Abstract: A method for controlling operations of hydraulic machines, in which two or more hydraulic machines are positioned in water conduits separated or branched upstream thereof with the branch water conduits downstream therefrom being joined together or maintained separate. Thus, these hydraulic machines are communicated with each other through the branch water conduits. In this method, the lower limit of a closing operational speed of guide vanes in one hydraulic machine is preferentially or overridingly controlled in the transient phase of operation, by detecting the closing operational speed of guide vanes of the other hydraulic machines. As a result, an abnormal condition in hydraulic pressure in upstream or downstream water conduits may be prevented, which condition would be caused in the event that the operational conditions of respective hydraulic machines are abruptly changed one after another.

Abstract: Provided is a method of controlling a by-pass valve in which the discharge valve is opened or closed in an interlocked relation woth a turbine flow regulating means such as wicket gates of a water-turbine in order to bypass a stream of water with respect to the turbine in synchronism with the movement of wicket gates, thereby decreasing pressure fluctuation in a penstock of the turbine during transient conditions of operation, and is eventually closed when the wicket gates are held in an equilibrium state, thereby eliminating prolonged wasting of the available water.

Abstract: An automatic control apparatus comprises a means for detecting deviation of an actual value from a target value of a controlled quantity for the control operations and a damping feedback means, at least one of which means is provided with an element having a saturation characteristic. Predetermined relations are established between the input value to saturate the output of the detector means and the input value to saturate the output of the damping feedback means to thereby enhance mainly the response of operation for the control in one direction, while for the control operation in the other direction, stability is improved.