Download Theory of Operation

Pentadyne Voltage Support Solution™
Theory of Operation
Pentadyne VSS
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Table of Contents
1.
SYSTEM OVERVIEW .................................................................................................................................. 4
1.1.
GENERAL SYSTEM DESCRIPTION .............................................................................................................. 4
1.2.
POWER SYSTEM ........................................................................................................................................ 5
1.3.
PERFORMANCE.......................................................................................................................................... 6
1.4.
APPLICATION FLEXIBILITY ....................................................................................................................... 7
1.4.1.
Ride-through protection .................................................................................................................. 7
1.4.2.
Ride-through to generator............................................................................................................... 7
1.4.3.
Battery life extension/energy storage redundancy .......................................................................... 8
2.
DETAILED SYSTEM DESCRIPTION........................................................................................................ 8
2.1.
USER INTERFACE....................................................................................................................................... 8
2.1.1.
Control Panel .................................................................................................................................. 8
2.1.2.
Data Collection Module (DCM)...................................................................................................... 8
2.1.3.
Versatile Interface Board (VIB) ...................................................................................................... 8
2.2.
UPS INTERCONNECTION KIT..................................................................................................................... 9
2.3.
MAGNETIC LEVITATION MODULE (MLM)................................................................................................ 9
2.4.
POWER CONVERSION MODULE (PCM) ................................................................................................... 10
2.4.1.
Power Conversion Module Controller (PCMC)............................................................................ 10
2.4.2.
IGBT Power Conversion ............................................................................................................... 10
2.5.
FLYWHEEL MODULE ............................................................................................................................... 11
2.5.1.
Rotor/Flywheel (Rotating Group) ................................................................................................. 12
2.5.2.
Motor-Generator ........................................................................................................................... 12
2.5.3.
Vacuum System.............................................................................................................................. 13
2.5.4.
Flywheel Sensors........................................................................................................................... 13
2.5.5.
Active Magnetic Levitation Hardware .......................................................................................... 14
2.5.6.
System Safety ................................................................................................................................. 14
2.6.
CABINET ................................................................................................................................................. 15
2.7.
VENTILATION AND COOLING .................................................................................................................. 15
3.
SYSTEM CONFIGURATION .................................................................................................................... 16
3.1.
MODES OF OPERATION ........................................................................................................................... 16
3.1.1.
OFF Mode ..................................................................................................................................... 18
3.1.2.
STARTUP Mode ............................................................................................................................ 18
3.1.3.
CHARGE Mode ............................................................................................................................. 18
3.1.4.
READY Mode ................................................................................................................................ 18
3.1.5.
DISCHARGE Mode....................................................................................................................... 19
3.1.6.
SHUTDOWN Mode ....................................................................................................................... 19
3.1.7.
COAST Mode................................................................................................................................. 19
3.1.8.
FAULT Mode................................................................................................................................. 19
3.2.
USER-CONFIGURABLE SYSTEM PARAMETERS ......................................................................................... 20
3.2.1.
Charge Voltage (Vcharge) ............................................................................................................ 20
3.2.2.
Regulation Voltage (Vreg)............................................................................................................. 20
3.2.3.
Regulation Voltage Droop During Discharge (Vreg Delta).......................................................... 20
3.2.4.
Maximum Charge Current (Max Charge Current) ....................................................................... 20
3.2.5.
Charge Conductance (Charge Amps/Volts) .................................................................................. 20
4.
MAINTENANCE & RELIABILITY .......................................................................................................... 21
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Table of Figures
FIGURE 1 - VSS+DC CABINET LAYOUT ........................................................................................................................ 4
FIGURE 2 - SCHEMATIC OF THE ELECTRICAL SYSTEM ................................................................................................. 5
FIGURE 3 - PERFORMANCE CHART ............................................................................................................................. 6
FIGURE 4 - MULTI-UNIT INSTALLATION – RIDE THROUGH PROTECTION ..................................................................... 7
FIGURE 5 - MULTI-UNIT INSTALLATION WITH GENERATOR FOR CONTINUOUS PROTECTION ........................................ 7
FIGURE 6 - MULTI-UNIT INSTALLATION WITH BATTERIES IN PARALLEL...................................................................... 8
FIGURE 7 - SCHEMATIC OF THE LEVITATION SYSTEM. .............................................................................................. 10
FIGURE 8 - FLYWHEEL MODULE ............................................................................................................................... 11
FIGURE 9 - ROTATING GROUP .................................................................................................................................. 12
FIGURE 10 - CROSS-SECTION OF THE SYNCHRONOUS RELUCTANCE MOTOR ROTOR .................................................. 12
FIGURE 11 - VACUUM SYSTEM OPERATION............................................................................................................... 13
FIGURE 12 - SCHEMATIC FOR THE SPEED AND TEMPERATURE SENSORS .................................................................... 14
FIGURE 13 - CUTAWAY FLYWHEEL MODULE ........................................................................................................... 15
FIGURE 14 - TYPICAL MODES OF OPERATION ........................................................................................................... 17
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1. System Overview
1.1. General System Description
The Pentadyne Voltage Support Solution™ is a flywheel-based energy storage system. It operates
as a mechanical battery that stores energy in the form of a rotating mass. This energy is immediately
converted to useful power when needed.
