Battery protection settings field definitions

Description

Battery protection settings are storage point settings that limit what the Target Power rules of the point can do. For the rules, see Build a rule list.

• Settings: the Protection and Emg. Charge tabs of the storage point.
• Open the settings: set Edit to on, then double-click the point.
• Data: click the point with Edit off.
• Save: saves all tabs at the same time.
• Changes: Editor, Installer or Full control.
• Out of range: the logger refuses the value.

BMS Limits

Plant control keeps charge and discharge in the current limits that the BMS reports.

• Charge limit: the BMS charge current limit, less Charge Control Offset, times the battery voltage.
• Discharge limit: the BMS discharge current limit, times the battery voltage.

Protection Tab

• Load Reserve: %, default 25, range 0 to 100. Off-grid supply held back from controllable loads, as a percentage of the forming converter rated power. Used off grid only.
• Charge Control Offset: %A, default 10, range 0 to 100. A margin below the BMS charge current limit, as a percentage of the rated charge current. A larger value gives a lower charge limit.
• Freq Top Offset: Hz, default 2. The largest frequency offset that plant control requests while the BMS charge current limit is below 50 %.
• Freq Bottom Offset: Hz, default 2. The logger does not use it.
• Freq Step: Hz, default 0.01. The change of the frequency offset in each control cycle.

Only the Sungrow SC HV Series converter acts on the frequency offset.

Emg. Charge Tab

Over-discharge protection force-charges a battery when the BMS discharge current limit stays low. During the force charge, the battery does not follow the Target Power rules.

• Over-discharge protection: default Enabled. Disabled stops the protection and ends an active force charge.
• Reset Emg. Charge: the Reset item in its menu clears the force charge. If the discharge current limit stays low, the delay starts again.
• Disch. Ctrl Level: %, default 80, range 0 to 99. The BMS discharge current limit, in percent, below which the delay starts.
• Emg. Charge Delay: s, default 30, range 0 to 60. The time below Disch. Ctrl Level before the force charge starts. The delay resets if the limit recovers first.
• Recover Delta SOC: %, default 5, range 0 to 100. The rise in state of charge, from the start of the force charge, before plant control permits discharge again.
• Emg. Charge Power: %, default 5. The force charge power, as a percentage of the smaller value: the charge limit or Allowed Charge Increase.
• Release: the state of charge has risen by Recover Delta SOC, and the BMS discharge current limit is back at 100 %.

Storage Point Data

• Discharge, Current %: the BMS discharge current limit that Disch. Ctrl Level compares.
• Allowed Charge Increase: W. The charge limit less the battery power at this time.
• Allowed Disch Increase: W. The discharge limit plus the battery power at this time.
• Remaining Activation Delay: s. The time left of Emg. Charge Delay, or -- when no delay runs.
• Remaining SOC Recovery: %. The state of charge rise that is necessary for release, or -- when not in force charge.
• Force Charge (over-discharge): on a storage group point. Inactive, or ACTIVE: followed by the storage IDs in force charge.

Tips

• If the battery does not follow a discharge rule near empty, examine Remaining SOC Recovery. A value means that a force charge is active.
• Keep a discharge floor above the state of charge at which the BMS discharge current limit falls below Disch. Ctrl Level. Below it, the force charge and the discharge rule work against each other.