pith. sign in

arxiv: 1907.09589 · v1 · pith:VRT77OHYnew · submitted 2019-07-22 · 📡 eess.SY · cs.SY

Voltage Security Analysis of VSC-HVDC Transmission Lines

Chen Wang , Chetan Mishra This is my paper

Pith reviewed 2026-05-24 17:36 UTC · model grok-4.3

classification 📡 eess.SY cs.SY
keywords voltage securityVSC-HVDCP-V controlP-PF controlreactive load marginpower system stabilityHVDC control schemes
0
0 comments X

The pith

VSC-HVDC lines raise voltage security under P-V control but lower it under P-PF control.

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

The paper studies the effect of swapping 500 kV AC lines for VSC-HVDC lines on voltage security in a large utility planning model. It measures security through reactive load margins and compares two HVDC control modes across three zones picked by k-means clustering. P-V control increases the margins while P-PF control decreases them. The finding matters for grids that are retiring conventional plants and adding renewables, because the choice of HVDC control directly changes how close the system sits to voltage collapse.

Core claim

In the Dominion Energy model, replacement of AC lines by VSC-HVDC under P-V control increases reactive load margins and thereby improves voltage security; the same replacement under P-PF control decreases those margins and degrades voltage security. These outcomes appear consistently in the three representative zones examined.

What carries the argument

Reactive load margin method, which computes the additional reactive load the system can accept before voltage collapse, applied to P-V versus P-PF HVDC control schemes.

If this is right

  • Grid planners replacing AC lines with HVDC should select P-V control to enlarge voltage security margins.
  • P-PF control on new HVDC links can reduce the reactive support available before collapse.
  • Zone-specific analysis using clustering can locate where control choice has the largest security impact.

Where Pith is reading between the lines

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

  • The same control distinction may affect security under N-1 contingencies not tested in the paper.
  • Results could guide control tuning when multiple HVDC links interact in one area.

Load-bearing premise

The chosen Dominion Energy model, the k-means zone selection, and the exact P-V and P-PF implementations produce voltage-security results that hold for other systems and future conditions.

What would settle it

Direct measurement of reactive load margins on the real Dominion system after installing equivalent VSC-HVDC lines that show no improvement under P-V control or no degradation under P-PF control.

Figures

Figures reproduced from arXiv: 1907.09589 by Chen Wang, Chetan Mishra.

Figure 1
Figure 1. Figure 1: Typical Q-V Scatterplot in Dominion Peak Summer [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Typical QV Curve B. k-means Clustering K-means is a classical clustering algorithm used for unsupervised machine learning[13]. The basic idea is to iteratively assign data points into groups so that their ‘distances’ to their own fictitious group centers are minimized in general. In this paper, the k-means method is used to find groups of HVDC line cases that have similar impacts on reactive load margins o… view at source ↗
Figure 3
Figure 3. Figure 3: Q-margin percentage difference between AC case and P-V control HVDC case [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Q-margin percentage difference between AC case and P-PF control HVDC case [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Example case: Case A The middle figure shows the effect on generator reactive power output made by VSC-HVDC under P-PF control. From the figure we can see that with the P and Q fixed on the HVDC line, generators distributed in three zones cannot reach maximum reactive power output as reactive loads in zone 13 increases. So these loads have to be satisfied by local generators. This is the reason for Q-margi… view at source ↗
Figure 6
Figure 6. Figure 6: Example case: Case B In this case, zone 3 is supported by large generation locally. However, there is also large economic land resource available for renewable energy sources development, which could cause voltage fluctuations requiring better voltage controllability in the future. Considering P-PF control, voltage support from the far side of the HVDC line is significantly weakened. The Q-margin decrease … view at source ↗
Figure 7
Figure 7. Figure 7: Example case: Case C 5. CONCLUSION In this paper, the voltage security of Dominion system with selected AC lines upgraded to VSC-HVDC links is analyzed with reactive load margin. The simulation is run on PSS/E and the results are discussed. To sum up, the impact of replacing an AC line with an HVDC on voltage security can be understood in the following way. Take an example of a load area in the system conn… view at source ↗
read the original abstract

Due to generation retirements and growth of renewable energy sources integration, there will be widespread changes in the real and reactive power flow in nowadays power systems. These changes also bring about challenges on system operation and stability. High voltage direct current (HVDC) technology seems to be a promising solution to these new challenges. A study on the impact of the replacement of 500KV AC transmission lines by VSC-HVDC transmission line on system voltage security is conducted. The analysis is based on reactive load margin method and implemented on one of the Dominion Energy planning models. Different control schemes of HVDC are considered. Using k-means clustering method, three representative zones within the network are selected. The results corresponding to them are demonstrated and discussed. It is shown that HVDC lines with P-V control remarkably improve system voltage security, while those with P-PF control scheme have negative effects.

