System And Method For Deicing Of Power Line Cables
First Claim
1. A system for deicing and anti-icing operations of AC and DC power transmission lines comprises:
- at least one section of cable for transmission of power in the transmission line comprising at least a first, a second, and a third conductor;
wherein the first, second, and third conductor are mutually electrically insulated along the length of the section but are connected at ends of the section to form a series serpentine path of at least three conductors connected in series; and
at least a first switch at a first end of the section of cable, and at least a second switch at a second end of the section of cable, the first and second switches operable such that the first, second, and third conductor are connected in parallel in a normal mode and operate in series in an anti-icing mode.
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Accused Products
Abstract
A system and method for deicing power transmission cables divides the cable into sections. Switches are provided at each end of a section for coupling the conductors together in parallel in a normal mode, and at least some of the conductors in series in an anti-icing mode. When the switches couple the conductors in series, an electrical resistance of the cable section is effectively increased allowing self-heating of the cable by power-line current to deice the cable; the switches couple the conductors in parallel for less loss during normal operation. In an alternative embodiment, the system provides current through a steel strength core of each cable to provide deicing, while during normal operation current flows through low resistance conductor layers. Backup hardware is provided to return the system to low resistance operation should a cable overtemperature state occur.
242 Citations
24 Claims
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1. A system for deicing and anti-icing operations of AC and DC power transmission lines comprises:
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at least one section of cable for transmission of power in the transmission line comprising at least a first, a second, and a third conductor;
wherein the first, second, and third conductor are mutually electrically insulated along the length of the section but are connected at ends of the section to form a series serpentine path of at least three conductors connected in series; andat least a first switch at a first end of the section of cable, and at least a second switch at a second end of the section of cable, the first and second switches operable such that the first, second, and third conductor are connected in parallel in a normal mode and operate in series in an anti-icing mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 10)
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9. A system for anti-icing operation of power transmission lines comprises:
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at least one cable having at least two sections, wherein each section comprises; at least a first, a second, and a third conductor;
wherein the first, second, and third conductor are mutually insulated;a first switch for coupling the second and third conductors to the first conductor at a first end of the cable, the second and third conductors being electrically coupled near the first switch; a second switch for coupling the first and second conductors to the third conductor at a second end of the cable, the first and second conductors being electrically coupled near the second switch; and wherein the third conductor of the first section is connected to the first conductor of the second section; and a system controller for simultaneously opening the first and second switches of each section to increase resistance of the at least one cable by placing the first, second, and third conductors in series for anti-icing operation of the cable of that section, and wherein the system controller is capable of sequentially opening switches of sections.
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11. A switchbox for switching conductors of a transmission line cable between a parallel configuration and a series configuration, the switchbox comprising:
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an energy storage device for providing power to the switchbox; apparatus for charging the energy storage device; a control signal receiver for receiving switch operation commands, the control signal receiver powered from the energy storage device; at least one switch for determining current flow through at least one conductor of the cable, the switch electrically actuated under control of the control signal receiver; and apparatus for overriding the control signal receiver and placing the cable conductors in a parallel configuration if a high temperature is detected on a conductor of the cable.
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12. A system for deicing of a cable of a power transmission line, the cable comprising N conductors, where N is an odd integer larger than one, where each of the N conductors are electrically insulated from the other conductors the system comprising:
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a first and a second switchbox, wherein the first switchbox is coupled to a first end of the cable and the second switchbox is coupled to a second end of the cable; wherein each switchbox has at least (N−
1)/2 switches;wherein in a first mode the switches of the switchboxes connect all N conductors of the cable in parallel, and in a second mode the switches of the switchboxes connect all N conductors in series to increase cable resistance for effective deicing operations; and a system controller for placing the switchboxes in the first mode for normal operation and in the second mode for deicing the cable. - View Dependent Claims (18)
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13. A system for anti-icing operation of a cable of a power transmission line, the cable comprising a resistive strength core and at least one conductor, the strength core being electrically insulated from the at least one conductor the system further comprising:
a switchbox for diverting sufficient current from the conductor through the resistive strength core for anti-icing operation of the cable in a first operating mode, and wherein a majority of the current passes through the conductor in a second operating mode. - View Dependent Claims (14, 15, 16, 17)
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19. A system for anti-icing of power transmission lines comprises:
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at least one section of cable for transmission of power in the transmission line comprising at least a first, a second, and a third conductor;
wherein the first, second, and third conductor are mutually electrically insulated;at least a first switch at a first end of the section of cable, and at least a second switch at a second end of the section of cable, the first and second switches operable such that the first, second, and third conductor are capable of being connected in at least a low resistance configuration, an intermediate resistance configuration, and a high resistance configuration; and a system controller for determining when anti-icing operation is required, for selecting an appropriate anti-icing configuration from the intermediate and high resistance configurations, and for setting the switches into the anti-icing configuration when anti-icing operation is required, and into the low resistance configuration when anti-icing operation is not required.
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20. A method for deicing a section of a cable of a power transmission line, the cable comprising a plurality of conductors extending between a first switchbox and a second switchbox, the section of cable having a normal operating mode wherein the plurality of conductors are electrically in parallel, the method comprising:
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detecting ice accumulation on the section of the cable; configuring switches of the switchboxes to couple a plurality of the conductors of the cable electrically in series thereby placing the section of cable in a deicing mode having a deicing mode resistance greater than a resistance of the section of cable in the normal operating mode; allowing a current flowing in the section of cable to resistively heat the section of cable to deice the section of cable; and reconfiguring the switches of the switchboxes to return the section of cable to the normal operating mode. - View Dependent Claims (21, 22, 23, 24)
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Specification