A multi-loop current equalization method

Abstract

The application discloses a kind of multi-loop current equalization methods, belong to current control technical field.The application establishes line resistance calculation model based on the number of lapping bolt, cable length, cable cross-sectional area, cable resistivity, copper bar length, copper bar cross-sectional area, copper bar resistivity, lapping bolt contact resistance;With the lowest reference cost as target, based on cable material cost and copper bar lapping cost, establish objective function;Based on objective function and line resistance calculation model, adjust the cable length and the number of lapping bolt of each loop, until the current deviation rate of each loop is less than 5%, obtain the optimal cable length and optimal lapping bolt number of each loop;Based on the actual current of each loop under the condition, the actual current deviation rate of each loop is calculated, if actual current deviation rate is not less than 5%, then return to execute step S3 until actual current deviation rate is less than 5%.The application can greatly reduce the implementation cost while realizing multi-loop current equalization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current control, and particularly relates to a current balancing method for multiple circuits. BACKGROUND

[0002] In a power system of a data center and a computing power center, due to differences in resistances of circuit cables connected to the same UPS device and different UPS devices, the currents of the circuits are unbalanced, so that some devices bear too high or too low currents, which not only affects the performance of the devices, but also may even cause safety problems such as overheating and short circuit of the devices.

[0003] In order to ensure the relative balance of the currents, related technologies often need to use high-cost cable materials. Although these high-cost cable materials can reduce the resistance differences to a certain extent, they greatly increase the construction and operation costs of the data center and the computing power center. SUMMARY

[0004] The main purpose of the present application is to provide a current balancing method for multiple circuits, which aims to solve the technical problem of high cost of current balancing for multiple circuits in related technologies.

[0005] To achieve the above purpose, the present application provides a current balancing method for multiple circuits, which comprises the following steps:

[0006] S1, a line resistance calculation model is established based on the number of lap joint bolts, the cable length, the cable cross-sectional area, the cable resistivity, the copper bar length, the copper bar cross-sectional area, the copper bar resistivity and the contact resistance of the lap joint bolt:

[0007] ;

[0008] Wherein, represents the line resistance of the i-th circuit; represents the copper bar length of the i-th circuit; represents the cable length of the i-th circuit; represents the cable cross-sectional area; represents the cable resistivity; represents the copper bar resistivity; represents the copper bar cross-sectional area; represents the number of lap joint bolts of the i-th circuit; represents the contact resistance of a single lap joint bolt;

[0009] S2, a target function is established based on the cable material cost and the copper bar lap joint cost, with the lowest reference cost as the target:

[0010] ;

[0011] Wherein, Indicates the lowest reference cost; This indicates the material cost per unit volume of cable; Indicates the spacing between lap bolts; Indicates the width of the overlapping copper busbar; Indicates the thickness of the overlapping copper busbar; Indicates the density of copper; Indicates the unit price of copper;

[0012] S3. Based on the objective function and the line resistance calculation model, adjust the cable length and the number of lap bolts for each circuit until the current deviation rate of each circuit is less than 5%, and obtain the optimal cable length and the optimal number of lap bolts for each circuit.

[0013] S4. Calculate the actual current deviation rate of each circuit based on the optimal cable length and the optimal number of lap bolts. If the actual current deviation rate is not less than 5%, return to step S3 until the actual current deviation rate is less than 5% to complete the current balancing.

[0014] This invention establishes a line resistance calculation model and sets an objective function based on cable material cost and splicing cost. With a current deviation rate of less than 5%, it utilizes an optimization algorithm to adjust the cable length and the number of splicing bolts for each circuit. This allows for precise control of the line resistance of each circuit, thereby minimizing costs while reducing the differences in line resistance between circuits to within the required range, thus achieving current balancing across multiple circuits. Therefore, this invention significantly reduces implementation costs while achieving current balancing across multiple circuits. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating an embodiment of the multi-loop current balancing method of the present invention;

[0016] Figure 2 This is a detailed flowchart illustrating the current balancing process in an embodiment of the multi-loop current balancing method of the present invention.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] The inventive concept of this application is further illustrated below with reference to some specific embodiments and implementation methods.

[0020] This invention provides a multi-loop current balancing method, referring to... Figure 1 ,Figure 1 A flowchart of an embodiment of a multi-loop current equalization method of the present application.

