Anti-reverse device Dual control protection + adjustment

Review: Suitable for 1-n inverters (number of inverters, order instructions) power generation occasions, such as villas, home photovoltaic, small factories and other small-capacity photovoltaic power generation systems. 

For the photovoltaic grid-connected power generation system on the low-voltage distribution network side, it is generally believed that the photovoltaic power generation power should not be more than 20% of the capacity of the upper distribution transformer on the grid-connected side (according to the local power grid requirements). At present, the power grid companies usually require the photovoltaic grid-connected system to be an irreversible current generation system, that is, the power generated by the photovoltaic grid-connected system is consumed by the local load, and the excess power is not allowed to be transmitted to the upper power grid by the low-voltage distribution transformer. In the grid-connected power generation system, because the external environment is constantly changing, and the system needs to be equipped with a set of anti-reverse device. In order to prevent the reverse generation of the photovoltaic grid-connected system

Takingthe ZNDQ-9580 regulating inverter communication module photovoltaic anti-reverse protection device as an example, the main core principle of this period is to judge the current direction as the standard. As shown in the figure: A is the grid side, the reverse power current acquisition and detection tap point, C is the photovoltaic side, B is the user's electricity load side; 

1.If the power of photovoltaic power generation at C is the power of the load, there is no need to prevent reverse;

2.If the power of photovoltaic power generation at C is > the power of the load at B, an anti-reverse device is needed at this time. At this time, the current on the photovoltaic side goes 

3.When crossing the tap point A on the grid side, the power acquisition will become negative; 

a) In the case of multiple photovoltaic power sources, you can choose to cut off one or several until the power of photovoltaic power generation at C is ≤ the power of the load at B. 

b) When there is only one photovoltaic power source, you can choose to limit the power of photovoltaic power generation or increase the load until the power of photovoltaic power generation at C ≤ the power of the load at B. At this time, the ZNDQ-9580 regulates the inverter communication device It will issue a trip command to the photovoltaic side gateway or inverter (prioritize adjusting the power output of the inverter), cut off a certain grid-connected switch or control the inverter (prioritize adjusting the inverter output), and then judge whether there is any inverse power situation. If so, continue to cut off other grid-connected switches or inverters (adjust the power output of the inverter first) until there is no inverse power situation. When the electricity load increases again, at this time, because part of the power of photovoltaic power generation is disconnected, and the device detects the direction of the current on the grid side to the load end, it is judged that the electricity generated by the photovoltaic side is not enough for the load. At this time, the device will automatically issue a closing command or increase the inverter (adjust the power output of the inverter).

Detailed description of anti-reverse control process: 

1. Give priority to the use of communication regulation inverter power devices 

2.When the communication regulating inverter power device ZNDQ-9580 reads that the power load of the incoming line of the host of the anti-reverse device is very small or there is reverse (photovoltaic power generation load C > power load B), the regulating inverter power device can quickly calculate and process real-time control.

3.The power of all inverters below the system drops, so that the power consumption of the system is always at the forward power (power load B-photovoltaic power generation load C > 0); When the electrical load rises to a certain extent (the power parameters can be adjusted), the power adjustment device of the inverter can quickly measure.

4.The calculation process controls the power of all inverters below to rise slowly in real time, and can keep the system power load in the forward power of the incoming line side A (power load B-photovoltaic power generation load C > 0).

5.The host of the anti-reverse device starts the second reverse power protection jump function (for details, please refer to the function introduction of the device manual) 

6.The host of the low-voltage anti-reverse device controls the main circuit breaker of the photovoltaic grid-connected grid-connected cabinet through the trip-closing outlet as a backup protection function to avoid data transmission problems caused by on-site communication lines, communication equipment failures and signal interference; At this time, the host reverse power protection function or low positive power protection of the low-voltage anti-reverse device can be used to quickly trip the grid-connected circuit breaker. The load power consumption can also be greater than photovoltaic power generation, and the power recovery protection outlet can control the grid-connected circuit breaker to automatically close.