WAMS as Core Smart Grid Technology - Brunel University … · WAMS as Core Smart Grid Technology ... Small Signal Stability Oscillation Monitoring ... Inter-area oscillations Power

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WAMS as Core Smart Grid Technology

London12/2015

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Oleg Bagleybter, PhD

V4V1

Wide Area Measurement System -Synchrophasors

Full per-cycle detail

GPS

Timestamp

Phase

V4, V1

Magnitude

1 2 3 4

Synchrophasors: Key FeaturesSynchrophasors: Key Features

� Synchronised V, I & Frq measurements

� 50/60Hz data captures dynamics

� 3-phase measurements

� Real-time streaming

Time

Phasor

format

Phasor

format

Angle Difference increases with

• Power flow

• Impedance (weakened network)

V4V1

Voltage phase angle as an indicator of transmission capacity usage or stress

GPS

Timestamp

Phase

V4, V1

Magnitude

1 2 3 4Time

Phasor

format

Phasor

format

1 2 3 4

• Next generation measurement technology

− Voltages, currents, frequency, frequency rate-of-change, etc.

• Higher resolution scans (example: 50 samples/second)

− Improved visibility into dynamic grid conditions− Early warning detection alerts

• Precise GPS time-stamping

− Wide-area situational awareness− Faster post-event analysis

• Data integration - C37.118 Standard

Phasor Measurement Units (PMUs)

WAMS vs. SCADA

SCADASCADA

WAMSWAMS

SCADA data (@ 4 FPS)

showed a small change in

the system frequency

PMU data (@ 60FPS) showed a

much larger frequency swing

associated with the event where

frequency oscillations lasted several

seconds

Using phasors: gaining small-signal detectability

6

Source: Terna

SCADA measurementsSynchrophasors

measurements

Control Center - PDC

Copyright Alstom Grid 2013

New

Applications

Other EMS Applications

SCADA & Alarms WAMS Alarms

State Estimator State Measurement

Small Signal Stability Oscillation Monitoring

Transient & Voltage Stability Stability Monitoring & Control

Island Management Island Detection, Resync, & Blackstart

EMS

MODEL-BASED

Analysis

PhasorPointPMU MEASUREMENT-

BASED Analysis

Complementing EMS with WAMS: Earlier “Dynamic” Information for Better Decisions

The Next Generation Energy Management System!

Transitioning from traditional “steady-state” view to enhanced “dynamic” situational awareness.

Network Operational Challenges

Security

• Cascading disturbances

• System stability issues

• Security co-ordination

Constraint Relief

• Conservative margins used for dynamic constraints

• Real-time limits not known

• Interacting Controls

Sustainability

• Balancing with intermittent resources

• Impact of renewables on stability

• Smart Grid complexity

Enabling New Grid Solutions

WAMS

Generator

& ISO Compliance

Offline Analysis

Modelling

Root Cause

Analysis

Post-Event

New Smart Grid

Applications

Real-time toolsRestoration

Constraint relief

Dynamics -

early warning

Wide Area

Controls

EMS

Substation

Automation

Synchrophasor

Analytics

Distributed

Controls

State Estimation

Contingency

Analysis

Dynamic Security

Assessment

Reduce Congestion Improve Resilience System Analysis

Smart Grid Challenges

WIDE-AREA

CONTROL

Early Warnings

• Angles diverge

• Oscillation alarms

• Precursor events

Faster Restoration

• Situational awareness

• Island reconnection

• Stabilisation

• Stress reduction

What is WAMS useful for?

EVENT

PRE-EVENT POST-EVENT

Reduce Probability Reduce Impact

Control Design

• PSS/POD tuning

• GOV tuning

• Cause analysis

• Auto-action design

• OPS Procedures

LONG-TERM

Improve Performance

Real-TimeControl Room

PhasorPoint Summary

Oscillation

Management

Separation

Management

Disturbance

Monitoring

Angle

Constraints

Situational

Awareness

HistoricAnalysis & Design

Post-event

analysis

Control Design

& Test

Stability Risk

Assessment

Renewable

Connection

Operator

SupportProven Scalable Flexible

WAMS – from Small Pilot to Large Scale

Small Pilot Systems Large Enterprise-Class Systems

Supports 5,000+ phasors @ 50/60Hz

Enterprise-class reliability, security, inter-operability

Pilot installation ≤ 5 locations

Simple implementation

• High Availability & Co-Location Options

• Fully Scalable (locations, phasors, etc.)

