Understanding the DC string parameters on multi-string inverter
DC String: DC control mode
Address
53650
Description
There are two different modes:
constant current mode
set these registers to 0, the register DC String: DC current setpoint will take effect, DC String: DC power setpoint will be ignored. The inverter will dis-/charge consisting with DC String: DC current setpoint, no matter what's the battery voltage.
constant power mode
set these registers to 1, the register DC String: DC power setpoint will take effect, DC String: DC current setpoint will be ignored. The inverter will charge or discharge consisting with DC String: DC power setpoint, the dis-/charging current will be depending on the quotient of power setpoint divided by battery voltage.
DC String: DC current setpoint
Address
53651
Description
Available only when both conditions are achieved:
- Dispatching mode(53601) is set to 1, DC dispatching mode
- DC String: DC control mode is set to 0
- The battery is not in topping charge procedure
DC String: DC power setpoint
Address
53652
Description
Available only when both conditions are achieved:
- Dispatching mode(53601) is set to 1, DC dispatching mode
- DC String: DC control mode is set to 1
- the battery is not in topping charge procedure
DC String: DC lower voltage threshold
Address
53653
Description
this threshold should always be lower than DC String: end-of-discharge voltage
DC String: end-of-discharge voltage
Address
53655
Description
Available only when the following condition(s) is(are) achieved:
- Dispatching mode(53601) is set to 1, DC dispatching mode
This is the first-level undervoltage protection threshold. When the battery voltage reaches this threshold, the inverter will refuse to discharge, but will not trip.
This threshold should be set higher than DC String: DC lower voltage threshold
DC String: precharge voltage
Address
53656
Description
Available only when the following condition(s) is(are) achieved:
- Dispatching mode(53601) is set to 1, DC dispatching mode
This register is rarely used
DC String: precharge to fast charge transition voltage
Address
53657
Description
Available only when the following condition(s) is(are) achieved:
- Dispatching mode(53601) is set to 1, DC dispatching mode
This register is rarely used
DC String: precharge time
Address
53658
Description
Available only when the following condition(s) is(are) achieved:
- Dispatching mode(53601) is set to 1, DC dispatching mode
- The battery is in very low SOC condition
This PRECHARGE is not the resistor PRECHARGE for preventing in-rush current to DC link capacitor
DC String: float charge voltage
Address
53659
Description
Available only when the following condition(s) is(are) achieved:
- Dispatching mode(53601) is set to 1, DC dispatching mode
- lead acid battery
In case of lithium-ion batteries, this register MUST be set as same as DC String: topping charge voltage
DC String: topping charge voltage
Address
53660
Description
When the battery voltage reaches this setpoint, the inverter will switch to constant voltage output, and will reduce the current to maintain the topping charge voltage.
DC String: topping charge to float charge transition current
Address
53661
Description
This register is for lead-acid battery ONLY, in case of lithium-ion battery, this register MUST be set to 0
when the charging current in topping charge procedure reaches this threshold, the inverter will change to float charge
DC String: end-of-charge current
Address
53662
Description
In topping charge procedure, when the charging current reaches this threshold, the inverter will stop charging, the IGBT will stop switching, but the relays are still closed.
DC String: maximum charge current
Address
53663
Description
At any time,
- The DC charging current will NOT exceed this register,
- The DC charging power will NOT exceed the product of battery voltage times this register
DC String: maximum discharge current
Address
53664
Description
At any time,
- The DC discharging current will NOT exceed this register,
- The DC discharging power will NOT exceed the product of battery voltage times this register
DC String: maximum precharge current
Address
53665
Description
This register is rarely used