Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550605
Elahe Aghapour, J. Farrell
This paper is concerned with the estimation of the state of a linear dynamic system when the measurements may contain outliers. The most common method for outlier detection utilizes the traditional Neyman-Pearson (NP) Kalman filter approach which ignores all residuals greater than a designer specified threshold. When measurements with outliers are used (i.e., missed detections), the estimated state becomes incorrect and the computed state error covariance is too small, yielding an over confidence in the estimator in the incorrect state estimate. When valid measurements are ignored, information is lost, but this is only critical if it causes the performance specification to be violated. In signal rich applications, with a large number of sensor measurements, a smaller subset of measurements than is accepted by the NP approach, could be able to achieve the specified level of performance with lower risk of including an outlier in the set of utilized measurements. In the moving-horizon approach used herein, the number of measurements available for state estimation is affected by both the number of measurements per time step and the number of time steps over which measurements are retained. This moving horizon, performance-specified, risk-averse state estimation approach will be formulated in an optimization setting that selects measurements from within the window, to achieve a specified level of performance while minimizing the incurred risk. Simulation results are included, which demonstrate the application of the technique and its enhanced performance and robustness to outliers relative to traditional methods.
{"title":"Performance-Specified Moving-Horizon State Estimation With Minimum Risk","authors":"Elahe Aghapour, J. Farrell","doi":"10.23919/ECC.2018.8550605","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550605","url":null,"abstract":"This paper is concerned with the estimation of the state of a linear dynamic system when the measurements may contain outliers. The most common method for outlier detection utilizes the traditional Neyman-Pearson (NP) Kalman filter approach which ignores all residuals greater than a designer specified threshold. When measurements with outliers are used (i.e., missed detections), the estimated state becomes incorrect and the computed state error covariance is too small, yielding an over confidence in the estimator in the incorrect state estimate. When valid measurements are ignored, information is lost, but this is only critical if it causes the performance specification to be violated. In signal rich applications, with a large number of sensor measurements, a smaller subset of measurements than is accepted by the NP approach, could be able to achieve the specified level of performance with lower risk of including an outlier in the set of utilized measurements. In the moving-horizon approach used herein, the number of measurements available for state estimation is affected by both the number of measurements per time step and the number of time steps over which measurements are retained. This moving horizon, performance-specified, risk-averse state estimation approach will be formulated in an optimization setting that selects measurements from within the window, to achieve a specified level of performance while minimizing the incurred risk. Simulation results are included, which demonstrate the application of the technique and its enhanced performance and robustness to outliers relative to traditional methods.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"07 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130536511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550574
R. Brehm, M. H. Ramezani, J. Jouffroy
An approach for distributed coordinated scheduling of storage capacities is presented. When storage capacities are connected in the same grid, behind a common transformer substation, mutual charging and discharging can occur, which can be prevented by the herein introduced coordination method. When cooperation is incorported, storage capacities can be operated as a virtual microgrid. The cooperation between nodes is based on the formulation of a simple objective function for coordination. The cooperation objective is then combined with each node's local objective, which is the increase of self consumption, such that load is released off the the grid. A qualitative reflection on the practical use of three distributed algorithms, to solve the formulated optimisation problem is provided. The Jacobi algorithm is qualified to be preferable for large-scale networks with a great number of nodes, and the Gauss-Seidel algorithm is preferable when less nodes cooperate. To illustrate the concept and show the effect of coordination for prevention of mutual charginy/discharging of storage capacities in a VMG, two comparative case-study scenario are presented.
