Basics of Power System Control and Protection

Basics of Power System Control and Protection

A. P. Sakis Meliopoulos Georgia Power Distinguished Professor School of Electrical & Computer Engineering Georgia Institute of Technology NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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School of Electrical and Computer Engineering Chairman Chairman (interim) (interim) Dr. Dr. Douglas Douglas B. B. Williams Williams

Associate Associate Director Director Graduate Graduate Affairs Affairs

Associate Associate Director Director Undergraduate Undergraduate Affairs Affairs

Computer Computer Engineering Engineering

Microelectronics Microelectronics

Digital Digital Signal Signal Processing Processing

Modern Modern Optics Optics

Electric Electric Power Power

Systems Systems and and Controls Controls

Electromagnetics Electromagnetics

Telecommunications Telecommunications

Electronic Electronic Design Design and and Applications Applications

Bioengineering Bioengineering

Associate Associate Director Director

Associate Associate Director Director

NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Undergraduate Curriculum ECE3070 ECE3070

Electromechanical Energy Conversion

ECE4320 ECE4320

Power System Analysis

ECE4321 ECE4321

Power System Engineering

ECE4330 ECE4330

Power Electronics

ECE4325 ECE4325

Electric Power Quality


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Graduate Courses in Power Systems ECE6320 ECE6320

Control and Operation of Power Systems

ECE6321 ECE6321

Power System Stability

ECE6322 ECE6322

Power System Planning

ECE6323 ECE6323

Power System Relaying

ECE8843 ECE8843

Topics in Electric Power Computational Intelligence in Power Systems


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Graduate Courses in Power Electronics

ECE6330 ECE6330

Power Electronic Devices & Subsystems

ECE6331 ECE6331

Power Electronic Circuits

ECE6335 ECE6335

Electric Machinery Analysis and Design

ECE6336 ECE6336

Dynamics & Control of Electric Machine Drives


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Continuing Education Power Systems Certificate Program Core Core Courses Courses •Power •Power System System Relaying: Relaying: Theory Theory and and Application Application •Modern •Modern Energy Energy Management Management Systems Systems •Integrated •Integrated Grounding Grounding System System Design Design and and Testing Testing •Grounding, •Grounding, Harmonics, Harmonics, & & Electromagnetic Electromagnetic Influence Influence Design Design Practices Practices •Power •Power Distribution Distribution System System Grounding Grounding and and Transients Transients •Power •Power Electronic Electronic Devices, Devices, Circuits, Circuits, and and Systems Systems Elective Elective Courses/Conferences Courses/Conferences •Fault •Fault and and Disturbance Disturbance Analysis Analysis Conference Conference •Georgia •Georgia Tech Tech Protective Protective Relaying Relaying Conference Conference

-

All Courses are Coordinated by the Department of Professional Education

-

All Courses are Offered Annually

-

Academic Administrator: A. P. Meliopoulos


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Present State of the Art: C&O and P&C Model Based Control and Operation

Control & Operation Real Time Model State Estimation

Applications Load Forecasting Optimization (ED, OPF) VAR Control Available Transfer capability Security Assessment Congestion management Dynamic Line Rating Transient Stability EM Transients, etc. Visualizations

Markets: Day Ahead, Power Balance, Spot Pricing, Transmission Pricing (FTR, FGR), Ancillary Services

Protection & Control Component Protection generators, transformers, lines, motors, capacitors, reactors

System Protection Special Protection Schemes, Load Shedding, Out of Step Protection, etc.

Communications Substation Automation, Enterprize, InterControl Center

The Infrastructure for Both Functions is Based on Similar Technologies: Thus the Opportunity to Merge, Cut Costs, Improve Reliability Integration of New Technologies NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Power Systems Operation Main Objectives

Tools

REGULATION Frequency Voltage Net Interchange Pollutants

DATA AQUISITION SYSTEM SUPERVISORY CONTROL STATE ESTIMATION ANALYSIS OPTIMIZATION CONTROL

SECURITY ECONOMICS Net Interchange Pollutants Power Transactions IPPs Energy Balance Market Ancillary Services


Restructuring POWER MARKET (SMD) TRANSMISSION TARRIFS (FTR,FGR) CONGESTION MANAGEMENT ERO (Electric Reliability Organization)

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Component (Zone) Protection G+GSU Backup Bus

Line 20 kV

230 kV

Xfmr

• • • • • • •

Generators Transformers Buses Transmission Lines Motors Capacitor Banks Reactors, etc.

