Three-phase overhead line ice-melting device and control method

Abstract

The application discloses a kind of three-phase overhead line ice-melting device and control method, belong to power transmission and distribution technical field, it is applied to the ice-melting section of overhead line including three-phase conductor, the device includes: the conductor of ice-melting section, conductor is configured as parallel first power transmission branch and second power transmission branch;Bus tie switch is set on second power transmission branch, for disconnecting to isolate second power transmission branch when conductor ice-melting;Switch group is used to electrically connect the high-voltage side terminal and low-voltage side terminal of autotransformer to the two ends of second power transmission branch respectively when bus tie switch is disconnected;Autotransformer is used to obtain electric energy from overhead line.The application realizes uninterrupted power operation by ice-melting in isolated partial branch, and another branch is kept continuously powered;And can be powered by autotransformer on line itself, get rid of the dependence on external power supply, reduce cost, applicable to precision ice-melting of local line.

Description

Technical Field

[0001] This invention belongs to the field of power transmission and distribution technology, specifically relating to a three-phase overhead line uninterrupted de-icing device and control method. Background Technology

[0002] During the transmission and distribution of power through overhead transmission lines, icing is prone to occur in cold weather conditions, which can lead to faults such as conductor breakage and tower collapse, threatening the safety of the power grid. To address this problem, DC de-icing technology is typically employed.

[0003] However, traditional DC de-icing solutions have significant drawbacks: First, they require a dedicated external AC power supply, which imposes stringent requirements on the power conditions of the installation site and makes them unsuitable for various applications; second, the de-icing process usually requires power outages and switching operations, affecting the continuity and reliability of power supply; third, DC de-icing devices are mostly customized products with long production cycles, making them difficult to meet the sudden emergency needs of extreme weather; and finally, their equipment costs and engineering implementation expenses are high.

[0004] Therefore, how to effectively solve the problem of severe icing in specific areas (such as short-distance lines in mountainous areas with micro-meteorological conditions) is an urgent issue to be addressed. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a three-phase overhead line uninterrupted de-icing device and control method to solve the problems of de-icing operations relying on external power supply, requiring power outage operation, high cost, and inability to accurately de-ic the local line.

[0006] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a three-phase overhead line uninterrupted de-icing device, applied to a section of an overhead line containing three-phase conductors to be de-iced. The device includes: conductors of the section to be de-iced, the conductors of the section to be de-iced being constructed as a first transmission branch and a second transmission branch connected in parallel; a bus tie switch, disposed on the second transmission branch, used to disconnect during conductor de-icing to isolate the second transmission branch; a switch group, used to electrically connect the high-voltage side terminal and the low-voltage side terminal of an autotransformer to the two ends of the second transmission branch respectively when the bus tie switch is disconnected; and an autotransformer, used to obtain electrical energy from the overhead line.

[0007] Furthermore, the aforementioned overhead line is a three-phase overhead line, and the uninterrupted de-icing device for the three-phase overhead line is installed for each of the three phases.

[0008] Furthermore, each corresponding autotransformer in the three phases together constitutes a three-phase autotransformer bank.

[0009] Furthermore, the aforementioned overhead line also includes a ground wire, and the three-phase overhead line uninterrupted de-icing device also includes a ground wire de-icing unit; the ground wire de-icing unit includes: an independent secondary winding connected to a ground wire de-icing switch, and the independent secondary winding is electrically isolated from the winding of the autotransformer.

[0010] Furthermore, the aforementioned grounding de-icing switch includes at least one of the following: an AC circuit breaker for switching the connection between the independent secondary winding and the ground wire; and an isolating switch for switching the connection between the independent secondary winding and the ground wire.

[0011] Furthermore, the aforementioned switch group includes a high-voltage side switch and a low-voltage side switch of the autotransformer, and the switch group also includes at least one of a disconnecting switch and a grounding switch.

[0012] Furthermore, the aforementioned three-phase overhead line uninterrupted de-icing device also includes a measurement unit and a controller; the measurement unit is used to collect line icing data; the controller is used to execute the opening and closing operations of the bus tie switch and switch group based on the line icing data.

[0013] Furthermore, the aforementioned second transmission branch is an auxiliary conductor that is physically separate from and parallel to the first transmission branch.

[0014] Secondly, the present invention also provides a three-phase overhead line uninterrupted de-icing control method, applied to the three-phase overhead line uninterrupted de-icing device as provided in the first aspect. The control method includes: when de-icing of conductors in the section to be de-iced is required, disconnecting the bus tie switch installed on the second transmission branch and closing the switch group, electrically connecting the high-voltage side terminal and the low-voltage side terminal of the autotransformer to the two ends of the second transmission branch respectively, generating a de-icing current in the second transmission branch, and maintaining the first transmission branch connected in parallel with the second transmission branch to continuously supply power downstream; after the conductor de-icing is completed, disconnecting the switch group and closing the bus tie switch to restore the parallel transmission state.

