What is the principle of communication and net cage?
Net cage is a key equipment in photovoltaic power generation systems, mainly used to achieve safe and stable connection between photovoltaic energy and the power grid. The core principle is to integrate multiple electrical components, coordinate the direction of electrical energy flow, ensure efficient operation of the system, and meet the requirements of the power grid.
Core working principle
The core function of grid connection is to monitor the real-time flow of electricity at the grid connection point and automatically control the flow of electricity based on load demand and power generation. The specific process is as follows:
Electricity conversion and monitoring: The direct current generated by photovoltaic modules is converted into alternating current by an inverter and enters the grid. The anti backflow protection device (or reverse power protection device) integrated inside the box will continuously monitor the current direction, voltage, and power value of the grid connection point.
Anti backflow control: When the photovoltaic power generation exceeds the local load demand, excess electricity may flow back to the grid. After the anti backflow device detects the backflow phenomenon (i.e. the reverse flow of current), it will immediately trigger the protection action, and cut off the connection between the photovoltaic system and the power grid by controlling the contactor or circuit breaker, thereby preventing surplus electricity from being connected to the grid. On the contrary, when the load demand exceeds the generated power, the system automatically supplements electrical energy from the grid, achieving "self use".
Security protection mechanism: The mesh cage also integrates multiple protection functions, such as short circuit protection, overload protection, leakage protection, surge protection, etc., to cope with power grid abnormalities (such as overvoltage, undervoltage, frequency deviation) or equipment failures, ensuring system and personnel safety.
Key components and functions
The net cage usually includes the following core components, which work together to achieve the above functions:
Grid connected switches and contactors: used for manual or automatic control of the connection and disconnection between photovoltaic systems and the power grid, facilitating maintenance and fault isolation.
Measurement and monitoring instruments: Real time display of voltage, current, power and other data to assist in monitoring system operation status and energy measurement.
Protective components: such as circuit breakers, surge protectors (SPDs), isolating switches, etc., providing multiple protections against overcurrent, overvoltage, lightning strikes, etc.
Application scenarios and advantages
The grid connected net cage is widely used in distributed photovoltaic systems (such as household roofs, industrial and commercial power stations), especially suitable for the grid connected mode of "self use, no surplus electricity connected to the grid". By precisely controlling the flow of electrical energy, it can not only improve energy utilization efficiency, but also avoid problems such as grid fluctuations and metering disputes caused by backflow, ensuring the stable operation of the power grid.
In practical applications, the parameters of the net cage (such as anti backflow setting) can be configured according to the requirements of the power grid and system scale. Some models support remote monitoring and communication functions, further improving management convenience.