Online ice melting system

Abstract

The embodiment of the invention discloses an online ice melting system, which comprises a first active filter, a second active filter and a harmonic power supply, the first active filter is connected in series in a first non-icing line, and the first non-icing line is connected with the head end of the icing line; the second active filter is connected in series in a second non-icing line, and the second non-icing line is connected with the tail end of the icing line; the first end of the harmonic power supply is connected with the head end of the iced line, and the second end of the harmonic power supply is connected with the second non-iced line; the harmonic power supply and the ice-coated line form an ice-melting loop, the harmonic power supply is used for generating ice-melting current, the first active filter is used for attenuating ice-melting current of the first non-ice-coated line, and the second active filter is used for attenuating ice-melting current of the second non-ice-coated line. By adopting the technical scheme, the power failure of the line during the ice melting period can be avoided, the bottleneck that the power failure is required during the original ice melting operation is broken through, and the power supply reliability of the power grid is improved.

Description

Technical Field

[0001] The invention relates to the technical field of line ice melting, and in particular to an online ice melting system. Background Art

[0002] The medium voltage 10kV distribution network is widely used. According to statistics, the electric energy supplied to users through the medium voltage distribution network accounts for 70% to 80% of the total power supply. Due to the short distribution network lines and small conductor resistance, the existing DC or industrial frequency AC ice melting methods require a large ice melting current. In southern my country, the distribution network is covered with ice in a wide range in winter, and it is difficult to melt the ice, resulting in frequent line breaks, pole collapses, and ice flash tripping accidents. Therefore, it is of great significance to explore new distribution network ice melting methods.

[0003] At present, the main anti-icing technologies for distribution networks include mechanical de-icing, electric thermal ice melting, chemical coating anti-icing, etc., among which the electric thermal ice melting method is widely used. Electric thermal ice melting is divided into DC short-circuit ice melting method, industrial frequency AC short-circuit ice melting method and high-frequency ice melting. Since high-frequency current has the characteristics of skin effect, which increases the equivalent resistance of the wire, and the ice coating produces dielectric heat loss under the action of the high-frequency electric field, the high-frequency ice melting method has the advantage of high thermal efficiency. However, the existing high-frequency ice melting method requires short circuit, which affects the electricity consumption of nearby residents. Summary of the invention

[0004] The embodiment of the present invention provides an online ice melting system, which can realize non-stop ice melting of distribution network lines based on a closed loop formed by a harmonic power supply and an ice-covered line and an active filter.

[0005] In a first aspect, an embodiment of the present invention provides an online ice melting system, comprising a first active filter, a second active filter and a harmonic power supply;

[0006] The first active filter is connected in series to a first non-icing circuit, and the first non-icing circuit is connected to the head end of the ice-covered circuit; the second active filter is connected in series to a second non-icing circuit, and the second non-icing circuit is connected to the end of the ice-covered circuit;

[0007] The first end of the harmonic power supply is connected to the head end of the ice-covered line, and the second end of the harmonic power supply is connected to the second non-ice-covered line;

[0008] The harmonic power supply and the ice-covered line form an ice-melting circuit, wherein the harmonic power supply is used to generate an ice-melting current, the first active filter is used to attenuate the ice-melting current of the first non-ice-covered line, and the second active filter is used to attenuate the ice-melting current of the second non-ice-covered line.

[0009] Optionally, the first end of the harmonic power supply includes a first output end, a second output end and a third output end, and the first output end, the second output end and the third output end are respectively connected to the three phases of the head end of the ice-covering circuit;

[0010] The second end of the harmonic power supply includes a first input end, a second input end and a third input end, and the first input end, the second input end and the third input end are respectively connected to the three phases of the second non-icing line.

[0011] Optionally, the first active filter includes a first transformer and a first inverter, wherein the first transformer includes a first primary winding and a first secondary winding;

[0012] The first primary winding is connected in series in the first non-icing circuit;

[0013] A first end of the first secondary winding is connected to a first output end of the first inverter, and a second end of the first secondary winding is connected to a second output end of the first inverter.

[0014] Optionally, the first active filter further includes a first filter reactor;

[0015] The first end of the first filter reactor is connected to the second end of the first secondary winding, and the second end of the first filter reactor is connected to the second output end of the first inverter.

[0016] Optionally, the online ice melting system further includes a first control module;

[0017] The first control module is connected to the control end of the first inverter.

