1

The Challenging (Changing) World of

Power Transmission

� What will the Rules be?

� Who will Profit from the Transmission System?

� Who will be Calling the Shots?

The Challenging (Changing) World of Power Transmission

� The Rules will be established

� Someone will Profit from the Transmission System

� The Value of Transmission will Rise

� Investment in Transmission will Rise

Common Denominators

The Challenging (Changing) World of Power Transmission

� New Rules:

� IPP’s

� Transmission Functionally Unbundled

� Wholesale Tariffs

� Regulator to Set Market Rules

� Environmental Constraints

Sweeping Changes-1

The Challenging (Changing) World of Power Transmission

� New Players:

� IPP’s

(Not familiar with Transmission Technology

& Very Aggressive)

� Large Wholesale (non-Utility) Customers

� Power Brokers (New Breed with Greed)

� Transmission Operator

(to provide Point-to-Point Network Services)

Sweeping Changes-2

2

The Challenging (Changing) World of Power Transmission

� New Demands on the Transmission System:

� Power from Unconventional Sources

� Unplanned Directions of Power Flows

� Loop Flows Not Acceptable

� Increase in Demand

� Less Reliance on Traditional Control Mechanisms (Generators, etc.)

Sweeping Changes-3

The Challenging (Changing) World of Power Transmission

� New Services:

� Sophisticated System Controls

� Controls independent of Generation

� Frequent Changes in Controls

� More Wheeled Power without New Lines

� New Ancillary Services (e.g. Reactive Power, Frequency Regulation, etc.)

Sweeping Changes-4

The Challenging (Changing) World of Power Transmission

� New Operating Tools:

� On-Line Security Assessment

� On-Line Impact of Transactions

� Fast & Reliable Telecom (On-Line Information)

� System-wide Monitoring (Synchronised PhasorMeasurements)

� On-Line Diagnoses (e.g. Thermal Limits, etc.)

� Load Management

Sweeping Changes-5

The Challenging (Changing) World of Power Transmission

� New Control Tools:

� SVC’s Additional Control Functions

� Other FACTS Devices

� ???

Sweeping Changes-6

3

VAr Compensation Methods

Conventional Thyristor Switched Voltage Source Converters

Shunt

Series

PhaseShift

VAr Compensation Methods

Conventional Thyristor Switched Voltage Source Converters

Shunt

Series

PhaseShift

� Generators must operate Stably in Synchronism. (Stability Margins)

� Voltages must be kept within Rated Values during normal operation and Remain Stable (Controllable) during Disturbances. (Reactive Power Reserves)

� Temporary Overvoltages should be Limited

� Low Losses (Limit Loop Flows & VAr Transmission/Transfer)

� High Power Transfer Capability

Transmission System Requirements

� Generator Rotor-Angle Stabilities:

� Transient Stability (Large Disturbances)

� Steady State Stability (Small Signal Perturbations)

� Resonances:

� Sub-Synchronous

� Near 50-Hz

� Harmonics & Zero-Sequence

� Voltage/Reactive Power Problems

� Limited Means for Power Flow Control

� Thermal Limits for Lines & Transformers

Power System Limitations

4

� Rule of SVC’s & FACTS:

� Remove Transmission Constraints (within Thermal Limits)

� Q-Dispatch (Reduction of Cost of Losses)

� Improve Power Transmission Security (Satisfy Requirements/Conflicts of Players)

� Provide Custom Power Quality

� Adaptive for inclusion in Local & Central Intelligent Controls

Facing the Challenge Eskom SVC’s

Installations since 1982 until 1997

� 400 kV SVC’s :7

-250/+250 MVAr(5), -100/200 MVAr (1), -200/+150 MVAr (1)

� 275 kV SVC’s :2

-100/+200 MVAr (2)

� 132 kV SVC’s :7

-30/+15 MVAr (7)

Total installed MVAr’s: 4000 MVAr