The paper proposes methods and algorithms for optimal tuning of power system stabilizers (PSS). The methods are based on the representation of the power system in the form of a graph and the construction for the graph...
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The paper proposes methods and algorithms for optimal tuning of power system stabilizers (PSS). The methods are based on the representation of the power system in the form of a graph and the construction for the graph of the power system of an equivalent multi-connected system of automatic control of modes of electromechanical oscillations. The node dynamics is represented by a simplified model of an oscillator together with a proportional-differential regulator, which is fair for describing a real generator with a PSS only in the region of low frequencies of dangerous oscillations. The problem of optimal tuning PSS parameters is formulated and methods for its solution based on heuristic intelligence algorithms and the method of tuning with implicit reference model are proposed. The effectiveness of the proposed methods is demonstrated on the model of a modified classical two-area Kundur test system with tuning parameters of PSS of three generators.
The computational demands of Model predictive control (MPC) are well known, and due to its internal constrained optimiser, historically has been ill-suited for embedded controllers designed to tackle high-speed applic...
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The computational demands of Model predictive control (MPC) are well known, and due to its internal constrained optimiser, historically has been ill-suited for embedded controllers designed to tackle high-speed applications. This paper explores the options of developing a low-cost lightweight MPC controller destined for micro-controller or FPGA architectures for modest applications demanding reasonable controller horizons. An object based MPC development tool is introduced and applied to an experimental 4-tank level system to explore the performance of the algorithm.
Orthogonal frequency-division multiplexing (OFDM) modulation can be utilized to deal with severe channel conditions without complex equalization. However, in a fast-fading channel, Doppler spread caused by user mobili...
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Orthogonal frequency-division multiplexing (OFDM) modulation can be utilized to deal with severe channel conditions without complex equalization. However, in a fast-fading channel, Doppler spread caused by user mobility destroys the orthogonality among subcarriers, prompting intercarrier interference (ICI). In this paper, the OFDM ICI reduction problem is formulated as a combinatorial optimization problem. Two relaxation methods are proposed to relax the maximum-likelihood detection problem into convex quadratic programming (QP) problems. To further reduce computational complexity, the QP problems are solved by limiting the search to the two-dimensional subspace. A low-bit descent search can also be employed to improve the system performance. The extension to higher-order quadrature amplitude modulation (QAM) OFDM systems is also addressed. Performance results are given which demonstrate that the integer QP relaxation-based algorithms provide excellent performance with reasonable computational complexity.
In this paper the optimal regulator design is analized in the context of multicriteria optimization theory. We propose one interactive algorithm which permits us to overcome the well known difficulties when choosing t...
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In this paper the optimal regulator design is analized in the context of multicriteria optimization theory. We propose one interactive algorithm which permits us to overcome the well known difficulties when choosing the weghting matrices in the cost functional. Moreover we present a procedure to design low parameter sensitivity optimal regulators by using a bicriteria formulation. A program package is also presented. To improve the efficiency of the interactive multicriteria optimization algoritms, an interaction interpreter has been included in the package. This interpreter uses fuzzy set theory to infer sequential modifications on the quadratic index from designer qualitative linguistic diagnosis formulated for each criterion.
This paper utilizes the results of a panel survey, conducted after the General Elections of February and October 1974, to obtain the estimated voter transition probabilities for constituencies contested on each occasi...
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This paper utilizes the results of a panel survey, conducted after the General Elections of February and October 1974, to obtain the estimated voter transition probabilities for constituencies contested on each occasion by candidates representing the Conservative, Labour and Liberal parties. The panel estimates are compared with those derived by McCarthy and Ryan (1977) who used a quadratic programming method. Although the panel results underestimate the proportion of the electorate who did not vote, they provide clear evidence that the quadratic programming oversimplifies the pattern of voting change. The panel results also show clearly that the pattern of voting change between two elections is affected by the relative party strengths in the first election.
Nonlinear forms such as the cone, sphere, cylinder, and torus present significant problems in representation and verification. In this paper we examine linear and nonlinear forms using a heavily modified support vecto...