[0018] Optionally, the online ice melting system further includes a first detection module;

[0019] The input end of the first detection module is connected to the three phases of the first non-icing circuit, and the output end is connected to the first control module.

[0020] Optionally, the second active filter includes a second transformer and a second inverter, wherein the second transformer includes a second primary winding and a second secondary winding;

[0021] The second primary winding is connected in series in the second non-icing circuit;

[0022] A first end of the second secondary winding is connected to a first output end of the second inverter, and a second end of the second secondary winding is connected to a second output end of the second inverter.

[0023] Optionally, the second active filter further includes a second filter reactor;

[0024] The first end of the second filter reactor is connected to the second end of the second secondary winding, and the second end of the second filter reactor is connected to the second output end of the second inverter.

[0025] Optionally, the online ice melting system further includes a second control module;

[0026] The second control module is connected to the control end of the second inverter.

[0027] Optionally, the online ice melting system further includes a second detection module;

[0028] The input end of the second detection module is connected to the three phases of the second non-icing circuit, and the output end is connected to the second control module.

[0029] In this embodiment, the harmonic power supply and the ice-covered line form an ice-melting circuit, the harmonic power supply is used to generate a harmonic current for ice melting, the ice-covered line is melted by the harmonic current, and the ice-melting current in the first non-iced line and the second non-iced line is respectively attenuated by a first active filter connected in series with the first non-iced line and a second active filter connected in series with the second non-iced line, so that the harmonic current for ice melting can only flow in the ice-melting circuit to melt the ice, avoiding the influence of the ice-melting current on the non-iced line, realizing online ice melting of the ice-covered line, breaking through the bottleneck of power outage required for the original ice melting operation, effectively reducing the loss of line power outage caused by icing and line power outage caused by melting, which is beneficial to ensuring the power supply at the load end of the distribution network and greatly improving the reliability of power supply of the power grid.

[0030] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 is a structural schematic diagram of an online ice melting system provided by an embodiment of the present invention;

[0033] Figure 2 It is a partial structural schematic diagram of an online ice melting system provided by an embodiment of the present invention;

[0034] Figure 3is a partial structural schematic diagram of another online ice melting system provided by an embodiment of the present invention;

[0035] Figure 4 It is a partial structural schematic diagram of another online ice melting system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0037] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0038] In the prior art, in 10kV transmission lines, the main choices for conductors are aluminum core cross-linked polyethylene insulated overhead circuits and copper core aluminum stranded wires. In old industrial areas with many trees or high metal dust pollution, salt fog areas, areas with frequent lightning, and areas with typhoon disasters, aluminum core cross-linked polyethylene insulated overhead circuits are usually used to ensure the safety and reliability of transmission line transmission. In most other cases, copper core aluminum stranded wires are basically used in consideration of economic benefits. In the case where ice has already formed on the line, there are two main ice melting methods: AC short-circuit ice melting technology and DC short-circuit ice melting technology, which greatly alleviate the problem of grid ice, but it still requires power outages during the ice melting period. While solving the ice problem, it also reduces the effective power consumption rate to a certain extent. Unlike the ice melting of the main grid transmission lines, the 10kV distribution network is directly connected to the user side. Since the conditions of the distribution lines are complex and changeable, their lines account for a large proportion. Since the voltage level of the distribution network in the power grid is not high, the staff do not pay enough attention to the protection of its lines, which makes the distribution network itself have a low level of natural disaster prevention. The distribution network areas that are prone to ice are often located in mountainous areas with high altitudes and narrow and rugged mountain roads. Therefore, compared with the main grid, the distribution network needs more effective de-icing and ice melting methods.

[0039] Figure 1 is a structural diagram of an online ice melting system provided by an embodiment of the present invention. This embodiment can be applied to the case of melting ice on ice-covered lines of a distribution network, such as Figure 1 As shown, the online ice melting system 100 includes: a first active filter 1, a second active filter 2 and a harmonic power supply 3; the first active filter 1 is connected in series to the first non-icing line 4, and the first non-icing line 4 is connected to the head end of the ice-covered line 5; the second active filter 2 is connected in series to the second non-icing line 6, and the second non-icing line 6 is connected to the end of the ice-covered line 5; the first end of the harmonic power supply 3 is connected to the head end of the ice-covered line 5, and the second end of the harmonic power supply 3 is connected to the second non-icing line 6; the harmonic power supply 3 and the ice-covered line 5 form an ice melting circuit, wherein the harmonic power supply 3 is used to generate an ice melting current, the first active filter 1 is used to attenuate the ice melting current of the first non-icing line 4, and the second active filter 2 is used to attenuate the ice melting current of the second non-icing line 6.

