The National Energy Administration recently issued a notice on ensuring the high-quality development of new energy by doing a good job in the consumption of new energy. The notice puts forward specific requirements for key areas of concern and urgent improvement, such as coordinated development of power sources, improvement of regulation capabilities, allocation of power grid resources, and optimization of new energy utilization targets. The notice aims to plan and construct a new energy system, achieveThe 'dual carbon' target is of great significance.

Regarding the policy of promoting on-site consumption of distributed photovoltaics and not allowing grid connection, anti backflow management needs to be set up for newly installed distributed photovoltaics. Where should we monitor it?

The grid connection point of a distributed photovoltaic power generation system refers to the connection point between the distributed photovoltaic power generation system and the power grid, which may be a public power grid or a user power grid.

I believe many friends confuse photovoltaic grid connection points. Below, we will use a picture to explain it clearly to everyone

As shown in the figure, the dashed box represents the user's power grid, which is connected through a common connection pointCConnected to the power grid. Within the user's power grid, there are two distributed photovoltaic power generation systems, each of which utilizesAPoint andBThe point is connected to the user's power grid,APoint andBAll points are connection points, but not public connection points. inDDistributed photovoltaic power generation systems are directly connected to the public power grid,DA point is a branch point and also a public connection point.

Therefore, the anti backflow of distributed photovoltaics should monitor the grid power at the common connection point.

Ankerui distributed photovoltaic monitoring systemAcrel-1000DPCombined with anti backflow protection deviceAM5SE-ISIt can monitor the power consumption of the grid in real time, and set anti backflow control strategies in the software to meet the requirements of anti backflow grid connection at the site. The anti backflow protection device is equipped with reverse power protection function for dual protection.

according to GB/T 50865”When the photovoltaic power generation system is designed for irreversible grid connection, reverse power protection equipment should be configured. When the reverse current is detected to exceed the rated output5%At that time, the photovoltaic power generation system should2sAutomatically reduce output or stop supplying power to the grid lines. ”

There are currently anti backflow protection devices available2The selection can be based on the application scenario.

1）When the distance between the grid connection point and the backflow detection point is close, chooseAM5SE-ISAnti backflow protection device.

Anti backflow protection deviceAM5SE-IS

AM5SE-ISAnti backflow protection device, equipped with:

Reverse power tripping, reverse power restoration closing;

Low power tripping, low power recovery closing.

The figure below showsAM5SE-ISFunctional diagram of anti backflow protection device:

2）When the distance between the grid connection point and the backflow detection point is far（200rice~2Within a kilometer range, it is necessary to use a master-slave scheme to achieve reverse power protection, that is, by installing a reverse current protection host at the mains power inlet and a reverse current protection slave at the grid connection point, the two are connected through optical fiber. When the host detects reverse power, it sends commands to the slave through the optical fiber, and the slave jumps off the grid cabinet. choiceAM5SE-PVSeries master-slave anti backflow protection device.

AM5SE-PVSeries anti backflow protection device, equipped with:

Master slave scheme with four stages of low power/Low power restoration closing

Reverse power of master-slave scheme/Reverse power recovery closing

Host anti islanding protection

Anti islanding protection from aircraft.

The figure below showsAM5SE-PVFunctional diagram of anti backflow protection device for master-slave scheme:

If there are multiple grid connection points for the incoming power line, the host should be selectedAM5SE-PVMSelection of slave machinesAM5SE-PVS（*More support1main5From).

Note: The distance issue mentioned above is related to the capacity of the current transformer and the cross-sectional area of the wiring cable, and can be comprehensively considered based on the following empirical values: