RCUC and Dispatch Process

Scheduling & Dispatch Workshop

RCUC & The Dispatch Process

Donal Connolly (Eirgrid)Michael Preston (SONI)


Introduction

• Scheduling versus Dispatch

• Immediate Priorities

• Medium Term Priorities and Inputs into the decision to Reschedule or

Redispatch

• Why Dispatch and Schedule may differ

• Load Rise and Night Valley


Scheduling and Dispatch

The output of the scheduling process is:Ø A Unit Commitment scheduleØ A set of discrete MW set points for each unit at 30 minute intervalsØ A reserve schedule for each jurisdictionØ A tie-line flow schedule

The dispatch process:Ø Adheres to Operational Priorities (safety, security, economy)Ø Aims to match demand with generation on a second by second basisØ Maintains tie-line flow schedulesØ Maintains adequate levels of operating reserve at all timesØ Plans for credible generation and transmission contingenciesØ Manages real time system disturbances that cause frequency deviations,

transmission overloads or voltage problems

The Control room operators use the output of the scheduling process to guide them in the dispatch process


Operating the System

When assessing whether the current schedule is adequate to feed into the dispatch process the Operator will give consideration to:

Immediate Priorities

Ø Frequency, Voltage and Flows on Line within limits

Ø Reserve check

Ø Tie Line Flow (actual to RCUC schedule)

Medium Term Priorities

Ø Load comparison (actual to latest forecast to RCUC schedule)

Ø Wind comparison (actual to latest forecast to RCUC schedule)

Ø Generator Availability Changes

Ø Tie Line Flow

Ø Margin Check

If the schedule is not adequate the Operator will prepare a new schedule


Load Comparison

System Demand (06 Aug 07)

1800

2300

2800

3300

3800

4300

4800

00:00 06:00 12:00 18:00

Tim e

MW

s

System Demand (08 Apr 08)

1800

2300

2800

3300

3800

4300

4800

00:00 06:00 12:00 18:00

Tim e

MW

s

System Demand (15 Aug 07)

1800

2300

2800

3300

3800

4300

4800

00:00 06:00 12:00 18:00

Tim e

MW

s

System Demand (18 Dec 07)

1800

2300

2800

3300

3800

4300

4800

00:00 06:00 12:00 18:00

Tim e

MW

s

April Summer

Winter Summer B/H


Wind Comparison

Wind Forecast

0

50

100

150

200

250

300

350

400

450

06:00 14:00 22:00 06:00 14:00 22:00 06:00 14:00 22:00 06:00 14:00 22:00 06:00 14:00 22:00 06:00 14:00 22:00

Time

MW

s

WeProg Forecast at 09/04/2008 00.00 Corrected Morecare Forecast at 09/04/2008 06.00 Actual Wind


Tie Line Schedule


Margin Check

MWMWs Available 4673Short Available 4464To/From SONI 311Wind 114

4889Est. Peak 4000Margin 889

ReservePOR 308 MW (75% of largest in feed, 5 – 15 sec)SOR 308 MW (75% of largest in feed, 15 – 90 sec)TOR1 410 MW (100% of largest in feed, 90 sec – 5 min)TOR2 410 MW (100% of largest in feed, 5 min – 20 min)


Reschedule or Dispatch

Demand ChangeWind Change

Availability ChangeTransmission ContingenciesSignificant

Departure formSchedule

New Schedule isJointly Prepared by SOs

SmallDeparture form

Schedule

Both SOs use a merit order of unitsunder their control, based on incremental price

•To manage real time fluctuations in their control area•Maintain required levels of operating reserve•Maintain tie line flow

The merit order is based on the bids and offerssubmitted by the participants for that trading day.


