Method for determining a droop response profile of an electrical machine connected to an electrical grid

Abstract

A method for determining a droop response profile of a rotating electrical machine supplying electricity to an electrical network having a network frequency varying on either side of a nominal frequency, wherein a measured rotational speed value and droop response parameters are defined. The droop response profile is a graph centered on the coordinates ([X5; Y5]) of an origin point between 99% and 101% of the measured speed value and defined by at least two coordinate points ([X4,Y4], [X0, Y0]) in the case of over-speed, each of the points having as abscissa a speed value as a percentage of the measured speed value, and for ordinates a filtered speed value as a percentage of the measured speed value modulated by at least one of the droop response parameters.

We claim: 
     
         1 . A method for determining a droop response profile of a rotating machine supplying electricity to an electrical network having a network frequency varying on either side of a nominal frequency, wherein a measured speed value (Vm) of the rotation of the rotating machine corresponding to the frequency of the electrical network and wherein response parameters to the measured speed value are defined, characterized in that the profile is a graph centered on a coordinate point of origin ([X5; Y5]) between 99% and 101% of the measured speed value and defined by at least two coordinate points ([X4; Y4], [X0; Y0]) in case of under-speed and by at least two coordinate points ([X6; Y6], [X10; Y10]) in case of over-speed, each point having a speed value as a percentage of the measured speed value, and for ordinates a speed value filtered as a percentage of the measured speed value modulated by at least one of the response parameters, the response parameters comprising at least a high dead band (BMH) value and a low dead band (BMB) value on either side of the point of origin ([X5;Y5]), a low droop, a median droop, and a high droop (SB, SM, SH) of the rotating machine, a low and a high droop limit value (LSB, LSH), at least one dead band output mode (SBM 1 , SBM 2 , SBM 3 ), and a low and a high breaking point (PCB, PCH) of a nonlinear droop. 
     
     
         2 . The method of  claim 1 , wherein the coordinates ([X4; Y4]) of a first point in the case of under-speed correspond to the low dead band value and have an abscissa (X4) equal to subtraction of 100% of the measured speed value with the low dead band value, and for ordinates (Y4) equal to 100% of the measured speed value. 
     
     
         3 . The method of  claim 2 , wherein a median droop gain (GSM) value and a low droop gain (GSB) value correspond to a ratio between the intrinsic droop of the rotating machine and, respectively, the median droop (SM) and the low droop (SB). 
     
     
         4 . The method of  claim 3 , wherein coordinates ([X3; Y3]) of a second point in the case of under-speed correspond to the output of the dead band as a function of the at least one dead band output mode (SBM), the low limit droop (LSB) value, the low dead band (BMB) value, the median droop gain (GSM) value, and the low breaking point (PCB) value. 
     
     
         5 . The method of  claim 4 , wherein coordinates ([X2; Y2]) of a third point in the case of under-speed correspond to the low breaking point of the nonlinear droop as a function of the coordinates of the second point ([X3;Y3)], the low breaking point (PCB) value, the low droop limit (LSB) value, and the median droop gain (GSM) value. 
     
     
         6 . The method of  claim 5 , wherein coordinates ([X1; Y1]) of a fourth point in the case of under-speed correspond to the low droop limit value as a function of the coordinates of the third point ([X2; Y2]) and the low droop gain (GSB) value. 
     
     
         7 . The method of  claim 6 , wherein coordinates ([X0; Y0]) of a fifth point in the case of under-speed correspond to a limit point of the response profile as a function of the coordinates of the fourth point ([X1; Y1]) and the low droop limit (LSB) value. 
     
     
         8 . The method of  claim 7 , wherein coordinates ([X6; Y6]) of a first point in the case of an over-speed correspond to the high dead band value and have the abscissa (X6) equal to the addition of 100% of the measured speed value to the high dead band (BMH) value, and for ordinate (Y6) equal to 100% of the measured speed value. 
     
     
         9 . The method of  claim 8 , wherein the high droop gain (GSH) value corresponds to a ratio between the intrinsic droop of the rotating machine and the high droop (SH). 
     
     
         10 . The method of  claim 9 , wherein coordinates ([X7; Y7]) of a second over-speed point correspond to the output of the dead band as a function of the dead band output mode (SBM), the high droop limit value (LSH), the high dead band (BMH) value, the high droop gain (GSH) value, and the high breaking point (PCH) value. 
     
     
         11 . The method of  claim 10 , wherein coordinates ([X8; Y8]) of a third over-speed point correspond to the high breaking point of the non-linear droop as a function of the coordinates of the second point ([X7; Y7]) of the high breaking point (PCH) value, the high droop limit (LSH) value, and the median droop gain (GSM) value. 
     
     
         12 . The method of  claim 11 , wherein coordinates ([X9; Y9]) of a fourth over-speed point correspond to the high droop limit value as a function of the coordinates of the third point ([X8; Y8]), the high droop limit (LSH) value, and the high droop gain (GSH) value. 
     
     
         13 . The method of  claim 12 , wherein coordinates ([X10; Y10]) of a fifth point in over-speed correspond to a limit point of the response profile as a function of the coordinates of the fourth point ([X9; Y9] and the high droop limit (LSH) value. 
     
     
         14 . The method of  claim 1 , wherein the low dead band (BMB) value is between 0.02% and 6% of the measured speed value (Vm). 
     
     
         15 . The method of  claim 1 , wherein the high dead band (BMH) value is between 0.02% and 1% of the measured speed value (Vm). 
     
     
         16 . The method of  claim 1 , wherein the median droop (SM) value, the low droop (SB) value, and the high droop (SH) value are between 2% and 20% of the measured speed value (Vm). 
     
     
         17 . The method of  claim 1 , wherein the low breaking point (PCB) value and the high breaking point (PCH) value of the non-linear droop are selected from 0% to 10% of the measured speed value. 
     
     
         18 . The method of  claim 1 , wherein the low droop limit (LSB) value is between 96% and 100% of the filtered speed value. 
     
     
         19 . The method of  claim 1 , wherein the high droop limit (LSH) value is between 100% and 104% of the filtered speed value. 
     
     
         20 . The method of  claim 1 , wherein the at least one dead band output mode (SBM) is selected from the group comprising a first output mode (SBM 1 ) in which, once a dead band extreme value has been reached, the filtered speed reaches the speed defined by the droop, a second output mode (SBM 2 ), in which, once the deal band extreme value has been reached, the filtered speed is defined by the droop while maintaining a constant offset of the dead band proportional to the measured speed value, and a third output mode (SBM 3 ), in which, once the extreme value of the dead band has been reached, the filtered speed joins the speed defined by the droop while following a ramp equivalent to a 2% droop.