Method and apparatus for determining a characteristic curve for an electric variable of a wind energy plant

1. A method for determining an adapted characteristic curve ( 9 ) for an electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) of a wind energy plant ( 1 ), wherein the characteristic curve ( 9 ) contains characteristic values of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) depending on different values of a wind (v w ), comprising the steps of:

measuring at least one characteristic value of the electric variable of the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) for at least one value of the wind (v w ) using a measuring device ( 3 );

adapting for the at least one value of the wind (v w ), a characteristic value of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) from a predetermined characteristic curve ( 7 ), containing characteristic values of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) as a function of different values of the wind (v w ), taking into account the characteristic value measured for the at least one value of the wind (v w ), to obtain the adapted characteristic curve ( 9 );

further characterised in that the number (n) of the characteristic values of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) measured for one value of the wind (v w ) is established and the adaptation of the characteristic value is performed depending on the number (n) of the measured characteristic values measured for the respective value of the wind (v w ), and

further characterised in that the characteristic value of the predetermined characteristic curve ( 7 ) and the at least one measured characteristic value are weighted in a calculation of the adapted characteristic value, provided that the number (n) of the characteristic values of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) measured for the respective value of the wind (v w ) is below a limit number.

2. A method according to claim 1 , characterised in that the adapted characteristic value is calculated by calculating a weighted arithmetic mean of the characteristic value of the electric variable (P el , Q, φ, cos φ, I p , I Q ) from the predetermined characteristic curve ( 7 ) and the at least one measured characteristic value, provided that the number (n) of the characteristic values of the electric variable (P el , Q, φ, cos φ, I p , I Q ) measured for the respective value of the wind (v w ) is below the limit number.

3. A method according to claim 1 , characterised in that the measured characteristic value of the electric variable (P el , Q, φ, cos φ, I p , I Q ) enters with the weight

1

n

Ges

into a calculation of the adapted characteristic value, and the characteristic value of the electric variable (P el , Q, φ, cos φ, I p , I Q ) from the predetermined characteristic curve ( 7 ) enters with the weight

n

Ges

-

n

n

Ges

into the calculation of the adapted characteristic value, wherein n is the number of the characteristic values of the electric variable (P el , Q, φ, cos φ, I p , I Q ) measured for the respective value of the wind (v w ), and n Ges is a number for which applies: n Ges ≧n.

4. A method according to claim 3 , characterised in that the number n Ges is equal to the limit number.

5. An apparatus for determining an adapted characteristic curve ( 9 ) for an electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) of a wind energy plant ( 1 ), wherein the characteristic curve ( 9 ) contains characteristic values of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) depending on different value of a wind (v w ), the apparatus comprising:

a measuring equipment ( 3 ), by which at least one characteristic value of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) can be measured for at least one value of the wind (v w ),

an analysing equipment ( 5 ), by which a characteristic value of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) from a predetermined characteristic curve ( 7 ) containing characteristic values of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) as a function of different values of the wind (v w ) is adaptable for the at least one value of the wind (v w ), taking into account the characteristic value measured for the at least one value of the wind (v W )), to obtain the adapted characteristic curve ( 9 );

further characterised in that by the analysing equipment ( 5 ), the number (n) of the characteristic values of the electric variable selected from the group consisting of (P el , Q, φ, cos φ, I p , and I Q ) measured for one value of the wind (v w ) can be established and the adaptation of the characteristic value through the analysing equipment ( 5 ) can be performed depending on the number (n) of the measured characteristic values measured for the respective value of the wind (v w ).

6. An apparatus according to claim 5 , characterised in that the characteristic value of the predetermined characteristic curve ( 7 ) and the at least one measured characteristic value is weighted in a calculation of the adapted characteristic value by the analysing equipment ( 5 ), provided that the number (n) of the characteristic values of the electric variable (P el , Q, φ, cos φ, I p , I Q ) measured for the respective value of the wind (v w ) is below a limit number.

7. An apparatus according to claim 6 , characterised in that the adapted characteristic value is calculable in that a weighted arithmetic mean of the characteristic value of the electric variable (P el , Q, φ, cos φ, I p , I Q ) from the predetermined characteristic curve ( 7 ) and the at least one measured characteristic value is calculable by the analysing equipment ( 5 ), provided that the number (n) of the characteristic values of the electric variable (P el , Q, φ, cos φ, I p , I Q ) measured for the respective value of the wind (v w ) is below the limit number.

8. An apparatus according to claim 5 , characterised in that the measured characteristic value of the electric variable (P el , Q, φ, cos φ, I p , I Q ) enters with the weight

1

n

Ges

into a calculation of the adapted characteristic value, and the characteristic value of the electric variable (P el , Q, φ, cos φ, I p , I Q ) from the predetermined characteristic curve ( 7 ) enters with the weight

n

Ges

-

n

n

Ges

into the calculation of the adapted characteristic value, wherein n is the number of the characteristic values of the electric variable (P el , Q, φ, cos φ, I p , I Q ) measured for the respective value of the wind (v w ), and is a number for which applies: n Ges ≧n.

9. An apparatus according to claim 8 , characterised in that the number n Ges is equal to the limit number.

10. An apparatus according to claim 5 , characterised in that after reaching a limit number of characteristic values of the electric variable (P el , Q, φ, cos φ, I p , I Q ) measured for one value of the wind (v w ), the characteristic value of the predetermined characteristic curve ( 7 ) for this value of the wind (v w ) is adaptable by the analysing equipment ( 5 ) in that the arithmetic mean of the measured characteristic values is set-table as the adapted characteristic value for this value of the wind (v w ).