Method for detecting wind power plants using a radar system

1. A method for detection of wind power installations using a radar installation, the method comprising:

a) transmitting a number N of predetermined sequences B x of K modulated transmission pulses at a predetermined pulse repetition frequency successively in time, where x=1, . . . , N, wherein after each transmitted sequence a cyclic switching is performed to a different pulse repetition frequency of a predetermined number of pulse repetition frequencies;

b) receiving and processing, by the radar installation, transmission pulses reflected by an object, wherein the processing creates received pulses corresponding to the transmitted pulses, wherein a number R of received pulses are received for each transmission pulse;

c) determining a range to the object using a signal delay-time measurement from the received pulses belonging to the sequences B x of modulated transmission pulses, and producing a range Doppler matrix with R rows and N*K columns;

d) cyclically performing a number M of measurement processes in an azimuth direction in an azimuth range, wherein N sequences B x of modulated transmission pulses are transmitted in the respective azimuth direction for each measurement process, and a range Doppler matrix is produced for each measurement process M;

e) arranging, in sequence using a predetermined correction term, sample values of Z sequences B N of modulated transmission pulses from M measurement processes, where Z=2 . . . N, and processing the arranged sequences, wherein a harmonic oscillation with a least square error with respect to the sample values is calculated using a maximum likelihood estimator;

f) obtaining a result matrix with R rows and N/Z columns from the range Doppler matrix with R rows and N*K columns using the maximum likelihood estimator, wherein the signal strength, phase and Doppler frequency of the object are known for each cell;

g) successively producing two result matrices E 1 , E 2 in time after method steps a)-f), and comparing the two result matrices with one another,

wherein a range Doppler cell is marked as a location of a wind power installation if

i. the signal strength of a range Doppler cell is above a predeterminable threshold value in both result matrices E 1 , E 2 ,

ii. the Doppler frequency shift in a range Doppler cell is within a normal value range for wind power installations in both result matrices E 1 , E 2 , and

iii. the difference between the Doppler frequencies in a range Doppler cell in both result matrices E 1 , E 2 is below a predetermined threshold value.

2. The method as claimed in claim 1 , wherein when the sequences S m (B x ) of sample values from M measurement processes are arranged in sequence, a phase correction of adjacent sequences S m (B x ) of sample values is taken into account, if the adjacent sequences S m (B x ) originate from sample values from different measurement processes, where m=1 . . . M.

3. The method as claimed in claim 2 , wherein the arrangement of the sequences S m (B x ) of sample values from M measurement processes in sequence is carried out as follows:

S 1 (B 1 ), S 1 (B 2 ), . . . , S 1 (B N ), K, S 2 (B 1 ), S 1 (B 2 ), . . . , S 2 (B N ), . . . , K, S M (B 1 ), S M (B 2 ) . . . , S M (B N ),

where K is a phase correction term.

4. The method as claimed in claim 2 , wherein the arrangement of the sequences S m (B x .) of sample values from M measurement processes in sequence is carried out as follows:

S 1 (B 1 ), K, S 2 (B 1 ), K, . . . , K, S M (B 1 ), K, S 1 (B 2 ), K, S 2 (B 2 ), K, . . . , K, S M (B 2 ) K, . . . , K, S 1 (B N ), K, S 2 (B N ), K, . . . , K, S M (B N ),

where K is a phase correction term.

5. The method as claimed in claim 3 , wherein the phase correction term K is used to shift the sampling times of a sequence of successive items such that adjacent sequences S m (B x ) have the same phase.

6. The method as claimed in claim 4 , wherein the phase correction term K is used to shift the sampling times of a sequence of successive items such that adjacent sequences S m (B x ) have the same phase.