Modelling uncertainty for leak localization in Water Networks

The performance and success of model-based leak localization methods applied to water distribution networks (WDN) highly depends on the uncertainty of the system considered. This work proposes an original method of modeling the effect of uncertainties in these networks. The proposed method is based on the collection of real data in the water network in the absence of leaks. The discrepancy (residual) between the measured data and the one provided by a simulator of the network in normal operation is used to extrapolate the possible residuals in the different leak scenarios. In addition, indicators for assessing the effect of uncertainty in the performance of leak localization methods based on residual correlation analysis are provided. The error in terms of correlation intervals and leak localzation assessment between the proposed approximation and the real one is studied by means a simplified model of the WDN of Hanoi (Vietnam).Postprint (published version

Robust optimization based energy dispatch in smart grids considering demand uncertainty

In this study we discuss the application of robust optimization to the problem of economic energy dispatch in smart grids. Robust optimization based MPC strategies for tackling uncertain load demands are developed. Unexpected additive disturbances are modelled by defining an affine dependence between the control inputs and the uncertain load demands. The developed strategies were applied to a hybrid power system connected to an electrical power grid. Furthermore, to demonstrate the superiority of the standard Economic MPC over the MPC tracking, a comparison (e.g average daily cost) between the standard MPC tracking, the standard Economic MPC, and the integration of both in one-layer and two-layer approaches was carried out. The goal of this research is to design a controller based on Economic MPC strategies, that tackles uncertainties, in order to minimise economic costs and guarantee service reliability of the system.Postprint (author's final draft

Fault tolerant model predictive control of open channels

Automated control of water systems (irrigation canals, navigation canals, rivers etc.) relies on the measured data. The control action is calculated, in case of feedback controller, directly from the on-line measured data. If the measured data is corrupted, the calculated control action will have a different effect than it is desired. Therefore, it is crucial that the feedback controller receives good quality measurement data. On-line fault detection techniques can be applied in order to detect the faulty data and correct it. After the detection and correction of the sensor data, the controller should be able to still maintain the set point of the system. In this paper this principle using the sensor fault masking is applied to model predictive control of open channels. A case study of a reach of the northwest of the inland navigation network of France is presented. Model predictive control and water level sensor masking is applied.Peer ReviewedPostprint (published version

Robustness analysis of sensor placement for leak detection and location under uncertain operating conditions

Trabajo presentado a la 16th Water Distribution System Analysis Conference ( WDSA2014): Urban Water Hydroinformatics and Strategic Planning, celebrada en Bari (Italia) del 14 al 17 de julio.-- Under a Creative Commons license.Some pressure sensor placement methods for leak detection and location in water distribution networks are based on the pressure sensitivity matrix analysis. This matrix depends on the network demands, which are nondeterministic, and the leak magnitudes, which are unknown. In this paper, the robustness of a sensor placement methodology against the fault sensitivity matrix uncertainty is studied. The robustness study is illustrated by means of a small academic network as well as a district metered area in the Barcelona water distribution network. Results reveal that this uncertainty should be taken into account in the sensor placement methodology.This work has been funded by the Spanish Ministry of Economy and Competitiveness through the CICYT project SHERECS (ref. DPI2011-26243), and by the European Commission through contract EFFINET (ref. FP7-ICT2011-8-318556).Peer Reviewe

Gain-scheduled Smith predictor PID-based LPV controller for open-flow canal control

In this paper, a gain-scheduled Smith Predictor PID controller is proposed for the control of an open-flow canal system that allows for dealing with large variation in operating conditions. A linear parameter varying (LPV) control-oriented model for open-flow canal systems based on a second-order delay Hayami model is proposed. Exploiting the second-order structure of this model, an LPV PID controller is designed using H∞ and linear matrix inequalities pole placement. The controller structure includes a Smith Predictor, real time estimated parameters from measurements (including the known part of the delay) that schedule the controller and predictor and unstructured dynamic uncertainty, which covers the unknown portion of the delay. Finally, the proposed controller is validated in a case study based on a single real reach canal: the Lunax Gallery at Gascogne (France).This work has been funded by contract ref. HYFA DPI2008-01996 and WATMAN DPI2009-13744 of Spanish Ministry of Education.Peer Reviewe

Modelling uncertainty for leak localization in Water Networks

The performance and success of model-based leak localization methods applied to water distribution networks (WDN) highly depends on the uncertainty of the system considered. This work proposes an original method of modeling the effect of uncertainties in these networks. The proposed method is based on the collection of real data in the water network in the absence of leaks. The discrepancy (residual) between the measured data and the one provided by a simulator of the network in normal operation is used to extrapolate the possible residuals in the different leak scenarios. In addition, indicators for assessing the effect of uncertainty in the performance of leak localization methods based on residual correlation analysis are provided. The error in terms of correlation intervals and leak localzation assessment between the proposed approximation and the real one is studied by means a simplified model of the WDN of Hanoi (Vietnam).Peer ReviewedPostprint (published version

