WO2002041459A1

WO2002041459A1 - Switching apparatus and method for varying a phase line impedance of an electric power transport line section

Info

Publication number: WO2002041459A1
Application number: PCT/CA2000/001348
Authority: WO
Inventors: Pierre Couture
Original assignee: Hydro-Qhébec
Priority date: 1999-12-03
Filing date: 2000-11-14
Publication date: 2002-05-23

Abstract

The invention concerns a switching apparatus and method for varying the impedance of a phase line of an electric power transport line section. The phase line comprises n electrically conductors isolated from one another and mutually shorted out at two ends of the section. The apparatus comprises, for each of at least one of the n conductors, a passive component and a pair of electromechanical and electronic switches, the pair of switches being adapted to selectively connect and disconnect the passive component in series with the corresponding conductor, the switches of each pair being controllable independently. The apparatus also comprises a sensing device for detecting the phase line current operating conditions and a control device for controlling each pair of switches based on the current operating conditions.

Description

SWITCHING APPARATUS AND METHOD FOR VARYING THE IMPEDANCE OF A PHASE LINE OF A SECTION OF AN ELECTRIC POWER TRANSMISSION LINE

The present invention relates to an apparatus and a switching method for varying the impedance of a phase line of a section of an electric power transmission line. In the present text, we will call "phase line" which is commonly called by those skilled in the art 0 "phase". The apparatus and the method can be used inter alia but not exclusively to defrost an electric power transmission line, to modify the flow of power through an electric power transport line statically or dynamically, to stabilize a 5 network of electric power transmission lines, filtering harmonics of an electric power transport line, absorbing or dissipating energy transported by an electric power transport line, or even limiting the current d 'an electric power transmission line 0.

Known in the prior art, there is the American patent no 2,797,344 issued on June 25, 1957, and naming as inventor Sir WT Peirce. This patent describes an apparatus for de-icing electric cables. This patent. 5 proposes that in an electrical power transmission line, a cable is made by a pair of conductors insulated from each other. An electric bridge is provided in series with one of said conductors. Means are provided for opening the electric bridge, and other means are provided for controlling the operation of the electric bridge in response to an accumulation of ice on the cable. The bridge electrical includes a normally closed switch which is opened by means which responds to ice buildup on the cable.

Known in the prior art, there is also the American patent no 4,082,962 issued on April 4, 1978, and naming as inventors Vladimir Vladimirovich BURGSDORF et al. This patent describes a device for melting ice using direct current in the conductors of a suspended power transmission line. This patent proposes to use a rectifier which is connected momentarily to the end of one of the conductors of the line. The device also includes a grounding circuit and a filtering circuit connected in parallel to the rectifier. The circuit proposed in this patent uses a rectified current to deglaze the line. For each line section, a rectifier, a grounding circuit and a filtering circuit are used.

Known in the prior art, there is also American patent No. 4,126,792 issued on November 21, 1978, and naming as inventors Georgy A. GENRIKH et al. This patent proposes a high voltage network for regions where frost is present in large quantities. This patent proposes the use of a rectifier and a switching circuit which make it possible to connect at least one conductor of the line to the rectifier in order to melt the frost by a rectified current.

Known in the art, there is also American patent No. 4,119,866 issued October 10, 1978, and naming as inventors Georgy Andreevich GENRIKH et al. This patent proposes the use of a direct current source and of various switches connected to a line section to deglaze a conductor of the line by direct current.

Known in the prior art, there is also American patent No. 4,190,137 issued on February 26, 1980, and naming Akira SHIMADA et al. As inventors. This patent describes an apparatus for deicing tramway cables. This patent proposes to form loops with different sections of the tram power cables and to use a certain type of transformers to pass in the loops in question a current which is superimposed on the supply current to thereby deglaze power cables.

Also known in the prior art, there are the following US patents which describe different line switching apparatus and methods for different applications: 2,240,772; 2,852,075; 4,028,614; 4,085,338; 4,135,221; 4,322,632; 4,489,270; 4,492,880; 4,769,587; 5,124,882; 5,483,030; 5,734,256; 5,777,837; and 5,754,045. So, one of the drawbacks is that. found in all the switching devices and methods mentioned above, lies in the fact that the strategies offered to the user to vary the impedance of a section of a power transmission line electric with multiple phase lines are limited.