[0040] Specifically, the second end of the harmonic power supply 3 is connected to the second non-icing line 6, and the original three-phase current of the second ice-covered line 6 is drawn out to provide stable electric energy for the harmonic power supply 3. The harmonic power supply 3 generates a corresponding harmonic current according to the required ice-melting current and outputs it to the head end of the ice-covered line 5 through the second end, thereby forming an ice-melting circuit consisting of the harmonic power supply 3 and the ice-covered line 5, thereby realizing the ice melting of the ice-covered line 5.

[0041] The first active filter 1 is connected in series with the first non-icing line 4 connected to the head end of the ice-covered line 5. When the harmonic current generated by the harmonic power source 3 flows into the original three-phase circuit of the distribution network through the connection point a, the first active filter 1 adjusts the size of its own equivalent impedance so that it presents zero impedance to the fundamental wave of the original three-phase circuit and high impedance to the harmonic current, thereby attenuating the harmonic current in the first non-icing line 4 and forcing the harmonic current generated by the harmonic power source 3 to flow from the connection point a to the ice-covered line 5. The second active filter 2 is connected in series with the second non-icing line 4 connected to the end of the ice-covered line 5. When the harmonic current generated by the harmonic power source 3 passes through the connection point b, the second active filter 2 adjusts the size of its own equivalent impedance so that it presents zero impedance to the fundamental wave of the original three-phase circuit and high impedance to the harmonic current, thereby attenuating the harmonic current in the second non-icing line 6 and forcing the harmonic current generated by the harmonic power source 3 to flow from the connection point b to the ice melting circuit. The first active filter 1 and the second active filter 2 respectively attenuate the influence of the ice-melting current on the first non-iced line 4 and the second non-iced line 6. On the one hand, the background harmonic voltage from the grid side can be isolated, and on the other hand, the harmonic current injected into the grid by the harmonic power supply 3 for ice melting can be forced to flow into the ice-melting circuit, so as to realize online ice melting of the ice-covered line 5 without affecting the fundamental current of the original three-phase circuit of the grid.

[0042] In this embodiment, the harmonic power supply and the ice-covered line form an ice-melting circuit, the harmonic power supply is used to generate a harmonic current for ice melting, the ice-covered line is melted by the harmonic current, and the ice-melting current in the first non-iced line and the second non-iced line is respectively attenuated by a first active filter connected in series with the first non-iced line and a second active filter connected in series with the second non-iced line, so that the harmonic current for ice melting can only flow in the ice-melting circuit to melt the ice, avoiding the influence of the ice-melting current on the non-iced line, realizing online ice melting of the ice-covered line, breaking through the bottleneck of power outage required for the original ice melting operation, effectively reducing the loss of line power outage caused by icing and line power outage caused by melting, which is beneficial to ensuring the power supply at the load end of the distribution network and greatly improving the reliability of power supply of the power grid.

[0043] Based on the above embodiments, Figure 2 is a partial structural diagram of an online ice melting system provided by an embodiment of the present invention. Figure 2 The structure of the harmonic power supply is explained. Figure 2 As shown, the first end of the harmonic power supply 3 includes a first output terminal c, a second output terminal d and a third output terminal e, and the first output terminal c, the second output terminal d and the third output terminal e are respectively connected to the three phases of the head end of the ice-covered line 5; the second end of the harmonic power supply 3 includes a first input terminal f, a second input terminal g and a third input terminal h, and the first input terminal f, the second input terminal g and the third input terminal h are respectively connected to the three phases of the second non-ice-covered line 6.

