8 Reference
8.1 Power source prioritizing
eSite x10 uses the following power source priority order:
Solar power
Grid power
Genset power
If solar or grid is not available, the genset automatically starts when the batteries must be charged. If grid becomes available during a genset charge, the genset is stopped. Only one AC source can be active at the time. If solar power becomes sufficient, this can also stop the genset, utilizing the Green Power Influx feature. If solar power is available at the same time as grid or genset power is available, solar power is always prioritized and maximized.
8.2 Silicon Controlled Rectifier (SCR) with ATS functionality
The Main Compartment converts the AC supply via three rectifiers into -48 V DC. The rectifiers provide 3.5 kW per unit, for a total of 10.5 kW. The inputs from the AC sources are continuously measured to ensure that the most efficient AC source is used. The switching between the connected AC sources (gensets/grid) is automatic.
The eSite x10 patented Silicon Controlled Rectifier (SCR) is designed to improve the performance of the system compared to a traditional Automatic Transfer Switch (ATS). Both an ATS and SCR allows for switching between two AC sources, but while the ATS is based on mechanical switching, the SCR uses power semiconductors.
One or two (optional) AC sources can be configured in the eSite Web interface. The options are No Source, AC Genset 1 and 2 and Grid.
8.3 System mode
The eSite x10 can be in 4 different system modes: 'Auto', 'Auto Full Charge', 'Manual' and 'Safe Mode'.
8.3.1 Auto
Auto mode is the normal mode the system operates in. The eSite x10 is working automatically with no user interference and controls all features and external command signals.
8.3.2 Auto Full Charge
Auto full charge mode is activated when the batteries need to do a Full Charge cycle.
The following conditions activate a full charge:
One of the Load Voltage Disconnect (LVD) breakers has tripped.
The time interval between two Full Charge cycles has elapsed. This parameter can be changed in local web configuration.
The battery Energy throughput has reached its limit value. This parameter can be changed in local web configuration.
See section Full charge cycles
8.3.3 Manual
Manual mode is activated when a controlled AC source, typically a genset, is manually forced on or off. This can be done from the local web pages or remotely via eSite Tools.
In Manual mode normal functionalities, including power prioritizing and automatic external commands, are overridden. Manual mode is exited when all AC source controls are set to Auto.
8.3.4 Safe Mode
Safe mode is activated when the battery MCB is tripped or if eSite x10 cannot determine the correct state of the battery bank. For example: If one or both of the battery voltage or current sensors have failed, the eSite x10 will enter Safe mode.
For the case when no battery MCBs are present and configured as “No Input”, Safe Mode is activated by the following conditions:
Voltage sensor mismatch alarm is active (system and battery voltage sensors differ by > 1V)
System and battery voltage sensors are valid
Genset is running and gives feedback
No battery charge current detected (measured value less than configurable threshold, default 2 A)
These conditions combined indicate that no battery bank is present and eSite x10 will enter Safe Mode. This applies for lead-acid batteries only.
When Safe mode is active, the voltage levels and the maximum battery charge current are reduced and the genset is commanded to continue running.
8.4 Batteries
eSite x10 supports usage of two different types of battery chemistry : lead-acid batteries and lithium-ion (Li-ion) batteries. Several different brands, models and sizes of batteries have premade configurations that simplifies site commissioning and operation. New premade configurations can be created upon request. The battery parameters are also possible to set individually through several interfaces (e.g. eSite Web, eSite Tools, SNMP) in order to support new battery types and to improve performance.
8.4.1 Lead-acid batteries
Traditionally, conventional lead-acid batteries has been the main choice for hybrid operation on remote sites. They are attractive for a wide variety of usage due to being of relatively low cost, having a long life-time and high reliability, but they also come with drawbacks including the need for temperature compensation and bulky storage, especially for high-capacity banks.
Use of up to two (2) battery banks is supported, each with a separate charge current measurement sensor. This option is called Dual battery bank.
8.4.1.1 Voltage levels
Two different set voltage levels are used when charging lead-acid batteries: Boost voltage and Float voltage.
Boost voltage is higher than float voltage and is used to improve the charge performance. However, batteries kept at boost voltage for longer periods of time eventually take damage. Float voltage is lower and is used for long periods of continuous available AC power, for example when Grid is present for a long time.
8.4.1.2 Battery states
The following battery states are defined for lead-acid batteries. The states indicate at what stage in the charge cycle the battery bank is. The battery state information is available on eSite Web. If Dual battery banks are installed, the battery state is considered to be the same for both battery banks.
Discharge: The discharge state is entered when current is drawn from the batteries and the voltage is decreasing.
Charge: Charging occurs when either eSite x10 rectifiers or solar converters are delivering constant charging current to the batteries.
Absorb: Absorb is a charging state where the charging voltage is limited by the rectifiers or solar converters. The charging voltage has an optional temperature compensation feature. When in the Absorb state the battery bank is charged at constant voltage.
Equalized: Equalized is an extended constant voltage charging mode to help eliminate soft sulfation in lead-acid batteries. The voltage level is adjustable.
Fully Charged: In the Fully Charged state, the batteries are considered to be fully charged. The battery bank will remain in this state until SOC has dropped 5 % since the fully charged state was entered.
8.4.1.3 Battery charge strategies
eSite x10 offers four battery charge strategies to optimize the use of the lead-acid battery bank used on site. Battery charge parameters can be viewed on eSite Web under the Battery menu.
