Power transmission and distribution line ice melting characteristic simulation load system and operation method

Abstract

The invention discloses a power transmission and distribution line ice melting characteristic simulation load system and an operation method, and the system comprises a positive port and a negative port, the positive port is connected with the positive electrode of an ice melting device, the negative port is connected with the negative electrode of the ice melting device, the positive port is connected with a positive bus, and the negative port is connected with a negative bus. A plurality of impedance units are arranged between the positive bus and the negative bus; and the series-parallel connection combination state of the impedance units is adjusted according to the expected ice melting voltage input by the positive electrode port. According to the mode, large load current can be obtained in a wide input voltage range, load testing requirements of high-voltage large current and low-voltage large current are considered, and the problem that rated power of a conventional load is too large due to the fact that the high-voltage large current and the low-voltage large current are considered is solved.

Description

Technical Field

[0001] This invention relates to the field of electrical line de-icing technology, and in particular to a load simulation system and operating method for de-icing characteristics of power transmission and distribution lines. Background Technology

[0002] my country frequently experiences snow and ice disasters. Icing on power transmission and distribution lines often leads to line breaks, tower collapses, and other accidents, causing prolonged power outages and seriously threatening the safe operation of the power grid and the reliability of power supply. To reduce accidents caused by snow and ice disasters, existing technologies involve timely de-icing operations based on the icing situation. De-icing devices, as emergency equipment, are generally only used for short periods after severe icing of lines during winter rain and snow. To ensure the normal operation of distribution network de-icing devices when icing is required, regular de-icing function tests need to be conducted on the devices during the design and development process, before new products leave the factory, and before each winter for existing equipment. In particular, load-bearing operation tests should be conducted under various de-icing conditions for lines of different lengths and types.

[0003] When testing the load characteristics of power transmission and distribution de-icing devices, it is necessary not only to examine the full-load rated operating characteristics but also to assess the load characteristics under different load conditions, thereby comprehensively evaluating the functionality and operational capabilities of the de-icing device. For transmission and distribution lines of different lengths and types, the magnitude of the de-icing current mainly depends on the conductor specifications and is independent of the line length. That is, the de-icing current is basically determined for the same conductor specification. This requires the test load to be able to output a large load current under different operating voltages, especially at lower voltages, to test the voltage and current regulation capabilities of the de-icing device. However, the current load testing method for de-icing devices mainly configures the rated voltage and current parameters of the load system according to the highest test voltage and the highest test current. This load can only obtain the rated current under the rated output voltage. However, when the input voltage is lower than the rated voltage, it can only obtain a small load current that is much lower than the rated current. It is difficult to complete the test under the condition of lower de-icing voltage corresponding to a shorter de-icing line. On the other hand, if the load unit is configured according to the rated current obtained under the lower voltage, the rated capacity of the load will be much greater than the capacity of the de-icing device, even several times or tens of times the rated capacity, resulting in a large load capacity, high cost, large size, and poor economy.

[0004] Therefore, how to obtain a large current load under wide input voltage variations and how to flexibly adjust the current magnitude as needed to simulate the load-carrying characteristics of the ice-melting device when melting ice on different lines has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a load simulation system and operating method for simulating the de-icing characteristics of power transmission and distribution lines. This system is used to simulate the load characteristics of different types and lengths of power transmission and distribution lines during de-icing, thereby testing the load-bearing operating characteristics of the de-icing device for de-icing different lines.

[0006] In a first aspect, the present invention provides a load simulation system for de-icing characteristics of power transmission and distribution lines, comprising: a positive terminal and a negative terminal, wherein the positive terminal is connected to the positive terminal of a de-icing device, the negative terminal is connected to the negative terminal of the de-icing device, the positive terminal is connected to a positive busbar, the negative terminal is connected to a negative busbar, and a plurality of impedance units are included between the positive busbar and the negative busbar; Based on the expected de-icing voltage input at the positive port Adjust the series and parallel combination state of the multiple impedance units.

[0007] Optionally, each of the impedance units is arranged at intervals along the length direction of the negative busbar.

[0008] Optionally, each impedance unit includes an electrical disconnect switch, a first movable connection line, a resistor, and a second movable connection line. In each impedance unit, the upper end of the electrical disconnect switch is connected to the positive busbar, the upper end of the resistor in each impedance unit is fixedly connected to the lower end of the first movable connection line, and the lower end of the resistor in each impedance unit is fixedly connected to the upper end of the second movable connection line. The upper end of the first movable connection line in the current impedance unit is connected to the lower end of the electrical disconnect switch in the same impedance unit or the lower end of the resistor in another impedance unit, and the lower end of the second movable connection line in the current impedance unit is connected to the upper end of the resistor in another impedance unit or the negative busbar.

[0009] Optionally, at least one of the electrical disconnect switches in the plurality of impedance units is a high-frequency switching semiconductor switch, which controls the average current of the impedance unit in the branch by controlling its duty cycle. At least one of the electrical disconnect switches in each impedance unit is an air switch, which is used to obtain the base current for graded switching on and off.

