A general-purpose version of the fast decoupled load flow
TL;DR: In this article, a new version of the fast decoupled load flow, in which a more broad range of power systems can be solved, is presented, and the key lies in the different way in which the resistances are ignored and in a different iteration scheme.
Abstract: A new version of the fast decoupled load flow, in which a more broad range of power systems can be solved, is presented. The key lies in the different way in which the resistances are ignored and in a different iteration scheme. In the standard algorithm the resistances are ignored while building the B' load flow matrix: it is shown that it is preferable that the resistances are ignored in the B" matrix instead of the B' matrix. For normal test systems there is hardly any difference in the number of iterations. However, the new algorithm iterates faster if one or more problematic R/X ratios are present. An iteration scheme with strict successive P and Q iterations prevents cycling convergence behavior which can be found in some low voltage systems. The advantages of the new version are demonstrated with runs on IEEE test systems, with both uniformly and nonuniformly scaled reactances. R-scaling up to 3 is always possible, and sometimes values up to 5 can be used. X-scaling of at least 0.1 is possible without losing convergence and with iteration counts which are significantly lower than with the standard scheme. >
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TL;DR: The details of the network modeling and problem formulations used by MATPOWER, including its extensible OPF architecture, are presented, which are used internally to implement several extensions to the standard OPF problem, including piece-wise linear cost functions, dispatchable loads, generator capability curves, and branch angle difference limits.
Abstract: MATPOWER is an open-source Matlab-based power system simulation package that provides a high-level set of power flow, optimal power flow (OPF), and other tools targeted toward researchers, educators, and students. The OPF architecture is designed to be extensible, making it easy to add user-defined variables, costs, and constraints to the standard OPF problem. This paper presents the details of the network modeling and problem formulations used by MATPOWER, including its extensible OPF architecture. This structure is used internally to implement several extensions to the standard OPF problem, including piece-wise linear cost functions, dispatchable loads, generator capability curves, and branch angle difference limits. Simulation results are presented for a number of test cases comparing the performance of several available OPF solvers and demonstrating MATPOWER's ability to solve large-scale AC and DC OPF problems.
5,583 citations
Cites methods from "A general-purpose version of the fa..."
...Also included are solvers based on variations of the fastdecoupled method [8], specifically, the XB and BX methods described in [9]....
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TL;DR: Basic features, algorithms, and a variety of case studies are presented in this paper to illustrate the capabilities of the presented tool and its suitability for educational and research purposes.
Abstract: This paper describes the Power System Analysis Toolbox (PSAT), an open source Matlab and GNU/Octave-based software package for analysis and design of small to medium size electric power systems. PSAT includes power flow, continuation power flow, optimal power flow, small-signal stability analysis, and time-domain simulation, as well as several static and dynamic models, including nonconventional loads, synchronous and asynchronous machines, regulators, and FACTS. PSAT is also provided with a complete set of user-friendly graphical interfaces and a Simulink-based editor of one-line network diagrams. Basic features, algorithms, and a variety of case studies are presented in this paper to illustrate the capabilities of the presented tool and its suitability for educational and research purposes.
890 citations
Cites methods from "A general-purpose version of the fa..."
...PSAT included the standard Newton-Raphson method [15], the fast decoupled power flow (XB and BX variations [16]), and a power flow with a distributed slack bus model [17]....
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Book•
31 Mar 2019TL;DR: This monograph provides the first comprehensive survey of representations in the context of optimization of the power flow equations, categorized as either relaxations or approximations.
Abstract: The power flow equations model the relationship between voltage phasors and power injections at nodes (buses) in an electric power system and are fundamental in their analysis and operation. A wealth of literature exists on these equations, many providing different representations of them. This monograph provides the first comprehensive survey of representations in the context of optimization. To achieve this the power flow representations surveyed are categorized as either relaxations or approximations. The techniques described in here form the basis of running an optimally efficient modern day power system. A Survey of Relaxations and Approximations of the Power Flow Equations is a must-read for all students and researchers working on the cutting edge of electric power systems.
258 citations
Book•
08 Oct 2008
TL;DR: Stochastic Security Analysis of Electrical Power Systems and Power System Transient Stability Analysis and Small-Signal Stability Analysis of Power Systems.
Abstract: Mathematical Model and Solution of Electric Network.- Load Flow Analysis.- Stochastic Security Analysis of Electrical Power Systems.- Power Flow Analysis in Market Environment.- HVDC and FACTS.- Mathematical Model of Synchronous Generator and Load.- Power System Transient Stability Analysis.- Small-Signal Stability Analysis of Power Systems.
