Geomagnetic Disturbances: Impact on Power System Components

Transcription

1 Geomagnetic Disturbances: Impact on Power System Components Sakis Meliopoulos Georgia Power Distinguished Professor School of Electrical and Computer Engineering Georgia Institute of Technology tlanta, Georgia Page 1

2 GIC Physics DC like currents in soil up to 10/km Corona Mass Ejection MagnetoSphere Interaction Page 2

3 Characteristics of Magnetic and Electric Field Levels of magnetic field and rate of change of magnetic field makes the electric field appear as DC for the electric power system From Effects of Geomagnetic Disturbances on Electric Power Systems, EPRI Report EL-7333, ugust 1991, by. P. Sakis Meliopoulos et al. Page 3

4 Magnetic and Electric Field Exist lways and Increase Drastically During Storms Example earth surface voltage measurements near Toole, UT 1 Grid Spacing: ft Model (Biquadratic) Node Indexing Discretization N N ' 0 W ' Y X Indicates max voltages of about 2 /mi K-index not reported B C P1 1Y 219' CR P0 SGM Location B C D P2 2Y P6 3B D Step oltage (m) (18:27) 100 (18:45) -100 (19:04) 0 (19:22) Probe Number E Scale (feet) 0' 45' 90' 135' 1 2 P3 3 3Y 4 P4 1B P5 2B Step oltage Measurement Setup ugust 11, 2004 Tooele Location dvanced Grounding Concepts / WinSGM E Page 4

5 Impact on Power System Components Main Issues of Concern: DC injection into Saturable Core Power pparatus Results into Current Distortion, Harmonics and Consequences ulnerable Power Equipment Saturable Core Power pparatus Generators: typically grounded via high impedance secondary concerns Solidly grounded transformers (two/three/four winding, autotransformers) Solidly grounded saturable core reactors Page 5

6 pplicable Circuit for GIC DC Only Magnetic Saturation Characteristics DC Equivalent Circuit of Line Terminated to Transformers Page 6

7 Investigations Findings Magnetic Saturation Characteristics Typical Iron Core Magnetization Curve Page 7

8 Impact on DC Current Injection To Transformers Main Issues of Concern: Transformer/Reactor Saturation - Harmonics Harmonic Currents on the 500 k Side of a 360 M, 500/230 k Transformer with 75 DC Injection From Mitigation of Geomagnetically Induced and DC Stray Currents, EPRI Report EL-3295, December 1983, by J. G. Kappenman, et al. Page 8

9 The Effects of the March 13, 1989 Storm Felt as South as New Jersey Magnetic Field: ~1500 nt/min Page 9

10 ulnerabilities Studies / Model Requirements Modeling Issues The main mechanism of DC current entry into saturable core electrical equipment is via the grounding system of substations and transmission lines Page 10

11 ulnerability Studies / Modeling Requirements Frequency Dependence of Line Parameters Line Model G. J. Cokkinides and. P. Meliopoulos, "Transmission Line Modeling with Explicit Grounding Representation," Electric Power Systems Research, vol. 14, no. 2, pp , pril Page 11

12 Example Parametric Study Magnetic Saturation Characteristics Steady State Direct Current through Transformer Winding From Effects of Geomagnetic Disturbances on Electric Power Systems, EPRI Report EL-7333, ugust 1991, by. P. Sakis Meliopoulos et al. Page 12

13 Example Simulation Results / ulnerability Study Main Issues Concern: Transformer/Reactor Saturation Simulations BUS230BB BUS230B 1 2 XFMR2 SOURCE2 G SOURCE1 XFMR1 2 1 BUS230 BUS230MID GICMID G GIC2 Page 13

14 ulnerabilities Studies / Focus Systems ulnerable System Non-ulnerable System Non-vulnerable/vulnerable system / Series Compensated Line Page 14

15 Impact on Generators G SOURCE1 XFMR1 2 1 BUS230 BUS230MID GICMID BUS230BB BUS230B 1 2 XFMR2 SOURCE2 G Main Issues Concern: Generator Simulations GIC Neutral_DC_Current () Generator Grounded with 1000 ohm Resistor DC Current in Transformer Neutral: 80 Generator Neg Seq Current: 138 peak Generator current THD: 8.4% m m % % Current_Negative_Sequence () Current_Zero_Sequence () Current_THD_Phase_ (%) ms s Page 15

16 Impact on Generators G SOURCE1 XFMR1 2 1 BUS230 BUS230MID GICMID BUS230BB BUS230B 1 2 XFMR2 SOURCE2 G Main Issues Concern: Generator Simulations GIC Neutral_DC_Current () Generator Grounded with 10 ohm Resistor Current_Negative_Sequence () DC Current in Transformer Neutral: m Current_Zero_Sequence () Generator Neg Seq Current: 138 peak m % Current_THD_Phase_ (%) Generator current THD: 8.4% % ms s Page 16

17 Mitigation Methods / Effectiveness Early Warning Systems Monitoring / larming Systems DC Block Systems Resistance Grounding Page 17

18 Mitigation Methods / Effectiveness Warning Systems Important function of SOHO: Geomagnetic Storm Strength Measurement Transmits K - Index The K-Index is a 3-hourly quasi-logarithmic local index of geomagnetic activity relative to an assumed quiet-day curve for the recording site. Range is 0 to 9 The K-Index measures the deviation of the most disturbed horizontal component of the magnetic field. ctive: K=4, Minor Storm: K=5, Major Storm: K=6 or higher Page 18

19 Mitigation Methods / Effectiveness Monitoring / larming Systems MCRODYNE PMU, 1992 First Device Capable of Synchronized Measurements with accuracy of microsecond I GPS ntena Filter Macrodyne PMU Based Harmonic Measurement System PMU Block Diagram GPS Receiver /D Micro processor Phasor data (time stamped) Serial Communication Port Global Time Reference (GPS) symmetric Power System Model New York Power uthority PMU Computer PMU Computer PMU Computer Harmonics Data Concentrator (Located in tlanta) This System is Presently Operational and Participates in the North merican SynchroPhasor Initiative (NSPI) To Control Center NYP Project Launched: 1993, Completed: 1998, Meliopoulos & Cokkinides DD Bulletin Board System GIC Data Concentrator Located at NYPP B. Fardanesh, S. Zelingher,. P. Sakis Meliopoulos, G. Cokkinides and Jim Ingleson, Multifunctional Synchronized Measurement Network, IEEE Computer pplications in Power, olume 11, Number 1, pp 26-30, January Page 19

20 Mitigation Methods / Effectiveness Harmonic Monitoring Macrodyne PMU Based Harmonic Measurement System Detects GIC by: (a) harmonic signature and (b) neutral direct current measurement Harmonic Signature Due to GIC Neutral DC Monitoring - Hall Effect CT B. Fardanesh, S. Zelingher,. P. Sakis Meliopoulos, G. Cokkinides and Jim Ingleson, Multifunctional Synchronized Measurement Network, IEEE Computer pplications in Power, olume 11, Number 1, pp 26-30, January Page 20

21 Mitigation Methods / Effectiveness DC Blocking Devices Page 21

22 Mitigation Methods / Effectiveness Resistance Grounding Page 22

23 Thank you for your ttention Questions? Page 23