International Meeting onVery Large Power Systems

State Grid of China

Beijing, China

October 25-25, 2005

Presentation

Brazilian National InterconnectedPower System Operation

Luiz Eduardo BarataOperational Director

ONS – Operador Nacional do Sistema Elétrico – Brazilian ISO

2

Operating Environment:

The Brazilian National Interconnected Power

System – SIN Characteristics

3

Production & Market Data – 2004 – National Integrated Power System - SIN

Integrated Operation by the Independent System Operator Introduces 25 % of Synergic Gains

Isolated Systems 2% of the Brazilian

Market

2002 2004 2008

Installed capacity – MW 74,670 79,579 93,546

Hydro 63,834 66,429 75,315

Thermal-conventional 8,829 11,143 13,301

Nuclear 2,007 2,007 2,007

Renewable (Proinfa) 3,270

Max, Demand – MW 50,759 58,816 72,788

Production – TWh 347,5 384,1 468,7

TLs ≥ 230 kV – km 72,506 80,022 90,347

No. of circuits 614 693 775

No. of substations 303 321 351

Transformer capacity (GVA) 166 178 195

Customers – millions 47 52

Annual Revenue - US$/bi 19,3 24,2

4

SIN Relative size

Brazilian Transmission system x European

1 cm + 260 km365.9 468.2 248.0 376.0 319.7-

100

200

300

400

500

600

Brazil France Spain UK Italy

TW

h

Production (TWh) – 2003

5

Main Transmission Grid Role

The Main Grid in the SIN, due to the hydroelectricity predominance and power plant locations far from load centers, besides the power transport role:

Is the main vector of system economical optimization:

Allows for hydrothermal optimal dispatch and optimal use of reservoir storage, by exploring basin hydrological complementarities - adding synergic gains – more than 20% of the system's assured energy

Helps postpone important generation expansion investments

The Main Grid can be seen as:

A virtual power plant located at the border of power import regions

2004-2006 Configuration

LegendExistent Future Complex

3,45

0 km

2,780 km

Isolated Systems2% of Brazilian

market

6

Subsystems Integration in Brazil – Evolution of Imports Capacity and Energy Demand by Subsystem

(1) Itaipu as a Southeast/Midwest subsystem power plant

NorthNortheast

Southeast / Midwest

South

(1) Itaipu Binational

Integration leads toenhanced system security

Integration also leads toenhanced supply security

7

The National Interconnected System

Operator – ONS

8

What ONS does – Attributions and Macro Functions

National Interconnected

System – SIN Operations

Planning and Scheduling

Real Time Operations

Transmission Services

Administration

Operations planning and scheduling and optimal centralized generation dispatch

Supervision and coordination of utilities system operations centers

Operations supervision and control of the national power systems and international interconnections

Contracting and administration of transmission services, grid access and ancillary services

Proposition to MME of main grid installations upgrading and reinforcements

Definition of main grid operations rules

Issuing of actual dispatch performance statistics, for ANEEL auditing

Macro functio

ns

Macro functio

ns

Tight Pool operation

Transmission system owned by utilities

Attributio

ns

Attributio

ns

9

ONS activities chain

Grid procedures Operations rules

Proposes of Main Grid

upgrading & Reinforcements

(*)

Planning

Generation Operations Planning

Operation

Transmission Services

Accounting and Settling

Inputs from utilities

products

Pre-operation

Real time operation

utilities consumers

Electrical Operations Planning

Post-operation analysis

3 years ahead

Under demand Up to 5 years

ahead

Monthly, weekly and daily

During the day / real time

(*) Mandatory after ANEEL approval

Access andConnection

to grid

Operation Scheduling

10

ONS Control Centers Location and Hierarchy

ONS presently has 1 National

Control Center – CNOS, 4 Regional

Control Centers, 1 for each of SIN’s

subsystems, and 4 Local Control

Centers

ONS is responsible for:

systems operations of Main Grid

and centralized dispatched power

plants (> 30MW), while Utilities are

responsible by installations

operations;

Management of power grid above

230 KV

Recife

Brasília

Rio de Janeiro

Florianópolis

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SIN Reliability:

ONS Experience

Permanent concern with all time frames

Expansion planning, Operation planning, Operation scheduling, Real Time operation, Post operation