248 citations
Cites methods from "A general-purpose version of the fa..."
...The authors of [9, 10] explain the implications of the simplifications made in the fast decoupled method....
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...Many contributions seek to improve the convergence characteristics of the Newton method and the P Q decoupled method [9–15]....
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...The basic idea of the fast decoupled method is expressing the nodal power as a function of voltages in polar form; separately solving the active and reactive power equations [9] by using active power mismatch to modify voltage angle and using reactive power mismatch to modify voltage magnitude....
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TL;DR: In this article, the effects of a high level of grid connected photovoltaic (PV) in the middle voltage distribution network have been analyzed and the emphasis is put on static phenomena, including voltage drop, network losses and grid benefits.
244 citations
Cites methods from "A general-purpose version of the fa..."
...This traditional Newton-Raphson method was chosen due to its simplicity, although faster decoupled power flow method exists [13,14]....
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References
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TL;DR: This paper describes a simple, very reliable and extremely fast load-flow solution method that is attractive for accurate or approximate off-and on-line routine and contingency calculations for networks of any size, and can be implemented efficiently on computers with restrictive core-store capacities.
Abstract: This paper describes a simple, very reliable and extremely fast load-flow solution method with a wide range of practical application. It is attractive for accurate or approximate off-and on-line routine and contingency calculations for networks of any size, and can be implemented efficiently on computers with restrictive core-store capacities. The method is a development on other recent work employing the MW-?/ MVAR-V decoupling principle, and its precise algorithmic form has been determined by extensive numerical studies. The paper gives details of the method's performance on a series of practical problems of up to 1080 buses. A solution to within 0.01 MW/MVAR maximum bus mismatches is normally obtained in 4 to 7 iterations, each iteration being equal in speed to 1? Gauss-Seidel iterations or 1/5th of a Newton iteration. Correlations of general interest between the power-mismatch convergence criterion and actual solution accuracy are obtained.
1,447 citations
TL;DR: The ac power flow problem can be solved efficiently by Newton's method because only five iterations, each equivalent to about seven of the widely used Gauss-Seidel method are required for an exact solution.
Abstract: The ac power flow problem can be solved efficiently by Newton's method. Only five iterations, each equivalent to about seven of the widely used Gauss-Seidel method, are required for an exact solution. Problem dependent memory and time requirements vary approximately in direct proportion to problem size. Problems of 500 to 1000 nodes can be solved on computers with 32K core memory. The method, introduced in 1961, has been made practical by optimally ordered Gaussian elimination and special programming techniques. Equations, programming details, and examples of solutions of large problems are given.
1,112 citations
01 Jul 1974
TL;DR: A survey is presented on the currently available numerical techniques for power-system load-flow calculation using the digital computer, and the suitabilities of various methods for modern applications such as security monitoring and optimal load flow are examined.
Abstract: A survey is presented on the currently available numerical techniques for power-system load-flow calculation using the digital computer. The review deals with methods that have received widespread practical application, recent attractive developments, and other methods that have interesting or useful characteristics. The analytical bases, computational requirements, and comparative numerical performances of the methods are discussed. Attention is given to the problems and techniques of adjustments in load-flow solutions, and the suitabilities of various methods for modern applications such as security monitoring and optimal load flow are examined.
696 citations
TL;DR: In this paper, a modification of the fast decoupled load-flow method for power systems with high ratio of branch resistance to reactance has been presented, and the test results show that this method not only converges well for systems with very high branch resistance, but also is only slightly less efficient than systems with normal ratios.
Abstract: The reliability of the fast decoupled load-flow method for most power systems is high, but it presents difficulties in convergence for systems with high ratios of branch resistance to reactance. Modifications that retain the advantages of this method but can handle high r/x ratios are of interest, and compensation techniques have been used for this purpose. Both the series and parallel compensation techniques, however, give mixed results. A modification is presented that performed better on several test systems. The test results show that this method not only converges well for systems with high r/x ratios but also is only slightly less efficient than the fast decoupled method for systems with normal ratios. >
141 citations
TL;DR: In this paper, twenty one different versions of four topological load-flow equivalencing approaches have been tested on a number of power systems and the results of the tests provide a strong guide to the choice of specific equivalents for practical on-and off-line applications.
Abstract: Twenty one different versions of four topological load-flow equivalencing approaches have been tested on a number of power systems. From these tests, it has been possible to ascribe some general properties, in terms of accuracy and conditioning, to the equivalents. Several new and very competitive versions were developed during the work, and are presented here. The results of the tests provide a strong guide to the choice of specific equivalents for practical on- and off-line applications.
127 citations