[0015] Furthermore, the above-mentioned three-phase overhead line uninterrupted de-icing control method also includes: using an independent secondary winding to provide de-icing current to the ground wire by controlling the ground wire de-icing switch.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In this invention, on the one hand, by employing an autotransformer to obtain electrical energy from the overhead line itself, a voltage difference is created across the two ends of the section to be melted, thereby driving the melting current. This eliminates the need for an external dedicated power supply, solving the melting problem in scenarios without an external power source and providing convenient power access. On the other hand, by constructing the conductors of the section to be melted as a first and second parallel transmission branch, only the second transmission branch is isolated for melting, while the first transmission branch continuously supplies power to downstream loads, ensuring continuous power supply during melting and improving the reliability of the power grid. Furthermore, this three-phase overhead line uninterrupted ice melting device can precisely melt ice in short-distance sections prone to icing, such as micro-meteorological zones, avoiding the need to modify the entire line, thus reducing modification costs and increasing modification flexibility. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is one of the structural schematic diagrams of a three-phase overhead line uninterrupted de-icing device provided by the present invention; Figure 2 This is the second schematic diagram of the structure of a three-phase overhead line uninterrupted de-icing device provided by the present invention; Figure 3 This is a flowchart of a three-phase overhead line uninterrupted de-icing control method provided by the present invention; Figure 4 This is a schematic diagram of the operation process of de-icing using a conductor and a ground wire provided by the present invention; Figure 5 This is a schematic diagram of the operation process for separate de-icing of the ground wire provided by the present invention; Figure 6 This is a schematic diagram of the line operation status provided by the present invention; Figure 7 This is a schematic diagram of the structure of an ice-melting device for an autotransformer provided by the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., used in this specification are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] The following detailed description, in conjunction with the accompanying drawings, of the three-phase overhead line uninterrupted de-icing device and control method provided by the present invention through specific embodiments and application scenarios, will be provided in detail.

[0022] The three-phase overhead line uninterrupted de-icing device and control method provided by this invention can be applied to scenarios of uninterrupted de-icing of overhead lines, especially in micro-meteorological mountain sections where the line length is short, the icing is severe, and there is no external power supply on site.

[0023] This invention provides a three-phase overhead line uninterrupted de-icing device. Figure 1 A schematic diagram of a three-phase overhead line uninterrupted de-icing device provided by the present invention is shown. This device can be applied to the de-icing section of an overhead line containing three-phase conductors. Figure 1 As shown, the three-phase overhead line uninterrupted de-icing device 100 provided by the present invention may include conductors of the section to be de-iced, bus tie switch LK, switch group THS and TLS, and autotransformer T.

[0024] The conductors in the section to be melted are constructed as a first and second transmission branch connected in parallel; the bus tie switch LK is located on the second transmission branch and is used to disconnect during ice melting to isolate the second transmission branch; the switch group THS and TLS are used to electrically connect the high-voltage side terminal and the low-voltage side terminal of the autotransformer T to the two ends of the second transmission branch respectively when the bus tie switch LK is disconnected; the autotransformer T is used to obtain power from the overhead line.

[0025] In some embodiments of the present invention, the second power transmission branch is an auxiliary conductor that is physically separate from and parallel to the first power transmission branch.

[0026] In some embodiments of the present invention, the first transmission branch and the second transmission branch may also be different sub-conductors of the same split conductor.

[0027] In some embodiments of the present invention, the above-mentioned overhead line can be a three-phase overhead line.

[0028] Understandably, by using the bus tie switch LK installed on the second transmission branch, the bus tie switch can be disconnected when de-icing is required, thereby isolating the second transmission branch from the main transmission circuit. Simultaneously, the first transmission branch maintains its normal transmission function, ensuring the continuity of power supply to downstream loads and achieving uninterrupted power supply operations.

[0029] In some embodiments of the present invention, after the bus tie switch LK is opened, the switch groups THS and TLS are closed, electrically connecting the high-voltage and low-voltage terminals of the autotransformer T to the two ends of the isolated second transmission branch. Thus, the autotransformer T can directly obtain electrical energy from the overhead line, using its transformer principle to generate a specific voltage difference across the second transmission branch. This voltage difference can then drive a sufficiently large de-icing current in the branch, using the thermal effect (Joule heating) of the current to heat the conductors and melt the ice.

[0030] In this way, ice melting can be completed directly using the power of the circuit itself without the need for an external power source, thus solving the problem of dependence on a dedicated power source.

