On-load line ice melting structure and control system based on reactive compensation principle

Abstract

The utility model relates to the technical field of power distribution line ice melting, in particular to an on-load line ice melting structure and a control system based on a reactive compensation principle, which comprises a line load comprising N sections of sub-lines connected in sequence, and N is a natural number greater than or equal to 1; and the compensation module comprises a reactive power supply and a reactive load, the reactive power supply is connected to the front end of each section of sub-circuit, and the reactive load is connected to the tail end of each section of sub-circuit. The beneficial effects of the utility model are that the operation strategy is adjusted in real time according to the operation condition of the line, four control modes including a line protection mode, an ice melting mode, a voltage regulation mode and a standby mode are provided, the voltage stabilization characteristics of the capacitor and the reactance can be fully utilized, and the ice melting function of the line can be realized under the condition that the line is not stopped.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of distribution line ice melting, especially a load line ice melting structure and control system based on reactive compensation principle. BACKGROUND

[0002] In recent years, the ice disaster of power grid industry occurs more frequently, and the line icing range is gradually increasing, extending from the previous high altitude to low altitude area, and the icing intensity in some areas is obviously improved. In some areas, the traditional distribution network without icing and light icing area begins to appear moderate and heavy icing phenomenon, which exceeds the anti-icing defense standard; at the same time, the overall defense standard of distribution line is low, and serious icing is prone to cause problems such as pole overturning and wire breaking.

[0003] At present, the common ice melting technologies mainly include mechanical deicing, thermal ice melting and natural ice melting. For the power system, the thermal ice melting technology is a relatively ideal scheme, which melts ice by using the Joule heat generated by the current flowing through the distribution line. The most common methods are alternating current short circuit ice melting and direct current short circuit ice melting. However, these two methods must be carried out under the condition of line outage, and are mainly used for 110kV and above transmission lines, which has low practicability for distribution network. Therefore, a load line ice melting structure and control system based on reactive compensation principle are designed to solve the power outage problem during ice melting, reduce the power outage accidents caused by ice disaster, and ensure the continuity and reliability of power supply. SUMMARY

[0004] This section aims to outline some aspects of the embodiments of the utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the utility model name to avoid obscuring the purpose of this section, the abstract of the specification and the utility model name. Such simplifications or omissions cannot be used to limit the scope of the utility model.

[0005] In view of the above or the problem that the line deicing needs to be stopped in the prior art, the utility model is proposed.

[0006] Therefore, the purpose of the utility model is to provide a load line ice melting structure based on reactive compensation principle.

[0007] To solve the above technical problems, the utility model provides the following technical scheme: a load line ice melting structure based on reactive compensation principle, which comprises a line load and N segments of sub-lines connected in sequence, wherein N is a natural number greater than or equal to 1; a compensation module comprising a reactive power source and a reactive load, the reactive power source being connected to the front end of each segment of sub-line, and the reactive load being connected to the end of each segment of sub-line.

[0008] As a preferred embodiment of the load-bearing line de-icing structure based on the reactive power compensation principle of this utility model, a first transformer is provided at the front end of the line load.

[0009] As a preferred embodiment of the load-bearing line de-icing structure based on the reactive power compensation principle of this utility model, wherein: the reactive power supply is connected to the secondary side of the second transformer, and the primary side of the second transformer is connected to the front end of the sub-line through the first circuit breaker.

[0010] As a preferred embodiment of the load-bearing line de-icing structure based on the reactive power compensation principle of this utility model, wherein the reactive power source is a voltage-controlled capacitor.

[0011] As a preferred embodiment of the de-icing structure for a loaded line based on the principle of reactive power compensation of this utility model, wherein the reactive load is an adjustable reactor.

[0012] As a preferred embodiment of the load-bearing line de-icing structure based on the reactive power compensation principle of this utility model, wherein the reactive load is connected to the end of the sub-line through a second circuit breaker.

