Auxiliary power supply with a coupling capacitor between a high voltage line and ground
View Patent ↗A power supply apparatus includes a coupling capacitor arranged to be connected on its first end to ground; a transformer including a primary winding and a secondary winding; a first rectifier bridge connected in parallel with the secondary winding; and an energy storage, to which a load is arranged to be connected. The primary winding is arranged to be connected between a second end of the coupling capacitor and a high voltage transmission line such that all current between the second end of the coupling capacitor and the high voltage transmission line passes through the primary winding. The energy storage is arranged to be charged by means of a current passing through the first rectifier bridge. Furthermore, the power supply apparatus includes a bypasser. A corresponding three-phase apparatus is also presented.
1. A power supply apparatus comprising:
a coupling capacitor arranged to be connected on a first end thereof to ground;
a transformer comprising a primary winding and a secondary winding;
a first rectifier bridge connected in parallel with said secondary winding; and
an energy storage element, to which a load is arranged to be connected;
a bypasser including:
a second rectifier bridge connected in parallel with said primary winding;
a first transistor connected with a collector and emitter thereof in parallel with said second rectifier bridge; and
a controller;
wherein said primary winding is connected between a second end of said coupling capacitor, and a high voltage transmission line such that when the bypasser is not activated, substantially all current between said second end of said coupling capacitor and said high voltage transmission line passes through said primary winding;
said energy storage element charged by current passing through said first rectifier bridge.
2. The power supply apparatus according to claim 1 , wherein said power supply apparatus is connected to a high voltage transmission line with a rated line voltage ranging from about 110 kV to about 800 kV rms line-to-line.
3. The power supply apparatus according to claim 1 , wherein said coupling capacitor is arranged to be galvanically connected to ground.
4. The power supply apparatus according to claim 1 , wherein said energy storage element is connected in parallel with said first rectifier bridge.
5. The power supply apparatus according to claim 1 , wherein said controller is arranged to continuously control said first transistor.
6. The power supply apparatus according to claim 1 , wherein said controller is arranged to switch in and out said first transistor with a duty cycle that is several periods of a network frequency.
7. The power supply apparatus according to claim 1 , wherein said controller is located on a secondary winding side, and command signals are transferred from said controller to said first transistor via an optocoupler.
8. The power supply apparatus according to claim 1 , further comprising an over-voltage limitation means which is independent of command signals to said first transistor.
9. The power supply apparatus according to claim 8 , wherein said over-voltage limitation means comprises a zener diode.
10. The power supply apparatus according to claim 1 , further comprising:
a plurality of said transformers;
wherein each of said plurality of transformers comprises:
a primary winding circuit, comprising said primary winding, said second rectifier bridge and said first transistor; and
a secondary winding circuit, comprising said secondary winding, said first rectifier bridge and said energy storage element; and
all primary windings of said plurality of transformers are connected in a serial connection.
11. The power supply apparatus according to claim 10 , further comprising:
a protection capacitor connected in parallel with said serial connection of primary windings;
a resistor connected in series with said parallel connection of said protection capacitor and said serial connection of primary windings; and
a varistor connected in parallel between said serial connection of said resistor and said parallel connection of said protection capacitor and said serial connection of primary windings,
wherein said varistor is connected to said coupling capacitor and said varistor is arranged to be connected to said high voltage transmission line.
12. The power supply apparatus according to claim 11 , wherein said resistor is arranged to be connected to said high voltage transmission line and said protection capacitor is connected to said coupling capacitor.
13. The power supply apparatus according to claim 11 , wherein said resistor is connected to said coupling capacitor and said protection capacitor is arranged to be connected to said high voltage transmission line.
14. The power supply apparatus according to claim 1 , further comprising:
one primary winding circuit comprising said primary winding, said second rectifier bridge and said first transistor; and
a plurality of secondary winding circuits, wherein each secondary winding circuit comprises said secondary winding, said first rectifier bridge and said energy storage element;
wherein said first primary winding circuit is coupled to all of said secondary winding circuits in said transformer.
15. The power supply apparatus according to claim 1 , further comprising a second coupling capacitor, and said two coupling capacitors are both connected via a second transformer to ground and via a third transformer to said primary winding.
16. An apparatus comprising:
a power supply apparatus according to claim 1 ,
wherein said first end of said coupling capacitor is connected to ground and said second end of said primary winding is connected to a high voltage transmission line.
17. A three phase power supply apparatus comprising three power supply apparatuses according to claim 1 , wherein each of said three power supply apparatuses is arranged to be connected to a transmission line of respective one of three phases.
18. A power supply apparatus comprising:
a coupling capacitor connected on a first end thereof to ground;
a transformer having a primary winding and a secondary winding;
a first rectifier bridge connected in parallel with said secondary winding; and
an energy storage element, to which a load is arranged to be connected;
said transformer comprising a bypasser such that when operated in a saturation mode, said transformer limits power to said secondary winding of said transformer;
wherein said primary winding is connected directly between a second end of said coupling capacitor without any intervening elements, and a high voltage transmission line such that all current between said second end of said coupling capacitor and said high voltage transmission line passes through said primary winding;
said energy storage element charged by current passing through said first rectifier bridge.
19. A power supply apparatus comprising:
a coupling capacitor connected on a first end thereof to ground;
a transformer comprising a primary winding and a secondary winding;
a first rectifier bridge connected in parallel with said secondary winding; and
an energy storage element, to which a load is arranged to be connected;
a bypasser including controlled semiconductor components arranged as a bidirectional bypass circuit;
said bypasser connected in parallel with said primary winding of said transformer;
wherein said primary winding is connected directly between a second end of said coupling capacitor without any intervening elements, and a high voltage transmission line such that when the bypasser is not activated, substantially all current between said second end of said coupling capacitor and said high voltage transmission line passes through said primary winding;
said energy storage element charged by current passing through said first rectifier bridge.