Modern Trends/Developments in Protection &

Modern Concepts Used for Line Protection with M1 & M2 Relays

Training on Power System Protection ERPC 11-15 May, 2015

Dr. R. NagarajaManaging Director

PRDC

Substation and Interface level

Wide Area Protection

Testing Environment

Setting calculation and storage

Disturbance Analysis

Line Protection - Trends

Agenda

Substation and Interface Level

Substation wiring cost is being reduced drastically with IEC 61850

Interoperability between product and applications

Overall substation management and efficiency improvementGoose messaging is being used to achieve better adaptability in settingSetting and relay operation waveform upload/download remotely

Substation Level

Source : ABB Brochure

Optical CT usage has improved the measurement/sensing and minimized the CT

saturation related errors

Wide Area Measurement and Protection

Distance Protection

Zone 1 = 85% of AB = 0.85*10 = 8.5 ohm

Zone 2 = AB+50% of BC (shortest line) =10+0.5*10 =15 ohm

Zone 3 = AB+BC+20% of CD (longest line) = 10+10+0.2*10 =22 ohm

A B C D

E

F

R10 Ω 10 Ω 10 Ω

20 Ω

5 ΩZone 1

Zone 2

Zone 3

Distance relay zone settings

Multi-terminal LinesA B

C

D

R10 Ω 10 Ω

ET

10 Ω

10 Ω

10 Ω

IA IB

Ic

A

TBBATA

R

R

I

)Z*I()Z*(I

I

V

A

TBCAATA

R

R

I

Z*)II()Z*(I

I

V

A

CTBTBAT

R

R

I

IZZZ

I

V

A

CTBTBAT1 I

IZZZK1 Zone

BD2A

CTBTBAT Z*K

I

IZZZ2 Zone

DE3BDA

CTBTBAT Z*KZ

I

IZZZ3 Zone

Multi-terminal Lines

Without infeed( Ic=0)

With infeed( Ic=IA)

Weak infeed( Ic=0.5*IA)

Strong infeed( Ic=2*IA)

Zone 1 (Ω) 17 25.5 21.25 34

Zone 2 (Ω) 25 35 30 45

Zone 3 (Ω) 32 42 37 52

Out of step relay

Traditional relays use zones to determine whether electromechanical swing will lead to instability or not.

Out of step relay

Large number of simulation need to be carried out to determine relay settings.

Conventional settings are unsatisfactory and results in mis-operation because system changes quickly and tested swings are different from actual.

Adaptive settings are required to cope up with such problem.

Adaptively changing the timer settings.

Adaptive Zone settings.

New approach is suggested using equal area criteria.

Implemented on Florida-Georgia interface project undertaken by Virginia Technology.

Out of step relay

Pm1

Y10

Pm2

Pe1 Pe2

Y20

11 δE 22 δE Y12

γ)sin(δPPPdt

δdM maxcm2

2

rotors twoof inertia ofmoment are M and M and where 2121

21

21

MM

M*MM

21

m21m12m MM

PM-PMP

21

2222111

212

c MM

GEM-GEMP

2/)MM(

tan)MM(

21

1221

)M(M

)cos(2θM2MMMYEEP

21

12212

22

11221max

Out of step relay

Accelerating area must be smaller than decelerating area for system to be transient stable.

Equal area criteria

Back up Protection

Load encroachment

Back up zones of distance relay are prone to tripping due to load encroachment.

Modification in relay characteristics is required.

Same can be achieved by using phasor measurement unit.

Back up Protection

Assume zone 3 of relay A has picked up.

Determine for any zone 1 fault in other stations using PMU.

If none of them exist restrain zone 3 of relay since it might have picked up due to loadability in the system.

A

Event Analysis and Oscillation Monitoring Schemes using PMU data

Distance Relay Concerns• Parallel line

operation• Mutual coupling • In-feed • Power swing and

load encroachment

Event Analysis and Oscillation Monitoring Schemes using PMU data

Need Introduction of PMU has open avenues for various power system applications

Major challenge is to analyze the group of PMUs and correlate the data with system events

Utilizing the higher sampling data to analyze more critical system behavior such as low frequency oscillations

Justification The scheme focuses on generic architecture for PMU applications.

Event analysis is an important task which can help the data to segregate into Disturbance data or Ambient data.

Testing Environment

Testing Trend

Steady-state calibration

Dynamic-state simulation

Transient simulation

End-to-end testing.

Source: Doble Project at PRDC

Source: Kinetrics Interoperability Lab

Use of Real Time Digital Simulation Environment for special protection systems

(SPS) and critical lines distance scheme testing is highly recommended

Setting Calculations & Storage

Protection Database Management System

Protection Setting Calculation Engine

Protection Suite Components

Bus-Branch Model to

Bus-Breaker Model

Protection Suite Components

22

Grid Disturbance

Protection LayerBest Operational Practices

System Planning

Special Protection Systems (SPS)

It is not easy to achieve Grid Collapse!!!