One of the objectives of the present invention is to propose an apparatus and a switching method for varying the impedance of a section of an electric power transmission line with phase lines with multiple conductors according to a wide range of possibilities. larger than is possible in the prior art, of a effectively and safely.

The objects, advantages and other characteristics of the present invention will become more apparent on reading the following description, which is not intended to be restrictive, of the various preferred embodiments given by way of example only with reference to the attached drawings.

1 Summary of the Invention: The present invention is ^a. switching device for varying the impedance of a phase line of a section of an electric power transmission line, the phase line comprising n conductors electrically isolated from each other and short-circuited between them ends of the section, the apparatus comprising: for each of at least one of the n conductors, a passive component and a pair of electromechanical and electronic switches connected in parallel to each other, the pair of switches being suitable selectively connecting and disconnecting the passive component in series with the corresponding conductor in response to control signals, the switches of each pair being independently controllable; detection means for detecting current operating conditions of the phase line; and control means for controlling each pair of switches according to the current operating conditions detected by the detection means.

The present invention also relates to a switching device for varying the impedance of a phase line of a section of an electric power transmission line, the phase line comprising n conductors electrically isolated from each other and short-circuited between them at two ends of the section, the apparatus comprising: for each of at most n-1 of the n conductors, an electronic switch capable of opening or selectively closing the corresponding conductor in response to control signals; detection means for detecting current operating conditions of the phase line; and control means for controlling the electronic switch according to the current operating conditions detected by the detection means.

The present invention also relates to a switching method ¹ for varying the impedance of a phase line of a section of an electric power transmission line, the phase line comprising n conductors electrically isolated from each other and short-circuited together at two ends of the section, the method comprising the following steps: (a) detecting current operating conditions of the phase line; and

(b) order pairs of switches, electromechanical and electronic connected in parallel to each other according to the current operating conditions detected in step (a) to selectively connect and disconnect at least one component passive connected respectively in series with at least one of the n conductors in response to control signals, the switches of each pair being independently controllable. The present invention also relates to a switching method for varying the impedance of a phase line. of a section of an electric power transmission line, the phase line comprising n conductors electrically isolated from each other and short-circuited between them at two ends of the section, the method comprising the following steps:

(a) detecting current operating conditions of the phase line; and

(b) controlling electronic switches according to the current operating conditions detected in step (a) to selectively open or close at most n-1 of the n conductors in response to control signals.

Brief description of the drawings:

Figure 1 is a schematic circuit diagram showing a phase line provided with a switch according to a preferred embodiment of the present invention.

Figure 2 is a schematic circuit diagram showing a phase line provided with switches according to a preferred embodiment of the present invention. Figure 3 is a schematic circuit diagram showing a three-phase line section provided with switches according to a preferred embodiment of the present invention.

Figure 4 is a circuit diagram showing a preferred embodiment of an element shown in Figures 1, 2 or 3, according to the present invention.

FIG. 5 is a block diagram of an apparatus according to a preferred embodiment of the present invention, in relation to FIG. 3. FIG. 6 is a schematic circuit diagram showing a section of a three-phase line provided switches according to a preferred embodiment of the present invention.

FIG. 7 is a block diagram of an apparatus according to a preferred embodiment of the present invention, in relation to FIG. 6.

Figure 8 is a partial and schematic side view of a preferred embodiment of an element shown in Figure 7, in a first position, according to the present invention. Figure 9 is a partial and schematic side view of the element shown in Figure 8 in a second operating position, according to the present invention.

FIG. 10 is a schematic circuit diagram showing a section of a three-phase line provided with switches according to a preferred embodiment of the present invention.

FIG. 11 is a schematic circuit diagram showing a three-phase line section provided with switches according to the preferred embodiment of the present invention.

Figure 12 is a schematic circuit diagram showing a three-phase line section provided with switches according to a preferred embodiment of the present invention. FIG. 13 is a schematic circuit diagram showing a three-phase line section provided with switches according to a preferred embodiment of the present invention.

