scholarly journals Steady-State Stand-Alone Power Flow Solvers for Integrated Transmission-Distribution Networks: A Comparison Study and Numerical Assessment

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5784
Author(s):  
Maria Eliza Kootte ◽  
Cornelis Vuik
Keyword(s):  
Steady State ◽  
Power Systems ◽  
Power Flow ◽  
Large Scale ◽  
Energy Transition ◽  
Distribution Networks ◽  
Splitting Methods ◽  
Test Cases ◽  
Integrated Network ◽  
Three Phase

This paper compares and assesses several numerical methods that solve the steady-state power flow problem on integrated transmission-distribution networks. The integrated network model consists of a balanced transmission and an unbalanced distribution network. It is important to analyze these integrated electrical power systems due to the changes related to the energy transition. We classified the existing integration methods as unified and splitting methods. These methods can be applied to homogeneous (complete three-phase) and hybrid (single-phase/three-phase) network models, which results in four approaches in total. These approaches were compared on their accuracy and numerical performance—CPU time and number of iterations—to demonstrate their applicability on large-scale electricity networks. Furthermore, their sensitivity towards the amount of distributed generation and the addition of multiple distribution feeders was investigated. The methods were assessed by running power flow simulations using the Newton–Raphson method on several integrated power systems up to 25,000 unknowns. The assessment showed that unified methods applied to hybrid networks performed the best on these test cases. The splitting methods are advantageous when complete network data sharing between system operators is not allowed. The use of high-performance techniques for larger test cases containing multiple distribution networks will make the difference in speed less significant.

scholarly journals A modified backward/forward sweep-based method for reconfiguration of unbalanced distribution networks

2019 ◽  
Vol 9 (1) ◽  
pp. 85 ◽  
Author(s):  
Michel Duran-Quintero ◽  
John E. Candelo ◽  
Jose Soto-Ortiz
Keyword(s):  
Power Systems ◽  
Power Flow ◽  
Large Scale ◽  
Distribution Networks ◽  
Network Reconfiguration ◽  
Computational Tool ◽  
Topology Change ◽  
Flow Method ◽  
Three Phase ◽  
Power Flow Method

<span lang="EN-US">A three-phase unbalanced power flow method can provide a more realistic scenario of how distribution networks operate. The backward/forward sweep-based power flow method </span><span lang="EN-AU">(BF-PF)</span><span lang="EN-US"> has been used for many years as an important computational tool to solve the power flow for unbalanced and radial power systems. However, some of the </span><span lang="EN-AU">few </span><span lang="EN-US">available research tools produce many errors when </span><span lang="EN-AU">they </span><span lang="EN-US">are used for </span><span lang="EN-AU">network </span><span lang="EN-US">reconfiguration </span><span lang="EN-AU">because the </span><span lang="EN-US">topology change</span><span lang="EN-AU">s</span><span lang="EN-AU">after multiple switch actions</span><span lang="EN-US"> and the nodes are disorganized continually. </span><span lang="EN-AU">T</span><span lang="EN-US">his paper presents </span><span lang="EN-AU">a modified</span><span lang="EN-AU">BF-PF for </span><span lang="EN-US">three-phase unbalanced radial </span><span lang="EN-AU">distribution networks</span><span lang="EN-US"> that is capable </span><span lang="EN-AU">of arranging</span><span lang="EN-US"> the system topology when reconfiguration changes the branch connections. A binary search is used to determine the connections between nodes, allowing the algorithm to avoid those problems when reconfiguration is carried out, regardless of node numbers. Tests are made to verify the usefulness of the proposed algorithm in both the IEEE 13-node test feeder and the 123-node test feeder, converging in every run where constraints are accomplished. This approach can be used easily for a large-scale feeder network reconfiguration.</span><span lang="EN-AU"> The full version of this modified </span><span lang="EN-US">backward/forward sweep</span><span lang="EN-AU"> algorithm is available for research at MathWorks</span><span lang="EN-US">.</span>

scholarly journals Optimal Selection of Conductors in Three-Phase Distribution Networks Using a Discrete Version of the Vortex Search Algorithm

Computation ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 80
Author(s):  
John Fernando Martínez-Gil ◽  
Nicolas Alejandro Moyano-García ◽  
Oscar Danilo Montoya ◽  
Jorge Alexander Alarcon-Villamil
Keyword(s):  
Objective Function ◽  
Power Flow ◽  
Phase Distribution ◽  
Search Algorithm ◽  
Distribution Networks ◽  
Discrete Version ◽  
Optimal Selection ◽  
Flow Method ◽  
Three Phase ◽  
Selection Of

In this study, a new methodology is proposed to perform optimal selection of conductors in three-phase distribution networks through a discrete version of the metaheuristic method of vortex search. To represent the problem, a single-objective mathematical model with a mixed-integer nonlinear programming (MINLP) structure is used. As an objective function, minimization of the investment costs in conductors together with the technical losses of the network for a study period of one year is considered. Additionally, the model will be implemented in balanced and unbalanced test systems and with variations in the connection of their loads, i.e., Δ− and Y−connections. To evaluate the costs of the energy losses, a classical backward/forward three-phase power-flow method is implemented. Two test systems used in the specialized literature were employed, which comprise 8 and 27 nodes with radial structures in medium voltage levels. All computational implementations were developed in the MATLAB programming environment, and all results were evaluated in DigSILENT software to verify the effectiveness and the proposed three-phase unbalanced power-flow method. Comparative analyses with classical and Chu & Beasley genetic algorithms, tabu search algorithm, and exact MINLP approaches demonstrate the efficiency of the proposed optimization approach regarding the final value of the objective function.

