准是115，138，161，和230千伏的（高压），345，500和765千伏级的特高电压（超高压）。

在中国，各级使用电压为10，35，110级高压，220，中国330（仅在西北）和500千伏超高压类。

The first 750 kVtransmission line will be built in the near future in Northwest China. 第一个750 kVtransmission线将建在不久的将来在中国西北地区。

With the development of the AC/DC converting equipment, high voltage DC (HVDC) transmission systems have become more attractive and economical in special situations. 随着交流的发展/直流转换设备，高压直流高压直流（HVDC）传输系统已经成为更具吸引力的经济和优势。

The HVDC transmission can be used for transmission of large blocks of power over long distance, and providing an asynchronous link between systems where AC interconnection would be impractical because of system stability consideration or because nominal frequencies of the systems are different. HVDC可用于远距离大容量输电，也可用于交流输电系统之间的异步联网。

因为交流系统之间可能由于稳定问题或额定频率不同而不能实现交流联网
The basic requirement to a power system is to provide an uninterrupted energy supply to customers with acceptable voltages and frequency. 对于电力系统的基本要求是以可接受的电压和频率给用户提供一个不间断的能源供应（，以客户可接受的电压和频率）。

Because electricity can not be massively stored under a simple and economic way, the production and consumption of electricity must be done simultaneously. A fault or misoperation in any stages of a power system may possibly result in interruption of electricity supply to the customers. 由于电力无法大量储存在一个简单的方法和经济，电力的生产和消费必须同时进行。

系统的故障或误操作的权力在任何阶段可能导致电力供应中断给客户。

Therefore, a normal continuous operation of the power system to provide a reliable power supply to the customers is of paramount importance. 因此，一个正常的电力系统连续运行的，提供可靠的电力供应给客户的重要性是至关重要的。

Section2
Modern power systems are usually large-sare,geographically distributed, and with hundreds to thousands of generators operating in parallel and synchronously. 现代电力系统通常规模大，地域分布广，有成百上千的发电机组并列同步运行。

They may vary in size and strncture from one to another,but they all have the same basic characteristics 电力系统之间的大小和结构可能有所不同，但它们的基本特征相同
（1）Are comprised of three-phase AC systems operating essentially at constant voltage.由在恒定电压下运行的三相交流系统组成。

Generation and transmission facilities use three-phase equipment . 发电和输电设施使用三相设备。

Industrial loads are invariablythree-phase; single-phase residential and commercial loads are distributed equally among the phases so as to effectively form a balanced three-phase system. 工业负荷采用三相式，为了组成一个平衡的三相系统单相的居民和商业负荷平均的分配在三相系统的各项上
(2)Use synchronous machines for generation of electricity. 采用同步发电机发电Prime movers convert the primary energy (fossil, nuclear, and hydraulic) to mechanical energy that is, in turn, converted to electrical energy by synchronous generators.原动机将一次能源转化为机械能，然后由同步发电机将机械能转化为电能
（3）Transmit power over significant distances to consumers spread over a wide area. This requires a transmission system
comprising subsystems operating at different voltage levels.在广阔的区域上通过长距离给用户送电，这就要求输电系统必须由运行在不同电压等级上的子系统组成
The basic elements of a modern power system in USA are shown in Fig.6-1. Electric power is produced at generating stations (GS) and transmitted to consumers through a complex network of individual components, including transmission lines, transformers, and switching devices.在美国，现代电力系统的基本组成部分由图6-1显示，电能由发电厂生产出来，并通过一个由独立元件组成的复杂网络送给用户，这些元件包括：输电线路，变压器和开关设备等It is common practice to classify the transmission network into the following subsystems: Transmission system; Subtransmission system; Distribution system. 通常的做法是把输电网络分类为下列的子系统：输电系统；次级输电系统和配电系统。

The transmission system interconnects all major generating stations and main load centers in the system. 输电系统highest voltage levels (typically, 230 kV and above in USA).输电系统组成了整个电力系统骨架，并运行在最高的电压等级（在美国典型电压为230kv及以上）The generator voltages are usually in the range of 11 to 35 kV. 发电机的电压范围通常在11至35千伏。

These are stepped up to the transmission voltage level, and power is transmitted to transmission substations where the voltages are stepped down to the subtransmission level (typically, 69 to 138 kV).将发电机电压升到输电系统电压水平，电能由输电系统送到输电变压器在输电变电站内电压被降到二次输电系统的电压水平（典型电压为69- 138kv）。

The generation and transmission subsystems are often referred to as the bulk power system. 发电和传输子系统通常被叫做主干电力系统。

The transmission system transmits power in small quantities from the transmission substations to the distribution substations.二次输电系统将较小容量的电能由输电变电站送到配电变电站large industrial customers are commonly supplied directly from the subtransmission system.大的工业用户通常在二次输电系统直接供电In some systems,there is no clear demarcation between subtransmission and transmission ciruits在某些系统中，二次输电系统和输电系统之间没有明确的界限. As the system expands and higher voltage levels become necessary for transmission ,由于系统的扩展和更输电压的采用the order transmission lines are often relegated to subtransmission funcition.老的输电线路通常降级使用来担负二次输电功能
The distribution system represents the final stage in the transfer of power to the individual customers. The primary distribution voltage is typically between 4.0 kV and 34.5 kV. V.配电系统将电能传输到用户的最后一级，典型的配电电压在4。

0-34·5kv之间，Small industrial customers are supplied by primary feeders at this voltage level. The secondary distribution feeders supply residential and commercial customers at 120/240小的工业用户由这个电压等级上的一次馈线来供电，二次配电馈线在120/240v电压上给居民和商业用户来供电
Small generating plants located near the load are also connected to the subtransmission or distribution system directly靠近负荷的小型发电厂也可能直接接入二次输电系统或配电系统，. Interconnections to neighboring power systems are usually formed at the transmission system level. 相邻系统之间的互馈通常在输电系统层次上进行，整个系统从而由多个电源和多层输电网络组成。

The overall system thus consists of multiple generating sources and several layers of transmission networks. This provides a high degree of structural redundancy that enables the system to withstand unusual contingencies without service disruption to the customers.这种组成方案提供了一个结构上的冗余度，使系统能够抵抗一些异常的事故而不至于中断对用户的供电
++Power system stability may be broadly defined as the property of a power system that enables it to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a disturbance. 电力系统稳定，可广泛定义为干扰财产的权力系统，可继续经营的状态下正常运行的平衡条件和后向遭受恢复一个可以接受的平衡状态。

Instability in a power system may be manifested in many different ways depending on the system configuration and operating mode. 在电力系统的不稳定可能会表现在经营方式和多种不同的方式取决于系统配置。

Traditionally, the stability problem has been one of maintaining synchronous operation. Since power systems rely on synchronous machines for generation of electrical power, a necessary condition for satisfactory system operation is that all synchronous machines remain in synchronism or, colloquially "in step". This aspect of stability is influenced by the dynamics of generator rotor angles and power-angle relationships, and then referred to " rotor angle stability ". 传统上，稳定性问题一直是一个保持同步运行。

由于电力系统的发电电力，一个令人满意的系统运行的必要条件是，依靠同步电机同步电机都留在同步或通俗的“步骤”。

这一方面是受稳定的发电机转子的动态角度和功角的关系，然
后提到“转子角稳定”。