AC Settings - Iron Edison

AC Settings - Iron Edison
AC Settings
AC Settings
The AC Settings menu configures the voltage and frequency limits for
AC port 1 (Grid) and AC port 2 (Gen). These are the limits at which the Xantrex
XW Series Inverter/Charger considers input voltage qualified—that is, suitable for
charging batteries or powering loads. If the input voltage is not qualified
according to these settings, the Xantrex XW Series Inverter/Charger transfers
from using AC input to inverting.
Important: The Xantrex XW Series Inverter/Charger is configured from the factory
as a split-phase inverter. In order to qualify the input, the AC input to the inverter
must be split phase: VLine1–Neutral + VLine2–Neutral = VLine1–Line2. The Xantrex XW
Series Inverter/Charger can be configured for single-phase operation (120 V only).
A split-phase Xantrex XW Series Inverter/Charger cannot accept input from a
three-phase source unless the inverter is converted to single-phase operation and
connected to a 120 V leg. See Appendix D, “Split-Phase to Single-Phase
Conversion Instructions” in the Xantrex XW Power System Installation Guide for
more information about three-phase operation.
Table 3-5 AC Settings Menu
Item
Description
AC Priority
Sets the priority for the AC source (AC1 or AC2) for qualification and transfer.
For example, if you set this to AC2, the Xantrex XW Series Inverter/Charger will use a
renewable energy source (such as an AC hydro generator) connected to AC2. It will use
utility power only when renewable energy is insufficient or unavailable to power loads.
In systems that use both utility grid (AC1) and generator (AC2) input, it is recommended that
you set AC Priority to AC1. Assuming the generator is intended for occasional use only,
the Xantrex XW Series Inverter/Charger will use utility power. It will use the generator only if
AC1 is unavailable, and if the generator is running.
AC1
Breaker
Sets the AC1 (Grid) breaker size, based on the size of the breaker installed on AC1.
The installed breaker size must not exceed the capacity of the upstream distribution
panel. The Xantrex XW Series Inverter/Charger limits the maximum input current to this
setting by derating its charging current to an equivalent of 80% of the AC breaker size. If
the connected loads exceed the AC1 breaker setting, the AC breaker trips. The breaker
may not trip if grid support is enabled and battery voltage is above the
Grid Supp Volts setting, or if peak load shave is enabled and the load shave time
window is active.
AC1 Lo Volt
Minimum acceptable input voltage level from the utility grid.
AC1 Hi Volt
Maximum acceptable input voltage level from the utility grid.
AC1 Lo Freq Minimum acceptable utility grid input frequency.
AC1 Hi Freq Maximum acceptable utility grid input frequency.
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Configuration
Table 3-5 AC Settings Menu
Item
Description
AC2
Breaker
Sets the AC2 (Gen) breaker size, based on the size of the installed AC breaker. The
breaker size must not exceed the capacity of the generator. The Xantrex XW Series
Inverter/Charger limits the maximum input current to this setting by derating its charging
current to an equivalent of 80% of the AC breaker size. If the connected loads exceed the
AC2 breaker setting, the AC breaker trips. The breaker may not trip if Gen Support is
enabled and Gen Amps is configured not to exceed the generator’s rated output current.
AC2 Lo Volt
Minimum acceptable input voltage level from the generator.
AC2 Hi Volt
Maximum acceptable input voltage level from the generator.
AC2 Lo Freq Minimum acceptable generator input frequency.
AC2 Hi Freq Maximum acceptable generator input frequency.
For default settings, see “AC Menu” on page B–4.
Grid Support Settings
The Grid Support Settings menu contains configuration options for
grid-tie operation. To enable all these settings, Grid Support must be
enabled in the Setup menu (see “Xantrex XW Series Inverter/Charger Setup
Menu” on page 3–2).
Important: Grid support and sell functions are modes of operation that are
subject to local and/or national grid interconnection requirements in most
jurisdictions. It is the responsibility of the installer and system operator to ensure
that all applicable procedures and technical requirements are complied with
before turning on either of these modes.