Voltage control
The battery bank starts to charge at specified voltage levels. The charging stops when a specified voltage level is reached and the charge current falls below a specified value. The method does not take into account the state of charge.
Used with a basic battery bank. The use of batteries is not optimized. The life-time of the battery bank is relatively short.
Static state of charge (SSOC)
The batteries start and stop charging at predefined levels of the state of charge. The SOC values for starting and stopping charge cycles is dependent on battery configuration and can be changed in the local web pages.
Used with battery bank delivered with proper data. SSOC gives a good estimation of the battery life-time. This method is convenient for a very remote site were it takes a great effort to switch battery bank.
Partial state of charge (PSOC)
The batteries are charged up until the charging performance decreases, based on the charge acceptance of the battery. When the charge current has decreased below a specified threshold the normal charge cycle is finished. The SOC level when this occurs minus a SOC window, default 30 %, decides when the next charge cycle starts. SOC level when the normal charge cycle is finished depends on several factors.
Used with battery bank delivered with proper data. Partial state of charge saves fuel costs and is the most cost saving strategy. The life-time of the battery bank may be shorter than if the SSOC strategy is used. The batteries are charged with low current as it is fuel inefficient when the batteries have a poor charge acceptance. As the genset runs more efficiently at higher output power compared to when it is running at idle or has low output power, the frequency of genset maintenance is also lowered. Thus, PSOC is a fuel efficient option.
UPS AC mode
This is a special mode where the batteries are not cycled and AC power is not turned off when the batteries are fully charged. The AC power can be either Grid or genset.
8.4.1.4 Full charge cycles
A Full Charge cycle is a longer charge cycle that charges the batteries to the maximum available capacity. Periodic use of the Full Charge cycle is needed to maintain the health of the battery bank, balance battery banks/strings and to “recalibrate” the state of charge. A Full Charge cycle charges the batteries at boost voltage until the battery is in the Fully Charged state. A Full Charge cycle can be triggered manually, for example during site commissioning, or by one of these three threshold values:
Time interval
Energy throughput
Low voltage, used on Static SOC and Partial SOC charge strategies
An Extended Full Charge cycle is triggered when the battery voltage has fallen so low that both HP and LP LVD are activated. An extended full charge cycle prolongs the Full Charge cycle with an extra timer, default set to 18 hours. This is an effort to recover the battery bank from any damages caused by the low voltage. An Extended Full Charge cycle can also be triggered manually.
8.4.1.5 Charge Mode
The battery charge mode indicate what type of battery management that is currently active. The charge mode is independent of the selected charge strategy and gives information about whether the battery bank is subjected to normal charge cycling or if a scenario that overrides these settings is active, such as when a Full Charge cycle is triggered.
The active charge mode is presented under the Battery tab on eSite Web and in eSite Tools.
For handling of lead-acid batteries, one of the following charge modes is used.
Normal Charge: Standard hybrid operation is active. The battery bank is charged/discharged according to the selected charge strategy and its associated control parameters.
Full Charge: A Full Charge cycle has been triggered and is active.
Extended Full Charge: An Extended Full Charge cycle has been triggered and is active.
Safe Mode: eSite x10 is currently in Safe Mode and cannot determine the correct state of the battery bank. Maximum allowed charge current and set voltages are lowered to protect the system.
8.4.1.6 Temperature compensation
The temperature is of great importance regarding the health of lead-acid batteries. The temperature information is used to adjust the voltage level when the batteries are charged. At high temperatures, the batteries are charged at a lower voltage level and at low temperatures batteries are charged at a higher voltage level. This temperature compensation can be configured.
The battery temperature sensor is placed in the centre of the battery bank (see figure 8.1) and connected to the eSite x10.
8.4.1.7 Current limit
eSite x10 continuously ensures that the battery max charge current is not exceeded. This threshold value for current limitation is configurable. The battery charge current is measured in the Main Compartment. A positive current indicates that the batteries are being charged. A negative current indicates that the batteries are being discharged.
8.4.2 Lithium-ion batteries
An increasingly popular alternative to lead-acid batteries for powering remote sites together with the eSite x10 is Li-ion batteries.
Due to their superior power density and sophisticated module designs, including the possibility of external communication, Li-ion batteries make for effective storage solutions of high capacity, combined with intelligent monitoring and managing, albeit at a slightly higher cost and a higher sensitivity to overcharging/overdischarging.
All commercial Li-ion battery modules relevant for this application are equipped with internal electronic protection, cell balancing circuits and supervision/alarm circuits.
eSite x10 is capable of managing a Li-ion battery bank of up to 16 installed BMUs connected in parallel. If a communication cable is mounted between the battery bank and the eSite x10, all alarms and important data (e.g. Voltage, SOC, Current) from the modules are logged, presented on the local web site and sent to eSite Tools. For operation without communication, or when communication is lost, this data is either measured or calculated by dedicated estimation algorithms based upon the available information about the battery type and the size of the battery bank.
eSite x10 ensures that charging voltage levels and maximum current stays within the limits according to the battery specifications. Maximum charge current is automatically adjusted depending on how many modules are connected or if any battery fuses are tripped.
Li-ion batteries from the following manufacturers are currently integrated with eSite x10. Contact eSite Power Systems for information regarding models and version.
LG Chem
Sacred Sun
SAFT
Shoto
Vision
Polarium (previously Incell)
See the Appendix, section Installation and configuration of lithium-ion battery for more information.
8.4.2.1 Voltage levels
When charging Li-ion batteries, a configurable set voltage level is used. For long periods of operation with available AC power, the set voltage is ramped down to a lower level to preserve the health of the battery bank.