[0010] Optionally, when the expected de-icing voltage When the rated voltage of a single impedance unit is not exceeded, multiple impedance units are connected in parallel, and the load current is adjusted by regulating the opening and closing state of the electrical disconnect switch in each impedance unit; wherein, the two ends of the first movable connection line in each impedance unit are respectively connected to the electrical disconnect switch and the resistor in the impedance unit, and the two ends of the second movable connection line in each impedance unit are respectively connected to the resistor and the negative bus in the impedance unit. When the expected ice-melting voltage When the voltage exceeds the rated voltage of a single impedance unit, the simulated load system for de-icing characteristics of the transmission and distribution line includes n parallel branches, and each branch includes m impedance units connected in series, where m and n are both positive integers. Then adjust the opening and closing state of the electrical disconnect switch in the first impedance unit of each branch to adjust the number of branches and the load current. In each of the branch circuits, the upper end of the first movable connection line in the first impedance unit is connected to the electrical disconnect switch, and the upper end of the first movable connection line in the other impedance units is connected to the lower end of the resistor in the previous impedance unit; the lower end of the second movable connection line in the last impedance unit is connected to the negative busbar, and the lower end of the second movable connection line in the other impedance units is connected to the upper end of the resistor in the next impedance unit.

[0011] Optionally, each of the branches has the same impedance value, rated current carrying capacity, and rated withstand voltage.

[0012] Optionally, the number of impedance units is a first preset value.

[0013] Optionally, the parameters and quantity of each impedance unit are designed based on the rated voltage and rated current of the load system under full-load operating conditions. The parameters of the impedance unit include the rated withstand voltage. Rated current capacity and impedance value When the simulated load system for de-icing characteristics of the transmission and distribution lines includes n parallel branches, the rated withstand voltage of each group of impedance units in each branch is... Rated current capacity and impedance value Calculate and set according to the following formula:

[0014] The rated current of the load system is simulated to represent the de-icing characteristics of the transmission and distribution lines. The rated voltage of the load system is used to simulate the de-icing characteristics of the power transmission and distribution line.

[0015] Optionally, when the input is the expected de-icing voltage When the current changes over a large range, the de-icing characteristics of the transmission and distribution lines should be checked to simulate the load system at the lowest input voltage. To obtain the expected de-icing current The ability, and its assessment criteria are:

[0016] When the current of the impedance unit in the current series-parallel configuration does not satisfy the above formula, the number of parallel groups n in the branch or the number of series resistors m in each branch should be adjusted, and the parameters of each impedance unit should be redesigned until the expected ice-melting current is achieved. The above conditions must be met.

[0017] Based on the same inventive concept, this invention provides an operation method for a transmission and distribution line de-icing characteristic simulation load system, applying the aforementioned transmission and distribution line de-icing characteristic simulation load system, including: Before load operation, based on the expected de-icing voltage and expected de-icing current The magnitude of the impedance is adjusted to change the series and parallel combination state of each impedance unit, where, When the expected ice-melting voltage When the voltage does not exceed the rated voltage of a single impedance unit, the impedance units are directly connected in parallel; When the expected ice-melting voltage When the voltage is greater than the rated voltage of a single impedance unit, the resistors in m impedance units are connected in series to form a branch, and n branches are connected in parallel, where m and n are both positive integers; Based on the expected ice-melting voltage and expected de-icing current Determine the rated withstand voltage of each group of impedance units in the branch. Rated current capacity and impedance value ; The de-icing characteristics of the transmission and distribution lines were verified under simulated load system at the lowest input voltage. To obtain the expected de-icing current The rated current of the load system is simulated by the de-icing characteristics of the power transmission and distribution lines. The size relationship between them is used to determine the number of branches put into use and the number of impedance units connected in series in each branch.

[0018] The technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art: The present invention provides a load simulation system and operating method for simulating the de-icing characteristics of power transmission and distribution lines, comprising: a positive port and a negative port, wherein the positive port is connected to the positive terminal of the de-icing device, the negative port is connected to the negative terminal of the de-icing device, the positive port is connected to the positive busbar, and the negative port is connected to the negative busbar. Multiple impedance units are included between the positive and negative busbars. The series-parallel combination of the multiple impedance units is adjusted according to the expected de-icing voltage input to the positive port. This allows for rapid and flexible adjustment of the series-parallel combination of the multiple impedance units, thereby simulating the de-icing load characteristics of power transmission and distribution lines of different specifications and lengths. This achieves a basically constant load current over a wide input voltage range, avoiding the problem of excessively high rated load power caused by balancing both low-voltage high-current and high-voltage high-current operating conditions.

