simulation of electromagnetic transients in...

1 | Simulation of Electromagnetic Transients in MCSR

Simulation of Electromagnetic Transients In Magnetically Controlled Shunt Reactors Manufactured

at PJSC «Zaporozhtransformator» during FAT and under Operation

Leonid Kontorovych, Technical Director of ZTR PJSC, PH.D. in Engineering Sciences; Igor Shyrokov, head of the department of reactors control systems development

Nowadays magnetically controlled shunt reactors (MCSR) are widely used at high-voltage networks for control of electric power fluxes during normal and emergency operating modes of the power system.

Reactor operating modes during FAT and under operation are significantly different. Such difference is caused by the fact that there are no powerful sources of high voltage of different value at the manufacturing factory and as a result reactor resonance power-supply circuit is used during FAT. In addition to that during FAT at the manufacturing factory there is no equipment equivalent to grid and substation equipment.

Mathematical models of MCSR, testing equipment, grid and substation equipment are developed at PJSC «Zaporozhtransformator» for evaluation of MCSR operation in different modes during FAT and under operation. Development of adequate models allows to try-out and optimize MCSR automatic control system algorithms and also to check new electromagnetic part and MCSR semiconductor converter designs. Development of models is performed on the MATLAB/Simulink/SimPowerSystem software package [1, 2].

Descriptions of MCSR electromagnetic part models of different design, testing equipment models, models for simulation of different FAT of electromagnetic parts are described in the article. There are also indicated experimental data and MCSR operation calculation results during FAT and under operation.

Single line diagram of RODU-60000/500 electromagnetic part of three-phase reactor RTU-180000/500 (design A) is indicated in fig. 1.

Electromagnetic part of such reactor consists of control winding (CrtW) with four sections, located in pairs around two semilimbs of magnetic system (CtrW11 and CtrW12, CtrW21 and CtrW22), and power winding (PW), around both semilimbs. The peculiarity of such design is that there is no compensation winding (CW). Bushings «a» and «x» are used for suppression of reactor current harmonic component and feeding of semiconductor converter, and bushings «+» and «-» of reactor control winding are used for control. Shunt resistor R, connected to control winding bushings, is used for forming of winding induction discharge circuit and for decrease of overvoltage value at winding bushings.


Fig.1. Single line diagram of RODU-60000/500 (design A)

In Fig. 2 it is shown single line diagram of electromagnetic part RODU-60000/500 of three-phase reactor RTU-180000/500 (design B).

Electromagnetic part of such reactor consists of compensation winding (CW) and control winding (CtrW) with two sections, located around two semilimbs of magnetic system, and also power winding (PW) around both semilimbs.

Fig.2. Single line diagram of RODU-60000/500 (design B)

MCSR electromagnetic part models have been developed in two ways. The first way – modeling on the basis of reactor magnetic system equivalent circuit (EM model circuit).


Connection between electric and magnetic circuits in the models based on reactor magnetic system equivalent circuit is performed with the help of the magnetic flux source. Such connection is shown in fig. 3. Nonlinear elements of magnetic circuit were realized with the help of magnetic voltage sources, examples of which are shown in fig. 4.

Fig.3. Connection between electric and magnetic circuits

Fig.4. Realization of the nonlinear element of magnetic circuit

Equivalent circuit of magnetic system of reactor RODU-60000/500 (design A) is shown in fig.5, reactor electromagnetic part EM model circuit Эквивалентная схема замещения магнитной системы реактора РОДУ-60000/ is shown in fig. 6, and the results of EM model modeling during supply of AC voltage to PW and DC voltage to CtrW are shown in fig.7.

Fig.5. Reactor magnetic system equivalent circuit (design A)


2

B2

1

B1

6

x

5

a

4

X

3

A

2

-

1

+

in_E

out_E

in_M

out_M

winding_PW11

in_E

out_E

in_M

out_M

winding_CW22

in_E

out_E

in_M

out_M

winding_CW21

in_E

out_E

in_M

out_M

winding_CW12

in_E

out_E

in_M

out_M

winding_CW11

Rmo_3

Rmo_2Rmo_1

B

in_R

mm

out_

Rm

m

Rmm_2

B

in_R

mm

out_

Rm

m

Rmm_1

Fig.6. Reactor EMP EM model circuit (design A)

Fig.7. Modeling results of reactor EM model (design А)

а) current in CtrW; б) induction in semilimbs; в) current in PW; г) voltage in CW

The second way – modeling of MCSR electromagnetic parts on the basis of reactor equivalent


circuit (ET models). Such models were developed using SimPowerSystem-units of Saturable Transformer, based on T-shaped transformer equivalent circuit.

