Controlled series compensator and method
A control apparatus for a controlled series compensator including a plurality of reactance elements each having a rapid switch for connecting and disconnecting the reactance in series with an electric power transmission line. The apparatus also includes a steady state power flow controller. A damping controller is provides on the presence of an oscillation on the transmission line a first reactance insertion on the transmission line having a first duration of time trigged by a time instant that coincides with a peak in the power oscillation.
1. A control apparatus for a controlled series compensator, the apparatus comprising:
a plurality of reactance elements, each having a rapid switch for connecting and disconnecting a reactance in series with an electric power transmission line,
a steady state power flow controller configured to monitor active power and detect oscillations of power transmitted on the power transmission line, and
a damping controller providing on the presence of a power oscillation on the transmission line a first reactance insertion on the transmission line having a first duration of time trigged at a time instant that coincides with a peak in the power oscillation.
2. The apparatus according to claim 1 , wherein the first duration comprises half a period of the oscillation frequency.
3. The apparatus according to claim 1 , wherein the damping controller is arranged to provide a second reactance insertion following the first reactance insertion.
4. The apparatus according to claim 3 , wherein the second reactance insertion comprises a predetermined level of compensation.
5. The apparatus according to claim 1 , further comprising:
a transient controller providing third reactance in presence of a transient in the active power on the transmission line.
6. The apparatus according to claim 5 , wherein the third reactance is arranged to be trigged by a positive time-derivative of the line power magnitude at the controlled series compensator location leading to a rapid change in line power.
7. The apparatus according to claim 5 , wherein the third reactance is arranged to be trigged by a remote signal.
8. A method for controlling a controlled series compensator on an electric power transmission line, the method comprising:
sensing continuously an active power through the controlled series compensator,
inserting on detecting an oscillation in the active power on the transmission line a first reactance having a first magnitude during a first period of time, and
inserting during a second period of time following the first period of time a second reactance having a second magnitude,
wherein the first reactance insertion is trigged at a time instant coinciding with a peak in the power oscillation.
9. The method according to claim 8 , wherein the first period of time comprises half a period of the oscillating frequency.
10. The method according to claim 8 , wherein average and oscillatory components of the line active power is are separated using a real-time estimation routine.
11. The method according to claim 10 , wherein the estimation routine comprises a recursive least squares algorithm.
12. The method according to claim 11 , wherein the algorithm utilizes an expected oscillation frequency when no oscillations are at hand.
13. The method according to claim 8 , wherein the first reactance magnitude is determined from local measurements at the apparatus location, and the second reactance value comprises a predetermined value.
14. The method according to claim 8 , wherein the necessary reactance magnitude insertions are determined by knowledge of system parameters according to a model of the transmission system.
15. The method according to claim 14 , wherein the parameters of the system model are estimated continuously by a controller.
16. The method according to claim 8 , further comprising:
inserting a third reactance in presence of a transient in the active power on the transmission line.
17. The method according to claim 16 , wherein the insertion of the third reactance is trigged by a positive time-derivative of the line power magnitude at the controlled series compensator location leading to a rapid change in line power.
18. A computer program product, comprising:
a non-transitory computer readable medium; and
computer program instructions recorded on the computer readable medium and executable by a processor to carry out a method for controlling a controlled series compensator on an electric power transmission line, the method comprising sensing continuously an active power through the controlled series compensator, inserting on detecting an oscillation in the active power on the transmission line a first reactance having a first magnitude during a first period of time, and inserting during a second period of time following the first period of time a second reactance having a second magnitude, wherein the first reactance insertion is trigged at a time instant coinciding with a peak in the power oscillation.
19. The computer program product according to claim 18 , wherein the computer program instructions are further for proving the computer program instructions at least in part over a network.
20. A computer program product according to claim 18 , wherein the network is the Internet.