Note: Upon startup, the Xantrex XW Series Inverter/Charger does not enable
grid support functions for five minutes (300 seconds). During this period the
Xantrex XW Series Inverter/Charger connects to AC input and determines
whether the utility grid voltage and frequency are stable and within nominal
range. If Grid Support is enabled, the inverter information panel also
displays a 300-second countdown during this period. For more information,
see “Islanding Protection” on page 1–4.
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Grid Support Settings
Table 3-6 Grid Support Settings Menu
Item
Description
Grid Supp Volts
Sets the level to which the batteries will be discharged when the inverter is selling
power to the grid or supporting the power grid by providing additional power to the
loads. This setting is not adjusted for the battery temperature even if the temperature
sensor is installed.
Sell
Turns sell mode on and off. When Sell is set to enabled, the Xantrex XW Series
Inverter/Charger AC output is divided between powering loads and delivering power
to the utility grid. Sell mode requires the battery voltage to be above
Grid Supp Volts. All configurations must comply with local and national electrical
codes. The renewable energy from the battery is exported to the grid as long as the
battery voltage is greater than or equal to Grid Supp Volts. See Figure 3-8 on
page 3–25.
• Grid-tie entry condition: battery voltage is greater than Grid Supp Volts.
• Grid-tie exit condition: battery voltage is lower than Grid Supp Volts less 0.5 V.
There is a time delay associated with the entry and exit conditions. The default is
20 seconds. The delay can be extended to 40 seconds if the battery voltage is not
very stable (Figure 3-3, “Basic and Advanced Settings” on page 3–6 and Table 3-12,
“Advanced Features Menu” on page 3–38). This delay helps to avoid sell power
fluctuations when the battery voltage fluctuates.
There is an exception. The delay is zero when the battery voltage suddenly changes
to 2 V above Grid Supp Volts. For example, when a wind turbine or micro-hydro
is connected to a small battery bank which may create a sudden change on the
battery voltage. In this case the system will immediately respond by converting the
energy from the battery to grid.
Max Sell Amps
Sets the maximum AC amps allowed to be delivered to the utility grid from a solar
array and/or the batteries during grid-tie operation. This setting is only used if Sell
is set to enabled.
Max Sell Amps must be less than 80 per cent of the selected AC1 breaker setting.
If set higher, the breaker setting will override the Max Sell Amps setting to avoid
tripping the breaker.
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Configuration
Table 3-6 Grid Support Settings Menu
Item
Description
Load Shave
Enables or disables the load shave feature. Load shave allows the Xantrex XW
Series Inverter/Charger to support the grid in powering local loads during a defined
window of time (set using Load Shave Start and Load Shave Stop). If
Load Shave is set to enabled:
• If the battery voltage is above Grid Supp Volts, then the current taken from
the grid is reduced to zero (see Figure 3-7, “Peak Load Shaving Mode” on page
3–23). This maximizes the renewable energy for AC load usage.
• If battery voltage is below Low Batt Cut Out +2 V, then it will exit load shave
mode and enter AC pass through mode.
• If battery voltage is reduced further to below Low Batt Cut Out +1 V, then it
will exit AC pass through mode and enter charge mode to fully recharge the
battery. Note that the Xantrex XW Series Inverter/Charger will only enter charge
mode during the load shave period if the battery voltage drops to
Low Batt Cut Out +1 VDC.
Load Shave
Amps
Sets the maximum amount of current that can be drawn from the AC1 (grid) input by
the loads and battery charger combined. This setting determines the amperage
level at which the inverter starts drawing power from the batteries to add to the utility
power to meet the demand of the loads.
Typically, this value is set to the size of the AC circuit breakers feeding the inverter’s
AC input or the peak usage surcharge threshold imposed by the utility, if applicable.
Load Shave Start Sets the time of day that the load shave feature operates. This feature is suited for
regions where local utilities impose peak usage surcharges. The inverter provides
load shaving power as long as battery voltage is 2 V or more above
Low Batt Cut Out. See Figure 3-7, “Peak Load Shaving Mode” on page 3–23.
Load Shave Stop Sets the time of day that the load shave feature stops operating. If Load Shave is
set to enabled and Load Shave Start and Load Shave Stop are set to the
same time, the Xantrex XW Series Inverter/Charger load shaves continuously.
For default settings, see “Grid Support Menu” on page B–5.
