Impact of power factor regulation on small‐signal stability of power distribution systems with distributed synchronous generators

2013 IEEE Grenoble Conference

Geraldi

Ramos

2013

The increase of distributed generation in the global scenario has motivated the study of the electromechanical oscillation phenomenon in distribution systems with load imbalance, an intrinsic characteristic of this type of system. In this paper, after showing that typical linearization procedures cannot be applied to the assessment of the small-signal stability of unbalanced distributed generation systems, this assessment is done with the application of a modal estimation technique: the Prony method. This approach enables the calculation of oscillation frequencies and damping ratios under unbalanced conditions, as earlier works from the authors have shown. However, under realistic conditions, measurement noise patterns with different spectra may degrade the results of the proposed application. The main contribution of this paper is the evaluation of the impact of noise over the small-signal stability assessment technique proposed by the authors for unbalanced distribution generation systems, aiming at a better suited technique for practical applications. The results show that, while frequency remains mostly unaffected by the presence of noise, the identification of the damping ratio can be significantly influenced by this factor.

Section: A Study Systemmentioning

confidence: 99%

Section: A Study Systemmentioning

confidence: 99%

See 1 more Smart Citation

Application of modal estimation techniques for small signal stability assessment in distribution systems considering measurement noise

2013 IEEE Grenoble Conference

Geraldi

Ramos

2013

“…To do so, the loads admittances are calculated by (3), where the steady-state voltage magnitudes are assumed to be equal to 1p.u.. In Step 2, the TSC-OPF is formulated by using a sufficient number of numerical integration steps in pre-fault and fault-on periods and three numerical integration steps in post-fault period, which is enough to check the existence or not of a first peak angle after the elimination of the disturbance.…”

Section: The Proposed Algorithmmentioning

confidence: 99%

Optimal operation of distribution networks with synchronous generators via transient stability constrained optimal power flow

Fuchs

Kuiava

2015 IEEE Power &Amp; Energy Society General Meeting

2015

A common approach to deal with transient stability constraints in optimization problems is the combination of a numerical discretization method with interior point methods (IPMs) for solving large-scale nonlinear programming (NLP). The numerical discretization is adopted to convert the differential equations that describe the electromechanical transients in power systems in a set of algebraic equations to be included into a conventional optimal power flow (OPF) problem. The resulting transient stability constrained optimal power flow (TSC-OPF) problem, however, suffers with the curse of dimensionality, high computational time and memory consumption to solve it, even for small systems. To relieve this computational burden, this paper proposes an algorithm that aims at solving a TSC-OPF problem via primal-dual IPM with only a few time steps of numerical discretization in post-fault period, which is enough to ensure the rotor angle first swing stability. Once the TSC-OPF problem is solved, a numerical discretization method is applied to calculate the system trajectory from the first rotor angle peak in post-fault period. An important contribution of the proposed algorithm is to provide a proper accuracy on the computation of constant admittance loads. Numerical results are obtained for a 9-bus distribution network with the purpose of providing a proper sizing of DG units based on synchronous generators and an optimal operation to the network.

“…These oscillations, when poorly damped, are detrimental for the system operation and performance, and in some cases may affect the power quality of the system. In the context of power quality, voltage fluctuation is the main phenomenon observed in distribution systems with distributed synchronous generators [6]- [8].…”

Section: Introductionmentioning

confidence: 99%

Application of extended participation factors to detect voltage fluctuations in distributed generation systems

Ramos

Moraco

2011 IEEE Power and Energy Society General Meeting

et al. 2011

Self Cite

The dynamics of distribution systems has been significantly modified by the increasing penetration of distributed generation in distribution grids. Distribution systems, with distributed synchronous generators, may exhibit dynamic characteristics similar to those observed in transmission systems, such as, for example, low-frequency electromechanical oscillations. The impacts related to electromechanical oscillations raise important concerns about the system stability and power quality across the distribution grids. Tools usually employed to analyze such kind of oscillations in transmission systems (such as participation factors, for example), may not be fully appropriate for analyzing this same phenomenon in distribution systems. Due to the aforementioned issues, this work proposes the use of extended participation factors as a tool to detect voltage fluctuations caused by electromechanical oscillations in distributed generation systems. The results of a case study show that, in some cases, the traditional participation factors are not able to detect these fluctuations, while the extended participation factors performed well with respect to this detection.