Alternating-current uninterrupted ice melting device for medium-voltage power transmission line

Abstract

The utility model relates to an alternating-current uninterrupted ice melting device for a medium-voltage power transmission line, which comprises a plurality of groups of ice melting equipment used for being put into the power transmission line at different times, and the maximum value of transient inrush current generated when a single group of ice melting equipment is put into use is smaller than a protection current setting value of the power transmission line; the ice melting equipment comprises a head end part connected in parallel to a power transmission side and a tail end part connected in parallel to a load side; the head-end single-group parallel capacitor part comprises a capacitor for generating capacitive reactive current and inrush current, a switch, a resistor and a current-limiting reactor, and the capacitor part is connected with the power transmission side in parallel. And the tail-end single-group shunt reactor part consists of a switch, a resistor and a reactor, and is connected in parallel with the load side. According to the invention, multiple groups of ice melting equipment are arranged, and the maximum value of the generated transient inrush current is limited within the protection current setting value during sequential input, so that the protection operation of a normal line is not caused and the line is not mistakenly tripped while online ice melting is met.

Description

Technical Field

[0001] The utility model relates to the field of on-line ice melting, in particular to an AC power-off ice melting device for medium-voltage transmission lines. Background Art

[0002] In winter, icing of 10kV and 35kV transmission lines is extremely common under some special environmental and climatic conditions. Therefore, it is necessary to melt the ice on the transmission lines in winter.

[0003] Existing ice melting methods are all power-off ice melting. Ice melting equipment is a one-time investment. The rated ice melting current and impact current are relatively large, which is likely to cause the protection operation of normal lines and result in mis-tripping of the lines. Summary of the Utility Model

[0004] In view of this, the purpose of the utility model is to provide an AC power-off ice melting device for medium-voltage transmission lines to solve the problem that the existing ice melting device is likely to cause the protection operation of normal lines and result in mis-tripping of the lines.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The AC power-off ice melting device for medium-voltage transmission lines of the utility model includes multiple groups of ice melting equipment for being put into the transmission line at different times. The maximum value of the transient inrush current generated when the single group of ice melting equipment is put into operation is less than the protection current setting value of the transmission line.

[0007] The ice melting equipment includes a first end part connected in parallel to the power transmission side and a second end part connected in parallel to the load side.

[0008] The first end part includes a capacitor, a switch, a resistor and a current-limiting reactor that generate a transient inrush current when closed. The capacitor part is connected in parallel to the power transmission side and generates a large capacitive reactive current at steady state.

[0009] The second end part includes a reactor, a switch and a resistor. The reactor part is connected in parallel to the load side and generates a large inductive reactive current at steady state.

[0010] In an embodiment of the present application, the first end part is connected to the transmission line through a switching switch, including a shunt capacitor, an internal discharge circuit after disconnection and a current-limiting reactor when the shunt capacitor is closed. The second end part is connected to the transmission line through a switching switch and has a reactor and an internal short-circuit circuit when disconnected.

[0011] In an embodiment of the present application, when the transmission line is a 10kV line, three groups are provided for each of the first end part and the second end part. The single-group capacity of the capacitor is 866kVA, and the reactance rate of the reactor is 8%.

[0012] In an embodiment of the present application, when the transmission line is a 35 kV line, four groups are provided for each of the head end part and the tail end part, the single-group capacity of the capacitor is 3031 kVA, and the reactance rate of the reactor is 8%.

[0013] In an embodiment of the present application, the switch is a remote switch.