These voltage levels are individual for each power source and may be preconfigured upon delivery. Normally, they are provided by the battery manufacturer.
8.4.2.2 Battery states
The following battery states are defined for Li-ion batteries. The battery state information is presented on eSite Web and in eSite Tools. For Li-ion configurations, all BMUs connected in parallel will be considered as one battery bank.
Precharge: Precharge is the initial state of the battery state algorithm. In Precharge, the system takes necessary precautions to stop inrush currents from going into the battery bank by slowly ramping up the system voltage from a low starting point until the battery voltage is matched. When current is detected going in or out of the battery bank, the Precharge state is exited.
Discharge: The discharge state is entered when current is drawn from the batteries and the voltage is decreasing.
Charge: The Charge state indicates that either the eSite x10 rectifiers or solar converters deliver enough current to charge the batteries.
Fully Charged: In the Fully Charged state, the batteries have met the manufacturer specifications for being considered fully charged and will not accept further charging. This state is exited when the SOC has decreased by 1 % since the Fully Charged state was entered.
Equilibrium State During equilibrium, no current flows in or out of the battery. This state is exited as soon as current going in or out of the battery bank is detected.
8.4.2.3 Li-ion battery charge strategies
eSite x10 currently offers two charge strategies to optimize the use of a lithium-ion battery bank on site: Voltage Control (VC) and Static SOC (SSOC). Battery charge parameters can be viewed on eSite Web under the Battery menu
The VC strategy works very similarly to the corresponding lead-acid strategy, see section Lead-acid batteries. Operation will be based on the overall measured battery voltage. This strategy is well suited for site setups with no battery communication or when SOC shall not be considered.
The static SOC strategy starts and stops charging based on configured Start SOC and Stop SOC levels. This is arguably the best adapted strategy for Li-ion battery banks with active communication to the eSite x10. The strategy offers several options to control the cycling based on the reported BMU data that are configurable via the Static SOC Control Options parameter. The options are
Average SOC - A charge cycle will start and stop when the average calculated SOC of the battery bank reaches the start/stop thresholds.
Protective SSOC - Start/stop on Min/Max BMU SOC value. A charge cycle will start when the minimum reported BMU SOC value reaches the Start SOC threshold and stop when the maximum reported BMU SOC value reaches the Stop SOC threshold. This behaviour will prevent overcharging and overdischarging of any single BMU in the bank.
Balancing SSOC - Start/stop on Min/Min SOC value. A charge cycle will start when the minimum reported BMU SOC value reaches the Start SOC threshold and stop when the minimum reported BMU SOC value reaches the Stop SOC threshold. This behaviour will ensure that all BMUs are charged up to the desired SOC .
Options 2 and 3 require active communication with the battery bank. In setups with no communication or if communication is lost, the SSOC strategy will be based on the calculated average SOC value for the entire battery bank regardless of the selected option.
Voltage control
The battery bank starts to charge at specified voltage levels. The charging stops when a specified voltage level is reached and the charge current falls below a specified value. The method does not take into account the state of charge.
Used in applications where no communication is available or when SOC is not of interest. The use of batteries is not optimized.
Static state of charge
The batteries start and stop charging at predefined SOC levels. The SOC values for starting and stopping charge cycles are configurable and can be changed in the local web pages.
Used with battery bank delivered with proper data. Static SOC gives a good estimation of battery life-time. Use of batteries is optimized with data from the internal BMS of the batteries.
8.4.2.4 Synchronize step
For battery banks with apparent propagating unbalance during charge cycles, a synchronization step at the end of each charge cycle can be enabled, where the BMUs are allowed to synchronize internally under a period of no or very low charge current. This final balancing touch is best performed while charging at the top of the charge cycle when internal voltage differences in the bank are more apparent and internal cell resistances are minimized. The charge current limit and the duration of this period are both configurable.
8.4.2.5 Balancing Full Charge
As a complement to regular charge cycles in hybrid operation for Li-ion batteries, optional full charge cycles, here labelled Balancing Full Charge cycles, are supported by eSite x10. They are slightly different from the Full Charge cycles used for lead-acid batteries, where maintained charge current for long periods of time is necessary for ensuring good battery performance. Li-ion batteries are less sensitive to damage from partially charging the battery bank than lead-acid batteries, and do not have the same need to repeatedly be fully charged. Indeed, it can be argued that fully charging Li-ion batteries to a large extent should be avoided in order to not risk overcharging the batteries, which may cause damage. However, for a newly installed or a severely unbalanced battery bank, it might be necessary to perform a full charge cycle to reach the very top of the battery voltage/SOC characteristic and achieve appropriate balance within the bank.
Balancing Full Charge cycles are available, and will work in the same way, for both the Li-ion VC and SSOC strategies. For the SSOC strategy, a configurable safety voltage level has been introduced that will trigger a Balancing Full Charge cycle in any faulty scenario where the SOC cannot be reported or calculated correctly. This voltage level should be set to a higher value than the LP load LVD voltage level as a precaution to prevent LVD.
A Balancing Full Charge cycle can also be triggered manually via a command from the eSite Web Battery tab.
If desired, periodic Balancing Full Charge cycles may be enabled. When enabled, Balancing Full Charge cycles will be triggered automatically based on intervals of either accumulated energy throughput from the battery bank or number of completed regular charge cycles, whichever occurs first. Both interval parameters are configurable.
