13th International Science Conference
Diagnostics of Processes and Systems
10-13 September 2017, Sandomierz, Poland
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Plenary papers

Diagnosis and Fault-tolerant Control of Critical Infrasctructures

Vicenc PUIG

In modern societies, the reliable and continuous operation of certain infrastructures plays a fundamental role in the quality of life, economic development and security of nations. Large-scale critical infrastructure systems (CIS), especially those located in urban areas (as drinking water or gas infrastructures), is a subject of increasing concern. Because of this, these infrastructures are considered critical and it is very important to develop management systems that guarantee a reliable and continuous operation of these infrastructures. Other important aspects of the management of these infrastructures is that their operation must use efficiently the resources that they deliver (e.g., water, gas, ...), and also be efficient from an economic point of view and guarantee future supply.

The critical nature of these infrastructures makes necessary a management system able to take into account their specific features and operation limits in presence of the uncertainties related to their operation. Thus, it is of paramount importance to have a control system in the management system that, from sensor measurements and available predictions of external influential variables, finds the proper way to operate the infrastructure in an efficient, safe and continuous manner.

This talk will present several approaches for diagnosis and fault-tolerant control of CIS including:

  • the analysis of these systems to understand the weaknesses and risks in case some fault appears,
  • fault diagnosis including sensor validation/reconstruction and leak localization,
  • fault tolerant control schemes and assessment of the fault tolerance,
  • inclusion of health-aware and reliable mechanism in the CIS control systems.

Algorithms and methodologies will be illustrated with some real case studies.

Paper in language: englisch
Date: 11.09 (9:00)

Vicenc Puig

Technical University of Catalonia

Control loops performance monitoring

Andrzej GĄSECKI

Refinery, petrochemical, chemical plants control systems excellent performance is critical for proper efficiency safety, reliability, energy media consumption, process performance. Operational excellence is necessary to meet the demands of competitive market. Poorly performing control loops can cause operational problems resulting in reduced products quality and capacity, accelerated equipment wear, increased emission and other difficult to predict isssues. Bad performance of basic control layer makes impossible to obtain benefits from APC and optimization applications. Identification of control loop problems is not easy, specially when thousands of loops are implemented. In every loop problem can be caused by measurement or control valve malfunction, wrong tuning or improper design. Sometimes operators change the mode of operation to manual without any justified reason. All these problems can be mitigated by advanced diagnostic application which online continuously monitors control loops performance.

The presentation will describe the diagnostic application functionality and features, experience and benefits from the first year of use.

Such diagnostic application was installed, commissioned and started on refinery and petrochemical plants in Plock. Software collects data from different DCS systems, makes about 70 different types of analyses, which results are condensed in response, stability and service indexes and common control loop performance index, diagnoses the root cause of poor control performance, gives advice to maintenance engineer, calculates KPI for the loops and plants, generates reports for defined users. Implemented analysis groups: statistical, correlation analysis- autocorrelation of process variable, cross correlation of error and output, cycle analysis, time series analysis, power spectrum analysis – dominant frequencies, significance of oscillation, modified Harris index, analysis specific to control valves and loop service, etc. Process interactions are also identified. Examples of detected control problems: pv noise, static sensor, to many bad data, valve stiction, leaking valve, undersized or oversized valve, to big valve travel per day, too many valve cycle per day, sluggish tuning., aggressive tuning, saturation of controller output, wrong mode of operation, etc.

Paper in language: englisch
Date: 11.09 (15:15)

Andrzej Gąsecki
Automation Department
PKN Orlen S.A.

Supporting of postural deformities diagnosis using 3D scanning

Robert SITNIK,Jakub MICHOŃSKI,Wojciech GLINKOWSKI

Traditionally posture deformity assessment for screening purposes is performed by visual examination of patient’s body by an expert. During further follow-up of the diagnosed deformity full spine, X-Ray 2D images are acquired. 3D medical imaging (Computer Tomography and MRI) is used when the spinal surgery is considered. Visual examination is subjective and is strongly dependent on expert knowledge. X-Ray and tomographic imaging exposure can be contraindicated in some cases (i.e. pregnancy). During last two decades, the dynamic development of methods and systems for 3D scanning and algorithms for measurement data analysis is observed. 3D scanning is successfully applied in modern industrial production lines, documentation of cultural heritage and human body analysis. Recently, algorithms for data analysis allow for 100% inspection of complex geometry and have increasing support for control of the technological process parameters on the base of calculated deviation between measurement and assumed 3D model.

In this paper, we present an alternative approach for back posture analysis based on structured light 3D scanning. We present three different systems: mobile solution for prescreening of back shape, full body 3D scanner for monitoring of posture deformities and 4D scanner for dynamic analysis. Such a three-stage system fit into the idea of evidence-based medicine.

Each of presented devices produces 3D geometry data representing the surface of patient’s body. Each of them has also accompanying software that has been developed for processing of geometry data into a final form that is easily interpreted by medical experts (angles, asymmetries, 3D models, changes in time of analyzed measures, etc.).

Paper in language: englisch
Date: 12.09 (9:00)

Robert Sitnik
Wydział Mechatroniki
Politechnika Warszawska

Integrated Fault Diagnosis and Fault-Tolerant for Constrained Dynamic Systems

Marcin WITCZAK,Marcin PAZERA

Fault diagnosis and fault-tolerant control meet increasing demands of modern control systems of increasing complexity. They give an ability to detect, isolate and determine size of a fault before it will transform into a failure and then to minimize its impact as well as ensuring predefined quality demands regarding its performance. Taking into account a significant number of sensors and actuators present in modern control processes, this is not a trivial task. The main reason behind such a situation is the fact that there are various interaction between the above equipment as well as the fact that their immediate replacement with non-faulty counterparts is, in most cases, impossible. This justifies the need for the design of virtual sensors enabling replacement of measurements provided by their hardware counterparts by their expected values calculated based on available measurements processed by dedicated algorithms. The problem is even more sophisticated in case of a fault concerning actuators because their replacement by a computational algorithm is impossible. As a remedy, the idea of virtual actuators is proposed, which boils down to using the nominal controller and the modifying the control strategy of all actuators (including faulty ones) in such a way as to compensate the fault effect. Nowadays, the existing methods are dedicated mainly to sensor and actuator only, while in case of a process fault (e.g., a leakage in a tank) cannot provide expected results.

The main objective of this paper is to present selected results in the area of actuator and sensor fault-tolerant control for constrained dynamic systems and highlight possible research direction that can be undertaken. The final attention is focused on process faults, which even for linear systems turns into nonlinear estimation problems.

Paper in language: englisch
Date: 13.09 (9:00)

Marcin Witczak

Uniwersytet Zielonogórski
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