水利水电工程毕业设计外文翻译-桥梁设计(编辑修改稿)

水利水电工程毕业设计外文翻译-桥梁设计(编辑修改稿)内容摘要：

n the electricity generated is called hydroelectric power. This scheme is known as hydro scheme, and the power house is known as hydel power station or hydroelectric power station. In a hydro scheme, a certain quantity of water at a certain potential head is essentially made to flow through the turbines. The head causing flow runs the turbine 西华大学外文资料翻译 4 blades, and thus producing electricity from the generator coupled to turbine. In this chapter, we are concerned with hydel scheme only. 2 classification of hydel plants Hydroplants may be classified on the basis of hydraulic characteristics as follow: ① runoff river plants。 ② storage plants。 ③ pumped storage plants。 ④ tidal plants. they are described below: (1) Runoff river plants. These plants are those which utilize the minimum flow in a river having no appreciable pondage on its upstream side. A weir or a barrage is sometimes constructed across a river simply to raise and maintain the water level at a predetermined level within narrow limits of fluctuations, either solely for the power plants or for some other purpose where the power plant may be incidental. Such a scheme is essentially a low head scheme and may be suitable only on a perennial river having sufficient dry weather flow of such a magnitude as to make the development worthwhile. Runoff river plants generally have a very limited storage capacity, and can use water only when it es. This small storage capacity is provided for meeting the hourly fluctuations of load. When the available discharge at site is more than the demand (during offpeak hours ) the excess water is temporarily stored in the pond on the upstream side of the barrage, which is then utilized during the peak hours. he various examples of runoff the river pant are: Ganguwal and Kolta power houses located on Nangal Hydel Channel, Mohammad Pur and Pathri power houses on Ganga Canal and Sarda power house on Sarda Canal. The various stations constructed on irrigation channels at the sites of falls, also fall under this category of plants. (2) Storage plants A storage plant is essentially having an upstream storage reservoir of sufficient size so as to permit, sufficient carryover storage from the monsoon season to the dry summer season, and thus to develop a firm flow substantially more than minimum natural flow. In this scheme, a dam is constructed across the river and the power house may be located at the foot of the dam such as in Bhakra, Hirakud, Rihand projects etc. the power house may sometimes be located much away from the dam (on the downstream side). In such a case, the power house is located at the end of tunnels which carry water from the reservoir. The tunnels are connected to the power house machines by means of pressure penstocks which may either be underground (as in Mainthon and Koyna projects) or may be kept exposed (as in Kundah project). 西华大学外文资料翻译 5 When the power house is located near the dam, as is generally done in the low head installations。 it is known as concentrated fall hydroelectric development. But when the water is carried to the power house at a considerable distance from the dam through a canal, tunnel, or penstock。 it is known as a divided fall development. (3) Pumped storage plants. A pumped storage plant generates power during peak hours, but during the offpeak hours, water is pumped back from the tail water pool to the headwater pool for future use. The pumps are run by some secondary power from some other plant in the system. The plant is thus primarily meant for assisting an existing thermal plant or some other hydel plant. During peak hours, the water flows from the reservoir to the turbine and electricity is generated. During offpeak hours, the excess power is available from some other plant, and is utilized for pumping water from the tail pool to the head pool, this minor plant thus supplements the power of a。