DAMPER WINDING PHENOMENA OF SYNCHRONOUS GENERATOR UNDER UNBALANCED STEADY-STATE CONDITION: A CASE OF 500 KV EHV JAMALI SYSTEM

  

DAMPER WINDING PHENOMENA OF SYNCHRONOUS GENERATOR

UNDER UNBALANCED STEADY-STATE CONDITION:

A CASE OF 500 KV EHV JAMALI SYSTEM

  1) 2) 2) 2) Sugiarto , Sasongko Pramono Hadi , Tumiran , F. Danang Wijaya 1) Electrical Engineering Department, Sekolah Tinggi Teknologi Nasional, Yogyakarta, Indonesia. 2) Electrical Engineering Department, Gadjah Mada University, Yogyakarta, Indonesia. danang@te.ugm.ac.id

  

ABSTRACT

The performance of three different damper winding configurations of a synchronous generator under unbalanced

steady-state condition of the power system to which it is connected are investigated in this paper. This synchronous generator

is a source of electrical energy generation system in the 500 kV EHV Jawa-Madura-Bali (or Jamali) System with

untransposed transmission lines and many single-phase loads.

  Induced currents of damper windings under the unbalanced steady-state system conditions, when the synchronous

generator is equipped with and without damper winding, are measured and analyzed. Active windows with this model are

developed using Matlab’s Graphical User Interface (GUI) capability to examine the dynamic behavior of the machine after

small perturbations, focusing on electromagnetically dynamic as affected by load unbalance. EDSA 2000 software is used to

derive the generator’s terminal inputs through load-flow analysis on the grid.

  Keywords: Damper winding, Unbalanced steady-state condition, The 500 kV EHV Jamali, GUI, EDSA 2000

INTRODUCTION oscillations are investigated analytically in this

  paper. The differences in performance between the Many researcher have studied the performance machine with and without damper windings are of damper windings since their introduction to discussed in terms of its induced currents of damper synchronous generator (Doherty and Nicle, 1926; windings and generator terminal values such as Boldea, 2006). However, the characteristics of electrical power output. The simulation was damper windings and their effects on the dynamics conducted on a one-generator connected to the 500 of generator in the electric power system have yet kV EHV Jamali System. to be sufficiently clarified (Matsuki et al, 1994). Moreover, study considering the experimental

STUDY SYSTEM

  aspect of damper windings effect have been quite

rare. The direct measurement of damper winding The studied power system is the 500 kV EHV

currents is quite difficult since the damper windings Jamali System that comprises 4-regions, such as

rotate with the rotor. Then, it has been generally Banten-Jakarta (Region 1) , West Java (Region 2),

difficult to realize the state of including damper in Central Java-Yogyakarta (Region 3) and East Java-

the practical generator to check the effects of the Bali (Region 4). It also has 71 line nodes, 27 lines

damper windings experimentally. Therefore, only of inter buses and 9 generator nodes, as shown in

simulation studies have been conducted to Fig. 1

  . In this system, Paiton’s bus is the swing

investigate them by including the generator node and others are the PV nodes. System capacity

parameters related to the damper windings in the is 100,000 MVA. The Test generators are Tanjung

analysis. But the simulation has a consequent it Jati B. follows that the accuracy of results obtained by analytical techniques has been difficult to be

  Test generator _{G_TJ.T-B G6_GRESK} G G checked, leaving a lot of uncertainties about the _{G4_SGLN G1_SRLYA TJATI_B GRESK SBYBART G2_SRLYA} G characteristics of damper windings. _{BEKASI SAGULING}

  G G A 820 MVA round-rotor synchronous _{SURALAYA IBT_BKS1 IBT_BKS2 CAWANG BDGSLTAN IBT_GRSK IBT_SBT1 IBT_SBT2} generator model has been specially designed for _{G5_CRATA} ^G8_GRATI