[0031] In some embodiments of the present invention, combined with Figure 1 ,like Figure 2 As shown, the three-phase overhead line uninterrupted de-icing device 200 provided by the present invention can be configured for each of the three phases.

[0032] Understandably, configuring each phase of a three-phase overhead line identically allows each phase conductor to be constructed as a parallel first and second transmission branch, equipped with its own bus tie switch, switch group, and autotransformer. This ensures the balance of the three-phase system during the de-icing process and enables independent or synchronous de-icing operations based on the icing condition of each phase.

[0033] like Figure 2As shown, one end of the A-phase power transmission line to be melted is the high-voltage side HV_A, and the other end is the low-voltage side LV_A. The A-phase conductor L_A includes two branch lines: L_A_1 (the first transmission branch of A-phase) and L_A_2 (the second transmission branch of A-phase). The L_A_1 line is a direct connection between connection point 1 and connection point 2. The L_A_2 line consists of two sections: connection point 1 to connection point 3 and connection point 2 to connection point 4. The connection and disconnection of the two sections between connection point 3 and connection point 4 are controlled by the bus tie switch LK_A. At connection point 3 of LK_A, disconnector AS1 is connected in series. The parallel grounding switch AES1 and the parallel voltage measuring device APT1 are connected. The surge arrester AF1 is connected to the high-voltage side switch THS_A of the autotransformer. The other end of THS_A is connected in sequence to the current measuring device ACT1 and the high-voltage connection terminal 13 of the autotransformer T_A. The disconnecting switch AS2, the parallel grounding switch AES2, the parallel voltage measuring device APT2, and the surge arrester AF2 are connected in series at connection point 4 of one end of LK_A to the low-voltage side switch TLS_A of the autotransformer. The other end of TLS_A is connected in sequence to the current measuring device ACT2 and the low-voltage connection terminal 14 of the autotransformer T_A.

[0034] The B-phase power transmission line to be melted has one end as the high-voltage side HV_B and the other end as the low-voltage side LV_B. The B-phase conductor L_B includes two branch lines: L_B_1 (the first transmission branch of B-phase) and L_B_2 (the second transmission branch of B-phase). The L_B_1 line is the direct connection between connection point 5 and connection point 6. The L_B_2 line consists of two sections: connection point 5 to connection point 7 and connection point 6 to connection point 8. The connection and disconnection of the two sections between connection point 7 and connection point 8 are controlled by the bus tie switch LK_B. At connection point 7 of LK_B, the disconnecting switch BS1 is connected in series. The parallel grounding switch BES1, the parallel voltage measuring device BPT1, and the surge arrester BF1 are connected to the high-voltage side switch THS_B of the autotransformer. The other end of THS_B is connected in sequence to the current measuring device BCT1 and the high-voltage connection terminal 15 of the autotransformer T_B. One end of LK_B, at connection point 8, is connected in series with the disconnecting switch BS2, the parallel grounding switch BES2, the parallel voltage measuring device BPT2, and the surge arrester BF2 to the low-voltage side switch TLS_B of the autotransformer. The other end of TLS_B is connected in sequence to the current measuring device BCT2 and the low-voltage connection terminal 16 of the autotransformer T_B.

[0035] The C-phase power transmission line to be melted has one end on the high-voltage side (HV_C) and the other end on the low-voltage side (LV_C). The C-phase conductor L_C includes two branch lines: L_C_1 (the first transmission branch of C-phase) and L_C_2 (the second transmission branch of C-phase). The L_C_1 line is a direct connection between connection point 9 and connection point 10. The L_C_2 line consists of two sections: connection point 9 to connection point 11 and connection point 10 to connection point 12. The connection and disconnection of the two sections between connection points 11 and 12 are controlled by the bus tie switch LK_C. At connection point 11 of LK_C, a disconnecting switch C is connected in series. S1, parallel grounding switch CES1, parallel voltage measurement CPT1, surge arrester CF1 are connected to the high-voltage side switch THS_C of the autotransformer. The other end of THS_C is connected in sequence to the current measurement device CCT1 and the high-voltage connection terminal 17 of the autotransformer T_C. One end of LK_C, at connection point 12, is connected in series with disconnecting switch CS2, parallel grounding switch CES2, parallel voltage measurement CPT2, surge arrester CF2 to the low-voltage side switch TLS_C ​​of the autotransformer. The other end of TLS_C ​​is connected in sequence to the current measurement device CCT2 and the low-voltage connection terminal 18 of the autotransformer T_C.

[0036] The neutral points of the three-phase autotransformers T_A, T_B, and T_C are grounded through connection point 19 and connected in series with the ground current measuring CT4.

