deregulated electricity markets. the role of the iso. processes and systems
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The role of the ISO in deregulated energy marketsEnergy Trading & Risk Management Systems Group @ linkedin
The role of the ISO in deregulated energy marketsEnergy Trading & Risk Management Systems Group @ linkedin
This ppt represents the first delivery of a collection of presentations that will bedelivered by the Energy Trading & Risk Management Systems Group members @tlinkedinlinkedin.
Would you wish to participate (extending the current presentation, delivering apresentation, providing with feedback) do not hesitate to contact with any of theETRM Group managers.
Any Energy Trading & Risk Management Systems Group member is kindly invited todisclose the ETRM Systems Group source when using partially or totally thispresentation.
The role of the ISO in deregulated energy marketsVersion I. January 2012.
ISO
MORegulatory
Electricity markets
Deregulated
MOg ybodyThe only possible way to fully
understand an integrated ETRMframework is understanding allthe complexities around electricity
marketsGENCOEligible
customer
the complexities around.
Would it be possible tod d h GENCO
DISCOSupplier
understand how a GENCOoperates without understandinghow ISO’s operate ?
The Energy Trading & Risk Management Systems Group has an initiative focused todeliver an integrated vision of ETRM systems including understanding the processesdeliver an integrated vision of ETRM systems, including understanding the processesinvolved in power, gas, oil …
ISO –Independent System OperatorR li bili id i i i i d i d d d di i i i
G id l i
Reliability considering economic criteria under independence and non discriminationbasis
Grid planning
Outage management
Load TSO
Demand response
forecastingTSO
coordination
Reliability
ISO
MeteringVoltage control IndependenceEfficiency
SettlementFrequency control
Non discriminationUnbundlling
BillingCongestion pricing
discriminationg
Informationmanagement
Black start market
Ancillary Services
ISO –Independent System Operatorp y pCentralized versus non centralized approaches
In a pure decentralized scheme, the market agents agree on deliveries by means of bilateral contracts at aprice fixed by them. The ISO must accept those arrangements unless they are technically unfeasible. The ISOruns ancillary services, purchasing the service at a “market price” offered by the market agents. Participation ofancillary services is not mandatory.
The market agents might trade also in a Power Exchange in which bids and offers are matched by means of anauctioning process. This is a blind market, and some level of “centralized optimization” is incorporated in thesense that only the most economical offers are matched. In some places participation in this market ismandatory, while in others it is not. Nevertheless, market players still can define the price at which they wantto bid, so they can effectively “uncouple” generation costs with the bidding stacks, that are based on, y y p g g ,maximization of generator’s benefits. There is not possibility to make a final (global) generation schedule basedon real generation costs. This is still a decentralized scheme
In an hybrid model, the generators might arrange bilateral contracts and match bids in auctioning processes iny , g g g g p“blind” power exchange markets (decentralized approaches), but the spare available energy must be offered toancillary services under a mandatory framework (centralized approach). Generation schedules will be arrangedby the ISO under a cost‐based approach based on optimal power flow analysis (this is, the generator does notsend “bids”, but generation “costs”). Ancillary services might be paid at a “Local Marginal Price”.
In a pure centralized model, the generators just send costs associated to generator. The ISO arranges schedulesbased on the optimization of the global generation. Generators are rewarded at their generation cost, althougha prime can be added to the costs. This is a case of regulated environments.
ISO –Independent System Operatorp y pEfficiency …. A long way to go ….
An “efficient scheme” should produce appropriateeconomical signals for efficient investing in transmissionresources and in efficient location of new generation andloads.
Zonal aggregation
Nodal
of efficiency
Ideally, the framework should be simple to implementand transparent .
ISO’s grid planning responsibilities should be enforced to
Zonal
L l f l it
Level o
g p g pgain efficiency (centralized model) or to assure a certainlevel of sustainability (decentralized model).
Level of complexityCentralized approaches enable nodal pricing under acost based approach
Rules and regulation should be carefully designed in order to avoid collusion of prices and to discourage inefficientallocation of generation assets and loads. Apparently, deregulation of markets and implementation of decentralizedframeworks have led to importing from other kind of industries of “pure market models” , which have proven not towork appropiately in the electricity sector. Social welfare demands a re‐definition of deregulated electricitymodels !