[0014] The beneficial effects of the present utility model are as follows: The medium-voltage transmission line AC power-off-free ice melting device of the present utility model includes multiple groups of ice melting devices for inputting into the transmission line at different times. The maximum value of the transient inrush current generated when the ice melting device is input is less than the protection current setting value of the transmission line; the ice melting device includes a head end part connected in parallel on the power transmission side and a tail end part connected in parallel on the load side; the head end part includes a capacitor, a switch, a resistor, and a current-limiting reactor that generate a transient inrush current when closed. The capacitor part is connected in parallel with the power transmission side and generates a large capacitive reactive current in the steady state; the tail end part includes a reactor, a switch, and a resistor. The reactor part is connected in parallel with the load side and generates a large inductive reactive current in the steady state. In the present application, multiple groups of ice melting devices are provided. When they are input sequentially, the maximum value of the generated transient inrush current is limited within the protection current setting value. Therefore, while meeting the on-line ice melting requirement, it will not cause the protection operation of the normal line and cause mis-tripping of the line. Description of the Drawings

[0015] The present utility model will be further described below in conjunction with the drawings and embodiments:

[0016] Figure 1 It is a schematic structural diagram of the medium-voltage transmission line AC power-off-free ice melting device in the present application;

[0017] Figure 2 It is a schematic structural diagram of the ice melting device in the present application;

[0018] Figure 3 It is a diagram of the inrush current when the present application is put into operation;

[0019] Figure 4 It is a diagram of the inrush current when the ice melting device in a comparative example of the present application is put into operation;

[0020] Figure 5 It is a schematic diagram of the bus voltage change between the present application and the comparative example. Detailed Embodiments

[0021] The following describes the implementation modes of the present utility model through specific examples. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through other different specific implementation modes. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0022] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present utility model in a schematic manner. Therefore, only the layers related to the present utility model are shown in the diagrams, rather than being drawn according to the number, shape, and size of the layers during actual implementation. The type, quantity, and ratio of each layer during actual implementation can be arbitrarily changed, and the layer layout type may also be more complex.

[0023] In the following description, a large number of details are explored to provide a more thorough explanation of the embodiments of the present utility model. However, it is obvious to those skilled in the art that the embodiments of the present utility model can be implemented without these specific details.

[0024] As Figure 1 - Figure 2 shown, it includes multiple groups of ice melting devices for being put into the transmission line at different times. The maximum value of the transient inrush current generated when a single group of ice melting devices is put in is less than the setting value of the protection current of the transmission line;

[0025] The ice melting device includes a first end part connected in parallel on the power transmission side and a second end part connected in parallel on the load side;

[0026] As Figure 1 shown, this application sets 3 groups of ice melting devices. E S is the power transmission side, R LD is the load side, S 1 is the first end part of the first group of ice melting devices, E 1 is the second end part of the first group of ice melting devices; S 2 is the second end part of the second group of ice melting devices, E 2 is the second end part of the second group of ice melting devices; S 3 is the second end part of the third group of ice melting devices, E 3 is the second end part of the third group of ice melting devices.

[0027] The first end part includes a capacitor C for generating capacitive reactive current and inrush current, the overall capacitor device, a first switch CB connected in parallel with the transmission line 1 and a capacitor resistor R C a current-limiting reactor L 1 and the internal resistance rc of the current-limiting reactor, and other internal switches of the capacitor.

[0028] The end part includes a reactor L for generating inductive reactive current, a reactor overall device and a second switch CB connected in parallel on the load side of the transmission line. 4 and the internal resistance R of the shunt reactor L .

[0029] In one embodiment of the present application, the head end portion is connected through a switch CB 1 Connected to the transmission line, the end part passes through the switch CB 4 Connected to the transmission line. The head end is connected to the transmission line through a switch, including a shunt capacitor, an internal discharge circuit after disconnection, and a current limiting reactor when the shunt capacitor is closed. The tail end is connected to the transmission line through a switch, and has a reactor and an internal short-circuit circuit when disconnected. Switch CB1 and switch CB4 are remote control switches.

[0030] In one embodiment of the present application, when the transmission line is a 10kV line, three groups are respectively arranged at the head end and the tail end, the capacity of a single group of capacitors is 866kVA, and the reactance rate of the current limiting reactor of the capacitor is 8%. When the transmission line is a 35kV line, four groups are respectively arranged at the head end and the tail end, the capacity of a single group of capacitors is 3031kVA, and the reactance rate of the current limiting reactor of the capacitor is 8%.