[0013] The beneficial effects of this utility model are as follows: This utility model is used to solve the problem of coordinated control of power supply, load, and voltage regulator in the scenario of load-bearing ice melting in power distribution networks; it solves the problem of coordinated control of power supply, load, and voltage regulator in the technology of using reactive current for load-bearing ice melting. The operating strategy is adjusted in real time according to the line's operating conditions, with four control modes: line protection mode, ice melting mode, voltage regulation mode, and standby mode. It can fully utilize the voltage stabilizing characteristics of capacitors and reactants, and in addition to achieving the function of line ice melting without line interruption, it can also improve the line's power quality and stabilize the line voltage.

[0014] In practical use, there is still the issue of how to adjust the line de-icing current.

[0015] To solve the above-mentioned technical problems, this utility model also provides the following technical solution: a control system includes a load line de-icing structure based on the principle of reactive power compensation, and a control module including a main control unit, a voltage regulation control unit, and a slave control unit. The main control unit controls the connection and disconnection of the reactive power supply and the tap adjustment of the second transformer; the voltage regulation control unit controls the tap adjustment of the first transformer; and the slave control unit controls the connection and disconnection of the reactive load.

[0016] In a preferred embodiment of the control system of this utility model, the main control unit controls the input and output of reactive power by controlling the opening and closing of the first circuit breaker.

[0017] In a preferred embodiment of the control system of this utility model, the slave control unit controls the connection and disconnection of reactive loads by opening and closing the second circuit breaker.

[0018] In a preferred embodiment of the control system of this utility model, the main control unit, the voltage regulation control unit, and the slave control unit communicate with each other through a communication module.

[0019] The beneficial effects of this utility model are: by setting up a control module, this utility model can adjust the de-icing current in real time according to the line conditions, so as to ensure the de-icing effect of the line. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them:

[0021] Figure 1 This is a schematic diagram of ice melting under load using a reactive power compensation device in this utility model.

[0022] Figure 2 This is a schematic diagram of the reactive power compensation power supply device in a specific embodiment of this utility model.

[0023] Figure 3 This is a schematic diagram of the line voltage regulator in a specific embodiment of this utility model.

[0024] Figure 4 This is a schematic diagram of the reactive load device in a specific embodiment of this utility model.

[0025] Figure 5 This is a diagram showing the operating status of adding a reactive load separately at the end of the line in this utility model. Detailed Implementation

[0026] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0029] Example 1

[0030] Reference Figure 1 This is the first embodiment of the present utility model. This embodiment provides a load line de-icing structure based on the principle of reactive power compensation, which can achieve the effect of de-icing without stopping the line. It includes a line load 100 and a compensation module 200. By setting the compensation module 200 to generate de-icing current, the ice on the line load 100 is melted.

[0031] Specifically, line load 100 includes N segments of sub-lines connected in sequence, where N is a natural number greater than or equal to 1; line load 100 is a power distribution line, and a sub-line is any one of the segments on line load 100.

[0032] Furthermore, the compensation module 200 includes a reactive power supply 201 and a reactive load 202. The reactive power supply 201 is connected to the front end of each sub-line segment, and the reactive load 202 is connected to the end of each sub-line segment. Adding the reactive load 202 at the end of the sub-line ensures that the current required for ice melting at the end of the sub-line is met. While adding a reactive load alone can effectively increase the ice melting current, it significantly impacts the voltage drop and power distribution of the line, leading to severe low voltage and overload on the substation's outgoing lines. Therefore, adding the reactive power supply 201 at the front end of the sub-line provides the reactive current required for ice melting, ensuring that the line segment requiring ice melting at its end meets the melting conditions without affecting other users on the line.

[0033] Operation process: Connect reactive power supply 201 to the front end of the sub-line of line load 100, and connect reactive load 202 to the end of the sub-line. Reactive load 202 adds de-icing current to the line, and reactive power supply 201 provides the reactive current required for de-icing, so that the line at the end of the line that needs de-icing meets the de-icing conditions, and does not affect other users on the line.

[0034] In summary, by setting the line load 100 and the compensation module 200, the de-icing current and reactive current can be increased. This allows for the formation of a reactive current circulation between the reactive power source and the reactive load without interrupting line operation. By utilizing the thermal effect of the current flowing through the overhead line, the line de-icing function can be achieved.