Albert Einstein: everything should be made as simple as possible, but not simpler
models !Clear governance mechanisms for the ISO are fundamental for a proper functioning of the deregulated framework.
y g p p p
ISO –Independent System Operatorp y pThe figure of the MO
In decentralized models, the idea is to enable an independent marketplace in which the market agents can tradeenergy by means of bilateral contracts or auctioning processes in a “power pool”. The market agents look for “benefitmaximization”. As long as those matched bids between buyers are purchasers comply with technical restrictions, theISO is obliged to schedule those programs, even if they do not comply with minimum cost criteria of power networkg p g , y p y pexploitation. In this framework, in order to “isolate” as much as possible the power exchange from the powernetwork exploitation, the “Market Operator” – MO figure is created in some markets.
Constrained schedule
Unconstrained schedule
MOISO
Basically, when the MO exists, this entity will be in charge of financial markets (futures, forwards ... ), day ahead andeven intradaily markets (but always will need to coordinate with ISO to assure technical feasibility of the schedules). Inother market models, it will be the ISO the one in charge of all markets and only financial markets that don’t implyph sical deli er might be r n b a different entit (an e change)physical deliver might be run by a different entity (an exchange).
Hereinafter, unless otherwise stated, we will understand that we are facing a decentralized market. In the future, apresentation regarding the MO will be delivered and more details of power exchanges will be provided .
More detail on Market operators and Power Exchanges will be delivered in further presentations.
ISO –Independent System Operatorp y pVery high level voltage power network exploitation under reliability and economic criteria
Independent System Operator is an entity that coordinates, controls and monitors the operation of the electricalpower system in a reliable manner and following economic dispatching criteria.
The ISO coordinates the operation of the transport network in coordination with the transmission system operators.Its main objective is to maintain the system frequency (eg. US, 60 Hz; Europe, 50 Hz).
Depending on the market model, the ISO might have more or less power to control investment decissions of TSO,generators .... From the writer's opinion, grid planning should strongly rely on ISO’s recommendations, regardingreliability and power network efficiency.
Frequency controlV lt t lVoltage controlLoad flow controlOutage managementEconomic dispatching
ISO –Independent System Operatorp y pSCADA – Supervisory Control and Data Acquisition architecture
Independent System Operator is an entity that coordinates, controls and monitors the operation of the electricalpower system in a reliable manner and following economic dispatching criteria.
• RTU• IED
SCADA Server
• Lines• Transformers• Generationunits
• Shuntcapacitors,reactors
Network Topology
• Measure• Transmissionlosses
• Status
State Estimator
Load flow and voltage control
Monitoring and control is done byreactors…means of the SCADA system.
RTU Remote Terminal UnitIED Intelligent Electronic Device
Load flow and voltage control can be controlled by generation allocation, change in network topology, change oftransformer taps, use of reactors and shunt capacitors. Generators can also contribute injecting or absorbingreactive power. Advanced power flow control is an enormous field to be fostered.
Frequency control
The way to maintain system frequency is essentially matching at every moment power generation with system loady y q y y g y p g y(including power network losses). Different markets (usually based on auctioning processes) are held in order tomatch from the day ahead to as close as real time generation with load.
ISO –Independent System Operatorp y pSCADA – State estimation
State estimation
A process run in real time on SCADA systems in order to correct raw data and measurements coming from the fielddevices (RTU’s …) which filter measurement noise, detect gross errors and provides as an output estimatedi f i f d b d h il bl i f i d h k d l dinformation of system state and measures, based on the available information and on the power network modeledwithin the SCADA system.
State i bl
Topology processor
State variables: bus voltages, branch flows (MW, MVaR), …coming from field devices through RTUs, IEDs…
Processing
variables
Topology processor: gathers status of circuit breakers, switches,and represents the system topology.