Figure 14 is a schematic circuit diagram showing a three-phase line section provided with switches according to a preferred embodiment of the present invention.

Figure 15 is a block diagram of an apparatus according to a preferred embodiment of the present invention, in connection with Figures 12, 13 and 14. Figure 16 is a front view of a pylon supporting a transmission line electrical energy on which apparatuses according to a preferred embodiment of the present invention are mounted.

Figure 17 is a side view of the pylon shown in Figure 16.

FIG. 18 is a perspective view of an element shown in FIGS. 16 and 17.

Detailed description of the drawings: If we now refer to FIG. 1, we can see a phase line of a section 3 of an electric power transmission line which generally includes other phase lines (not shown). In the present case, the phase line shown comprises two conductors 13 and 15 electrically isolated from one another and short-circuited between them at two ends of the section 3 by short-circuits 2. An equivalent circuit of the self inductance 8, mutual inductance 17 and resistance 10 is indicated. For the purposes of discussion, the capacitive effects of the line are neglected. The apparatus comprises an electronic switch 59 which could also be a pair of electromechanical and electronic switches connected in parallel, and a passive component which in this case is a capacitor 11. The switch 59 and the capacitor 11 are connected in series with the conductor 13 of the phase line. The other driver 15 of the line phase is simply a short circuit. The simplified representation of a phase line shown in FIG. 1 makes it possible to understand that by opening and closing the switch 59 it is possible to vary the impedance of the section 3 of the line for transporting electrical energy. A person skilled in the art will also understand that the present configuration shows the elements of an RLC circuit (resistance, inductance and capacitor), and that the value of the capacitor 11 can be chosen as a function of the operating frequency to obtain 1 ' desired impedance.

The addition of the capacitor 11 in series with the conductor 13 makes it possible to increase the current in one of the two conductors 13 and 15 of the phase line to a value greater than the current of the phase line which is the sum of the currents flowing in the conductors 13 and 15 of the phase line, so as, for example, to promote de-icing. Thus, de-icing of a conductor of a phase line is possible even when the current in the phase line is less than the required de-icing current. It is possible to pass the required de-icing current through the conductor even if the current of the phase line would have a value situated for example between the de-icing current and half of it. The line inductance is the element of an RLC circuit. The addition of a capacitor in series with the conductor 13 also makes it possible to change the impedance of the line, that is to say to increase or decrease the impedance of the line according to the value of the capacitor. This allows the power flow in the line to be controlled. This change in impedance allows power to be transferred from one line to another. Adding one or more devices according to the present invention on several sections of a phase line allows to increase the desired effect on the power transmission line. With an appropriate distribution of devices according to the present invention in a transport network and real-time control of the impedance of the phase lines, the stability of the network and consequently the capacity of line transit can be increased.

An apparatus according to the present invention provided with a capacitor makes it possible to make FACTS "flexible alternative current transmission Systems" by using the own inductance and the mutual inductance of the conductors of the phase line as an element of an RLC circuit. This embodiment and those which will be described in the present application make it possible to carry out FACTS without reference to the mass and without requiring physical space in a transformer station, which represents an important economic advantage. The appropriate switching sequence of the device switches achieves the desired effect. Using the line choke with a capacitor connected to the line helps reduce the costs of FACTS.

The apparatus according to the present invention provided with a capacitor also makes it possible to filter the harmonics on a direct current transmission line with phase lines with multiple conductors. By means of several devices according to the present invention, it is possible to act on several phases simultaneously. The device according to the present invention can be used to absorb or dissipate energy by adding dissipation resistors to the outside of the case of the device and inside the four conductors of a phase line on the side where the four conductors are interconnected. In addition, the present invention can be used as a current limiter. Referring now to FIG. 2, we can see a phase line of a section 3, comprising three conductors each provided with a switch 59 and a capacitor 11, and a fourth conductor 15 which is a short circuit. A person skilled in the art will understand that the circuit shown in FIG. 2 offers a greater range of possibilities for varying the impedance of the phase line in comparison with the circuit shown in FIG. 1 since this time three switches 59 can be operated. Referring now to Figure 3, we can see a section of an electric power transmission line provided with elements according to a preferred embodiment of the present invention to vary the impedance of the phase lines of the section. For example, the power transmission line is a three-phase 735 kV line.

