Paul Myrda - EPRI &

A.P. Meliopoulos and G. J. Cokkinides - Georgia Tech

October 21, 2014, Houston, TX

Dynamic State Estimation Based Protection: Laboratory Validation

2 © 2014 Electric Power Research Institute, Inc. All rights reserved.

Contents

• Background and Motivation • Long Term Objectives & Vision • Present Relaying Technology • The Setting-less Protection Approach • Implementation / Examples • Applications • Other Benefits • Substation Based State Estimation • Conclusions

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Background and Motivation

• Protective Relay Setting has become Very Complex • New Power Electronic Resource Interfaces Exhibit Fault

Currents Comparable to Load Currents • Detection and Locating of Some Faults is Difficult leading to

Gaps in Protection. • No Substation Level view of Protection • Modeling Errors Play a Major Role in many Control Failures

Wide Area Blackouts • Asset Management is Painful

NERC: #1 Root Cause of System Disturbances

is Protective Relaying

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Long Term Objectives / Vision

• Objective • Reduce Complexity • Minimize the “Coordination Role” of the engineer

• Vision • Develop New Dynamic State Estimation Protection Method

• Establish a “GateKeeper” Device – Transmits the Validated Model Upstream (other

substations, control center, enterprise, etc.) • Develop a fully automated protection, control and operation infrastructure

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Present Relaying Technology

Key Features • Process Bus / Station Bus /

Point to Point • Mimic E/M Relays • More Functions • Increased Complexity • Protection Dependability? • Protection Security? • Protection Gaps?

NOTE: Protection Functions and Algorithms Mimic E/M Relays. New Technology Capabilities are Grossly Underutilized

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The Setting-Less Protection Method

In Search of Secure Protection: Setting-less Protection can be viewed as Generalized Differential protection

Analytics: Dynamic State Estimation (systematic way to determine observance of physical laws)

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Setting-less Protection Approach

1. Measure/Monitor as Many Quantities as Possible and Use Dynamic State Estimation to Continuously Monitor the State (Condition, Health) of the Zone (Component) Under Protection. Identify bad data, model changes, etc.

2. Act on the Basis of the Zone (Component) State (Condition, Component Health).

3. Advantage: No need to know what is happening in the rest of the system – no coordination needed.

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Implementation Overview

• The Component is represented with a set of Differential Equations (DE)

• The Dynamic State Estimator fits the Streaming Data to the Dynamic Model (DE) of the Component

• Object Oriented Implementation

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Challenges

1. Perform the Analytics at time less than (2ts)

2. Robust Operation of DSE requires accurate zone model

3. GPS Synchronized Measurements simplify Dynamic State Estimation (for linear zones it becomes a direct method)

Typical Sampling Rates ts = 0.1 ms to 0.5 ms

Example: Data Acquisition is performed 4 ks/s Dynamic State Estimation is performed 2,000 times per sec.

Implementation – Calculation Time

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Protection Zone

• 115 kV, 48 MVAr capacitor bank

Event

• A single phase to ground fault at 2.2 seconds and duration 0.5 seconds at the location designated “External Fault”.

• An internal fault in the capacitor bank occurs at 3.0 secs (fault shorted cap cans of phase C, see figure). Fault changes the net capacitance of phase C from 4.8 μF to 2.4 μF.

G

1 2

G

1 2 1 2

GEN CAPBNK

CAP1GUNIT2

JCLIN

E3

LINE

LINETEE

LOAD04

SOURCE1

SOURCE1-T

TXFMRHIGH

TXFMRLO

W

XFMR2H

XFMR2L

YJLINE1

YJLINE2

Relay Inputs (Measurements): • Voltage of phase A-G • Voltage of phase B-G • Voltage of phase C-G • Voltage at neutral point • Current of phase A • Current of phase B • Current of phase C

External Fault Capacitor Bank

Internal Fault

Capacitor Bank

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External Fault Internal Fault

Capacitor Bank

125.8 kV

-164.9 kV

Actual_Measurement_Voltage_CAPBANK_A (V)Actual_Measurement_Voltage_CAPBANK_B (V)Actual_Measurement_Voltage_CAPBANK_C (V)Estimated_Actual_Measurement_Voltage_CAPBANK_A (V)Estimated_Actual_Measurement_Voltage_CAPBANK_B (V)Estimated_Actual_Measurement_Voltage_CAPBANK_C (V)

722.9 A

-934.0 A

Actual_Measurement_Current_CAPBANK_A (A)Actual_Measurement_Current_CAPBANK_B (A)Actual_Measurement_Current_CAPBANK_C (A)Estimated_Actual_Measurement_Current_CAPBANK_A (A)Estimated_Actual_Measurement_Current_CAPBANK_B (A)Estimated_Actual_Measurement_Current_CAPBANK_C (A)

