References
References
ELECTRIC POWER INDUSTRY OF MONTENEGRO, Steam Power Plant Pljevlja, Transportation Control System for Electro Filter Ashes and Cinder

The transportation line for electro filtered ashes and cinder, hydraulically carries the mixture of water, ashes and cinder to a remote dump, 2 km away from the steam power plant.The line starts at the hidromixture reservoir, in which the level of hidromixture is continually and discretely measured (minimal level signal). Two hydraulic pumps provide the transportation, one on the mixture suction side and the other on the mixture suppressing side. The electromotor pump’s power is 220 kW. The pump on the suction side is connected directly to power line, while the pump on the suppressing side is driven by a frequency inverter. Along the line, the states of electro-hydraulic valves are monitored and checked, whether the valves are open or closed, on both the suction and suppressing sides, motor pump currents, pump revolution speed on suppressing side, as well as the hidromixture pressure in the pipeline.The line’s control system functions in two modes: manual and automatic.

In manual mode, all actuator’s drive (valves and pumps) is accomplished by manual commands, over a “touch-screen” panel, but the execution sequence of these operations is defined and conditioned by the program (for instance the condition for pump operation on suppressing side is the nominal level in the reservoir, pressure in the system, then valve openness on the suction side and on the suppressing side, as well as pump functioning on the suction side.)

The automatic mode is initiated by activating a button on the “touch-screen” panel, in case the initial conditions are fulfilled (level in the reservoir, valves in closed position, pumps in good order). Sequentially, and mutually conditioned, all the other line devices are activated: valve on suction side, pump on suction side, after accomplishing the adjusted pressure – the valve on suppressing side and the pump on suppressing side. During operation, states of relevant parameters are monitored (the level in the reservoir, the pressure in the pipeline, working/faulty pump), and it is alarmed, i.e. the process is stopped in case any of the parameters exceeds the allowed range. The sequence of line drives deactivation is also defined by the program. 
The setting of the electromotor pump’s revolution speed on suppressing side, in both manual and automatic operating mode, is issued in one of the two ways (mode selection is performed on the “touch-screen” panel):
the reference is specified to frequency inverter via the "touch-screen" potentiometer 
the reference is calculated by program’s PID algorithm, with feedback connection by hidromixture level in the reservoir.

The line’s control system is implemented with Omron’s PLC and "touch-screen" panel. On panel all devices and installations along the line are displayed, in form of synoptic schematic, followed by animation of instant states (level in the reservoir, valves and pumps state, pressure in the installation).
The operating mode is selected from the panel – manual or automatic. In dependence to the selected operating mode, particular drives are activated, or the automatic sequence is initiated. Also the pump reference setting mode on the suppressing side is selected, as well as the relevant process parameters: the allowed level values in the reservoir and pressure in the installation, the allowed timings during valve opening, as well as PID parameters that regulate the operation of pump on the suppressing side. 
On separate display, alarms of the process are monitored and confirmed. For the system maintenance personnel, a display is defined via which instant states of all input signals can be monitored.

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