[0021] In this embodiment, the multi-loop includes multiple loops connected to the same UPS device or multiple loops connected to different UPS devices, and the length difference between the loops in the multi-loop is less than 1 meter. The current equalization method of the multi-loop includes the following steps:

[0022] Step S1: Establish a line resistance calculation model based on the number of lapping bolts, cable length, cable cross-sectional area, cable resistivity, copper bar length, copper bar cross-sectional area, copper bar resistivity, and lapping bolt contact resistance:

[0023] ;

[0024] Wherein, represents the line resistance of the i-th loop; represents the copper bar length of the i-th loop; represents the cable length of the i-th loop; represents the cable cross-sectional area; represents the cable resistivity; represents the copper bar resistivity; represents the copper bar cross-sectional area; represents the number of lapping bolts of the i-th loop; represents the contact resistance of a single lapping bolt.

[0025] In step S1, the lapping bolt contact resistance is included in the line resistance calculation model based on the cable resistance and the copper bar resistance, so that the calculation model can better reflect the actual situation of the loop, thereby enabling fine and accurate calculation of the line resistance of the loop, laying a foundation for subsequent accurate adjustment of the line resistance.

[0026] Step S2: Establish a target function based on the cable material cost and the copper bar lapping cost, with the lowest reference cost as the target:

[0027] ;

[0028] Wherein, represents the lowest reference cost; represents the unit volume cable material cost; represents the lapping bolt spacing; represents the lapping copper bar width; represents the lapping copper bar thickness; represents the copper density; represents the copper unit price.

[0029] In step S2, by taking the sum of the cable material cost and the copper bar lap joint cost as the reference cost, a relationship between the reference cost and the cable length and the number of lap joint bolts can be established. On this basis, while adjusting the cable length and the number of lap joint bolts, the reference cost can also be taken into account to achieve the dual optimization of the current deviation rate and the line cost.

[0030] Step S3: based on the objective function and the line resistance calculation model, adjusting the cable length and the number of lap joint bolts of each loop until the current deviation rate of each loop is less than 5%, obtaining the optimal cable length and the optimal number of lap joint bolts of each loop.

[0031] As shown in Figure 2 , the step S3 specifically includes the following steps:

[0032] Step S31, based on the line resistance calculation model, calculating the initial line resistance and the initial short-circuit current of each loop to determine the reference current.

[0033] The step S31 specifically includes the following steps:

[0034] S31-1: inputting the cable cross-sectional area, the cable resistivity, the copper bar length, the copper bar cross-sectional area, the copper bar resistivity, the lap joint bolt contact resistance, the initial cable length and the initial number of lap joint bolts of each loop into the line resistance calculation model to obtain the initial line resistance of each loop, and calculating the initial short-circuit current of all loops according to the loop voltage.

[0035] S31-2: traversing all loops, randomly selecting one loop as the reference loop, and the corresponding initial short-circuit current is the reference current.

[0036] Step S32, based on the initial line resistance and the reference current, adjusting the cable length and the number of lap joint bolts of each loop so that the current deviation rate of each loop is less than 5%, obtaining multiple sets of adjustment results and the reference cost corresponding to each set of adjustment results; the adjustment result includes the adjusted cable length and the number of lap joint bolts of each loop.

[0037] The step S32 specifically includes the following steps:

[0038] S32-1: for all loops except the reference loop, based on the objective function and the initial line resistance, adjusting the cable length and the number of lap joint bolts under the constraint conditions that the loop length is not less than the corresponding minimum loop distance and the number of lap joint bolts is not less than the minimum number of lap joint bolts.

[0039] The minimum distance of the loop is set to the distance that can connect the two devices corresponding to the loop and has a specified cable allowance (for example, a cable allowance of 15 cm is reserved); and the minimum number of overlapping bolts is set to the number that meets the safety overlapping requirements of the copper bar (for example, at least 5 bolts at one overlapping position).

[0040] The step S32-1 specifically includes the following steps:

[0041] The difference between the initial line resistance of each loop and the line resistance of the reference loop is calculated to determine the resistance adjustment amount of the loop:

[0042] ;

[0043] wherein, represents the resistance adjustment amount of the ith loop; represents the line resistance of the reference loop; represents the initial line resistance of the ith loop.