[0035] Example 2

[0036] ReferenceFigures 1-5 This is the second embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a further optimization of the de-icing structure for a loaded line based on the reactive power compensation principle, solving the problem of how to perform de-icing. It includes a first transformer 101 installed at the front end of the line load 100. The first transformer 101 is added in the middle of the line to boost the voltage to bring it within the acceptable range.

[0037] Specifically, reactive power supply 201 is connected to the secondary side of the second transformer 203, and the primary side of the second transformer 203 is connected to the front end of the sub-line via the first circuit breaker 204. Reactive power supply 201 is connected to the on-load tap changer, i.e., the second transformer 203. By connecting the primary side of the on-load tap changer to the line, the output voltage of the secondary side can be adjusted by regulating the switch on one side of the on-load tap changer, thereby adjusting the capacity of reactive power supply 201. The fineness of the adjustment depends on the tap position of the on-load tap changer. Because the voltage difference between the two taps is small, inrush current can be effectively avoided; at the same time, frequent switching of capacitors is unnecessary, extending the product's service life. Simultaneously, reactive power supply 201 is connected to the secondary side of the second transformer 203 via a reactor and a switch. The primary side of the second transformer 203 is connected to the first circuit breaker 204 via a current transformer (CT), and the reactive load 202 is connected to the second circuit breaker 205 via a CT.

[0038] Furthermore, the reactive power supply 201 is a voltage-controlled capacitor. As a reactive power supply connected to the sub-circuit, the voltage-controlled reactive power compensation capacitor can improve the power quality of the line and stabilize the line voltage.

[0039] Furthermore, the reactive load 202 is an adjustable reactor. When connected as a reactive load to a sub-circuit, the adjustable reactor increases the de-icing current of the line, thus meeting the line's de-icing requirements.

[0040] Preferably, the reactive load 202 is connected to the end of the sub-line via the second circuit breaker 205. The first circuit breaker 204 and the second circuit breaker 205 are used to control the connection or disconnection of the reactive power source 201 and the reactive load 202.

[0041] Operation process: Before the overhead line needs de-icing, the reactive power supply and reactive load are at their minimum settings, and the line voltage regulating unit is at its rated setting, without adjusting the line voltage. When the line needs to enter the de-icing state, the adjustable reactor increases the de-icing current in the line, and the voltage-controlled reactive power compensation capacitor increases the reactive current in the line, improving the power quality of the line and stabilizing the line voltage.

[0042] In summary, by setting adjustable reactors and voltage-controlled reactive power compensation capacitors, the de-icing current and reactive current in the line can be increased, enabling the line to de-ic itself without interrupting operation.

[0043] Example 3

[0044] Reference Figures 1-5 This is the third embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a control system that solves the problem of how to collect the operating status and icing conditions of the line. It includes a control module 300, which includes a main control unit 301, a voltage regulation control unit 302, and a slave control unit 303. The main control unit 301 controls the connection and disconnection of the reactive power supply 201 and the tap adjustment of the second transformer 203; the voltage regulation control unit 302 controls the tap adjustment of the first transformer 101; and the slave control unit 303 controls the connection and disconnection of the reactive load 202. The main control unit 301 receives data collected by the voltage regulating control unit 302 and the slave control unit 303, determines the current operating status and icing condition of the overhead line, and uses this as the starting criterion for the de-icing equipment. Based on the data collected by the voltage regulating control unit 302 and the slave control unit 303, the main control unit 301 determines the current operating status of the overhead line and adjusts the line voltage and de-icing current in real time according to the operating status. Based on the collected data, the main control unit 301 judges the de-icing effect and adjusts the operating strategy in real time, which includes four modes: line protection mode, de-icing mode, voltage regulating mode, and standby mode.

[0045] Specifically, the main control unit 301 controls the connection and disconnection of the reactive power supply 201 by controlling the opening and closing of the first circuit breaker 204. When de-icing is required, the main control unit 301 controls the opening and closing of the first circuit breaker 204 to connect or disconnect the reactive power supply 201.

[0046] Furthermore, the slave control unit 303 controls the connection and disconnection of the reactive load 202 by opening and closing the second circuit breaker 205. The master control unit 301 receives the data transmitted by the slave control unit 202, determines whether the reactive load 202 needs to be connected, and issues a command to the slave control unit 303 to control the connection or disconnection of the reactive load 202.

