A METHOD FOR CONTROLLING A PROCESS PLANT USING A REDUNDANT LOCAL SUPERVISORY CONTROLLER

The present invention discloses a method for controlling a process using a plurality of regulatory controllers (160) connected to a remote supervisory controller (120) over a communication link (155) and to a local supervisory controller (130) over a process bus (170). The remote supervisory controller (120) controls the regulatory controllers (160) over the communication link (155) with the use of a remote process model. During operation of the plant a local process model is configured in the local supervisory controller (130) with control data send on the communication link (155). Upon failure of the communication link (155) the local supervisory controller (130) takes over the control through the process bus (170), acting as a redundant or a backup controller. The method comprises: monitoring transmission of control data between the remote supervisory controller (120) and the plurality of controllers (160) over the communication link (155); determining functional correlations between measured process variables and control process variables, based on the control data and a predetermined correlation function; configuring local process model based on the determined functional correlations; and providing intermediate set points using the configured local process model, upon an intermediate failure of the communication link (155), where the communication link recovers from the intermediate failure within a predetermined time period.