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Grid Support Settings
Battery
Voltage
Peak Load Shaving Mode
Grid Support Mode
[Grid Support Volts ]
Peak Load Shaving Mode
[LBCO]+2V
AC PassThrough Mode
[LBCO]+1V
Charge Mode
Time
Figure 3-7 Peak Load Shaving Mode
Energy Management
The Xantrex XW Series Inverter/Charger can be programmed to control how and
when to use utility power. Advanced features allow management of peak loads
and time-of-use billing.
Charger Block
See “The Xantrex XW system will still allow manual equalize charging when the
boost absorption voltage is implemented.” on page 3–17.
Grid Support
Important: Grid support and sell functions are modes of operation that are
subject to local and/or national grid interconnection requirements in most
jurisdictions. It is the responsibility of the installer and system operator to ensure
that all applicable procedures and technical requirements are complied with
before turning on either of these modes. The interconnect codes and standards
with which the Xantrex XW Series Inverter/Charger complies are listed in the
Specifications section.
The grid support feature allows the Xantrex XW Series Inverter/Charger to
support local loads by converting excess capacity from external DC sources
connected to its battery bank. Examples of external DC sources are charge
controllers, micro-hydro, and wind turbines.
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Configuration
For grid support to function, Grid Support must be enabled on the Setup
menu and the battery voltage must be above the Grid Supp Volts setting.
There are two modes of operation within grid support.
Grid Support enabled, Sell disabled In this mode, available excess DC power
is converted and used to power local loads. No power is exported to the utility. If
the local load demand exceeds the available power from the external DC
sources, power is then drawn from the utility to support the load. However, if the
local load demand is less than the power available from external DC sources, the
net excess power from the external DC sources is not converted and hence
not used.
Grid Support enabled, Sell enabled In this mode, all available excess DC
power is first used to power local loads. Any remaining power is exported to the
utility grid.
Grid Support and Battery Charging
Charge Cycle
settings
With the charger enabled, the Xantrex XW Series Inverter/Charger enters grid
support mode only after completing a charge cycle when it is first powered up or
reconnected to the grid. Set Charge Cycle to 2-stage (default) to allow grid
support to function immediately after the absorption charge stage. See “Charger
Settings Menu” on page 3–10.
Grid Support
modes
Grid support can be configured to operate in one of two modes.
Fixed battery voltage This mode is suitable for systems with DC sources
(such as wind turbines, DC generator sets, fuel cells, and so on) that are not
connected to the Xantrex XW Series Inverter/Charger through Xanbus or for
mixed systems which have both Xanbus-connected Xantrex XW Solar Charge
Controllers and other DC sources (such as those listed above). In this mode,
Grid Supp Volts is set about 0.5 volts below the voltage provided by the DC
source (typically the float voltage setting of the DC source or charge controller).
See Figure 3-8, “Grid-tie Sell Mode” on page 3–25.
In fixed battery voltage mode the Xantrex XW Series Inverter/Charger tries to
regulate the battery voltage to the Grid Supp Volts setting by converting the
available DC power to AC power to support the loads or export to the utility grid.
Because the battery bank voltage may not reach bulk/absorption voltages in this
mode, it is recommended to occasionally force a full charge cycle by either
temporarily disabling grid support or forcing a bulk charge cycle from the grid
(see “Force Chg” on the “Xantrex XW Series Inverter/Charger Setup Menu” on
page 3–2).
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Grid Support Settings
Enhanced interactive mode This mode is suitable for Xantrex XW Systems with
only Xantrex XW Solar Charge Controller(s) networked to Xantrex XW Series
Inverter/Charger(s) through Xanbus. In this mode, Grid Supp Volts is set as
the charge controller’s Bulk and Absorb voltages (for example, 32 volts on a
24 volt system and 64 volts on a 48 volt system).
In enhanced interactive mode the Xantrex XW Series Inverter/Charger
automatically tracks the Xantrex XW Solar Charge Controller voltage as it
transitions through all charge states (from bulk to absorption to float). This allows
the Xantrex XW System to execute a full battery charge cycle while still
converting excess DC power to AC power to support the loads or export to the
utility grid. In doing so, the Xantrex XW Series Inverter/Charger only uses what is
not accepted by the battery to support local loads and sell to the grid, thereby
maximizing the use of the array. Since this mode allows the battery bank voltage
to reach absorption levels (when PV harvest is adequate), the state of health of
the battery is improved. The sell entry and regulation voltage level is 1 V below
absorption and float of Xantrex XW Solar Charge Controller set points. The sell
exit from sell is 1.5 V below absorption and float of Xantrex XW Solar Charge
Controller set points.