Centralized Transmission Planning adjustments

Grid Procedures – Processes, Rules and Standards

- Requirements for substations arrangements & protection

- Requirements for generating units characteristics and controls

- Requirements, rules and procedures for new accessing Agents to the Main Grid

- Performance standards

Reliability – ONS Experience

13

Improvement of intrinsic characteristics of the existing substations, by means of refurbishing bus configurations, transpositions of circuits and other measures aimed at reducing the impact of large disturbances (11 Main Grid substations refurbished in the period 2000-2003);

Strategic installations identification related to system performance (84 out of 398 substations);

Constant upgrade of installations Control & Protection; Upgrading of system controls (around 250 special

protection systems and 4 regional interconnections out-of-step relays);

Yearly revision of controllers settings in the Brazilian major power plants (80 power plants);

Emergency dispatch evaluation; Implementation of observability and controlability

capacities

Reliability – ONS Experience

14

More extensive use of special protection systems (SPS) is relevant as demonstrated by experience

209 229 268 288

0

100

200

300

2002 2003 2004 2005(By september)

Nº

of

SP

S

Evolution of SPS in the SIN Period of 2005/2006

Revisions 21

Already implanted - 2005

Example: 440 kV double circuit loss

20

Being implanted 22

In planning and conception phase

88

Blackout avoided: 1 - 06/14/05 Nine 765 kV towers down at

Itaipu;2 - 08/11/05 Isolation of Tucuruí Hydro

Plant from SIN.

- Importance of participation: T, D and G Agents;

- ANEEL meeting – Set/05 to improve Resolution 158.

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SIN Safety Status

1. Measures designed to minimize the probability of the occurrence of large disturbances.

Such measures must be effective in reducing the severity of events.

2. Measures designed to minimize the propagation of unavoidable disturbances.

Such measures must be effective in restricting the immediate spatial and temporal effects of the events.

3. Measures designed to minimize load restoration times.

These measures must be effective in reducing the load restoration times to the limits considered acceptable from the consumers point of view.

Based on three pillars

Brazilian Defense PlanPreventive Grid Corrective Actions

Disturbance AnalysisReproduction of disturbances through digital toolsIdentification of corrective measures and preventive actions

Follow-up of recommendations implementation Statistical analysis and protection performance

evaluation systems

Indices - Some examples:- Number of disturbances;- Geographical extension;- System robustness degree;- Non-supplied energy;- Severity (system, minute);- Average and total restoration times.

Analysis of events with no load-loss

Operating SecurityPost Operation Actions

By set of disturbances (aggregated time analysis)

By disturbance (individual analysis)

Control Centers Instrumentation and Personnel Training

The main efforts of ONS are focusing on:

Improving measurement system, in a joint Utilities-ONS project

Implement in ONS control centers a tool to dynamically assess system security and indicate corrective actions

Permanent system operators training on use of control room available support tools (and improvements)

Implementation of system operators training simulator tool

Effective restoration time in 1999 and 2002 blackouts

Indices – Some Examples

Power Quality / Continuity:

Average freq. & duration of SIN outages

System robustness degree (SRD) – Percentage of disturbances in the Main Grid with no load shedding related to the total number of disturbances:

Indices – Some Examples

YearSRD

200060%

200385%

200488,6%

Frequency (times/year): 1.6 (2000) to 1.4 (2003)Duration (hours/year): 2.8 (2000) to 2.2 (2003)

Frequency 2004 (times/year): 1.03Duration 2004 (hours/year): 2,04

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Main Challenges

Define criteria to technical-economical optimal level of system security / reliability

Improve criteria to balance system electrical security and economically optimal generation dispatch

Evaluate adequacy of present risk of supply value of 5% to be used in system expansion planning

Policy and Regulations

Power Industry and Consumers

Regulations ISO Regulatory framework

Ensure system optimal dispatch considering commercial interests of each utility

Acceptance by utilities of disturbance analysis conclusions/recommendations

For key substations – to assure system reliability, how to manage the legitimate utility proposal by fully automated (unmanned) systems

During system post-disturbances recovery, how to manage the utilities operator’s reactions to non-explicitly defined situations cited in operations instructions

Manage the balance between environmental requirements and power system operation

Operations Environment

Operator and Utilities

Difficulties of utilities (time table and investment) to upgrade or reinforce older installations

Definition of load shedding schemes

Ensure system optimal operation face to increasing environmental restrictions

Ensure same reliability level for all system areas

Ensure a reliable measurement system

Ensure reliable protection systems

Ensure the use of adequate new technologies regarding system models, system applications and simulators

Ensure the use of new technologies to provide system operations flexibility and controllability regarding to power system equipment, protection and control, measurement and communications systems

Technical / Operational