RCUC to EDIL

RCUC Output

Spreadsheet

EDIL

Gas Indicative Schedule


Unit Trip

Freq. & Tie Line flow 30 Mar 08

49.2

49.3

49.4

49.5

49.6

49.7

49.8

49.9

50

50.1

15:15:00 15:15:30 15:16:00 15:16:30 15:17:00 15:17:30 15:18:00 15:18:30 15:19:00 15:19:30 15:20:00 15:20:30 15:21:00

Time

Hz

-250

-200

-150

-100

-50

0

50

100

150

MW

s

Freq. Tie Line

49.94 Hz

-207 MW

78 MW

49.29 HzTH4 Sync


Dispatch Instructions (Unit Trip)

Sun Mar 30 15:17:31 IST 2008GAS379MWMDMWOFTYC

Sun Mar 30 15:17:04 IST 2008GAS90MWMDMWOFAT14

Sun Mar 30 15:17:39 IST 2008GAS395MWMDMWOFHN2

Sun Mar 30 15:17:39 IST 2008HYDR15MWMDMWOFLI1

Sun Mar 30 15:17:25 IST 2008460MWMDMWOFPBC

Sun Mar 30 15:17:18 IST 2008GAS270MWMDMWOFAD1

Sun Mar 30 15:17:12 IST 2008OIL131MWOFMWOFTB3

Sun Mar 30 15:17:10 IST 2008HYDR21MWMDMWOFAA1

Sun Mar 30 15:16:59 IST 2008HYDR15MWMDMWOFLE1

Sun Mar 30 15:16:39 IST 2008PGEN73MWMDMWOFTH4



Send TimeFuelValueDI Entered TypeDI TypeUnit


Frequency Response

Frequency Response

-100

0

100

200

300

400

14:13:28 14:14:08 14:14:48 14:15:28 14:16:08 14:16:48 14:17:28 14:18:08

Time

MW

s

48.8

49

49.2

49.4

49.6

49.8

50

50.2

Hz

CUSXED_1MMW HUNQHN_2MMW ISHTDB_1MMW LOU3AT1_MMW LOU3AT2_MMW LOU3AT3_MMW LET1STB1MMW COR1EKN1MMW TB_QTB_3MMW CTHXER_3MMW CTHXER_4MMW CLFXER_1MMW CLFXER_2MMW AD_YAT_4MMW LA_SLR_4MMW SH_SWO_4MMW SK_SSK_4MMW AA_XAA_1MMW AA_XAA_2MMW AA_XAA_3MMW AA_XAA_4MMW TH_YTH_2MMW TH_YTH_3MMW TH_YTH_4MMW MR_YMT_7MMW MR_XMR_1MMW PB_XPB_4MMW PB_XPB_5MMW PB_UPB_6MMW AD_QAD_1MMW


Load Comparison

Current Day

Previous Day

Previous Week

MatchCold FrontCold Front


Wind ForecastWind Forecast

0

100

200

300

400

500

600

18:00

:00

02:00

:00

10:00

:00

18:00

:00

02:00

:00

10:00:0

0

18:00:0

0

02:00:0

0

10:00

:00

18:00

:00

02:00

:00

10:00

:00

18:00

:00

02:00

:00

10:00

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18:00

:00

02:00

:00

10:00:0

0

18:00

:00

Time

MW

s

Morecare 24/04/2007 18:00:00 WeProg ACTUAL WIND

Wind Forecast

0

20

40

60

80

100

120

140

160

180

200

00:00

:00

02:00

:00

04:00

:00

06:00

:00

08:00

:00

10:00

:00

12:00

:00

14:00

:00

16:00

:00

18:00

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20:00

:00

22:00

:00

00:00

:00

02:00

:00

04:00

:00

06:00

:00

08:00

:00

10:00

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12:00

:00

14:00

:00

16:00

:00

18:00

:00

20:00

:00

22:00

:00

00:00

:00

Time

MW

s

CURRENT FORECAST 25/06/2005 ACTUAL WIND 24/06/2005 18:00:00 FORECAST24/06/2005 12:00:00 FORECAST 24/06/2005 06:00:00 FORECAST