• Fully Extensible (applications, etc.)

• Efficient & Flexible Archiving

• Flexible Display Building

• High Availability & Co-Location Options

• Fully Scalable (locations, phasors, etc.)

• Fully Extensible (applications, etc.)

• Efficient & Flexible Archiving

• Flexible Display Building

CONTROL ROOM PROCESSES

System Separation: Islanding Management

Island Detection

Algorithm (Angle & frequency

coherency)

Stabilise frequency

by balancing islands

Select reconnect

boundary

Match frequency,

voltage across

boundary

Arm CheckSync

Relay

Observe Resync

Confirm success,

close other lines

If unsuccessful,

retry with closer

frequency

Overview, Alarm �

EMS or audible

alarm

Island visualisation

Situational Awareness Operational Response

PROBLEM

IDENTIFICATION

Measurement &

Analytics

RECTIFICATION

NOTIFICATION

Feedback on

problem resolved

OPERATIONAL

WARNINGS

Alarms &

Visualisation

OPERATIONAL

GUIDANCE

Procedure to

accompany alarm

System Disturbance Management

Situational Awareness Operational Response

PROBLEM

IDENTIFICATION

Measurement &

Analytics

PROBLEM

IDENTIFICATION

Measurement &

Analytics

RECTIFICATION

NOTIFICATION

Feedback on

problem resolved

RECTIFICATION

NOTIFICATION

Feedback on

problem resolved

OPERATIONAL

WARNINGS

Alarms &

Visualisation

OPERATIONAL

WARNINGS

Alarms &

Visualisation

OPERATIONAL

GUIDANCE

Procedure to

accompany alarm

OPERATIONAL

GUIDANCE

Procedure to

accompany alarm

Detect disturbance

Locate trigger point

Detect event type

(load/gen/line loss)

Estimate impact

Num. events & impact justify

action

(re-dispatch or load shed)

Locate effective action

Decide level of action

Confirm freq restored

Identify any grid

bottleneck

Check oscillations

Display trigger location

Show sequence

(multi events � high risk)

Log impact

Oscillatory Stability Monitoring

Oscillation

Indicator

Since 1999

• 0.5Hz Mode Poor Damping

− Reduce Scotland-England Flow

• Other Mode Instability

− Broadcast alert to generators, affected units reduce output

Situational Awareness Operational Response

PROBLEM

IDENTIFICATION

Measurement &

Analytics

PROBLEM

IDENTIFICATION

Measurement &

Analytics

RECTIFICATION

NOTIFICATION

Feedback on

problem resolved

RECTIFICATION

NOTIFICATION

Feedback on

problem resolved

OPERATIONAL

WARNINGS

Alarms &

Visualisation

OPERATIONAL

WARNINGS

Alarms &

Visualisation

OPERATIONAL

GUIDANCE

Procedure to

accompany alarm

OPERATIONAL

GUIDANCE

Procedure to

accompany alarm

Oscillatory Stability Monitoring: Problem Identification

PROBLEM

IDENTIFICATION

Measurement &

Analytics

PROBLEM

IDENTIFICATION

Measurement &

Analytics

1/F MODE FREQUENCY

MODE AMPLITUDE

A

MODE DECAY TIME

EXP(-t/ ???? )

MODE PHASE

Mode Frequency

Mode Amplitude

Mode decay time

Mode Phase

Exp(-t/τ)

Measured P / f / δ

Simultaneous multi-oscillation detection and

characterisation direct from measurements

(no modelling required)

Fast Modal

Analysis:

Alarms

Trend Modal

Analysis:

