March 27, Power Systems. Jaime De La Ree ECE Department

Transcription

1 March 27, 2015 Power Systems Jaime De La Ree ECE Department

2 Early History The first generator was developed by Michael Faraday in 1831 John Woolrich patents magneto-electric generator in 1842 (for electrotyping) California Electric Light Co. supplies power for arc lighting 1879 First power stations in London and New York in the Pearl Street station supplied 59,000 after starting with 2300 bulbs

3 Power System Elements Generators - Input Loads - Outputs Lines Ties Gens to Loads Operating Characteristics & Constraints Power Balance KVL & KCL Line flows based on Impedances No large-scale storage Manufacture as we need it

4 Operation Key ingredients: Economics and Reliability Economics Large Optimization Generator Scheduling and Commitments Cost minimization Reliability No violations of voltage levels, Frequency excursions, power flows, Continuous monitoring Control

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6 Blackouts 1965 North East of the USA 1977 New York City blackout 1989 Geomagnetic storm affected Hydo-Quebec 1996 High summer heat Western North America and parts of Mexico 2003 Northeast Blackout 2003 Malaysia 2003 Hurricane Isabel 2003 Sweden and Denmark 2003 Italy

7 Blackouts System studies Many recommendations EMS Centers SCADA Supervisory Control and Data Acquisition Power Flows and Power Injections (Real and Reactive) State Estimators Z = f(x) Z Mediciones x - State 7

8 Static State Estimator System is static while scan is made Technology Limitation Non-Linear Iterative Bad Data rejection- important 8

9 Static State Estimator State of the system EMS Contingency Analysis Operator makes topological and/or operational changes to move the system to a more secure operating point Generation Dispatch 9

10 Static State Estimator Field Sensors IEDs, PMUs SCADA EMS State Estimation Applications 10

11 Static State Estimator Data Collection SCADA (Supervisory Control and Data Acquisition) State of the system EMS Large and Complex Harware-Software Systems Operator makes topological and/or operational changes to move the system to a more secure operating point Generation Dispatch 11

12 A New Paradigm: PMU Synchrophasor Synchronized Phasor Measurement GPS 2 45 PMU Phasor Measurement Unit

13 Phasors Inputs Analog filters Sampled data Phasors Relay Logic Digital filtering Current and voltage magnitudes for relaying require computation of phasors Want to respond to symmetrical rms quantities in the presence of harmonics and other noise Impedance relaying requires complex phasors from which impedance can be calculated 13

14 Phasors - Definition θ Imaginary θ Real t=0 The starting time defines the phase angle of the phasor. This is arbitrary. However, differences between phase angles are independent of the starting time. 14

15 Sampling, Fourier Input signal Data samples cosines sines sin and cos functions x n x n-1.. x 1 t Phasor X = ---Σ x k (coskθ - j sinkθ) 2 N 15

16 Non-Recursive Calc. θ 1 θ 2 θ 2 = θ 1 + kφ t θ 1 The non-recursive phasor rotates in the forward direction, one sample angle per sample. 16

17 Recursive Calculation θ 1 θ 2 = θ 1 t θ 2 = θ 1 θ 1 The recursive phasor remains fixed if the input waveform is constant. 17

18 Why are they Important? Captures Voltage/Current magnitude and angle All units are referenced to a common time All information is time tagged High Resolution data phasors per second 18

19 PMU A new view

20 PMU A new view

21 WAMS Synchronous Measurements GPS Time error in Nano-Sec Time Tagged samples Data Concentrators 21

22 Aplicaciones Monitoring Information to Operators Control Process and Equipment optimal Protection. 22

23 What is it? An adaptive protection scheme is: Settings Alarms Triggering/Threshold values Security vs Dependability Stress vs Capacity Becomes more attuned with he prevailing conditions of power system 23

24 Adaptive Protection I know.. Most likely we are going to have arguments with field protection engineers. 24

25 Why? Traditional protection schemes/systems are based on pre-determined studies: Fixed Loads Static topologies Known contingencies Hidden Failures are 25

26 How? Advances in Monitoring Systems: Synchronous Wide Area Microprocessor-Based IEDs Store Process Communicate All in a common time 26

27 Where? Possibly one of the most interesting questions Criticality Generators Lines Loads 27

28 Generators Loss of Excitation protection 28

29 29 LOF Relay

30 30 Lines

31 31 Lines

32 32 LODF

33 Changes of Topology The problem here is load 33

34 34 Changes of Topology

35 35 Changes of Topology

36 36 Changes of Topology

37 Loss of Generation Load-Flow Solution The re-distribution is incorrect: The swing bus will shoulder all the necessary change. Generation Loss Associated Losses Inertial re-dispatch Long-Term the solution may be appropriate. Short-Term the solution neglects the electrical distances 37

38 38 Where are you?

39 39 Where are you?

40 Loss of Generation Bus Admittance Matrix Zero entry at ij indicates that there is no connection between node i and node j Kron Reduction! # # " I g I n $! & & = Y gg Y # gn # % Y ng Y " nn $! & & * # # % " V g V n $ & & % 40

41 Loss of Generation Let In=0! # "# I g 0 $! & %& = Y gg Y # gn # Y ng Y " nn $! & & * # # % " V g V n $ & & % I = " Y Y g # Y 1 Y gg gn nn ng $ % V g 41

42 42 IEEE 39 Bus System

43 43 Loss of Generation

44 44 Gen 32 Off

45 45 Gen 32 Off

46 46 Gen 7 Off

47 47 Gen 7 Fuera

48 48 Gen 7 Fuera

49 Vision Deployment Challenge High SGIG ac3vity (9-12 projects) Medium SGIG ac3vity (5-8 projects) Low SGIG ac3vity (1-4 projects) No SGIG ac3vity Post- event Analysis Wide Area Monitoring and Visualiza3on Transmission Pathway and Conges3on Management Model Valida3on Oscilla3on Detec3on Voltage Stability Monitoring Frequency Stability Monitoring Detec3on of Imminent Disturbance Cascading Disturbance Detec3on and Alarming Automated Controls DG and Renewables Integra3on State Es3ma3on Islanding and Restora3on Source: DOE Controlled System Separa3on 1-2 Years 2-5 Years >5 Years SGIG=smart grid investment grant

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