The VSS+DC is configured as a two-terminal DC system and is used as a functional replacement for
a bank of chemical batteries used with Uninterruptible Power Supply Systems (UPSs). In addition,
the VSS+DC can work in parallel with a bank of chemical batteries for increased DC bus reliability
and redundancy. As with a chemical battery bank, it receives recharge and float power from the
two-terminal DC bus and returns power to the same DC bus whenever the voltage droops below a
programmable threshold level. Multiple VSS+DC units can be put in parallel for higher power output,
longer ride-through duration and/or redundancy. The VSS+DC can be used in many DC applications
to provide power quality or energy recycling. The VSS+DC is designed not to require major service for
20 years in a UPS application.
Figure 1 - VSS+DC cabinet layout
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1.2. Power System
The electrical system of the VSS+DC is illustrated in Figure 2, the schematic shows the Magnetic
Levitation Module (2.3). The pre-charge resistor and contactor which limit the inrush current into the
DC bus capacitors. The six-pulse IGBT power converter (2.4.2) is controlled by the Power
Conversion Module Controller (2.4.1) which also monitors and controls the operation of the entire
system. These components are housed within the Power Conversion Module (2.4). The Flywheel
Module (2.5) is shown as a cross section illustrating the rotating group and the synchronous
reluctance motor-generator.
Figure 2 - Schematic of the electrical system
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1.3. Performance
The maximum output power of the VSS+DC is dependant upon the duration required. This is illustrated
in Figure 3 below. Increased power, duration and/or redundancy can be achieved by adding units in
parallel.
Figure 3 - Performance Chart
*kWb = Refers to Kilowatts on the DC bus of the UPS system.
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1.4. Application Flexibility
1.4.1. Brief ride-through protection
Figure 4 illustrates three or more units connected to a UPS to provide ride-through protection.
This system architecture is most often used for glitch protection in industrial process plants.
Figure 4 - Multi-unit installation – Short-term ride-through protection
1.4.2. Ride-through to generator
Figure 5 illustrates the system architecture if continuous power protection is required in the
event of an extended power outage.
Figure 5 - Multi-unit installation with generator for continuous protection
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1.4.3. Battery life extension/energy storage redundancy
Figure 6 illustrates an installation with VSS+DC units and batteries connected in parallel.
Connecting the system in this way extends the life of the batteries because the VSS+DC units
support all glitches and all backup genset ridethrough events, isolating the batteries from use.
Figure 6 - Multi-unit installation with batteries in parallel.
2. Detailed System Description
2.1. User interface
2.1.1. Control Panel
The VSS+DC uses an LCD control panel as the primary means for an operator to interface with
the system. Operating parameter values are displayed and updated in real time, as are alarm
states, system notices and event logging. User configurable system parameters are adjusted
via the control panel. Information is located using the menu-based structure. Several layers of
security access are included.
2.1.2. Data Collection Module (DCM)
An optional software and hardware package that reads data from the VSS+DC. The data is
stored and then can be transmitted through an RS-232 port, over a LAN (Local Area Network)
or over the Internet, enabling PC-based diagnostic reporting capability onsite or remote.