12kV

FDR Zone

R

Radial NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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System Protection Out of Step (Transient Stability)

Transient Voltage Collapse Reactance Grounded Gen Reactance Grounded Gen

800 MVA-15 kV

800 MVA-15 kV

X1=15.5%,X2=18%,X0=9%

X1=15.5%,X2=18%,X0=9%

Va = 8.400 kV 1

G

2

Va = 61.99 kV

Va = 63.01 kV BUS10

Illustration of Two Power System Swings: (a)Stable – Out of Step Relay Should not Operate (b)Unstable – Out of Step Relay Should Operate

Va = 42.02 kV BUS-MID

Generator Angle 52 Degrees

Special Protection Schemes Special Protection Schemes are Protective Relaying Functions Concerned with the Protection Against Special System Conditions that May Lead to Catastrophic Results. These System Conditions are Determined with Extensive Studies of Specific System Behavior. Using this Information a SPS is designed that monitors the System and When the Special System Conditions Occur (Recognition Triggers) the System Operates (Automatically or with Operator Review and Action)

SOURCE-A

BUS20 1

2

Va = 8.238 kV BUS30

G

2x47.4 mile 115 kV Transmission Line Generator Angle -49 Degrees

Illustration of Voltage Collapse Near the Center of a Stable System Swing Voltage Transitions Are Slow – Undervoltage Protection Should not Operate

Load Shedding – Frequency / Voltage


A System Disturbance May Create Generation-Load Imbalance Leading to Sustained Frequency Decline. This Condition, if not Corrected, May Lead to Equipment Damage. The Condition Can be Temporarily Corrected by Load Shedding Until Additional Generation can be Dispatched. Similarly, a Disturbance May Create Sustained Voltage Problems. These problems Can be Also Corrected by Load Shedding

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Control & Operation


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Modern Energy Management System Functional Diagram DATA AQUISITION AND PROCESSING SUBSYSTEM

ENERGY/ECONOMY FUNCTIONS SUBSYSTEM Load Forecast Load Forecast Unit Commitment Power Bids Ancillary Services

State Estimation Automatic Generation Control

Displays

External Equivalents

Congestion Management Transmission Valuation

GPS Synchronized Measurements

Network Topology

Economic Dispatch

Power Balance Market

SCADA Measurements

Parameter Estimation

Economic Interchange Evaluation

SECURITY MONITORING AND CONTROL SUBSYSTEM Optimal Power Flow Security Dispatch Environmental Dispatch

Emergency State

Emergency Controls

Security Monitoring Normal State

Contingency Analysis VAR Dispatch

Extremis State

Restorative Controls

Insecure State

Preventive Controls


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OVERVIEW OF ENERGY MANAGEMENT SYSTEMS Data Acquisition and Processing Subsystem G1

G2

MW Flow Measurement MVAR Flow Measurement kV Measurement Disconnect Switch Status Breaker Status

RTU

Contact Inputs Analog Inputs Contact Outputs Analog Outputs


New Technology GPS Synchronized Measurements (Phasors)

Communication Link with Control Center

Data

RTU Commands

Master Station

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Network Configurator Example

Breaker Oriented Model AutoBank 500kV/230kV G1

SG1


AutoBank 500kV/230kV

G2

SG2

Bus Oriented Model

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State Estimator G1

• MEASUREMENTS:

G2

1

• STATE:

3 T1 2

• FORMULATION:

T2

• SOLUTION:

4

L1

Interconnection

Interconnection

Traditional State Estimation

L3 L2

5 T1

MW Flow Measurement MVAR Flow Measurement kV Measurement Transformer Tap Measurement

Centralized Procedure

6

Observability Bad Data Detection/ID/Rejection Parameter Estimation NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Technological Developments


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The OLD and the NEW Circuit Breaker

CT

CCVT

Relays

P

Circuit Breaker

CT

CCVT

Q

I

V

IED-Relay Comm Link


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SCADA Evolution Indicator

Control

SCADA circa 1923 Independent of Protection To Data Base

Remote Access

Control Center User Interface

Communication Standards

Encoder Decoder

GPS

Communications Terminal RTU

IED

Disturbance Recorders

Relays

SCADA circa 2003 SCADA


Communications Terminal

Local Computer

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Project Background: Substation Architectures: SmartGrid

Protection, Control, Communications

Physical System

GE Hardfiber System NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

Industry Direction: Single Data Acquisition System for Protection, Control, and Operations 1.20

Important New Technology GPS-Synchronization History of GPS-Synchronized Measurements NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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History of GPS-Synchronized Measurements

GPS Satellite System Initiated 1989, Completed 1994

The Antikythera Mechanism 87 BC


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Important Milestones 1970: First Computer Relay (PRODAR, Westinghouse, Gilcrest, Rockefeller, Udren) 1984: First Commercial µProcessor Based Relay (SEL) 1989: GPS Signal Becomes Commercially Available 1990-91: Phasor Measurement System (Arun Phadke) 1992: Phasor Measurement Unit (PMU) (Jay Murphy, Macrodyne) NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Arun Phadke’s Arun Phasor Phadke’s Measurement PMS System Block BlockDiagram DiagramPublished Publishedby byArun ArunPhadke Phadke