[0044] Specifically, refer to Figure 2 The harmonic power supply 3 is connected to the three phases of the second non-icing line 6 through the first input terminal f, the second input terminal g and the third input terminal h, so that the original three-phase current of the second ice-covered line 6 is introduced into the harmonic power supply 3, providing stable electric energy for the harmonic power supply 3. The harmonic power supply 3 generates the corresponding harmonic current according to the required ice-melting current, and outputs the harmonic current to the head end of the ice-covered line 5 through the first output terminal c, the second output terminal d and the third output terminal e, thereby forming an ice-melting circuit consisting of the harmonic power supply 3 and the ice-covered line 5. During the ice-melting operation, the harmonic power supply 3 can be equivalent to a controlled current source connected in series to the ice-melting circuit. The size of the ice-melting current is controlled by the harmonic power supply 3, which can effectively adjust the harmonic current of the line to achieve the ice-melting operation of the ice-covered line 5.

[0045] Among them, the harmonic power supply 3 is composed of 18 insulated gate bipolar transistors and 18 diodes, such as Figure 2As shown, multiple groups of bidirectional switches are formed by insulated gate bipolar transistors, the input power supply of the harmonic power supply 3 is the original three-phase alternating current of the second non-ice-covered line 6, and the bidirectional switch of the main power circuit is formed by two insulated gate bipolar transistors with common emitters connected in reverse series, which can realize the function of bidirectional conduction of the switch. The modulation strategy of the indirect space vector algorithm is adopted, and the voltage waveform of the required amplitude and frequency is synthesized by the input voltage vector, so as to meet the demand of the ice-melting current, and the harmonic current that can achieve the ice-melting effect on the ice-covered line 5 is output. The first output terminal c, the second output terminal d and the third output terminal e are connected to the head end of the ice-covered line 5, and the ice-melting current is directly connected to the ice-covered line 5 to realize three-phase variable frequency ice-melting, without any DC link or large energy storage element, which is helpful to realize the design of a compact and lightweight variable frequency ice-melting system. Exemplarily, the harmonic current frequency output by the harmonic power supply 3 can be 250HZ, which is not specifically limited in this embodiment.

[0046] It can be understood that the freewheeling diode connected in parallel with the IGBT provides a freewheeling channel for the current when the IGBT is turned off, thereby avoiding voltage shock in the circuit and protecting the IGBT from damage.

[0047] It should be noted that by controlling the harmonic power supply 3 to adjust the magnitude of the output current, the current flowing through the ice-covered line 5 can reach the critical ice-melting current. If the critical ice-melting current cannot meet the specific rapid ice-melting occasion, the harmonic current output by the harmonic power supply 3 can be dynamically adjusted according to the required ice-melting current value, so that the current flowing through the ice-covered line 5 reaches the critical ice-melting current. If rapid ice-melting is required, the output current of the harmonic power supply 3 can be appropriately increased to remove the ice on the wire within the specified time. When it is observed that the ice layer of the ice-covered line 5 is loosened, melted and detached, the ice-melting system stops running and disconnects from the power grid.

[0048] In this embodiment, three-phase electricity of the second non-icing line is introduced through the first input terminal, the second input terminal and the third input terminal of the harmonic power supply to provide stable electric energy for the harmonic power supply, and the input voltage is adjusted by using the harmonic power supply to synthesize a voltage waveform with the amplitude and frequency required for ice melting, and then the harmonic current is input into the ice-covered line through the first output terminal, the second output terminal and the third output terminal of the harmonic power supply. The size of the ice-melting current can be dynamically adjusted according to actual conditions to achieve ice melting, thereby improving the flexibility of the ice-melting system.

[0049] Based on the above embodiments, Figure 3 is a partial structural diagram of another online ice melting system provided by an embodiment of the present invention. Figure 3 The structure of the first active filter is described below. Figure 1 and Figure 3As shown, the first active filter 1 includes a first transformer 11 and a first inverter 12, wherein the first transformer 11 includes a first primary winding 111 and a first secondary winding 112; the first primary winding 111 is connected in series in the first non-icing line 4; the first end of the first secondary winding 112 is connected to the first output end i of the first inverter 12, and the second end of the first secondary winding 112 is connected to the second output end j of the first inverter 12.