[0019] This solution can obtain continuously adjustable load current over a wide voltage and current range, without the graded control deviations caused by conventional series-parallel combinations. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The diagram shown is a structural schematic of a load simulation system for de-icing characteristics of power transmission and distribution lines provided in an embodiment of the present invention. Figure 2 The diagram shown is a connection diagram of one unit connected in series in each group according to an embodiment of the present invention; Figure 3 The diagram shown is a series-parallel connection diagram when each group consists of two units connected in series, as provided in an embodiment of the present invention. Figure 4 The diagram shown is a series-parallel connection diagram when each group consists of 3 units connected in series, as provided in an embodiment of the present invention. Figure 5 The diagram shown is a series-parallel connection diagram when each group consists of 4 units connected in series, as provided in an embodiment of the present invention. Figure 6 The figure shows the maximum load current curves of the ice-melting characteristic simulation load system provided in the embodiment of the present invention under different input voltages. Detailed Implementation

[0023] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0025] Figure 1 The diagram shown is a structural schematic of a load simulation system for de-icing characteristics of power transmission and distribution lines according to an embodiment of the present invention. Please refer to it. Figure 1 This invention provides a load simulation system 100 for simulating the de-icing characteristics of power transmission and distribution lines, comprising: a positive port and a negative port. The positive port is connected to the positive terminal of a de-icing device, and the negative port is connected to the negative terminal of the de-icing device. A main switch and a current measuring unit are provided between the positive port and the positive busbar. The negative port is connected to the negative busbar. A voltage measuring unit is configured between the positive and negative ports. Multiple impedance units 01 with variable series and parallel connections are included between the positive and negative busbars. The system is based on the expected de-icing voltage input at the positive port. Adjust the series and parallel combination state of multiple impedance units 01.

[0026] The power transmission and distribution line de-icing characteristic simulation load system 100 provided by the present invention can quickly and flexibly adjust the series and parallel combination state of multiple impedance units 01, thereby simulating the de-icing load characteristics of power transmission and distribution lines under different specifications and lengths, and thus obtaining a basically constant load current within a wide input voltage range, avoiding the problem of excessive load rated power caused by taking into account both low voltage high current and high voltage high current operating conditions.

[0027] Each impedance unit is arranged sequentially at intervals along the length of the negative busbar.

[0028] Each impedance unit 01 includes an electrical disconnect switch K, a first movable connection line L1, a resistor R, and a second movable connection line L2. The upper end of the electrical disconnect switch K in each impedance unit 01 is connected to the positive bus, the upper end of the resistor R in each impedance unit 01 is fixedly connected to the lower end of the first movable connection line L1, and the lower end of the resistor R in each impedance unit 01 is fixedly connected to the upper end of the second movable connection line L2.

[0029] The upper end of the first movable connection line L1 in the current impedance unit 01 is connected to the lower end of the electrical disconnect switch K in the same impedance unit 01 or the lower end of the resistor R in another impedance unit 01. The lower end of the second movable connection line L2 in the current impedance unit 01 is connected to the upper end of the resistor R in another impedance unit 01 or the negative busbar.

[0030] That is, the lower end of the electrical disconnect switch K is fixedly connected to the upper end of the first movable connection line L1 in this impedance unit 01, and the lower end of the resistor R is fixedly connected to the upper end of the second movable connection line L2 in this impedance unit 01. The lower end of the second movable connection line L2 can be selected to be connected to the upper end of the negative bus in this impedance unit 01 or the resistor R in the next adjacent impedance unit 01 as needed.

[0031] By adjusting the switching state of the electrical disconnect switch K in each impedance unit 01 and the connection position of the lower end of the first movable connection line L1 and the lower end of the second movable connection line L2, the series and parallel combination state of the resistor R in the impedance unit 01 and the resistor R in other impedance units 01 can be quickly changed to form a composite load with several resistors R in series and multiple groups in parallel, thereby adjusting the overall equivalent resistance R of the simulated load and its load current.

[0032] Under the given operating voltage and expected load current, the series and parallel connection states of each impedance unit 01 are changed according to the magnitude of the operating voltage and the magnitude of the load current: when the input voltage is high, each group should have two or more resistors R connected in series to increase its overall withstand voltage, and different load currents can be obtained by grouping them into or out; when the input voltage is low, the number of series resistors R is reduced until there is only one unit in each group, but the number of parallel groups is increased, thereby significantly reducing the overall resistance and improving the current output capability under low voltage.

[0033] Please refer to Figure 1 At least one of the multiple impedance units 01 has an electrical disconnect switch K that is a high-frequency switching semiconductor switch. The semiconductor switch controls the average current of the impedance unit 01 in its branch by controlling its duty cycle. At least one electrical disconnect switch K in each impedance unit 01 is an air switch. The air switch is used to obtain the base current for graded switching on and off.

[0034] Specifically, in multiple impedance units 01, at least one electrical disconnect switch K employs a semiconductor switching device such as an IGBT capable of high-frequency switching, while other switches can be conventional air switches that do not require frequent switching. A base current for graded switching is obtained by adjusting the state of the conventional air switch, and the current of the branch is continuously adjusted between 0 and its maximum constant current by adjusting the high-frequency switching ratio of the semiconductor switch. The two work together to achieve the control of any continuous operating current point within the allowable voltage and current range.

[0035] This solution can obtain continuously adjustable load current over a wide voltage and current range, without the graded control deviations caused by conventional series-parallel combinations.

