1. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 TRANSMISSION ACCESS AND CONGESTION MANAGEMENT O. Lavoine-RTE-France

2. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 What is congestion ? First of all, congestion is an operational technical problem : the network can not accommodate all the requested withdrawals and injections, due to the fact that security criteria must be respected : N-1 or more, Voltage.

3. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 Technical means to solve a congestion In the daily operation : Topological modifications, Modification of the requested withdrawals and injections (by re-dispatching). In a longer term : Modifications of the maintenance plans (for generation plants and for network elements), Development of new lines (when possible !).

4. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 Main economical consequences of a congestion Low electricity price zone High electricity price zone Congestio n : lack of capacity In a competitive markets on both sides of the congestion If in the south, the market is not competitive Decoupling of markets, Congestion rent = Difference of price * Transmission Capacity Low electricity price zone Market power of some power plants Need of a strong regulation to reduce market power !

5. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 Two majors different situations An easy situation : The congestion is inside a control area, All technical means can be controlled by one centralized control centre. A much more difficult situation : The congestion is at the limit of two (or more) countries, There is a strong need to co-ordinate control centres and market mechanisms.

6. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 Economic principles The treatment of congestion should respect the following theoretical economic principles: Efficiency (application of nodal pricing approaches ?), Limit power markets, No discrimination. Practically, any system must be easily understandable by concerned users.

7. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 Example of an internal congestion : South-East of France Congestion N-1 line 400 kV line Marseilles Nice Toulon 225 kV line Rhône Valley Boutre

8. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 Example of an international congestion : The Alps to Italy Limited Capacity (The Alps ) Italy : high price France, Germany, Switzerland : low price

9. International Council on Large Electric Systems Brasilia Workshop 22 September 2003 CIGRE C5 objectives CIGRE SC 5 has formed a dedicated WG to congestion questions with experts coming from many different countries. A first objective is to have a worldwide state of art of experiences. A second objective is to classify these experiences according to different situations. Each time, national and international situations have to be considered.