The electric power transmission line comprises three phase lines 5, 7 and 9. Each of the phase lines 5, 7 and 9 comprises several conductors 13 electrically isolated from each other to conduct the phase current. The conductors 13 of each phase line are short-circuited between them at the two ends of the section 3 by short-circuits 2.

In the present case, three devices according to the present invention are respectively provided for the three phase lines 5, 7 and 9. For each conductor of a phase line 5, 7 or 9, the device comprises a component passive preferably in the present case a capacitor 11, and a pair of electromechanical and electronic switches 6 connected in parallel to each other. However, it is not essential that all the conductors 13 of a phase line are provided with a passive component and a pair of switches. The pair of switches 6 can be produced as shown in FIG. 4. Each pair of switches 6 is able to selectively connect and disconnect the corresponding capacitor 11 in series with the corresponding conductor 13 in response to signals from ordered . The switches of each pair 6 are independently controllable as we will see in connection with FIG. 4. In this FIG. 3, in order not to overload the figure, the numerical references 6, 11 and 21 have only been shown in relation to some of the corresponding elements that can be seen at the top of Figure 3. However, it should be understood that these numerical references designate all the similar elements that are found in the three phase lines 5, 7 and 9. Thus , for each phase line 5, 7 or 9, four capacitors 11 and four pairs of switches 6 are provided for the four conductors 13. Each pair of switches 6 is connected in series with the corresponding conductor 13. Each capacitor 11 is connected in parallel with the corresponding pair of switches 6. It can also be seen that each capacitor 11 is connected in series with a discharge resistor 21 which is of low value. Thus, each conductor 13 can be closed to form a short circuit by closing its pair of switches 6 or can be put in series with a corresponding capacitor by opening its pair of switches 6. As can be seen, the different operating modes mentioned above are possible on each of the conductors of each of the phase lines 5, 7 and 9. This therefore results in a large margin of maneuver for varying the impedance of the phase lines of section 3.

Conventional spark gaps 12 which can be semiconductor spark gaps such as avalanche diodes or varistors, are provided to protect the insulators of the spreaders and spacers during an overload of line current which can induce an overvoltage between the conductors of the same phase line.

The apparatus also includes a detection device for detecting the current operating conditions of the corresponding phase line. This detection device is preferably produced by the circuit shown in FIG. 5.

The apparatus also comprises a control device for controlling each pair of switches 6 of the same phase line as a function of the current operating conditions detected by the detection device. A preferred embodiment of this control device will be described in relation to FIG. 5. For safety reasons, the electromechanical switches of the pairs of switches of the same phase line 5, 7 or 9 are actuated by a mechanism common which does not allow all the electromechanical switches of the same phase line to be opened simultaneously so as never to open a phase line. According to the preferred mode of application, the present invention can be used to manage the flow of power in a section of an electric power transmission line by varying the impedance of the phase lines with the pairs of switches 6 For example, to change the power flow on a 735 kV transmission line mouth supplied by lines coming from distant dams, it is enough to modify the operating position of the pairs of switches of the switching devices associated with the phase lines to also modify the power flow. For this purpose, it is possible to permanently open electromechanical switches of pairs of predetermined switches associated with predetermined phase lines, and to use the electronic switches of said pairs of predetermined switches to open and close the corresponding conductors and thus control in time real power flow and stabilize the electrical network with a fine and active control. A change in impedance on different lines produces a different power flow. There are a very large number of possible combinations depending on the state in which the different pairs of switches are placed. The application described above is very useful for performing active stabilization of the network by dynamic control of the power flow.

