Analysis and Control of Non-Minimum Phase Behavior in Nonlinear AC Grids Equipped with HVDC Links

Xing, Yankai; Aghababa, Mohammad Pourmahmood; Marinescu, Bogdan; Xavier, Florent

doi:10.1109/isgteurope.2019.8905703

Cited by 2 publications

(4 citation statements)

References 10 publications

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“…The existence of unstable zeros in the HVDC embedded system depends on the topology of the grids [26]. The effectiveness of POD can be decreased because of these unstable zeros [27].…”

Section: Unstable Zerosmentioning

confidence: 99%

VSC-HVDC Robust LMI Optimization Approaches to Improve Small-Signal and Transient Stability of Highly Interconnected AC grids

Xing¹,

Kamal²,

Marinescu³

et al. 2022

J. Engg. Res. & Sci.

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In this paper, for the situation of HVDC inserted in meshed AC power grid, a model-matching robust H ∞ static output error feedback controller (RSOFC) and model-matching dynamic decoupled output feedback controller (DDOFC) are proposed to improve the damping of inter-area oscillation modes and maintain robustness to face the effects of different operating points and unstable zeros. Sufficient conditions for robust stability are derived in the sense of Lyapunov asymptotic stability and presented in the form of linear matrix inequalities to obtain H ∞ RSOFC and DDOFC gains based on the reference model. The efficiency and robustness of the proposed controllers are tested and compared to Linear-Quadratic-Gaussian (LQG) control, mixed sensitivity H ∞ , standard (IEEE) Power Oscillation Damping (POD) controllers on a realistic benchmark of 19 generators connected by a meshed AC grid. The main contributions of this paper are: (i) Compensate the negative effect of unstable zeros (non-minimum phase behavior) on the performances of the closed-loop; (ii) the robustness is improved in order to provide good responses in case of network variations (load evolution, line, and generator trips, etc.) and HVDC line parameters changes; (iii) improve the damping compared with standard controller structures (LQG, mixed sensitivity H ∞ and standard POD controller).

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“…The existence of unstable zeros in the HVDC embedded system depends on the topology of the grids [26]. The effectiveness of POD can be decreased because of these unstable zeros [27].…”

Section: Unstable Zerosmentioning

confidence: 99%

VSC-HVDC Robust LMI Optimization Approaches to Improve Small-Signal and Transient Stability of Highly Interconnected AC grids

Xing¹,

Kamal²,

Marinescu³

et al. 2022

J. Engg. Res. & Sci.

Self Cite

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“…First, a benchmark was proposed in Reference 20 to take into account a large number of structures and oscillation paths in order to establish a link between the parameters of the benchmark and existence of open‐loop unstable zeros. Next, in Reference 7, a Modified Zero Phase Error Compensator (MZPEC) was proposed to cancel the negative effect of unstable zeros. The introduced MZPEC is free of the controller type applied, and it can be designed with the advanced POD controllers (ie, Linear Quadratic Gaussian [LQG] or

H_{\infty}

) to cancel unstable zeros to improve the dynamic responses.…”

Section: Power System Modeling and Problems Formulationmentioning

confidence: 99%

“…Unstable zeros in the system can bring some delays in the outputs of the system 6 . The appearance of unstable zeros in a AC grid model, which contains an HVDC link, has been analyzed in the former research 7 . In addition, plant models are usually subject to modeling errors and uncertainties.…”

Section: Introductionmentioning

confidence: 99%

“…6 The appearance of unstable zeros in a AC grid model, which contains an HVDC link, has been analyzed in the former research. 7 In addition, plant models are usually subject to modeling errors and uncertainties. In our case, these are due to variation of the grid operating point due to typical scenarios like, for example, generator and line trips, change of the amount of power transferred by the HVDC link, etc.…”

mentioning

confidence: 99%

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Advanced control to damp power oscillations with VSC‐HVDC links inserted in meshed AC grids

Xing

Kamal

Marinescu

et al. 2021

Int Trans Electr Energ Syst

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In this article, we consider the particular situation of a HVDC link inserted in a meshed AC grid, which has interarea modes at upper frequencies than the usual ones. In this case, the standard IEEE (lead-lag plus gain) controllers may not be efficient. As a matter of fact, in this grid situation, the control is challenged by unstable zeros and system uncertainties, systematically put into evidence. Two original robust strategies based on matching a reference model using LMI optimization approach are designed to provide coordinated active and reactive power modulation for the HVDC link. They are based on a reduced order control model of the HVDC and the neighboring AC zone, which integrates the dynamics of interest. Besides increased damping and diminished impact of the unstable zeros, this new control achieves robustness against grid variations. Investigations with both linearized and nonlinear model of the system are carried out to settle and validate the approach. The efficiency and robustness of the proposed controllers are tested and compared with the ones of several standard controllers on a realistic benchmark of 19 generators interconnected by a meshed AC grid.damping controller, HVDC, interarea modes, power system oscillations, robustness | INTRODUCTIONElectromechanical oscillations are a major concern of today power grids. This is a problem of power system oscillatory stability, as shown, for example, in Europe in December 2016 when low damping oscillations related to the most spread interarea mode (at 0.15 Hz) have been experienced. 1 When provided with supplementary damping control, the HVDCs have a good damping effect, which can be used to solve the problem of low-frequency oscillations between regions. Especially, voltage source converters (VSC)-HVDC transmission systems have the advantage to control both active and reactive power. This provides the opportunity to maintain system stability through supplementary power oscillations damping (POD) loops of control for both active and/or reactive power modulations. 2 The most analyzed and controlled in the past were the most spread interarea modes of the interconnected system, which are the ones in which are involved a large number of generators. They are at low frequencies, for example, around 0.2 Hz in Europe. Recent HVDC reinforcements in Europe (like France-Italy interconnection) are in the oscillation path of interarea modes of higher frequencies, around 1 Hz. There are also other dynamics of the grid in this frequency range (see References 3,4). These different dynamics should be taken into account more directly than in classic POD controllers (IEEE structures) and methodologies for gain computation (like, eg, Reference 5).

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Analysis and Control of Non-Minimum Phase Behavior in Nonlinear AC Grids Equipped with HVDC Links

Cited by 2 publications

References 10 publications

VSC-HVDC Robust LMI Optimization Approaches to Improve Small-Signal and Transient Stability of Highly Interconnected AC grids

VSC-HVDC Robust LMI Optimization Approaches to Improve Small-Signal and Transient Stability of Highly Interconnected AC grids

Advanced control to damp power oscillations with VSC‐HVDC links inserted in meshed AC grids

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