Direct-current deicing device and control method thereof

Abstract

The invention relates to the technical field of power line protection, and discloses a direct-current ice melting device and a control method thereof.According to the direct-current ice melting device, an alternating-current bus of an original alternating-current ice melting module is connected into the direct-current ice melting module through an isolation grounding switch, and the control relation between the alternating-current ice melting module and the direct-current ice melting module is optimized; the alternating current ice melting module and the direct current ice melting module are controlled in a coordinated mode through the control module, on the premise that reliable and effective control is guaranteed, control hierarchy arrangement is reduced, a control link is made to be simple and efficient, control time delay is reduced, protection action time when a system breaks down is shortened, free and automatic switching of the two ice melting modules can be achieved, and the system reliability is improved. And the ice melting efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power line protection, and in particular to a direct current ice melting device and a control method thereof. Background Art

[0002] Icing is common in cold climates, especially in winter. It can cause a large amount of ice to accumulate on transmission lines, thereby increasing the mechanical load on the lines and possibly leading to serious accidents such as line breakage and tower collapse, affecting the safe operation of the power system.

[0003] Traditional deicing methods include manual deicing, mechanical deicing, thermal deicing (such as heating by combustion), AC short circuit deicing, etc. These methods have problems such as low efficiency, high cost and poor safety.

[0004] At present, de-icing is carried out by using de-icing devices, which are specially designed to prevent or eliminate the problem of icing on transmission lines in power systems. The current de-icing devices are easily restricted by the operation mode of the power grid, and it is difficult to achieve automatic switching, which easily leads to low de-icing efficiency and threatens the stable operation of the power grid. Summary of the invention

[0005] In view of this, the present invention provides a DC ice melting device and a control method thereof, which solves the technical problem that the current ice melting device is easily restricted by the operation mode of the power grid, is difficult to achieve automatic switching, easily leads to low ice melting efficiency, and threatens the stable operation of the power grid.

[0006] A first aspect of the present invention provides a DC ice melting device, comprising an AC ice melting module, the AC ice melting module being connected to an AC bus, a first isolating grounding switch, a second isolating grounding switch, a control module and a DC ice melting module;

[0007] The first isolating and grounding switch is arranged on the AC bus;

[0008] One end of the second isolating grounding switch is connected to the AC busbar through an AC line, and the other end of the second isolating grounding switch is connected to the DC ice melting module;

[0009] The DC ice melting module includes a six-pulse rectifier, a first DC side voltage transformer, a second DC side voltage transformer, a first DC side current transformer, a second DC side current transformer and a DC conversion isolating switch;

[0010] One side of the six-pulse rectifier is electrically connected to the second isolating grounding switch;

[0011] The first end of the other side of the six-pulse rectifier is connected to the first DC side voltage transformer, and is electrically connected to the DC conversion isolation switch through the first DC side current transformer, and the first DC side voltage transformer is grounded;

[0012] The second end of the other side of the six-pulse rectifier is connected to the second DC side voltage transformer, and is electrically connected to the DC conversion isolation switch through the second DC side current transformer, and the second DC side voltage transformer is grounded;

[0013] The DC conversion isolating switch is connected to the DC ice-melting line;

[0014] The control module is electrically connected to the first isolating grounding switch and the second isolating grounding switch respectively; the control module is used to control the first isolating grounding switch and the second isolating grounding switch to close or open according to a pre-input control instruction.

[0015] Preferably, the DC ice melting module further includes a lightning arrester, and the lightning arrester is connected in parallel with the six-pulse rectifier.

[0016] Preferably, the continuous operating voltage of the lightning arrester is defined by a preset safety factor, a preset overvoltage factor and a valve-side line voltage; and the operating protection voltage of the lightning arrester is defined by the continuous operating voltage of the lightning arrester.

[0017] Preferably, the six-pulse rectifier comprises six commutation single valves, every two of the commutation single valves are connected in series to form a commutation branch, and every two of the commutation branches are connected in parallel;

[0018] Wherein, the single commutation valve comprises at least five thyristors, and the at least five thyristors are connected in series in sequence.