[0037] In some embodiments of the present invention, the primary voltage of autotransformers T_A, T_B, and T_C is U1, and the secondary voltage is U2. The secondary side of the autotransformers is equipped with on-load or off-load taps to control the low-voltage output voltage U2. It can be understood that the de-icing capacity is the product of the current and voltage difference (U1-U2) of the non-common winding of the autotransformer, plus a coefficient of 1.732.

[0038] In some embodiments of the present invention, the switch group includes a high-voltage side switch and a low-voltage side switch of the autotransformer, and the switch group also includes at least one of a disconnecting switch and a grounding switch.

[0039] Understandably, disconnect switches are used to isolate voltage after a circuit breaker is tripped, creating a visible break point; while grounding switches are used to ground equipment before maintenance, releasing residual charge and ensuring personnel safety.

[0040] In some embodiments of the present invention, the autotransformers T_A, T_B, and T_C described above can be a single transformer or can constitute a three-phase autotransformer.

[0041] In some embodiments of the present invention, a three-phase autotransformer group can be formed by each corresponding autotransformer in the three phases.

[0042] For example, three single-phase autotransformers can share a core and casing to form a three-phase integrated autotransformer.

[0043] In some embodiments of the present invention, the bus tie switches LK_A, LK_B, and LK_C can be single switches or three-phase switches.

[0044] In some embodiments of the present invention, the above-mentioned autotransformer high-voltage side switches THS_A, THS_B, and THS_C can be a single switch or can be configured as a three-phase switch.

[0045] In some embodiments of the present invention, the aforementioned autotransformer low-voltage side switches TLS_A, TLS_B, and TLS_C ​​can be a single switch or can be configured as a three-phase switch.

[0046] In some embodiments of the present invention, the aforementioned disconnecting switches AS1, BS1, CS1, AS2, BS2, and CS2 can be single switches or three-phase switches.

[0047] In some embodiments of the present invention, the above-mentioned grounding switches AES1, BES1, CES1, AES2, BES2 and CES2 can be a single switch or a three-phase switch.

[0048] This simplifies the equipment structure, reduces the floor space required, and makes manufacturing and control more economical.

[0049] In some embodiments of the present invention, the above-mentioned overhead line may further include a ground wire, and the three-phase overhead line uninterrupted de-icing device provided by the present invention may further include a ground wire de-icing unit.

[0050] In some embodiments of the present invention, the ground wire de-icing unit may include: an independent secondary winding.

[0051] In some embodiments of the present invention, the independent secondary winding can be connected to a grounding de-icing switch, and the independent secondary winding is electrically isolated from the winding of the autotransformer. The grounding de-icing switch (not shown as a whole in the figure) can be composed of components such as an AC circuit breaker switch TS and a disconnecting switch S3.

[0052] It is understandable that the secondary winding is electrically isolated from the main winding (i.e., the common winding and the series winding) of the autotransformer, but can be coupled to the main winding on the same core.

[0053] In some embodiments of the present invention, the independent secondary winding can be connected to the ground wire segment that needs to be de-iced through a ground wire de-icing switch, thereby providing an independent and safe de-icing power supply for the ground wire to melt the ice covering the ground wire. At the same time, due to electrical isolation, the ground wire de-icing process will not cause electrical interference to the operation of the three-phase conductors of the main grid.

[0054] In some embodiments of the present invention, such as Figure 2 As shown, the autotransformer T_A has a separate secondary winding, forming a single-phase double-winding transformer. Its secondary winding T_D (i.e., the independent secondary winding) is connected in sequence to the measuring device CT3, the voltage measuring device PT3, the surge arrester F3, the AC circuit breaker TS, the parallel grounding switch ES3, and the disconnecting switch S3 (connected to grounding connection points 20 and 21 respectively). The grounding tie switch DK is connected between the grounding wires of the two overhead lines.

[0055] In some embodiments of the present invention, the above-mentioned grounding de-icing switch may include at least one of the following: an AC circuit breaker for switching the connection between the independent secondary winding and the ground wire; and an isolating switch for switching the connection between the independent secondary winding and the ground wire.

[0056] In some embodiments of the invention, the AC circuit breaker reliably interrupts the de-icing current, while the disconnecting switch provides a clear disconnect point during maintenance or non-de-icing conditions, thereby ensuring operational safety. It is understood that using both in combination can further improve the reliability and safety of the grounding de-icing circuit operation.

[0057] In some embodiments of the present invention, the three-phase overhead line uninterrupted de-icing device provided by the present invention may further include a measuring unit and a controller.

[0058] In some embodiments of the present invention, the above-mentioned measuring unit can be used to collect line icing data in real time.

[0059] In some embodiments of the present invention, the measuring unit may include, but is not limited to, an icing sensor, a current transformer, and a voltage transformer.