Referring now to FIG. 4, we can see how the pairs of switches 6 are made. The pair of switches 6 comprises an electronic switch 23 in parallel with an electromechanical switch 19 to form a pair of switches electromechanical and electronic 6. According to a preferred embodiment, the electronic switch 23 is used to allow the transitions of the corresponding electromechanical switch and is slaved to the latter. However, according to another preferred embodiment, the electronic switch 23 can be used to take over from the electromechanical switch 19 if the latter, following a fault, remains in the open position for certain conductors of the phase line. The electronic switch 23 is provided with a damper 27 and a protection circuit not shown. The electronic switch 23 is used when one wants to switch the electromechanical switch so as to remove the voltage across the electromechanical switch during switching. When a closing signal is sent to the pair of switches 6, the electronic switch 23 closes before the electromechanical switch, and when an opening signal is sent, the electromechanical switch 19 opens before the switch electronic 23. The electronic switch 23 can for example be a thyristor, triac, GTO, MOSFET, IGBT, etc.

To carry out a control of the flow of power, the electronic switch 23 must be able to be controlled by a command coming from the outside through a control device. This control device makes it possible to change the power flow of the network in real time by dynamically changing the impedance of the lines, by controlling only the electronic switches 23 after having opened the electromechanical switches 19 on certain conductors. This order can be made at from a central unit which analyzes the flow of power and sends appropriate signals to the various control devices to open or close, under dynamic conditions, the various electronic switches. Referring now to FIG. 5, one can see a preferred embodiment of an apparatus according to the present invention which comprises inter alia a control device and a detection device for controlling the pairs of switches of one of the lines phase shown in FIG. 3. The apparatus comprises a processor 70 having an input port 74 for receiving signals indicative of the operating positions of the electromechanical switches, input ports 76 for receiving signals indicative of the voltages of terminal of the pairs of switches, an input port 73 for receiving signals indicative of the phase current in the phase line, an input port 75 for counting the turns of the mother screw 52, and outputs 77 or 79 to generate control signals. The unit also includes a radio frequency transmitter 66 connected to the processor 70 to transmit signals indicative of the operating positions of the switches, the voltages at the terminals of the pairs of switches, the numbers of revolutions made by the mother screw, and the current. phase in the phase line. A radio frequency receiver 64 is also provided. The receiver 64 and the transmitter 66 are respectively provided with antenna 68. The receiver 64 is connected to the processor 70 to receive radio frequency control signals from which the control signals are produced. The unit also includes an amplifier 72 connected to the processor 70 to control the motor 40 according to the control signals. The amplifier 72 and the motor 40 are connected to the control of the electromechanical part of the pairs of switches 6 shown in FIGS. 3 and.

An electrical supply device is provided for supplying the processor 70, the receiver 64, the transmitter 66 and the amplifier 72. This electrical supply device comprises a first electrical supply source 78 comprising a battery 82 and a sensor solar 80 connected to the battery 82. This power supply device also comprises a second power supply source 81 connected in parallel to the first power supply source 78, and having inputs 83 connected to the conductors of the power line. phase. Thus, when one of the conductors is open, the supply can be made from this conductor by means of the supply 81 via one of the inputs 83.

The input port 75 is connected to a tachometer of the mother screw 52 to know its position. The port 74 is used to receive a signal representative of the position of a carriage which is moved by the mother screw 52. Each carriage groups together all of the electromechanical switches of the pairs of switches of the phase line. The position of the carriage is representative of the position of each of the electromechanical switches associated therewith. The receiver 64 and the transmitter 66 respectively make it possible to receive and transmit radio frequency signals. The pairs of switches are actuated according to the radio frequency signals received. The radio frequency signals emitted by the transmitter 66 make it possible to confirm the reception of the radio frequency control signals and possibly to confirm their execution. The receiver 64 is permanently capable of receiving the remote radio frequency signals which are coded.

Referring now to FIG. 6, we can see a circuit similar to that shown in FIG. 3 except that it additionally comprises pairs of electromechanical and electronic switches 25. It is therefore possible to completely open a conductor 13 by opening the corresponding pairs of switches 6 and 25. For each conductor 13, a new possibility of variation of impedance is therefore offered. These pairs of switches 25 can be produced in a similar manner to that shown in FIG. 4 but they could also be replaced by electronic switches. The switches of a pair of switches 25 are independently controlled as will be explained in relation to FIG. 7.

Referring now to FIG. 7, one can see a preferred embodiment of an apparatus according to the present invention which comprises a detection device, a control device and the pairs of switches shown in FIG. 6.