[0036] Figure 2The diagram shown is a connection diagram of each group connected in series with one resistor, according to an embodiment of the present invention. Figure 3 The diagram shown is a series-parallel connection diagram with two resistors connected in series in each group, provided by an embodiment of the present invention. Figure 4 The diagram shown is a series-parallel connection diagram with three resistors connected in series in each group, provided by an embodiment of the present invention. Figure 5 The diagram shown illustrates the series-parallel connection of four resistors in each group according to an embodiment of the present invention. Please refer to... Figures 1 to 5 The series and parallel connection states of each impedance unit 01 are determined according to the expected ice-melting voltage. Adjustment; When the expected de-icing voltage When the rated voltage of a single impedance unit 01 is not exceeded, multiple impedance units 01 are connected in parallel, and the load current is adjusted by regulating the open / closed state of the electrical disconnect switch K in each impedance unit 01. Specifically, the upper end of the first movable connection line L1 in each impedance unit 01 is connected to the lower end of the electrical disconnect switch K in that impedance unit 01, the lower end of the first movable connection line L1 in each impedance unit 01 is connected to the upper end of the resistor R in that impedance unit 01, and the upper end of the second movable connection line L2 in each impedance unit 01 is connected to the lower end of the resistor R in that impedance unit 01. The lower end of the second movable connection line L2 in each impedance unit 01 can be selectively connected to the negative busbar, allowing the impedance units 01 to operate in parallel, and the load current is adjusted by regulating the open / closed state of the electrical disconnect switch K in each impedance unit 01. Figure 1 and Figure 2 The illustration shows a case where each impedance unit 01 contains only one resistor R, and all impedance units 01 are connected in parallel. In this embodiment, the current of the load device can be adjusted by regulating the number of impedance units 01 and the duty cycle of the IGBT semiconductor switch.

[0037] When the expected de-icing voltage When the voltage is greater than the rated voltage of a single impedance unit 01, the power transmission and distribution line de-icing characteristic simulation load system 100 includes n parallel branches, each branch includes m series impedance units 01, where m and n are both positive integers. Then, the opening and closing state of the electrical disconnect switch K in the first impedance unit 01 in each branch is adjusted to regulate the number of branches connected and the magnitude of the load current.

[0038] In each branch, the upper end of the first movable connection line L1 in the first impedance unit 01 is connected to the electrical disconnect switch K, and the upper end of the first movable connection line L1 in other impedance units 01 is connected to the lower end of the resistor R in the previous impedance unit 01; the lower end of the second movable connection line L2 in the last impedance unit 01 is connected to the negative bus, and the lower end of the second movable connection line L2 in other impedance units 01 is connected to the upper end of the resistor R in the next impedance unit 01.

[0039] By adjusting the lower end of the first movable connection line L1 and the lower end of the second movable connection line L2 of the impedance unit 01, two or more impedance units 01 are connected in series to form a branch, and multiple branches are connected in parallel, with several impedance units 01 connected in series in each branch. Then, the opening and closing state of the electrical disconnect switch K of the first impedance unit 01 in each group is adjusted to regulate the number of groups and the load current.

[0040] Specifically, when i impedance units 01 in each group need to be connected in series, the lower end of the first movable connection line L1 of the 1st, i+1th, 2i+1th... impedance units 01 is connected to the upper end of the resistor R in that impedance unit 01. The lower end of the second movable connection line L2 of the 1st to i-1th, i+1th to 2i-1th, 2i+1th to 3i-1th... impedance units 01 is connected to the upper end of the next adjacent resistor R. The lower end of the second movable connection line L2 of the ith, 2ith, 3ith... impedance units 01 is connected to the negative busbar, thus forming i impedance units 01 connected in series to form a branch. The electrical disconnect switch K of the 1st impedance unit 01 is used to control the on / off state of the impedance units 01 in this branch. i is an integer greater than or equal to 1.

[0041] Please refer to Figure 3 , Figure 3 The diagram shows the case where two impedance units 0 and 1 are connected in series in each branch, and the six branches are connected in parallel; please refer to the diagram. Figure 4 , Figure 4 The diagram shows the case where three impedance units 01 are connected in series in each branch, and four branches are connected in parallel; please refer to the diagram. Figure 5 , Figure 5 The diagram shows the case where 4 impedance units 01 are connected in series in each branch, and 3 branches are connected in parallel, etc., which will not be listed here. This invention does not limit the number of impedance units 01 connected in series or the number of branches connected in parallel in each branch, nor does it limit the number of impedance units 01 in the power transmission and distribution line de-icing characteristic simulation load system 100 or the actual number of branches put into use. The specific requirements shall prevail.

[0042] Please refer to Figures 1 to 5 The impedance value of impedance unit 01 in each branch and rated current capacity Rated withstand voltage same.

[0043] When designing the parameters of each impedance element 01, the impedance value of each impedance element 01 is selected. and rated current capacity Rated withstand voltage Similarly, when multiple impedance units 01 are connected in series to form a branch, the current carrying capacity of each branch is directly equal to the current carrying capacity of the single unit, and the withstand voltage of each branch is equal to the number of impedance units 01 connected in series in each branch multiplied by the rated voltage of the single unit.

