A solution to the single-snapshot non-linear L-1 estimation of the power transmission network is presented. The non-linear L-1 estimation problem is formulated as a non-linear program and solved using a primal-dual in...
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A solution to the single-snapshot non-linear L-1 estimation of the power transmission network is presented. The non-linear L-1 estimation problem is formulated as a non-linear program and solved using a primal-dual interior-point approach. The efficiency of this approach is dependent on the numerical procedure used to solve the reduced Karush-Kuhn-Tucker (KKT) system of equations. It is shown that two mathematically equivalent formulations of the non-linear programmingproblem can be obtained. These formulations lend themselves to fundamentally different numerical procedures to solve the reduced KKT system. Numerical testing on IEEE systems is used to quantify the performance of the interior-point approach on both formulations. Comparisons are also carried out with a recent implementation of an iteratively reweighted least-squares method for non-linear L-1 regression.
A new and comprehensive method for optimal reactive power planning (ORPP) against voltage collapse (VC) is given. The problem has the objectives of optimally siting and sizing new capacitors at prospective locations s...
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A new and comprehensive method for optimal reactive power planning (ORPP) against voltage collapse (VC) is given. The problem has the objectives of optimally siting and sizing new capacitors at prospective locations such that the transmission loss is minimum, an acceptable voltage profile is obtained, and the voltage stability is improved. To plan against VC, modal analysis is used to generate a participation-factor-based voltage collapse sensitive index (VCSI). VCSI is used to rank and select the best few prospective buses to site new capacitors. Using fuzzy models, all the violated load bus voltage constraints are fuzzified and their enforcements are maximised. The nonlinear programming problem of ORPP is solved in the successive multiobjective fuzzy LP framework. The proposed method was tested on modified IEEE 6-bus system and on a 191-bus Indian electric utility system. The results of the studies are discussed.
In this work, we present a simple framework to synthesize human motion. Our main goal is to propose a methodology tailored for inexperienced users to initiate their research in human motion simulation and human motion...
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In this work, we present a simple framework to synthesize human motion. Our main goal is to propose a methodology tailored for inexperienced users to initiate their research in human motion simulation and human motion trajectory optimization. The novelties of the work include the following. First, trigonometric splines are used instead of traditional B-splines to discretize the generalized coordinates and velocities. Second, useful identities for trigonometric splines are derived. Third, this work is intended to be an example, so that even non-skilled users, such as undergraduate students, can perform human motion analysis using a high-level programming language such as MATLAB. Four simulations of human motion are generated: walking, sitting and standing, side-step, and jump. The results of the walking simulation are validated by experiments. Simulation and experimental results are presented and discussed.
In a previous study by the authors, a possibilistic harmonic load flow (PHLF) approach was presented. The PHLF was capable of modelling, through possibility distributions, uncertainties regarding magnitude and composi...
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In a previous study by the authors, a possibilistic harmonic load flow (PHLF) approach was presented. The PHLF was capable of modelling, through possibility distributions, uncertainties regarding magnitude and composition in both linear (LL) and non-linear loads (NLL) connected at the power system (PS). However, in that approach, possibility non-interaction between parameters for modelling LL and NLL was assumed. Such assumption is quite conservative and conduces to uncertainty overestimation. In fact, there are well-defined physical relationships among model parameters that constrain the variability of these. This study presents an improved approach which overcomes the aforementioned drawback by including both linear and non-linear equality constraints into the non-linear programmingproblem used to compute the PHLF. These linear and non-linear equality constraints are specifically used to model the balance of active and reactive power, respectively, at each bus of the PS. The equality constrains inclusion is supported from a possibility theory point of view by means of the 'information fusion concept'. Influence of the possibility interaction consideration is evaluated in the IEEE 14-bus PS for harmonic analysis. Then, the complete PHLF is tested in a real 88-bus PS, and comparisons with Monte Carlo simulation results are performed and discussed.
In a paper by Wang and Elhag [Ying-Ming Wang and Taha M.S. Elhag, Fuzzy TOPSIS method based on alpha level sets with an application to bridge risk assessment, Expert Systems with Applications 31 (2006) 309-319], a fuz...
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In a paper by Wang and Elhag [Ying-Ming Wang and Taha M.S. Elhag, Fuzzy TOPSIS method based on alpha level sets with an application to bridge risk assessment, Expert Systems with Applications 31 (2006) 309-319], a fuzzy TOPSIS method on alpha level sets was introduced and a nonlinearprogramming solution procedure was presented. It is found that in the case that the fuzzy decision matrix is of the same dimension and needs no normalization, a pair of nonlinearprogramming models is incorrect for computing the relative closeness provided by the above paper. In this paper we present a correct pair of nonlinearprogramming models in the case of the same dimension and justify it from the viewpoint of monotonic function. An illustrated example for selecting the best supplier of metallic components used in a variety of transmission cables has been examined using the proposed programming models to fuzzy TOPSIS method and demonstrated its superiorities, rationalities.