Reactor RODU-60000/500 electromagnetic part ET model circuit (design A) is indicated in fig.8, and results of ET model modeling during supply of AC voltage at PW and DC voltage at CtrW are shown in fig.9

6

x

5

a

4

X

3

A

2

-

1

+

1

2

3

T2

1

2

3

T1

Fig.8. Reactor EMP ET model circuit (design A)

Fig.9. Modeling results of reactor ET model (design A)

а) current in CtrW; б) induction in semilimbs; в) current in PW; г) voltage in CW

In contract to EM models ET model parameters are defined on the basis of calculation or measurement of winding and their part self-inductances and mutual inductances, estimated or measured losses in windings, magnetic core and structural elements. For recording of nonlinearity it is used the dependence B(H) for equivalent reactor magnetic circuit (on the basis of calculation or measurement).

It means that parameters of ET model depict the parameters of real reactor more precisely.


Further in the article there are examined the calculation results according to ET type models.

Functional circuit of the model for measurement of reactor (design A) losses at no-load is shown in fig.10. Circuit of the model for measurement of reactor losses at short-circuit is shown in fig. 11. Circuit of the test model for checking of reactor power is shown in fig. 13. Results of modeling and results received during FAT (reactor factory numbers 157982, 157983, 157984) are shown in tables 1-3.

Comparison of calculations and experimental data allows us to make a conclusion that developed model of reactor RODU-60000/500-N1 electromagnetic part (design A) is very precise.

B1

B2

+

-

a

x

A

X

em_part

signal rms

Uaxrms

U

Scope

R

1

Multimeter

signal rms

Iaxrms

i+-

Iax

Fig.10. Model for measurement of reactor (design A) losses at no-load

Table 1. Results of modeling and measurement of reactor no-load losses (А)

Description Uax, kV Iax, А

Model 31,8 3,90

RODU-60000/500 (157982) 31,8 3,72

RODU-60000/500 (157983) 31,8 3,65

RODU-60000/500 (157984) 31,8 3,60

B1

B2

+

-

a

x

A

X

em_part

signal rms

UAXrms

U

Scope

R

1

Multimeter

signal rms

IAXrms

i+

-

IAX

Fig.11. Model for measurement of reactor (design A) losses at short-circuit


Table 2. Results of modeling and measurement of reactor short-circuit losses (А)

Description UAX, kV IAX, А

Model 35,70 48,2

RODU-60000/500 (157982) 36,96 49,5

RODU-60000/500 (157983) 35,70 48,2

RODU-60000/500 (157984) 36,30 49,5

alpha

pulse_1

pulse_2

ACV+

ACV-

pulse_former

B1

B2

+

-

a

x

A

X

em_part

30

alpha

Vsync

g ak

VT2

g ak

VT1

VAX v+-

UAX

Scope

R

12

OM

signal rms

i+

-

IAX

signal rms

i+-

I+-

D4

D3

D2

D1

Fig.12. Reactor (design A) test model for checking of reactor power

Table 3. Results of reactor modeling and power checking (А).

Description UAX, kV IAX, А I±, А

Model (calculation) 302 200,1 1845,3

RODU-60000/500 (157982) 302 203,3 1713,0

RODU-60000/500 (157983) 304 201,6 1682,5

RODU-60000/500 (157984) 303 200,1 1665,2

Circuit of reactor RODU-60000/500 (design B) electromagnetic part ET model is shown in fig.13, and calculation results of ET model during supply of AC voltage at PW and DC voltage at CtrW are shown in fig.14.


Functional circuits of the models which simulate reactor (design B) FAT are similar to those, already described, for reactor (design A). Results of modeling and results received during FAT of RODU-60000/500-NC1 (design B) (factory number 160714) are shown in tables 4-8.