ProcessingFiltering: identifies and eliminates incorrect data comingfrom fieldProcessing: estimates network status (open/closed ‐ circuitbreakers, shunt capacitors, reactors) and state variables (voltage, phase angles, transformer taps…)
Status Measures
ISO –Independent System Operatorp y pRepresentation of processes previous to day D
year ahead Months ahead
MO rket
year ahead Months ahead
MSO TF ac
ity R
ights
mar
annin
g
O’s) TLF
utage
ana
lysis
outag
e an
alysis
ssIS LT
ansm
ission
Cap
a
Grid
Pl
d dev
elopm
ent (
GENC
O
sed d
evelo
pmen
t
r TCR
MT
Gene
ratio
n ou
Tran
smiss
ion o
netw
ork
outag
e gen
erati
on un
its(G
ENCO
s)
e sch
edule
utage
gene
ratio
n unit
s(G
ENCO
s)
ssign
ment
Agen
tsO
Tra
ed de
velop
ments
Plan
ned
orise
d dev
elopm
ents
Autho
ris
Bids
for
ed ou
tage t
rans
miss
ion
Plan
ned o
miss
ion ne
twor
k outa
ge
Plan
ned o
TCR
as
The ISO interfaces with TRANSCOs Suppliers GENCOs and with the market operator (MO) in charge of Day Ahead
TRAN
SCO
Plan
n
Autho
Plan
n
Tran
s
The ISO interfaces with TRANSCOs, Suppliers, GENCOs and with the market operator (MO), in charge of Day AheadMarkets – DAM – and even intradaily markets). In many market models, the ISO is in charge of all markets, includingDAM, intradaily and ancillary services markets. In others, the MO handles day ahead markets.
ISO –Independent System Operatorp y pRepresentation of processes previous to day D
sMonths ahead Day ahead
MO
DAM
dule le ntr
aday
mar
kets
dule
ule
Months ahead Day ahead
MSO Un
cons
traine
d sch
ed
Cons
traine
d sch
edul
day m
arke
ts
(N) I
Unco
nstra
ined s
ched
y ana
lysis
Cons
traine
d sch
edu
marke
t
TLF
y ana
lysis
marke
t
sIS
Bid f
or D
AM
nstra
ined s
ched
ule
Bid
s for
per
iodic
Intra
d
Feas
ibility
strain
ed sc
hedu
leTCR
m ST
for T
CR
assig
nmen
ts Feas
ibility
al co
ntrac
ts
TCR
m
for T
CR
assig
nmen
ts
y righ
ts no
mina
tion
Agen
tsur
B
Unco
n
Unco
nsBid
TCR
a
Bilat
era
Bid
TCR
a
Capa
city
The ISO interfaces also with neighbour ISOs . Even in single zonal models a Transmission Capacity Market to manageneig
hbou
ISO
g g p y gtransmission capacity rights (TCR) between neighbouring networks must be defined. Usually there is an annualauctioning process between ISO and interested parties and also secondary markets can exists, in order to manageefficiently the TCR as real time market approaches.
ISO –Independent System Operatorp y pLong term load forecast as part of ISO processes
Projected
Historical Economic factors
Economic factors Demographic
data
MeteredLoad data
Time factors
Forecasting model
Historical weather data
Calendar datamodelweather data data
Winter peak LTF Summer peak LTFWinter peak LTF, Summer peak LTF
A long term forecasting (LTF) model is fundamental in order to understand which will be the peak and winter loadsA long term forecasting (LTF) model is fundamental in order to understand which will be the peak and winter loadsthat the power system will need to support. This will be an input for the grid planning function.
ISO –Independent System Operatorp y pGrid planning as part of ISO processes
Proposed M k A
Desired quality
Regulatory framework
Market Agent projects Technological
factors
Power flow simulation
Transmission network (TN)
existing
metrics simulation
Stability analysis
Grid LTF
constraints
Short circuit lplanning
LTF analysis
Authoritasion / Denial / propositionAuthoritasion / Denial / proposition
Grid planning under a centralized approach is fundamental to derive in market efficiency. The ISO must be enacted toauthorise, deny or propose long term power network development actions (including generation, transmission andload allocation if possible) so that the grid is developed under a sustainable and efficient criteria.
ISO –Independent System Operatorp y pMiddle term load forecast as part of ISO processes
Projected E iHistorical
Economic factors
Economic factors Forward
prices
MeteredLoad data
Time factors
Forecasting model
Historical weather Calendar
datamodeldata data
Medium term load forecastMedium term load forecast
A middle term load forecast for months ahead to even 1 year ahead is calculated. The objective is mainly outagemanagement. The forecasting algorithms used differ from those used for short term forecast (days ahead) and neartime forecasts (close to real time) and of course LTF.