[0031] Standardization of ice melting equipment for lines of different voltage levels and different transmission capacities can be quickly and typically designed, produced, transported, installed and operated. After standardization, it is easy to quickly master the installation methods, operating procedures and precautions, which is conducive to the use and operation of the staff, and is conducive to universal and comprehensive promotion, and is beneficial to the spare and maintenance of the equipment.

[0032] Ice on 10kV and 35kV transmission lines in winter is very likely to occur under some special environmental and climatic conditions. When configuring AC non-stop ice-melting devices, its cost-effectiveness needs to be considered. In order to save the cost of configuring equipment, ice-melting equipment is configured in fixed groups for important lines. If the ice-covered area is in a large area, it can be configured in a fixed and unified optimized manner. In order to save costs, a mobile AC non-stop ice-melting device can be configured in groups, and multiple ice-covered lines can share a set of AC non-stop ice-melting devices.

[0033] The capacity of the parallel capacitor group of the 10kV line de-icing device is 2600kVA, divided into 3 groups. The standard capacity of each group is 866kVA, and each group injects 50A of de-icing reactive current. When each group is put into operation, the inrush current is controlled at 5 times of 50A, that is, 250A (because the inrush time is short, it can avoid the I section protection of the line, and the de-icing device can be automatically switched), and the capacitor's current limiting reactor reactance rate is designed to be 8% (so that the weight, size and cost of the equipment can be very small). After all 3 groups are put into operation, the de-icing reactive current injected when the parallel capacitor overall equipment is stable is 150A, which can quickly de-ice the 10kV line.

[0034] The total capacity of the ice melting equipment for the 35kV line is 12124 kVA, divided into 4 groups, with each group having a standard capacity of 3031 kVA. The reactive ice melting current injected into each group is 50 A (the inrush current multiple is taken as 5 times, which can avoid the conventional protection of this line), and the reactance rate of the current limiting reactor for the capacitor bank is 8%. The total reactive ice melting current injected by the 4 groups is 250 A.

[0035] In an embodiment of the present application, switch CB 1 and switch CB 4 are remote switches and can be remotely switched on.

[0036] Figure 3 This is the inrush current diagram when the present application is put into operation. As Figure 3 shown, the present application can well control the inrush current within the protection setting value, ensuring that the corresponding protection withdrawal mechanism is not triggered.

[0037] Figure 4 This is the inrush current diagram of the ice melting device in a comparative example of the present application when it is put into operation. As Figure 4 shown, when the ice melting device without grouping is put into operation, it is easy for the maximum value of the inrush current to exceed the protection setting value, easily triggering the current protection action of the circuit. The capacity of the shunt capacitor bank of the 10kV line ice melting device is 2600 kVA, divided into 3 groups. The standard capacity of each group is 866 kVA, and the reactive ice melting current injected into each group is 50 A. The inrush current during the input of each group is controlled within 5 times of 50 A, that is, 250 A (because the inrush current time is short, it can avoid the I-section protection of this line, and the ice melting device can be automatically switched on and off). If not grouped, the capacitor that generates a capacitive reactive current of 150 A in the steady state will generate an inrush current of 450 A when put into operation, far exceeding the current protection setting value of the 10kV transmission line, resulting in the inability of the ice melting equipment to be automatically switched on. The total capacity of the ice melting equipment for the 35kV line is 12124 kVA, divided into 4 groups, with each group having a standard capacity of 3031 kVA. The reactive ice melting current injected into each group is 50 A (the inrush current multiple is taken as 5 times, which can avoid the conventional protection of this line), and the total reactive ice melting current injected by the 4 groups is 250 A. If not grouped, the capacitor that generates a capacitive reactive current of 250 A in the steady state will generate an inrush current of 750 A when put into operation, far exceeding the current protection setting value of the 35kV transmission line, resulting in the inability of the ice melting equipment to be automatically switched on.