[0050] Specifically, the first active filter 1 can be a series active filter based on the fundamental magnetic flux compensation of the first non-icing line 4. When the ice is melted, the first active filter 1 connected in series with the first non-icing line 4 can be equivalent to an adjustable high harmonic impedance, wherein the first active filter 1 includes a first transformer 11 and a first inverter 12. The input end of the first inverter 12 is a DC power supply, and the DC power supply inputs DC power to the input end of the first inverter 12. With the fundamental current of the first non-icing line 4 as a reference, the input DC power is converted into a compensation current with the same frequency and opposite direction as the fundamental current of the first non-icing line 4 through a specific control strategy, and the compensation current is output to the first secondary winding 112 through the first output end i and the second output end j, thereby generating an equivalent impedance on the first primary winding 111 of the first transformer 11, so that the fundamental main magnetic flux compensation in the first primary winding 111 is zero. Therefore, the equivalent impedance corresponding to the first active filter 1 is low impedance to the fundamental current of the first non-icing line 4, and high impedance to harmonics. By connecting the first primary winding 111 in series to the first non-icing line 4, the de-icing current in the first non-icing line 4 is attenuated, forcing the harmonic current used for de-icing to flow into the de-icing circuit, so that the harmonic current flows in the de-icing circuit, thereby achieving online de-icing.

[0051] In this embodiment, the first inverter is used to control the equivalent impedance of the first active filter connected in series in the first non-iced line, so as to attenuate the harmonic current in the first non-iced line. When the harmonic current flows in the ice-melting circuit to melt the ice-covered line, it is ensured that the original three-phase circuit of the first non-iced line is not affected by the ice-melting current, thereby realizing online ice-melting of the ice-covered line and improving the reliability of power supply of the power grid during ice-melting.

[0052] Optional, continue to refer to Figure 1 and Figure 3 The first active filter 1 further includes a first filter inductor 13 ; a first end of the first filter inductor 13 is connected to a second end of the first secondary winding 112 , and a second end of the first filter inductor 13 is connected to a second output end j of the first inverter 12 .

[0053] Specifically, the first filter reactor 13 is provided between the first secondary winding 112 and the first inverter 12, which can effectively suppress the high-frequency switching noise generated by the first inverter 12, and prevent the noise from being transmitted to the first non-icing line 4 through the first transformer 11, thereby reducing electromagnetic interference to other devices, reducing damage to the electronic components of the first active filter 1 itself, and extending its service life. Connecting the first end of the first filter reactor 13 to the second end of the first secondary winding 112, and connecting the second end to the second output end j of the first inverter 12, helps to smooth the current waveform output by the first inverter 12 to the first secondary winding 112, reduce ripples and peaks in the current, thereby improving the quality of electric energy, helping to improve the power factor of the entire online ice melting system, and making the use of electric energy more efficient. At the same time, the first filter reactor 13 enables the first inverter 12 to more accurately control the compensation current injected into the first secondary winding 112, thereby improving the attenuation accuracy of the first active filter 1 to the harmonic current in the first non-icing line 4.

[0054] Optional, continue to refer to Figure 1 and Figure 3 The online ice melting system further includes a first control module 7 ; the first control module 7 is connected to the control end of the first inverter 12 .

[0055] Specifically, during ice melting, the first control module 7 obtains the current waveform in the first non-iced line 4, and uses mathematical tools such as Fourier transform to perform spectrum analysis on the current signal of the first non-iced line 4, identify the fundamental and harmonic components therein, and extract the magnitude and phase information of the current to be compensated according to the result of the spectrum analysis, and calculate the magnitude of the compensation current to be injected into the first secondary winding 112, so as to accurately control the compensation current output by the first inverter 12 through proportional integral differential (PID) control, sliding mode control or fuzzy control, and generate corresponding equivalent impedance in the first active filter 1 to attenuate the ice melting current in the first non-iced line 4.

[0056] Optional, continue to refer to Figure 1 and Figure 3 The online ice melting system also includes a first detection module 8 ; an input end of the first detection module 8 is connected to the three phases of the first non-icing line 4 , and an output end is connected to the first control module 7 .

[0057] Specifically, the first detection module 8 can be a current sensor, whose input end is connected to the three phases of the first non-icing line 4, and works based on the electromagnetic induction principle or the Hall effect principle, converting the current signal into a processable electrical signal, and can measure the current of the three-phase circuit of the first non-icing line 4 in real time. The detection module can also include a signal conditioning circuit, which amplifies, filters and performs analog-to-digital conversion on the collected electrical signal, and outputs the processed digital signal to the first control module 7 through the output end connected to the first control module 7. The first control module 7 receives the three-phase current data from the first detection module 8, and further processes and analyzes these data to generate the control instructions for the required compensation current, thereby adjusting the compensation current output by the first inverter 12, and attenuating the ice-melting current in the first non-icing line 4, ensuring the real-time and accuracy of the ice-melting current attenuation.