Gestió relacional i governança : mecanismes de resolució de conflictes en les polítiques de la Generalitat

Aquest no és, en el sentit estricte del terme, un estudi sobre mediació, ja que -per expressar-ho de manera simplificada- no s'ocupa de com donar sortida al conflicte entre dues parts sense necessitat d'arribar a les instàncies judicials. En aquest document, en canvi, ens interessem pels conflictes col·lectius que envolten el disseny i la implementació de polítiques públiques. I ens interessa, sobretot, analitzar com en un entorn de creixent complexitat, aquests conflictes es converteixen en allò que la literatura ha anomenat wicked problems (problemes maleïts), és a dir, en situacions on el conflicte no troba sortida, especialment quan l'administració pública actua des de la clàssica lògica de la jerarquia i l'especialització. En aquest sentit, usem els conceptes administració relacional i governança per re-ferir-nos a una nova forma d'abordar els conflictes entorn les polítiques públiques. Una manera de fer polítiques públiques que substitueix la jerarquia i l'especialització pel diàleg i la interacció; trobant, així, un punt de contacte amb la perspectiva de la mediació. Il·lustrem aquest plantejament amb tres anàlisi de casos, els quals ens serveixen per exemplificar com es pot abordar la resolució dels conflictes des del diàleg i la interacció. Els tres casos -la política d'equipaments penitenciaris, la política d'aigua i la política de construcció de la línia de molt alta tensió (la MAT-, a més, ens serveixen per proposar un protocol sobre com abordar polítiques complexes en societats complexes. Tanmateix, abans d'abordar els casos i d'extreure'n algunes conclusions, presentem una breu anàlisi del tipus de queixes i demandes que arriben al Síndics de Catalunya. Pretenem, d'aquesta manera, vincular els conflictes entorn les polítiques públiques amb la creixent insatisfacció d'una part de la ciutadania respecte a les accions dels seus governs i les seves administracions

Optimal energy dispatch in a smart micro-grid system using economic model predictive control

The problem of energy dispatch in heterogeneous complex systems such as smart grids cannot be efficiently addressed using classical control or ad-hoc methods. This paper discusses the application of Economic Model Predictive Control (EMPC) to the management of a smart micro-grid system connected to an electrical power grid. The considered system is composed of several subsystems, namely some photovoltaic (PV) panels, a wind generator, a hydroelectric generator, a diesel generator, and some storage devices (batteries). The batteries are charged with the energy from the PV panels, wind and hydroelectric generators, and they are discharged whenever the generators produce less energy than needed. The subsystems are interconnected via a DC Bus, from which load demands are satisfied. Modeling smart grids components is based on the generalized flow-based networked systems paradigm, and assuming energy generators to be stable, load demands and energy prices are known. This study shows that EMPC is economically superior to a two-layer hierarchical MPC.Peer ReviewedPostprint (author's final draft

Fault tolerant model predictive control of open channels

Trabajo presentado a la USCID Conference on Planning, Operation and Automation of Irrigation Delivery Systems celebrada en Phoenix, Arizona (US) del 2 al 5 de diciembre de 2014.Automated control of water systems (irrigation canals, navigation canals, rivers etc.) relies on the measured data. The control action is calculated, in case of feedback controller, directly from the on-line measured data. If the measured data is corrupted, the calculated control action will have a different effect than it is desired. Therefore, it is crucial that the feedback controller receives good quality measurement data. On-line fault detection techniques can be applied in order to detect the faulty data and correct it. After the detection and correction of the sensor data, the controller should be able to still maintain the set point of the system. In this paper this principle using the sensor fault masking is applied to model predictive control of open channels. A case study of a reach of the northwest of the inland navigation network of France is presented. Model predictive control and water level sensor masking is applied.Peer Reviewe

Robust optimization based energy dispatch in smart grids considering simultaneously multiple uncertainties: load demands and energy prices

Solving the problem of energy dispatch in a heterogeneous complex system is not a trivial task. The problem becomes even more complex considering uncertainties in demands and energy prices. This paper discusses the development of several Economic Model Predictive Control (EMPC) based strategies for solving an energy dispatch problem in a smart micro-grid. The smart grid components are described using control-oriented model approach. Considering uncertainty of load demands and energy prices simultaneously, and using an economic objective function, leads to a non-linear non-convex problem. The technique of using an affine dependent controller is used to convexify the problem. The goal of this research is the development of a controller based on EMPC strategies that tackles both endogenous and exogenous uncertainties, in order to minimize economic costs and guarantee service reliability of the system. The developed strategies have been applied to a hybrid system comprising some photovoltaic (PV) panels, a wind generator, a hydroelectric generator, a diesel generator, and some storage devices interconnected via a DC Bus. Additionally, a comparison between the standard EMPC, and its combination with MPC tracking in single-layer and two-layer approaches was also carried out based on the daily cost of energy production.Postprint (published version