Wind Forecast

0

100

200

300

400

500

600

700

18:00

:00

20:00

:00

22:00

:00

00:00

:00

02:00

:00

04:00

:00

06:00

:00

08:00

:00

10:00

:00

12:00

:00

14:00

:00

16:00

:00

18:00

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20:00

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22:00

:00

00:00

:00

02:00

:00

04:00

:00

06:00

:00

08:00

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10:00

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12:00

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14:00

:00

16:00

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18:00

:00

Time

MW

s

Corrected CURRENT FORECAST 15/04/2008 18.00 ACTUAL WINDFORECAST 15/04/2008 12.00 FORECAST 15/04/2008 06.00FORECAST 15/04/2008 00.00 Uncorrected Current

•Divergent Forecasts

•Forecast Different from Wind

•Forecast Timing


Met Information


Wind Rising

Load & Wind 27 Mar 08

2500

2700

2900

3100

3300

3500

3700

3900

4100

4300

4500

00:00 06:00 12:00 18:00

Time

MW

s

0

100

200

300

400

500

600

700

Load Wind

400 MW

400 MW

6 Hrs


Contingency Analysis


Load Rise 07 Apr 08

RCUC looks at 30 minute intervals but demand is changing on a second by second basis and the dispatcher must consider how the demand changes when issuing instructions