The apparatus comprises a processor 70 having an input port 74 for receiving signals indicative of the operating positions of the electromechanical switches of the pairs of switches 6, input ports 76 for receiving signals indicative of the terminal voltages of the pairs of switches 6, an input port 73 for receiving signals indicative of the phase current in the phase line, an input port 75 for counting the turns of the mother screws 52, and outputs 63, 65, 77 and 79 to generate control signals. The input port 75 is connected to the tachometer counters 52 to know their position. The port 74 is used to receive a signal representative of the position of the carriage moved by the mother screw 52 of the pairs of switches 6. The carriage groups together all of the electromechanical switches of the pairs of switches 6 of the phase line. The position of the carriage is therefore representative of the position of each of the electromechanical switches associated therewith. The transmitter 66 which operates intermittently or continuously confirms the command received, the execution time of the command, the state of the batteries and the voltage in the conductors. The information relating to the voltage at the terminals of the open conductor makes it possible at the same time to determine the current which passes through the other conductors which are closed. A receiver and a zone transmitter which are not illustrated are also provided for receiving data from a load cell (not shown) mounted on the phase line and retransmitting the data received from the remote load cell to a station. central control (not shown).

Referring now to Figures 8 and 9, a preferred embodiment of the electromechanical part of the pairs of switches 25 shown in Figures 6 and 7 can be seen - in open and closed positions, respectively. It is an electromechanical switch which includes two terminals 29 and 31, and a cradle 56 capable of moving along the mother screw 52. This cradle 56 comprises a contact of movable conductors 26 having a conductive surface capable of entering in contact with the conductive cursor 24. A motor device is provided for moving the cradle 56 by actuating the mother screw 52. This motor device is controlled by the control device shown in FIG. 7. This motor device comprises a motor 40, and a speed reducer 50 coupled to the motor. 40. The lead screw 52 has one end connected to the speed reducer 50, and another end 54 connected to an anchor point in the housing (not shown). Flexible cables 39 connect the movable conductive contact 26 to the terminal 31. If the ¹ Referring now to the circuit shown in Figure 10, there is shown a circuit similar to that shown in Figure 6 but in this case , each of the capacitors is a variable capacitor 27 and controllable by the device control device. Thus, the apparatus according to the present invention as shown in Figure 10 allows even more possibilities for variations of the impedance of a phase line.

Referring now to FIGS. 11, 16 and 18, we can see, according to a preferred embodiment of the present invention, the housings 92 of the devices designed to each contain the pairs of switches of a phase line , a detection device and a control device. As can be seen more specifically in FIG. 11, for each phase line, four passive components 11 and 61 and four pairs of switches 6 are provided. Each pair of switches 6 is connected in series with the corresponding conductor. Each passive component 61 or 11 is connected in parallel with the corresponding pair of switches 6. The passive components provided on three of the four conductors are capacitors 11, while the passive component provided on the fourth conductor is a power resistor 61. The power resistor 61 has a terminal connected to one end of the section where the conductors are short-circuited, and it is physically located inside the volume delimited by the four conductors of the phase line, and outside the corresponding housing 92. This embodiment allows switching with damper.

Referring now to Figure 12, we can see another preferred embodiment according to the present invention. According to this embodiment, each device comprises for each of at most three of the four conductors of a phase line, an electronic switch 59 capable of selectively opening and closing the corresponding conductor in response to control signals. Each device also comprises a detection device and a control device which will be described in more detail with reference to FIG. 15. In addition, each device comprises a housing 92 for containing electronic switches 59, a detection device and a device. control. According to this embodiment, for each phase line, three electronic switches 59 are provided for three of the four conductors of a phase line. For each of the three conductors, the electronic switch is connected in series with the corresponding conductor, and a power resistor 61 is connected in parallel with the corresponding electronic switch 59. Each power resistor 61 has a terminal connected at one end 2 of the section where the conductors are short-circuited. Each power resistor 61 is physically located inside the volume delimited by the four conductors of the corresponding phase line and outside the housing 92. This device produces a damping circuit.

Referring now to Figure 13, we can see a configuration which achieves a current limiting circuit. This configuration is similar to that shown in FIG. 12, however there is no power resistor connected in parallel with the electronic switches 59. A person skilled in the art will easily understand when by actuating the switches 59 one can limit the current flowing through each phase line.