[0044] The cable length adjustment amount and the bolt number adjustment amount corresponding to each loop are calculated based on the resistance adjustment amount:

[0045] ;

[0046] wherein, represents the cable length adjustment amount of the ith loop; represents the cable adjustment coefficient (used to control the adjustment range of the cable length, which can be adjusted by the user according to actual needs);

[0047] ;

[0048] wherein, represents the bolt number adjustment amount of the ith loop; represents the bolt adjustment coefficient (used to control the adjustment range of the bolt number, which can be adjusted by the user according to actual needs).

[0049] For each loop except the reference loop, the cable length is adjusted based on the cable length adjustment amount, and the overlapping bolt number is adjusted based on the bolt number adjustment amount, with the goal of minimizing the reference cost, so as to reduce the difference between the short-circuit current of each loop and the reference current.

[0050] Specifically, if the short-circuit current of the current loop is greater than the reference current, the cable length is reduced based on the corresponding cable length adjustment amount, and if the cable length cannot be reduced any more (i.e., the cable length cannot meet the constraint condition that the loop length is not less than the corresponding minimum loop distance after being reduced), the number of overlapping bolts is reduced based on the corresponding bolt number adjustment amount; if the short-circuit current of the current loop is less than the reference current, the number of overlapping bolts is increased based on the corresponding bolt number adjustment amount or the cable length is increased based on the corresponding cable length adjustment amount in response to the user's preset selection.

[0051] In the whole step S32-1, the cable length adjustment amount and the bolt number adjustment amount are set respectively and specifically according to the line resistance difference of each loop compared with the reference loop, which is used for the cable adjustment and the overlapping bolt number adjustment of the corresponding loop, so that more refined adjustment can be realized, and the current balance effect of the multi-loop is further improved.

[0052] S32-2: When the adjustment of all loops except the reference loop is completed, the reference deviation rate of the adjusted short-circuit current of each loop compared with the reference current is calculated, and if the reference deviation rate of a loop is not less than 5%, the loop returns to execute step S32-1 until the reference deviation rate is less than 5%.

[0053] S32-3: The current deviation rate of all adjusted loops is calculated based on the line resistance calculation model and formula one, and if the current deviation rate of a loop is not less than 5%, the step S32-1 is returned to execute until the current deviation rate is less than 5%, and the cable length and the number of overlapping bolts of the current loop are recorded.

[0054] Formula one:

[0055] ;

[0056] wherein, Ii represents the short-circuit current of the i-th loop; U represents the loop voltage; I represents the average short-circuit current of all loops; Ii represents the current deviation rate of the i-th loop.

[0057] S32-4: Based on the cable length and the number of overlapping bolts of the current loop, the current reference cost is calculated, and the step S31-2 is returned to execute until all loops have completed adjustment as the reference loop, and a plurality of reference costs are obtained.

[0058] Step S33: From the plurality of reference costs, the minimum reference cost is determined, the cable length of each loop corresponding to the minimum reference cost is taken as the optimal cable length, and the number of overlapping bolts corresponding to each loop is taken as the optimal number of overlapping bolts.

[0059] In the whole step S3, each loop is taken as a reference loop by traversing all loops through a multi-layer nested loop structure, and the cable length and the number of lap bolts of each loop are adjusted to optimize the difference of the line resistance of each loop compared with the reference loop, so that multiple optimization results are obtained for comparison and cost implementation to determine the best optimization result, thereby avoiding missing the best optimization result and further reducing the implementation cost of the multi-loop current equalization.

[0060] Step S4: calculating the actual current deviation rate of each loop based on the actual current of each loop under the condition of the optimal cable length and the optimal number of lap bolts, and if the actual current deviation rate is not less than 5%, returning to execute step S3 until the actual current deviation rate is less than 5%, and completing the current equalization.

[0061] In the embodiment, by establishing a line resistance calculation model, establishing a target function with the cable material cost and the lap cost, and adjusting the cable length and the number of lap bolts of each loop by using an optimization algorithm under the condition that the current deviation rate is less than 5%, the line resistance of each loop can be accurately controlled, so that the difference of the line resistance of each loop can be reduced to the required range while ensuring the lowest cost, so as to realize the current equalization of the multi-loop. Therefore, the present application can greatly reduce the implementation cost while realizing the current equalization of the multi-loop.