2.1.3. Versatile Interface Board (VIB)
An optional software and hardware package is available that allows for remote monitoring and
control; via isolated auxiliary dry contacts:
•
•
•
•
•
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OFF Mode
STARTUP Mode
CHARGE Mode
State of Charge (SOC) ≥ 0%
State of Charge (SOC) ≥ 12.5%
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•
•
•
•
•
•
•
•
•
•
•
•
State of Charge (SOC) ≥ 25%
State of Charge (SOC) ≥ 37.5%
State of Charge (SOC) ≥ 50%
State of Charge (SOC) ≥ 62.5%
State of Charge (SOC) ≥ 75%
State of Charge (SOC) ≥ 87.5%
State of Charge (SOC) ≥ 100%
DISCHARGE Mode
SHUTDOWN Mode
WARNING Mode
FAULT mode
Motor Hot Standby
Control commands:
• Startup
• Shutdown
• Clear Fault
2.2. UPS Interconnection Kit
The UPS Interconnection Kit (IKit) is a module that simplifies interconnection with a UPS system.
There are several versions of the IKit available that have been developed through VSS+DC
integration testing with several types of UPS systems. The VSS+DC (standard configuration) is
delivered with an IKit consisting of a fused power terminal block for connection of the positive and
negative terminals of the UPS DC bus or of an external disconnect switch.
2.3. Magnetic Levitation Module (MLM)
The magnetic levitation module provides control of the active magnetic levitation hardware.
The VSS+DC has a unique, patented active magnetic levitation system that fully levitates the
flywheel-rotating group, allowing the flywheel to rotate without any physical contact. This has a
number of advantages over mechanical bearing systems:
A. Reduced drag: Mechanical bearings induce drag proportional to the square of the speed. The
levitation system developed by Pentadyne uses the same power regardless of speed, one of
the primary reasons that Pentadyne flywheels use only one-tenth of the standby energy of
other commercial flywheel products, saving the end-user thousands of dollars in annual utility
charges for each unit deployed.
B. Maintenance-free reliability: The levitation system ensures there is no contact between the
rotating parts and the housing and therefore there are no components to wear out. This
ensures the unit will operate maintenance free for the life of the system. Other flywheel systems
require bearing replacement every 2-3 years that incur 4-8 hours of downtime and costs
thousands of dollars.
The levitation system works by measuring the displacement using a capacitive sensor. If the
distance needs to be adjusted, current to the electromagnet is altered to change the displacement,
each axis is measured and controlled separately with its own capacitive sensor, electromagnet and
feedback loop, which is controlled by the MLM. This is accomplished using analog control, which is
extremely fast-acting and reliable. There are 5 different circuits working independently: Radial:
Upper X, Y; Lower X, Y and Axial: Z.
The upper radial Y-axis operation is shown in Figure 7. The principle of operation is the same in
each case.
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Figure 7 - Schematic of the levitation system.
2.4. Power Conversion Module (PCM)
The PCM is a bi-directional system capable of sourcing or sinking power to and from the stator. It
converts variable frequency, variable voltage from the stator and delivers a constant voltage DC
output. Conversely, it converts DC power from the UPS system DC bus to variable frequency,
variable voltage output to the stator as directed by the PCMC to increase the speed of the
synchronous reluctance motor-generator.
2.4.1. Power Conversion Module Controller (PCMC)
The power conversion module controller is located within the power conversion module. The
PCMC uses microprocessor-controlled logic to control the six pulse IGBT solid state switches
and monitor the active magnetic levitation system. These operations are firmware controlled
eliminating the need for manual adjustments. The logic includes self-test and diagnostic
circuitry to identify any faults. Diagnostics are performed via the system’s control panel or via a
PC through the RS232 communication port.
2.4.2. IGBT Power Conversion
The PCMC provides overall control of the VSS+DC as well as specific control of the
synchronous reluctance motor-generator via the IGBT solid-state switches within the PCM.
When delivering DC power, the output of the synchronous reluctance generator is rectified to
DC by passing the high frequency AC current through a solid-state power conversion device.
The DC output voltage of the VSS+DC has less than 2% RMS ripple.
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The voltage and frequency are adjusted using pulse width modulation. The IGBT switches
operate at a frequency of 18 kHz to produce the smooth sinusoidal current waveform to and
from the motor-generator. This is smoothed out further using an inductive and capacitive filter.
2.5. Flywheel Module
The Flywheel Module houses several major components:
Š
The Rotating Group (high-speed carbon composite flywheel, high-speed shaft and rotor
of the Motor-Generator)
Š
The Motor-Generator (synchronous reluctance technology)
Š
The Molecular Vacuum Pump
Š
Flywheel Sensors
Š
Active Magnetic Levitation Hardware
Š
Safety System
Figure 8 - Flywheel module
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2.5.1. Rotor/Flywheel (Rotating Group)
The flywheel cylinder, made of carbon/glass composite, is mounted on a metal shaft with
integral motor-rotor to form the rotating group. The rotating group is magnetically levitated and
centered so that it does not touch any other part while in normal operation.