A Balancing Full Charge cycle is completed when the battery voltage has exceeded the BMS Fully charged voltage level and the charge current has fallen below the battery cut-off level specified by the manufacturer. After a Balancing Full Charge cycle is completed, it is followed by a mandatory Synchronize step before AC power is turned off. Upon completion, the periodic intervals for energy throughput and number or cycles are both reset.
8.4.2.6 Charge Mode
The active charge mode is presented under the Battery tab on eSite Web and in eSite Tools.
For handling of Li-ion batteries, one of the following charge modes is used.
Ramp Up: The battery bank is in the Precharge state and the system is slowly ramping up the voltage to avoid initial inrush currents.
Normal Charge: Normal hybrid operation is active. The battery bank is charged/discharged according to the selected charge strategy.
Synchronize: Synchronization of the BMUs in the battery bank is active. The battery bank is forced into the Equilibrium state and is not charged/discharged.
Balancing Full Charge: The battery bank is currently being charged in a Balancing Full Charge cycle. The system will be in Auto Full Charge mode.
Safe Mode: eSite x10 is currently in Safe Mode and cannot determine the correct state of the battery bank. Maximum allowed charge current and set voltages are lowered to protect the system.
8.4.2.7 Hybrid Shifting
The purpose of Hybrid Shifting (HS) is to increase solar production efficiency on hybrid sites during the day by having a lower SOC in the morning and thus have more solar energy captured in the batteries. The simple concept of hybrid shifting is to split a day into 2 periods where the DG stop voltage differs.
Note
Hybrid Shifting function is only valid for lithium-ion batteries configured to run in the 'Voltage Control' charge strategy.
Example:
3:00-09:00
54.0V
09:00-2:59
56.5V
The configurable parameters can be set via local Web, eSite Tools and SNMP. See Battery section for details how to configure the feature.
8.4.2.8 Peak Load Shifting
The purpose of Peak Load Shifting (PLS) is to maximize the solar energy for on-grid sites where the grid is available and stable. The idea behind the feature is to:
Power the site load and if possible, charge the Li-ion battery bank during daytime from the solar panels.
At a configurable time (PLS_end_time) the grid should be used to charge the battery bank to adjustable Vmax (normally set to float voltage) at full power.
During the night, the grid will be used to power the load and keep the battery bank at Vmax, normally at float voltage.
At a predetermined and configurable time (PLS_start_time), the AC rectification should be inhibited, and the battery bank will power the load until the battery bank voltage has reached an adjustable voltage setpoint (PLS_Voltage).
Grid will maintain the battery bank at a predetermined voltage level(PLS_Voltage) if solar power is not sufficient to carry the site load.
If grid becomes unavailable and battery bank reaches the DG start voltage, the genset will start. At this point, PLS functionality will be suspended and Hybrid Shifting will take over until the batteries reach the DG stop voltage and until DG is turned off again.
Note
Peak Load Shifting function is only valid for lithium-ion batteries.
Example:
3:00-09:00
54.0V
09:00-2:59
56.5V
The configuration parameters can be set via local Web, eSite Tools and SNMP. See Battery section for details how to configure the feature.
Note
Note that the Hybrid Shifting and the Peak Load Shifting parameters must be configured separately.
Below graphs shows the different power sources and different event scenarios.
Normal operation 1
During nighttime grid powers the load and SOC/Vbatt is maintained at Vmax. At PLS_start_time, grid power is switched off and battery discharges until PLS_Voltage has been reached. At this time, grid will power the load again and solar will charge battery bank if solar power is above load power. If solar power is below load power, grid will support so that SOC/Vbatt is kept at PLS_Voltage (Solar power + grid power = load power). At PLS_end_time grid will charge the battery bank until Vmax has been reached.
Normal operation 2
During nighttime grid powers the load and SOC/Vbatt is maintained at Vmax. At PLS_start_time, grid power is switched off and battery discharges until time PLS_Voltage has been reached and grid will power the load to keep SOC/Vbatt at PLS_Voltage. Solar will charge the battery bank if the solar power is above the load power. If the solar power is below the load power, grid will support so that SOC/Vbatt is kept at PLS_Voltage (Solar power + grid power = load power). At PLS_end_time, grid will charge the battery bank until Vmax has been reached.
Grid lost during daytime
In this scenario grid is lost during daytime and system reverts to Hybrid shifting mode instead. When grid is lost, SOC/Vbatt will drop until DG start is reached. The Genset will charge the battery bank but since the time is past Time HS1 (Hybrid Shifting time 1), Genset will charge the bank until DG stop HS1 has been reached. At sunset, the SOChas again dropped to DG start but, in this case, the Genset will charge the battery bank up to DG stop HS2 since time has passed Time HS2.
Grid lost during Genset charging
In scenario 4, grid is lost in the morning and the system reverts to Hybrid shifting mode instead. When grid is lost, SOC/Vbatt will drop until DG start is reached. The Genset will charge the battery bank but during charge, grid becomes available again and eSite x10 will shift to Grid and finalize the charge sequence until DG Stop HS1 has been reached (since time has passed Time HS1). When charge cycle has been completed, PLS mode will become active again.
8.5 Genset
Read
Always follow the genset manufacturer's instructions during work with the genset.
eSite x10 automatically starts and stops the genset when requested by the selected battery charge strategy, voltage level or set time. The genset start signal is controlled by a relay that is closed when eSite requires the genset to start. The output relay can be configurable via the local eSite Web.
eSite x10 determines the genset power request and controls the genset power output so that it is not overloaded. This can be used to prevent overload on smaller gensets.