[0062] The above-mentioned embodiment numbers of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0063] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent flow transformation obtained by using the content of the specification and the drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A multi-loop current equalization method, characterized by, The length difference between the loops is less than 1 meter, and the method comprises the following steps: S1, based on the number of overlapping bolts, cable length, cable cross-sectional area, cable resistivity, copper bar length, copper bar cross-sectional area, copper bar resistivity, and overlapping bolt contact resistance, a line resistance calculation model is established; ； wherein, represents the line resistance of the i-th loop; represents the copper bar length of the i-th loop; represents the cable length of the i-th loop; represents the cable cross-sectional area; represents the cable resistivity; represents the copper bar resistivity; represents the copper bar cross-sectional area; represents the number of lapping bolts of the i-th loop; represents the contact resistance of a single lapping bolt; S2, taking the lowest reference cost as the target, a target function is established based on the cable material cost and the copper bar overlapping cost; ； wherein, represents the lowest reference cost; represents the cable material cost per volume; represents the overlap bolt spacing; represents the overlap copper bar width; represents the overlap copper bar thickness; represents the copper density; represents the copper unit price; S3, based on the target function and the line resistance calculation model, the cable length and the number of overlapping bolts of each loop are adjusted until the current deviation rate of each loop is less than 5%, and the optimal cable length and the optimal number of overlapping bolts of each loop are obtained; S4, based on the optimal cable length and the optimal number of overlapping bolts, the actual current deviation rate of each loop is calculated, and if the actual current deviation rate is not less than 5%, the step S3 is returned until the actual current deviation rate is less than 5%, and the current balancing is completed.

2. The multi-circuit current equalization method of claim 1, wherein, The S3 specifically comprises: Step S31, based on the line resistance calculation model, the initial line resistance and the initial short-circuit current of each loop are calculated to determine the reference current; Step S32, based on the initial line resistance and the reference current, the cable length and the number of overlapping bolts of each loop are adjusted so that the current deviation rate of each loop is less than 5%, and a plurality of adjustment results and the reference cost corresponding to each adjustment result are obtained; the adjustment result comprises the adjusted cable length and the number of overlapping bolts of each loop; Step S33, from the plurality of reference costs, the minimum reference cost is determined, the cable length of each loop corresponding to the minimum reference cost is taken as the optimal cable length, and the number of overlapping bolts corresponding to each loop is taken as the optimal number of overlapping bolts.

3. The multi-circuit current equalization method of claim 2, wherein, The S31 specifically comprises: S31-1, the cable cross-sectional area, the cable resistivity, the copper bar length, the copper bar cross-sectional area, the copper bar resistivity, the overlapping bolt contact resistance, the initial cable length and the initial number of overlapping bolts of each loop are input into the line resistance calculation model to obtain the initial line resistance of each loop, and the initial short-circuit current of all loops is calculated according to the loop voltage; S31-2, all loops are traversed, and one loop is randomly selected as a reference loop, and the corresponding initial short-circuit current is the reference current.

4. The multi-circuit current equalization method of claim 3, wherein, The S32 specifically comprises: S32-1, for all loops except the reference loop, based on the target function and the initial line resistance, the cable length and the number of overlapping bolts are adjusted under the constraint conditions that the loop length is not less than the minimum distance of the corresponding loop and the number of overlapping bolts is not less than the minimum number of overlapping bolts; S32-2, after the adjustment of all loops except the reference loop is completed, the reference deviation rate of the adjusted short-circuit current of each loop compared with the reference current is calculated, and if the reference deviation rate of a loop is not less than 5%, the step S32-1 is executed again for the loop until the reference deviation rate is less than 5%; S32-3, based on the line resistance calculation model and formula one, the current deviation rate of all adjusted loops is calculated, and if the current deviation rate of a loop is not less than 5%, the step S32-1 is executed again until the current deviation rate is less than 5%, and the current cable length and the number of overlapping bolts of each loop are recorded; S32-4, based on the cable length of the current loop and the number of lap joint bolts, the current reference cost is calculated, and the step S31-2 is returned to be executed until all loops are completed as reference loops, and a plurality of reference costs are obtained.

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