Vintage 1990-92 Vintage 1990-91 several units were soldUnits to Several AEP, WereNYPA, Sold to others

AEP, NYPA, others

CHARACTERISTICS

Time TimeAccuracy AccuracyWas WasNever NeverMeasured Measuredor orReported. Reported. Multiplexing and Design Suggest Very High Multiplexing and Design Suggest Very HighTiming TimingError Error Estimated Time Precision: 100 us, 2 degrees at 60 Hz Estimated Time Precision: 100 us, 2 degrees at 60 Hz NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

•

Analog Filter with Cutoff Frequency of 360Hz

•

Sample & Hold A/D Technology with Analog Multiplexing

•

12 bit S&H A/D 720 s/s

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Macrodyne 1620 PMU Released to Market January 1992 Jay Murphy (Macrodyne) Was First to Introduce Term PMU: Phasor Measurement Unit Input Protection & Isolation Section

GPS Antenna A/D Converter (Σ∆ Modulation)

Optical Isolation

Digitized Data 2880 s/s

CHARACTERISTICS GPS Receiver

Optical Isolation

PLL

Sampling Clock

Input Protection & Isolation Section

A/D Converter (Σ∆ Modulation)

Optical Isolation

Master Workstation


µP

Optical Isolation Digitized Data 2880 s/s

•

Individually GPS Sync’d Channels

•

Common Mode Rejection Filter with Optical Isolation

•

16 bit A/D Σ∆ Modulation

IRIGB

Memory

Analog Inputs V : 300V I : 2V

1PPS

Display & Keyboard RS232 Data Concentrator (PC)

Time TimeAccuracy Accuracy11µs µs 0.02 0.02Degrees Degreesat at60 60Hz Hz 1.25

Distributed Dynamic State Estimation Implementation PMU Technology Enables Distributed SE IED Vendor D

Measurement Layer

i1(t) i2(t)

Burden

Physical Arrangement Data Processing

Instrumentation Cables

Attenuator

FireWall

PMU Vendor A SuperCalibrator

Attenuator

v2(t)

Anti-Aliasing Filters PMU Vendor C

Burden

Data Flow LAN

v1(t)

Relay Vendor C

LAN

Current Transformer

v(t)

Potential Transformer

i(t)

Encoding/Decoding Cryptography

Phase Conductor

Data/Measurements from all PMUs, Relays, IEDs, Meters, FDRs, etc are collected via a Local Area Network in a data concentrator. The data is used in a dynamic state estimator which provides the validated and high fidelity dynamic model of the system. Bad data detection and rejection is achieved because of high level of redundant measurements at this level. NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Numerical Results – B-G Plant


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Transient Stability Monitoring The dynamic state estimator is utilized to predict the transient stability or instability of a generator. The dynamic state of the system provides the center of oscillations of the generator swing. From this information the potential energy of the generator is computed as a generalization of the basic energy function method. The total energy of the generator can also be trivially computed once the potential energy has been computed. The total energy is compared to the potential energy of the generator – if the total energy is higher than the peak (barrier) value of the potential energy this indicates that the generator will lose its synchronism (transient instability). It is important to note that this approach is predictive, i.e. it identifies a transient instability before it occurs. The figures provide visualizations of generator oscillations and the trajectory of the total energy superimposed on the system potential energy.


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Energy Management Systems Hierarchy of Scheduling Functions Level 1: Load Forecasting Unit Commitment Emissions Control Economy Purchases Level 2: Economic Dispatch Environmental Dispatch Economic Interchange Evaluation Optimal Power Flow Transfer Capability Day-Ahead Scheduling Spot Market Scheduling Level 3: Automatic Generation Control - Frequency Control - Interchange Control - Transactions Control - Inadvertent Power Flow Control NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Generating Unit Control Schemes Schematic Representation Tramsmission System and Load Prime Mover

G Vg

Governor G(s)

Pg

Tie Line

f

Exciter

fsched

f

-

+ Vref

+

Σ + PSS D(s)

f Σ -

Pg

Σ

Bias Bf

+

Psched

+

Pg -

Σ

+

K(s)

Σ

+

f L(s)


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Net Interchange Control G

Area 1

G

Area 3

Vi e jδi

G

G

G

ACE = P

Area 4

G

Area 2 G

Area Control Error (ACE)