[0044] Please refer to Figures 1 to 5 The number of impedance units 01 is a first preset value. For example, the number of impedance units 01 is a common multiple of 2, 3, and 4, so that they can be divided into groups without any idle units. Figures 1 to 5 This illustration only shows the case where the load system includes 12 impedance units 01, but it is not limited to this. It may also include other numbers of impedance units 01, as long as the number of impedance units 01 is a common multiple of 2, 3, and 4.

[0045] The number of impedance units 01 should ideally be a common multiple of 2, 3, 4, etc., to facilitate power unit grouping when the input voltage does not exceed the rated voltage. Optionally, in some other embodiments, a small number of redundant impedance units can be reserved to facilitate replacement in case of failure of some impedance units 01, avoiding the overall failure to meet expectations due to the failure of individual impedance units 01.

[0046] Please refer to Figures 1 to 5 The rated parameters and quantity of each impedance unit 01 are based on the rated voltage of the load system. Rated current Designed for full-load operation, the parameters of impedance unit 01 include rated withstand voltage. Rated current capacity and impedance value When the load system 100 simulating the de-icing characteristics of transmission and distribution lines includes n parallel branches, the rated withstand voltage of each impedance unit 01 in each branch is... Rated current capacity and impedance value Calculate and set according to the following formula:

[0047] To simulate the de-icing characteristics of power transmission and distribution lines, the rated current of a load system 100 is used. The rated voltage of load system 100 is used to simulate the de-icing characteristics of power transmission and distribution lines.

[0048] When the expected de-icing voltage is input When the current varies over a large range, in order to ensure that the required de-icing current amplitude can be obtained within a given voltage range, the operating current when all impedance units 01 are fully engaged at the lowest input voltage must not be lower than the rated de-icing current. This requires verifying the de-icing characteristics of the transmission and distribution line by simulating the load system 100 at the lowest input voltage. To obtain the expected de-icing current The evaluation criteria are as follows:

[0049] When the current of impedance unit 01 in the current series-parallel connection mode does not satisfy the above equation (2), adjust the number of parallel groups in the branch, or adjust the number of series resistors R in impedance unit 01 in each branch, until the expected ice-melting current is reached. The above conditions must be met. That is, when the existing configuration does not meet the above equation (2), the numerical distribution of m and n can be adjusted appropriately or the impedance can be reduced. Based on the above formula (1), redesign the parameters of each unit until the expected melting current is reached. The above conditions must be met.

[0050] Please refer to Figures 1 to 5 This invention provides an operation method for a transmission and distribution line de-icing characteristic simulation load system 100, used to operate the transmission and distribution line de-icing characteristic simulation load system 100 as described above, including: Before load operation, based on the expected de-icing voltage and expected de-icing current The size of each impedance unit 01 is adjusted to determine the number of groups, where the expected melting voltage is... When the voltage does not exceed the rated voltage of a single impedance unit 01, all impedance units 01 are directly connected in parallel. That is, the grouping method and series / parallel connection status of each impedance unit 01 are adjusted. The number of resistors R connected in series in each branch should be based on the expected ice-melting voltage. With the rated withstand voltage of impedance unit 01 The ratio is obtained by rounding up; the number of parallel groups of the branches to be fixed should be based on the expected ice-melting current. The ratio of the current in each branch at a given voltage to the given voltage is rounded down. If the ratio is not divisible, a set of IGBT semiconductor switches is activated. At that time, i resistors R in each branch are connected in series. The impedance unit 01 is divided into m×n / i groups of branches. The first, i+1, 2i+1... electrical disconnect switches K are closed, and the remaining electrical disconnect switches K are kept open. The i, 2i, 3i... second movable connection lines L2 are connected to the negative bus. The other second movable connection lines L2 are connected to the upper end of the next adjacent resistor R respectively. i is a natural number.

[0051] Please refer to Figure 1 and Figure 2 In an optional embodiment provided by the present invention, when the expected de-icing voltage is... < In this case, each impedance unit 01 can be configured with only one resistor R per group, and all impedance units 01 can be used in parallel. By controlling the opening and closing of each electrical disconnect switch K one by one, 1, 2, ..., m×n impedance units 01 can be grouped and put into operation as needed, each corresponding to an equivalent load impedance equal to the rated impedance. , , …, lowest impedance Maximum load current can reach Combined with the control of a high-frequency on / off switch, it is possible to obtain 0 to Any load current between.

[0052] When the expected de-icing voltage When the voltage exceeds the rated voltage of a single impedance unit 01, the resistors R in m impedance units 01 are connected in series to form a branch, and n branches are connected in parallel, where m and n are both positive integers; based on the expected ice-melting voltage... and expected de-icing current Determine the rated withstand voltage of each impedance unit 01 in the branch. Rated current capacity and impedance value Verify the de-icing characteristics of power transmission and distribution lines using a simulated load system 100 at the lowest input voltage. To obtain the expected de-icing current The rated current of the load system 100 is simulated with the de-icing characteristics of power transmission and distribution lines. The size relationship between them is used to determine the number of branches to be put into use and the number of impedance units 01 in series in each branch.