[0047] Furthermore, the main control unit 301 communicates with the voltage regulating control unit 302 and the slave control unit 303 via a communication module 400. The slave control unit 303 receives the circuit breaker's operating data via an RJ45 network. Medium-voltage carrier or 4G is used for communication between the slave control unit 303, the voltage regulating control unit 302, and the main control unit 301. The communication module also includes RS-485 for image transmission and viewing the de-icing effect.

[0048] Operation process: The master control unit 301 sends a control command to the slave control unit 303. The slave control unit 303 controls the activation of the reactive load 202 and uploads a success or failure signal to the master control unit 301. The master control unit 301 receives the activation signal of the reactive load 202 and controls the activation of the reactive power supply 201. The master control unit 301 determines the required reactive power based on the line de-icing current and transmits the required load capacity to the slave control unit 303. The slave control unit 303 controls the reactive load 202 to adjust to the corresponding level according to the required load capacity and transmits the level signal back to the master control unit 301. The master control unit 301 controls the reactive power supply 201 to adjust to the corresponding level according to the required capacity of the reactive load 202.

[0049] In summary, by setting up a main control unit 301, a voltage regulation control unit 302, and a slave control unit 303, the operating strategy can be adjusted in real time according to the line's operating conditions. There are four control modes: line protection mode, de-icing mode, voltage regulation mode, and standby mode. This can make full use of the voltage stabilizing characteristics of capacitors and reactors to achieve the line de-icing function without stopping the line.

[0050] Working principle: Before the overhead line needs de-icing, the reactive power supply and reactive load are both at their minimum settings, and the line voltage regulation unit is at its rated setting, without adjusting the line voltage. When the main control unit 301 determines, based on the collected data, that the line needs to enter the de-icing state,

[0051] The main control unit 301 sends a command through the communication module, instructing the slave control unit 303 to control the circuit breaker QF2 to close and activate the reactive load 400.

[0052] The slave control unit 303 issues a closing command and uploads the received closing success or failure signal to the master control unit 301 through the communication module.

[0053] When the main control unit 301 receives the reactive load connection signal, it issues a closing command to QF1 to connect the reactive power supply 500.

[0054] The main control unit 301 determines the required reactive power based on the line de-icing current and sends the required load capacity QL to the slave control unit 303 via the communication module. The calculation method is as follows:

[0055]

[0056] The slave control unit 303 controls the adjustable reactor to the corresponding position according to the required input capacity and transmits the position signal back to the master control unit 301. The master control unit 301 controls the reactive power supply 500 to the corresponding position according to the required input capacity of the reactive load 400.

[0057] Based on the line voltage data, the main control unit 301 calculates the voltage value that the gear adjustment unit needs to adjust and sends it to the voltage regulation control unit 302. The relationship between voltage drop, line parameters, and power is shown below:

[0058]

[0059]

[0060] The voltage regulating control unit 302 controls the voltage regulating transformer to the required level according to the instructions sent by the main control unit 301.

[0061] In most cases, the rated current of a 10kV pole-mounted circuit breaker is 630A. Based on this, the maximum power allowed to flow through a 10kV line is... However, in reality, for common 10kV wire diameters, whether it's the bare conductor of the LGJ type or the common 10kV three-core cable mentioned in Table C.0.3 of Appendix GB 50217, it doesn't support such a large current carrying capacity at 20℃. Therefore, for common 10kV lines, a transmission power of 11MVA is difficult to achieve. A preliminary estimate of the maximum load for different cable types needs to be made based on the cable type and temperature, as shown in the table below:

[0062] Table 1 Apparent Power Calculated Based on Current Carrying Capacity

[0063]

[0064] Considering the relationship between current carrying capacity and de-icing current, the equipment cannot reach the maximum de-icing current during normal operation. Prolonged overload operation may cause FTU alarms or tripping, which does not meet the requirements for de-icing under load. Therefore, when configuring reactive power loads, the line current after the equipment is put into operation should be greater than the minimum de-icing current and less than or equal to the line current carrying capacity. Considering that the line current carrying capacity will be appropriately increased at low temperatures, the capacity of the reactive power supply cannot be determined according to the temperature at 25°C. Some margin needs to be reserved. Therefore, when the line is unloaded, the capacity of the equipment can be set to three levels: 5MkVA, 7.5MkVA, and 10MkVA. If the line itself already has some current, it is only necessary to reduce the required power.

