Wind power installation and method of operating it
View Patent ↗The purpose of the invention is to reduce the contribution of wind power installations to frequency errors on the grid, and preferably to contribute to the elimination of such errors. Thus, the method involves the use of PID control and/or control with hysteresis so as to regulate the active power injected into the grid, in view of the deviation between a measured grid frequency and the nominal grid frequency.
1. A method of operating a wind power installation connected to a network for distribution of electrical power, said wind power installation comprising at least one wind power generator, said wind power installation being related to said network for injection of power into said network, said network having a nominal network frequency (f n ) and said network being arranged for operating at the nominal network frequency, wherein said method comprises controlling the active power that is injected into said network from said wind power installation in view of a measured actual network frequency (f a ) at which said network is operating, said method comprising the steps of:
measuring the actual network frequency (f a ); and
determining a difference (E) between the actual network frequency (f a ) and the nominal network frequency(f n );
said method further comprising the step of, if said difference (E) is larger than a predefined threshold, adapting by means of a controller the amount of active power that is injected into said network from said wind power installation, in a manner that depends on a magnitude of the difference (E), a duration of the difference (E), and a rate of change of the controller output so as to bring the actual network frequency (f a ) back towards the nominal network frequency (f n ).
2. Method according to claim 1 , wherein the active power that is injected into said network is adapted using said controller involving at least an integration over time of the difference (E) between the actual network frequency (f a ) and the nominal network frequency (f n ).
3. Method according to claim 2 , wherein said controller is a PI controller.
4. Method according to claim 2 , wherein said controller is a PID controller.
5. Method according to claim 2 , wherein said controller is an I controller.
6. Method according to claim 2 , wherein said controller is an ID controller.
7. Method according to claim 1 , wherein the active power that is injected into said network is adapted using said controller involving at least a time derivative of the difference (E) between the actual network frequency (f a ) and the nominal network frequency (f n ).
8. Method according to claim 7 , wherein said controller is an ID controller.
9. Method according to claim 7 , wherein said controller is a PID controller.
10. Method according to claim 7 , wherein said controller is a D controller.
11. Method according to claim 7 , wherein said controller is a PD controller.
12. A method of operating a wind power installation connected to a network for distribution of electrical power, said wind power installation comprising at least one wind power generator, said wind power installation being related to said network for injection of power into said network, said network having a nominal network frequency (f n ) and said network being arranged for operating at said nominal network frequency, wherein said method comprises controlling the active power that is injected into said network from said wind power installation in view of a measured actual network frequency (f a ) at which the network is operating, said method comprising the steps of
reducing the active power injected into said network, as a function of the actual network frequency, if the actual network frequency increases beyond a first upper network frequency threshold value (f 1 ); and
stopping injection of active power into said network if the actual network frequency increases beyond a second upper network frequency threshold value (f 2 ) higher than the first upper frequency threshold value (f 1 ),
wherein
once the actual network frequency has increased beyond the second upper network frequency threshold value (f 2 ), injection of active power into said network is not resumed until the actual network frequency has decreased below a third upper frequency threshold value(f 3 ) lower than the second upper frequency threshold value (f 2 ).
13. Method according to claim 12 , wherein said method further comprises the steps of:
reducing the active power injected into said network, as a function of the actual network frequency, if the actual network frequency decreases below a first lower network frequency threshold value (f 4 ); and
stopping injection of active power into said network if the actual network frequency decreases below a second lower network frequency threshold value (f 5 ) lower than the first lower frequency threshold value (f 4 ), wherein, once the actual network frequency has decreased below the second lower network frequency threshold value (f 5 ), injection of active power into said network is not resumed until the actual network frequency has increased beyond a third lower frequency threshold value (f 6 ) higher than the second lower frequency threshold value (f 5 ).
14. Method according to claim 12 , wherein said method further comprises the step of increasing the active power injected into said network, as a function of the actual network frequency, if the actual network frequency decreases below a first lower network frequency threshold value (f 4 ).
15. Method according to claim 14 , further comprising the step of stopping injection of active power into said network if the actual network frequency decreases below a second lower network frequency threshold value (f 5 ) lower than the first lower frequency threshold value (f 4 ), wherein, once the actual network frequency has decreased below the second lower network frequency threshold value (f 5 ), injection of active power into said network is not resumed until the actual network frequency has increased beyond a third lower frequency threshold value (f 6 ) higher than the second lower frequency threshold value (f 5 ).
16. Method of claim 12 , further comprising the method of operating a wind power installation connected to a network for distribution of electrical power, said wind power installation comprising at least one wind power generator, said wind power installation being related to said network for injection of power into said network, said network having a nominal network frequency (f n ) and said network being arranged for operating at the nominal network frequency, wherein said method comprises controlling the active power that is injected into said network from said wind power installation in view of a measured actual network frequency (f a ) at which said network is operating, said method comprising the steps of:
measuring the actual network frequency (f a ); and
determining a difference (E) between the actual network frequency (f a ) and the nominal network frequency (f n ),
said method further comprising the step of, if the difference is larger than a predefined threshold, adapting the amount of active power that is injected into said network from said wind power installation, in a manner so as to bring the actual network frequency (f a ) back towards the nominal network frequency (f n ).
17. Wind power installation arranged to be connected to a network for distribution of electrical power, said wind power installation comprising at least one wind power generator, said wind power installation being related to said network for injection of power into said network, wherein
said wind power installation comprises a control system arranged for controlling the injection of active power into said network depending on the magnitude of the difference (E), the duration of the difference (E), and the rate of the change of the controller output in accordance with the method of claim 1 .