ISO –Independent System Operatorp y pOutage analysis in order to guarantee power network reliability
MTLF
•Medi
Load
MTLF
um Term
forecast
•Lines •Transformers•Generation units•Shunt capacitors,
Network topology
•Generation•Load
Peak scenario
•Lines•Generation units•Transformers
Contingency analysis
reactors, …
Outage schedule
The ISO models on the stable network topology a base scenario for peak loads (based on output from the middleterm load forecasting solution) The study can be executed either in the SCADA system (study mode) or in an
Outage schedule
term load forecasting solution). The study can be executed either in the SCADA system (study mode) or in anindependent (not part of SCADA) power system simulator. N‐1 scenarios are modeled (e.g simulating the outage of apower line, a transformer, etc) under the contingency analysis. Only planned outages that derive in acceptable results(in terms of load flows and voltage levels) are approved.
ISO –Independent System Operatorp y pShort term load forecast as part of ISO EMS system
Metered SCADA
Weather forecast
Load dataSCADA actuals
Prices
Weather actual
Time factors
Forecasting model
Historical weather Calendar
datamodeldata data
Short term load forecastShort term load forecast
A short term load forecast for 1D to even 1 week ahead is calculated and published by ISO. The frequency ofcalculation might be hourly and the granularity of forecasts usually hourly Different methodologies can be deployedcalculation might be hourly and the granularity of forecasts, usually hourly. Different methodologies can be deployed; most common are neural networks and statistical methods. Load forecast is published through the web to allinterested parties, so they can prepare bid stacks accordingly. The objective is to maintain system reliability.
ISO –Independent System Operatorp y pDifferent markets – from day ahead to real time operation
Day time of each marketPeriod ahead on which each market appliespp
1 2 3 4 5 6 7 8 9 10 11 13 14 16 17 18 19 21 22 23 1 2 3 5 6 8 9 10 12 13 14 16 17 18 19 20 21 22 23 24
Day D-1 Day D4 7 11 1512 15 20 24
Day -ahead marketIntraday 1
Compañía Operadoradel Mercado
Intraday 1Intraday 2
Intraday 3
Intraday 4Intraday 5
Intraday 6RED ELÉCTRICARED ELÉCTRICADE ESPAÑA
Technical constraints
Secondary Regul .Imbalances .
Imbalances .
Tertiary Regulation
T. constraints in real time
Imbalances .Imbalances .
Imbalances .
1 2 3 4 5 6 7 8 9 10 11 13 14 16 17 18 19 21 22 23 1 2 3 5 6 8 9 10 12 13 14 16 17 18 19 20 21 22 23 2412 15 20 24 4 7 11 15
A representation of the different markets held in Spain by the ISO. Day ahead markets and intraday markets are heldby the Market Operator (Power Exchange or Power Pool) in coordination with the ISO
Source: REE
by the Market Operator (Power Exchange or Power Pool) in coordination with the ISO.
ISO –Independent System Operatorp y pAnalysis of unconstrained programs
STLFUnconstrained
schedule( )
•Short TermLoad forecast
•Unconstra
schedule•G
eneratiostacks
(MO)
m
ained
n bid
• Lines • Transformers • Lines• Generation units
• Shunt capacitors, reactors, …
Network topology
• Generation• LoadLoad flow
• Lines• Generation units
• Transformers
N‐1 cases • Load flows• Voltage levelsOPF
Optimal constrained program
All the parties make bids in order to maximize benefits. The (unconstrained) schedule that has been matched by the MOaccording to economic criteria (and even considering some technical characteristics of the generation units ‐ e.g. ramps) isanalyzed in conjunction with the bilateral contracts information under a load flow simulation and even stressed to N‐1 cases.After the scheduled program has been validated for technical conditions, a “constrained” schedule is generated and sent to theMO. The ISO only analyses the technical feasibility of the schedules, but does not run an OPF * to look for a minimum costsolution for the power network (in the sense that the matching algorithm results of the MO is respected as long as it compliessolution for the power network (in the sense that the matching algorithm results of the MO is respected as long as it complieswith technical restrictions) * clarification: conditional on the market agents bids, the solution obtained is optimal; it might beconsidered a constrained case of an OPF in which the ISO can determine each unit commitment based on a cost function, as in aregulated environment – pure centralized model – complete OPF, as we can see in next slide. All generation units are paid at theMCP (Marginal Clearing Price) for each of the time intervals in which it has been calculated.