8

minus

7

0

6

1

5

plus

4

x

3

a

2

X

1

A

1

2

3

T2

1

2

3

T1

R2

R1

Fig.13. Functional circuit of reactor (design B) EMP ET model

Fig.14. Calculation results of reactor (design B) ET model

а) current in CtrW; б) inductions in semilimbs; в) current in PW; г) voltage in CW


Table 4. Results of modeling and measurement of reactor (design B) losses at no-load at rated voltage supplied to CW

Parameter UCW, kV ICW, А PCW, kW

RODU-60000/500 (160714) 10,705 6,1200 33,494

Model 10,705 6,1185 33,485

Table 5. Results of modeling and measurement of reactor (design B) losses at no-load at rated voltage supplied to PW

Parameter IPW NO-LOAD, А PPW NO-LOAD, kW QPW NO-LOAD, кVАр

RODU -60000/500 (160714) 0,2090 32,432 54,521

Model 0,2092 32,409 54,501

Table 6. Results of modeling and measurement of reactor (design B) PW-CW short-circuit voltage

Parameter UPW, kV IPW, А PPW, kW

RODU -60000/500 (160714) 15,087 17,874 2,966

Model 15,087 17,875 2,972

Table 7. Results of modeling and measurement of reactor (design B) PW-CtrW short-circuit voltage

Parameter UPW, kV IPW, А PPW, kW

RODU -60000/500 (160714) 33,279 52,150 37,700

Model 33,279 52,149 37,694

Table 8. Results of modeling and reactor (design B) rated values

Parameter QPW, МVAr IPW, А ICtrW, А

Rated value 60,00 198,0 745,0

Model 60,13 198,9 747,9


Comparison of calculations and experimental data allows us to make a conclusion that developed model of reactor RODU-60000/500-CN1 electromagnetic part (design B) is very precise.

Possibilities of the developed model of reactor electromagnetic part have been tested by simulation of different processes and reactor operating modes during FAT.

For example, model functional circuit of reactor bringing into rated mode with the help of designed and manufactured at PJSC «Zaporozhtransformator» testing equipment for MCSR testing (MCSR TE) is shown in fig.15.

During this test reactor feeding is performed according to resonance circuit, which consists of synchronous generator, step-up transformers and capacitor bank.

Production and control of excitation current in reactor control winding is performed with the help of MCSR TE semiconductor converter, which is controlled by MCSR automatic control system (ACS).

signal rms

signal rms

signal rms

10

alfa_MMB

10

alfa_IMB

Z

V380

s

-+

V

rms

Upwrms

v+-

v+-

A

X

plus

1

0

minus

a

x

RODU_IR

RC

1 2

OM2000_TS

1 2

OM16_TS

PULSESI

V

A

X

plus

minus

MMB

i+

-

Irc

i+

-

Ipw

i+-

Icw

PULSESI

V

A

X

plus

minus

IMB

Add

alpha_deg

AB

Block

pulses

alpha_deg

AB

Block

pulses

1kV

Fig.15. Model of reactor bringing into rated mode with the help of testing equipment for MCSR testing

MCSR TE semiconductor converter consists of: single-phase bridge controlled rectifier (IMB element in fig.15), single-phase bridge controlled reversible converter (MMB element in fig. 15) and elements of converter shunt circuit (they are not indicated in fig.15 as they are not used during such type of test).

As converter thyristor and diode models there are used SimPowerSystem-units Thyristor and Diode, which allow to set the following parameters: element resistance when open, element inductance when open, direct voltage drop of open element, resistance of snubber resistor, capacity of snubber capacitor.

Functional circuit of single-phase bridge controlled rectifier model is shown in fig.16, single-phase bridge controlled reversible converter – in fig.17.


Rectifier consists of two thyristors and two diodes, each of which is protected by snubber resistor and capacitor. Rectifier is used for production and control of reactor preliminary biasing current. Rectifier feeding is performed from 0,4 kV network through 16 kVA transformer (OM16_TS element in fig.15).

Reversible converter consists of four thyristors, each of which is protected by snubber resistor and capacitor. Converter is used for production and control of reactor excitation current mostly during main operating modes from 0 up to 2500 A. Converter feeding is performed from reactor compensation winding through 2000 kVA transformer (OM2000_TS element in fig.15).

As in the used thyristor models control inputs are functional, there are no simulation elements of control signal forming in rectifier and converter models.

