Abstract: A master controller receives a load demand and a plurality of plant data from a heat power plant and outputs command signals on at least two of an electric power, a feed water flow rate, a fuel flow rate, an air flow rate and a recirculation gas flow rate of the plant required to achieve the load demand. A plurality of sub-loop controllers independently provided one for each of the command signals provide control quantities for controlling respective control ends in accordance with the command signals. A transmission loop is arranged between the sub-loop controllers and the master controller. Drive means drive the control terminals provided one for each of the control quantities supplied from the sub-loop controllers. An I/O bus is arranged between one of the sub-loop controllers and the drive means driven by the command signal for the one sub-loop controller. Detection means detect the plant data to be delivered to the master controller or the sub-loop controllers.

Abstract: In an automatic control system, controls receive an input indicative of a deviation between feedback and demand signals and produce an output which in turn is applied to a plant to control it. A diagnostic device includes a model having an equivalent characteristic to the controls and receives the deviation signal. When a noise coming into the automatic control system is detected or when a deviation between the outputs of the model and controls is sufficiently small, no model operation is performed, and the output of the controls is determined as that of the model. However, when the deviation between the outputs of the model and the controls is large, the model is supplied with an input thereby performing a model operation. A resultant output of the model is then compared with the output of the controls to produce an alarm indicative of an abnormal state of the controls in accordance with a deviation between these outputs.