Alarms Data Acquisition User interface   Tagging Communications Linux PRISM SCADA   Supervisory Control Short Term Load Forecasting
Supervisory Control Supervisory Control functions normally include remote device control and local device tagging (control inhibits). They are treated as the highest priority activities within the system. These activities normally start with device selection and complete with feedback of status or analog result(s). All control dialogue between the dispatcher and the machine are processed in Motif-styled dialogue boxes. Executed control sequences are logged in the alarm/event files for permanent record. The communication dialogue between the Front End Processor (FEP) and the RTU is normally protected by error detection code as defined by the protocol. The ACS-designed FEP supports both standard BCH and CRC error detection code for communications between the RTU and the FEP, and between the FEP and the communication servers. In addition to error detection code, a message validation technique is employed to check for valid function code, proper channel/RTU address, exact message length, and correct message sequence such as acknowledgment. For control dialogue between the FEP and the RTU, an industry standard select-check-before-operate sequence is implemented. Message encode, decode and re-encoding technique is utilized whenever possible. To guarantee that no false operation will occur due to communication errors, the FEP will retry up to 6 times on the no-reply time-out on the "select" function only. Other control message error(s) will result in immediate cancellation. The operator's procedure to start a control action normally begins with device selection. The graphical user interface software allows the user to define any dynamic element in any display as a valid control target. However the device selection is protected by the Area of Responsibility logic on display selection, and by the Area of Responsibility assigned for each controllable device. A dispatcher's request to retrieve an unauthorized display or to select certain unauthorized control points on an authorized display will be rejected. Optionally, a password or security code can be assigned to a control point. In that case, an authorized operator will not be able to execute a protected device without first entering the proper password or valid security code. The control action is further protected by user–definable control suppression logic. That is, each control point can be blocked for control action based on the status of up to three other user definable status point(s). These status points can either be automatically acquired real status points, or pseudo points updated by the operator. A useful application, for example, is to block supervisory control of a breaker if another status point indicates that the recloser is enabled. A control file, created and modifiable using the Database Editor, is required for each RTU to define the characteristics of all controllable devices. This is needed in addition to the dynamic records for display of associated analog value or status. For each control point various parameters are specified, including point description, RTU/Control-point-ID, contact closure time, control suppression criteria, the demand change(s) expected, and the maximum elapsed time anticipated for completion of control. Incremental control and setpoint control is supported in the standard control process. Special control including gate, var, and multiple step control can be implemented using the Command Interpreter. The Command Interpreter can be scheduled to execute periodically at a user-definable rate, to execute at a specific time, or to be activated by the dispatcher using a selectable display target.
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