Referring now to Figure 14, we can see a configuration which achieves a current limiting circuit with capacitor. This configuration is similar to that shown in FIG. 12, however capacitors 11 replace the power resistors. A person skilled in the art will readily understand that by actuating the switches 59 one can limit the current through each of the phase lines. Referring now to FIG. 15, one can see a preferred embodiment of an apparatus according to the present invention for controlling the electronic switches 59 shown in FIGS. 12, 13 and 14. The apparatus comprises three electronic switches 59, a detection device and a control device.

The processor 70 has input ports 76 for receiving signals indicative of the voltages at the terminals of the electronic switches, and an input port 75 for receiving signals indicative of the phase current in the phase line. The detection device comprises a radio frequency transmitter 66 connected to the processor 70 for send signals indicative of the voltages at the terminals of the electronic switches 59 and of the phase current, and a power supply source 78 to supply the processor 70 and the transmitter 66. The controller includes the processor 70 which further includes outputs 65 for transmitting the control signals to control the electronic switches 59. The controller also includes a radio frequency receiver 64 connected to the processor 70 for receiving radio frequency signals from control from which control signals are produced, and the power source 78 to further power the receiver 64. The power source 78 includes a battery 82 and a solar collector 80 connected to the battery 82. In Referring now to FIG. 16, one can see a front view of a pylon provided with apparatuses of which the housings 92 can be seen, according to the present invention. The boxes 92 are supported by supports 90. Each box 92 contains one of the devices shown in FIGS. 5, 7 and 15.

Referring now to FIG. 17, one can see a side view of the pylon shown in FIG. 16. In this FIG. 17, it can be seen that the housings 92 do not have to withstand the mechanical tension which is present in the transmission line 94. In addition, we can see four load cells 91 which are mounted on the four phase lines.

Referring now to FIG. 18, one can see a perspective view of one of the housings 92 shown in FIGS. 16 and 17. More particularly, the housing shown in FIG. 18 contains the apparatus shown in FIG. can see the switching terminals 18 of the device, as well as crossbar insulators 28. We can also see openings 37 as well as an indicator ball 39 which is used to indicate the position of the electromechanical switches of the pairs of switches 6 to a technician on site.

Claims

CLAIMS:

1. A switching device for varying the impedance of a phase line of a section of an electric power transmission line, the phase line comprising n conductors electrically isolated from each other and short-circuited between them at two ends of the section, the apparatus comprising: for each of at least one of the n conductors, a passive component and a pair of electromechanical and electronic switches connected in parallel to each other are provided, the pair switches adapted to selectively connect and disconnect the passive component in series with the corresponding conductor in response to control signals, the switches of each pair being independently controllable; detection means for detecting current operating conditions of the phase line; and control means for controlling each pair of switches according to the current operating conditions detected by the detection means.

2. Apparatus according to claim 1, wherein each of the passive components is a capacitor.

3. Apparatus according to claim 2, in which: for at most n-1 conductors, n-1 capacitors and n-1 pairs of switches are provided; the n-1 pairs of switches are respectively connected in series with the n-1 conductors; and the n-1 capacitors are respectively connected in series with the n-1 pairs of switches.

4. Apparatus according to claim 2, in which: n capacitors and n pairs of switches are provided for the n conductors; the n pairs of switches are respectively connected in series with the n conductors; and the n capacitors are respectively connected in parallel with the n pairs of switches.

5. Apparatus according to claim 1, comprising a housing for containing the pairs of switches, the detection means and the control means, and in which: n passive components and n pairs of switches are provided for the n conductors; the n pairs of switches are respectively connected in series with the n conductors; the n passive components are respectively connected in parallel with the n pairs of switches; a switch is connected in series with each of the passive components; the passive components provided for n-1 of the n conductors are capacitors; and the passive component provided for the nth conductor is a power resistor, the power resistor having a terminal connected to one end of the section where the conductors are short-circuited, the power resistor being physically located inside a volume delimited by the n conductors and outside the housing.