[0019] Preferably, the thyristor comprises an electrically controlled thyristor, a thyristor control electronic module, a damping resistor, a damping capacitor and a heat sink;

[0020] The damping resistor and the damping capacitor are connected in series to form a voltage-equalizing loop;

[0021] The voltage balancing circuit is connected in parallel with the electrically controlled thyristor;

[0022] The thyristor control electronic module is connected in series with the heat sink and the electrically controlled thyristor to form a loop.

[0023] Preferably, the device also includes a heat dissipation fan; the heat dissipation fan is used to dissipate heat for the six-pulse rectifier; the output air volume of the heat dissipation fan is limited by the total heating power, air specific heat, air density and the temperature difference between the inlet and outlet of the air duct.

[0024] Preferably, a voltage measurement module is provided on both the AC side and the DC side of the DC ice melting module;

[0025] The voltage measurement module is used to measure the voltage signals on the AC side and the DC side of the DC ice melting module;

[0026] The voltage measurement module is electrically connected to the control module, and the control module is used to perform overvoltage protection on the DC ice melting module according to the voltage signal.

[0027] Preferably, both the AC side and the DC side of the DC ice melting module are provided with current measurement modules;

[0028] The current measurement module is used to measure the current signals on the AC side and the DC side of the DC ice melting module;

[0029] The current measurement module is electrically connected to the control module, and the control module is used to perform undercurrent protection on the DC ice melting module according to the current signal.

[0030] Preferably, the DC ice melting module further comprises a valve control monitoring module, which is electrically connected to the six-pulse rectifier and the control module respectively, and is used to monitor the interface signal of each commutation valve in the six-pulse rectifier, and send the interface signal to the control module;

[0031] The control module is used to record the interface signal of each single converter valve, and identify the fault condition of each single converter valve according to the recording result of each single converter valve.

[0032] In a second aspect, the present invention further provides a control method for the DC ice melting device as described in the first aspect, comprising:

[0033] The control module controls the AC ice-melting module to melt the AC ice-melting line according to the AC ice-melting instruction input in advance;

[0034] When the control module receives a pre-input DC ice-melting instruction, it responds to the pre-input DC ice-melting instruction, controls the first isolating grounding switch and the second isolating grounding switch to close, and controls the DC ice-melting module to melt the DC ice-melting line.

[0035] It can be seen from the above technical solutions that the present invention connects the DC ice-melting module to the AC bus of the original AC ice-melting module using an isolating grounding switch, optimizes the control relationship between the AC ice-melting module and the DC ice-melting module, and coordinates the control of the AC ice-melting module and the DC ice-melting module through the control module. Under the premise of ensuring reliable and effective control, the control level setting is reduced, the control link is made simple and efficient, the control delay is reduced, the protection action time during system failure is shortened, and the two ice-melting modules can be switched freely and automatically, thereby improving the ice-melting efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative labor.

[0037] Figure 1 A schematic structural diagram of a DC ice melting device provided in an embodiment of the present invention;

[0038] Figure 2 A circuit schematic diagram of a DC ice melting device provided by an embodiment of the present invention;

[0039] Figure 3 A schematic diagram of the structure of a six-pulse rectifier provided in an embodiment of the present invention;

[0040] Figure 4 A schematic diagram of the structure of a single flow-converting valve provided in an embodiment of the present invention;

[0041] Figure 5 The present invention provides a flow chart of a control method of a DC ice melting device. DETAILED DESCRIPTION

[0042] 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 are within the scope of protection of the present invention.

[0043] like Figure 1~Figure 2 As shown, the embodiment of the present application provides a DC ice melting device, including an AC ice melting module 10, wherein the AC ice melting module 10 is connected to an AC bus, a first isolating grounding switch QS1, a second isolating grounding switch QS2, a control module 20 and a DC ice melting module 30;

[0044] The first isolating grounding switch QS1 is arranged on the AC bus;

[0045] One end of the second isolating grounding switch QS2 is connected to the AC busbar through an AC line, and the other end of the second isolating grounding switch QS2 is connected to the DC ice melting module 30;

[0046] Among them, the AC bus is a three-phase AC bus, and the first isolating grounding switch QS1 is connected to the three-phase AC bus, and is connected to the DC ice melting module 30 through another path through the second isolating grounding switch QS2. Among them, the DC ice melting module 30 can be an immersed ice melting device, and the DC ice melting switching switch is realized through the first isolating grounding switch QS1 and the second isolating grounding switch QS2 to realize switching between the DC ice melting line.

