从控制结构上来划分，电控系统可以分为哪四个部分？
参考答案：
（1）电网级控制部分：主要包括总的有功和无功控制，远程监控等。
（2）整机控制部分：主要包括最大功率跟踪控制，速度控制，自动偏航控制等。
（3）变流器部分：主要包括双馈发电机的并网控制，有功无功解耦控制，亚同步和超同步运行控制等。
（4）变桨控制部分：又分为统一变桨控制和独立变桨控制两种，大型风电机组大多采用了独立变桨方式。
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| I have a very useful dictionary. It has a lot of words. It gives many meanings for 1 word. But I always read the first meaning of a word in the dictionary. I never read the other meanings, because I wanted to read my book 2 This morning, 3 I was reading a book, I met a strange sentence. It looked 4 first. The sentence had six words:" Draw a picture of your house" I know five words in this sentence, but I didn't understand one word. I 5 "draw". I opened my dictionary and 6 the first meaning of "draw". It was " pull". I said to myself " Now I know all the words, and I think I can understand the sentence."SO I wrote the meaning of the sentence" Pull a picture of your house."I read it, and" What is the meaning of it.'? I don't understand it." My friend Dick read my new sentence. He laughed. He picked 7 my dictionary, and said to me. "Look, Jack. The second meaning of' draw' is' make a picture 8 a pen, a pencil 9 brush'. So the sentence means: Make a picture of your house." I understood! I thought Dick was wonderful. And 10 I knew how to use my dictionary. | ||||
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