Predictive Control of Three Phase AC/DC Converters

4 Sector 5Sector Sector 2
7 Sector 8Sector Sector 5
3.3. SWITCHING TABLE BASED DIRECT POWER CONTROL 23
States Sector(γ ΨL )/Voltage Vector U P (n)
d P d Q 1 2 3 4 5 6 7 8 9 10 11 12
0 0 5 6 6 1 1 2 2 3 3 4 4 5
0 1 6 1 1 2 2 3 3 4 4 5 5 6
1 0 0 5 7 6 0 1 7 2 0 3 7 4
1 1 0 0 7 7 0 0 7 7 0 0 7 7
Table 3.2: Switching table related to virtual flux vector position γ ΨL
(a)
β
(010)
UP3
Sector 3
(b)
β
(110)
UP2
(010)
UP3
Sector 6
(110)
UP2
α
α
(011)
UP4
(100)
UP4 UP1
(011)
(100)
UP1
(001)
6 Sector 7
UP5
(101)
1 Sector 12
UP6
Sector 8Sector 9 Sector 10Sector 11
(001)
9 Sector 10
UP5
Sector 11Sector 12Sector 1Sector 2
(101)
4 Sector 3
UP6
Figure 3.9: Sector selection for: (a) ST-DPC, (b) VF-ST-DPC
Instantaneous active and reactive power can be calculated from measured line
currents i Labc and:
• measured line voltages (3.13), (3.14),
• estimated line voltages (3.17), (3.18),
• estimated virtual flux (3.20), (3.21).
Basic active P and reactive Q power equations are given as:
P = 3 2 R(U LI ∗ L) = 3 2 (U LαI Lα + U Lβ I Lβ ) (3.13)
Q = 3 2 I(U LI ∗ L) = 3 2 (U LβI Lα − U Lα I Lβ ) (3.14)
Taking into consideration VSC mathematical model (2.13), (2.14) line voltage
U L can be calculated as:
where U P is given as:
U Lαβ = L dI Lαβ
dt
+ RI Lαβ + U P αβ (3.15)
U P αβ = U DC S αβ (3.16)