6.2　Speed Governing System and Transient Analysis

6.2　Speed Governing System and Transient Analysis

6.2.1　Every unit shall be equipped with a speed governing system composed of speed governor，oil pressure unit and other auxiliary equipment.

6.2.2　The calculations for guaranteed regulation of turbines shall be conducted according to the mode of main electrical connection，the characteristics of both the water conveyance system and the units of the hydropower station，and the operating conditions，and shall meet the following requirements:

1　The maximum guaranteed rate of pressure rise in the turbine spiral case（in front of guide vane for tubular turbine）during load rejection of units should be 70%-100% if the rated head is under 20m；70%-50% if the rated head is 20-40m；50%-30% if the rated head is 40-100m；30%-25% if the rated head is 100-300m；and less than 25% if the rated head is above 300m.

2　The maximum guaranteed rate of the rotational speed rise during load rejection of units should not be larger than 60%，which should not be larger than 65% for tubular turbines，and not larger than 30% for impulse turbines.

6.2.3　The time constant of water flow inertia of the diversion system of the hydropower station，Tw，and the time constant of inertia of the units，Ta，shall meet the requirements of the turbine controlling system.

6.2.4　If the guaranteed rate of pressure rise or rotational speed rise cannot meet the design requirement，the following measures may be taken:(https://www.daowen.com)

1　Revise the rules for closing the guide vane.

2　Increase the rotating inertia of generator.

3　Set up pressure regulating valve；

4　Set up surge chamber.

5　Revise the layout or dimensions of the water pipes.