Flexible distribution systems through the application of multi back-to-back converters

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Chapter 4

b

Q

c

Q Q

d

Intelligent Node

Q

a

(a) Limited mitigation in mixed resistive/inductive network.

b

Q

c

Q Q

d

Intelligent Node

Q

a

(b) Improved mitigation with series reactors.

Figure 4.12: Voltage dip mitigation in cable network, IN without storage.

10.5 kV ≈ 55 A) of the IN. The reactors’ rating is 6 MVA with Uk = 4%. The calculation results are given in Table 4.2, where VM BB is the main busbar voltage, VT Rn is the voltage on the secondary side of reactor Ln and VIN n is the voltage on port n of the IN. Table 4.2: Simulation results voltage dip mitigation example network. Base Case ISC VM BB VT R1 VT R2 VT R3 VIN 1 VIN 2 VIN 3 VIN 4

(kA) (p.u.) (p.u.) (p.u.) (p.u.) (p.u.) (p.u.) (p.u.) (p.u.)

4.68 0.854 0.838 0.850 0.827 0.829

Base Case and Q 4.74 0.864 0.863 0.867 0.859 0.859

Reactors

Reactors and Q

3.29 0.845 0.845 0.600 0.841 0.825 0.841 0.815 0.816

3.33 0.855 0.862 0.608 0.870 0.870 0.864 0.865 0.865

From the calculation results it can be seen that the short-circuit current is limited significantly by the application of the reactors. In the situation with reactors the short-circuit has a large reactive component,


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