ISO –Independent System Operatorp y pComparison of approaches ‐‐ How would it be under a pure centralized approach
STLFGeneration
•Short Termforecast (b
•Planned out•Fixed costs•Variable co s m
Load bus level)
tages
sts
• Lines • Transformers• Generation units
• Shunt capacitors, reactors, …
Network topology
• Generation• LoadLoad flow
• Lines• Generation units
• Transformers
N‐1 cases • Load flows• Voltage levelsOPF
Optimal constrained program
Under a centralized approach the ISO would consider generation costs of all available generation units. According to minimumcost criteria, the ISO would find, running an optimal power flow, the minimum cost generation schedule. The generators wouldhave to assume the mandatory generation schedules imposed by the ISO. Each generation unit would be paid at its node pricel l If titi t b f t d l l i l i ld b id i t d N t th t d d t li d hlevel. If competition was to be fostered, local marginal prices would be paid instead. Note that under a decentralized approachthe ISO will not run an OPF considering cost prices of generation units; instead self committed prices fixed by the generatorswould be used. That is why we insist in clarifying that in a decentralized model, an “optimal” solution can be found butconditional on prices fixed by generators. In that sense, the solution obtained in an centralized model derives in a more efficientprogram, as it is not subject to gaming by market agents.
ISO –Independent System Operatorp y pOPF ‐ Optimal power flow
Optimal power flow
Once a state estimation has been run – real time dispatching (or a base case has been defined ‐ planning), an OPF canbe run. The OPF solves the power flow equations using control variables to achieve an objective function, as forexample to mimimise the cost of generation by means of control variables with upper and lower limits. In acentralized approach generation costs are considered and in a decentralized model generation bid stacks arecentralized approach generation costs are considered and in a decentralized model, generation bid stacks areconsidered.
b l
Network topology
Objective function
Control variables
State variables
OPFState
topologyconstraints
Control OPFState estimation variables
constraints
Control variables parameterization
ISO –Independent System Operatorp y pGeneration of unconstrained programs (in many market models this is done by the MO)
MCP Auction processDemand (Purchase)
Supply (sale)
MCVMCV
Unconstrained schedule
Usually in an auction – based process a MCP (Market Clearing Price) and a MCV (Market Clearing Volume) is obtainedfor each of the 24 hours of the day ahead market The algorithm specifications and the granularity of the calculations
Unconstrained schedule
for each of the 24 hours of the day ahead market. The algorithm specifications and the granularity of the calculationsare specific of each marketplace. The algorithm might be single zone or multi‐zonal based, include complexconditions from generators , etc. The unconstrained schedule will need to be further validated under an technicalpoint by the ISO.
ISO –Independent System Operatorp y pGeneration of constrained programs for DAM and intradaily markets
STLFU t i d h d l (MO)
Base case
STLFUnconstrained schedule (MO)
Optimal power flow Contingency (N‐1 ) analysis
Produce constrained schedule
Reliable?no
Publish
yesGENCO’s bid stacks
In case the unconstrained schedule does not derive in a reliable network exploitation solution, a feasible solution issearched until it complies with the AC network analysis. In some cases the AC OPF problem is approximated by DC‐OPF problems.
ISO –Independent System Operatorp y pRepresentation of processes (cont)
stionDay ahead
s on AGCIntraday
O
SO alanc
es m
arke
ts
ary f
req.
regu
lat
asibi
lity an
alysis
NTLF
alanc
es m
arke
ts
sibilit
y ana
lysis
ry fre
q. re
gulat
io
asibi
lity an
alysis
ncy r
egula
tion A
oltag
e con
trol
verlo
ad co
ntrol
nal e
xcha
nge
sche
dule
l dinati
on w
ith T
SO
asibi
lity an
alysis
I
imba
lance
s mar
ketIm
ba
ec. fr
eque
ncy m
arke
tSe
cond
Sche
dule
Fea
mbala
nces
mar
ketIm
ba
Sche
dule
Fea
ertia
ry fre
q. ma
rketTertia
r
Sche
dule
Fea
Freq
uen
GC si
gnal
Vo OvZon
Sche
dulef
or in
ter-zo
naex
chan
ge Coor
d
Sche
dule
Fea
GENC
Os Bid f
or
Bid f
or s
Bid f
or im
Bid f
or te AG
ighb
our
ISO
al ex
chan
gesc
hedu
le
A representation of the different markets held in Spain by the ISO. Day ahead markets and intraday markets are held
Nei
Zon s
by the Market Operator (Power Exchange or Power Pool) in coordination with the ISO.