[0053] Please refer to Figure 3 In another optional embodiment provided by the present invention, when the input voltage In this case, every two impedance units 01 can be set up as a branch for parallel use, resulting in a total of mn / 2 branches. Even-numbered switches such as K2, K4, K6… remain open, while odd-numbered switches such as K1, K3, K5… are switched on and off as needed to group the components into 1, 2, …, m×n / 2 groups, each corresponding to an equivalent load impedance equal to the rated impedance. , , …, lowest impedance Maximum load current can reach Combined with the control of a high-frequency on / off switch, it is possible to obtain 0 to Any load current between.

[0054] Please refer to Figure 4 In another optional embodiment provided by the present invention, when the input voltage In this case, every 3 impedance units 01 can be set up as a branch for parallel use, resulting in a total of mn / 3 branches. Switches K2, K3, K5, K6… etc. remain open, while switches K1, K4,… etc. are switched on and off as needed to group the components into 1, 2,…m×n / 3 groups, each corresponding to an equivalent load impedance equal to the rated impedance. , , …, lowest impedance Maximum load current can reach Combined with the control of a high-frequency on / off switch, it is possible to obtain 0 to Any load current between.

[0055] In another optional embodiment provided by the present invention, when the input voltage When using this method, each i impedance unit 01 can be configured as a group of branches for parallel use, resulting in a total of mn / i groups. Switches K1, K(i+1), K(2i+1), ..., are activated as needed, while other switches remain open. The activation / deactivation of switches K1, K(i+1), K(2i+1), ..., etc., groups 1, 2, ..., m×n / i are used as needed, each corresponding to an equivalent load impedance equal to the rated impedance. , , ..., minimum impedance Maximum load current can reach Combined with the control of a high-frequency on / off switch, it is possible to obtain 0 to Any load current between.

[0056] The above are merely examples, and the present invention does not limit them. The specific grouping and series-parallel connection methods can be adjusted according to the actual situation.

[0057] After determining the grouping method, disconnect all electrical disconnect switches K, i+1, 2i+1..., and close the main switch to connect the load system to the de-icing device under test, and set the expected de-icing voltage at the output of the de-icing device under test. At the same time, sequentially engage the (i+1), (2i+1), ... electrical disconnect switches K; gradually increase the number of branches engaged in each group, and observe the input current value of the ammeter at the positive bus input terminal until the input current value is lower than the expected de-icing current. At that time, and the input current value after adding another branch exceeded the expected de-icing current. At that time, disconnect the electrical disconnect switch K of this group; then adjust the IGBT semiconductor switch of the first group of impedance unit 01, gradually increasing the duty cycle of the IGBT semiconductor switch until the input current value is exactly equal to the expected de-icing current. Then, a continuous test under the predetermined ice-melting current was conducted.

[0058] Specifically, after determining the grouping method, all electrical disconnect switches K are disconnected, and the entire simulated load system 100 for de-icing characteristics of the power transmission and distribution line is connected to the de-icing device under test. When the de-icing device outputs its rated voltage, each group of branches is connected one by one through the circuit breaker until the input current is slightly lower than the expected current or exceeds it after connecting another group of branches. At this point, the branch group is disconnected and returned to its original position. Then, the high-frequency switching switch is adjusted to gradually increase the duty cycle of the high-frequency switching switch so that the actual output current is exactly equal to the expected current. Then, a continuous test is conducted under the predetermined de-icing current.

[0059] When it is necessary to conduct sudden load increase and decrease tests for de-icing, the main input switch can be suddenly disconnected to remove all loads after adjusting the grouping method and the duty cycle control parameters of the high-frequency switch as described above. Then, the main switch can be turned on to conduct the sudden load increase test of the expected voltage and current. After the switch is turned on and the system is running stably, it can be turned off to conduct the sudden load decrease test.

[0060] Effect verification Please combine Figure 1 This embodiment requires simulating ice-melting lines with lengths ranging from 0.3 to 4 km, conductor types from LGJ-35 to LGJ-240 and their mixed types, a maximum ice-melting current of 1000A, and an ice-melting voltage range of 30V to 540V. The maximum load power is 540V×1000A=540kW. The load is required to meet the ice-melting load test requirements of distribution network lines of different lengths and types within the given range.

[0061] Figure 6 The figure shows the maximum load current curves of the ice-melting characteristic simulated load system provided in this embodiment of the invention under different input voltages. Please refer to... Figure 5 and Figure 6 To meet the above requirements for simulating the characteristics of the de-icing load, this load simulation device includes 12 impedance units 01. Under rated operating conditions, each group of 4 impedance units 01 is connected in series to form one branch, and 3 branches are connected in parallel. Each impedance unit 01 has a rated voltage of 540V / 4=135V, a rated current of 4 / 3×1000 / 3=444A, a rated impedance of 135V / 444A=0.304Ω, and a rated power of 135V×444A=60kW. The total power of the entire load is 60kW×12=720kW. Each air switch is selected with a rated voltage of not less than 540V and a current of not less than 444A. When all 12 impedance units 01 are connected in parallel, the load current at the minimum input voltage of 30V is:

[0062] This means that this method can meet the rated output voltage requirement at the lowest voltage.