16398633398609:00

17397008:45

623953226395308:30

164389108:15

1563727331372708:00

175357107:45

1613396382339607:30

221323507:15

1273014204301407:00

77288706:45

282810172281006:30

144278206:15

2638263806:00

Inc in 15 Minutes15 minute intervalsInc in 30 MinutesMWs

06:00 – 09:00 1348 MW

Wind Output and Loss of largest in-feed


Dispatch Instructions 07 Apr 08Unit D I E ntered T ype V alue Eff T im e Status S ender N am e N ew C om m entHN 2 M W O F 318 Mon Apr 07 06 :01 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAD 1 M W O F 159 Mon Apr 07 06 :02 :00 IS T 2008 AC H IE V E D connoly_d M W LoadPB C M W O F 396 Mon Apr 07 06 :04 :00 IS T 2008 AC H IE V E D connoly_d M W LoadMR C M W M N 101 Mon Apr 07 06 :12 :00 IS T 2008 AC H IE V E D connoly_d M in im um D eclared LoadPB C M W O F 366 Mon Apr 07 06 :22 :00 IS T 2008 AC H IE V E D connoly_d M W LoadNW C M W M N 78 Mon Apr 07 06 :26 :00 IS T 2008 AC H IE V E D connoly_d M in im um D eclared LoadHN 2 M W O F 267 Mon Apr 07 06 :30 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAA 2 M W O F 12 Mon Apr 07 06 :33 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAA 2 M W M N 12 Mon Apr 07 06 :33 :00 IS T 2008 NO T_A C HV connoly_d M W LoadTB3 M W O F 170 Mon Apr 07 06 :34 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTB4 M W O F 170 Mon Apr 07 06 :34 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAT14 M W O F 20 Mon Apr 07 06 :55 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAT14 M W M N 15 Mon Apr 07 06 :55 :00 IS T 2008 NO T_A C HV connoly_d M W LoadAD 1 M W O F 201 Mon Apr 07 06 :39 :00 IS T 2008 AC H IE V E D connoly_d M W LoadHN 2 M W O F 308 Mon Apr 07 06 :56 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAA 1 M W O F 12 Mon Apr 07 07 :01 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAA 1 M W M N 12 Mon Apr 07 07 :01 :00 IS T 2008 NO T_A C HV connoly_d M W LoadTB3 M W O F 201 Mon Apr 07 07 :01 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTB4 M W O F 201 Mon Apr 07 07 :01 :00 IS T 2008 AC H IE V E D connoly_d M W LoadHN 2 M W O F 348 Mon Apr 07 07 :02 :00 IS T 2008 AC H IE V E D connoly_d M W LoadHN C M W O F 264 Mon Apr 07 07 :04 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAD 1 M W O F 260 Mon Apr 07 07 :04 :00 IS T 2008 AC H IE V E D connoly_d M W LoadHN 2 M W O F 389 Mon Apr 07 07 :06 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTB1 M W M N 20 Mon Apr 07 07 :05 :00 IS T 2008 AC H IE V E D connoly_d M in im um D eclared LoadPB 1 M W O F 80 Mon Apr 07 07 :09 :00 IS T 2008 NO T_A C HV connoly_d M W LoadTB2 M W O F 51 Mon Apr 07 07 :12 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTH2 M W O F 0 Mon Apr 07 07 :17 :00 IS T 2008 AC H IE V E D connoly_d D e-synch . Un itG I1 M W M N 28 Mon Apr 07 07 :16 :00 IS T 2008 AC H IE V E D connoly_d M in im um D eclared LoadTB3 M W O F 222 Mon Apr 07 07 :21 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTB4 M W O F 222 Mon Apr 07 07 :21 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTH3 M W O F 0 Mon Apr 07 07 :23 :00 IS T 2008 AC H IE V E D connoly_d D e-synch . Un itTH4 M W O F 0 Mon Apr 07 07 :31 :00 IS T 2008 AC H IE V E D connoly_d D e-synch . Un itTH2 M W M N 5 Mon Apr 07 07 :32 :00 IS T 2008 AC H IE V E D connoly_d M in im um D eclared LoadTH2 M W O F 0 Mon Apr 07 07 :32 :00 IS T 2008 NO T_A C HV connoly_d M in im um D eclared LoadTH3 M W M N 5 Mon Apr 07 07 :33 :00 IS T 2008 AC H IE V E D connoly_d M in im um D eclared LoadTH3 M W O F 0 Mon Apr 07 07 :33 :00 IS T 2008 NO T_A C HV connoly_d M in im um D eclared LoadTB3 M W M D 256 Mon Apr 07 07 :35 :00 IS T 2008 AC H IE V E D connoly_d M axim um D eclared LoadTB4 M W M D 256 Mon Apr 07 07 :35 :00 IS T 2008 AC H IE V E D connoly_d M axim um D eclared LoadPB 1 M W O F 101 Mon Apr 07 07 :36 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTB1 M W O F 54 Mon Apr 07 07 :36 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAA 3 M W M D 19 Mon Apr 07 07 :37 :00 IS T 2008 AC H IE V E D connoly_d M axim um D eclared LoadER 1 M W O F 9 Mon Apr 07 07 :40 :00 IS T 2008 AC H IE V E D connoly_d M W LoadER 1 M W M N 4 Mon Apr 07 07 :40 :00 IS T 2008 NO T_A C HV connoly_d M W LoadER 3 M W M D 23 Mon Apr 07 07 :40 :00 IS T 2008 AC H IE V E D connoly_d M axim um D eclared LoadER 3 M W M N 5 Mon Apr 07 07 :40 :00 IS T 2008 NO T_A C HV connoly_d M axim um D eclared LoadHN C M W O F 295 Mon Apr 07 07 :40 :00 IS T 2008 AC H IE V E D connoly_d M W LoadPB C M W O F 406 Mon Apr 07 07 :43 :00 IS T 2008 AC H IE V E D connoly_d M W LoadER 2 M W O F 9 Mon Apr 07 07 :53 :00 IS T 2008 AC H IE V E D connoly_d M W LoadER 2 M W M N 4 Mon Apr 07 07 :53 :00 IS T 2008 NO T_A C HV connoly_d M W LoadER 4 M W M D 23 Mon Apr 07 07 :53 :00 IS T 2008 AC H IE V E D connoly_d M axim um D eclared LoadER 4 M W M N 5 Mon Apr 07 07 :53 :00 IS T 2008 NO T_A C HV connoly_d M axim um D eclared LoadHN C M W O F 308 Mon Apr 07 07 :55 :00 IS T 2008 AC H IE V E D kearney_s M W LoadPB C M W O F 436 Mon Apr 07 07 :57 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTH4 M W O F 45 Mon Apr 07 08 :03 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTH4 M W O F 0 Mon Apr 07 08 :03 :00 IS T 2008 NO T_A C HV connoly_d M W LoadTH4 M W M N 5 Mon Apr 07 08 :03 :00 IS T 2008 NO T_A C HV connoly_d M W LoadAT14 M W O F 39 Mon Apr 07 08 :05 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAA 2 M W M D 22 Mon Apr 07 08 :05 :00 IS T 2008 AC H IE V E D connoly_d M axim um D eclared LoadAT11 M W O F 20 Mon Apr 07 08 :25 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAT11 M W M N 15 Mon Apr 07 08 :25 :00 IS T 2008 NO T_A C HV connoly_d M W LoadPB C M W O F 456 Mon Apr 07 08 :08 :00 IS T 2008 AC H IE V E D connoly_d M W LoadTH3 M W O F 45 Mon Apr 07 08 :15 :00 IS T 2008 AC H IE V E D connoly_d M W LoadAT14 M W O F 60 Mon Apr 07 08 :20 :00 IS T 2008 AC H IE V E D connoly_d M W LoadGI2 M W M N 28 Mon Apr 07 08 :15 :00 IS T 2008 AC H IE V E D connoly_d M in im um D eclared LoadAT11 M W O F 39 Mon Apr 07 08 :37 :00 IS T 2008 AC H IE V E D connoly_d M W LoadGI1 M W O F 52 Mon Apr 07 08 :40 :00 IS T 2008 NO T_A C HV connoly_d M W LoadAA 4 M W M D 24 Mon Apr 07 08 :42 :00 IS T 2008 AC H IE V E D connoly_d M axim um D eclared Load