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

3 major / 1 minor

Summary. The manuscript studies the replacement of 500 kV AC lines by VSC-HVDC lines in a Dominion Energy planning model, using the reactive load margin method to assess voltage security. Three representative zones are identified via k-means clustering. Simulations compare P-V and P-PF control schemes for the HVDC terminals and conclude that P-V control improves voltage security while P-PF control degrades it.

Significance. If the sign of the control-mode effect on reactive load margin is shown to be robust, the result would be useful for transmission planners evaluating HVDC options under renewable integration and generation retirement scenarios. The work supplies no machine-checked proofs, parameter-free derivations, or cross-system replications.

major comments (3)
  1. [Abstract] Abstract: the headline claim that P-V control 'remarkably improve[s] system voltage security' while P-PF 'have negative effects' is presented without any reported numerical margins, confidence intervals, or sensitivity results, so the magnitude and reliability of the reported improvement cannot be assessed.
  2. [Case Study] Case Study section: all voltage-security outcomes are generated inside a single proprietary planning model with fixed HVDC siting and load distribution; no parameter sweeps, alternative topologies, or replication on a second system are supplied, leaving the central qualitative conclusion dependent on the untested assumption that the chosen model is representative.
  3. [Methodology] Methodology: the reactive load margin calculations treat HVDC terminal set-points and the precise implementation of P-V versus P-PF modes as free parameters, yet no values, coding details, or sensitivity to these choices are reported, making the sign of the reported effect non-reproducible from the given information.
minor comments (1)
  1. [Case Study] The features used for the k-means clustering step are not stated, preventing readers from reproducing the zone selection.

Simulated Author's Rebuttal

3 responses · 1 unresolved

We thank the referee for the detailed and constructive comments on our manuscript. We address each major comment below, indicating where revisions will be incorporated and where we maintain our position based on the scope of the study.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the headline claim that P-V control 'remarkably improve[s] system voltage security' while P-PF 'have negative effects' is presented without any reported numerical margins, confidence intervals, or sensitivity results, so the magnitude and reliability of the reported improvement cannot be assessed.

    Authors: We agree that the abstract would be strengthened by quantitative support. In the revised manuscript we will add explicit numerical values for the reactive load margins in the base case and the two HVDC control scenarios, together with the corresponding percentage changes, drawn directly from the case-study results already computed. revision: yes

  2. Referee: [Case Study] Case Study section: all voltage-security outcomes are generated inside a single proprietary planning model with fixed HVDC siting and load distribution; no parameter sweeps, alternative topologies, or replication on a second system are supplied, leaving the central qualitative conclusion dependent on the untested assumption that the chosen model is representative.

    Authors: The study deliberately uses a detailed, real-world planning model supplied by Dominion Energy that already incorporates the generation-retirement and renewable-integration conditions of interest. k-means clustering was applied precisely to extract representative zones within this model rather than relying on a single arbitrary location. While additional parameter sweeps or a second independent system would increase generality, such replications require access to other utilities' proprietary models and are outside the scope of the present work; the reported sign of the control-mode effect is therefore presented as a finding for this class of systems rather than a universal claim. revision: no

  3. Referee: [Methodology] Methodology: the reactive load margin calculations treat HVDC terminal set-points and the precise implementation of P-V versus P-PF modes as free parameters, yet no values, coding details, or sensitivity to these choices are reported, making the sign of the reported effect non-reproducible from the given information.

    Authors: We will expand the Methodology section to report the exact active- and reactive-power set-points employed at each HVDC terminal, the voltage-control limits used in P-V mode, and the power-factor target used in P-PF mode, together with a brief description of how these modes are realized inside the planning software. revision: yes

standing simulated objections not resolved
  • Replication of the study on a second, independent utility planning model, which would require proprietary data not available to the authors.

Circularity Check

0 steps flagged

No circularity; simulation outputs on proprietary model

full rationale

The paper reports numerical results from applying the reactive load margin method to a Dominion Energy planning model after replacing selected AC lines with VSC-HVDC under two control schemes (P-V and P-PF) and selecting zones via k-means. No derivation chain, equations, or first-principles claims are present that reduce to their own inputs by construction. The analysis is purely empirical/simulation-based; any limitations arise from model specificity and lack of generalization testing, not from self-referential definitions or fitted predictions masquerading as independent results.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The central claim rests on the validity of the proprietary planning model, the representativeness of three k-means zones, and the assumption that the two named control modes were implemented without additional tuning parameters.

free parameters (2)
  • number of k-means clusters
    k=3 chosen to define representative zones; value selected by authors.
  • HVDC terminal set-points
    Exact voltage or power-factor targets for each control mode not stated.
axioms (2)
  • domain assumption Reactive load margin computed from the planning model correctly quantifies voltage security.
    Standard industry metric invoked without re-derivation.
  • domain assumption The Dominion Energy planning model faithfully represents the real system under the studied contingencies.
    Model treated as ground truth for all reported margins.

