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WIND ENERGY SYSTEMS - Cd3wd

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Chapter 5—Electrical Network 5–13<br />

E c<br />

E ca ❍❨ ❆❑<br />

❍<br />

❍<br />

❍<br />

❆<br />

❍<br />

❍<br />

❆<br />

❍<br />

❍<br />

❆<br />

❍✟ ❆<br />

✟✟✟✟✟✟✟✟✯ ✲ E a<br />

✁<br />

✁<br />

✁<br />

✁<br />

✁☛<br />

E b<br />

E ab<br />

❄<br />

E bc<br />

Figure 7: Balanced three-phase voltages for circuit in Fig. 5.6.<br />

✲ I a<br />

a<br />

<br />

b ✟<br />

<br />

✲ I b<br />

❍ ✟<br />

✟<br />

❍❍❍ ✟<br />

✟ ❍<br />

✠<br />

✟<br />

❍❍ ❍<br />

✟<br />

❍<br />

✟<br />

♠<br />

♠✟<br />

❍<br />

✟✟<br />

❍ ✁ ✁✁<br />

❆✟ ✟✟ ❆<br />

E ❆<br />

b Z<br />

❍<br />

❍✟ ✟✟✟ ❍<br />

❍ ❍<br />

❍✁ ✁✁<br />

Z<br />

❍<br />

❍✟ ✟✟ ❆<br />

❆✟ ✟✟<br />

❆<br />

✛ I n<br />

n<br />

<br />

E a<br />

♠E c<br />

Z<br />

c<br />

<br />

✲ I c<br />

Figure 8: Balanced three-phase wye-connected source and load.<br />

I a = E a<br />

Z = |E a|<br />

|Z| / − θ = |I a|/ − θ A (23)<br />

The other two currents are given by<br />

I b = |I a |/ − θ − 120 o A<br />

I c = |I a |/ − θ − 240 o A (24)<br />

The sum of the three currents is the current I n flowing in the neutral connection, which can<br />

Wind Energy Systems by Dr. Gary L. Johnson November 21, 2001

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