Optimizing Risk-Aware Bidding Strategies for EV Fleets in the 15-Minute Nordic mFRR Market

Sammanfattning

The transition to a carbon-neutral Nordic power system, characterized by high shares of variable renewable generation, requires flexible resources that can respond within minutes. Aggregated fleets of electric vehicles (EVs) offer such flexibility but have yet to be fully integrated into balancing markets. This thesis develops a risk-aware bidding framework that enables an EV aggregator to participate in the Nordic 15-minute Manual Frequency Restoration Reserve (mFRR) Energy Activation Market introduced in March 2025. A multi-stage mixed-integer linear stochastic optimization model is proposed to determine profitable and feasible bids, while respecting the operational constraints of the EV fleet. Two formulations are analyzed: (i) a fixed energy schedule, where the charging plan is determined separately and treated as a commitment, and (ii) a joint spot and reserve approach, where the energy schedule is optimized together with reserve bids. Conditional Value-at-Risk (CVaR) is incorporated to penalize outcomes with low profit, enabling the aggregator to trade-off expected gains against downside risk. A case study of 1 000 Swedish EVs with typical home-charging patterns shows that participation in the mFRR market can greatly reduce charging costs when the spot schedule is fixed. When spot and reserve bids are instead optimized jointly, the aggregator can even profit from the charging process by fully leveraging the fleet’s flexibility. Introducing risk aversion reduces downside risk with only a minor impact on expected profit.