2

V

1

I

4

minus

3

plus

2

X

1

A

gm

ak

VT2

gm

ak

VT1

VD2VD1

1

PULSES

Fig.16. Controlled rectifier model

2

V

1

I

4

minus

3

plus

2

X

1

A

gm

ak

VT4

gm

ak

VT3

gm

ak

VT2

gm

ak

VT1

1

PULSES

Fig.17. Controlled reversible converter model


Simulation results of reactor bringing into rated mode are shown in fig. 18.

At the first stage of such test it is performed reactor initial excitation (check out time from 0 up to 10 sec. in fig.18). After establishment of set initial excitation current of tested reactor it is performed step-by-step voltage rise in reactor PW and, simultaneously, reactor excitation current control (check out time from 10 up to 30 sec. in fig.18).

Test complexity is caused on the one hand by limited generator power, on the other hand by possibility of generator self-excitation in case the value of capacity current, absorbed by capacitor bank from generator, exceeds the values of inductive current absorbed by reactor. I.e. incorrect chose of parameters of equipment, used during test, or operating mode parameters during test can lead to emergency test-stop and tests have to be repeated.

Fig.18. Modeling results of reactor bringing into rated mode

а) voltage in PW; б) current in CtrW; в) current in PW; г) current of capacitor bank;

д) difference of currents between PW and capacitor bank

Modeling results of reactor bringing into rated mode, shown as an example, allowed us to reveal the incorrect chose of parameters of equipment, used during test, which leads to impossibility of test due to generator self-excitation (check out time after 25 sec. in fig.18). Correction of parameters of test equipment according to the modeling results allowed us to carry out tests without emergency stops.

Therefore the calculation results of reactor (different designs) electromagnetic part models, test equipment models and models simulating different types of reactor FAT agree with experimental data received during FAT.

With the help of developed MCSR equipment models there was created a model for examination of MCSR under operation. Model functional circuit is shown in fig.19, example of modeling results is shown in fig.20.

Model consists of:


1. MCSR equipment – three electromagnetic parts of three-phase reactor of single-phase arrangement (1, 2 and 3 in fig.19) and two semiconductor converters (4 and 5 in fig.19). Models of MCSR equipment are similar to the models described earlier in this article.

2. High-voltage circuit-breakers (6, 7, 8 and 9 in fig.19) for the modeling of which there are used SimPowerSystem-units Three-Phase Breaker.

3. Power lines (10, 11, and 12 in fig.19) for the modeling of which there are used SimPowerSystem-units Three-Phase PI Section Line.

A

B

C

77

33

A

B

C

a

b

c

9

A

B

C

a

b

c

8

A

B

C

a

b

c

7

A

B

C

a

b

c

6

alpha

A

B

C

+

-

5

alpha

A

B

C

+

-

4

(+)

(-)

a x

A X

3(+

)

(-)

a x

A X

2

A

B

C

A

B

C

15

m

A

B

C

14

A

B

C

13

ABC

ABC

12

ABC

ABC

11

ABC

ABC

10

(+)

(-)

a x

A X

1

Fig.19. Model for examination of MCSR under operation

4. Equivalent elements of power system – voltage source (13 in fig.19) and load source (14 in fig.19). SimPowerSystem-units Three-Phase Source and Three-Phase Dynamic Load are used as models of source and load.

5. Element which simulates line emergency operation (15 in fig.19). SimPowerSystem-unit Three-Phase Fault is used as a model of this element.


Fig.20. Modeling results of MCSR (phase A) operating modes

а) voltage in PW; б) voltage in CW; в) voltage in CtrW;

г) current in CtrW; д) current in PW; е) induction in semilimbs.

Development and calculation of detailed models for different operating modes (control, switching, emergency) will allow to optimize parameters and algorithms of MCSR equipment, which will lead to MCSR reliability improvement during operation.

References:

1. Chjornyh I.V. Modeling of electric devices on MATLAB, SimPowerSystems and Simulink. – М.: Press; St. Petersburg: Piter, 2008 – 288 p.

2. Simulink. Model_Based and System_Based Design. Using Simulink. The Math Works, Inc. USA, 2002.

© Copyright 2014 Zaporozhtransformator PJSC. The document, or parts thereof, should not be copied, adapted, redistributed, or otherwise used without the prior written permission of Zaporozhtransformator PJSC.

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