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arxiv: 2605.21691 · v1 · pith:CQV5OUVHnew · submitted 2026-05-20 · 📡 eess.SY · cs.SY

Resilient Energy-Based Control for DC Data Centers under Grid and Load Disturbances

Lizhi Wang , Fei Feng , Ella Chou , Yashen Lin This is my paper

Pith reviewed 2026-05-22 08:48 UTC · model grok-4.3

classification 📡 eess.SY cs.SY
keywords passivity-based controlPort-Hamiltonian systemsDC data centersenergy shapingAC-DC convertersvoltage regulationgrid disturbancesload disturbances
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The pith

A Port-Hamiltonian energy-shaping controller makes AC-DC converters passive and stable even with non-passive loads and varying grid conditions.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper develops a passivity-based control method for AC-DC converters that supply Information Technology rack loads in DC data centers. It begins from the total energy balance of the converter and applies a Port-Hamiltonian description to shape stored energy while adding virtual damping through a lossless interconnection. This produces a closed-loop system that remains passive and dissipates energy even when loads are non-passive or the grid voltage and frequency change. A reader would care because conventional cascaded controllers lose guarantees away from nominal points, whereas this method promises asymptotic voltage regulation and faster recovery under realistic faults and load swings shown in simulations.

Core claim

The central claim is that shaping the stored energy and injecting virtual damping via a lossless interconnection with a Port-Hamiltonian controller renders the converter passive. The resulting closed-loop system therefore guarantees asymptotic voltage regulation and strict energy dissipation. These properties hold without any assumption that grid voltage or frequency remains constant and continue to hold when the converter supplies non-passive loads.

What carries the argument

A Port-Hamiltonian controller that shapes stored energy and injects virtual damping through lossless interconnection with the converter dynamics.

If this is right

  • The closed-loop system achieves asymptotic voltage regulation under load and grid disturbances.
  • Strict energy dissipation is maintained without assuming constant grid voltage or frequency.
  • Simulations under realistic load changes and fault scenarios show smaller voltage deviations and faster recovery than cascaded proportional-integral controllers.
  • The approach is suitable for future high-efficiency DC data-center architectures that must tolerate variable conditions.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same energy-shaping structure could be adapted to converters interfacing variable renewable sources where input fluctuations replace grid disturbances.
  • Hardware validation on a scaled rack prototype would show whether the virtual damping term remains effective when sensor noise and switching delays are present.
  • Combining this controller with predictive load scheduling could further reduce peak energy deviations during sudden IT workload spikes.

Load-bearing premise

The converter must admit a Port-Hamiltonian formulation derived directly from its total energy balance so that energy shaping and interconnection can enforce passivity.

What would settle it

A test case in which voltage regulation diverges or energy fails to dissipate when grid frequency varies by more than a few hertz or when the load injects active power that violates the assumed passivity condition.

Figures

Figures reproduced from arXiv: 2605.21691 by Ella Chou, Fei Feng, Lizhi Wang, Yashen Lin.

Figure 1
Figure 1. Figure 1: DC data center power architecture. in [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: System normal operation performance. C. Closed-Loop Passivity and Grid Interaction Connecting ΣC with the PH plant through lossless ports yields the closed-loop storage Hcl = Hg + Hp + Hdc + HC, whose time derivative is H˙ cl = v ⊤ g ig − (Rg + Rf )∥if ∥ 2 − (1 − η)vdciconv − kv(vdc − v ⋆ dc) 2 − Ki∥ei∥ 2 . (27) The term v ⊤ g ig is the instantaneous power supplied by the grid, and all remaining terms are … view at source ↗
Figure 4
Figure 4. Figure 4: System performance with grid voltage sag rigorous foundation for stabilizing non-passive converter–load interactions and achieving resilient grid ride-through. Future work will extend this energy-structured design to large-scale, multi-converter DC architectures, investigate adaptive passiv￾ity rendering under parameter uncertainty, and experimentally validate the approach in hardware-in-the-loop and data-… view at source ↗
Figure 3
Figure 3. Figure 3: System performance with OCP load profile[2] C. System Performance with Grid Voltage Sag This scenario evaluates the resilience of the system under grid disturbances. A 20% grid voltage sag is applied from t=0.5 s. These conditions emulate typical power quality events in data-center distribution networks. During the disturbance, the PH-based controller maintains input-strict passivity: the total stored ener… view at source ↗
read the original abstract

This paper presents a passivity-based control framework for AC-DC converters supplying non-passive Information Technology rack loads in DC data centers. Unlike conventional cascaded proportional-integral controllers that ensure stability only near nominal operating points, the proposed method is derived from the system total energy balance using the Port-Hamiltonian formulation. By shaping the stored energy and injecting virtual damping through a lossless interconnection with a PH controller, the converter behaves as a passive system even when interfaced with non-passive loads or under grid disturbances. The closed-loop system guarantees asymptotic voltage regulation and strict energy dissipation without assuming constant grid voltage or frequency. Simulation studies under realistic load and fault scenarios validate that the proposed controller achieves smaller voltage deviations, faster recovery, and superior robustness, demonstrating its suitability for future high-efficiency DC data-center architectures.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 3 minor

Summary. The manuscript proposes a passivity-based control framework for AC-DC converters supplying non-passive IT rack loads in DC data centers. Derived from the system total energy balance via the Port-Hamiltonian formulation, the method shapes stored energy and injects virtual damping through a lossless interconnection with a PH controller. This is claimed to render the converter passive even with non-passive loads or grid disturbances, guaranteeing asymptotic voltage regulation and strict energy dissipation without assuming constant grid voltage or frequency. Superior performance over cascaded PI controllers is demonstrated via simulations under realistic load and fault scenarios.

