Setting Time-Dependent Two-Level Load Shedding
The basic procedure for changing operating parameters is explained in another section ( > Changing Operating Parameters).
The time-dependent load shedding divides the day into two intervals ( > Setting Time-Dependent Functions). You set the SOC thresholds that apply for each interval for two-level load shedding. For example, you can set that as far as possible no loads are to be disconnected from the utility grid during the day.
Significance of the SOC thresholds:
Two lower and two upper SOC thresholds are available for each interval for controlling the load-shedding contactors. The load-shedding contactors disconnect the loads from the utility grid if the states of charge are as follows:
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When the state of charge of the battery reaches the first lower SOC threshold, the multifunction relay opens the connected load-shedding contactor for the first level of load shedding. The load-shedding contactor disconnects those loads from the utility grid that are to be disconnected for the first level.
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When the state of charge of the battery reaches the second lower SOC threshold, the multifunction relay opens the connected load-shedding contactor for the second level of load shedding. The load-shedding contactor disconnects the remaining loads from the utility grid.
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When the state of charge of the battery reaches the second upper SOC threshold during recharging, the multifunction relay closes the connected load-shedding contactor for the second level of load shedding. The load-shedding contactor connects those loads to the utility grid that were disconnected for the second level.
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When the state of charge of the battery reaches the first upper SOC threshold during recharging, the multifunction relay closes the connected load-shedding contactor for the first level of load shedding. The load-shedding contactor connects those loads, which were disconnected for the first level, to the utility grid. All loads are connected to the utility grid.
Procedure:
- Select Device > Load shedding 1 > Additional time range.
- Set the parameter Time load shedding 1 to the start time for the first interval.
- Set the parameter Start time additional time range load shedding 1 to the start time for the second interval.
- Set the SOC threshold for the standard time period:
Select Device > Load shedding 1.
Set the parameter Lmt value battery state of charge for start load shedding 1 to the lower SOC threshold for the first level of load shedding.
Set the parameter Lmt value battery state of charge for stop load shedding 1 to the upper SOC threshold for the first level of load shedding.
Select Device > Load shedding 2.
Set the parameter Lmt value battery state of charge for start load shedding 2 to the lower SOC threshold for the second level of load shedding.
Set the parameter Limit battery state of charge for stop load shedding 2 in add time range to the upper SOC threshold for the second level of load shedding.
- Set the SOC threshold for the additional time period:
Select Device > Load shedding 1.
Set the parameter Limit battery state of charge for start load shedding 1 in add time range to the lower SOC threshold for the first level of load shedding.
Set the parameter Limit battery state of charge for stop load shedding 1 in add time range to the upper SOC threshold for the first level of load shedding.
Select Device > Load shedding 2.
Set the parameter Limit battery state of charge for start load shedding 2 in add time range to the lower SOC threshold for the second level of load shedding.
Set the parameter Limit battery state of charge for stop load shedding 2 in add time range to the upper SOC threshold for the second level of load shedding.
- Ensure that the multifunction relay used for controlling the first level of load shedding is set to 1-stage load shedding or 1st stage with 2-stage load shedding ( > Setting the Functions of the Multifunction Relays).
- Ensure that the multifunction relay used for controlling the second level of load shedding is set to 1st stage with 2-stage load shedding.