Control method and control system of multi-machine parallel hydrogen production power supply

Abstract

The invention relates to a control method and a control system for a multi-machine parallel hydrogen production power supply, and belongs to the technical field of power supplies. The method comprises the following steps: calculating the total number of chopping branches of all the multi-machine parallel hydrogen production power supplies, and sorting the chopping branches of all the multi-machine parallel hydrogen production power supplies; according to the total number of the chopping branches and the switching period, calculating the phase difference when all the chopping branches are interleaved and connected in parallel, calculating the phase difference of the chopping branch relative to the first chopping branch according to the serial number of the corresponding chopping branch, and performing corresponding phase shift on carriers of the chopping branches of all the multi-machine parallel hydrogen production power supplies. The invention is used for solving the problem that the total number of interleaved chopping branches is not fully utilized and the ripples are relatively large because chopping waves of all power units are not uniformly sorted to equally divide one switching period, but chopping branches in each power unit equally divide one switching period.

Description

Technical Field

[0001] The invention relates to a control method and a control system for a multi-machine parallel hydrogen production power supply, belonging to the technical field of power supplies. Background Art

[0002] With the development of electrolyzers, alkaline electrolyzers have reached specifications of thousands of cubic meters, and the capacity of the hydrogen production power supply that matches them has also reached the MW level. High-power IGBT-type hydrogen production power supplies often adopt a multi-machine parallel solution, which can be flexibly configured to adapt to electrolyzers of different specifications. The multi-machine parallel hydrogen production power supply consists of multiple power units connected in parallel with AC and DC. The chopped output of each power unit is connected in parallel to the electrolyzer. The chopper branch inside the power unit uses a multi-branch staggered method to reduce the output ripple, which can achieve low ripple output while reducing the filter inductance. When a power unit fails, the system can operate redundantly to maintain the normal operation of the electrolyzer.

[0003] In order to simplify and facilitate control, most existing technical solutions do not uniformly sort the choppers of all power units to evenly divide a switching cycle. Instead, the chopper branches within each power unit evenly divide a switching cycle, so that the total number of chopper branches staggered in parallel is not fully utilized, resulting in a large ripple problem. Summary of the invention

[0004] The purpose of the present invention is to provide a control method and control system for a multi-machine parallel hydrogen production power supply, so as to solve the problem of large ripple caused by not uniformly arranging the choppers of all power units to evenly divide a switching cycle, but evenly dividing a switching cycle among the chopper branches inside each power unit, so that the total number of chopper branches staggered in parallel is not fully utilized.

[0005] To achieve the above object, the solution of the present invention includes:

[0006] A control method for a multi-machine parallel hydrogen production power supply of the present invention calculates the total number of chopping branches of all the multi-machine parallel hydrogen production power supplies and sorts the chopping branches of all the multi-machine parallel hydrogen production power supplies; calculates the adjacent phase difference between two adjacent chopping branches when all the chopping branches are staggered in parallel according to the total number of chopping branches and the switching cycle, and then calculates the relative phase difference of the chopping branch relative to the first chopping branch according to the sequence number of the corresponding chopping branch, and performs corresponding phase shifting on the carrier of the chopping branch of all the multi-machine parallel hydrogen production power supplies according to the relative phase difference of the carrier branch.

[0007] Furthermore, the total number of chopping branches of all multi-machine parallel hydrogen production power supplies is the number of all power units multiplied by the number of chopping branches of each power unit.

[0008] Furthermore, the sequence number k of the chopping branch branch Calculated by the following formula:

[0009] k branch =(N unit_num -1)*N brance +N branch_num

[0010] Among them, N unit_num is the number of the power unit where the chopper branch whose number is to be calculated is located, N branch The number of chopper branches for each power unit, N branch_num is the serial number of the chopper branch whose serial number is to be calculated in the power unit where it is located.

[0011] Furthermore, when all chopping branches are staggered in parallel, the adjacent phase difference between two adjacent chopping branches is Calculated by the following formula:

[0012]

[0013] Where T is the switching period, N branch_total It is the total number of chopping branches of multi-machine parallel hydrogen production power supply.

[0014] Furthermore, the relative phase difference θ k_branch Calculated by the following formula:

[0015]

[0016] in, is the adjacent phase difference, k branch is the sequence number of the chopping branch.