scholarly journals A Full-Newton AC-DC Power Flow Methodology for HVDC Multi-Terminal Systems and Generic DC Network Representation

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1658
Author(s):  
Leandro Almeida Vasconcelos ◽  
João Alberto Passos Filho ◽  
André Luis Marques Marcato ◽  
Giovani Santiago Junqueira
Keyword(s):  
Power Systems ◽  
Direct Current ◽  
Power Flow ◽  
Large Scale ◽  
Flow Problem ◽  
Control Strategies ◽  
Problem Formulation ◽  
Expansion Planning ◽  
Dc Power ◽  
Power Flow Problem

The use of Direct Current (DC) transmission links in power systems is increasing continuously. Thus, it is important to develop new techniques to model the inclusion of these devices in network analysis, in order to allow studies of the operation and expansion planning of large-scale electric power systems. In this context, the main objective of this paper is to present a new methodology for a simultaneous AC-DC power flow for a multi-terminal High Voltage Direct Current (HVDC) system with a generic representation of the DC network. The proposed methodology is based on a full Newton formulation for solving the AC-DC power flow problem. Equations representing the converters and steady-state control strategies are included in a power flow problem formulation, resulting in an expanded Jacobian matrix of the Newton method. Some results are presented based on HVDC test systems to confirm the effectiveness of the proposed approach.

scholarly journals Accurate and Efficient Derivative-Free Three-Phase Power Flow Method for Unbalanced Distribution Networks

Computation ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 61
Author(s):  
Oscar Danilo Montoya ◽  
Juan S. Giraldo ◽  
Luis Fernando Grisales-Noreña ◽  
Harold R. Chamorro ◽  
Lazaro Alvarado-Barrios
Keyword(s):  
Power Flow ◽  
Triangular Matrix ◽  
Distribution Networks ◽  
Flow Method ◽  
Processing Times ◽  
Three Phase ◽  
Derivative Free ◽  
Upper Triangular Matrix ◽  
Power Flow Problem ◽  
Power Flow Method

The power flow problem in three-phase unbalanced distribution networks is addressed in this research using a derivative-free numerical method based on the upper-triangular matrix. The upper-triangular matrix is obtained from the topological connection among nodes of the network (i.e., through a graph-based method). The main advantage of the proposed three-phase power flow method is the possibility of working with single-, two-, and three-phase loads, including Δ- and Y-connections. The Banach fixed-point theorem for loads with Y-connection helps ensure the convergence of the upper-triangular power flow method based an impedance-like equivalent matrix. Numerical results in three-phase systems with 8, 25, and 37 nodes demonstrate the effectiveness and computational efficiency of the proposed three-phase power flow formulation compared to the classical three-phase backward/forward method and the implementation of the power flow problem in the DigSILENT software. Comparisons with the backward/forward method demonstrate that the proposed approach is 47.01%, 47.98%, and 36.96% faster in terms of processing times by employing the same number of iterations as when evaluated in the 8-, 25-, and 37-bus systems, respectively. An application of the Chu-Beasley genetic algorithm using a leader–follower optimization approach is applied to the phase-balancing problem utilizing the proposed power flow in the follower stage. Numerical results present optimal solutions with processing times lower than 5 s, which confirms its applicability in large-scale optimization problems employing embedding master–slave optimization structures.

scholarly journals Predicting AC Optimal Power Flows: Combining Deep Learning and Lagrangian Dual Methods

2020 ◽  
Vol 34 (01) ◽  
pp. 630-637 ◽  
Author(s):  
Ferdinando Fioretto ◽  
Terrence W.K. Mak ◽  
Pascal Van Hentenryck
Keyword(s):  
Deep Learning ◽  
Power Systems ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Large Scale ◽  
Renewable Energy Sources ◽  
Electrical Power ◽  
Practical Applications ◽  
Fundamental Building Block ◽  
Optimal Power

The Optimal Power Flow (OPF) problem is a fundamental building block for the optimization of electrical power systems. It is nonlinear and nonconvex and computes the generator setpoints for power and voltage, given a set of load demands. It is often solved repeatedly under various conditions, either in real-time or in large-scale studies. This need is further exacerbated by the increasing stochasticity of power systems due to renewable energy sources in front and behind the meter. To address these challenges, this paper presents a deep learning approach to the OPF. The learning model exploits the information available in the similar states of the system (which is commonly available in practical applications), as well as a dual Lagrangian method to satisfy the physical and engineering constraints present in the OPF. The proposed model is evaluated on a large collection of realistic medium-sized power systems. The experimental results show that its predictions are highly accurate with average errors as low as 0.2%. Additionally, the proposed approach is shown to improve the accuracy of the widely adopted linear DC approximation by at least two orders of magnitude.

Power Flow Calculation Realization in Software for Grids with Four-Phase Power Lines

2014 ◽  
Vol 698 ◽  
pp. 694-698 ◽  
Author(s):  
Dmitry I. Bliznyuk ◽  
Pavel Y. Bannykh ◽  
Alexandra I. Khalyasmaa
Keyword(s):  
Steady State ◽  
Power Flow ◽  
Calculation Model ◽  
Power Lines ◽  
Power Flow Calculation ◽  
Steady State Analysis ◽  
Flow Calculation ◽  
Analysis Methods ◽  
Electrical Grids ◽  
Three Phase

The paper is devoted to the problem of power flow calculation and steady state analysis methods adaptation for four-phase electrical grids. These methods are based on developed models of four-phase power lines and phase convering transformers. The basis of research is nodal voltages equations for three-phase, four-phase and mixed (combined by three-and four-phase elements) grids. Algorithm of four-phfase elements parameters automized adaptation for power flow calculation model of "RastrWin" software have been developed.

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