8.5.1 Genset modes
Ready. Genset is ready to start, waiting for a charge request.
Start request. Genset is requested to start. It stays in this mode until eSite sense voltage.
Warm up. Warming up genset without any power request.
Ramp up. The requested power is linearly ramping up.
Running. Genset is providing power.
Ramp down. Genset is ramping down.
Cool down. Genset is running in idle without any power output.
Off state. Waiting for the genset to turn off. The state is active until the genset has stopped or 5 min has passed.
The times for genset warm up, ramp up/down and cool-down can be configured.
Note
Always configure the genset according to the genset manufacturer recommendations. This extends the genset lifetime.
8.5.2 Genset communication
Dry contacts. eSite x10 has 3 available input relays for each genset, when triggered an alarm activates. The input relays can be configured as normally open, normally closed or not used.
Modbus. eSite x10 can communicate with the genset to read signals and alarms directly from the genset AMF panel. The supported protocol is Modbus-RTU. Configuration for different genset panels can be customized on site or a premade configuration set can be created upon request. The data and alarms that are retrieved from the genset panel are stored and logged, both locally and remotely, every 10 minutes.
Note
The AMF panel communication over RS485 (Modbus-RTU) can not be used if the RS-485 port is already occupied by either by the Modbus server.
8.5.3 Dual Genset
eSite x10 supports operation with two connected gensets. Only one genset at a time can deliver power to the system. In regular hybrid operation, eSite x10 alternates the charge cycles between the two gensets. If one genset fails during operation, the other genset is immediately commanded to start.
For example:
Genset 1 fails during a charge cycle.
The start command to genset 1 stops. Genset 2 is commanded to start and completes the charge cycle.
Next charge cycle starts with genset 1. If genset 1 does not start, genset 2 will be commanded to start.
8.5.4 Genset runtime and service
eSite x10 can keep track of the total runtime and the remaining time (hours) until genset service is required. The service interval and when the alarm is triggered can be configured. Total runtime can be reset manually.
8.5.5 Estimated time to Genset start
When Static SOC or Partial SOC charge strategy is selected, eSite x10 estimates the time until the genset starts to operate. The estimation is based on the discharge current and the low SOC threshold level where the charge cycle starts.
8.5.6 Night Silence
Caution
Night Silence mode prevents the genset from running at night. This can have a negative impact on battery health and site performance and void the battery warranties.
The Night Silence period start time can be configured. eSite x10 can pre-charge the battery bank to ensure that it is sufficiently charged when the Night Silence period starts. The end of the period can be configured to end by time, voltage or SOC, whichever occurs first. Outside the period the configured charge strategy is used.
Night Silence mode is used for both off- and on grid sites. For on grid sites pre-charge is usually not required. If the grid fails during the silent period the configuration determines when the genset is allowed to start.
When Night Silence is inactive or disabled, charge cycles are performed without interference.
8.5.6.1 Night Silence pre-charge
The Night Silence pre-charge function charges the battery bank to a state where its autonomy time fulfils the Night Silence period. The function calculates the required number of ampere-hours (Ah) required for battery autonomy time based on the present site load and the number of hours of the silence period.
The following formula is the estimate of the preceding charge time in hours where Autonomy Ampere Hours is the needed energy required by the batteries for the duration of the Night Silence period. Safety margin is a configured threshold for the energy level that battery bank should be at in the end of the period. Present battery capacity is the capacity of the battery dynamically calculated, and the max charge current is the max allowed charge current.
8.5.6.2 Night Silence active
For Night Silence to accurately shut off the genset at the configured time the site utilizes Network Time Protocol (NTP) time synchronization or is synchronized from eSite Tools. A local time zone must be configured at each site.
During the active period the genset is not commanded to start. The tenant receives power as long as the Low Voltage Disconnect is not triggered. The configurations are usually set for the active period to be aborted before this happens. To manually force the genset to start overrides the Night Silence and allows the genset to start.
8.5.6.3 Night Silence aborted
The Night Silence period can be stopped before the stop time is reached to allow the genset to start.
8.5.6.4 Stop on charge request
If the stop on charge request configuration is ON, Night Silence is stopped when a charge request is triggered by the charge strategy. This configuration is usually used when the pre-charge cycle is desired to prepare the batteries for the night but standard charge strategy still is used.
A charge request always starts the genset if grid or solar is not available. A full charge cycle triggered by time or energy is postponed until the end of the Night Silence period. A full charge cycle not triggered by time or energy aborts the Night Silence period regardless if it was triggered during or before the Night Silence period.
8.5.6.5 Do not stop on charge request
If stop on charge request is OFF, the Night Silence period is aborted by a voltage level or a SoC level, whichever occurs first. A deeper discharge than intended by the charge strategy can be achieved to prolong the silent period. The values can be set below the Low Voltage Disconnect threshold.
8.6 Solar
Three (3) internal solar converters and two (2) external solar converters can be utilized by the eSite x10. The internal solar converters require no configuration and use an MPPT (maximum power point tracking) technology to ensure that the harvested solar power is maximized continuously. Any external solar converters must be separately connected and enabled in configurations.
If the solar array is incorrectly connected, for example with reversed polarity, an alarm becomes active and a relay disconnects the solar array to protect the eSite x10 system.
The eSite x10 internal solar converters are designed for use with mono-crystalline and polycrystalline solar panels with 72 cells and 6 inch wafers. An optimal solar array is easily configured with these types of panels. It is also possible to use panels with other number of cells.