[0065] In this invention, the main control unit 301, voltage regulation control unit 302, and slave control unit 303 are also connected to multiple sets of sensors for collecting line status data. The voltage monitoring module monitors the voltage at both ends of the line to be melted in real time, ensuring that the node voltage does not exceed the lower limit when the system is operating in melting mode. The current monitoring module consists of two parts, installed on the equipment side and the line side respectively. The current monitoring module installed on the line side monitors the melting line current in real time, while the current monitoring module installed on the equipment side monitors the reactive current provided by the reactive power supply and the reactive current absorbed by the reactive load, thereby ensuring that the line current reaches the melting current and the equipment operates normally. The meteorological monitoring module includes ambient temperature, humidity, wind speed, and wind direction, installed on the tower of the melting equipment, to monitor the meteorological environment around the melting equipment and serve as a criterion for starting and stopping the melting equipment. The cable surface temperature monitoring module includes a wireless cable temperature monitoring module to determine the cable melting rate, serving as a basis for judging the melting rate. The video monitoring module includes a pan-tilt unit, a zoomable high-definition camera, a power module, etc., serving as a basis for judging the melting effect.

[0066] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (variations in installation arrangement, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of this utility model. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure performing the function described herein, and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of this utility model. Therefore, this invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0067] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments may be omitted.

[0068] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those of ordinary skill in the art who benefit from this disclosure, the development effort will be a routine task in design, manufacturing, and production without requiring extensive experimentation.

[0069] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A load-bearing line de-icing structure based on the principle of reactive power compensation, characterized in that: include, The line load (100) includes N sequentially connected sub-lines, where N is a natural number greater than or equal to 1; The compensation module (200) includes a reactive power supply (201) and a reactive load (202). The reactive power supply (201) is connected to the front end of each sub-line, and the reactive load (202) is connected to the end of each sub-line.

2. The load-bearing line de-icing structure based on the reactive power compensation principle as described in claim 1, characterized in that: A first transformer (101) is provided at the front end of the line load (100).

3. The load-bearing line de-icing structure based on the reactive power compensation principle as described in claim 2, characterized in that: The reactive power supply (201) is connected to the secondary side of the second transformer (203), and the primary side of the second transformer (203) is connected to the front end of the sub-line through the first circuit breaker (204).

4. The de-icing structure for load-bearing lines based on the reactive power compensation principle as described in claim 3, characterized in that: The reactive power source (201) is a voltage-controlled capacitor.

5. The de-icing structure for loaded power lines based on the reactive power compensation principle as described in claim 4, characterized in that: The reactive load (202) is an adjustable reactor.

6. The de-icing structure for load-bearing lines based on the reactive power compensation principle as described in claim 5, characterized in that: The reactive load (202) is connected to the end of the sub-line via the second circuit breaker (205).

7. A control system, characterized in that: Including the de-icing structure for loaded power lines based on the reactive power compensation principle as described in any one of claims 1 to 6, and The control module (300) includes a main control unit (301), a voltage regulation control unit (302), and a slave control unit (303). The main control unit (301) controls the connection and disconnection of the reactive power supply (201) and the gear adjustment of the second transformer (203). The voltage regulation control unit (302) controls the gear adjustment of the first transformer (101). The slave control unit (303) controls the connection and disconnection of the reactive load (202).

8. The control system as described in claim 7, characterized in that: The main control unit (301) controls the connection and disconnection of the reactive power supply (201) by controlling the opening and closing of the first circuit breaker (204).

9. The control system as described in claim 8, characterized in that: The slave control unit (303) controls the connection and disconnection of the reactive load (202) by opening and closing the second circuit breaker (205).

10. The control system as described in claim 9, characterized in that: The main control unit (301), the voltage regulation control unit (302), and the slave control unit (303) communicate with each other through a communication module (400).

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