[0047] The DC ice melting module 30 includes a six-pulse rectifier, a first DC side voltage transformer TV1, a second DC side voltage transformer TV2, a first DC side current transformer TA1, a second DC side current transformer TA2 and a DC conversion isolating switch;

[0048] The DC ice melting module 30 uses a six-pulse rectifier and does not require a matching rectifier transformer. In the parameter setting, the rated DC voltage of the six-pulse rectifier is 12.5 kV, the rated DC current is 2000 A, and the 2h overload capacity is 1.2 pu.

[0049] One side of the six-pulse rectifier is electrically connected to the second isolating grounding switch QS2;

[0050] The first end of the other side of the six-pulse rectifier is connected to the first DC side voltage transformer TV1, and is electrically connected to the DC conversion isolation switch through the first DC side current transformer TA1, and the first DC side voltage transformer TV1 is grounded;

[0051] The second end of the other side of the six-pulse rectifier is connected to the second DC side voltage transformer TV2, and is electrically connected to the DC conversion isolation switch through the second DC side current transformer TA2, and the second DC side voltage transformer TV2 is grounded;

[0052] The DC conversion isolating switch is connected to the DC ice-melting line;

[0053] Among them, the DC conversion isolating switch adopts a total of 4 single-pole electric isolating switches QS11, QS12, QS21, and QS22 to realize the switching of the three-phase ice-melting line. The rectifier output DC is connected to the three-phase ice-melting busbar through the 4 single-pole electric isolating switches QS11, QS12, QS21, and QS22. The control module 20 controls the opening and closing of the 4 DC conversion isolating switches to realize the one-in-one-circuit or one-in-two-circuit mode of the ice-melting line.

[0054] Exemplarily, the single-pole electric isolating switches QS11 and QS22 are first controlled to be turned on to melt the ice on the AB phase lines. After the ice melting on the AB phase lines is completed, the control device controls the single-pole electric isolating switches QS11, QS12, and Q21 to be turned on, that is, short-circuiting the AB phases to melt the ice on the C phase.

[0055] The DC conversion isolating switch meets the requirements of DC working current, voltage and overload current in various working conditions. The DC conversion isolating switch adopts an electric operating mechanism, the knife switch is equipped with a local operating button and a manual operating device, and the operating mechanism has a "remote / local" conversion switch.

[0056] The control module 20 is electrically connected to the first isolating grounding switch QS1 and the second isolating grounding switch QS2 respectively; the control module 20 is used to control the first isolating grounding switch QS1 and the second isolating grounding switch QS2 to close or open according to a pre-input control instruction.

[0057] It is understandable that the control module 20 can control the first isolation grounding switch QS1 and the second isolation grounding switch QS2 to be closed or opened, so that the AC ice melting module 10 and the DC ice melting module 30 can work separately and independently, or the AC ice melting module 10 and the DC ice melting module 30 can work together to meet the ice melting demand and improve the ice melting efficiency.

[0058] It should be noted that the embodiment of the present application connects the DC ice-melting module to the AC bus of the original AC ice-melting module using an isolating grounding switch, optimizes the control relationship between the AC ice-melting module and the DC ice-melting module, and coordinates the control of the AC ice-melting module and the DC ice-melting module through the control module. Under the premise of ensuring reliable and effective control, the control level setting is reduced, the control link is made simple and efficient, the control delay is reduced, the protection action time during system failure is shortened, and the two ice-melting modules can be switched freely and automatically, thereby improving the ice-melting efficiency.

[0059] like Figure 2 As shown, the DC ice melting module further includes a lightning arrester F1, which is connected in parallel with the six-pulse rectifier.

[0060] In actual application, the arrester F1 is used to protect the entire DC de-icing device. All necessary arresters are provided. The arresters comply with the provisions of GB / T 22389-2008 (Guidelines for gapless zinc oxide arresters for high-voltage DC converter stations). In addition, the arrester of the DC de-icing device is used to limit the operating overvoltage, and a gapless metal oxide arrester can be selected.

