Dynamic Modelling and Simulation
At the heart of a typical ISC project is our capability in Dynamic Modelling and Simulation, whether derived from first principles or plant data. We use high-fidelity, properly validated models to provide our clients with answers to "what-if" questions. Such models give confidence that design and/or operational changes will perform to the required specification.
ISC's modelling capability covers:
- Development of Nonlinear Dynamic Models for Simulation - The model captures the behaviour of the plant/process, in a level of detail that is appropriate for the refinement of the controller that is to be designed. ISC's preferred or recommended model type is usually a grey-box model.
- Derivation of Control-Oriented Models - In the case of a model-based controller e.g. model-based predictive control (MPC), a model with specific structure is a direct element within the controller. In the general case, for example a PID controller, the second-order model can be used in the design of the controller, e.g. to ensure specified gain- and phase-margins are met. These models can be obtained through either analytical derivation or system identification.
- Use of Simulation for Virtual Commissioning of Control Software - During the development of the main control software application, a software emulation of the physical system can be built to replicate the operating modes and anything that requires testing (e.g. ability to inject faults as defined in the System Test Specification). The ability to extensively test software ( either during development or for later revisions or bug fixes) without the need to access the physical system or the real-time target can be very helpful, as testing on the real system is often limited. Read more ...
At ISC we use our considerable experience in modelling the behaviour of a diversity of systems and processes and work closely with our clients to solve their problems.
We help clients understand the developed model to the depth they require, including providing training if appropriate. We can work with clients to explore the "what-if" questions as part the design team meetings. In the case wheere the end-user does not wish to purchase a simulation package, and instead just needs to use the model, we can even provide standalone simulations.
Our engineers utilise a wide variety of modelling packages such as MATLAB/Simulink, LabVIEW and CD&SIM Toolkit, and Hysys. We can also undertake re-coding of legacy models into new modelling packages, including model conversion from Simulink to LabVIEW.
- Simulation of Membrane Filtration Package for Offshore Oil Platform - ISC developed a first principles model of this novel process for use on an offshore oil platform. This was to de-risk and refine the process design as it went through the design and factory testing phases, so that our client had much greater confidence of the system working properly as it moved to final commissioning and use. The model was able to replicate system operation in all expected produced water flow rates and quality, and we were able to refine recommended operational procedures, control strategy and loop tuning. (Download Presentation note)
- Standalone Hands-on Exercises for Upstream Process Control Training ISC developed new, user friendly hands-on for its Upstream Process Control Course. These used existing or newly developed process models for seperators, gas turbines and compressors, to give examples that focussed on the learing.
- Analysis of Hydraulic Damping for a Launch and Recovery A-frame Modelling exercise to analyse the hydraulic damping within a launch and recovery A-frame, to allow proposed system changes to be reviewed to ensure they would deliver the intended improvements on the vessel.
- Assessment of Process Changes - A chemical company wanted to greatly reduce the size of a mixing vessel to minimise waste when changing recipes. A dynamic model was built to assess the viability of level control and the impact on composition and wider process operations. (Download project note)
- Main Oil Line Pump Instability - Offshore oil production was modelled using Hysys.Plant. The source of unacceptable pump speed variability was proven to be a combination of a constraint within the controller and the error-squared mode of operation. (Download project presentation)
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