问题 问答题 简答题

为什么《电力法则》要规定每座发电厂内最大的单机容量不得超过电网系统总容量的8%~10%?

答案

参考答案:

随着电力系统的不断扩大,单机允许容量也相应提高,但单机容量要与电网系统容量相匹配。这样才能保证整个电网系统的安全稳定。如果有一台超过系统总容量8%~10%的发电机组突然退出电网系统,就会大大影响整个系统的安全和稳定,系统负荷曲线突然变化,从而造成整个系统的电压、频率以及负荷产生不稳定的波动,对整个电网系统的安全稳定供电带来了一定威胁和困难,所以,单机容量的设计值,主要是根据电网系统的安全稳定和总容量来决定的。

阅读理解

阅读理解。

      People have strange ideas about food. In the 18th century, Americans never ate tomatoes. They grew them

in their gardens because tomato plants are so pretty. But they thought the vegetable was poisonous. They called

tomatoes "poison apples." 

      President (总统) Thomas Jefferson, however, knew that tomatoes were good to eat. He was a learned man.

He had been to Paris, where he learned to love the taste of tomatoes. He grew many kinds of tomatoes in his

garden. The President taught his cook a way, for a cream of tomato soup (汤). This beautiful pink soup was

served at the President's next dinner party. The guests (客人) thought the soup tasted really good. They never

thought their President would sever his dinner guests poison apples. Jefferson never spoke to his honored guests

about the fact.

1. Which of the following is true? [ ]

A. Americans never ate tomatoes after the 17th century.

B. Even now Americans don't eat tomatoes.

C. It was not until after the 18th century that Americans began to grow tomatoes for food.

D. Americans didn't eat tomatoes before the 19th century.

2. Jefferson was a president of _______. [ ]

A. a European country

B. the United States

C. England

D. France

3. Jefferson learned that tomatoes were good to eat _______. [ ]

A. even when he was a little boy

B. because his parents told him so

C. from books

D. while he was in Paris

4. From the passage we know all the honored guests invited by Jefferson were _______.[ ]

A. people of his own country

B. people from other countries

C. Frenchmen

D. men only

5. According to the passage, which of the following is wrong? [ ]

A. All the guests thought the cream of tomato soup was nice.

B. All the guests thought the soup had a good taste.

C. All the guests thought the taste of the beautiful pink soup was nice.

D. None of the guests ever thought if the soup was poisonous or not.

单项选择题