Caution
Do not connect solar panels with built-in electronics to eSite x10. Contact eSite Power Systems for further information regarding this.
Open circuit voltage of each string of solar panels must never exceed 140 V.
The total of solar array current never exceeds 20 A per solar converter. Additional panels are not harmful to the eSite x10, but might not be utilized optimally.
8.6.1 Green Power Influx
The Green Power Influx (GPI) component maximizes solar energy harvesting in relation to other power sources. When sufficient solar power is available, GPI becomes active and power drawn from the genset(s) and grid is inhibited.
Activation of the GPI functionality depends on the following conditions:
Green Power mode must be enabled.
Solar Power is sufficient.
Battery state of charge (SOC) is sufficient.
Batteries are in Normal charge mode and voltage is above limit.
System voltage is above limit.
Specified time interval (if applied).
Solar power is sufficient when it holds a configurable percentage of the load. To avoid frequent start and stop of the genset in case the solar power fluctuates, a delay timer for entering and exiting GPI is used to make sure that the solar power is sufficient and stable. This delay timer can be configured.
To ensure that the backup time is sufficient in case of a genset or Grid failure, the battery bank must be above certain SOC and voltage threshold levels before GPI is activated. These thresholds are configurable, see Solar section for details how to configure the feature.
The GPI function is always in one of the following states:
Disabled. GPI is disabled (default)
Inactive. GPI is enabled by the user, but the solar power is insufficient or eSite x10 is currently in Safe mode.
Stopped. Solar power is sufficient, but the battery voltage or SOC is too low.
Idle. The solar power has not reached the selected load percent activation level (Load Percent operational mode), or current time is outside the selected time interval (Time Interval operational mode).
Active. All conditions are fulfilled, genset(s) and Grid are inhibited and the Solar power is fully utilized.
Green Power Influx has three (3) operational modes to choose from when activated: Load Percent operational mode (default) see section "Load Percent operational mode", Time Interval operational mode section "Time Interval operational mode" and "Maximum Solar Power in Good Grid (AC Power Minimization)"
8.6.1.1 Load Percent operational mode
Load Percent operational mode is the default mode for GPI. This mode is suitable for all AC source configurations and when active, it inhibits both Grid and genset from running.
In Load Percent operational mode, GPI is activated and the AC sources are switched off at a predetermined percentage of Solar power with respect to the customer load. AC power remains inhibited as long as the Solar power is sufficient. When the Solar power drops to a certain percentage level of the customer load, GPI is deactivated and AC power is allowed again to continue charging of the batteries.
If a genset is connected to the eSite x10, an example of a typical GPI application scenario is given in the next figure.
For the example above, the Solar Load activation threshold is set to 80 % of the customer load and the deactivation threshold is set to 70 % of the customer load. If the Grid is the primary AC source, the GPI component switches off and reengages the grid at predetermined percentage levels of solar power with respect to the customer load.
8.6.1.2 Time Interval operational mode
In Time Interval operational mode, specified times are set to enable/disable the AC source(s) according to when the Solar power is expected to be sufficient to run the customer load. The start/stop times of this function are configurable.
The Time Interval operational mode is mainly intended for use on sites with reliable Grid connections and high Solar output during daytime. When the purpose is to disable the genset from running in a specified time interval, it is recommended to use the Night Silence function instead.
Thus, in a typical application scenario for an on-grid site with good Grid quality, the customer can choose a disable time where the Grid should be disabled and an enable time for the site to re-enable the Grid. An example is given in the next figure.
This time interval example shows a Grid disable time at 05:00 and a re-enable time at 18:30.
8.6.1.3 Maximum Solar Power in Good Grid
This feature covers the need to minimize the energy used from the Grid on telecom sites where there is a substantial amount of installed Solar power, and hence maximize the use of installed Solar power capacity.
The aim is to use as much Solar energy as possible during the daytime to support both the telecom load and at the same time charge the battery bank. To be able to partly charge the bank, this feature is preferably applicable to Li-ion battery banks.
Power the site load and charge the Li-ion battery during daytime via the solar panels.
Power the site load by the battery bank when there is no solar available.
If the battery bank has reached a low predetermined SOC level (called SOCmin) during night, the grid will be used to power the telecom load only.
If the Grid becomes unavailable, the genset will be used to power the load.
Normal Operation
The battery bank will power the load after sunset and when the SOC has reached the SOCmin, the grid must supply the load during a portion of the nighttime. There is a load decrease/increase during night and hence power from grid will follow accordingly. SOC is maintained at SOCmin during night.
Grid loss during night
In this scenario, the grid is lost during night and the genset will be started to power the load until the solar power is enough to carry the telecom load.
Both grid and genset lost during night
The grid is lost during night and the genset fails to start after several start attempts. SOC will drop to SOClvd level and the eSite x10 will do a low voltage disconnect, hence dropping loads. Note that this will be in two steps, first disconnect of low priority load and later high priority load, this is not shown in the graph.
The telecom load will be lost until the grid is available again. Grid will be used at maximum power to charge the battery bank up to SOCmin level and then be lowered to just power the load and keeping SOC level at SOCmin until the solar power can power the telecom load.
Note that if the genset suddenly is operational again during low voltage disconnect, maximum power will be used from genset in order to bring the SOC up to SOCmin level.
Solar power only
In this case, solar can power the load without use of AC power.