[0017] Furthermore, when a power unit fails, the failed power unit exits operation, and the total number of chopping branches is recalculated and sorted.

[0018] Furthermore, when a power unit fails, the failed power unit stops running, normal power units are reordered, and the sequence numbers of the chopping branches are reordered.

[0019] Furthermore, the steps of normal power unit reordering are as follows: 1) Determine whether the sequence number i of the i-th power unit is less than or equal to the total number of power units N unit ; 2) If yes, continue to determine whether the i-th power unit is normal; 3) If normal, reorder the i-th power unit according to the number of currently normal power units, and increment i by 1; if abnormal, increment i by 1; repeat steps 1) to 3) until the power unit number i is greater than the total number of power units N unit .

[0020] Furthermore, a control system for a multi-machine parallel hydrogen production power supply includes a central controller and a power unit controller. The central controller is used to calculate the total number of chopping branches of all multi-machine parallel hydrogen production power supplies and sort the chopping branches of all multi-machine parallel hydrogen production power supplies, and also calculate the adjacent phase difference between two adjacent chopping branches when all chopping branches are staggered in parallel according to the total number of chopping branches and the switching cycle, and send the adjacent phase difference to each power unit controller accordingly; the power unit controller is used to calculate the relative phase difference of the chopping branch relative to the first chopping branch according to the sequence number of the corresponding chopping branch and the adjacent phase difference, and perform corresponding phase shifting on the carrier of the chopping branch of all multi-machine parallel hydrogen production power supplies according to the relative phase difference of the carrier branch.

[0021] Furthermore, when a power unit fails, the failed power unit exits operation, and the total number of chopping branches is recalculated and sorted.

[0022] The beneficial effects of the present invention are as follows: the present invention provides a control method and control system for a multi-machine parallel hydrogen production power supply, calculates the total number of chopping branches of all multi-machine parallel hydrogen production power supplies and sorts the chopping branches of all multi-machine parallel hydrogen production power supplies; calculates the phase difference when all chopping branches are staggered in parallel according to the total number of chopping branches and the switching cycle, and also calculates the phase difference of the chopping branch relative to the first chopping branch according to the sequence number of the corresponding chopping branch, and performs corresponding phase shifting on the carrier of the chopping branch of all multi-machine parallel hydrogen production power supplies. The problem of large ripples caused by not uniformly sorting the chopping of all power units to evenly divide a switching cycle, but evenly dividing a switching cycle in each power unit, so that the total number of chopping branches staggered in parallel is not fully utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the circuit topology diagram of multi-machine parallel hydrogen production power supply;

[0024] Figure 2 It is a schematic diagram of the control system of a multi-machine parallel hydrogen production power supply;

[0025] Figure 3 It is the system redundant operation control flow chart. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail in a clear and complete manner in conjunction with the accompanying drawings and embodiments.

[0027] The idea of ​​the present invention is to uniformly sort the choppers of all power units to evenly divide a switching cycle, so that all chopper branches are staggered at a smaller angle, achieving a smaller ripple output, thereby further reducing the filter inductance in hardware design.

[0028] like Figure 1 The figure shows the circuit topology of a multi-machine parallel hydrogen production power supply. The multi-machine parallel hydrogen production power supply consists of multiple power units connected in parallel in AC and DC. The power unit is an IGBT type, consisting of a rectifier side and a chopper side. The rectifier side converts the AC voltage into a DC voltage to provide a stable DC source for the chopper side. The chopper side responds to the system's instructions to provide the required current to the electrolyzer.

[0029] like Figure 2 The figure shows a control system diagram of a multi-machine parallel hydrogen production power supply. The multi-machine parallel hydrogen production power supply adopts a control system solution of a central controller + power unit controller. The central controller is responsible for the system's start and stop logic, protection logic, power distribution, redundant phase shift strategy, external interaction, etc. The power unit controller is responsible for output voltage, current, power control, adaptive phase shift, AC harmonic suppression, power factor control, reactive power control, etc.