Analysis

Oscillations

0.005-0.1Hz Governor / frequency

0.1-4.0Hz Electromechanical

0.1 – 1Hz Inter-area

1 – 2Hz Local

2 – 3Hz Interplant

4.0-45Hz Sub-synchronous

Early warning of poor damping

Source Location of contributions

Guidance for real-time & planning

CASE STUDIES

National Grid UK & AEMO Australia

Constraint Relief

Australia3 Oscillation Constraints

Great BritainScotland – England

Interconnector

Transmission Corridor Net Transfer Capacity

+128MW

Model limit

with margin

Limit with

measured

damping

Thermal limitAREA 1

AREA 2

+160MW+200MW

Damping Measurement for Real-Time Constraints

• Modelling uncertainty requires large margin

• Use margin as long as observed damping is good

• Reduce transfer if poor inter-area mode damping occurs

AEMO, Australia

Security

• 150MW Oscillations, high risk of separation leading to blackout

• Alarm flood in EMS

• PhasorPoint shows damping issue begins with generator start

• Operators able to take action to avoid separation

• Root cause was generator control fault

• Similar instability 2010; other cases avoided by early warning

ACAM ProjectAngle Constraint based Active network Management

ACAM Principle:• Measure angle difference

between wind generators

and key grid sites

• Network studies � max

angle between PMUs for

all load / generation and

outage scenarios

• Angle acts as proxy for

thermal, reverse power

flow & voltage excursions

• Control algorithms to

curtail generation based

on angles

ACAM ProjectAngle Constraint based Active network Management

ACAM Pilot Network:

• 33kV network on Anglesey

• High wind penetration,

>33MVA connected

• Several connection requests

for wind, hydro & large PV

• Voltage, thermal & reverse

power constraints limit BaU

connections

• ACAM minimises the

monitoring & comms

channels required

• Adaptable to network

changes

HVDC

Sub-Synchronous Oscillation (SSO) Monitoring - Ongoing

Sub-Synchronous OscillationsCapacitors in series with inductance � natural frequency.

Natural frequency coinciding with torsional or control mode � resonanceCan involve series caps, thermal generators, windfarms, HVDC

Novel Analysis & Early Warning

Determine effective LC natural frequency (no resonance) � understand

variabilityReal-time detect near-resonance � raised amplitude, modes interacting

� Address by changing effective L (by dispatch) AVOID TRIPPING

SSO Outstation and Applications

New 200Hz waveform streaming from integrated DFR/PMU/SSO

Outstation4-45Hz Frequency, amplitude, damping analysis

<80Hz Spectrum (2nd phase)

RA33x

Acquisition Unit

RPV311

Central Unit

Installed & Operational by Fixed

Series Capacitor Installation March

2015

Series Capacitors

Thermal GeneratorsWindfarms

Sub-Synchronous Resonance - Ongoing

Torsional frequencies fixed

Effective L varies with

system condition

Series capacitance may

be fixed or controlled

� Some uncertainty in

SSR behaviour

SSR Typically ~10-40Hz

Derive SSR components from Waveforms (not phasors);

WAMS infrastructure for Control Room Alerts & Analysis

Transient stability limits based on ANGLE information

δ

(δ)

δP

B6 (Cheviot) Boundary

~ 3.5GW Transient Stability Limit (P)

~ 1.5GW Wind Capacity in Corridor

���� Volatility in corridor capability

Expressing Limit as Angle

• Transient stability closely related

to angle difference

• Define limits by Angle, not MW

alone

• Possible future use of angle in

new HVDC control

Energinet, Short Circuit Capacity

• Alert and Alarm on low SCC due to HVDC issues

• Action taken to increase SCC if in Alert state

• HVDC protected in case of low SCC

• Future work in relating system conditions to SCC

• Flexible SCC trending

Security Constraint Relief

Short Circuit Capacity from PMUs

Concept

• Calculate RoC of V&I due to “downstream” event (not changing source V & Z)

• Filter switching events are downstream. SCADA switching event sent to PhasorPoint to initiate SCC calculation.