  G _{IBT_SLY1 IBT_SLY2} G ^IBT_BDG2 investigating the characteristics of damper _{CILEGON IBT_CWG1 GRATI IBT_CWG2} ^IBT_BDG1 _{CIRATA UNGARN} windings. A new method of measuring both _{IBT_CLG1 IBT_CLG2 IBT_CRT1 IBT_UGN2 G G7_PAITN IBT_GRTI} induced currents and voltages in the damper bars _{GANDUL CIBNONG} ^IBT_CRT2 _{MDRNCANG PAITON IBT_UGN1} has been developed. The damper bars are specially _{IBT_GDL1 IBT_GDL2 G3_MTWAR} designed to be easily interconnected or _{KEMBNG AN IBT_CBG1 IBT_CBG2 CIBATU TASIK} ^IBT_MDRC _{IBT_PTN1 IBT_PTN2 DEPOK PEDAN KEDIRI} G disconnected to simulate the state of including or _{IBT_KBG1 M.TAWAR} that of excluding damper effect. The performances ^{IBT_KBG2 IBT_DPOK IBT_CBT1} _{IBT_CBT2} ^{IBT_CBT3 IBT_TSIK} _{IBT_PDN1 IBT_PDN2 IBT_KDRI} of the damper windings under the power system Fig. 1. The studied power system which is connected to the 500 kV EHV Jamali System through a 18 kV parallel transmission line. The synchronous generator used in this study is a 820 MVA. 4-pole, 50 Hz, round-rotor generator, abc to dq0 Converter

Generator Block

  

Fig. 2. Balanced generator with unbalanced inputs

Gain

• – +

Gain Slip

  X X

Mux

Gain

  X X

Mux

• Mechanical loop Electrical loop

  

Fig. 3. The inside section of synchronous generator

q-axis

  ω b kq

• + I

  The model of this generator is shown in Fig. 3. b θ r

  V i kq b The generator has single damper per each axis g

  I a

  V a i g - - + winding, such d-axis and q-axis. Damper windings v

• + g

  f a in the equivalent generator model can be used to a-axis a-axis

• - +

  v f represent physical armotisseur windings (Fig. 4).

• - V

  i c f

  I c kd

  d d-axis c

• + i

  Rotor Stator Fig. 4. Generator winding with armotiseur The mathematical description or model develop is based on concept of an ideal synchronous generator. The fields produced by the winding currents are assumed to be sinusoidal distributed around the air-gap. This assumption of sinusoidal field distribution ignores the space harmonics, which may have secondary effects on the machine’s behavior. It is also assumed that stator slots cause no appreciable variation of any of the rotor winding inductances with rotor angle.

  To investigate the effect of damper windings on generators under unbalanced steady state operation, a “hybrid” method by combination between unbalanced three phase load flow analysis and rotor’s qd0 reference frame of synchronous generator model which substitutes the model of

  Fig. 6. The main window of the software tool generator in load flow analysis can be used. A software package which applied Matlab’s GUI facilities has been created for analysis damper under unbalanced steady-state conditions (Fig. 5). As an example of using Matlab’s GUI capabilities, menu and plotting commands are implemented in a script file to provide interactive windows. The main menu, which is displayed after running the file, are shown in Fig. 6 and Fig. 7.

  The verification of the generator model is judged through comparing between generator’s respon by PSS Tecquipment NE9070 (Fig. 10) and by the proposed simulator under no load, balanced and unbalanced conditions, respectively.

  Fig. 7. The window of inserting the inputs

User Request Simulation Command

  for balanced generator and unbalanced inputs GUI Matlab Simulink

  The verification of the generator model is judged through comparing between generator’s

Result Plot Result Data

  respon by PSS Tecquipment NE9070 (Fig. 8) and by the proposed simulator under no load, balanced and unbalanced conditions, respectively (Sugiarto Fig. 5. Designed Simulator with GUI et al , 2013).

  ia [ p u ]

  2

  4

  5

  6

  7

  8

  9

  10

  0.5

  1

  1.5

  2.5 Time [second]

• 1
• 0.5
>2
• 1.5

  2

  Current in Phase a

  1

  2

  3

  4

  5

  6

  7

  8

  3

  1

  10

Conditions of Synchronous Generator Phase Tanjung Jati B Voltage [p.u]

  4 Time [second]

  Fig. 8 . PSS Tecquipment NE9070

  Using EDSA 2000 software program one can get the flow calculation results from Fig. 1. Table 1 presents inter-phase voltage values of the test generator terminal, before and after loading condition. It is shown that under unbalanced loads condition, the phase angles of terminal generator voltage are deviated from its balanced value. The biggest deviation occurs when the grid operates under balanced load condition.

