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UPS parallel function and method, and the application of parallel technology in UPS system

2020-10-30
UPS parallel function and method, and the application of parallel technology in UPS system. At present, many companies have not selected the best connection method according to the actual situation in the process of choosing the UPS connection method, which has caused the whole system to have large or small risks in the operation process. This article introduces the parallel function and method and the application of parallel technology in the UPS system, hoping to play a certain role in reducing enterprise operating costs.

UPS parallel mode

UPS paralleling means that when two or more UPSs are working at the same time, the related loads are dispersed, and the responsibility is small, which naturally reduces the probability of failure. This is because when a machine fails, other intact power supplies will assume the responsibility of the failed power supply, and the operation of the entire system will not be affected in a short time. Master-slave hot-standby, mutual assistance, and interactive hot-standby are the three main ways of UPS paralleling. The three of them often play different roles and have different advantages in work due to different line connection methods and working methods. , When choosing, we must carefully consider the characteristics of the equipment.

The advantages of master-slave hot-standby UPS parallel are high flexibility, simple installation, and no need to add additional auxiliary circuits. There is no big difference between this parallel mode and UPS series connection, and the shortcomings are the same as those in series connection. That is, the main machine is loaded during normal use and the standby machine is unloaded, resulting in inconsistent aging of the two machines and low instantaneous overload capacity. The advantage of mutual-assisted redundant parallel UPS parallel is that it can automatically share the load, has a strong instantaneous overload capacity, and does not have the problem of uneven aging. Mutual-assisted redundant parallel UPS parallel has 4 power supply lines (mains 1, mains 2, bypass and battery). The two UPSs work with 50% load under normal conditions. If one of the UPS fails, it will be disconnected immediately System, the load is automatically switched to another UPS.

When a single machine fails, the load of the UPS that works normally increases from 50% to 100%. Compared with the master-slave hot standby type from 0% to 100%, the load change is small, so the system has a strong overload capacity and ensures the output stability. The interactive hot-standby UPS has dual outputs in parallel, and the two UPSs serve as backups for each other, but need to share the load manually. When the load distribution is reasonable, its instantaneous overload capacity is very strong.

The advantages and disadvantages of the four ways of UPS parallel

1, master-slave hot backup
The host is loaded, the standby machine is unloaded, and the standby machine is connected to the BYPASS input of the host

advantage:
●High flexibility, not restricted by brand
●Simple installation, no need for additional debugging
●No additional auxiliary circuit, no increase in purchase cost
●It can be used as n+1 hot backup and can be expanded in stages

Disadvantages:
●Low instantaneous overload capacity
●Inconsistent aging of the two machines
●The standby battery is not in the floating state for a long time, which affects the battery life

2. Interactive hot backup
The two machines are loaded separately, and the load is distributed manually in advance. It is an improved type of master-slave hot backup

advantage:
●This scheme is an improved type of master-slave hot backup, and is a parallel scheme that distributes the load at a time. In addition to retaining the advantages of master-slave hot backup, all its disadvantages are overcome
●Strong instantaneous overload capability
●There is no long-term floating charge state of the backup battery
●There is no Achilles heel of the redundant parallel scheme-circulation
Disadvantages:
If the load power cannot be distributed manually, this scheme is not applicable

Three, interactive hot backup (ATS)

Single machine with load, unit interaction

advantage:
●Due to the use of unit interaction, the probability of system failure is greatly reduced
●Two UPSs can work in rotation
●No bottleneck failure point

Disadvantages:
●Low instantaneous overload capacity

Fourth, redundant parallel (N+X)
Automatically share the load. The development process from parallel cabinets, parallel modules, parallel boards, wireless parallel to digital control, automatic parallel (parallel UPS adopts current control for equal distribution and complete independent control)

advantage:
●Strong instantaneous overload capability
●No bottleneck failure point
●Automatic power sharing

Disadvantages:
●There are circulating currents, and different paralleling methods have different circulating currents. Circulating current increases reactive power loss and reduces system reliability
●No matter what kind of parallel scheme, additional auxiliary circuits are required, which will increase the cost and the point of failure

In short, the parallel use of UPS has become a new model emerging in the development of many companies. It plays an important role in ensuring system stability, extending equipment life and improving corporate economic benefits. According to the different power supply equipment and power supply mode, the reasonable choice of parallel mode should be a matter of careful consideration by the enterprise.



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