Undervoltage load shedding (UVLS) is executed as a last resort to avoid voltage instability in critical situations. In this study, a robust UVLS scheme based on the point estimate method (PEM) is developed taking load...
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Undervoltage load shedding (UVLS) is executed as a last resort to avoid voltage instability in critical situations. In this study, a robust UVLS scheme based on the point estimate method (PEM) is developed taking load uncertainties into consideration. The utilised PEM converts the continuous probability distribution functions (PDFs) of load uncertainty to discrete statistical moments. The extracted moments could represent the behaviours of original continuous PDFs. The proposed stochastic UVLS strategy is expressed as a non-linear programmingproblem, which is optimised using sequential quadratic programming technique. The fulfilment of the suggested scheme is compared with Monte Carlo simulation technique for two IEEE 14-bus and IEEE 118-bus test grids.
The von Neumann minimax theorem has been applied in many areas and there are many extensions of the theorem. In Shi and Chang (1985) the theorem is generalized to a form in which a compactness condition of sets was re...
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The von Neumann minimax theorem has been applied in many areas and there are many extensions of the theorem. In Shi and Chang (1985) the theorem is generalized to a form in which a compactness condition of sets was replaced by a compactness condition of the function. The main aim of the paper is to extend Shi and Chang's result from convex sets to locally convex sets. First, a frame of variational methods on locally convex closed subsets of Banach manifolds is established. Lop-sided minimax theorem are next proven on locally convex closed subsets of Banach manifolds. Based on the lop-sided minimax theorem the proof of the main theorem is given. As applications of these theorems, a generalized Ky Fan's inequality is given as well as an existence theorem of equilibria in game theory. Finally a proof is given of an existence theorem for a solution of nonlinear programming problems which generalizes theorem 4.3 in Shi and Chang (1985).
The development of intelligent network and intelligent vehicle technology makes it possible for multi-vehicle cooperative driving. In this study, the multi-vehicle cooperative autonomous parking condition is addressed...
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The development of intelligent network and intelligent vehicle technology makes it possible for multi-vehicle cooperative driving. In this study, the multi-vehicle cooperative autonomous parking condition is addressed by establishing a vehicle kinematics model combined with dynamic constraints and endpoint and collision avoidance constraints. The autonomous parking trajectory planning problem is transformed into an optimal control problem. The shortest parking completion time is set as the optimal cost function, and the optimal control problem is discretised by using the Gauss pseudo-spectral method. Then, the non-linear programmingproblem is solved. Moreover, an initial guess generation strategy is proposed, and the iteration method is used to solve the problem by adding collision avoidance constraints to the collision situation of the vehicle to improve the convergence and robustness of the problem. The simulation model is built in MATLAB/Simulink to simulate multi-vehicle cooperative autonomous parking under different working conditions. The simulation results show that the proposed method can solve the multi-vehicle cooperative autonomous parking trajectory planning problem uniformly and effectively. Compared with the traditional pseudo-spectral method, the proposed method has a faster convergence speed.
The reactive power optimization (RPO) problem of power systems is a mixed-integer nonlinear programming problem, which can be computationally expensive. This paper applies the alternating direction method of multiplie...
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The reactive power optimization (RPO) problem of power systems is a mixed-integer nonlinear programming problem, which can be computationally expensive. This paper applies the alternating direction method of multipliers (ADMM) to solve it. By duplicating discrete control variables with one copy allowed to vary continuously, the RPO model is formulated as a modified model in which the objective function and constraints have a separable structure with respect to the continuous and discrete variables, except for the coupling constraint. We then applied the ADMM to solve this model with the separable structure, and hence the original problem is converted into two optimization sub-problems, which are nonlinearprogramming (NLP) and mixed-integer quadratic programming (MIQP) problems, respectively. To improve the convergence of the algorithm, we proposed an extended ADMM by adding the upper and lower limits on state variables into the MIQP sub-problem based on the sensitivities obtained in the NLP sub-problem. We also established a mechanism to filter out inactive inequality constraints in the MIQP sub-problem to improve computational speed. Moreover, numerical results tested on IEEE test systems and a real 739-bus system have shown the correctness of the proposed method and its adaptability for power systems with different sizes and configurations.
When some coefficients involved in nonlinear programming problems are taken as interval numbers, the problem becomes more challengeable than the original one. In the paper, a nonlinear programming problem with interva...
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ISBN:
(纸本)9781510813465
When some coefficients involved in nonlinear programming problems are taken as interval numbers, the problem becomes more challengeable than the original one. In the paper, a nonlinear programming problem with interval objective coefficients is considered, and a genetic algorithm is presented. Firstly, the original problem is transformed into a bilevel programming model without interval coefficients. In addition, a genetic algorithm is designed and used to deal with the transformed problem, in which the search space is decided by these intervals given in the original problem. Based on the proposed approach, the best and the worst optimal solutions as well as some intermediate solutions can be obtained. Finally, a computational example is solved and the results show that the proposed algorithm is efficient and robust.
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