Loop flows in a ring AC power system

Janssens, N.; Kamagate, Amadou

doi:10.1016/s0142-0615(03)00017-6

Cited by 20 publications

(19 citation statements)

References 2 publications

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“…and they have two subcategories: fixed technical losses and variable technical losses [22]. While fixed technical losses are purely related to material characteristics of the component and do not change with the possible variations of the current passing by, variable technical losses are current-dependent.…”

Section: Non -Technical Lossesmentioning

confidence: 99%

The effect of the types of network topologies on non-technical losses in secondary electric distribution systems

Yorukoglu

Nasibov

Mungan

et al. 2016

2016 IEEE/IAS 52nd Industrial and Commercial Power Systems Technical Conference (I&CPS)

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A portion of generated electrical power is lost in transmission and distribution systems while serviced to endusers. These losses are called technical and non-technical losses in electricity distributions systems. With privatization processes taken place over the world, huge debate arose regarding nontechnical losses. In this study, information about types of losses in distribution systems, privatization process in Turkish electricity distribution network and current loss percentages are given. Possible alterations in distribution network topology to decrease non-technical losses are examined using analytical methods. Best methodology against non-technical losses is determined for different network topologies and customer characteristics, using AHP method. Choosing a pilot network, in which losses are considerably high, a case study is conducted. Cost-benefit analysis is performed within the scope of case study. Results of the case study indicate substantial potential for reducing non-technical losses by just altering network topology, where 1.6% reduction in overall T&L rates is estimated.

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Section: Non -Technical Lossesmentioning

confidence: 99%

The effect of the types of network topologies on non-technical losses in secondary electric distribution systems

Yorukoglu

Nasibov

Mungan

et al. 2016

2016 IEEE/IAS 52nd Industrial and Commercial Power Systems Technical Conference (I&CPS)

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“…The two main purposes of this manuscript are therefore (i) to investigate how vortex flows can be created in electric power grids and (ii) to investigate how resilient they are to the presence of ohmic dissipation. Our investigations of creation mechanisms amplify on the work of Janssens and Kamagate [14] who succinctly discussed one of the three mechanisms we identify below. Investigating basins of stability for different solutions via the Lyapunov function allows us furthermore to shed analytical light on the line reclosing mechanism they proposed [14] and give precise bounds on when vortex flows are created in this way.…”

Section: Introductionmentioning

confidence: 96%

“…Our investigations of creation mechanisms amplify on the work of Janssens and Kamagate [14] who succinctly discussed one of the three mechanisms we identify below. Investigating basins of stability for different solutions via the Lyapunov function allows us furthermore to shed analytical light on the line reclosing mechanism they proposed [14] and give precise bounds on when vortex flows are created in this way. We furthermore find that vortex flows are resilient to reasonable amounts of ohmic dissipation typical of high voltage power grids and that vortex-carrying operating states ohmically dissipate significantly more electric power than vortex-free states.…”

Section: Introductionmentioning

confidence: 96%

“…Tavora and Smith related the existence of different stable fixed points of the power flow problem to the presence of integer winding numbers [16], reflecting the 2p-periodicity of the complex voltage around any loop in the network and its single-valuedness. The characterization of circulating loop flows with topological winding numbers has been pushed further by Janssens and Kamagate [14], who also investigated how to generate such loop flows and found one of the three creation mechanisms we discuss below. More recently, [9,10] showed that within the lossless line approximation, different power flow solutions must be related to one another by circulating loop flows.…”

Section: Introductionmentioning

confidence: 99%

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Topologically protected loop flows in high voltage AC power grids

et al. 2016

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Geographical features such as mountain ranges or big lakes and inland seas often result in large closed loops in high voltage AC power grids. Sizable circulating power flows have been recorded around such loops, which take up transmission line capacity and dissipate but do not deliver electric power. Power flows in high voltage AC transmission grids are dominantly governed by voltage angle differences between connected buses, much in the same way as Josephson currents depend on phase differences between tunnel-coupled superconductors. From this previously overlooked similarity we argue here that circulating power flows in AC power grids are analogous to supercurrents flowing in superconducting rings and in rings of Josephson junctions. We investigate how circulating power flows can be created and how they behave in the presence of ohmic dissipation. We show how changing operating conditions may generate them, how significantly more power is ohmically dissipated in their presence and how they are topologically protected, even in the presence of dissipation, so that they persist when operating conditions are returned to their original values. We identify three mechanisms for creating circulating power flows, (i) by loss of stability of the equilibrium state carrying no circulating loop flow, (ii) by tripping of a line traversing a large loop in the network and (iii) by reclosing a loop that tripped or was open earlier. Because voltages are uniquely defined, circulating power flows can take on only discrete values, much in the same way as circulation around vortices is quantized in superfluids.

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“…This latter observation eventually led to the characterization of circulating loop flows with discrete topological winding numbers. 6,16,26,27 Using winding numbers, Rogge and Aeyels 12 obtained an algebraic upper bound N ≤ 2 · Int[n/4] + 1 for the number of stable fixed point solutions with any angle difference in a Kuramoto model on a n-node ring with unidirectional nearest-neighbor couplings. The same upper bound has been calculated by Ochab and Góra 28 in a nonoriented n-node Kuramoto ring with nearest-neighbor coupling, under the condition that all angle differences are smaller than π/2.…”

Section: Introductionmentioning

confidence: 99%

Multistability of phase-locking in equal-frequency Kuramoto models on planar graphs

Delabays

Coletta

Jacquod

2017

Journal of Mathematical Physics

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The number N of stable fixed points of locally coupled Kuramoto models depends on the topology of the network on which the model is defined. It has been shown that cycles in meshed networks play a crucial role in determining N , because any two different stable fixed points differ by a collection of loop flows on those cycles. Since the number of different loop flows increases with the length of the cycle that carries them, one expects N to be larger in meshed networks with longer cycles. Simultaneously, the existence of more cycles in a network means more freedom to choose the location of loop flows differentiating between two stable fixed points. Therefore, N should also be larger in networks with more cycles. We derive an algebraic upper bound for the number of stable fixed points of the Kuramoto model with identical frequencies, under the assumption that angle differences between connected nodes do not exceed π/2. We obtain N ≤ c k=1 [2 · Int(n k /4) + 1], which depends both on the number c of cycles and on the spectrum of their lengths {n k }. We further identify network topologies carrying stable fixed points with angle differences larger than π/2, which leads us to conjecture an upper bound for the number of stable fixed points for Kuramoto models on any planar network. Compared to earlier approaches that give exponential upper bounds in the total number of vertices, our bounds are much lower and therefore much closer to the true number of stable fixed points.

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Loop flows in a ring AC power system

Cited by 20 publications

References 2 publications

The effect of the types of network topologies on non-technical losses in secondary electric distribution systems

The effect of the types of network topologies on non-technical losses in secondary electric distribution systems

Topologically protected loop flows in high voltage AC power grids

Multistability of phase-locking in equal-frequency Kuramoto models on planar graphs

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