Voltage H Repetitive Control with a Frequency-adaptive Mechanism - Control of Power Inverters in Renewable Energy and Smart Grid Integration - page 118

15
30

0

−15

−30

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

Time [s]

(a) Local load voltages

5 5

i A i B i C THD of u A =1.32%

4

2.5

3

0

2

−2.5

1

−5 0

5 10

i a i b i c THD of i a =6.92%

2.5

0 5

−2.5

−5 0

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0 5 10 15 20 25 30

Time [s] Harmonics order

(b) Inverter output currents and grid currents (c) Spectra of voltage u A and grid current i a

Figure 5.10 Grid-connected mode: with an unbalanced local load

30 4

u ref u A i ref i a

15 2

0 0

−15 −2

−30 −4

4 2

e u e i

2 1

0 0

−2 −1

−4 −2

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

Time [s] Time [s]

(a) u A , its reference u ref and the error e u (b) i a , its reference i ref and the error e i

5

THD of u A =1.16%

4

3

2

1

0

10

THD of i a =6.67%

5

0

0 5 10 15 20 25 30

Harmonics order

(c) Spectra of local load voltage u A and grid current i a

Figure 5.11 Grid-connected mode: without a local load