As can be seen here, to manage a typical morning load rise the operator had to issue 55 separate MW instructions over a 2 and ½ hour period.


Night Valley 06 May 07

This table shows the problems faced by the operator when all plant is dispatched to Minimum Load. The operator may have to de-commit plant in an unscheduled way due to unexpected increases in wind

output, decreases in system demand, generator limitations or a combination of all of these.

Unit Output Avail Unit Output Avail Unit Output Avail Unit Output Avail Unit Output Avail Unit Output Avail Unit Output AvailGI1 55 AD1 40 270 AP5 52 BK1 AA1 21 TH1 -69 73GI2 AT1 90 AT1 88 BK2 AA2 22 TH2 -71 73GI3 100 AT2 AT2 ED1 52 90 AA3 19 TH3 -70 73TB1 60 AT4 AT4 AA4 24 TH4 -70 73TB2 60 MRC 112 MRC 112 CL1 4TB3 42 246 ER1 10TB4 230 NWC 133 NWC ER2 10

MP1 MP1 NW5 NW5 ER3 23MP2 145 305 MP2 PB1 133 ER4 23MP3 155 305 MP3 PB2 41 118 LE1 15

PB1 PB3 LE2 4PB2 118 PB4 88 149 PB4 LE3 8PB3 PB5 87 147 PB5 LI1 15

PB6 127 170 PB6 LI2 15DB1 357 397 LI4 4HNC 227 333 170 LI5 4HN2 HN2 LR4

TP1 52 WO4 121 150SK3 41 81SK4 41 81TYC

RP1 52RP2 52

Coal 300 610 Oil 42 869 Gas 1049 1636 Dist 599 Native 173 240 Hydro 221 TH -280 292

Wind 451 SONI -237 System Demand 1972


Summary

Ø The Scheduling Process feeds into the Dispatch Process

Ø Operators take a number of real-time factors into account when issuing dispatch instructions

Ø Time permitting, Operators will re-schedule if the current schedule cannot be followed

Ø Operators will face unplanned issues when dispatching

Ø At all times operators give priority to safety and security

Documents

RCUC and Dispatch Process