Flexible Training Workloads in Large-Scale AI Data Centers for Transient-Stability Support in Transmission-Constrained Power Systems

• Individual AI data centers may require several hundred megawatts or more, while geographic concentration intensifies transmission congestion and planning constraints.Source: §I · p. 1
• Existing grid-interactive data-center studies mainly use flexibility to smooth, shift, delay, or curtail electricity consumption rather than increase demand.Source: §I · p. 1
• The stabilizing mechanism and its dependence on response timing, magnitude, and electrical location had not been systematically evaluated.Source: §I · p. 2
• TILS initiates or resumes flexible AI training workloads after fault clearing to increase active-power demand at electrically effective locations and limit first-swing generator acceleration.Source: §I · p. 2
• TILS is evaluated in SMIB, IEEE 39-bus, and Korean systems, with response magnitude, activation delay, and electrical siting quantified.Source: §I · p. 2
• 665 MW is the baseline transient-stability-constrained generation limit in the modeled SMIB system, whereas 670 MW results in loss of synchronism.Source: A. Transient-Stability Constraint… · p. 3

• Pre-staged or paused training jobs can be initiated or resumed on command, subject to computing capacity and electrical headroom.Source: B. Operating Principle of the Proposed… · pp. 3–4
• The resulting AI data-center demand increase raises Plocal and therefore increases generator electrical output Pe during the critical post-fault interval.Source: B. Operating Principle of the Proposed… · p. 4
• TILS repurposes rapid AI data-center demand increases, typically viewed as grid-reliability challenges, as targeted post-disturbance transient-stability support.Source: B. Operating Principle of the Proposed… · p. 4

• TILS is most effective where induced load most strongly raises the electrical output of generators undergoing post-fault acceleration.Source: C. Electrical Siting of TILS · p. 4
• In the SMIB system, sending-end load increases directly raise Plocal and Pe, reducing accelerating power without an equivalent increase in weakened-corridor transfers.Source: C. Electrical Siting of TILS · p. 4
• The SMIB case therefore places the AI data center at the sending-end bus so its response directly increases local absorption and the affected generator’s electrical output.Source: C. Electrical Siting of TILS · p. 4

• TILS is represented as an ideal step increase in active-power demand initiated after a prescribed delay following fault clearing.Source: D. TILS Modeling and Activation Delay · p. 4
• The effective end-to-end activation delay combines disturbance detection, signal transmission, workload scheduling, and load activation.Source: D. TILS Modeling and Activation Delay · p. 4
• The step magnitude represents the aggregate load increase from activated training workloads and is varied to evaluate different TILS response magnitudes.Source: D. TILS Modeling and Activation Delay · p. 4
• Finite ramp-up, staged server activation, and workload-level dynamics are omitted; shorter delays suppress acceleration more effectively, whereas longer delays reduce TILS’s stabilizing effect.Source: D. TILS Modeling and Activation Delay · p. 4

Stability criteria and metrics

• Transient stability is assessed from post-fault rotor-angle trajectories, with instability identified by loss of synchronism.TILS effectiveness is quantified by the increase in maximum generation accommodated without synchronism loss under the specified contingency.Source: E. Stability Assessment and Evaluation… · p. 4

Case studies

• The study examines SMIB, IEEE 39-bus, and large-scale Korean systems under system-specific fault or contingency scenarios.The SMIB and 39-bus faults are cleared after 0.1 s; the Korean case uses a severe 765-kV transmission-line contingency.Source: A. Case Study Overview · p. 4, 1) Contingency Scenarios: • · p. 4

Activation timing

• Baseline TILS activation delay is 0.05 s in the SMIB and 39-bus systems and approximately 0.0667 s in the Korean system.The Korean baseline corresponds to four cycles and reflects the response time of the operational special protection scheme.Source: 2) TILS Activation Delays · p. 5

TILS siting configurations

• Siting comparisons place TILS at sending-end, terminal, remote, distributed, or near-generator locations to isolate electrical-location effects.The 39-bus comparison applies identical operating conditions, contingencies, and 100 MW responses at Bus 32 and Bus 10.Source: 3) TILS Siting Configurations: • · p. 5

