Multi-loop current balancing method

Abstract

The invention discloses a multi-loop current balancing method, and belongs to the technical field of current control. According to the method, a line resistance calculation model is established based on the number of lap joint bolts, cable length, cable sectional area, cable resistivity, copper bar length, copper bar sectional area, copper bar resistivity and lap joint bolt contact resistance; establishing a target function based on the cable material cost and the copper bar lap joint cost by taking the lowest reference cost as a target; 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%, and obtaining the optimal cable length and the optimal number of lap joint bolts of each loop; and S3, calculating the actual current deviation ratio of each loop based on the actual current of each loop under the condition, and if the actual current deviation ratio is not less than 5%, returning to execute the step S3 until the actual current deviation ratio is less than 5%. According to the invention, the realization cost can be greatly reduced while multi-loop current equalization is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of current control, and in particular to a multi-loop current balancing method. Background Art

[0002] In the power systems of data centers and computing centers, the resistance of the loop cables connected to the same UPS device and to different UPS devices varies, resulting in unbalanced currents in each loop. This causes some devices to be subjected to excessively high or low currents, which not only affects device performance but may even cause safety issues such as overheating and short circuits in severe cases.

[0003] To ensure relatively balanced current flow, related technologies often require the use of expensive cable materials. While these high-cost cable materials can reduce resistance differences to a certain extent, they significantly increase the construction and operating costs of data centers and computing centers. Summary of the Invention

[0004] The main purpose of the present invention is to provide a multi-circuit current balancing method, aiming to solve the technical problem of high cost of multi-circuit current balancing in related technologies.

[0005] To achieve the above object, the present invention provides a multi-circuit current balancing method, the method comprising the following steps:

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

[0007] ;

[0008] in, represents the line resistance of the i-th loop; Indicates the length of the copper busbar of the i-th circuit; represents the cable length of the i-th loop; Indicates the cross-sectional area of ​​the cable; Indicates the cable resistivity; Indicates the resistivity of copper busbar; Indicates the cross-sectional area of ​​the copper busbar; represents the number of lap bolts in the i-th circuit; Represents the contact resistance of a single lap bolt;

[0009] S2, with the lowest reference cost as the goal, establishes the objective function based on the cable material cost and copper busbar bonding cost:

[0010] ;

[0011] in, represents the lowest reference cost; Indicates the cable material cost per unit volume; Indicates the lap bolt spacing; Indicates the width of the overlapping copper busbar; Indicates the thickness of the overlapping copper busbar; Indicates copper density; Indicates the unit price of copper;

[0012] S3, based on the objective function and the line resistance calculation model, adjusting the cable length and the number of overlapping bolts of each loop until the current deviation rate of each loop is less than 5%, thereby obtaining the optimal cable length and the optimal number of overlapping bolts for each loop;

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

[0014] The present invention establishes a line resistance calculation model, establishes an objective function based on cable material cost and lap joint cost, and uses an optimization algorithm to adjust the cable length and number of lap joint bolts for each circuit, with the current deviation rate being less than 5%. This allows for precise control of the line resistance of each circuit, thereby minimizing the difference in line resistance between circuits to within the required range while ensuring the lowest cost, thereby achieving current balancing across multiple circuits. Therefore, the present invention can significantly reduce implementation costs while achieving multi-circuit current balancing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of a flow chart of an embodiment of a multi-circuit current balancing method of the present invention;

[0016] Figure 2 Schematic diagram of a detailed flow chart of the current balancing process in an embodiment of the multi-loop current balancing method of the present invention.

[0017] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0018] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

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

[0020] The embodiment of the present invention provides a multi-circuit current balancing method, referring to Figure 1 , Figure 1 The figure is a flow chart of an embodiment of a multi-loop current balancing method of the present invention.

[0021] In this embodiment, the multiple circuits include multiple circuits connected to the same UPS device or multiple circuits connected to different UPS devices, and the circuit length difference between the multiple circuits is less than 1 meter. The current balancing method for the multiple circuits includes the following steps:

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

[0023] ;

[0024] in, represents the line resistance of the i-th loop; Indicates the length of the copper busbar of the i-th circuit; represents the cable length of the i-th loop; Indicates the cross-sectional area of ​​the cable; Indicates the cable resistivity; Indicates the resistivity of copper busbar; Indicates the cross-sectional area of ​​the copper busbar; represents the number of lap bolts in the i-th circuit; Represents the contact resistance of a single lap bolt.

[0025] In step S1, based on the cable resistance and copper busbar resistance, the lap bolt contact resistance is incorporated into the line resistance calculation model, so that the calculation model can better reflect the actual situation of the loop, thereby enabling the precise and accurate calculation of the line resistance of the loop, laying the foundation for the subsequent precise adjustment of the line resistance.

[0026] Step S2: Taking the lowest reference cost as the goal, establish the objective function based on the cable material cost and the copper busbar connection cost:

[0027] ;

[0028] in, represents the lowest reference cost; Indicates the cable material cost per unit volume; Indicates the lap bolt spacing; Indicates the width of the overlapping copper busbar; Indicates the thickness of the overlapping copper busbar; Indicates copper density; Indicates the unit price of copper.

