Exam text content

Tampere University 18.9.2019
DEE-34026 Power Electronic Applications for Power Ouality

Pertti Pakonen Programmable calculator allowed 4 guestions/ ä 6 p

1. Dimensioning of a STATCOM

A three-phase four wire unbalanced star-connected load (Za = 2.0 + j0.5 pu, Z»= 3.0 + j1.0 pu and
Ze=4.0 + jI.5 pu) has an input line-to-line voltage of 690 V, 50 Hz, AC supply. Base impedance is
1.75 O per phase. The load should be compensated to draw only balanced active power from the
AC supply using STATCOM described in the figure below.

The supply can be assumed stiff enough that the load has no effect on the voltage level.
Additionally, neutral current compensation of the STATCOM can be ignored.

Calculate when the STATCOM is operating

a) load and supply phase currents and load neutral current
b) STATCOM phase currents

c) KVA rating of the STATCOM

 

 

 

 

(0) —
TF FT — i
sa fa ta
10
vo EN — (o
0)

7

V, = 690 V, 50 Hz "a

AC supply

 

 

 

 

 

Fig. 1. Three-Phase STATCOM for compensation of unbalanced star connected load.

2. Active power filter (APF)

a) Why shunt-connected APF is connected close to the industrial load?

b) What measurements are reguired to control the shunt-connected APF?

c) What is the operation principle of shunt-connected APF?

d) What are the advantages and disadvantages of APFs compared to passive filters?
e) What means hybrid active power filter?

f) What means UPOC? Why UPOC is connected to the power system?

12)
Tampere University 18.9.2019
DEE-34026 Power Electronic Applications for Power Ouality

Pertti Pakonen Programmable calculator allowed 4 guestions/ & 6 p

3. SVC

a) Why SVC is connected to the system shown in Fig. 2?

b) Explain the structure of SVC. What components SVC includes?

c) Explain shortly the operation of an SVC.

d) Why the passive compensation circuit is added as a part of SVC installation?

e) Would it be possible to use passive compensation instead of SVC in the case show in
Fig. 2? Explain why.

D Why better results are obtained by using STATCOM instead of SVC in Fig. 2?

 

 

 

non compensated
with STATCOM
— with SVC

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hy huisa A

20 40

 

id

 

 

Main
Transformers

EAP
30
Transformers

 

        
   
   
    
 
 
 
 
    

SKYMISY
JOMYÄ
KA

Flicker Sensalion

Source Bus
400 kV
50 Hz
9100 MVA a
FAP Bus
KY

   

 

 

 

Svc

 

time(s)
Fig 2. SVC with electric arc furnace (EAF) in Mobarakeh steel company
(https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7827763)

 

4. STATCOM

a) Why STATCOM is connected to PCC of the wind park as shown in Fig. 3?

b) Explain shortly the operation principle of STATCOM.

c) What is a modular multileve! converter (MMC) and why are they used e.g. in high
power STATCOMs? What disadvantages do MMCs have?

d) What are the advantages and disadvantages of STATCOM compared to SVC?

e) What means STATCOM with energy storage (ESTATCOM)?

 

  
 
 
  

 

  
   
 
     

 

 

 

 

 

 

 

  

X
RI wind
KUN transformer gearbox rotor
: GSC — RSC 1.
N T=
U IT >=
LAN erowbar
STATCOM system DFIG system

Fig 3. STATCOM with wind park
(https://ieeexplore.ieee.org/stamp/stamp.jsp?ip=&arnumber=8216443)

202)