[0058] Based on the above embodiments, Figure 4 is a partial structural diagram of another online ice melting system provided by an embodiment of the present invention. Figure 4 The structure of the second active filter is described below. Figure 1 and Figure 4 As shown, the second active filter 2 includes a second transformer 21 and a second inverter 22, wherein the second transformer 21 includes a second primary winding 211 and a second secondary winding 212; the second primary winding 211 is connected in series in the second non-icing line 6; the first end of the second secondary winding 212 is connected to the first output end k of the second inverter 22, and the second end of the second secondary winding 212 is connected to the second output end m of the second inverter 22.

[0059] Specifically, the second active filter 2 can be a series active filter based on the fundamental magnetic flux compensation of the second non-ice-covered line 6. When melting ice, the second active filter 2 connected in series with the second non-ice-covered line 6 can be equivalent to an adjustable high harmonic impedance, wherein the second active filter 2 includes a second transformer 21 and a second inverter 22. The input end of the second inverter 22 is a DC power supply, and the DC power supply inputs DC power to the input end of the second inverter 22. With the fundamental current of the second non-ice-covered line 6 as a reference, the input DC power is converted into a compensation current with the same frequency and opposite direction as the fundamental current of the second non-ice-covered line 6 through a specific control strategy, and the compensation current is output to the second secondary winding 212 through the first output end k and the second output end m, thereby generating an equivalent impedance on the second primary winding 211 of the second transformer 21, so that the fundamental main magnetic flux compensation in the second primary winding 211 is zero. Therefore, the equivalent impedance corresponding to the second active filter 2 is low impedance to the fundamental current of the second non-ice-covered line 6, and high impedance to harmonics. By connecting the second primary winding 211 in series to the second non-icing line 6, the de-icing current in the second non-icing line 6 is attenuated, forcing the harmonic current used for de-icing to flow into the de-icing circuit, so that the harmonic current flows in the de-icing circuit, thereby achieving online de-icing.

[0060] In this embodiment, the equivalent impedance of the second active filter connected in series in the second non-iced line is adjusted by the second inverter to achieve attenuation of the harmonic current in the second non-iced line, so that the harmonic current flows in the ice-melting circuit to melt the ice-covered line, while ensuring that the original three-phase circuit of the second non-iced line is not affected by the ice-melting current, thereby achieving online ice-melting of the ice-covered line and improving the reliability of power supply of the power grid during ice-melting.

[0061] Optional, continue to refer to Figure 1 and Figure 4 The second active filter 2 further includes a second filter inductor 23 ; a first end of the second filter inductor 23 is connected to a second end of the second secondary winding 212 , and a second end of the second filter inductor 23 is connected to a second output end m of the second inverter 22 .

[0062] Specifically, a second filter reactor 23 is provided between the second secondary winding 212 and the second inverter 22, which can effectively suppress the high-frequency switching noise generated by the second inverter 22, and prevent the noise from being transmitted to the second non-ice-covered line 6 through the second transformer 21, thereby reducing electromagnetic interference to other devices, reducing damage to the electronic components of the second active filter 2 itself, and extending its service life. Connecting the first end of the second filter reactor 23 to the second end of the second secondary winding 212, and connecting the second end to the second output terminal m of the second inverter 22, helps to smooth the current waveform output by the second inverter 22 to the second secondary winding 212, reduce ripples and peaks in the current, thereby improving the quality of electric energy, helping to improve the power factor of the entire online ice melting system, and making the use of electric energy more efficient. At the same time, the second filter reactor 23 enables the second inverter 22 to more accurately control the compensation current injected into the second secondary winding 212, thereby improving the attenuation accuracy of the second active filter 2 on the harmonic current in the second non-ice-covered line 6.

[0063] Optional, continue to refer to Figure 1 and Figure 4 The online ice melting system further includes a second control module 9 ; the second control module 9 is connected to the control end of the second inverter 22 .

[0064] Specifically, during ice melting, the second control module 9 obtains the current waveform in the second non-iced line 6, and uses mathematical tools such as Fourier transform to perform spectrum analysis on the current signal of the obtained second non-iced line 6, identify the fundamental and harmonic components therein, and extract the magnitude and phase information of the current to be compensated according to the result of the spectrum analysis, and calculate the magnitude of the compensation current to be injected into the second secondary winding 212, so as to accurately control the compensation current output by the second inverter 22 through proportional integral differential (PID) control, sliding mode control or fuzzy control, and generate corresponding equivalent impedance in the second active filter 2 to attenuate the ice melting current in the second non-iced line 6.