[0060] In some embodiments of the present invention, the above-mentioned line icing data may include the thickness and weight of the icing and the corresponding electrical parameters.

[0061] In some embodiments of the present invention, the controller described above can be used to perform the opening and closing operations of the bus tie switch and switch group based on line icing data.

[0062] In some embodiments of the present invention, the controller automatically executes the opening and closing operations of the bus tie switch and switch group based on the data collected by the measurement unit, according to the preset ice melting start threshold and control logic.

[0063] In some embodiments of the present invention, the de-icing operation modes corresponding to the three-phase overhead line uninterrupted de-icing device provided by the present invention may include conductor online de-icing mode, ground wire online de-icing mode, and normal operation mode.

[0064] In some embodiments of the present invention, such as Figure 1 As shown, when the three-phase line is operating normally and does not require de-icing, i.e., in normal operating mode, the bus tie switch LK is in the closed position, the high-voltage side switch THS of the autotransformer T is in the open position, the outgoing switch S1 is in the open position, and the grounding switch ES1 is in the closed position; the low-voltage side switch TLS of the autotransformer T is in the open position, the outgoing switch S2 is in the open position, and the grounding switch ES2 is in the closed position; the AC circuit breaker switch TS is in the open position, the outgoing switch S3 is in the open position, the grounding switch ES3 is in the closed position, and the ground wire tie switch DK is in the open position.

[0065] It is understandable that the outgoing switch S1 may contain multiple disconnect switches.

[0066] In some embodiments of the present invention, such as Figure 1 As shown, when the three-phase conductor line needs to be de-iced due to icing, i.e. in the online de-icing mode, the bus tie switch LK is in the open position, the high-voltage side switch THS of the autotransformer T is in the closed position, the outgoing switch S1 is in the closed position, and the grounding switch ES1 is in the open position; the low-voltage side switch TLS of the autotransformer T is in the closed position, the outgoing switch S2 is in the closed position, and the grounding switch ES2 is in the open position; the AC circuit breaker switch TS is in the open position, the outgoing switch S3 is in the open position, the grounding switch ES3 is in the closed position, and the ground wire tie switch DK is in the open position.

[0067] In some embodiments of the present invention, such as Figure 1 As shown, when the three-phase ground wire line needs to be de-iced due to icing, i.e. in the ground wire online de-icing mode, the bus tie switch LK is in the closed position, the high-voltage side switch THS of the autotransformer T is in the closed position, the outgoing switch S1 is in the closed position, and the grounding switch ES1 is in the open position; the low-voltage side switch TLS of the autotransformer T is in the open position, the outgoing switch S2 is in the open position, and the grounding switch ES2 is in the closed position; the AC circuit breaker switch TS is in the closed position, the outgoing switch S3 is in the closed position, the grounding switch ES3 is in the open position, and the ground wire tie switch DK is in the closed position.

[0068] In this way, by introducing automated control, it is possible to achieve accurate monitoring and timely response to icing, reduce manual intervention, improve the efficiency of de-icing operations, and enhance the intelligence level of power grid operation.

[0069] The three-phase overhead line uninterrupted de-icing device provided by this invention achieves uninterrupted operation by maintaining continuous power supply to another branch while de-icing a portion of the branch is isolated; furthermore, it can draw power from the line itself through an autotransformer, eliminating dependence on external power sources, reducing costs, and is suitable for precise de-icing of localized lines.

[0070] This invention also provides a method for controlling de-icing of three-phase overhead lines without power interruption, which can be implemented using the aforementioned three-phase overhead line de-icing device without power interruption. For example... Figure 3As shown, the three-phase overhead line uninterrupted de-icing control method may include the following steps 301 and 302.

[0071] Step 301: When de-icing is required on the conductors in the section to be de-iced, disconnect the bus tie switch on the second transmission branch and close the switch group. Electrically connect the high-voltage side terminal and the low-voltage side terminal of the autotransformer to the two ends of the second transmission branch respectively. De-icing current is generated in the second transmission branch, and the first transmission branch connected in parallel with the second transmission branch continues to supply power downstream.

[0072] Among them, the conductors in the aforementioned ice-melting section are constructed as a first and second transmission branch connected in parallel.

[0073] Step 302: After the conductor is de-iced, disconnect the switch group and close the bus tie switch to restore the parallel power transmission state.

[0074] In some embodiments of the present invention, when conductor de-icing is detected, the bus tie switch is first disconnected to isolate the second transmission branch from the main circuit; then the switch group is closed to connect the autotransformer to the second transmission branch, thereby generating de-icing current in that branch. It is understood that during this process, the first transmission branch remains connected to the downstream load, continuously supplying power. Then, after the conductor de-icing is complete, the reverse operation can be performed: first, the switch group is disconnected to cut off the de-icing power supply, then the bus tie switch is closed to reconnect the second transmission branch to the main circuit, restoring the parallel transmission state of the line. This process ensures uninterrupted power supply throughout the entire de-icing operation.