[0038] In addition, by using grouped equipment in the present application, the voltage variation of the busbar can also be made smaller when the ice melting equipment is put into operation. Figure 5 This is the schematic diagram of the busbar voltage change between the present application and the comparative example. As Figure 5 shown, by adopting the grouped operation method, the busbar voltage change can be significantly reduced.

[0039] The AC live-line ice melting device for medium-voltage transmission lines of the present utility model includes multiple groups of ice melting devices for being put into the transmission lines at different times. The maximum value of the transient inrush current generated when the ice melting device is put into operation is less than the setting value of the protection current of the transmission line. The ice melting device includes a first end part connected in parallel to the power transmission side and a second end part connected in parallel to the load side. The first end part includes a capacitor C for generating capacitive reactive current and inrush current, a first switch CB1 for connecting the whole capacitor device in parallel with the transmission line, a capacitor resistor RC, a current-limiting reactor L1 and the internal resistance rc of the current-limiting reactor, and other internal switches of the capacitor. The second end part includes a reactor L for generating inductive reactive current, a second switch CB4 for connecting the whole reactor device in parallel with the load side of the transmission line, and the internal resistance RL of the shunt reactor. In this application, multiple groups of ice melting devices are provided. When they are put into operation in sequence, the maximum value of the transient inrush current generated is limited within the setting value of the protection current. Therefore, while meeting the requirement of live-line ice melting, it will not cause the protection operation of the normal line and result in mis-tripping of the line.

[0040] In the above embodiments, although the present utility model has been described in conjunction with specific embodiments of the present utility model, many substitutions, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art based on the foregoing description. The embodiments of the present utility model are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims.

[0041] The above embodiments are only illustrative of the principles and effects of the present utility model and are not intended to limit the present utility model. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present utility model. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present utility model should still be covered by the claims of the present utility model.

Claims

1. A medium voltage transmission line AC non-stop ice melting device, characterized in that: It includes a plurality of groups of ice-melting equipment for putting into use in the transmission line at different times, and the maximum value of the transient inrush current generated by the ice-melting equipment when it is put into use is less than the protection current setting value of the transmission line; The ice melting device includes a head end portion connected in parallel to the power transmission side and a terminal end portion connected in parallel to the load side; The head end part includes a capacitor, a switch, a resistor and a current limiting reactor that generate transient inrush current when combined. The capacitor is connected in parallel with the power transmission side and generates a large capacitive reactive current in a steady state. The terminal part includes a reactor, a switch and a resistor. The reactor part is connected in parallel with the load side and generates a large inductive reactive current in a steady state.

2. The AC non-stop ice melting device for medium voltage power transmission lines according to claim 1, characterized in that: The head end part is connected to the transmission line through a cut-in switch, and contains a parallel capacitor, an internal discharge circuit after disconnection, and a current limiting inductor when the parallel capacitor is closed. The tail end part is connected to the transmission line through a cut-in switch, and has an inductor and an internal short-circuit circuit when disconnected.

3. The AC non-stop ice melting device for medium voltage power transmission lines according to claim 1, characterized in that: When the transmission line is a 10 kV line, three groups are respectively provided at the head end portion and the tail end portion, the capacity of the capacitor is 866 kVA, and the reactance rate of the reactor is 8%.

4. The AC non-stop ice melting device for medium voltage power transmission lines according to claim 1, characterized in that: When the transmission line is a 35 kV line, four groups are provided at the head end portion and the tail end portion, the capacity of the capacitor is 3031 kVA, and the reactance rate of the reactor is 8%.

5. The AC non-stop ice melting device for medium voltage power transmission lines according to claim 1, characterized in that: The switch is a remote switch.

Images