远距离电能输送采用高压输送的原因

Page2.The reasons of long-distance power transmission adopts high voltage transmission(远距离电能输送采用高压输送的原因)

1.English text

Long-distance transmission power why want to adopt high transportation can be from the following several aspects that:

Firstly,the electric power plants emit, need is used electric power transmission lines conveying out, because of transmission lines are resistance, and the transmission is longer, the more resistance. When an electric current passes through the transmission will produce hot, part of electric energy into internal energy and lost.

By including joule law: Q = I2Rt knowledge, in transmission time certain circumstances, current heat generation and transmission of the current is proportional to the square, and transmission line resistance become direct ratio. Want to reduce power loss, one is to reduce the transmission line resistance, 2 it is to reduce the current transmission intensity. In transmission line resistance cannot change circumstances, take to reduce the flow of electric current method, it can obviously reduce electricity losses, if the current reduced to the original 1/2, loss of power is reduced to the original 1/4.

According to P = UI, we can conclude that when power, voltage must rise, can reduce the current strength. Therefore, the actual conveying electricity is to adopt the method of hv transmission to reduce the current strength transmission, thus reduce transmission process electricity consumption. Therefore, high voltage grade lines to transmit power low voltage level line loss is small, the transmission distance long.

In conveying certain power and transportation distance certain premise, the higher the voltage, current and smaller. This can bring as follows: (1) the benefits of the current line flows is small, can reduce line cross-sectional area, save nonferrous metals; (2) line of small current flows in a circuit, can reduce power loss and voltage

loss.

Secondly,electricity transmission, whether ac power or HVDC transmission, the general trend is increasingly high voltage level, its main reason is:

1.Lines corridor consideration. In a country with plenty more narrow country, land price high or by topography constraints, the factors will show delirious. Economical comparison shows: each raise a voltage grade, the utilization rate of electric power transmission corridor can improve 2 to 3 times. In addition to the stability of the consideration, the same voltage grade multiple transmission line total transmission ability is not the sum of every circuit transmission capacity, but transmission voltage level enhancement, transmission capacity will greatly improve.

2.Short-circuit current consideration. Transmission systems allow the shortcircuit current cap is by the system structure and breaker open circuit ability of the decision. By higher voltage shouldering the main transmission task, low voltage system short circuit current are not increase, and can satisfy the existing breaker open circuit ability.

3.And system operation reliability and economical efficiency consideration. Ultrahigh pressure and uhv transmission, give power equipment, especially the transformer, transformer, circuit breakers, lightning arrester and other manufacturing development, operation management brings a new task and goal.

Power transmission areas, "high pressure" concept is constantly changing. In view of the actual research and operation needs, now usually divided into: 35kV voltage level below level, called distribution voltage, 110kV ~ 220kV voltage grade, called high-pressure, 330kV ~ 500kV voltage grade, called ehv, 1000kV class above voltage grade, called uhv.

Key words:Long-distance power lost，High-voltage transmission

2.中文翻译及分析

远距离输送电能为什么要采用高压输送可从以下几个方面说明：

一、电厂发出的电，需要用输电线路将电能输送出去，由于输电线路是有电阻的，