Power supply arrangement for direct electrical heating of a pipeline system
In a power supply arrangement for supplying electrical power to the pipeline, the power supply arrangement for direct electrical heating of a pipeline system has basically a three phase transformer, a symmetrization unit, and a compensation unit. The three phase transformer is adapted to support a single phase load connected between a first and a second phase of the transformer. The transformer has at least one first tap changer at a high voltage side of the transformer. The symmetrization unit has a first capacitor connected between the first phase and a third phase of the transformer and an inductor connected between the second phase and the third phase of the transformer. The compensation unit has a second capacitor connected between the first phase and the second phase of the transformer. The first tap changer, the first capacitor, the second capacitor and the inductor are adapted to be varied on-load.
1. A power supply arrangement for direct electrical heating of as pipeline system comprising:
a three phase transformer adapted to support a single phase load connected between a first phase and a second phase of the transformer, said transformer comprising at least one first tap changer at a high voltage side of the transformer;
a symmetrization unit comprising both (a) a first capacitor means and (b) at least one first additional capacitor in parallel with the first capacitor means connected between the first phase and a third phase of the transformer and an inductor means connected between the second phase and the third phase of said transformer; and
a compensation unit comprising both (a) a second capacitor means and (b) at least one second additional capacitor in parallel with the second capacitor means connected between the first phase and the second phase of the transformer, and
a control unit adapted to automatically control voltage levels of said first tap changer, capacitance of said first capacitor means and said second capacitor means and inductance of said inductor means,
wherein automatically controlling the capacitance of said first capacitor means comprises switching the at least one first additional capacitors using at least one corresponding first vacuum contactor, and automatically controlling the capacitance of said second capacitor second comprises switching the at least one second additional capacitors using at least one corresponding second vacuum contactor.
2. The power supply arrangement according to claim 1 , wherein the three phase transformer further comprises at least one second tap changer.
3. The power supply arrangement according to claim 1 , wherein the inductance of the inductor means is adapted to be changed on-load using a third tap changer.
4. The power supply arrangement according to claim 1 , wherein at least one of the transformer, the first capacitor means, the second capacitor means, the inductor means, the first additional capacitor, the second additional capacitor, and the vacuum contactor are dry-type.
5. The power supply arrangement according to claim 1 , further comprising at least one first measuring unit to measure the single phase load parameters and at least one second measuring unit to measure the three phase load parameters.
6. The power supply arrangement according to claim 5 , wherein the load parameters measured are selected from: a cable power factor, voltage, current.
7. A pipeline system comprising a power supply arrangement with,
a three phase transformer adapted to support a single phase load connected between a first phase and a second phase of the three phase transformer,
a first tap changer connected to a high voltage side of the three phase transformer,
a symmetrization unit comprising a first capacitor means connected between the first phase and a third phase of the transformer and an inductor means connected between the second phase and the third phase of said three phase transformer,
a compensation unit comprising a second capacitor means connected between the first phase and the second phase of the three phase transformer,
a first measurement unit connected between the first capacitor means and the three phase transformer and configured to measure at least one three phase load parameter selected from the group consisting of a cable power factor, a voltage, and a current,
a second measurement unit connected between the second capacitor means and the single phase load and configured to measure at least one single phase load parameter selected from the group consisting of a cable power factor, a voltage, and a current, and
a control unit adapted to receive the measured at least one three phase load parameter and the measured at least one single phase load parameter, and based on the received load parameters, automatically control said first tap changer, first capacitor means, second capacitor means and inductor means.
8. The pipeline system according to claim 7 , wherein the control unit is the Programmable Logic Controller controlled from on-site or a remoter location which performs the automatic control.
9. The pipeline system according to claim 7 , wherein the load parameters measured are selected from: a cable power factor, voltage, current.
10. The pipeline system according to claim 7 , further comprising a remote control panel for controlling the power supply arrangement.
11. The pipeline system according to claim 7 , wherein the transformer comprises a plurality of tap positions on the high voltage side and a plurality of tap positions on the low voltage side.
12. The pipeline system according to claim 7 , wherein at least one of the first and second capacitor means comprise a capacitor wherein capacitive values of further capacitors are controlled by switching additional smaller capacitor units.
13. The pipeline system according to claim 12 , wherein the additional capacitors are switched using vacuum contactors.
14. The pipeline system according to claim 7 , wherein the inductance of the inductor means is controlled by changing taps using an on-load tap changer.
15. The pipeline system according to claim 7 , wherein the transformer, the first capacitor means, the second capacitor means, the inductor means, the first additional capacitor, the second additional capacitor and the vacuum contactor are dry-type.