System-specific metrics

• Generation limits are defined by maintaining synchronism: sending-end generation for SMIB, Bus 32 output for the 39-bus system, and eastern-area aggregate generation for Korea.The Korean metric uses bounded versus diverging systemwide rotor-angle spread and evaluates response magnitude, siting, and delay.Source: 4) Stability Criteria and Performance… · p. 5

Baseline

• 665 MW is the baseline transient-stability-constrained generation limit in the SMIB system.The limit is determined from rotor-angle responses following a severe fault cleared by tripping one transmission line.Source: B. SMIB System · p. 5

Mechanism

• 3 MW of TILS stabilizes the otherwise unstable 670 MW operating point when activated 0.05 s after fault clearing.The local load increase raises generator electrical output during the first swing and reduces the accelerating-power imbalance.Source: B. SMIB System · p. 5, Figure 3 · p. 6

Response magnitude

• 66 MW of TILS enables stable operation at 715 MW, 50 MW above the 665 MW baseline limit.This response corresponds to approximately 10% of the baseline generation limit.Source: B. SMIB System · p. 5

Contextual comparison

• A 530 MW TILS response reaches the 1,025 MW generation limit obtained by adding a third identical transmission line.The comparison illustrates potential stabilizing magnitude under the specified contingency but does not imply functional equivalence.Source: B. SMIB System · pp. 5–6

Activation delay

• The required TILS response at 715 MW rises from 66 MW to 433 MW as additional activation delays increase from 0.1 to 0.5 s.The reported sequence is 87, 120, 177, 273, and 433 MW for additional delays of 0.1, 0.2, 0.3, 0.4, and 0.5 s, respectively.Source: B. SMIB System · p. 6

• A three-phase fault at Bus 10, cleared by tripping the line between Buses 10 and 11, makes the Bus 32 generator the critical generator.Without TILS, increasing Bus 32 output beyond 690 MW causes instability.Source: C. IEEE 39-Bus System · p. 6
• A 100 MW TILS response at either Bus 32 or Bus 10 increases the stability-constrained output of the Bus 32 generator, with Bus 32 providing the larger increase.The Bus 10 case still supports first-swing stability despite being away from the critical generator’s terminal bus.Source: C. IEEE 39-Bus System · p. 6
• Electrical siting matters because TILS at Bus 32 produces a larger generation-limit increase than the same response at Bus 10.The comparison demonstrates that electrically effective locations provide stronger support.Source: C. IEEE 39-Bus System · p. 6
• The stabilizing effect decreases nonlinearly as activation delay increases, while the performance difference between the two locations narrows at longer delays.The results identify early activation and electrical siting as key design considerations.Source: C. IEEE 39-Bus System · p. 6

• The eastern generation area is limited to approximately 11.5 GW, about 60% of installed capacity, because the specified 765-kV contingency may cause eastern generators to lose synchronism.This operating condition is used to assess whether TILS can increase the transient-stability-constrained regional generation limit.Source: D. Korean Power System · p. 7
• Without TILS, the systemwide rotor-angle spread diverges under the contingency, whereas it remains bounded when TILS is activated.The bounded response indicates preserved synchronism under the same operating condition and contingency.Source: D. Korean Power System · p. 7
• Fig. 7 compares generation-limit increases against TILS magnitude across four activation-delay conditions, while retaining a consistent y-axis tick interval despite differing panel ranges.The panels represent baseline delay and additional delays of 0.2, 0.4, and 0.6 s.Source: Figure 7 · p. 8
• Increasing TILS magnitude at baseline delay increases the eastern-area generation limit, with near-generator siting generally outperforming distributed siting.The locational difference demonstrates the importance of electrical effectiveness.Source: D. Korean Power System · p. 8
• As activation delay increases, TILS provides less stabilization and requires a larger response to achieve the same generation-limit increase.The performance gap between near-generator and distributed configurations also narrows at longer delays.Source: D. Korean Power System · p. 8

