HydroStab represents a functional box built in Scilab language, in the HYDROTUR
software suite, and is dedicated
to calculating the stability of a speed governor controlling a hydroelectric
machine of the FRANCIS, KAPLAN, PELTON type.
HydroStab Solution provides the adjustment parameters of a series-parallel PID
corrector allowing the operation
of a hydroelectric unit, with a safety margin, and without divergence when
commissioning the regulator on site.
Prior to the study, an Excel CALTUR sheet establishes a reduction of the
hydraulic diagram,
in accordance with the data from the plant (length of pipes per section,
adjoining sections),
and determines the equivalent length and section of a single group.
These results are then to be entered in HydroStab.
HydroStab then determines a convergence domain to be reached
and provides a quadruplet (K p , T i , T d , K d ), with graphical program
proof.
The main method adopted is based on a mathematical technique based on the
Nyquist space, and proposes
to force the passage of the transfer function in open loop, by a point P,
to guarantee a gain margin of 6 dB, with a fixed module margin ma=0.42.
This value is generally commonly accepted in the turbomachinery adjustment
system,
and is recommended by Electricité de France.
HydroStab complies with international standards IEC 60308 and 61362 in the
calculated results.
Other methods (Ziegler-Nichols, Takahashi) are also integrated into HydroStab
for comparative studies.
