Pump-turbine

A plurality of pump-turbines sharing conduits wherein an upper reservoir-side conduit or a lower reservoir-side conduit is branched in the vicinity of pump-turbines ends, the conduit portions located farther than the branch points are shared among the pump-turbines, the pump-turbines are provided with guide vanes, and there is adopted a multi-stage closing method for the guide vanes such that when a load is rejected, said guide vanes are closed in a relatively rapid manner at the beginning and thereafter shift to a predetermined slow closing at least once, characterized in that at least a first pump-turbine out of the plural pump-turbines is provided with a detector which inputs at least a rotational speed, and when said detector has detected that said first pump-turbine is in a range influenced by an S-characteristic determined by the equation dQ1/dN1>0, where Q1=Q/H, N1=N/H, and wherein Q is turbine discharge, N is rotational speed and H is effective head, a command is issued also to at least one of said plural pump-turbines other than said first pump-turbine to limit the guide vane closing speed to a speed approximately equal to or lower than the speed after the shift to said slow closing in said pump-turbine.

A plurality of pump-turbines sharing conduits wherein an upper reservoir-side conduit or a lower reservoir-side conduit is branched in the vicinity of pump-turbine ends, the conduit portions located farther than the branch points are shared among the pump-turbines, the pump-turbines are each provided with guide vanes, and there is adopted a multi-stage closing method for the guide vanes such that when a load is rejected, said guide vanes are closed in a relatively rapid manner at the beginning and thereafter shift to a predetermined slow closing at least once, characterized in that the plural pump-turbines are each provided with a rotational speed increase detector, and when it is detected that the rotational speed of the associated pump-turbine has exceeded a second predetermined value higher than a rated speed, a command is issued also to each of the other pump-turbines than said pump-turbine to limit the guide vane closing speed to a speed approximately equal to or lower than the speed after the shift to said slow closing.

A plurality of pump-turbines sharing conduits wherein an upper reservoir-side conduit or lower reservoir-side conduit is branched in the vicinity of pump-turbine ends, the conduit portions located farther than the branch points are shared among the pump-turbines, the pump-turbines are each provided with guide vanes, and there is adopted a multi-stage closing method for the guide vanes such that when a full load or a large load close thereto is rejected, the guide vanes are closed in a relatively rapid manner at the beginning and thereafter shift to a predetermined slow closing at least once, characterized in that said plural pump-turbines are each provided with a detector which inputs at least a rotational speed to check whether each pump-turbine is in a range influenced by an S-characteristic determined by the equation dQ1/dN1>0, where Q1=Q/H, N1=NH, and wherein Q is turbine discharge, N is rotational speed and H is effective head, and if the answer is affirmative, a command is issued also to each of the other pump-turbines than said pump-turbine concerned to limit the guide vane closing speed in each said pump-turbine to a speed approximately equal to or lower than the speed after the shift to said slow closing.

A plurality of pump-turbines sharing conduits wherein an upper reservoir-side conduit or a lower reservoir-side conduit is branched in the vicinity of pump-turbine ends, the conduit portions located farther than the branch points are shared among the pump-turbines, the pump-turbines are each provided with guide vanes, and there is adopted a multi-stage closing method for the guide vanes such that when a full load or a large load close thereto is rejected, the guide vanes are closed in a relatively rapid manner at the beginning and thereafter shift to a predetermined slow closing at least once, characterized in that at least a first pump-turbine out of said plural pump-turbines is provided with a rotational speed increase detector, and when it is detected that the rotational speed of said first pump-turbine has exceeded a second predetermined value higher than a rated speed, the guide vane closing speed of the pump-turbine concerned is limited to a speed approximately equal to or lower than the speed after the shift to said slow closing, while a command is issued to at least one of the pump-turbines other than said first pump-turbine to limit the guide vane closing speed in said pump-turbine to a speed approximately equal to or lower than the speed after the shift to said slow closing.

A plurality of pump-turbines sharing conduits wherein an upper reservoir-side conduit or a lower reservoir-side conduit is branched in the vicinity of pump-turbine ends, the conduit portions located farther than the branch points are shared among the pump-turbines, the pump-turbines are each provided with guide vanes, and there is adopted a multi-stage closing method for the guide vanes such that when a full load or a large load close thereto is rejected, the guide vanes are closed in a relatively rapid manner at the beginning and thereafter shift to a predetermined slow closing at least once, characterized in that when it is detected that the rotational speed of at least a first pump-turbine out of the other pump-turbines has exceeded a second predetermined value higher than a rated speed, the guide vane closing speed in the pump-turbine concerned is limited to a speed approximately equal to or lower than the speed after the shift to said slow closing in accordance with the detected signal.

A plurality of pump-turbines sharing conduits wherein an upper reservoir-side conduit or a lower reservoir-side conduit is branched in the vicinity of pump-turbine ends, the conduit portions located farther than the branch points are shared among the pump-turbines, the pump-turbines are each provided with guide vanes, and there is adopted a multi-stage closing method for the guide vanes such that when a full load or a large load close thereto is rejected, the guide vanes are closed in a relatively rapid manner at the beginning and thereafter shift to a predetermined slow closing at least one characterized in that when at least a first pump-turbine out of said plural pump-turbines is following at least an S-characteristic determined by the equation dQ1/dN1>0, where Q1=Q/H, N1=NH, and wherein Q is turbine discharge, N is rotational speed and His effective head, in a flow rate decreasing direction the guide vane closing speed in at least one of said plural pump-turbines other than said first pump-turbine is also limited to a speed approximately equal to or lower than the speed after the shift to said slow closing.

A plurality of pump-turbines sharing conduits wherein an upper reservoir-side conduit or a lower reservoir-side conduit or a lower reservoir-side conduit is branched in the vicinity of pump-turbine ends, the conduit portions located farther than the branch points are shared among the pump-turbines, the pump-turbines are each provided with guide vanes, and there is adopted a multi-stage closing method for the guide vanes such that when a full load or a large load close thereto is shut down, the guide vanes are closed in a relatively rapid manner at the beginning and thereafter shift to a predetermined slow closing at least once, characterized in that there is provided an S-characteristic descent detector for detecting that at least a first pump-turbine out of said plural pump-turbines is following at least an S-characteristic determined by the equation dQ1/dN1>0, where Q1=Q/H, N1=NH, and wherein Q is turbine discharge, N is rotational speed and H is effective head, in a flow rate decreasing direction and upon operation of said S-characteristic decent detector, a command is issued to at least one of said plural pump-turbines other than said first pump-turbine to limit the guide vane closing speed in said pump-turbine to a speed equal to or lower than the speed after the shift to said slow closing.