• TILS uses upward demand flexibility by initiating flexible training workloads during the critical post-fault period, reducing first-swing generator acceleration.Source: A. Implications for Power System… · p. 8
• Across SMIB, IEEE 39-bus, and Korean systems, TILS is most effective when sufficient upward response is available at electrically effective locations and activated rapidly.Source: A. Implications for Power System… · p. 8
• TILS complements rather than replaces braking resistors, energy-storage systems, and special protection systems as a transient-stability measure.These conventional measures use energy absorption or corrective actions such as generator tripping, turbine-valve control, and controlled separation.Source: A. Implications for Power System… · p. 8
• Reserving part of AI data centers’ upward response capability could let computing facilities provide additional coordinated power-system stability support.The option uses flexibility in facilities primarily installed for computing services rather than a dedicated stability-support device.Source: A. Implications for Power System… · p. 8
• In the Korean eastern generation region, TILS can supplement SPS-based generator tripping and increase generation that remains online after a severe contingency.Source: A. Implications for Power System… · p. 8

• Fast activation, pre-contingency upward-response capability, and siting near generators dominating post-fault instability are principal requirements for TILS deployment.Electrically remote loads may still help, but generally with reduced effectiveness.Source: B. Deployment Requirements,… · p. 8
• Implementation requires operators to monitor committed TILS magnitude and availability while data centers receive contingency signals and activate pre-staged training jobs.The committed capability must reflect electrical headroom and flexible-workload status.Source: B. Deployment Requirements,… · pp. 8–9
• The study uses an idealized step increase in demand, whereas actual responses may include finite ramp rates, communication delays, scheduling delays, and sequential workload activation.Observed subsecond AI workload variations do not yet demonstrate reliable grid-triggered multi-megawatt TILS activation.Source: B. Deployment Requirements,… · p. 9
• A component-based estimate gives approximately 0.16 s for aggregate pre-staged GPU activation after fault clearing, but the complete response chain still requires multi-megawatt demonstration.Future validation should cover disturbance detection, signal transmission, workload activation, and delivered-power verification.Source: B. Deployment Requirements,… · p. 9
• TILS or analogous flexible-load controls require system-specific dynamic studies, particularly where generation-area transfer is transient-stability constrained and controllable loads strongly influence accelerating generators.Source: B. Deployment Requirements,… · p. 9

Workload flexibility

• Training workloads provide greater temporal and scheduling flexibility than latency-sensitive inference workloads.This flexibility makes training workloads more suitable for grid-triggered activation.Source: C. Operational Suitability of AI… · p. 9

Available power headroom

• Operational inference clusters retain substantially greater power headroom than training clusters, leaving capacity for additional electrical load.Measurements from operational LLM clusters support the availability of this headroom during inference operation.Source: C. Operational Suitability of AI… · p. 9

Inference coexistence

• GPU time-sharing can use unused capacity for training workloads while preserving primary inference-service performance.This provides a practical basis for adding training load without compromising the primary inference service.Source: C. Operational Suitability of AI… · p. 10

Operational implementation

• Pre-staged training workloads can be activated when grid support is required while inference remains the primary service.The proposed operating arrangement uses flexible training workloads as controllable TILS resources in mixed-use data centers.Source: C. Operational Suitability of AI… · p. 10

Stability-support role

• TILS increases active-power demand after fault clearing, enabling accelerating generators to supply more electrical power and limiting first-swing rotor-angle excursions.The strategy was evaluated from an SMIB mechanism study through the IEEE 39-bus and large-scale Korean systems, where it increased the transient-stability-constrained generation limit.Source: §V · p. 10

Response design

• Earlier activation and siting at buses with stronger electrical influence on critical generators produce larger generation-limit increases.The benefit depends on response magnitude, activation delay, and electrical siting.Source: §V · p. 10

Deployment boundary

• TILS is complementary to transmission reinforcement and established corrective controls, requiring sufficient headroom, flexible workloads, reliable triggering, and system-specific validation.Practical deployment also requires end-to-end validation of multi-megawatt grid-triggered responses.Source: §V · p. 10