ISO –Independent System Operatorp y pNear term load forecast as part of ISO EMS system
Metered SCADA
Weather forecast
Load dataSCADA actuals
Prices
Weather actual
Time factors
Forecasting model
Historical weather Calendar
datamodeldata data
Near term load forecastNear term load forecast
A near term load forecast for minutes / hours ahead is calculated by ISO EMS. The frequency of calculation might beeven 5 minutes and the granularity of forecasts might be 5 minutes as well The objective is to compare NTLF witheven 5 minutes and the granularity of forecasts, might be 5 minutes as well. The objective is to compare NTLF withthe STLF. Imbalance markets are called regularly during the day in order to cover those differences, and to keepsecondary regulation reserve.
ISO –Independent System Operatorp y pEconomic dispatching ‐ Ancillary services
Imbalances marketsIn order to manage imbalances that have not been covered by intraday markets, either because of change in the STLFor because of generation plants unavailabilities.
Secondary reserve marketIn order to cover the requirements of secondary reserve for the day ahead.
Secondary reserve is a spinning reserve which objective is to support the primary reserve (frequency control) and toy p g j pp p y ( q y )solve imbalances. It can be activated in very short periods (e.g available in 30 seconds – 15 minutes)
Tertiary reserve marketd l d i i iIn order to replace secondary reserve in case it is necessary.
Tertiary reserve is power capacity which can be connected under tertiary control, in order to provide an adequatesecondary control reserve. It can be activated in periods between 15 minutes – 30 minutes.
Frequency regulation by the AGCThe AGC (Automatic Generation Control) is an automatic adjustment signal sent to all AGC‐regulated generation unitsin order to compensate for ACE (Area Control Error ‐ Instantaneous difference between scheduled generation andactual load within a control area It is calculated as a frequency control mechanism in about 4‐10 seconds intervals byactual load, within a control area. It is calculated as a frequency control mechanism in about 4‐10 seconds intervals bycomputers in the dispatching center).
ISO –Independent System Operatorp y pGeneration of programs for Ancillary Services
Schedules STLF NTLFState estimator
Ancillary Service Request
Schedules STLF NTLFState estimator
Ancillary services bidsMatching algorithm
Produce constrained schedule
Optimal power flowContingency analysis
Network topology
State estimator
Reliable?
yes
no Schedules
According to existing schedules, actual measures (state estimator), and the results of the STLF / NTLF, the capacity for
Publish
According to existing schedules, actual measures (state estimator), and the results of the STLF / NTLF, the capacity forancillary service is requested in order to cover forecasted imbalances. If secondary reserve has be used, tertiaryreserve is proportionately transferred to secondary reserve and more tertiary reserve is requested.
ISO –Independent System Operatorp y pReal time frequency control
Primary frequency reserveGeneration reserve which objective is to maintain a control area frequency and that can be activated immediately (5– 30 seconds) in a direction that stabilizes frequency. Turbine governors are the main source of frequency response. Itinvolves autonomous and automatic actions to arrest deviations in power system frequency whenever imbalancesp y q yarise between load and generation.
All generation units participate in primary control (mandatory). The settings on the governors are set locally, and theISO has not control on them (in the sense that they are not governed by AGC).
Primary reserve Secondary reserve Tertiary reservePrimary reserve
Local
Secondary reserve
AGC governed
l h d h h
Tertiary reserve
Replaces secondary reserve
l h d h hMandatory
Response‐ 5 – 30 secs
Only generation units with AGC and whichhave offered regulation services in secondaryreserve market.
Response 30 secs‐ 15 min
Only generation units with AGC and whichhave offered regulation services in tertiaryreserve market.
Response from 15 min …
ISO –Independent System Operatorp y pSecondary frequency control by AGC ‐ ISO dispatching center – EMS system
Actual generation
(state estimator)
Scheduled interchange
Frequency Actual interchange
AGCSecurity
constrained economic
GENCO’s AGC StatusAGCeco o c
dispatchS a us
AGC base points
The AGC scheme can be centralised or decentralised . In a centralised scheme a control area is assigned to a GENCO.Therefore each control area might be composed of many generation units regulated under the same master AGCTherefore, each control area might be composed of many generation units regulated under the same master AGCsignal. The master (ISO) AGC signal is sent to the different control area AGC, instead to each generation unit. In thisscheme, a GENCO can distribute the control area AGC regulation band between the different generation units.