[0061] The rated voltage of the lightning arrester is the upper limit of the normal operating voltage, with a certain margin.

[0062] In actual projects, by verifying the current carrying capacity of the arrester, a DC arrester is configured to limit the overvoltage shock that occurs in the ice melting device under extreme conditions, and to protect the ice melting device and DC output equipment. The selection of the continuous operating voltage of the arrester, the selection of the energy, and the selection of the protection voltage are the main parameters of the arrester design. First, the continuous operating voltage of the arrester is determined. The principle of selecting the continuous operating voltage of the arrester is to ensure that it is greater than the output voltage of the ice melting device under the most severe normal working conditions, and has a certain safety margin. Based on this, the continuous operating voltage of the arrester is limited by the preset safety factor, the preset overvoltage factor, and the valve side line voltage. That is, the continuous operating voltage of the arrester is:

[0063]

[0064] In the formula, is the continuous operating voltage of the arrester, is the safety factor, which can be taken as 1.2. is the overvoltage coefficient, which can be taken as 1.1. is the valve side line voltage.

[0065] According to the characteristics of DC lightning arresters, the operating protection voltage of the lightning arrester is limited by the continuous operating voltage of the lightning arrester. The operating protection voltage of the lightning arrester is 1.6 times the continuous operating voltage of the lightning arrester. Based on this, the operating protection voltage of the lightning arrester for:

[0066]

[0067] Exemplarily, based on the continuous operating voltage and operating protection voltage of the arrester and combined with the PSCAD simulation model, the technical parameters of the DC arrester are designed as follows: continuous operating voltage: 20kV; nominal discharge current: 18kA; operating impulse current: 2kA; operating protection voltage: 32kV; 2ms square wave current: 800A; absorbed energy: 200kJ.

[0068] In some embodiments, Figure 2 As shown, the six-pulse rectifier includes six commutation single valves V1~V6, every two commutation single valves are connected in series to form a commutation branch, and every two commutation branches are connected in parallel;

[0069] The single commutation valve includes at least five thyristors, and the at least five thyristors are connected in series in sequence.

[0070] It is understood that the minimum number of thyristors in series is determined by the non-repetitive forward voltage of the thyristor and the maximum voltage that the valve withstands. The number of thyristors in series is selected according to the operating impulse test voltage level that the valve withstands. The minimum number of thyristors in series is:

[0071]

[0072] Where U SIPL k is the arrester operation impulse protection level (the arrester protection level of this project is designed to be 32kV); s is the test safety factor; k L is the operating impact uneven pressure coefficient; Minimum number of thyristors required for a single valve without redundancy; V RRM is the reverse repetitive peak voltage of the thyristor stage.

[0073] For example, Figure 3 As shown, the number of thyristors is 7, namely thyristors 1, 2, 3, 4, 5, 6, and 7, of which 2 thyristors are redundant thyristors with a redundancy of 40%, thereby improving the reliability of commutation.

[0074] Among them, 5-inch thyristors can be used, and there is no need to use thyristors in parallel, which improves the reliability of the system.

[0075] like Figure 4 As shown, the thyristor includes an electronically controlled thyristor R1, a thyristor control electronic module TCE, a damping resistor R, a damping capacitor C1 and a heat sink TT;

[0076] The damping resistor R and the damping capacitor C1 are connected in series to form a voltage-equalizing circuit;

[0077] The voltage-equalizing circuit is connected in parallel with the electronically controlled thyristor R1;

[0078] The thyristor control electronic module TCE is connected in series with the heat sink TT and the electronically controlled thyristor R1 to form a loop.

[0079] Among them, the purpose of the voltage equalization circuit is to protect the thyristor from damage by transient overvoltage and to achieve uniform voltage distribution in the valve under various possible voltage conditions.

[0080] The voltage distribution between thyristors is uniform, power is provided to the thyristor control electronic module, the commutation overshoot is limited when the thyristor valve is turned off, and the voltage distribution inside the thyristor valve is uniform.