[0030] Method Example:

[0031] 1. System normal operation control method:

[0032] (1) Calculate the total number of chopping branches of the hydrogen production power supply:

[0033] If the high-power hydrogen production power source is N unit The chopping side of each power unit consists of N branch The total number of hydrogen production power chopper branches is N branch_total for:

[0034] N brsnch_total =N unit *N branch (1.1)

[0035] (2) Number the chopping branches:

[0036] First, number the power units in sequence (the power unit numbers are 1, 2, 3, ..., N unit ), and then number the chopping branches in sequence according to the number of the power unit. For example, the chopping branches of power unit 1 are numbered 1, 2, 3, ..., N in sequence. branch The chopper branches of power unit 2 are numbered following the chopper branches of power unit 1, and the overall order of the chopper branches is 1, 2, 3, ..., N. branch , N branch +1, N branch +2, N branch +3,…,2*N btanch , …,

[0037] (N unit -1)*N branch +1,(N unit -1)*Nbranch +2, (N unit -1)*N branch +3, …,

[0038] (N unit -1)*N branch +N branch .

[0039] Finally, according to the above rules, the chopping branch number can be obtained as:

[0040] k branch =(N unit_num -1)*N branch +N branch_num (2.1)

[0041] N unit_num The number of the power unit where the chopper branch whose number is to be calculated is located 1, 2, 3, ..., N unit

[0042] N branch_num The number of the chopper branch to be calculated in the power unit is 1, 2, 3, ..., N branch

[0043] (3) Calculate the phase difference of the chopper branch:

[0044] Assuming that the switching period of the chopping branch is T, the adjacent phase difference between two adjacent chopping branches when the chopping branches are staggered in parallel is:

[0045]

[0046] Taking the zero crossing point of the carrier of chopping branch 1 as the reference, the relative phase difference of the carriers of other chopping branches relative to chopping branch 1 is:

[0047]

[0048] In actual operation, the central controller first calculates the adjacent phase difference between the chopper branches using formula (3.1): And it is sent to each power unit controller. The power unit controller calculates the relative phase of each chopping branch lagging behind the chopping branch 1 according to its own unit number and the chopping branch sequence number through formula (2.1) (3.2), and shifts the carrier of the chopping branch accordingly, so as to evenly divide the time of a switching cycle and reduce the output ripple.

[0049] 2. System Redundancy Operation Control Method:

[0050] If a power unit fails, the system will operate redundantly, the failed power unit will exit operation, and the normal power units will be reordered and staggered according to the new phase difference to ensure the normal operation of the electrolyzer.

[0051] Specific control process such as Figure 3 As shown, the steps of reordering normal power units are as follows: 1) Determine whether the sequence number i of the i-th power unit is less than or equal to the total number of power units N unit ; 2) If yes, continue to determine whether the i-th power unit is normal; 3) If normal, reorder the i-th power unit according to the number of currently normal power units, and increment i by 1; if abnormal, increment i by 1; repeat steps 1) to 3) until the power unit number i is greater than the total number of power units N unit .

[0052] For example, first determine whether the first power unit i=1 is less than or equal to the total number of units N unit , obviously N unit >1, so continue to judge whether the power unit i=1 is normal. If it is judged that the power unit i=1 is normal, the re-ordered number of the first power unit i is j=1; then i is incremented by 1, and continue to judge whether the second power unit is normal. If the second power unit is normal, the number of the second power unit i=2 is j=2; if the second power unit is abnormal, i is incremented by 1, and continue to judge whether the third power unit is normal, until all normal power units are judged and numbered.

[0053] When a power unit fails, the power unit controller will reset the power unit according to the new number and new phase difference. Recalculate the phase difference θ relative to chopper branch 1 k_branch_new , and finally the time of a switching cycle is evenly divided, avoiding the problem of increased ripple due to uneven phase difference.

[0054] System Example:

[0055] A control system for a multi-machine parallel hydrogen production power supply of the present invention includes a central controller and a power unit controller, the central controller is used to calculate the total number of chopping branches of all multi-machine parallel hydrogen production power supplies and sort the chopping branches of all multi-machine parallel hydrogen production power supplies, calculate the adjacent phase difference between two adjacent chopping branches when all chopping branches are staggered in parallel according to the total number of chopping branches and the switching cycle, and send the adjacent phase difference to each power unit controller accordingly; the power unit controller is used to calculate the relative phase difference of the chopping branch relative to the first chopping branch according to the sequence number and adjacent phase difference of the corresponding chopping branch, and perform corresponding phase shifting on the carrier of the chopping branch of all multi-machine parallel hydrogen production power supplies according to the relative phase difference of the carrier branch. This method has been introduced clearly enough in the method embodiment and will not be repeated here.