Specific Action following an outage/disturbance

Fast acting and generally without any time delay

Applicable for tie lines tripping, HVDC link tripping, major generation

trippingSaves the system from complete

collapse

23

Hard wired scheme

• On tripping of a specific element/breaker other elements are tripped to get load/generation relief

• Generally ends up in more load shedding or generation curtailment

• Optimal action is not ensured

• At times may not get any relief

Intelligent System

• Ensures optimal load/generation tripping

• Needs system digital and analog information

• Network topology processing program

• Dynamically computes the load or generation to be tripped for any breaker tripping

SPS Implementation - Types

Simulation Environment

Improves the protection settings

Simulates various operating conditions

Helps to re-construct and perform post-mortem analysis

Design of out-of-step and under frequency load shedding schemes

Disturbance Analysis

Automation in Fault Disturbance Data Collection and Analysis

AFAS

Report Manager

Data Collector

Processed File Storage

Inputs from all locations

Server with Database and Engines

Queries from Users

Outputs

DPR, DFR, SCADA ...

Centralized Deployment of Fault Analysis System

Levels of analysis

System Level

Unit Level

Bay Level

Station Level

Station 1

Station 2

Station 3

Station 4

Protection Function

level

Probable Architecture of Fault Analysis System

System ManagerUser Access ManagerConfiguration ManagerCOMTRADE ViewerEngineLoggersReport GeneratorWeb InterfaceOffline Analysis

Fault Analysis System Modules

COMTRADE Viewer

Distance Relay Contour

Case study of AFAS

Power Research and Development Consultants Pvt. Ltd.

Waveform of Phase R Current

Inferences

· Single line ground fault detected

·Fault distance of 286.54 km

·Successful auto reclosure having dead time of 1.09 s

·CT saturated during fault

·CVT is healthy

·Relay operation within limits

Inferences

· Single line ground fault detected

·Fault distance of 286.54 km

·Successful auto reclosure having dead time of 1.09 s

·CT saturated during fault

·CVT is healthy

·Relay operation within limits

System Performance over the period and KPI tracking

Additional Benefits of AFAS

Algorithm level improvement

Improved Technique for Fault location computation and identifying cause of Fault

Need of improved scheme Digital filters are used to compute fundamental component of voltages and currents.

Discrete Fourier transform (DFT) is a popular filtering technique.

The response time of DFT is around one cycle, which is bound to increase if the input is non sinusoidal.

Power system computation can have errors due to variation in filter output.

Information about the cause of fault can render assistance to power system engineers which is not been focused presently

Justification Scheme based on Prony analysis is effective for short duration fault

Prony analysis determines the components at actual system frequency unlike DFT which always computes at fixed nominal frequency

Algorithm to identify cause of fault will be an additional information to the system operators and maintenance crew for taking better decisions.

36

Short Duration Fault Short duration faults are defined as the faults that are cleared within two power frequency cycles.

If the faults are cleared fast, the current may not reach its faulted steady state value and the voltage may not drop to its faulted steady-state value.

37

Case Study For 2 bus system, SLG fault is simulated at 95km and 0.1s. Fault location is computed as:

Im refers to imaginary part of the quantityV is phase voltage for the faulted phase ‘x’ I is line current for the faulted phase ‘x’ I0 is the zero sequence current k0 is zero sequence compensation factor Z1 is positive sequence impedance of line

Fault Location

Observations: 1) Fault location value is dependent on fault clearing time.2) Higher the fault clearing time, more accurate is fault location value.

Fault clearing duration

Fault Location from DFT (km)

Reported Minimum Maximum Variation

1 Cycle (0.02s) 92.41 -1427.22 4358.57 5785.79

2 Cycle (0.04s) 93.61 86.05 103.44 17.39

3 Cycle (0.06s) 94.22 89.16 100.12 10.96

4 Cycle (0.08s) 94.54 91.23 98.14 6.91

5 Cycle (0.10s) 94.71 92.58 96.93 4.35

6 Cycle (0.12s) 94.81 93.45 96.19 2.74

50 Cycle (1.00s) 94.96 94.96 94.96 0.00

New Scheme

Observations: 1) Fault location is almost constant for different fault clearing time2) The value obtained are very near to expected value of 95 km

No

Any mode with frequency

variation of +/-5% from nominal

value?

Compute Fault location for the identified mode

Yes

Stop

Compute modes using Prony analysis

Consider voltage & current data for fault period and System frequency

Start Fault clearing duration Fault Location (km)

1 Cycle (0.02s) 94.862 Cycle (0.04s) 94.943 Cycle (0.06s) 94.95

50 Cycle (1.00s) 94.95

Fault Signature

Insulator failure

Tree encroachment

Fault Signature

Lightning strike

Proposed logic

Signature Correlation function Correlation function can be used to determine fault initiation time and fault

classification Pre-fault data of faulted phase can be analyzed for small excursions as

Logic to identify rise in current

Parameters Case-1 Case-2

Imax1 (kA) 4.94 8.89

Imax2 (kA) 8.61 7.67

Imax3 (kA) 8.67 6.88

Imax1 < Imax2 Satisfied Not satisfied

Imax2 < Imax3 Not checked Not satisfied

Cause of fault Tree encroachment Lightning strike

Cable protection trend

No auto-reclosure for cable fault

400 kV line protection trend

Discussions

Thank You