电力高压电网论文英文文献

Page1. The Production of Electrical Energy(电能生产) testFrom reference 1In large steam power plants, the thermal energy stored in steam is converted into work by means of turbines. A turbine consists essentially of a shaft or rotor fixed in bearings and enclosed in a cylindrical casing. The rotor is made to turn smoothly by means of jets of steam from nozzles around the periphery of the turbine cylinder. These steam jets strike blades attached to the shaft. Central power stations employ condensing turbines in which the steam passes into a condenser after leaving the turbine. Condensation is effected by the circulation of large quantities of cold water through the tubes of the condenser, thus increasing the expansion ratio of the steam and the consequent efficiency and work output of the turbine. the turbines are connected directly to large electricity turbines the action of the steam is kinetic. There is progressive expansion of the steam from the high pressure and relatively small volume at which it enters the turbine to the low pressure and relatively very great volume at which it is made by heating water in a boiler. The usual boiler has a furnace in which fuel is burned and the heat given off during combustion is conducted through the metal walls of the boiler to generate steam at a pressure within the boiler vessel .In nuclear plants, steam is generated with the aid of a reator in which the controlled fission of uranium or plutonium supplies the necessary heat for the vaporization of water. Thus the reator replaces the steam generator of conventional ：turbine, steamFrom reference 2Up until now we have been mainly concerned with minimizing the cost of operating a power system. An overriding factor in the operation of a power system is the desire to maintain system security. System security involves practices designed to keep the system operating when components fail. For example, a generating until may have to be taken off-line because of auxiliary equipment failure. By maintaining proper amounts of spinning reserve, the remaining units on the system can make up the deficit without too low a frequency drop or need to shed any load. Similarly, a transmission line may be damaged by a storm and taken out by automatic relaying. If in committing and dispatching generation proper regard for transmission flows is maintained, the remaining transmission lines can take the increased loading and still remain within limit. Because the specific times at which initiating events that cause components to fail are unpredictable the system must be operated at all times in such a way that the system will not be left in dangerous condition should any credible initiating event occur. Since power system equipment is designed to be operated within certain limits, most pieces of equipment are protected by automatic devices that can cause equipment to be switched out of the system if these limits are violated. If any event occurs on a system that leaves it operating with limits violated, the event may be followed by a series of further actions that switch other equipment out of service. This is usually referred to as a system ：power system, securityFrom reference 3System monitoring provides the operators of the power system with pertinent up-to-date information on the conditions on the power system .Generally speaking it is the most important function of the three. From the time that utilities went beyond systems of one unit supplying a group of loads, effective operation of the system required that critical quantities be measured and the values of the measurements be transmitted to a central location. Such systems of measurement and data transmission, called telemetry systems, have evolved to schemes that can monitor voltages, currents, power flows, and the status of circuit breakers switches in every substation in a power system transmission network. In addition, other critical information such as frequency, generator unit outputs and transformer tap positions can also be telemetered. With so much information telemetered simultaneously, no human operator could hope to check all of it in a reasonable time frame. For this reason, digital computers are usually installed in operations control centers to gather the telemetered data, process them, and place them in a data base from which operators can display information on large display monitors. More importantly, the computer can check incoming information against prestored limits and alarm the operators in the event of an overload or out-of-limit voltage. State estimation is often used in such systems to combine telemetered system data with system models to produce the best estimate (in a statistical)of the current power system conditions or “state”.Keywords：telemeter, estimateFrom reference 4The main objective of production control in power system is to minimize the cost of generated power while maintaining its quality and satisfying the system security constraints. This implies directly that losses in both the generation and the transmission of electrical energy must be as small as possible. All participating generators are run at high efficiencies, the mix of production resources is exploited economically and the energy is transmitted optimally. Production control includes general both active and reactive power. However, the main interest in this type of application has so far been focused mainly on the active part. This is the case in this section also. However, interest for the reactive part is rapidly growing and will soon get a great deal of action. The activities in the production control field have traditionally been based on planning. This is still the case. The aim is then to break down the overall objective into detailed plans, normally on an hourly basis, that can be carried out by the operator in the control center. Thus, several steps are taken in a hierarchical scheme to support the operator’s ambition always to have production resources available to meet the load demand and guide him to operate the generating units so that the most economic alternatives are chosen. The security aspects must also be consisted ,. the selection of production units must not result in line overloads, too high bus voltage etc. If the system suffers the sudden loss of generation, it must be prevented from getting into the alert state for example by activating production reserves. Keywords：production control, security

Page1。生产电能(电能生产) 1。英语考试 文献[1]从 在大型蒸汽发电厂、热能量储存在蒸汽转化为工作通过涡轮机。涡轮由转子轴或基本固定在轴承及封闭在圆筒状的容器中。转子是由通过平滑地转弯的喷射蒸汽从喷嘴周围的涡轮式气缸。这些蒸汽飞机上罢工叶片轴上。中央电站雇用冷凝涡轮机中,蒸汽通过成为一个冷凝器下班后的涡轮机。凝结循环影响大量的冷水通过管冷凝器,从而增加了蒸汽膨胀率,以及由此而导致的效率和工作输出的涡轮式。放置涡轮机直接联到大型电力发电机。 在涡轮机的蒸汽的作用动力学。有进步的扩张的高压蒸汽和相对体积小,进入汽轮机低压力和相当大水量对它的叶子。 蒸汽是通过加热锅炉中的水。通常的锅炉有炉在哪种燃料燃烧热量燃烧过程中的放出经手金属墙在产生蒸汽锅炉压力容器在锅炉在核能,根据蒸汽reator的帮助的铀和钚的分裂控制提供了必要的热,蒸发的水。因此,reator取代蒸汽发生器传统的植物。 关键词:涡轮机中,蒸汽 在参考2 到目前为止我们已经主要涉及的成本最小化操作电力系统。压倒一切的因素电力系统的操作就是希望保持系统的安全。系统安全涉及到实践设计来防止该系统运行当组件失败。例如,一个产生unt