Connecting dynamic process simulator with distributed control system using OPC standard

Dynamic simulation can be used e.g. for operator training, automation design and automation testing purposes. For these applications, a flexible connection between a process simulator and distributed control system (DCS) is of great importance. In operator training, it is practical to use the same man machine interface as in the real plant, i.e. the user interface of the DCS, and the same control schemes so that operator can have exactly the same touch to the process as with the real process. Compared to the effort of emulating the graphics of the control system and re-configuring automation solutions for the simulator, this means immense savings. In automation design and testing, there is a need for rapidly testing control strategies and implementation against a simulation model by graphically connecting control variables and measurements to the process model. In this paper, a new framework of connecting automation domain applications is introduced. A case study where dynamic process simulator is connected to the DCS is described, and further requirements of the co-operation between control systems and process simulators are discussed. The framework is based on a new software component, AIC (Application Item Cross Connector) by the aid of which OPC servers of different vendors can be connected together. Through AIC one can connect to two different OPC servers, browse the data items in both servers and create joints between the data items. By giving joining rules, the user can specify the properties of a joint such as frequency, direction, data type, dead band, gain and offset. After the joint is formed, AIC handles the data transmission between the applications. Load and save functions are also provided for, so that the configuration data can be stored into the database. AIC is based on OPC standard 1.0a. An easy to use graphical user interface has also been built for the component. In the case study presented in this paper, the new communication scheme is bench marked by a test system where the OPC servers of a DCS and a dynamic process simulator are connected using AIC. A process model is controlled by using a corresponding automation application in DCS. The framework sets new requirements for the DCS. The most important of these are the capability to save and load the state of the system, to freeze it if needed, and to synchronize the simulator and the DCS. The save and load functionalities are essential for the co-operation with the simulator. Snapshots can be taken from the simulator very easily, so there has to be a way to do the same for the corresponding state in the DCS. These requirements and how to extend current interfaces to meet the needs are also discussed in this paper