[0063] When the input voltage is in different ranges, the combined wiring methods for this simulated load are as follows. when When the voltage is ≤135V, each group has one impedance unit 01 connected in series, and 12 groups are used in parallel (e.g. Figure 2 As shown, the lower end of the second movable connecting line L2 of each of the 12 impedance units 01 is connected to the negative bus. The 12 impedance units 01 are grouped and activated by switching K1, K2...K12, with a minimum impedance of 0.025Ω. Theoretically, this mode can generate a maximum load current of 5333A. However, considering that exceeding the rated load current of 1000A is unnecessary in practice, in practical applications, only a portion of the impedance units 01 can be switched on based on the input voltage and current requirements. Combined with the control of a high-frequency on / off switch, any load current between 0 and 1000A can be obtained.

[0064] When 135V < When the voltage is <270V, two resistors R in each branch are connected in series and used in parallel in 6 groups of branches (e.g., Figure 3 As shown in the diagram, the lower end of the second movable connection line L2 of the odd-numbered impedance units 01 is connected to the upper port of the resistor R of the next adjacent impedance unit 01. The electrical disconnect switch K of the even-numbered impedance units 01 remains open. The lower end of the second movable connection line L2 of the even-numbered impedance units 01 is connected to the negative busbar. Groups 1, 2, ..., 6 are activated by switching K1, K3...K11, etc. The minimum equivalent impedance is 0.10Ω. The theoretical maximum load current in this mode is 2700A. However, considering that exceeding the rated load current of 1000A is unnecessary in practice, in practical applications, only some impedance units 01 can be switched on according to the input voltage and current requirements. With the control of a high-frequency on / off switch, any load current between 0 and 1000A can be obtained.

[0065] When 270V < When the voltage is <405V, the three resistors R in each branch are connected in series and used in parallel in four groups of branches (e.g., Figure 4 As shown), groups 1, 2, ... 4 are activated, with equivalent impedances of 3 / 1, 3 / 2... 3 / 4 of the rated impedance, and a minimum impedance of 0.225Ω. In this mode, the theoretical maximum load current is 1500A. However, considering that exceeding the rated load current of 1000A is unnecessary in practice, in practical applications, only some impedance unit 01 switches can be activated, and with the control of a high-frequency on / off switch, any load current between 0 and 1000 can be obtained.

[0066] When 405V < When the voltage is <540V, the four resistors R in each branch are connected in series and used in parallel in three groups of branches (e.g.) Figure 5 As shown), groups are deployed in sets 1, 2, ..., 3, with impedances of 1 / 4, 2 / 4...3 of the rated impedance, and a minimum impedance of 0.4Ω; in this mode, when 400V < For voltages below 540V, 1000A output current can be obtained by adjusting the number of branches connected, with a maximum of 1350A. However, considering that exceeding the rated load current of 1000A is unnecessary in practice, in practical applications, only some impedance unit 01 switches can be connected, and with the control of a high-frequency on / off switch, any load current between 0 and 1000 can be obtained.

[0067] Alternatively, it can be used in parallel with two groups of branches, each with 5 or 6 resistors R connected in series, and 1 or 2 groups can be connected, with a minimum impedance of 0.75Ω; however, in this mode, due to the small number of parallel groups and the current limiting effect of adjacent units, it cannot obtain a current exceeding 888A. It can also be used in parallel with one group, each with 5-12 resistors R connected in series, and 5-12 impedance units 01 connected in the group, with a maximum impedance of 3.6Ω; however, in this mode, due to the current limiting effect of units, it cannot obtain a current exceeding 444A.

[0068] Based on the aforementioned operating conditions 1, 2, 3, 4, and 5, by appropriately grouping and connecting different impedance units 01, a current of no less than 1000A can be obtained within the 25-540V range, thus completing load tests under different operating conditions; it can even complete overload tests up to 540V / 1333A / 720kW. From an impedance perspective, a wide impedance range of 0.025Ω to 3.6Ω can be obtained, thereby simulating different load conditions; from a utilization perspective, the rated power of the load configuration 60kW×12=720kW is approximately 1.33 times the rated output power 540V×1000A=540kW, and the hardware configuration utilization rate is 3 / 4=75%.

[0069] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A load simulation system for de-icing characteristics of power transmission and distribution lines, characterized in that, include: The device includes a positive port and a negative port. The positive port is connected to the positive terminal of the ice-melting device, and the negative port is connected to the negative terminal of the ice-melting device. The positive port is connected to the positive busbar, and the negative port is connected to the negative busbar. Multiple impedance units are included between the positive busbar and the negative busbar. Based on the expected de-icing voltage input at the positive port Adjust the series and parallel combination state of the multiple impedance units.

2. The load simulation system for de-icing characteristics of transmission and distribution lines according to claim 1, characterized in that, Each of the impedance units is arranged at intervals along the length of the negative busbar.