  Table 1. Values of generator terminal voltage

  Connected the grid and load balance a b c

  Connected the grid and load imbalance of 5% a b c

  Fig. 14. Currents in phase-a of Tanjung-Jati- B of balanced loads and no-damper winding

  ( a ) ( b ) Fig. 15. Currents of Tanjung-Jati-B at balanced loads and d-axis damper winding: a. in phase-a b. in d-axis damper winding

DEMONSTRATION

  Current in Phase a

  3

  0.4

  2

  1

  Current in horizontal-axis damper winding

  ik d [ p u ]

  1.8 Time [second]

  1.6

  1.4

  1.2

  1

  0.8

  0.6

  9

Current in Phase a

• 4
• 3
• 2
• 1

  ia [ p u ]

  6

  ( a )

  1

  ia [ p u ]

  2

  3

  4

  5

  10

  9

  8

  7

  5

  2

  4

  3

  2

  1

  6

  7

  8

  9

  10

  0.5

  1

  1.5

• 1
• 0.5
>2
• 1.5
• 0.6
• 0.4
• 0.2

  Current in Phase a

  0.5

  1

  1.5

  2

  2.5 Time [second]

  ia [ p u ]

  Current in Phase a

• 0.5
>1.5 <>2.5 <
• 1
• 0.5

  0.5

  1

  1.5

  2

  2.5 Time [second]

• 2
0.5>1.5 <>2.5
• 2

  6

  0.2

  1.4

  1.5

  1.6 Time [second]

  ik d [ p u ]

  Current in vertical-axis damper winding

  ik q [ p u ]

  0.8 Time [second]

  0.6

  0.4

  10

  1.2

  9

  8

  7

  6

  5

  4

  3

  2

  1

  1.3

  1.1

  5

  0.9

  4

  3

  2

  1

  7

  ia [ p u ]

  8

  9

  10

  1

  1

  10

  9

  Current in horizontal-axis damper winding

  7

  6

  5

  4

  3

  2

  8

  2 Time [second]

  ik d [ p u ]

  7

  2

  1

  Current in vertical-axis damper winding

  ik q [ p u ]

  1 Time [second]

  0.8

  0.6

  0.4

  0.2

  10

  9

  8

  6

  4

  5

  4

  3

  2

  1

  a. in phase-a b. in d-axis damper winding

  ( a ) ( b ) Fig. 19. Currents of Tanjung-Jati-B at 5% of un- balanced loads and d-axis damper winding:

  c. in q-axis damper winding Fig. 18. Currents in phase-a of Tanjung-Jati- B of %5 of unbalanced loads and no damper winding

  b. in d-axis damper winding

  ( c ) Fig. 17. Currents of Tanjung-Jati-B at balanced loads and d-axis and q-axis damper windings: a. in phase-a

  ( a ) ( b )

  ( b ) Fig. 16. Currents of Tanjung-Jati-B at balanced loads and q-axis damper winding: a. in phase-a b. in q-axis damper winding

  3

  5

  1.8

  5

  1.6

  1.4

  1.2

  1

  0.8

  0.6

  0.4

  10

  9

  8

  7

  6

  4

  6

  3

  2

  1

  Current in Phase a

  ia [ p u ]

  2 Time [second]

  1.5

  1

  0.5

  10

  9

  8

  7

  Current in horizontal-axis damper winding

• 0.6
• 0.4
• 0.2

  Current in Phase a

  ( b )

