1Current situation of user side grid connected power generation system

With the development of new energy, many users will choose to install distributed photovoltaic power generation, wind power generation, energy storage and other power generation systems on the basis of the existing public power grid distribution system. However, due to fluctuations in power generation and continuous changes in user side electricity load, in order to prevent reverse power generation from the user side grid connected power generation system and reverse power transmission to the public grid, it is necessary to scientifically and reasonably use the user side grid connected power generation system, and at the same time, perform safety control on the user side grid connected power generation system to achieve anti backflow function.

2Anti backflow solution for user side grid connected power generation system

pressGB/T 50865-2013《photovoltaic power generationConnect to the distribution networkDesign specifications》In the middle6.3.2Regulation: "When the photovoltaic power generation system is designed for irreversible grid connection, reverse power protection equipment should be configured. When the reverse current exceeds the rated output5%At that time, the photovoltaic power generation system should2sAutomatically reduce output or stop supplying power to the grid lines. ”

pressGB/T 43526-2023 《Technical regulations for connecting user side electrochemical energy storage systems to distribution networks》In the middle10.7Regulation: "For user side electrochemical energy storage systems that do not allow reverse power transmission to the grid, the common connection point should have reverse power protection function

2.1 Design standards and basis

GB/T 19964-2024 《Technical Regulations for Connecting Photovoltaic Power Stations to Power Systems

How to translate GB/T 29319-2024《

Technical Regulations for Connecting Photovoltaic Power Generation Systems to Distribution Networks How to translate

GB/T 50865-2013 《

Design Specification for Photovoltaic Power Generation Connected to Distribution NetworkHow to translate

GB/T 43526-2023Technical Regulations for Connecting User Side Electrochemical Energy Storage Systems to Distribution NetworksGB /

T 31366-2015Technical Requirements for Photovoltaic Power Station Monitoring SystemGB /T 50052-2009Design Specification for Power Supply and Distribution System

GB / T

50053-2013 《 Design Specification for 20kV and Below Substations

GB/T50062-2008Design Specification for Relay Protection and Automatic Devices of Power Equipment GB/T

50063-2017Design Specification for Electrical Measuring Instruments of Power EquipmentGB /

2.2 T 19939-2005

Technical Requirements for Grid Connection of Photovoltaic SystemsGB/T 31366-2015Technical Requirements for Photovoltaic Power Station Monitoring SystemAnti backflow solution for user side grid connected power generation systemAdopting a method that does not allow reverse power transmission to the gridWhen the user side is connected to the grid for power generation,

Need to configure at the public connection point

Anti backflow protection device，By combining the flexible adjustment of anti backflow software and the rigid tripping of anti backflow protection, the grid connected cabinet can be quickly disconnected when reverse power is generated and transmitted to the public grid,Prevent the continuous generation of electricity by the user side grid connected power generation system from being transmitted back to the public grid

.The configuration schemes for anti backflow protection devices in different application scenarios are as follows:1)When the backflow monitoring point and

Cable laying distance between grid connected cabinetsWithin 100 meters, the AM5SE-IS standalone device is used to achieve anti backflow protection function;

2)When the backflow monitoring point andThe distance of cable laying between grid connected cabinets isWhen the distance is between 100 meters and 40 kilometers, the AM5SE-PV series master-slave device is used, and fiber optic connections can be used between the master and slave devices to achieve remote anti backflow function.1system topologyUser side grid connected power generation systemAccording to the three-layer architecture design of station control layer, interval layer, and equipment layer, real-time data collection is carried out through the interval layer communication management machine and network switch

Anti backflow protection deviceData from secondary equipment such as microcomputer protection devices, power quality monitoring, metering, and remote control systems to achieve multiple areasUser side grid connected power generation system

Comprehensive monitoring and automated management. At the same time, a communication system, a timing system, and a remote control system are configured in the monitoring room to meet the internal communication and higher-level scheduling needs of the system. An integrated power supply system is configured to provide stable and reliable power for the operation of important equipment such as secondary equipment and monitoring hosts, achieving the entire system

User side grid connected power generation system

4.1 Safe and stable operation.

1

4.2 Anti backflow soft

Item FunctionThe anti backflow software can monitor the power changes of anti backflow monitoring points in real time, including the current total power of photovoltaic power generation, real-time discharge power and charging power of energy storage, as well as the real-time power of each grid connected unit and grid connection point.