{"title":"Distributed coordination of energy-storage capacities in virtual microgrids","authors":"R. Brehm, M. H. Ramezani, J. Jouffroy","doi":"10.23919/ECC.2018.8550574","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550574","url":null,"abstract":"An approach for distributed coordinated scheduling of storage capacities is presented. When storage capacities are connected in the same grid, behind a common transformer substation, mutual charging and discharging can occur, which can be prevented by the herein introduced coordination method. When cooperation is incorported, storage capacities can be operated as a virtual microgrid. The cooperation between nodes is based on the formulation of a simple objective function for coordination. The cooperation objective is then combined with each node's local objective, which is the increase of self consumption, such that load is released off the the grid. A qualitative reflection on the practical use of three distributed algorithms, to solve the formulated optimisation problem is provided. The Jacobi algorithm is qualified to be preferable for large-scale networks with a great number of nodes, and the Gauss-Seidel algorithm is preferable when less nodes cooperate. To illustrate the concept and show the effect of coordination for prevention of mutual charginy/discharging of storage capacities in a VMG, two comparative case-study scenario are presented.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126920787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550599
A. Taniguchi, K. Fujimoto, Yoshiharu Nishida
In this paper, we propose a parameter estimation method for nonlinear state-space models based on the variational Bayes. It is shown that the variational posterior distribution of the hidden states is equivalent the probability estimated by a nonlinear smoother of an augmented nonlinear state-space model. This enables us to obtain the variational posterior distribution of the hidden states by implementing a variety of existing nonlinear filtering and smoothing algorithms. By employing a Gaussian mixture distribution as a candidate probability density function of the hidden states, we propose an algorithm to compute multimodal posterior distributions which are not able to be handled by the existing results.
{"title":"On System Identification of Nonlinear State-Space Models Based on Variational Bayes: Multimodal Distribution Case","authors":"A. Taniguchi, K. Fujimoto, Yoshiharu Nishida","doi":"10.23919/ECC.2018.8550599","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550599","url":null,"abstract":"In this paper, we propose a parameter estimation method for nonlinear state-space models based on the variational Bayes. It is shown that the variational posterior distribution of the hidden states is equivalent the probability estimated by a nonlinear smoother of an augmented nonlinear state-space model. This enables us to obtain the variational posterior distribution of the hidden states by implementing a variety of existing nonlinear filtering and smoothing algorithms. By employing a Gaussian mixture distribution as a candidate probability density function of the hidden states, we propose an algorithm to compute multimodal posterior distributions which are not able to be handled by the existing results.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129130041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550506
Sultan Alghamdi, Johannes Schiffer, E. Fridman
Consensus algorithms are promising control schemes for secondary control tasks in microgrids. Since consensus algorithms are distributed protocols, communication efforts and time delays are significant factors for the control design and performance. Moreover, both the electrical and the communication layer in a microgrid are continuously exposed to exogenous disturbances. Motivated by this, we derive a synthesis for a consensus-based secondary frequency controller that guarantees robustness with respect to time-varying delays and in addition provides the option to trade off $L_{2}$ disturbance attenuation against the number of required communication links. The efficacy of the proposed approach is illustrated via simulations based on the CIGRE benchmark medium voltage distribution network.
{"title":"Distributed Secondary Frequency Control Design for Microgrids: Trading Off L2-Gain Performance and Communication Efforts under Time-Varying Delays","authors":"Sultan Alghamdi, Johannes Schiffer, E. Fridman","doi":"10.23919/ECC.2018.8550506","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550506","url":null,"abstract":"Consensus algorithms are promising control schemes for secondary control tasks in microgrids. Since consensus algorithms are distributed protocols, communication efforts and time delays are significant factors for the control design and performance. Moreover, both the electrical and the communication layer in a microgrid are continuously exposed to exogenous disturbances. Motivated by this, we derive a synthesis for a consensus-based secondary frequency controller that guarantees robustness with respect to time-varying delays and in addition provides the option to trade off $L_{2}$ disturbance attenuation against the number of required communication links. The efficacy of the proposed approach is illustrated via simulations based on the CIGRE benchmark medium voltage distribution network.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130659587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ecc.2018.8550454
{"title":"ECC 2018 Committees","authors":"","doi":"10.23919/ecc.2018.8550454","DOIUrl":"https://doi.org/10.23919/ecc.2018.8550454","url":null,"abstract":"","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123868972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550382
Francesco Borgioli, W. Michiels
In this paper we propose an algorithm to compute the distance to instability of a linear system of delay differential equations (DDEs) containing uncertainties in the delay terms as well as in matrices coefficients. For what regards the system matrices, any structure on the perturbation can be considered in order to allow only specific parameters to change; moreover, real-valued matrix perturbations are taken into account. The algorithm relies on the computation of the pseudospectral ab- scissa of the system and performs a bisection-Newton's method to find the minimum size of the perturbation that generates instability. A few illustrative examples, including a model for a rotating cutting machine, finally show the correctness and the efficiency of the method.
{"title":"Computing the distance to instability for delay systems with uncertainties in the system matrices and in the delay terms","authors":"Francesco Borgioli, W. Michiels","doi":"10.23919/ECC.2018.8550382","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550382","url":null,"abstract":"In this paper we propose an algorithm to compute the distance to instability of a linear system of delay differential equations (DDEs) containing uncertainties in the delay terms as well as in matrices coefficients. For what regards the system matrices, any structure on the perturbation can be considered in order to allow only specific parameters to change; moreover, real-valued matrix perturbations are taken into account. The algorithm relies on the computation of the pseudospectral ab- scissa of the system and performs a bisection-Newton's method to find the minimum size of the perturbation that generates instability. A few illustrative examples, including a model for a rotating cutting machine, finally show the correctness and the efficiency of the method.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123648785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550488
Özkan Karabacak, R. Wisniewski, J. Leth
For a given invariant set of a dynamical system, it is known that the existence of a Lyapunov-type density function, called Lyapunov density or Rantzer's density function, may imply the convergence of almost all solutions to the invariant set, in other words, the almost global stability (also called almost everywhere stability) of the invariant set. For discrete-time systems, related results in literature assume that the state space is compact and the invariant set has a local basin of attraction. We show that these assumptions are redundant. Using the duality between Frobenius-Perron and Koopman operators, we provide a Lyapunov density theorem for discrete-time systems without assuming the compactness of the state space or any local attraction property of the invariant set. As a corollary to this new discrete-time Lyapunov density theorem, we provide a continuous-time Lyapunov density theorem which can be used as an alternative to Rantzer's original theorem, especially where the solutions are known to exist globally.
{"title":"On the Almost Global Stability of Invariant Sets","authors":"Özkan Karabacak, R. Wisniewski, J. Leth","doi":"10.23919/ECC.2018.8550488","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550488","url":null,"abstract":"For a given invariant set of a dynamical system, it is known that the existence of a Lyapunov-type density function, called Lyapunov density or Rantzer's density function, may imply the convergence of almost all solutions to the invariant set, in other words, the almost global stability (also called almost everywhere stability) of the invariant set. For discrete-time systems, related results in literature assume that the state space is compact and the invariant set has a local basin of attraction. We show that these assumptions are redundant. Using the duality between Frobenius-Perron and Koopman operators, we provide a Lyapunov density theorem for discrete-time systems without assuming the compactness of the state space or any local attraction property of the invariant set. As a corollary to this new discrete-time Lyapunov density theorem, we provide a continuous-time Lyapunov density theorem which can be used as an alternative to Rantzer's original theorem, especially where the solutions are known to exist globally.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120950403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550438
A. Malyshev, R. Quirynen, A. Knyazev, S. D. Cairano
We investigate direct numerical solvers in linear model predictive control, where the prediction model is given by linear systems subject to linear inequality constraints on the state and the input, and the performance index is convex and quadratic. The inequality constraints are treated by the primal-dual interior-point method. We propose a novel direct solver based on the augmented Lagrangian regularization of a reduced Hessian. The new solver has the same arithmetic complexity as the factorized Riccati recursion. The direct solver can be implemented in terms of BLAS3 matrix operations.
