Redispatch

Redispatch is the process of adjusting generator outputs away from their market-determined or scheduled positions to relieve transmission congestion, resolve voltage issues, or maintain overall system security. It is a corrective action taken by system operators when the market outcome would otherwise lead to constraint violations on the network.

Key Aspects of Redispatch:

• Counter-Trading Mechanism: Redispatch works by instructing generators on one side of a constraint to reduce output (downward redispatch) while generators on the other side increase output (upward redispatch) by an equivalent amount, keeping total generation balanced while rerouting power flows away from the congested path.
• Cost Implications: Because redispatch replaces cheaper generation with more expensive generation, it raises total system costs. In Europe, redispatch costs have grown significantly, reaching several billion euros per year in countries like Germany, driven by growing renewable generation far from load centers.
• Cost Allocation: Different markets handle redispatch costs differently. Some socialize costs among all network users through grid tariffs; others assign costs to the generators or market participants causing the congestion, creating locational signals to influence future siting decisions.
• Cross-Border Coordination: In interconnected systems like the European grid, congestion on one country's network can be most efficiently resolved by redispatching generators in a neighboring country, requiring coordinated processes and cost-sharing agreements between transmission system operators (TSOs).
• Network Model Dependency: Effective redispatch requires accurate, up-to-date network models that correctly predict power flows under different generation patterns. Errors in the network model can lead to unnecessary or insufficient redispatch, increasing costs or leaving the system insecure.