6. Apparatus according to claim 1, in which: for at most n-1 of the n conductors, n-1 passive components and n-1 pairs of switches are provided; the n-1 pairs of switches are respectively connected in series with the n-1 conductors; and the n-l passive components are respectively connected in parallel with the n-l pairs of switches.

7. Apparatus according to claim 6, wherein each of the passive components is a power resistor.

8. Apparatus according to claim 6, wherein each of the passive components is a capacitor.

9. Apparatus according to claim 4, wherein each capacitor is connected in series with a discharge resistor.

10. Apparatus according to claim 9, further comprising switches connected respectively in series with the capacitors, each of the switches being controllable by the control means.

11. Apparatus according to claim 10, wherein each of the switches comprises a pair of electromechanical and electronic switches connected in parallel and independently controllable by the control means.

12. Apparatus according to claim 10, wherein each of the capacitors is a variable capacitor and controllable by the control means.

13. Apparatus according to claim 5, wherein each of the switches comprises a pair of electromechanical and electronic switches connected in parallel and independently controllable by the control means.

14. An apparatus according to claim 1, in which: the detection means comprise: a processor having a first input port for receiving signals indicative of the operating positions of the pairs of switches, second input ports for receiving signals indicative of the voltages across the pairs of switches, and a third input port for receiving signals indicative of the phase current; a radiofrequency transmitter connected to the processor for transmitting signals indicative of the operating positions of the electromechanical switches of the pairs of switches, of the voltages at the terminals of the pairs of switches and of the phase current; and power supply means for supplying the processor and the transmitter; the control means comprise: the processor which further comprises outputs for transmitting the control signals for controlling all the pairs of electromechanical and electronic switches; a radio frequency receiver connected to the processor for receiving radio frequency control signals from which the control signals are produced; and the power supply means for further supplying the receiver and the amplifier.

15. A switching device for varying the impedance of a phase line of a section of an electric power transmission line, the phase line comprising n conductors electrically isolated from each other and short-circuited between them at two ends of the section, the apparatus comprising: for each of at most nl of the n conductors, an electronic switch capable of selectively opening or closing the corresponding conductor in response to control signals; detection means for detecting current operating conditions of the phase line; and control means for controlling the electronic switch as a function of the current operating conditions detected by the detection means.

16. Apparatus according to claim 15, comprising a housing for containing the electronic switches, the detection means and the control means, and in which: nl electronic switches are provided for the n-1 conductors; the nl electronic switches are respectively connected in series with the nl conductors; and a power resistor is connected in parallel with each of the nl electronic switches, the power resistor having a terminal connected at one end of the section where the conductors are short-circuited, the power resistor being physically located inside a volume delimited by the n conductors and outside the housing.

17. An apparatus according to claim 15, in which: the detection means comprise: a processor having first input ports for receiving signals indicative of the voltages at the terminals of electronic switches, and a second input port for receiving signals indicative of phase current; a radiofrequency transmitter connected to the processor for transmitting signals indicative of the voltages at the terminals of the electronic switches, and of the phase current; and power supply means for supplying the processor, and the transmitter; the control means include: the processor which further includes outputs for transmitting the control signals for controlling the electronic switches; a radio frequency receiver connected to the processor for receiving radio frequency control signals from which the control signals are produced; and the power supply means for further supplying the receiver.

18. A switching method for varying the impedance of a phase line of a section of an electric power transmission line, the phase line comprising n conductors electrically isolated from each other and short-circuited between them at two ends of the section, the method comprising the following steps:

(a) detecting current operating conditions of the phase line; and

(b) order pairs of electromechanical and electronic switches connected in parallel to one another according to the current operating conditions detected in step (a) to selectively connect and disconnect at least one passive component respectively connected in series with at least one of the n conductors in response to control signals, the switches of each pair being independently controllable.

19. A switching method for varying the impedance of a phase line of a section of an electric power transmission line, the phase line comprising n conductors electrically isolated from each other and short-circuited between them at two ends of the section, the method comprising the following steps:

(a) detecting current operating conditions of the phase line; and

(b) controlling electronic switches as a function of the current operating conditions detected in step (a) to selectively open or close at most n-l of the n conductors in response to control signals.