Setting Export Limitation Parameters

Network Application

When the PV plant itself generates power for private use only, the loads cannot consume all the power and countercurrent may feed into the power grid. Therefore, users need to set the export limitation parameters over the WebUI to prevent countercurrent.

• Scenario without a circuit breaker: The countercurrent feeding into the power grid can be eliminated by sending a command from the SmartLogger to lower the inverter output power.
• Scenario with a circuit breaker: When the countercurrent feeding into the power grid cannot be eliminated by sending a command from the SmartLogger to lower the inverter output power, and the Maximum protection time is exceeded, the SmartLogger drives the relay to switch off the circuit breaker by controlling the DO port. When the DI port detects that the circuit breaker is open, the DO port and relay on the SmartLogger will be switched off, and the SmartLogger will restore to the initial state.

Figure 7-61 Network diagram (without a circuit breaker)

Figure 7-62 Network diagram (with a circuit breaker)

In the scenario with circuit breaker, put the power supply position of the SmartLogger before the circuit breaker to avoid the SmartLogger power-off after the DO control circuit breaker is switched off.

Setting Parameters

Before setting the parameters, ensure that the Modbus power meter and inverter are connected to the WebUI. Then take the following steps to complete the settings.

1. Log in as Advance User, choose Monitoring > SUN2000 > Running Param. > Feature Parameters, and set the following parameters.

   Parameter	Description	Recommended Value
   Communication interrupt shutdown	The standards of certain countries and regions require that the inverter must shut down after the communication is interrupted for a certain time.	Enable
   Communication resumed startup	If this parameter is enabled, the inverter automatically starts after communication recovers. If this parameter is disabled, the inverter needs to be started manually after communication recovers.	Enable
   Communication interruption duration	Specifies the duration for determining communication interruption, and is used for automatic shutdown for protection in case of communication interruption.	1
   Soft start time	Specifies the duration for the power to gradually increase when the inverter starts.	20
   Soft start time after grid failure	Specifies the time for the power to gradually increase when the inverter restarts after the power grid recovers.	20

2. Log in as Special User, choose Monitoring > SUN2000 > Running Param. > Adjustment, and set the following parameters.

   Parameter	Description	Recommended Value
   Plant active power gradient	Adjusts the rate of active power rise due to light changes.	0
   Active power change gradient	Adjusts the change speed of the inverter active power.	125%/s If the maximum value is 50%/s, set this parameter to 50%/s.

3. Log in as Special User and choose Settings > Active power control. Ensure that Active power control is set to Disable.

4. Log in as Special User and choose Settings > Export Limitation.

   Figure 7-63 Setting Export Limitation Parameters
   

   Parameter	Description
   Power Meter	If Export Limitation is set to Enable, set Power Meter to Smart meter. Otherwise the function would not take effect.
   Electric meter power direction	When the inverter has no output power, set this parameter to positive if the active power reading of the power meter is positive. Otherwise, set this parameter to reverse.
   Load	Load Balance: backflow prevention for the total power of the grid-tied point Load Imbalance: backflow prevention for each phase of the grid-tied point
   Maximum grid feed-in power	Setting the maximum power that the inverter can feed into the power grid. Suggestion: Set this parameter based on the countercurrent threshold allowed by the power grid company.
   Power lowering adjustment period	Setting the inverter output power lowering period.
   Maximum protection time	Setting the maximum duration from the time the SmartLogger detects countercurrent to the time it controls the inverter output power to reach 0. Suggestion: Set this parameter based on the maximum countercurrent duration allowed by the power grid company.
   Power raising threshold	Setting the inverter output power raising threshold.
   Power limit for abnormal electric meter	Setting the inverter output power percentage controlled by the SmartLogger when communication between the SmartLogger and the power meter is abnormal.
   Switch-off with 0% power limit	Setting whether to switch off the DO port. When this parameter is set to Enable, the settings of the Switch-off control port, Switch-on control port, Switch-off state feedback port, and Switch-on state feedback port are also enabled.