  3 Current in vertical-axis damper winding

  0.34

  2 0.335

  1

  0.33

  ] u p [ ia

  ] u p

  0.325

  [ q

• 1

  ik

  0.32

• 2

  0.315

• 3

  1

  2

  3

  4

  5

  6

  7

  8

  9

  10 Time [second]

  0.31

  1

  2

  3

  4

  5

  6

  7

  8

  9

  10 Time [second]

  ( a )

  Current in vertical-axis damper winding

  0.7

  ( c ) Fig. 21. Currents of Tanjung-Jati-B at balanced

  0.65

  loads

  0.6

  and d-axis and q-axis damper windings:

  0.55

  a. in phase-a ]

  0.5

  u p b. in d-axis damper winding

  [ q c. in q-axis damper winding

  0.4

  0.35 Figure 14 to Figure 21 represent all of currents

  0.3

  of Tanjung Jati- B’s generator under balanced and

  0.25

  1

  2

  3

  4

  5

  6

  7

  8

  9 10 unbalanced load conditions. There is an interesting Time [second]

  phenomenon which has been occured. The ( b ) waveform of current in phase-a of synchronous Fig. 20. Currents of Tanjung-Jati-B at 5% of un- generator with tends to be sinusoidal form balanced loads and q-axis damper winding: eventhough under 5% of unbalanced load by using

  a. in phase-a b. in q-axis damper the d-axis and q-axis damper windings, shown in winding Fig. 21.b . Meanwhile, the current in phase-a when generator applied the d-axis damper winding

  Current in Phase a is much better compare to generator applied the q-

  1.5

  axis damper winding. Moreover, the synchronous generator which do not apply the damper winding,

  1

  wheter d-axis damper winding or q-axis damper

  0.5

  winding, has a bad current in- phase’s output.

  ] u p [ ia

CONCLUSION

• 0.5

  A useful simulator for analysis “Damper

• 1

Winding Phenomena of Synchronous Generator Under Unbalanced Steady-State Condition: A Case

• 1.5

  1

  2

  3

  4

  5

  6

  7

  8

  9

  10

  Time [second]

  of 500 KV EHV Jamali System ” has been presented

  in this paper. Two operation conditions of the ( a ) synchronous generator, load balanced and load

  Current in horizontal-axis damper winding

  1.4

  imbalance of 5% are mathematically modeled then

  1.395 simulated using Matlab.

  1.39 The simulation results state that the using of 1.385

  damper windings at both d-axis and q-axis has significant effect on the outputs of generator ]

  1.38

  u p [ d dynamic during unbalanced steady state condition. ik 1.375

  Surprisingly, the using of d-axis damper winding

  1.37

  exhibit the better output of generator currents in

  1.365 phases that by using of the q-axis damper winding.

  1.36 The developed tool is made easy to use by 1.355

  1

  2

  3

  4

  5

  6

  7

  8

  9

  10

  providing an active link with the simulated models

  Time [second]

  using some of Matlab’s GUI functions. The given examples demonstrate helpfulness of the developed tool for analyzing damper winding phenomenon of synchronous generator connected to the grid and under unbalanced steady-state operation

REFERENCES

  Boldea, I., 2006, Synchronous Generator, Boca Raton,FL: Taylor &amp; Francis Group, LLC, 2006 Doherty, R.E. , Nickle, C.A., 1926, Synchronous Machines I - An Extension of Blondel's Two- Reaction Theory, Transactions A.I.E.E., vol. 45, pp. 912-926, June. Matsuki, J., Katagi, T, Okada, T., 1994,Damper Windings Phenomena of Synchronous

  Machines During System Oscillations, IEEE Transaction on Energy Conversion , Vol. 9, No. 2, June.

  Teaching the Large Synchronous Generator Dynamic Model under Unbalanced Steady-

State Operation, Poceedings of 2013

  International Conference on Information Technology and Electrical Engineering, (ICITEE 2013) , 7-8 October, Yogyakarta, Indonesia.