[0029] In step S2, the sum of the cable material cost and the copper busbar bonding cost is used as the reference cost. A relationship between the reference cost, cable length, and the number of bonding bolts is established. Based on this, with the goal of minimizing the reference cost, cable length and the number of bonding bolts can be adjusted while also taking the reference cost into account, thereby achieving dual optimization of the current deviation rate and line cost.

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

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

[0032] 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.

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

[0034] S31-1: Obtain the cable cross-sectional area, cable resistivity, copper busbar length, copper busbar cross-sectional area, copper busbar resistivity, lap bolt contact resistance, initial cable length, and initial number of lap bolts for each circuit and input them into the line resistance calculation model to obtain the initial line resistance of each circuit. Calculate the initial short-circuit current of all circuits based on the circuit voltage.

[0035] S31-2: Traverse all loops and arbitrarily select a loop as a reference loop. The corresponding initial short-circuit current is the reference current.

[0036] Step S32: Based on the initial line resistance and the reference current, adjust the cable length and the number of lap bolts of each loop so that the current deviation rate of each loop is less than 5%, and obtain multiple groups of adjustment results and the reference cost corresponding to each group of adjustment results; the adjustment results include the adjusted cable length and the number of lap 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, adjust the cable length and the number of lap bolts with the constraints that the loop length is not less than the corresponding minimum loop distance and the number of lap bolts is not less than the minimum number of lap bolts.

[0039] The minimum loop distance is set based on the distance that can connect the two devices corresponding to the loop and still have the specified cable margin (for example, a 15cm cable margin is reserved); the minimum number of lap bolts is set based on the number that meets the requirements for safe lap joints of copper busbars (for example, at least 5 bolts per lap joint).

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

[0041] Calculate the difference between the initial line resistance of each loop and the line resistance of the reference loop to determine the corresponding resistance adjustment amount for the loop:

[0042] ;

[0043] in, represents the resistance adjustment of the i-th loop; Indicates the line resistance of the reference loop; represents the initial line resistance of the i-th loop.

[0044] Calculate the cable length adjustment and bolt quantity adjustment for each circuit based on the resistance adjustment:

[0045] ;

[0046] in, represents the cable length adjustment of the i-th loop; Indicates the cable adjustment factor (used to control the adjustment range of cable length, which can be adjusted by the user according to actual needs);

[0047] ;

[0048] in, represents the adjustment amount of the number of bolts in the i-th circuit; Indicates the bolt adjustment coefficient (used to control the adjustment range of the bolt quantity, which can be adjusted by the user according to actual needs).

[0049] For each loop except the reference loop, with the goal of minimizing the reference cost, the cable length is adjusted based on the cable length adjustment amount, and the number of overlapping bolts is adjusted based on the bolt number adjustment amount 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 is reduced based on the corresponding cable length adjustment amount. If the cable length cannot be reduced any further (that is, further reduction of the cable length can no longer satisfy the constraint that the loop length is not less than the corresponding minimum distance of the loop), the number of lap 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 lap 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 entire step S32-1, the cable length adjustment amount and the bolt quantity adjustment amount are set specifically according to the line resistance difference of each loop compared with the reference loop, which is used for cable adjustment of the corresponding loop and adjustment of the number of overlapping bolts, so as to achieve more refined adjustment and further improve the current balancing effect of multiple loops.

[0052] S32-2: When all loops except the reference loop are adjusted, calculate the reference deviation rate of the adjusted short-circuit current of each loop compared with the reference current. If there is a loop with a reference deviation rate not less than 5%, return to step S32-1 for the loop until the reference deviation rate is less than 5%.

[0053] S32-3: Calculate the current deviation rate of all loops after adjustment based on the line resistance calculation model and formula 1. If there is a loop with a current deviation rate of not less than 5%, return to step S32-1 and execute until the current deviation rate is less than 5%. Record the current cable length and number of lap bolts of each loop.

[0054] Formula 1:

[0055] ;

[0056] in, represents the short-circuit current of the i-th circuit; Indicates the circuit voltage; Indicates the average short-circuit current of all circuits; Represents the current deviation rate of the i-th loop.

[0057] S32-4: Calculate the current reference cost based on the cable length and number of lap bolts of each current loop, and return to execute step S31-2 until all loops have been adjusted as reference loops to obtain multiple reference costs.

[0058] Step S33: Determine the minimum reference cost from the multiple reference costs, take the cable length of each loop corresponding to the minimum reference cost as the optimal cable length, and take the number of lap bolts of each loop corresponding to the minimum reference cost as the optimal number of lap bolts.

[0059] In the entire step S3, all loops are traversed through a multi-layer nested loop structure, and each loop is used as a reference loop. By adjusting the cable length and the number of lap bolts of each loop, the difference in line resistance of each loop compared with the reference loop is optimized. Multiple optimization results can be obtained for comparing implementation costs and determining the best optimization result, thereby avoiding missing the best optimization result and further reducing the implementation cost of multi-loop current balancing.