Fixed Battery Voltage
Battery
Voltage
Sell Mode
Enhanced Interactive Mode
Grid-tie Sell Mode
Fast Re-Entry Sell Mode: no [Tdelay]
Battery
Voltage
[Grid Supp Volts ]+2V
Enhanced Interactive Mode
Vabsorption
Vfloat
Battery Voltage Regulation
Re-Entry Sell Mode +[Tdelay]
Vabsorption -1V
[Grid Supp Volts ]
Vfloat-1V
Exit Sell Mode +[Tdelay]
[Grid Supp Volts ]-0.5V
Time
Actual charge Voltage level
Note: [Tdelay]= 20 sec default
[ Tdelay]=adjustable: Advanced/Adv Features selectable to 40sec.
MPPT setting charge Voltage level
Time
Figure 3-8 Grid-tie Sell Mode
Note:
[Tdelay] is an entry/exit transition time delay to/from grid support and sell mode.
If the battery voltage has higher fluctuations due to DC renewable sources
(e.g. charge controllers, wind turbines, and so on), then the time delay can be
increased by setting Sell Dly 40s to enabled (Table 3-12, “Advanced
Features Menu” on page 3–38).
If the battery voltage has a sudden increase change greater than
Grid Support Volts + 2 V, then the Xantrex XW Series Inverter/Charger will
override the delay and enter grid support or sell mode immediately.
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Configuration
Peak Load Shaving
Many utilities impose a surcharge on their customers based on the peak load
used by a facility. To reduce utility peak demand charges, the inverter can be
configured (using the Load Shave Amps setting) to limit the maximum draw the
AC loads place on the utility. The inverter can be programmed to provide power
above a specified level, eliminating the surcharge. When the utility current draw
reaches the maximum level, the inverter assists by providing power from the
batteries to the loads.
For peak load shaving to be effective, all loads must be connected to the inverter.
For large loads, multiple (or stacked) inverters may be required.
To further make sure the batteries are able to supplement the power
requirements of the connected load, an additional source of power (solar, wind,
or hydroelectric) is recommended.
Peak load shaving can also be used in addition to the time-of-use metering.
Time-of-Use Metering
Utilities use time-of-use metering to determine utility charges during peak usage
hours and to impose a surcharge. The Xantrex XW Series Inverter/Charger can
be configured (using the Load Shave Start, Load Shave Stop and
Charger Block settings) to overcome these peak charges by using utility
power to charge the battery bank during the inexpensive energy hours and
consuming the battery energy during expensive energy hours.
For example, if Charger Block is set between 9:00 AM and 10:00 PM and
Load Shave is set between 6:00 PM and 9:00 PM, charging on AC1 stops at
9:00 AM and continues to pass utility AC through to the loads. If charging is
required during the charger block period, and AC Priority is set to AC2, the
Xantrex XW Series Inverter/Charger can use any AC source connected to AC2.
Loads will transfer to the AC source on AC2 as well. The inverter connects to the
utility grid at 6:00 PM and supports loads using the batteries. The inverter
continues to run until 9:00 PM. The Xantrex XW Series Inverter/Charger then
stops supporting the utility grid and passes utility AC through to the loads. At
10:00 PM utility AC begins maintaining the batteries based on the battery
charger settings.
The above example allows an external renewable energy source to be utilized as
a primary charging source during a desired time window. The charger
(using utility AC connected to AC1) can then be used to supplement the battery
charging when the utility rates are low.
When using the system for time-of-use metering, the system should be designed
with a battery capacity large enough to support loads during the entire peak rate
period without reaching the Low Batt Cut Out setting.
To further make sure the batteries are able to support the loads, an additional
source of power (solar, wind, or hydroelectric) is recommended. Depending
upon the capacity of the system, certain heavy loads should only be run during
non-peak periods.
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