8.6.2 External Solar
In addition to the capacity of the internal solar converters, the eSite x10 supports a maximum of two (2) external solar converters that can be connected to the system. External solar converters operate independently and are not controlled by the eSite x10 system. A current sensor must be connected to each external converter to measure the added current to the system. The added current is taken into consideration by the eSite x10 in its regulation of internal converters. The CAN connected sensors are configured in the Solar web pages. Contact eSite Power systems for detailed installation instructions.
8.7 Grid
Grid control is the collection of settings that monitors and manages the power extraction of a connected grid. Depending on the quality of the grid, the system uses different modes of operation for optimal performance. The system is designed for a three-phase grid connection, but is also capable of handling single phase connections.
Each rectifier measures voltage and frequency independently. If a phase is invalid, the other rectifiers continues to operate with the valid phases. A phase is valid inside these ranges:
Voltage active range 85 – 300 Hz.
Frequency active range 45 – 65 Hz.
Outside these ranges, the rectifiers are disabled.
The performance of the rectifiers is monitored and presented as Grid status:
Invalid. All rectifiers are disabled due to insufficient phase voltage and/or frequency. Grid is not available.
Inhibited. Grid is available on at least one phase, but all rectifiers are inhibited from running and no power from grid is extracted. This state is entered when GPI is active or when the genset is prioritized to run, e.g. with an active Exercise Run request or when the genset is forced on.
Partial. One or two phases are valid, the rectifiers are active and running. Grid is partially available.
Ok. All three phases are valid, the rectifiers are active and running. Grid is available.
Power extraction from grid is limited by the size of the grid fuse. This value can be configured to ensure the fuse is not tripped and overloaded. Power extraction also adapts to the available grid voltage and classifies the quality of the grid according to the following:
No grid (< 85 V)
Bad grid (85 – 200 V)
Good grid (> 200 V)
Good Grid
In Good grid mode, the rectifier is requested to extract the maximum possible power, 3 500 W, from the grid. The maximum possible power can be configured.
If the grid is of low quality, set a lower grid fuse rating.
When entering Good grid mode from Bad grid mode, the rectifier rapidly ramps up the current to the maximum level.
Bad Grid
If the grid is active but the voltage is less than the Good grid threshold (200 V), the grid is considered bad. The rectifier power extraction employs a dynamic strategy to extract power from the grid, with the aim of finding a stable state where the maximum possible power is extracted. The software sets the rectifier current, and thereby the power request, based on the grid voltage at any given time, continuously running the following steps:
If the grid voltage increases or remains unchanged, the rectifier current, and thereby the power request, is increased in small increments.
If the voltage decreases, the current is also decreased for stabilization purposes.
This process is active until the rectifier finds a stable point where the maximum power is extracted for the given voltage or until the grid enters Good grid mode.
8.8 UPS AC mode
As an alternative to regular hybrid operation, the eSite x10 can be set into an 'uninterruptible power supply' (UPS) state, where AC power is being utilized constantly. The main purpose of the UPS AC mode is to always keep the site on-line and the batteries fully charged. This application is mainly intended for use on sites with poor-quality batteries that cannot be relied upon to carry the customer load for any for any length of time. The battery bank will always be in the Charge state regardless of SOC and charge current, and will normally be kept at float voltage. Periodic or singular Full Charge cycles at boost voltage can be activated via configuration.
For site configurations with one AC source, i.e. a single genset or grid only, activation of this feature simply means that the available AC source will always be commanded to deliver power to the site.
As in normal hybrid operation, DC solar power may be utilized at all times in conjunction with the AC source(s). However, the Green Power Influx and Genset Night Silence features are not compatible with UPS AC mode and shall be disabled.
For grid/genset site configurations, AC power from either grid or genset may be utilized in UPS AC mode, with grid having higher priority than the genset. If one AC source fails, the second source is immediately commanded to start delivering power to the site.
For dual genset site configurations, equal run time of the two gensets is achieved by regularly switching between the gensets based on a timer. Both gensets are requested to run before switching source to ensure minimum downtime. If one genset fails while running, an alarm is triggered and a start request to the second genset is commanded. The time to detect malfunction and activate the alarm is configurable with the "Genset start alarm delay time" parameter. See section Genset configuration for more information.
All UPS AC mode configuration parameters have to be set in order to activate UPS AC mode, see section Battery configuration.
8.9 Load Disconnect
The eSite x10 is equipped with dual Load Disconnect breakers that are controlled automatically. This makes it possible to divide the customer load into two parts of different priority, a low priority (LP) part and a high priority (HP) part. In any faulty scenario where the system due to a major malfunction, such as the AC genset not being able to start, is unable to properly support the load and charge the battery bank, the system is eventually protected by tripping the breakers, disconnecting the load.
In such a scenario, the low priority (LP) customer load may be chosen to disconnect before the high priority (HP) load. The HP load is generally intended to be of smaller size than the LP load. Check the data sheet for current limitations of HP and LP loads.
This functionality is designed to keep the site online for as long as possible and to protect the health of the batteries.
8.9.1 Low Voltage Disconnect (LVD)
The customer load is disconnected if incoming power is unavailable and the battery voltage falls below a configurable voltage threshold for a specified time (also configurable).
By disconnecting the customer load at low voltage levels, the battery bank is prevented from completely discharging. However, the delay timer makes it possible to handle sudden voltage drops upon engaging loads, i.e. if a load is engaged and the voltage drops below the defined threshold.
All LVD parameters are configurable, see section Low voltage disconnect settings.
8.9.1.1 LP Load LVD
When the system voltage falls below the threshold Low Prio load disconnect volt , the LP load will be disconnected after a Low Prio load disconnect time . An alarm for LP load LVD will be triggered.