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Nonlinear forms such as the cone, sphere, cylinder, and torus present significant problems in representation and verification. In this paper we examine linear and nonlinear forms using a heavily modified support vector machine (SVM) technique. The SVM approach applied to regression problems is used to derive quadratic programming problems that allow for generalized symbolic solutions to nonlinear regression. We have tested our approach to several geometries and achieved excellent results even with small data sets, making this method robust and efficient. More importantly, we identify process or inspection tendencies that could help in better designing the processes. Adaptive feature verification can be achieved through effective identification of the manufacturing pattern.
In reaction systems, state estimators are used to improve the quality of estimates using measurements and process models with the number of moles or concentrations as states. The model of reaction systems can be refor...
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In reaction systems, state estimators are used to improve the quality of estimates using measurements and process models with the number of moles or concentrations as states. The model of reaction systems can be reformulated in the extent domain with the reaction and flow extents as states. This work exploits the properties of the extents, such as nonnegativity and monotonicity, and formulates nonlinear and linear Shape-Constrained Moving Horizon Estimators (SCMHE) for reaction systems. It is shown that the linear SCMHE is a quadratic programming problem, and hence, it is computationally less expensive. The performance of the SCMHE schemes is compared with the Extended Kalman filters (EKF) and MHE in the concentration domain via simulation studies using two examples, namely, gas-phase isothermal batch reactor and lactic acid production in a fed-batch reactor. It is shown that the linear SCMHE provides better performance than EKF with a similar average computational time, while nonlinear SCMHE is computationally cheaper and performs better than the MHE in the concentration or mole domain.
This paper presents a new control design method for the control of flexible systems that not only guarantees closed-loop asymptotic stability but also effectively suppresses vibration. This method allows integrated de...
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This paper presents a new control design method for the control of flexible systems that not only guarantees closed-loop asymptotic stability but also effectively suppresses vibration. This method allows integrated determination of actuator/sensor locations and feedback gain via minimization of an energy criterion, which is chosen as the integrated total energy stored in the system. The energy criterion is determined via an efficient solution of the Lyapunov equation and minimized with a quasi-Newton or recursive quadratic programming algorithm. The prerequisite for this optimal design method is that the controlled system be asymptotically stable. This study shows that when the controller structure is a collocated direct velocity feedback design with positive definite feedback gain, the number and placement of actuators/sensors are the only factors needed to determine necessary and sufficient conditions for ensuring closed-loop asymptotic stability. The application of this method to a simple flexible structure confirms the direct relationship between our optimization criterion and effectiveness in vibration suppression.
In this paper, the robust control of constrained discrete-time linear time-varying or uncertain systems affected by bounded additive disturbance is considered. The main idea is to use an interpolation technique betwee...
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In this paper, the robust control of constrained discrete-time linear time-varying or uncertain systems affected by bounded additive disturbance is considered. The main idea is to use an interpolation technique between several local unconstrained robust optimal controls. From the implementation point of view, the scheme is shown to be computationally attractive, at each time instant a quadratic programming (QP) problem being solved on-line. The proofs of recursive feasibility of the optimization procedure and ISS stability of the closed loop system are given.
This study presents a multi-objective operation optimisation model for urban power grids with flexible switching (FS) stations to comprehensively improve system security and reliability. In the proposed model, uncerta...
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This study presents a multi-objective operation optimisation model for urban power grids with flexible switching (FS) stations to comprehensively improve system security and reliability. In the proposed model, uncertainties associated with load variation and component failures are considered. Moreover, constraints after a feeder or transformer N-1 contingency are preliminarily formulated. The operation problem optimises the apparent power of feeder section loading. The combination of normal boundary intersection and sequential quadratic programming is employed to solve the non-linear optimisation model. A case study carried out on a test 75-feeder distribution grid with FS stations demonstrates the effectiveness of the proposed model and solving method. Compared with conventional distribution loadability, the optimal load distribution solution obtained in this study provides a trade-off between system security and reliability. The coordinated operation optimisation method is suitable for urban smart distribution grids featured by distribution automation and large-scale interconnections.
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