Significance. If the theoretical guarantees hold, the work would advance resilient energy-based control for power electronics in data centers by providing global stability properties beyond local linearization. The derivation from total energy balance and simulation validation under realistic disturbances are strengths that could influence high-efficiency DC architectures. However, the central passivity claim under non-constant frequency requires explicit verification to realize this potential.

major comments (2)
  1. [Abstract and PH formulation section] Abstract and PH formulation section: The claim that the closed-loop system guarantees strict energy dissipation without assuming constant grid voltage or frequency is load-bearing for the contribution. The dq-frame transformation under time-varying grid frequency can introduce explicit time dependence, potentially adding non-skew-symmetric terms to the interconnection matrix and violating the conditions for the dissipation inequality to remain strict. The manuscript must show the explicit closed-loop PH equations (including any time-dependent terms) and prove that the storage function still satisfies the required inequality.
  2. [Simulation validation section] Simulation validation section: While realistic load and fault scenarios are considered, the absence of reported parameter values, error metrics, or sensitivity analysis to grid frequency variation rates makes it impossible to confirm that the observed smaller voltage deviations and faster recovery actually support the non-constant-frequency guarantee. This directly affects assessment of the central claim.
minor comments (3)
  1. [Abstract] Abstract: The phrase 'strict energy dissipation' should be tied explicitly to the damping matrix or dissipation function in the PH equations for clarity.
  2. [Notation and modeling] Notation: Define the storage function H and the virtual damping injection term at first use to avoid ambiguity in the energy-shaping step.
  3. [Introduction] References: Add citations to prior PH-based converter control works that handle time-varying frequency to better position the novelty.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive and detailed review of our manuscript. The comments correctly identify areas where additional explicit derivations and quantitative simulation details would strengthen the presentation of the passivity guarantees. We address each major comment below and indicate the revisions we will incorporate.

read point-by-point responses

  1. Referee: [Abstract and PH formulation section] Abstract and PH formulation section: The claim that the closed-loop system guarantees strict energy dissipation without assuming constant grid voltage or frequency is load-bearing for the contribution. The dq-frame transformation under time-varying grid frequency can introduce explicit time dependence, potentially adding non-skew-symmetric terms to the interconnection matrix and violating the conditions for the dissipation inequality to remain strict. The manuscript must show the explicit closed-loop PH equations (including any time-dependent terms) and prove that the storage function still satisfies the required inequality.

    Authors: We appreciate the referee's careful attention to the time-varying aspects of the dq transformation. In our Port-Hamiltonian derivation, the closed-loop interconnection matrix is constructed to remain skew-symmetric, with frequency variation terms appearing only in the energy-shaping component and not disrupting the required structure for the dissipation inequality. The virtual damping injection ensures strict passivity. To make this fully explicit as requested, we will revise the PH formulation section to display the complete closed-loop state equations, including all time-dependent terms, and add a dedicated proof (in the main text or appendix) showing that the storage function satisfies the strict dissipation inequality without requiring constant grid frequency. revision: yes

  2. Referee: [Simulation validation section] Simulation validation section: While realistic load and fault scenarios are considered, the absence of reported parameter values, error metrics, or sensitivity analysis to grid frequency variation rates makes it impossible to confirm that the observed smaller voltage deviations and faster recovery actually support the non-constant-frequency guarantee. This directly affects assessment of the central claim.

    Authors: We agree that the simulation results would be more convincing with additional quantitative information. In the revised manuscript we will add a table listing all converter, load, and controller parameters used in the studies, report explicit error metrics (maximum voltage deviation, settling time, and energy dissipation rate) for each scenario, and include a new sensitivity analysis that examines controller performance across a range of grid frequency variation rates. These additions will directly link the observed improvements to the non-constant-frequency passivity guarantee. revision: yes

Circularity Check

0 steps flagged

Derivation from total energy balance via Port-Hamiltonian formulation is self-contained

full rationale

The paper presents its passivity-based controller as derived directly from the system total energy balance using the Port-Hamiltonian formulation, with energy shaping and virtual damping introduced through a lossless interconnection. No equations or steps in the provided abstract or description reduce the central claims (asymptotic voltage regulation and strict dissipation under non-constant grid conditions) to fitted parameters, self-definitions, or load-bearing self-citations by construction. The guarantees follow from the mathematical structure of the closed-loop PH system rather than from renaming or predicting quantities already used as inputs. This is the most common honest finding for first-principles control derivations.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 1 invented entities

The central claim rests on the domain assumption that the system admits a Port-Hamiltonian energy-balance model allowing lossless interconnection and virtual damping to enforce passivity; no free parameters or new physical entities are explicitly introduced in the abstract.

axioms (1)
  • domain assumption The converter system can be modeled using the Port-Hamiltonian formulation derived from total energy balance.
    Invoked as the starting point for controller derivation and energy shaping in the abstract.
invented entities (1)
  • Virtual damping through lossless interconnection with PH controller no independent evidence
    purpose: To shape stored energy and enforce passive behavior with non-passive loads.
    Introduced as part of the control design to achieve the stated guarantees.

pith-pipeline@v0.9.0 · 5668 in / 1428 out tokens · 56180 ms · 2026-05-22T08:48:31.404806+00:00 · methodology

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Reference graph

Works this paper leans on

19 extracted references · 19 canonical work pages

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