3. The load simulation system for de-icing characteristics of power transmission and distribution lines according to claim 1, characterized in that, Each impedance unit includes an electrical disconnect switch, a first movable connection line, a resistor, and a second movable connection line. In each impedance unit, the upper end of the electrical disconnect switch is connected to the positive busbar, the upper end of the resistor in each impedance unit is fixedly connected to the lower end of the first movable connection line, and the lower end of the resistor in each impedance unit is fixedly connected to the upper end of the second movable connection line. The upper end of the first movable connection line in the current impedance unit is connected to the lower end of the electrical disconnect switch in the same impedance unit or the lower end of the resistor in another impedance unit, and the lower end of the second movable connection line in the current impedance unit is connected to the upper end of the resistor in another impedance unit or the negative busbar.

4. The load simulation system for de-icing characteristics of power transmission and distribution lines according to claim 3, characterized in that, At least one of the electrical disconnect switches in the plurality of impedance units is a high-frequency switching semiconductor switch, and the semiconductor switch regulates the average current of the impedance unit in the branch by controlling its duty cycle. At least one of the electrical disconnect switches in each impedance unit is an air switch, which is used to obtain the base current for graded switching on and off.

5. The power transmission and distribution line de-icing characteristic simulation load system according to claim 3, characterized in that, When the expected de-icing voltage When the rated voltage of a single impedance unit is not exceeded, multiple impedance units are connected in parallel, and the load current is adjusted by regulating the opening and closing state of the electrical disconnect switch in each impedance unit; wherein, the two ends of the first movable connection line in each impedance unit are respectively connected to the electrical disconnect switch and the resistor in the impedance unit, and the two ends of the second movable connection line in each impedance unit are respectively connected to the resistor and the negative bus in the impedance unit. When the expected de-icing voltage When the voltage exceeds the rated voltage of a single impedance unit, the simulated load system for de-icing characteristics of the transmission and distribution line includes n parallel branches, and each branch includes m impedance units connected in series, where m and n are both positive integers. Then adjust the opening and closing state of the electrical disconnect switch in the first impedance unit of each branch to adjust the number of branches and the load current. In each of the branch circuits, the upper end of the first movable connection line in the first impedance unit is connected to the electrical disconnect switch, and the upper end of the first movable connection line in the other impedance units is connected to the lower end of the resistor in the previous impedance unit; the lower end of the second movable connection line in the last impedance unit is connected to the negative busbar, and the lower end of the second movable connection line in the other impedance units is connected to the upper end of the resistor in the next impedance unit.

6. The power transmission and distribution line de-icing characteristic simulation load system according to claim 5, characterized in that, The impedance values, rated current carrying capacity, and rated withstand voltage of the impedance units in each branch are the same.

7. The power transmission and distribution line de-icing characteristic simulation load system according to claim 1, characterized in that, The number of impedance units is a first preset value.

8. The power transmission and distribution line de-icing characteristic simulation load system according to claim 5, characterized in that, The parameters and quantity of each impedance unit are designed based on the rated voltage, rated current, and full-load operating conditions of the load system. The parameters of the impedance unit include the rated withstand voltage. Rated current capacity and impedance value When the simulated load system for de-icing characteristics of the power transmission and distribution line includes n parallel branches, the rated withstand voltage of each group of impedance units in each branch is... Rated current capacity and impedance value Calculate and set according to the following formula: The rated current of the load system is simulated to represent the de-icing characteristics of the transmission and distribution lines. The rated voltage of the load system is used to simulate the de-icing characteristics of the power transmission and distribution line.

9. The power transmission and distribution line de-icing characteristic simulation load system according to claim 8, characterized in that, When the expected de-icing voltage is input When the current changes over a large range, the de-icing characteristics of the transmission and distribution lines should be checked to simulate the load system at the lowest input voltage. To obtain the expected de-icing current The ability, and its assessment criteria are: When the current of the impedance unit in the current series-parallel configuration does not satisfy the above formula, the number of parallel groups n in the branch or the number of series resistors m in each branch should be adjusted, and the parameters of each impedance unit should be redesigned until the expected ice-melting current is achieved. The above conditions must be met.

10. A method for operating a load simulation system for simulating the de-icing characteristics of transmission and distribution lines, using the load simulation system for simulating the de-icing characteristics of transmission and distribution lines as described in any one of claims 1-9, characterized in that, include: Before load operation, based on the expected de-icing voltage and expected de-icing current The magnitude of the impedance is adjusted to change the series and parallel combination state of each impedance unit, where, When the expected de-icing voltage When the voltage does not exceed the rated voltage of a single impedance unit, the impedance units are directly connected in parallel; When the expected de-icing voltage When the voltage exceeds the rated voltage of a single impedance unit, the resistors in m impedance units are connected in series to form a branch, and n branches are connected in parallel, where m and n are both positive integers. Based on the expected ice-melting voltage and expected de-icing current Determine the rated withstand voltage of each group of impedance units in the branch. Rated current capacity and impedance value ; The de-icing characteristics of the transmission and distribution lines were verified under simulated load system at the lowest input voltage. To obtain the expected de-icing current The rated current of the load system is simulated by the de-icing characteristics of the power transmission and distribution lines. The size relationship between them is used to determine the number of branches put into use and the number of impedance units connected in series in each branch.

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