100.00

0.000

Confidence-Level

1.000

0.000

Trip

2.933 us

1.512 us

Execution_time_average (s)

March 11, 2014 - 10:46:04.710584 March 11, 2014 - 10:46:06.145781

3Φ Voltage

3Φ Current

Confidence

Trip Signal

Calculation Time

No Trip Trip

Similar Characteristics

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Protection of multi-section Lines Protection Zone

500 kV Transmission Line (indicated as “Monitored Line”)

Event • A phase A-C fault at 0.5 secs

with duration of 0.5 secs at the location indicated as “External Fault”.

• A high impedance (2 kohms) phase A-G fault at 1.3 secs, at the location indicated as “Internal Fault”.

Relay Inputs (Measurements) • Three-phase voltages at both

terminals • Three-phase currents at both

terminals

External Fault

Internal Fault

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External Fault Internal Fault 10.11 kA

-10.90 kA

Actual_Measurement_Current_TABL_A (A)Actual_Measurement_Current_TABL_B (A)Actual_Measurement_Current_TABL_C (A)Estimated_Actual_Measurement_Current_TABL_A (A)Estimated_Actual_Measurement_Current_TABL_B (A)Estimated_Actual_Measurement_Current_TABL_C (A)

418.8 kV

-432.8 kV

Actual_Measurement_Voltage_TABL_A (V)Actual_Measurement_Voltage_TABL_B (V)Actual_Measurement_Voltage_TABL_C (V)Estimated_Actual_Measurement_Voltage_TABL_A (V)Estimated_Actual_Measurement_Voltage_TABL_B (V)Estimated_Actual_Measurement_Voltage_TABL_C (V)

100.00

0.000

Confidence-Level

1.000

0.000

Trip

41.15 us

29.83 us

Execution (s)

January 25, 2014 - 20:08:30.127224 January 25, 2014 - 20:08:31.349990

No Trip Trip

Protection of multi-section Lines

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Protection of Saturable Core Transformers

Protection Zone

14.4/2.2kV, 1000 kVA single-phase saturable-core transformer

Event

• A 800kW load is connected at 0.72 secs to the transformer (generates inrush currents).

• A coil to ground fault at 1.52 secs. The fault location is 5% from neutral.

Relay Inputs (Measurements) • Voltages at both sides • Currents at both sides • Temperature measurements at

selected points

1 2

1-PhG

FAULT

LINE LOADSOURCE XFMRH XFMRL

Internal Turn-Ground Fault

Inrush Current

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20.22 kV

-20.21 kV

Actual_Measurement_Voltage_XFMRH_A (V)Estimated_Actual_Measurement_Voltage_XFMRH_A (V)

129.3 A

-82.12 A

Actual_Measurement_Current_XFMRH_A (A)Estimated_Actual_Measurement_Current_XFMRH_A (A)

100.00

4.474 p

Confidence-Level

1.000

0.000

Trip or Not Trip

107.0 %

46.19 m%

Differential_Operation_Index (%)

July 14, 2014 - 22:36:58.315318 July 14, 2014 - 22:36:59.789669

Setting-Less Protection - No Trip Setting-Less Protection - Trip

Differential Protection - Trip

Differential Protection – No Trip

Inrush Current Internal Fault

Protection of Saturable Core Transformers

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Setting-less Protection Applications

• The following application have been successfully simulated in the lab environment: – Capacitor Bank Protection – Transmission Line Protection – Transformer Protection – Doubly Fed Induction Machine Protection – Saturable Core Reactor Protection – Distribution Line Protection

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Experimental Setup Block Diagram

Experimental Setup PC with D/A Hardware

Amplifiers (3)

Hardfiber (2)

PCIe Cards (2)

Protection PC (1)

Laboratory Implementation

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Laboratory Results Example

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A Ubiquitous System for Perpetual Model Validation

Protection is Ubiquitous • Makes Economic Sense to

Use Relays for Distributed Model Data Base

• Capability of Perpetual Model Validation

Other Benefits

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Time Phasor Domain Transition

Overall Model Flow Substation Automation

Vision: Substation Based State Estimation Control Center State Estimation

Advantages • Detection of Hidden Failures

• Centralized Substation Protection

• Automated Protection Coordination

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Summary

• Setting-less Protection has been proven in a lab environment in six application areas

• Prototype installation at NYPA under a NYSERDA grant • Multiple secondary benefits

– Model Validation – Detection of Hidden Failures – Distributed State Estimation – Applications

Thank You!

Together . . . Shaping the Future of Electricity