[0081] When selecting the damping capacitor, the loss of the commutation valve should be minimized while absorbing the thyristor valve commutation overvoltage. The commutation overshoot in the valve is caused by the shutoff of other valves in a 6-pulse valve. The selected capacitor must ensure that it can damp the commutation overshoot.

[0082] The calculation formula of damping resistance is as follows:

[0083]

[0084] In the formula, is the commutation inductance; is the proportionality coefficient; is the number of thyristors in each valve; is the damping capacitor.

[0085] The main function of the thyristor control electronic module is to trigger and monitor the thyristor. The thyristor control electronic module also has a protection trigger circuit and a reverse recovery protection trigger circuit. The components of the thyristor control electronic module are located on a 7.2×20 cm circuit board. The main functions are: triggering the thyristor, monitoring the thyristor status, including the status of the protection trigger, reverse recovery period protection, and power supply monitoring.

[0086] The power supply of the thyristor control electronics is taken from the voltage across the thyristor, ensuring reliable triggering of the thyristor under all operating conditions and surge voltages. As long as voltage is present, the valve can operate without restriction and without any delay.

[0087] All control and protection functions of the thyristor controlled electronic module are performed by electronic components, i.e. on the printed circuit board, without high voltage components.

[0088] In the DC test, the voltage distribution of the series thyristor is mainly determined by the voltage divider resistance between the positive and negative electrodes. Due to the geometric size error of the liquid cooling loop pipeline, there is bound to be an error in the loop resistance, which will lead to uneven voltage distribution. The resulting average voltage deviation is less than 5% of the voltage of each thyristor.

[0089] Therefore, in the extreme case, the average voltage across the thyristor is:

[0090]

[0091]

[0092] Where k is the voltage distribution imbalance coefficient caused by component error, which is 1.05; V TDC is the valve DC test voltage; n T.min To ignore the number of redundant thyristors: the value is 5; V DC The rated DC voltage of the six-pulse bridge is 12.5 kV. DC The safety factor for a 1-minute test is 1.6.

[0093] The maximum AC voltage of the thyristor stage is:

[0094]

[0095] Where V TH.AC V is the AC voltage that the thyristor withstands; AC is the valve AC test voltage.

[0096] Reverse voltage of thyristor:

[0097] Thyristor forward voltage:

[0098] Where U v0.max k is the maximum line voltage of the valve side winding in no-load steady state; r is the transient overvoltage coefficient, generally k r The value is 1.3; k c is the commutation overshoot coefficient, generally k c The value is 1.1; k s is the test safety factor, generally k s The value is 1.15;

[0099] The maximum AC voltage of the thyristor stage is:

[0100]

[0101] V TH.ACF Lower than the V of the thyristor RRM (8500V).

[0102] The converter valve has the ability to bear the rated current, overload current and various transient impact currents. Since the rated current of a single 5-inch thyristor is 3200A, it can fully meet the rated current requirements.

[0103] The selected thyristor has a rated current of 3200A, and the maximum current when the thyristor is turned on is 1154A. Its current margin is 4.3 times, and the calculation results are as follows:

[0104]

[0105] The commutation valve can withstand the following faults: ground fault on the AC side and DC side, valve short circuit, AC system fault. The valve is designed to lock in the event of the most severe transient current impact. It can withstand 3 cycles of current without subsequent locking.

[0106] The thyristor surge current selected for the single converter valve is 38.5kA, which fully meets the tolerance requirements of the short-circuit current (<10 times the rated current) at the DC side outlet of the ice melting device, and can ensure the reliable operation of the converter valve.

[0107] In some embodiments, the DC ice melting device provided in the embodiments of the present application also includes a heat dissipation fan; the heat dissipation fan is used to dissipate heat from the six-pulse rectifier; the output air volume of the heat dissipation fan is limited by the total heating power, air specific heat, air density and the temperature difference between the inlet and outlet of the air duct.

[0108] Among them, the air volume is calculated according to the heat balance, and the heat dissipation fan is used to take away the heat generated during the operation of the thyristor valve and dissipate it to the outdoor air. The air volume Q required by the heat dissipation fan can be calculated according to the heat balance equation:

[0109]

[0110] Where, P is the total heating power of the components in the air duct; is the specific heat of air, generally The value is 1.005×10 3 J / kg·K; is the air density, generally The value is 1.165kg / m 3 ; △T is the temperature difference between the inlet and outlet of the air duct. The △T value considered in this project is 10K.