When incoming power is available again, the battery voltage recovers to the Low Prio load reconnect volt threshold and the total delivered current exceeds the Low Prio load reconnect current threshold (default 20 A), a timer will start and the load will be reconnected after a short Low Prio load reconnect time .
For a quick recovery with a rapid increase to high voltage levels, the load may also be reconnected when the battery voltage exceeds the Low Prio load fast reconnect load . threshold without any delay.
8.9.1.2 HP Load LVD
HP load LVD functionality is disabled by default, but can be enabled with the High Prio load LVD enable setting. When this functionality is enabled, separate LVD settings (also configurable) for the HP load will be used.
If HP load LVD is disabled, the HP load will be disconnected and reconnected with the same settings as for the LP load LVD.
If HP load functionality is enabled and the HP load gets disconnected before the LP load, e.g. in case of a rapid voltage decrease, this will also trigger an LP load disconnect. Typically, the HP LVD has a lower voltage disconnect level but a shorter disconnect time. This will prevent the LP load from continuing to discharge the batteries.
8.9.1.3 Overcurrent Load Disconnect
The LVD breakers are protected by an internal system function that disconnects the load if the LP or HP current exceeds 200 A. If this occurs, an Alarm is also triggered. The system will automatically try to reconnect the load 5 times with 20 second intervals.
If the system does not succeed to reconnect, there is a Reset Load switch button on the eSite Eeb pages. Pressing this button will reset the LVD breakers and reconnect the load. It is also possible to undock the main compartment to reset the LVD breakers.
8.9.2 Multi tenant monitoring
The eSite x10 supports monitoring of up to six (6) tenants separately. The total consumed load, including both HP and LP loads, is measured and logged. Auxiliary equipment on site is not included.
The sensors shall be connected via CAN, see detailed info in the Tenant Configurations.
8.10 Cabinet Cooling
eSite x10 has a feature able to control, i.e. turn on/off, an external cooling device connected to a digital output port. The device is controlled with a relay based on the readings from the temperature sensors.
This feature can be used to control the temperature in the battery cabinet to further extend the battery lifetime in areas where appropriate battery temperature is not guaranteed by the site environmental conditions.
The Ambient temperature sensor and the Battery temperature sensors are both required by the Cabinet Cooling feature. If any of the sensors becomes invalid while the feature is activated, the feature will be in "Fallback" mode and the output will be ON.
The Digital output relay shall be configured to one of the standard output relays on the I/O board. See the I/O Configuration page.
The feature can be set into two different modes: Delta Ambient mode, which is based on the temperature difference between the battery and ambient temperatures, and Battery Temperature mode, which uses absolute temperature levels to start/stop cooling.
All configurations can be done in local web pages, see Cabinet Cooling setup.
8.11 Fuel monitoring
The Fuel Monitoring functionality gives the customer detailed information about the fuel level, consumption and abnormal events. Volume level, consumed, filled and lost volume is tracked and logged. The fuel monitoring makes it easier to plan when to refill fuel.
The fuel monitoring sensor is connected to the analogue input 0 – 10 V and receives power from the 24 V output. Two fuel sensors can be connected at the same time in order to monitor two separate tanks.
Filled and lost volume is calculated when a volume change has been detected. A volume change is triggered when the volume changes rapidly. This is configured as a percentage of the total tank volume / time span. Default is 4 % / 30 min.
The thresholds for low and very low fuel level alarms are configurable. Sensor out of range alarm is triggered when the voltage output of the sensor is outside its configured range.
Connect fuel sensor 1 to Analogue in 2+ and Analogue in 2- Connect fuel sensor 2 to Analogue in 3+ and Analogue in 3-
8.12 Communication interfaces
8.12.1 Modbus Server
A Modbus server can be started via the local eSite Web configurations. eSite x10 support Modbus-RTU and Modbus-TCP. A complete register with all signals specified can be requested from eSite Power Systems.
Note
The Modbus server over RS-485 (Modbus-RTU) can not be used if the RS-485 port is already occupied by either by Li-ion communication or AMP panel communication.
8.12.2 SNMP
The eSite x10 provides support for SNMP communication. A complete MIB with all signals specified can be requested from eSite Power Systems.
8.12.3 CAN
The eSite x10 supports communication via the CAN protocol and can be used with e.g. Li-ion batteries or external LEM current sensors.
The eSite x10 software also supports joint operation with one (1) additional connected eSite x10 unit. Connecting an additional eSite x10 unit will increase the maximum rectifier power of the system to 21 kW. One unit will act as the Master unit and the other as the Expansion unit. All decisions and controls are processed in the Master unit. Communication between the Master and Expansion units is handled with the CAN protocol. The rectifiers in the Expansion unit are connected to the same phase and receive the same control signals as their counterpart in the Master unit, i.e. rectifiers 1 & 4, 2 & 5, and 3 & 6 are synchronized. Alarms and Errors are presented on the Master unit web pages and on eSite Tools. The customer loads can be connected to a common bus bar or separately to each unit.
At least one external battery sensor has to be mounted on a system with an Expansion unit connected. Configurations are made at the web pages.
Contact eSite Power Systems for more information of how to install and configure a site with an Expansion unit.
8.12.4 I/O screw terminals
The table shows the pin descriptions and the default configurations for the I/O screw terminals on the RSY and RSC models. The digital inputs can be configured to normally open or normally closed.
Model: RSY (Serial number: 7246XXX)
Model: RSC (Serial number: 7247XXX)
*connected from factory.
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