## A generalized frame of reference for the incorporation of, multi-terminal VSC-HVDC systems in power flow solutions

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**A generalized frame of reference for the incorporation of, multi-terminal VSC-HVDC systems in power flow solutions.** / Acha, Enrique; Castro, Luis M.

Research output: Contribution to journal › Article › Scientific › peer-review

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*Electric Power Systems Research*, vol. 136, pp. 415-424. https://doi.org/10.1016/j.epsr.2016.03.009

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*Electric Power Systems Research*,

*136*, 415-424. https://doi.org/10.1016/j.epsr.2016.03.009

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TY - JOUR

T1 - A generalized frame of reference for the incorporation of, multi-terminal VSC-HVDC systems in power flow solutions

AU - Acha, Enrique

AU - Castro, Luis M.

PY - 2016/7/1

Y1 - 2016/7/1

N2 - This paper introduces a new and general frame-of-reference for true unified, iterative solutions of AC/DC power flows using the Newton-Raphson method. The emphasis is placed on the so-called multi-terminal VSC-HVDC systems. This frame-of-reference accommodates quite naturally any number of AC/DC sub-networks generated by an arbitrary number of VSC converters. Besides, each AC sub-network may contain any number of FACTS devices. The modeling approach adopted for the multi-terminal VSC-HVDC systems is incremental in nature. An AC system of arbitrary configuration is connected to the high-voltage side of the VSC's LTC transformer. In turn, the DC side of each pairing VSC is linked to a DC system of arbitrary configuration. The new model represents a paradigm shift in the way the fundamental frequency, positive sequence modeling of VSC-HVDC links are modeled, where the VSCs are not treated as idealized, controllable voltage sources but rather as compound transformer devices with which key control properties of the PWM-based converters are linked. In contrast to other contemporary approaches, the power flow iterative solutions carried out using the reference frame put forward in this paper exhibits a true quadratic convergence characteristic - in most credible cases, convergence to a tight power mismatch tolerance of e-12 would be achieved in five or less iterations.

AB - This paper introduces a new and general frame-of-reference for true unified, iterative solutions of AC/DC power flows using the Newton-Raphson method. The emphasis is placed on the so-called multi-terminal VSC-HVDC systems. This frame-of-reference accommodates quite naturally any number of AC/DC sub-networks generated by an arbitrary number of VSC converters. Besides, each AC sub-network may contain any number of FACTS devices. The modeling approach adopted for the multi-terminal VSC-HVDC systems is incremental in nature. An AC system of arbitrary configuration is connected to the high-voltage side of the VSC's LTC transformer. In turn, the DC side of each pairing VSC is linked to a DC system of arbitrary configuration. The new model represents a paradigm shift in the way the fundamental frequency, positive sequence modeling of VSC-HVDC links are modeled, where the VSCs are not treated as idealized, controllable voltage sources but rather as compound transformer devices with which key control properties of the PWM-based converters are linked. In contrast to other contemporary approaches, the power flow iterative solutions carried out using the reference frame put forward in this paper exhibits a true quadratic convergence characteristic - in most credible cases, convergence to a tight power mismatch tolerance of e-12 would be achieved in five or less iterations.

KW - MT-HVDC systems

KW - Newton-Raphson method

KW - Power flows

KW - VSC-HVDC modeling

U2 - 10.1016/j.epsr.2016.03.009

DO - 10.1016/j.epsr.2016.03.009

M3 - Article

VL - 136

SP - 415

EP - 424

JO - Electric Power Systems Research

JF - Electric Power Systems Research

SN - 0378-7796

ER -