[0060] Step S4: Calculate the actual current deviation rate of each circuit based on the actual current of each circuit under the conditions of optimal cable length and optimal number of lap bolts. If the actual current deviation rate is not less than 5%, return to step S3 and execute until the actual current deviation rate is less than 5%, completing current balancing.

[0061] In this embodiment, by establishing a line resistance calculation model and establishing an objective function based on cable material cost and lap cost, and using an optimization algorithm to adjust the cable length and number of lap bolts for each circuit under the condition that the current deviation rate is less than 5%, the line resistance of each circuit can be accurately controlled. This minimizes the cost while reducing the difference in line resistance of each circuit to within the required range, thereby achieving current balancing for multiple circuits. Therefore, the present invention can significantly reduce implementation costs while achieving multi-circuit current balancing.

[0062] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0063] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A multi-circuit current balancing method, characterized in that: The loop length difference between the multiple loops is less than 1 meter, and the method comprises the following steps: S1, establish a line resistance calculation model based on the number of lap bolts, cable length, cable cross-sectional area, cable resistivity, copper busbar length, copper busbar cross-sectional area, copper busbar resistivity, and lap bolt contact resistance: ； in, represents the line resistance of the i-th loop; Indicates the length of the copper busbar of the i-th circuit; represents the cable length of the i-th loop; Indicates the cross-sectional area of ​​the cable; Indicates the cable resistivity; Indicates the resistivity of copper busbar; Indicates the cross-sectional area of ​​the copper busbar; represents the number of lap bolts in the i-th circuit; Represents the contact resistance of a single lap bolt; S2, with the lowest reference cost as the goal, establishes the objective function based on the cable material cost and copper busbar bonding cost: ； in, represents the lowest reference cost; Indicates the cable material cost per unit volume; Indicates the lap bolt spacing; Indicates the width of the overlapping copper busbar; Indicates the thickness of the overlapping copper busbar; Indicates copper density; Indicates the unit price of copper; S3, based on the objective function and the line resistance calculation model, adjusting the cable length and the number of overlapping bolts of each loop until the current deviation rate of each loop is less than 5%, thereby obtaining the optimal cable length and the optimal number of overlapping bolts for each loop; S4, calculate the actual current deviation rate of each circuit based on the actual current of each circuit under the conditions of optimal cable length and optimal number of lap bolts. If the actual current deviation rate is not less than 5%, return to step S3 and execute until the actual current deviation rate is less than 5%, completing current balancing.

2. The multi-circuit current balancing method according to claim 1, wherein: The S3 specifically includes: Step S31, calculating the initial line resistance and initial short-circuit current of each loop based on the line resistance calculation model, and determining a reference current; Step S32: Based on the initial line resistance and the reference current, adjust the cable length and the number of lap bolts of each loop so that the current deviation rate of each loop is less than 5%, and obtain multiple sets of adjustment results and reference costs corresponding to each set of adjustment results; the adjustment results include the adjusted cable length and number of lap bolts of each loop; Step S33: Determine the minimum reference cost from the multiple reference costs, take the cable length of each loop corresponding to the minimum reference cost as the optimal cable length, and take the number of lap bolts of each loop corresponding to the minimum reference cost as the optimal number of lap bolts.

3. The multi-circuit current balancing method according to claim 2, wherein: The S31 specifically includes: S31-1, obtaining the cable cross-sectional area, cable resistivity, copper busbar length, copper busbar cross-sectional area, copper busbar resistivity, lap bolt contact resistance, initial cable length, and initial number of lap bolts for each circuit, inputting these into a line resistance calculation model to obtain the initial line resistance of each circuit, and calculating the initial short-circuit current of all circuits based on the circuit voltage; S31-2, traverse all loops, arbitrarily select a loop as a reference loop, and the corresponding initial short-circuit current is the reference current.

4. The multi-circuit current balancing method according to claim 3, wherein: The S32 specifically includes: S32-1, for all loops except the reference loop, based on the objective function and the initial line resistance, with the loop length not less than the corresponding minimum loop distance and the number of lap bolts not less than the minimum number of lap bolts as constraints, adjust the cable length and the number of lap bolts; S32-2, when all loops except the reference loop are adjusted, calculate the reference deviation rate of the adjusted short-circuit current of each loop compared to the reference current. If the reference deviation rate of any loop is not less than 5%, return to step S32-1 for that loop until the reference deviation rate is less than 5%; S32-3, calculate the adjusted current deviation rate of all loops based on the line resistance calculation model and Formula 1. If the current deviation rate of any loop is not less than 5%, return to step S32-1 and continue until the current deviation rate is less than 5%. Record the current cable length and number of lap bolts for each loop. S32-4, calculate the current reference cost based on the cable length and the number of lap bolts of each current loop, and return to execute step S31-2 until all loops have been adjusted as reference loops to obtain multiple reference costs.

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