A Smooth Power Flow Model of Electric Power System with Generator Reactive Power Limits Taken into Consideration

Kataoka, Yuki

doi:10.1109/iscas.2005.1465828

Cited by 7 publications

(5 citation statements)

References 5 publications

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“…Corrective models of SCOPF allow limited adjustment of operating points in response to contingencies, i.e., redispatch, in post-contingency scenarios [18]. In this case, to account for a realistic post-contingency behavior of generators, additional constraints have to be incorporated into corrective models of SCOPF formulation [19]. These additional constraints are based on nonsmooth, i.e., discontinuous, curves of real and reactive power responses to avoid prevent both active and reactive power violations [20].…”

Section: Introductionmentioning

confidence: 99%

“…Alternative differentiable power flow models using hyperbolic and sigmoid functions [19], patching functions with complementary homotopy methods [21], and discrete and continuous auxiliary variables, are discussed in [13]. In this paper, we introduce several continuously-differentiable models that respect high-fidelity physical models of generators considering an extensive list of contingency scenarios.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Modeling of Contingency Response in Security-constrained Optimal Power Flow

Altun¹,

Madani²,

Atamtürk³

et al. 2021

Preprint

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This paper provides an enhanced modeling of the contingency response that collectively reflects high-fidelity physical and operational characteristics of power grids. Integrating active and reactive power contingency responses into the securityconstrained optimal power flow (SCOPF) problem is challenging, due to the nonsmoothness and nonconvexity of feasible sets in consequence of piece-wise curves representing generator characteristics. We introduce a continuously-differentiable model using functions that closely resemble PV/PQ switching and the generator contingency response. These models enforce physical and operational limits by optimally allocating active power imbalances among available generators and deciding the bus type to switch from the PV type to the PQ type. The efficacy of this method is numerically validated on the IEEE 30-bus, 300bus, and 118-bus systems with 12, 10, and 100 contingencies, respectively.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced Modeling of Contingency Response in Security-constrained Optimal Power Flow

Altun¹,

Madani²,

Atamtürk³

et al. 2021

Preprint

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“…In order to find further insights with actual application to the general power flow problem, one needs to look into the related areas of Optimal Power Flow (OPF). Many authors have approached the problem of calculating maximum loadability in the presence of limits using OPF techniques [15], but it was specifically the representation of control limits by means of complementarity constraints [16,17,18] that triggered new approaches to the general power flow [19,20], most notably [21]. One key idea in these papers is the realization that a power flow with control limits can be tackled as a constrained optimization problem, even though its aim is not computing a loadability limit.…”

Section: Introductionmentioning

confidence: 99%

A Padé-Weierstrass technique for the rigorous enforcement of control limits in power flow studies

Trias¹,

Marín²

2018

International Journal of Electrical Power & Energy Systems

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A new technique is presented for solving the problem of enforcing control limits in power flow studies. As an added benefit, it greatly increases the achievable precision at nose points. The method is exemplified for the case of Mvar limits in generators regulating voltage on both local and remote buses. Based on the framework of the Holomorphic Embedding Loadflow Method (HELM), it provides a rigorous solution to this fundamental problem by framing it in terms of optimization. A novel Lagrangian formulation of power-flow, which is exact for lossless networks, leads to a natural physics-based minimization criterion that yields the correct solution. For networks with small losses, as is the case in transmission, the AC power flow problem cannot be framed exactly in terms of optimization, but the criterion still retains its ability to select the correct solution. This foundation then provides a way to design a HELM scheme to solve for the minimizing solution. Although the use of barrier functions evokes interior point optimization, this method, like HELM, is based on the analytic continuation of a germ (of a particular branch) of the algebraic curve representing the solutions of the system. In this case, since the constraint equations given by limits result in an unavoidable singularity at s = 1, direct analytic continuation by means of standard Padé approximation is fraught with numerical instabilities. This has been overcome by means of a new analytic continuation procedure, denominated Padé-Weierstrass, that exploits the covariant nature of the power flow equations under certain changes of variables. One colateral benefit of this procedure is that it can also be used when limits are not being enforced, in order to increase the achievable numerical precision in highly stressed cases.

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“…Uma ideia similar foi proposta em (Kataoka 2005), no entanto o método proposto apresenta diculdades de convergência e requer múltiplas soluções do método de Newton-Raphson para se obter a solução do caso sob estudo.…”

Section: Formulação Suaveunclassified

“…Nesse contexto, acredita-se que a formulação suave de limites aqui proposta, por não exibir nenhuma das desvantagens do método proposto em (Kataoka 2005 …”

Section: Formulação Suaveunclassified

Bifurcações induzidas por limites no contexto de estabilidade de tensão

Abrantes¹

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The interconnection of electric power systems (EPSs) led to an increase in security assessment complexity. Besides, due to economical and environmental inuences, EPSs have been operating closer to their transmission limits, which raises the relevance of security assessment in the context of voltage stability. In this scenario, problems related to EPS power transmission capacity, such as the limit induced bifurcation (LIB), become more important and bring the need of appropriate analysis tools.One of the goals of this project is to study the LIB problem more deeply, so it can be better understood in the context of voltage stability. Another objective is the development of methods for evaluating the load margin (LM) considering the possible occurrence of LIBs.Finally, since the LM sensitivity analysis due to saddle-node bifurcation (SNB) plays a highly important role in voltage stability studies, developing a method for LM sensitivity analysis due to LIB is our third objective.The sensitivity analysis is important not only because it provides information on the instability phenomenon and its mechanisms, but it is also useful for EPS security assessment, since it may provide knowledge on which control actions will be more eective in increasing the LM and which contingencies may be more severe. However, this analysis has been performed only for the case in which the LM is determined by a SNB point, not for the LIB case. With the intention of enabling pre-existing preventive control selection tools to treat the LIB phenomenon, a sensitivity analysis was performed at the LIB point similarly to what was developed for the SNB.Another contribution of this work is a smoothing formulation for complementary limits that was applied to the problem of limited reactive power injection of generating units. The proposed formulation transforms, at least numerically, the LIB in a SNB, which may be detected through methods already established in literature.

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A Smooth Power Flow Model of Electric Power System with Generator Reactive Power Limits Taken into Consideration

Cited by 7 publications

References 5 publications

Enhanced Modeling of Contingency Response in Security-constrained Optimal Power Flow

Enhanced Modeling of Contingency Response in Security-constrained Optimal Power Flow

A Padé-Weierstrass technique for the rigorous enforcement of control limits in power flow studies

Bifurcações induzidas por limites no contexto de estabilidade de tensão

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