ACE = ∆Pint + B∆f

∆Pgi = a i ACE NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

G

G

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Economic Scheduling Functions Hierarchical Structure A

Resource Scheduling (weeks) Mid Term Load Forecast Units out for maintenance Fuel Management Weekly hydro energy usage

B

Unit Commitment (hours/Days) Short Term Load Forecast List of committed units Hourly hydro energy usage Interchange schedule

C

Economic Dispatch (minutes)

Security Dispatch Economic Base Points Participation Factors

D

Automatic Generation Control (seconds)

Pdesi , i =1,2,...,n NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Economic Dispatch G1

• MEASUREMENTS

G2

1

• COST

3 T1

• FORMULATION

T2

• SOLUTION 2

4

L1

Interconnection

Interconnection

L3 L2

5 T1


6


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Optimal Power Flow G1

G2

• MEASUREMENTS 1

3

• STATE

T1 2

T2

• CONTROLS • FORMULATION

4

L1

Interconnection

Interconnection

• SOLUTION

L3 L2

5 T1


6


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SYSTEM SECURITY

NORMAL and SECURE System Optimization

(Congestion Management) Power System Operating States

D,O Preventive Controls


RESTORATIVE System Security

D,O Emergency Controls EXTREMIS System Security


NORMAL but VULNERABLE/INSECURE Optimization/Security

D,O

Emergency Controls

Corrective Controls EMERGENCY System Security

D,O

D,O Transition Due to Disturbances Transition Due to Control Action


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Energy Management Systems Hierarchical Structure System Power Production and Control (SPPC) Operations Coordination Office (OCO)

Regional Dispatch Center (RDC)

Substation

Power Plant UCE Vexc


Power Plant Controls

Psched fsched ACE Vsched

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New Challenges: Wind/PV Farm Characteristics Types 1 and 2 are Not Used for Large Projects Types 3 and 4 Limit Fault Currents to About 120% of Nominal Current

Proposed Proposed Requirements Requirements –– NERC NERC PRC-024, PRC-024, >20 >20 MVA MVA or or >75 >75 MVA MVA Total Total


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Renewables and Uncertainty Solar is Available During High Price/Cost Hours Small Storage can provide huge add-on value to solar projects Better capacity factor than other renewables (70 to 80%)

Wind Availability is Highly Volatile and Patterns May be Opposite to Grid Needs (i.e. CA) Large Storage Schemes are needed to coordinate economic usage of wind energy and to provide add-on value Very small capacity factor (10 to 25%)

Large Wind Swings


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Energy Management Systems: Evolution

Control and Operation of Power Systems is Driven by (a) Legislative action (b) Economics (c) Technical constraints The envelop is always moving because of technological advancements ERO Focus: Operational Reliability NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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History of Utility Regulatory Legislation Federal Power Commission • PUHCA – 1935 (Public Utility Holding Company Act) Federal Energy Regulatory Commission (1977) • PURPA – 1978 (Public Utility Regulatory Policies Act) • Clean Air Act – 1990 • Energy Policy Act – 1992 • Orders 888 & 889 – 1996 (1 OASIS ) • CECA – 1998 (Comprehensive Electricity Competition Act) • Order 2000 • SMD – Standard Market Design • US Energy Policy Act, 2005 (provides authority to enforce reliability) NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Visualization & Animation University of Illinois/Georgia Tech (PSERC Project)

G e n e ra to r A n im a tio n - U n it C a p a b ility U n it N a m e

Qg

R o tor H e ating

Pg

L ow V o lta ge

S e n s itiv itie s

d P g /d P d Q g /d P d V g /d P

0

1

2

3

4

0

1

2

3

4

0

1

2

3

4

Large Scale Systems Performance - Model Hierarchy NSF/ECEDHA Education Workshop Georgia Tech GLC, Atlanta, Georgia, July 9-12, 2011

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Energy Management Systems Information Systems and Standards OASIS

Open Access Same-Time Information System

UCA

Utility Communication Architecture

ICCP

Inter-Control Center Communications Protocol

CCAPI

Control Center Application Program Interface

CIM

Common Information Model

IEC61850 Evolution of the UCA C37.118 Synchrophasor Data


1.43

Active Future Distribution Systems (with distributed energy resources – solar, wind, PHEVs, fuel cells,…). Smart Grid technologies: Distributed Monitoring, Control, Protection and Operations system. Target Speeds 10 times per second Functions: (a) Optimal operation of the distribution system under normal operating conditions, (b) Emergency management in cases of faults and assist the power grid when needed, (c) Assist Voltage recovery, (d) Assist cold load pickup, (e) Balance Feeder, (f) etc., etc.


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Evolution, Naxos Island, Greece June 25, 2011


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Basics of Power System Control and Protection

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