[0111] For example, according to the above power consumption (120kW), substituting into the above formula, we can get:

[0112] (m 3 / h)

[0113] Considering the safety margin of 1.5 times, the air volume of the heat dissipation fan of the DC ice melting device provided in the embodiment of the present application should be greater than 50000m 3 / h. Two 10000m3 / s are installed under each phase rectifier immersion box corresponding to the DC ice melting module. 3 / h fan, 6 three-phase 10000m 3 / h fan.

[0114] In some embodiments, a voltage measurement module is provided on both the AC side and the DC side of the DC ice melting module;

[0115] The voltage measurement module is used to measure the voltage signals on the AC side and the DC side of the DC ice melting module;

[0116] The voltage measurement module is electrically connected to the control module, and the control module is used to perform overvoltage protection on the DC ice melting module according to the voltage signal.

[0117] Among them, the voltage measurement module adopts a resistor-capacitor voltage divider, which has high linearity, fast response, good transient response and frequency response characteristics, and meets the measurement accuracy requirements of the DC ice melting device control and protection system.

[0118] In some embodiments, both the AC side and the DC side of the DC ice melting module are provided with current measurement modules;

[0119] The current measurement module is used to measure the current signals on the AC side and the DC side of the DC ice melting module;

[0120] The current measurement module is electrically connected to the control module, and the control module is used to perform undercurrent protection on the DC ice melting module according to the current signal.

[0121] Among them, the current measurement module uses a Hall current sensor, which has good transient response and frequency response characteristics, and meets the measurement accuracy requirements of the DC ice melting device control and protection system.

[0122] In some embodiments, the DC ice melting module further includes a valve control monitoring module, which is electrically connected to the six-pulse rectifier and the control module, respectively, and is used to monitor the interface signal of each commutation valve in the six-pulse rectifier, and send the interface signal to the control module;

[0123] The control module is used to record the interface signal of each single converter valve and identify the fault condition of each single converter valve according to the recording result of each single converter valve.

[0124] In some embodiments, the recording conditions of the interface signals of each single converter valve can determine the amplitude and phase of the interface signals of each single converter valve, and perform threshold comparison based on the amplitude and phase of the interface signals of each single converter valve to determine whether there are fault conditions such as sudden changes in the amplitude and phase of the interface signals of each single converter valve, to determine whether there are faults in each single converter valve, and all thyristor-level feedback signals have been covered, which is convenient for system analysis and rapid fault location.

[0125] Based on the same inventive concept, an embodiment of the present application further provides a control method for implementing the DC ice melting device involved above.

[0126] The implementation scheme for solving the problem provided by the control method is similar to the implementation scheme recorded in the above method, so the specific limitations in the control method embodiments of one or more DC ice melting devices provided below can refer to the limitations on DC ice melting devices above, which will not be repeated here.

[0127] like Figure 5 As shown, the embodiment of the present application provides a control method for the DC ice melting device in the above embodiment, including:

[0128] Step S1, controlling the AC ice-melting module to melt the AC ice-melting line according to the AC ice-melting instruction input in advance by the control module;

[0129] Step S2: When the control module receives the pre-input DC ice-melting instruction, it responds to the pre-input DC ice-melting instruction and controls the first isolating grounding switch and the second isolating grounding switch to close, and controls the DC ice-melting module to melt the DC ice-melting line.

[0130] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the method described above can refer to the corresponding process in the aforementioned device embodiment, and will not be repeated here.

[0131] 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.

[0132] In several embodiments provided by the present invention, it is understood that each box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and a part of a module, a program segment or a code includes one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved.

