Energy Digest

A simplified model of a line-commutated converter high-voltage direct current (LCC-HVDC) system connected to a weak grid is proposed and validated. The addition of a grid-forming controlled voltage source converter (GFM-VSC) provides stabilizing impact on the stability of the LCC-HVDC link in weak grid conditions, even with modest capacity relative to the total nominal apparent power. Sizing of the GFM power converter sufficient to ensure system stability is found to be as little as a share of the total nominal apparent power of the LCC-HVDC and GFM-VSC.

The simultaneous solution of switched DAEs in power system transient simulation may experience convergence loss after discontinuous events due to poor initialization, but a new method has been developed to address this issue by using homotopy-continuation based globalized re-initialization. The proposed scheme is validated through numerical simulations and shows reliable recovery of convergence in cases where direct post-event solution fails. It clarifies why standard methods may fail at discontinuities.

The GIST 2064-bus test system is a publicly available, synthetic model of the Korean power grid, derived from open-source data, with 2064 buses, 512 generation sources, and 3044 AC line circuits. The model has been solved using a general-purpose solver to find an operating point that meets 85 GW of demand, with minimal losses and no undervoltage buses. The dataset, maps, and tooling are released as a platform for power flow, planning, and decarbonization studies.

Probabilistic forecasting models are being increasingly deployed on complex power systems with distinct channel physics and operational constraints. A new benchmark called PowerPhase has been introduced, which evaluates both property at scale by forecasting up to 36,964 channels across six transmission grids. This benchmark highlights the need for a trade-off between safety (predicting outcomes) and fidelity (ensuring model accuracy).

A multi-phase optimization framework is presented for jointly planning charging stations in a shared network to minimize costs while meeting predefined electrification targets. Early-stage infrastructure deployment supports fleets with concentrated operations, while later expansion phases accommodate long-haul and dispersed transport demand. The analysis highlights the importance of coordinated and data-driven infrastructure planning in enhancing freight transport electrification efficiency.

European green hydrogen production is threatened by strict power purchase rules on renewable sourcing, which can jeopardize offtake agreements and increase production costs. Relaxing temporal correlation rules or increasing offtake flexibility could mitigate business risks, but may come with increased costs. Extended transitional rules could support the ramp-up of European green hydrogen production without exceeding emission intensity thresholds.

A two-node stochastic resource system operates with uncertain supply and demand, requiring finite storage to maintain prescribed limits with high probability. The optimal transport policy involves a critical transport-capacity threshold below which full risk pooling between nodes is possible, decreasing as the operating horizon increases. This enables progressively smaller transport capacity to achieve full-pooling performance over longer horizons.

Floating solar photovoltaic systems offer a high potential for expanding clean electricity access in energy-poor South America, with estimated yields of 1,500-2,000 kWh per kW annually. The technology has the potential to reduce emissions and costs when compared to fossil generation, with competitive prices emerging when accounting for avoided land use and water benefits. FSPV systems could also be co-located with hydropower and AI data centers, offering a scalable model for deployment in underserved regions.

Controlling wind farm power output can help regulate the power grid frequency by dividing a target signal into individual setpoints and applying each turbine's controller accordingly. Proportional dispatch is used to allocate power reserves fairly among turbines, but its effectiveness is limited due to wake effects in wind farms, requiring iterative application. An iterative process (IPD) that converges to equalized reserves is shown to closely approach max-min fairness with a relatively low computational cost.