Apparatus and method for improved power flow control in a high voltage network

1. An apparatus for controlling a power flow in a high voltage network, the apparatus comprising:

a phase shifting transformer comprising a tap changer;

a controlled series compensator comprising a controllable reactance unit, the controllable reactance unit comprises a controllable capacitive unit; and

a control unit configured to control the phase shifting transformer and the controlled series compensator in coordination.

2. The apparatus according to claim 1 , wherein the controllable capacitive unit comprises at least one unit including a capacitor device in parallel connection with a thyristor switch.

3. The apparatus according to claim 1 , wherein the controllable capacitive unit comprises at least one unit including a first branch comprising a capacitive device and a second branch connected in parallel to the first branch including a thyristor switch.

4. The apparatus according to claim 3 , wherein the second branch comprises an inductor device connected in series with the thyristor switch.

5. The apparatus according to claim 1 , wherein the control unit comprises a computer including a processor and memory and a sensor for sensing the power flow of the network.

6. The apparatus according to claim 1 , wherein the control unit comprises a loop for controlling the controlled series compensator.

7. The apparatus according to claim 1 , wherein the control unit comprises a loop for controlling the phase shifting transformer.

8. The apparatus according to claim 1 , wherein the control unit comprises a unit for introducing control parameter values.

9. The apparatus according to claim 1 , wherein the phase shifting transformer is positioned at a first location and the controlled series compensator is positioned at a second location and wherein the first location and the second location are separated by a distance.

10. The apparatus according to claim 1 , further comprising:

a shunt compensator.

11. The apparatus according to claim 10 , wherein the control unit comprises a shunt compensator control unit configured to control the shunt compensator.

12. A method for controlling a power flow in a high voltage network comprising a control apparatus including a phase shifting transformer, the method comprising:

adjusting in a first period of time the reactance of the control apparatus by adjusting a capacitance of a capacitive unit which is part of a controlled series compensator; and

adjusting in a second period of time the voltage of the phase shifting transformer and the reactance of the control apparatus to achieve a favorable working balance between the phase shifting transformer and the controlled series compensator.

13. The method according to claim 12 , wherein the controlled series compensator adjustment comprises sensing the power flow, comparison with a set value, adjustment by a PI-controller and comparison with a oscillation damping signal.

14. The method according to claim 12 , wherein the phase shifting transformer adjustment comprises filtering a control signal from the controlled series compensator adjustment, comparison with a reactance set value and adjustment by a PI-controller.

15. A computer program product, comprising:

a computer readable medium; and

computer program instructions recorded on the computer readable medium and executable by a processor for carrying out a method for controlling a power flow in a high voltage network comprising a control apparatus including a phase shifting transformer, the method comprising adjusting in a first period of time the reactance of the control apparatus by adjusting a capacitance of a capacitive unit which is part of a controlled series compensator, and adjusting in a second period of time the voltage of the phase shifting transformer and the reactance of the control apparatus to achieve a favorable working balance between the phase shifting transformer and the controlled series compensator.

16. The computer program product according to claim 15 , wherein the computer program instructions are further for providing the computer program instructions at least in part over a network.

17. The computer program product according to claim 15 , wherein the computer program instructions are further for providing the computer program instructions at least in part over the Internet.