[0075] In some embodiments of the present invention, the above process can be controlled by a centralized controller or a control backend, or it can be controlled by local devices. The embodiments of the present invention do not specifically limit this.

[0076] In some embodiments of the present invention, a start-up threshold can be set for the three-phase overhead line uninterrupted de-icing device and control method provided by the present invention. The start-up threshold can be when the ice thickness of the line is greater than or equal to a preset thickness value, and the operating current of the three-phase line under low load cannot meet the current required for line de-icing.

[0077] The three-phase overhead line uninterrupted de-icing control method provided by this invention achieves uninterrupted operation by maintaining continuous power supply to another branch while de-icing a portion of the branch is isolated; furthermore, it can draw power from the line itself through an autotransformer, eliminating dependence on external power sources, reducing costs, and is suitable for precise de-icing of localized lines.

[0078] In some embodiments of the present invention, when the above-mentioned three-phase overhead line uninterrupted de-icing device includes a ground wire de-icing unit, and the ground wire de-icing unit includes an independent secondary winding, the three-phase overhead line uninterrupted de-icing control method provided by the present invention may further include the following step 303.

[0079] Step 303: By controlling the ground wire de-icing switch, the independent secondary winding is used to provide de-icing current to the ground wire.

[0080] In some embodiments of the present invention, step 303 can be performed independently of the wire de-icing process, or it can be performed after the wire de-icing process is completed.

[0081] Understandably, when there is ice on the conductors, the ice on the conductors needs to be melted first. After the ice on the conductors is melted, it is then decided whether to melt the ice on the ground wire based on the ice situation. However, when there is no ice on the conductors and only the ground wire is iced, the ground wire can be melted separately.

[0082] Specifically, with Figure 1 Taking the three-phase overhead line uninterrupted de-icing device shown as an example, as Figure 4 As shown, the operation of de-icing the conductor and ground wire together may include the following steps 401 to 429.

[0083] Step 401: While the line is in operation, monitor the icing status and operating current in real time, and continuously determine the icing status of the conductors and ground wires to determine whether de-icing operations are necessary.

[0084] Step 402: If it is determined that the conductor needs to be de-iced, start the de-icing process and disconnect the bus tie switch LK.

[0085] Step 403: Disconnect grounding switches ES1 and ES2.

[0086] Step 404: Close the outgoing line switch S1.

[0087] Step 405: Close the high-voltage side switch THS of the autotransformer.

[0088] Step 406: Close the outgoing line switch S2.

[0089] Step 407: Close the low-voltage side switch TLS of the autotransformer.

[0090] Step 408: The line forms an ice-melting circuit, generating ice-melting current, and the conductor ice-melting officially begins. The entire process is monitored online to track the line's operating status and ice-melting effect.

[0091] Step 409: Determine in real time whether the ice melting of the conductor is complete.

[0092] It is understandable that all current switch positions can be maintained until the wire de-icing is completed, and wire de-icing can continue while real-time monitoring is performed.

[0093] Step 410: Once the ice on the conductor has been removed, complete the conductor de-icing operation.

[0094] Step 411: Trip the low-voltage side switch TLS of the autotransformer.

[0095] Step 412: Disconnect the outgoing switch S2.

[0096] Step 413: Close the grounding switch ES2.

[0097] Step 414: Determine whether the ground wire needs to be de-iced.

[0098] If the ground wire does not require de-icing, you can skip directly to step 424 below to perform the line restoration operation.

[0099] Step 415: If the ground wire needs to be de-iced, close the ground wire interconnection switch DK.

[0100] Step 416, trip the grounding switch ES3.

[0101] Step 417: Close the outgoing switch S3.

[0102] Step 418: Close the AC circuit breaker switch TS.

[0103] Step 419: Apply de-icing current to the ground wire to carry out de-icing, and continuously monitor the line status online throughout the process.

[0104] Step 420: Ground wire de-icing complete.

[0105] Step 421: Open the AC circuit breaker switch TS.

[0106] Step 422: Disconnect the outgoing line switch S3.

[0107] Step 423: Close the grounding switch ES3.

[0108] Step 424: Open the ground wire connecting switch DK.

[0109] Step 425: Open the high-voltage side switch THS of the autotransformer.

[0110] Step 426: Disconnect the outgoing line switch S1.

[0111] Step 427: Close the grounding switch ES1.

[0112] Step 428: Close the bus tie switch LK.