pith-pipeline@v0.9.0 · 5674 in / 1367 out tokens · 37920 ms · 2026-05-24T17:36:22.365057+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

13 extracted references · 13 canonical work pages

  1. [1]

    Transient Stability Assessment (TSA) of Prone-to-Trip Renewable Generation (RG)-Rich Power Systems using Lyapunov's Direct Method

    Mishra, Chetan, Anamitra Pal, James S. Thorp, and Virgilio Antonio Centeno. "Transient Stability Assessment (TSA) of Prone-to-Trip Renewable Generation (RG)-Rich Power Systems using Lyapunov's Direct Method." IEEE Transactions on Sustainable Energy (2019)

    work page 2019

  2. [2]

    The black-out in southern Sweden and eastern Denmark, September 23, 2003

    Larsson, Sture, and A. Danell. "The black-out in southern Sweden and eastern Denmark, September 23, 2003." In Power Systems Conference and Exposition, 2006. PSCE'06. 2006 IEEE PES, pp. 309-313. IEEE, 2006

    work page 2003

  3. [3]

    Causes of the 2003 major grid blackouts in North America and Europe, and recommended means to improve system dynamic performance

    Andersson, Göran, Peter Donalek, Richard Farmer, Nikos Hatziargyriou, Innocent Kamwa, Prabhashankar Kundur, Nelson Martins et al. "Causes of the 2003 major grid blackouts in North America and Europe, and recommended means to improve system dynamic performance." IEEE Transactions on Power Systems 20, no. 4 (2005): 1922-1928

    work page 2003

  4. [4]

    VSC-HVDC application to improve the long-term voltage stability

    Tirtashi, M. Reza Safari, Jörgen Svensson, and Olof Samuelsson. "VSC-HVDC application to improve the long-term voltage stability." In PowerTech, 2017 IEEE Manchester, pp. 1-6. IEEE, 2017

    work page 2017

  5. [5]

    Singular value sensitivity based optimal control of embedded VSC-HVDC for steady-state voltage stability enhancement

    Urquidez, Omar A., and Le Xie. "Singular value sensitivity based optimal control of embedded VSC-HVDC for steady-state voltage stability enhancement." IEEE Transactions on Power Systems 31, no. 1 (2016): 216-225

    work page 2016

  6. [6]

    Improvement of voltage stability by using VSC-HVdc

    Latorre, Hector F., and M. Ghandhari. "Improvement of voltage stability by using VSC-HVdc." In Transmission & Distribution Conference & Exposition: Asia and Pacific, 2009, pp. 1-4. IEEE, 2009

    work page 2009

  7. [7]

    Influence of current limitation on voltage stability with voltage sourced converter HVDC

    Zeni, Lorenzo, Hjortur Johannsson, Anca D. Hansen, Poul E. Sorensen, Bo Hesselbaek, and Philip C. Kjaer. "Influence of current limitation on voltage stability with voltage sourced converter HVDC." In Innovative Smart Grid Technologies Europe (ISGT EUROPE), 2013 4th IEEE/PES, pp. 1-5. IEEE, 2013

    work page 2013

  8. [8]

    Design and return on investment analysis of residential solar photovoltaic systems

    Yang, Duotong, Haniph Latchman, Dave Tingling, and Anim Adrian Amarsingh. "Design and return on investment analysis of residential solar photovoltaic systems." IEEE Potentials 34, no. 4 (2015): 11-17

    work page 2015

  9. [9]

    A Study of Synchronous Breaker Switching With Preinsertion Resistor for Capacitors Banks

    Sun, Rui, Mark McVey, Duotong Yang, and James R. Stage. "A Study of Synchronous Breaker Switching With Preinsertion Resistor for Capacitors Banks." IEEE Transactions on Power Delivery 33, no. 2 (2017): 821-829

    work page 2017

  10. [10]

    Kalman-filter based recursive regression for three-phase line parameter estimation using synchrophasor measurements

    Mishra, Chetan, Virgilio A. Centeno, and Anamitra Pal. "Kalman-filter based recursive regression for three-phase line parameter estimation using synchrophasor measurements." In 2015 IEEE Power & Energy Society General Meeting, pp. 1-5. IEEE, 2015

    work page 2015

  11. [11]

    A voltage stability security assessment method

    Schlueter, R. A. "A voltage stability security assessment method." IEEE Transactions on Power Systems 13, no. 4 (1998): 1423-1438

    work page 1998

  12. [12]

    Powerworld.com. (2018). QV Curves. [online] Available at: https://www.powerworld.com/WebHelp/Content/MainDocumentation_HTML/QV_Curves.htm [Accessed 26 Jul. 2018]

    work page 2018

  13. [13]

    Constrained k-means clustering with background knowledge

    Wagstaff, Kiri, Claire Cardie, Seth Rogers, and Stefan Schrödl. "Constrained k-means clustering with background knowledge." In ICML, vol. 1, pp. 577-584. 2001

    work page 2001