4.3 The anti backflow software can set the power threshold and tripping action time for reverse power tripping, the power threshold and adjustment time for low-power regulation, and the power value and restoration closing action time for judging the closing after the power returns to normal.

Low power flexible adjustmentThe anti backflow software sets a power threshold for low-power regulation (which is the off grid power used by the user side on the public grid). When the off grid power of the public grid is low and reverse power may occur due to load fluctuations, the anti backflow software flexibly adjusts and sends a command to reduce the power generation to the grid connected units of the user side parallel power generation system to prevent reverse power generation.

Reverse power tripThe anti backflow software sets the power threshold for reverse power tripping (which is the grid connected power supplied by the user side grid connected power generation system in reverse to the public grid). When the grid connected power supplied by the user side grid connected power generation system in reverse to the public grid triggers the reverse power tripping power threshold, the anti backflow software sends a tripping instruction to the grid connected unit of the user side grid connected power generation system, cutting off the grid connected unit of the user side grid connected power generation system and preventing continuous reverse power supply to the public grid

5.1.

Power restoration closingWhen the grid connected unit of the user side grid connected power generation system trips due to reverse power, and the user side uses the off grid power of the public grid to restore the normal threshold, and the grid connected unit still fails to close within the power restoration closing time, the anti backflow software sends a closing instruction to the grid connected unit of the tripped user side grid connected power generation system to restore the power generation of the grid connected unit of the user side grid connected power generation system, improve the utilization rate of the user side grid connected power generation system, and reduce the use of the public grid.1

Anti backflow protection deviceSingle machine version anti backflow protection deviceAM5SE-ISbackflow preventionprotective deviceAM5SE-ISpreventagainst the currentThe protective device is mainly suitable for35kVThe10kVAnd low voltage380VPhotovoltaic power generationwind powerpower generationEnergy storage charging and dischargingWaiting for the new energy grid connected power supply system. when

5.2 Reverse power supply to the public power grid

When the phenomenon occurs, the grid connection point can be quickly cut off to makeThis site does not continuously supply power in reverse to the power grid

Ensure the power stationThe use meets the requirements of the power grid.

Master slave version anti backflow protection device5.2.1Fiber optic direct jump schemeAM5SE-PVSeries anti backflow protection device

AM5SE-PVThe master-slave of the series anti backflow protection device is connected by optical fiber,passFiber optic link

Remote input and output to prevent backflow.1)When the backflow monitoring point and

The cable laying distance between the grid cabinets of the user side grid connected power generation system grid connected units isAM5SE-PV series master-slave scheme can be used between 100 meters and 1.5 kM, and multi-mode fiber optic 62.5/125 μ m, wavelength 850 nm, ST interface connection can be used between the master and slave;2)When the backflow monitoring point and

5.2 The cable laying distance between the grid cabinets of the user side grid connected power generation system grid connected units isThe AM5SE-PV series master-slave scheme can be used between 1.5kM and 20km, and single-mode fiber with a wavelength of 1310nm and ST interface connection can be used between the master and slave;

3)When the backflow monitoring point andThe cable laying distance between the grid cabinets of the user side grid connected power generation system grid connected units is

The AM5SE-PV series master-slave scheme can be used between 20km and 40km, and single-mode fiber with a wavelength of 1550nm and ST interface can be used between the master and slave.. 2 GOOSEcommunication schemeAM5SE-PVSeries anti backflow protection deviceAM5SE-PVThe master-slave of the series anti backflow protection device is connected by optical fiber,

passFiber optic link groupGOOSEcommunication network

Implement anti backflow measures.1)When the backflow monitoring point and