[0113] Step 429: The line returns to normal operation, and the de-icing process is complete.

[0114] by Figure 1 Taking the three-phase overhead line uninterrupted de-icing device shown as an example, as Figure 5 As shown, the operation of de-icing the ground wire separately may include steps 501 to 518 as described below.

[0115] Step 501: While the line is in operation, monitor the icing status and operating current in real time, and continuously determine the icing status of the conductors and ground wires to determine whether de-icing operations are necessary.

[0116] Step 502: If the ground wire needs to be de-iced, close the ground wire interconnection switch DK.

[0117] Step 503: Disconnect the grounding switch ES1.

[0118] Step 504: Close the outgoing line switch S1.

[0119] Step 505: Close the high-voltage side switch THS of the autotransformer.

[0120] Step 506: Disconnect the grounding switch ES3.

[0121] Step 507: Close the outgoing line switch S3.

[0122] Step 508: Close the AC circuit breaker switch TS.

[0123] Step 509: The ground wire forms an independent de-icing circuit, and the ground wire de-icing is officially carried out. The line status and de-icing effect are monitored online throughout the process.

[0124] Step 510: Determine in real time whether the ground wire de-icing is complete and whether the normal operating conditions are met.

[0125] Step 511: When the ice melting is complete, open the AC circuit breaker TS.

[0126] Step 512: Disconnect the outgoing line switch S3.

[0127] Step 513: Close the grounding switch ES3.

[0128] Step 514: Open the ground wire connecting disconnect switch DK.

[0129] Step 515: Open the high-voltage side switch THS of the autotransformer.

[0130] Step 516: Disconnect the outgoing line switch S1.

[0131] Step 517: Close the grounding switch ES1.

[0132] Step 518: The line returns to normal operation, and the de-icing process is complete.

[0133] It should be noted that during the execution of steps 501 to 518 above, the bus tie switch LK is in the closed position.

[0134] This provides a flexible de-icing strategy to cope with different line icing conditions.

[0135] It should be noted that for other descriptions of steps 301 to 303 above, please refer to the detailed description of the three-phase overhead line uninterrupted de-icing device above. To avoid repetition, it will not be repeated here.

[0136] The following specific embodiments illustrate the uninterrupted power-on de-icing device and control method for three-phase overhead lines provided by the present invention.

[0137] Take the online de-icing under load of a 110kV three-phase overhead line as an example.

[0138] Assuming the required 1-hour de-icing current I1 for the line is 1000A, and the total de-icing resistance R for a three-phase line is 6Ω, then the voltage required for single-phase de-icing is 6kV, and the corresponding three-phase line voltage U required for de-icing is... ice The de-icing voltage is 10.4kV, U. ice =U1-U2.

[0139] Where U1 is the primary voltage of autotransformer T and U2 is the secondary voltage of autotransformer T.

[0140] The primary voltage U1 of the autotransformer T is 110kV, the secondary voltage U2 of the autotransformer T is 110kV-10.4kV=99.6kV, the transformation ratio of the autotransformer T is 110kV / 99.6kV, and the total capacity required for de-icing is 18MW.

[0141] When the three-phase line is operating normally, the bus tie switch LK is in the closed state, and the bus voltage is 110kV. At this time, the line operation status is as follows: Figure 6 As shown.

[0142] Assuming the equivalent load on the LV side of the line is 448.5Ω, the line current IS1 = 110kV / 1.732 / (448.5+1.5) = 141A, then I1 = 70.5A. At this current of 70.5A, in extreme weather conditions, the line cannot eliminate its own icing through the thermal effect of the load current, but this does not affect the normal power supply to the LV side. The icing and current status of the line can be continuously monitored. When the icing exceeds the conductor design value, such as... Figure 7 The diagram shown is a schematic of the de-icing device connected to the autotransformer.

[0143] Combination Figure 7 and Figure 1 At connection points 3 and 4, a potential difference of 10.4 kV is formed between the high-voltage side U1 and the low-voltage side U2 of the autotransformer. For conductor L_1, the current I1 is 1000 A at this point, which allows for rapid de-icing of the conductor. The capacity required for de-icing is 18 MW, while the capacity required for a 448.5 Ω load is... During normal ice melting, the total current IS1 of the power supply is 236A.

[0144] Because autotransformers for ice melting share a single winding on both the primary and secondary sides, with a turns ratio of N1 / N2, the difference in turns ratio between the primary and secondary windings can be even smaller for short-distance ice melting lines requiring high current. The capacity of an autotransformer can be defined in two ways: one is ice melting capacity, where the current is large but mainly flows through the non-shared portion of the primary winding. The number of windings in this non-shared portion is affected by the turns ratio; the smaller the turns ratio, the lower the manufacturing cost of the non-shared portion of the coil. The other is load capacity, where the ice melting device is activated only when the load current is low, so the current in the shared portion of the primary and secondary windings is relatively small, having little impact on the transformer's manufacturing cost. Because the ice melting currents in the shared coils of the autotransformer cancel each other out, using autotransformers as a three-phase conductor online ice melting method is highly technically and economically advantageous.

[0145] It should be noted that the above calculations do not take into account the voltage drop caused by the impedance of the line and transformer. The actual transformation ratio and capacity design of the autotransformer depend on the specific engineering design, but its de-icing device relies on the three-phase overhead line uninterrupted de-icing device and control method provided by this invention, which are all within the protection scope of this invention.

[0146] It should be noted that the three-phase overhead line uninterrupted de-icing device and control method provided by this invention can also be replaced by a reactive power compensation device to replace the power supply, using reactive current to achieve conductor de-icing. Specifically, power can be applied to both ends of the conductor, allowing current to flow in a specific section (i.e., the section to be de-iced) to generate heat and achieve conductor de-icing without affecting the normal power supply of other lines.

[0147] Each of the above-described method embodiments, or various possible implementations of each method embodiment, can be executed individually or in combination of any two or more. The specific implementation can be determined according to actual usage requirements, and the present invention does not impose any restrictions on this.

[0148] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0149] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A three-phase overhead line uninterrupted de-icing device, characterized in that, An ice-melting device for overhead lines containing three-phase conductors, applicable to sections requiring de-icing, comprising: The conductors in the section to be melted are constructed as a first transmission branch and a second transmission branch connected in parallel. The bus tie switch, located on the second transmission branch, is used to disconnect the second transmission branch when the conductor is de-iced. A switch group is used to electrically connect the high-voltage side terminals and the low-voltage side terminals of the autotransformer to the two ends of the second transmission branch when the bus tie switch is open. An autotransformer is used to obtain electrical energy from the overhead line.

2. The three-phase overhead line uninterrupted de-icing device according to claim 1, characterized in that, The overhead line is a three-phase overhead line, and the three-phase overhead line uninterrupted de-icing device is set for each of the three phases.

3. The three-phase overhead line uninterrupted de-icing device according to claim 2, characterized in that, A three-phase autotransformer bank is formed by the corresponding autotransformers of each of the three phases.

4. The three-phase overhead line uninterrupted de-icing device according to claim 2, characterized in that, The overhead line also includes a ground wire, and the three-phase overhead line uninterrupted de-icing device also includes a ground wire de-icing unit. The ground wire de-icing unit includes: An independent secondary winding is connected to the ground wire de-icing switch of the ground wire, and the independent secondary winding is electrically isolated from the winding of the autotransformer.

5. The three-phase overhead line uninterrupted de-icing device according to claim 4, characterized in that, The grounding de-icing switch includes at least one of the following: An AC circuit breaker used to switch the connection between the independent secondary winding and the ground wire; Disconnecting switch used to switch the connection between the independent secondary winding and the ground wire.

6. The three-phase overhead line uninterrupted de-icing device according to any one of claims 1 to 5, characterized in that, The switch group includes a high-voltage side switch and a low-voltage side switch of the autotransformer, and the switch group also includes at least one of a disconnecting switch and a grounding switch.

7. The three-phase overhead line uninterrupted de-icing device according to any one of claims 1 to 5, characterized in that, The three-phase overhead line uninterrupted de-icing device also includes a measuring unit and a controller; The measurement unit is used to collect data on line icing. The controller is used to perform the opening and closing operations of the bus tie switch and the switch group based on the line icing data.

8. The three-phase overhead line uninterrupted de-icing device according to any one of claims 1 to 5, characterized in that, The second transmission branch is an auxiliary conductor that is physically separate from and parallel to the first transmission branch.

9. A method for controlling de-icing of three-phase overhead lines without power interruption, applied to the three-phase overhead line de-icing device as described in any one of claims 1 to 8, characterized in that, include: When it is necessary to melt the ice on the conductors in the section to be melted, disconnect the bus tie switch set on the second transmission branch and close the switch group. Connect the high-voltage side terminal and the low-voltage side terminal of the autotransformer to the two ends of the second transmission branch respectively. In this way, a melting current is generated in the second transmission branch, and the first transmission branch connected in parallel with the second transmission branch continues to supply power downstream. After the conductors have melted, disconnect the switch group and close the bus tie switch to restore the parallel power transmission state.

10. The method for controlling de-icing of three-phase overhead lines without power interruption according to claim 9, characterized in that, The three-phase overhead line uninterrupted de-icing control method also includes: By controlling the ground wire de-icing switch, the independent secondary winding provides de-icing current to the ground wire.

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