Claims

1. A control method for a multi-machine parallel hydrogen production power supply, characterized in that: The total number of chopping branches of all multi-machine parallel hydrogen production power supplies is calculated and the chopping branches of all multi-machine parallel hydrogen production power supplies are sorted; the adjacent phase difference between two adjacent chopping branches when all chopping branches are staggered in parallel is calculated according to the total number of chopping branches and the switching period, and then the relative phase difference of the chopping branch relative to the first chopping branch is calculated according to the sequence number of the corresponding chopping branch, and the carrier of the chopping branch of all multi-machine parallel hydrogen production power supplies is phase-shifted accordingly according to the relative phase difference of the carrier branch.

2. The control method of a multi-machine parallel hydrogen production power supply according to claim 1, characterized in that: The total number of chopping branches of all multi-machine parallel hydrogen production power supplies is the number of all power units multiplied by the number of chopping branches of each power unit.

3. The control method of a multi-machine parallel hydrogen production power supply according to claim 1, characterized in that: The sequence number k of the chopping branch branch Calculated by the following formula: k branch =(N unit_num -1)*N branch +N branch_num Among them, N unit_num is the number of the power unit where the chopper branch whose number is to be calculated is located, N branch The number of chopper branches for each power unit, N branch_unm is the serial number of the chopper branch whose serial number is to be calculated in the power unit where it is located.

4. The control method of a multi-machine parallel hydrogen production power supply according to claim 1, characterized in that: When all the chopping branches are staggered in parallel, the adjacent phase difference between two adjacent chopping branches is Calculated by the following formula: Where T is the switching period, N branch_total It is the total number of chopping branches of multi-machine parallel hydrogen production power supply.

5. The control method of a multi-machine parallel hydrogen production power supply according to claim 1, characterized in that: The relative phase difference θ k_branch Calculated by the following formula: in, is the adjacent phase difference, k branch is the sequence number of the chopping branch.

6. The control method of a multi-machine parallel hydrogen production power supply according to claim 1, characterized in that: When a power unit fails, the failed power unit exits operation, and the total number of chopping branches is recalculated and sorted.

7. The control method of a multi-machine parallel hydrogen production power supply according to claim 3, characterized in that: When a power unit fails, the failed power unit stops running, normal power units are reordered, and the sequence numbers of the chopping branches are reordered.

8. The control method of a multi-machine parallel hydrogen production power supply according to claim 7, characterized in that: The steps of normal power unit reordering are as follows: 1) Determine whether the sequence number i of the i-th power unit is less than or equal to the total number of power units N ynit ; 2) If yes, continue to determine whether the i-th power unit is normal; 3) If normal, reorder the i-th power unit according to the number of currently normal power units, and increment i by 1; if abnormal, increment i by 1; repeat steps 1) to 3) until the power unit number i is greater than the total number of power units N ynit .

9. A control system for a multi-machine parallel hydrogen production power supply, comprising a central controller and a power unit controller, characterized in that: The central controller is used to calculate the total number of chopping branches of all multi-machine parallel hydrogen production power supplies and sort the chopping branches of all multi-machine parallel hydrogen production power supplies, and also calculate the adjacent phase difference between two adjacent chopping branches when all chopping branches are staggered in parallel according to the total number of chopping branches and the switching cycle, and send the adjacent phase difference to each power unit controller accordingly; the power unit controller is used to calculate the relative phase difference of the chopping branch relative to the first chopping branch according to the sequence number of the corresponding chopping branch and the adjacent phase difference, and perform corresponding phase shift on the carrier of the chopping branch of all multi-machine parallel hydrogen production power supplies according to the relative phase difference of the carrier branch.

10. The control system of multi-machine parallel hydrogen production power supply according to claim 9, characterized in that: When a power unit fails, the failed power unit exits operation, and the total number of chopping branches is recalculated and sorted.

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