ZI

V=

∆

∆−

&

&

Benefits

• Ensure SCC large enough at connection to HVDC

• Address uncertainties in model based SCC with high renewable generation

• Relax generation dispatch constraints

• Filter switching can be initiated manually when SCC value needed

• Historical SCC for planning

Landsnet, Iceland Control Centre

Overview Islanding

Selected Freq, Voltage,

Boundary & Key Unit P Islanding

Selected Freq, Voltage,

Boundary & Key Unit P

PhasorPoint used in operational procedures for:

Islanding & ResynchronisationResolving instability in disturbances

Dynamics Issues in Iceland

Problem Solutions

Inter-area oscillations Power System Stabilisers (PSS)

Wide Area PSS

SVC Power Oscillation Damper

Very low frequency oscillations Governor tuning

Angle stability Wide Area Defence

Controlled Separation

Island stability Secure transitions

Reduce exposure time

Governor control

Landsnet Control Project

Gen Fast Ramp

Fast trigger

Smelter 1 Control

Down&Up - fast

action Smelter 2 Ramp

Down action

Wide Area POD

Adaptive damping

East Load Shed

Triggered load

shedMicrogrid

Island operation

Adaptive Islanding

Choosing split-line

KRA Gov Mode

Enable speed modeTrial Active NowInitial scheme operational

Planned1-4 year timeframe

Deploy PSS parameters

• Dynamic performance review

− After ~ 2-4 weeks

• Acceptance or review

− Performance improvement− No increased risks

• Before PSS tuning

• After PSS tuning2.0Hz Mode

Mode Decay Time Constant (sec)

Mode Amplitude (MW)

• Before PSS tuning

• After PSS tuning1.2Hz Mode

Mode Decay Time Constant (sec)

Mode Amplitude (MW)

• Before PSS tuning

• After PSS tuning0.8Hz Mode

Mode Decay Time Constant (sec)

Mode Amplitude (MW)

National Grid Frequency Control NIC

• National Grid projects Frequency Reserve Cost increase £60M now � £250M by 2024 due to reduced inertia

• Wind, storage, PV, DSR etc. can provide useful non-conventional Frequency Response

• Enhanced Frequency Control Capability (EFCC) accelerates response and co-ordinates diverse resources

• Target reserve response deployed 0.5-2s(at present 2-10s)

• Facilitates a Frequency Response Aggregation Service for diverse resources, thus an enabler for a Fast Frequency Response Market

Target (Alstom):Develop new monitoring and control system (MCS) and

demonstrate viability of obtaining rapid frequency

response from new resources (including renewables and

demand side response)

Reducing Inertia with Increasing Share of Wind

• Large high wind N�S power flow

• Major constraint Scotland-England

• Inertia reducing, esp in Scotland

− Wind power - no inertia− Interconnectors – no inertia− Synchronous plant closed or constrained off

Large Wind

Resources

Largest

Load

Inter-

connectors

Wide-Area Control

Measured Frequency response to generator loss

RoCoF varies across system depending on event proximity

• Wide-area observability required for this behaviour

• Use of Angles information

• Used to prioritise action closer to event

• No visualisation can lead to separation

System Splits

Risk of blind control

GE WAMS Centre of Excellence – Edinburgh(former Psymetrix)

Advanced Phasor

Framework

• Data Management

• Analysis Tools

• Visualisation

Advanced Phasor

Framework

• Data Management

• Analysis Tools

• Visualisation

Phasor Applications

• Reliability

• Constraint Relief

• Dynamic Performance

• Renewables Integration

• Wide-Area Control &

Protection

Phasor Applications

• Reliability

• Constraint Relief

• Dynamic Performance

• Renewables Integration

• Wide-Area Control &

Protection

Consulting Services

• WAMS Deployment

• Dynamics & Control

• Operations & Planning

Guidance

• Power System Analysis

Consulting Services

• WAMS Deployment

• Dynamics & Control

• Operations & Planning

Guidance

• Power System Analysis