{"title":"A regularized Newton solver for linear model predictive control","authors":"A. Malyshev, R. Quirynen, A. Knyazev, S. D. Cairano","doi":"10.23919/ECC.2018.8550438","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550438","url":null,"abstract":"We investigate direct numerical solvers in linear model predictive control, where the prediction model is given by linear systems subject to linear inequality constraints on the state and the input, and the performance index is convex and quadratic. The inequality constraints are treated by the primal-dual interior-point method. We propose a novel direct solver based on the augmented Lagrangian regularization of a reduced Hessian. The new solver has the same arithmetic complexity as the factorized Riccati recursion. The direct solver can be implemented in terms of BLAS3 matrix operations.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114101626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550167
Julio Luna, S. Gros, Ole Falkenberg, A. Schild
In this paper, an Artificial Neural Network (ANN) methodology for estimating the tower fatigue of a wind turbine (WT) is developed. Specifically, the fatigue is estimated using an ANN that receives frequency-domain measurements of the tower base position and velocity. The frequencies are selected using an algorithm that detects the most relevant values and generates a sampling grid. The complexity of the ANN-based fatigue estimation is analysed to study the viability of its deployment in a real-time Nonlinear Model Predictive Control (NMPC) formulation.
{"title":"A Sparse ANN-based Fatigue Estimation for Wind Turbine Control based on NMPC","authors":"Julio Luna, S. Gros, Ole Falkenberg, A. Schild","doi":"10.23919/ECC.2018.8550167","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550167","url":null,"abstract":"In this paper, an Artificial Neural Network (ANN) methodology for estimating the tower fatigue of a wind turbine (WT) is developed. Specifically, the fatigue is estimated using an ANN that receives frequency-domain measurements of the tower base position and velocity. The frequencies are selected using an algorithm that detects the most relevant values and generates a sampling grid. The complexity of the ANN-based fatigue estimation is analysed to study the viability of its deployment in a real-time Nonlinear Model Predictive Control (NMPC) formulation.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":"236 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116496849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.23919/ECC.2018.8550156
R. V. D. Weijst, T. Keulen, F. Willems
Advanced control concepts are required to maximize the fuel-efficiency of Diesel engines and to comply with emission legislation. The aim of this paper is to develop a controller that fully utilizes the fuel-path and air-path hardware, and is adaptive for real-world disturbances. The control design comprises a feedback control system, which uses air-path actuators and fuel injection settings to robustly track engineout NOx emission and engine power demands, as well as two parameters that are known to influence the NOx emission versus fuel consumption trade-off; combustion phasing and pumping losses. Furthermore, an on-line implementable convex cost criterion is proposed that evaluates the injector opening time to obtain a cost output which is equivalent to fuel efficiency. A multivariable constrained extremum-seeking method is applied to minimize the cost output, as a function of combustion phasing and pumping losses, subject to constraints on the tracking performance of the low-level control system. The control design is implemented on a Euro-VI Diesel engine equipped with exhaust gas recirculation and a variable geometry turbine, as well as in-cylinder pressure sensors. The experiments demonstrate the effectiveness of the applied extremum-seeking approach in finding the (constrained) optimum, for a constant engine speed and torque.
{"title":"On-line fuel-efficiency optimization of Diesel engines using constrained multivariable extremum-seeking","authors":"R. V. D. Weijst, T. Keulen, F. Willems","doi":"10.23919/ECC.2018.8550156","DOIUrl":"https://doi.org/10.23919/ECC.2018.8550156","url":null,"abstract":"Advanced control concepts are required to maximize the fuel-efficiency of Diesel engines and to comply with emission legislation. The aim of this paper is to develop a controller that fully utilizes the fuel-path and air-path hardware, and is adaptive for real-world disturbances. The control design comprises a feedback control system, which uses air-path actuators and fuel injection settings to robustly track engineout NOx emission and engine power demands, as well as two parameters that are known to influence the NOx emission versus fuel consumption trade-off; combustion phasing and pumping losses. Furthermore, an on-line implementable convex cost criterion is proposed that evaluates the injector opening time to obtain a cost output which is equivalent to fuel efficiency. A multivariable constrained extremum-seeking method is applied to minimize the cost output, as a function of combustion phasing and pumping losses, subject to constraints on the tracking performance of the low-level control system. The control design is implemented on a Euro-VI Diesel engine equipped with exhaust gas recirculation and a variable geometry turbine, as well as in-cylinder pressure sensors. The experiments demonstrate the effectiveness of the applied extremum-seeking approach in finding the (constrained) optimum, for a constant engine speed and torque.","PeriodicalId":222660,"journal":{"name":"2018 European Control Conference (ECC)","volume":" 102","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113952485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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