[0065] Optional, continue to refer to Figure 1 and Figure 4 The online ice melting system further includes a second detection module 10 ; an input end of the second detection module 10 is connected to the three phases of the second non-icing line 6 , and an output end is connected to the second control module 9 .

[0066] Specifically, the second detection module 10 can be a current sensor, whose input end is connected to the three phases of the second non-icing line 6, and works based on the electromagnetic induction principle or the Hall effect principle, converting the current signal into a processable electrical signal, and can measure the current of the three-phase circuit of the second non-icing line 6 in real time. The detection module can also include a signal conditioning circuit, which amplifies, filters and performs analog-to-digital conversion on the collected electrical signal, and outputs the processed digital signal to the second control module 9 through the output end connected to the second control module 9. The second control module 9 receives the three-phase current data from the second detection module 10, and further processes and analyzes these data to generate the control instructions for the required compensation current, thereby adjusting the compensation current output by the second inverter 22, and attenuating the ice melting current in the second non-icing line 6, ensuring the real-time and accuracy of the ice melting current attenuation.

[0067] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An online ice melting system, characterized in that: It includes a first active filter, a second active filter and a harmonic power supply; The first active filter is connected in series to a first non-icing circuit, and the first non-icing circuit is connected to the head end of the ice-covered circuit; the second active filter is connected in series to a second non-icing circuit, and the second non-icing circuit is connected to the end of the ice-covered circuit; The first end of the harmonic power supply is connected to the head end of the ice-covered line, and the second end of the harmonic power supply is connected to the second non-ice-covered line; The harmonic power supply and the ice-covered line form an ice-melting circuit, wherein the harmonic power supply is used to generate an ice-melting current, the first active filter is used to attenuate the ice-melting current of the first non-ice-covered line, and the second active filter is used to attenuate the ice-melting current of the second non-ice-covered line.

2. The online ice melting system according to claim 1, characterized in that: The first end of the harmonic power supply includes a first output end, a second output end and a third output end, and the first output end, the second output end and the third output end are respectively connected to the three phases of the head end of the ice-covering line; The second end of the harmonic power supply includes a first input end, a second input end and a third input end, and the first input end, the second input end and the third input end are respectively connected to the three phases of the second non-icing line.

3. The online ice melting system according to claim 1, characterized in that: The first active filter comprises a first transformer and a first inverter, wherein the first transformer comprises a first primary winding and a first secondary winding; The first primary winding is connected in series in the first non-icing circuit; A first end of the first secondary winding is connected to a first output end of the first inverter, and a second end of the first secondary winding is connected to a second output end of the first inverter.

4. The online ice melting system according to claim 3, characterized in that: The first active filter further comprises a first filter reactor; The first end of the first filter reactor is connected to the second end of the first secondary winding, and the second end of the first filter reactor is connected to the second output end of the first inverter.

5. The online ice melting system according to claim 3, characterized in that: The online ice melting system also includes a first control module; The first control module is connected to the control end of the first inverter.

6. The online ice melting system according to claim 5, characterized in that: The online ice melting system also includes a first detection module; The input end of the first detection module is connected to the three phases of the first non-icing circuit, and the output end is connected to the first control module.

7. The online ice melting system according to claim 1, characterized in that: The second active filter comprises a second transformer and a second inverter, wherein the second transformer comprises a second primary winding and a second secondary winding; The second primary winding is connected in series in the second non-icing circuit; A first end of the second secondary winding is connected to a first output end of the second inverter, and a second end of the second secondary winding is connected to a second output end of the second inverter.

8. The online ice melting system according to claim 7, characterized in that: The second active filter further comprises a second filter reactor; The first end of the second filter reactor is connected to the second end of the second secondary winding, and the second end of the second filter reactor is connected to the second output end of the second inverter.

9. The online ice melting system according to claim 7, characterized in that: The online ice melting system also includes a second control module; The second control module is connected to the control end of the second inverter.

10. The online ice melting system according to claim 9, characterized in that: The online ice melting system also includes a second detection module; The input end of the second detection module is connected to the three phases of the second non-icing circuit, and the output end is connected to the second control module.

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