ISO –Independent System Operatorp y pPower network control (real time) – voltage and overload control
RTU
•States•M
easure
RTU
• Lines
Voltage control at bus level
Voltage control
ements
• Lines • Transformers• Generation units
• Shunt capacitors, reactors, …
Network topology
• Generation• Transformer loads
• Flows
Stata Estimation
Analysis of load flows at power
line & transformer level
Overload control
• Generation• Transformers taps
• Capacitor shunts
• Reactors
OPF
transformer level
Change network topology
In case the unconstrained schedule does not derive in a reliable network exploitation solution, a feasible solution issearched until it complies with the AC network analysis.
Voltage and load flows are monitored constantly. An alarm is displayed in the SCADA system whenever voltages orload flows violate predetermined ranges. Tap transformers, reactors, shunt capacitor, generation units, can be usedto control voltage and even to adjust load flows (changing the network impedances by moving transformer taps atcertain network nodes).If that is not enough, then it might be necessary to reassign generation schedules to change load flows, by means ofancillary services markets. A reactive power market can be applied as ancillary service.
ISO –Independent System Operatorp y pRepresentation of processes (cont)
D+ N ion
SO Invoic
ing
Settle
ment
read
ing ac
quisi
ti
I
Reso
lution
Meter
r•Instantaneous MW•Instantaneous MVaR
SCADARTU
SCADA database∫
∫dtMVaR
dtMW
.
.
s pute
uisitio
n
ment
•MWh•MVaRMetering
devices Metering database
GENC
Os Disp
ter re
ading
acqu
stima
ted se
ttlem
Once the ISO (or a third party) has collected metering information from the metering devices (notice this is adifferent source than the information that was coming to the SCADA system in real time) the settlement is done to
MetEs
different source than the information that was coming to the SCADA system in real time) the settlement is done toGENCOs. The GENCO’s on the other hand have integrated metering information form their SCADA system, as well asmetering information from metering devices.After any dispute has been solved, the final settlement is conducted and invoicing takes place.
ISO –Independent System Operatorp y pThe role of the ISO in the smart grid development
h l d d l h f ll l f h kThe evolution towards a smart grid is clear. This for sure will require an evolution of the transmission power network,ISO’s workflows, processes and systems, in order to cope with marketplace demands. Some of the fields that willevolute in the future years are:
Advanced power flow control
HV Electronic power equipment (e.g bulk storage),FACTS (Flexible Alternating Current TransmissionSystems) D‐FACTS devices, CLD (current‐limiteddevices), etc
Advanced protectionSynchronised phasor measurements, computerrelay, advanced load shedding or even zonesplitting schemes.
Advanced network monitoring
Introduction of PMU’s (Phasor MeasurementUnits), improving state estimates, post‐disturbanceanalysis and generally speaking, control.g
Advanced economic di t hi h
AMR (Advanced Metering Reading devices) will leadtowards DR (demand response) frameworks that willrequire an evolution of the economic dispatchingdispatching schemes require an evolution of the economic dispatchingschemes, including load forecasting.
ISO –Independent System Operatorp y pArchitecture
Corporate enterprise networkSecondary Control center
SCADA servers
SCADA Communication
servers
Datawarehouse
Settlementservers
Dispatcher consoles
Primary Control centerFinance Web
servers….
Secondary Control center
LAN
WAN
SCADA HistorianData server
Economicdispatch
Data server
Meteringsystemserver
Meteringcommunication
servers
Load forecastservers
External users
A simplified view of an ISO architecture. Duplicated sites with hot redundancy at each of the sites is absolutelynecessary to guarantee reliability.
Energy Trading & Risk Management Systems Group @ linkedingy g g y pA long road ahead
You are kindly invited to join ETRM Systems Group at linkedin, and to share with thegroup members presentations, papers, works related with ETRM systems andenvironments.
Want to collaborate with the ETRM Group? please contact with ETRM Groupmanagers
Leena Dsouza ldsouza4210@hotmail.comMack Frankfurter mack.frankfurter@iq3group.comEnrique Rivero eriveroa@gmail.comq @g
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