[0133] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0134] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A DC ice melting device, comprising an AC ice melting module, wherein the AC ice melting module is connected to an AC bus, and is characterized in that: A first isolating grounding switch, a second isolating grounding switch, a control module and a DC ice melting module; The first isolating and grounding switch is arranged on the AC bus; One end of the second isolating grounding switch is connected to the AC busbar through an AC line, and the other end of the second isolating grounding switch is connected to the DC ice melting module; The DC ice melting module includes a six-pulse rectifier, a first DC side voltage transformer, a second DC side voltage transformer, a first DC side current transformer, a second DC side current transformer and a DC conversion isolating switch; One side of the six-pulse rectifier is electrically connected to the second isolating grounding switch; The first end of the other side of the six-pulse rectifier is connected to the first DC side voltage transformer, and is electrically connected to the DC conversion isolation switch through the first DC side current transformer, and the first DC side voltage transformer is grounded; The second end of the other side of the six-pulse rectifier is connected to the second DC side voltage transformer, and is electrically connected to the DC conversion isolation switch through the second DC side current transformer, and the second DC side voltage transformer is grounded; The DC conversion isolating switch is connected to the DC ice-melting line; The control module is electrically connected to the first isolating and grounding switch and the second isolating and grounding switch respectively; The control module is used to control the first isolating grounding switch and the second isolating grounding switch to be closed or opened according to a pre-input control instruction.

2. The DC ice melting device according to claim 1, characterized in that: The DC ice melting module further includes a lightning arrester, which is connected in parallel with the six-pulse rectifier.

3. The DC ice melting device according to claim 2, characterized in that: The continuous operating voltage of the lightning arrester is defined by a preset safety factor, a preset overvoltage factor and a valve-side line voltage; the operating protection voltage of the lightning arrester is defined by the continuous operating voltage of the lightning arrester.

4. The DC ice melting device according to claim 1, characterized in that: The six-pulse rectifier includes six commutation single valves, every two of the commutation single valves are connected in series to form a commutation branch, and every two of the commutation branches are connected in parallel; Wherein, the single commutation valve comprises at least five thyristors, and the at least five thyristors are connected in series in sequence.

5. The DC ice melting device according to claim 4, characterized in that: The thyristor comprises an electrically controlled thyristor, a thyristor control electronic module, a damping resistor, a damping capacitor and a heat sink; The damping resistor and the damping capacitor are connected in series to form a voltage-equalizing loop; The voltage balancing circuit is connected in parallel with the electrically controlled thyristor; The thyristor control electronic module is connected in series with the heat sink and the electrically controlled thyristor to form a loop.

6. The DC ice melting device according to claim 1, characterized in that: It also includes a heat dissipation fan; the heat dissipation fan is used to dissipate heat for the six-pulse rectifier; the output air volume of the heat dissipation fan is limited by the total heating power, air specific heat, air density and the temperature difference between the inlet and outlet of the air duct.

7. The DC ice melting device according to claim 1, characterized in that: The AC side and the DC side of the DC ice melting module are both provided with voltage measurement modules; The voltage measurement module is used to measure the voltage signals on the AC side and the DC side of the DC ice melting module; The voltage measurement module is electrically connected to the control module, and the control module is used to perform overvoltage protection on the DC ice melting module according to the voltage signal.

8. The DC ice melting device according to claim 1, characterized in that: The AC side and the DC side of the DC ice melting module are both provided with current measurement modules; The current measurement module is used to measure the current signals on the AC side and the DC side of the DC ice melting module; The current measurement module is electrically connected to the control module, and the control module is used to perform undercurrent protection on the DC ice melting module according to the current signal.

9. The DC ice melting device according to claim 1, characterized in that: The DC ice melting module further includes a valve control monitoring module, which is electrically connected to the six-pulse rectifier and the control module respectively, and is used to monitor the interface signal of each commutation valve in the six-pulse rectifier and send the interface signal to the control module; The control module is used to record the interface signal of each single converter valve, and identify the fault condition of each single converter valve according to the recording result of each single converter valve.

10. A control method for a DC ice melting device according to any one of claims 1 to 9, characterized in that: include: The control module controls the AC ice-melting module to melt the AC ice-melting line according to the AC ice-melting instruction input in advance; When the control module receives a pre-input DC ice-melting instruction, it responds to the pre-input DC ice-melting instruction, controls the first isolating grounding switch and the second isolating grounding switch to close, and controls the DC ice-melting module to melt the DC ice-melting line.

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