Figure 9 - Rotating group
2.5.2. Motor-Generator
The rotor is positioned within the stator to provide the motor-generator function of the VSS+DC.
The stator is liquid cooled after significant discharge and operates within a housing in which air
has been evacuated. Together the stator and rotor operate as a synchronous reluctance
motor-generator, producing enough power for the system to supply its own internal demand
and to supply to the output DC bus up to rated power. The illustration in Figure 10 shows the
four poles of the synchronous reluctance rotor.
Figure 10 - Cross-section of the synchronous reluctance motor rotor
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2.5.3. Vacuum System
During manufacture, the vacuum chambers are baked and evacuated to remove water vapor.
The vacuum system is then permanently sealed. The VSS+DC does not require any mechanical
vacuum pump, common to other commercial flywheels. The vacuum system relies on
absorbers to maintain a rough vacuum within the upper chamber. A zero-maintenance
patented molecular vacuum sleeve acts with the flywheel shaft to maintain a high-vacuum in
the lower chamber of much less than 100 microTorr (10-7 atmosphere). The absorber material
only needs to be recharged or changed once every 20 years.
Figure 11 - Vacuum system operation
2.5.4. Flywheel Sensors
2.5.4.1. Speed
The speed detection system uses an infrared emitter and a sensor to detect shaft rotation. A
hole drilled through the shaft allows light to pass and is detected on the opposite side by an
infrared detector. This signal is used to detect rotor angle and speed. The pulsed signal
passes into the 6711 DSP to be converted into a speed signal. This is then passed to the
2812 DSP. The 2812 checks for over-speed and shuts down the power electronics if this
occurs. If either of the processors lock-up, the rotor will slow down to ensure an over-speed
cannot occur.
2.5.4.2. Temperature
The stator and rotor temperature detectors are thermocouples. The stator sensor is a type J
thermocouple potted into the stator windings. The rotor sensor is a non-contact type sensor
that detects rotor surface temperature and gives an output in a type J thermocouple format.
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Figure 12 - Schematic for the speed and temperature sensors
2.5.5. Active Magnetic Levitation Hardware
The electromagnets and capacitive displacement sensors that provide the active magnetic
levitation are located within the flywheel module. A full description of their operation is provided
in section (2.3).
2.5.6. System Safety
Every composite flywheel is inspected, spin balanced and over-speed tested in accordance
with NEMA guidelines. A patented dual-wall containment ensures that in the unlikely event a
flywheel were to separate during operation, the 2-inch thick steel inner housing would retain
the rotating group. In repeated forced destructive tests, the carbon fiber of the flywheel cylinder
expands and transfers torque to the inner housing. The inner housing is then allowed to rotate
inside the outer housing. The cooling fluid in the outer housing, which surrounds the inner
housing, acts as a dynamic brake. The stored energy is released in a controlled manner as the
flywheel / inner housing comes to a rest. The outer housing holds the entire safety system and
acts as a reservoir for the cooling fluid
The VSS+DC has been throroughly tested under the following fault conditions with no adverse
safety effects:
y Motor-generator AC short circuit
y DC short circuit
y PCM failure
y MLC failure
y Rotating group failure
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Outer Housing
Rotating Group
Inner Housing
Coolant
Figure 13 – Cutaway of flywheel module
2.6. Cabinet
The VSS+DC is housed in a compact free-standing cabinet with a NEMA 1 construction rating or IEC
equivalent. No space is required between the back or sides of the cabinet and any walls. A front
clearance of 36” is required per the National Electrical Code. The VSS+DC accommodates top
(standard) and side entry cables. The VSS+DC can be rolled into place and is small enough to fit
through standard door openings.
2.7. Ventilation and Cooling
The VSS+DC stator and power electronics are liquid cooled with a liquid-to-air radiator that operates
following a significant discharge and resultant heating of the motor-generator. The radiator within the
VSS+DC package is designed for natural and forced air-cooling. Air inlets are in the bottom front of the
VSS+DC enclosure, exhaust exits the top of the unit. Air filters are available as an option for dusty
environments. A minimum 12” clearance overhead is required for exhaust airflow.
The VSS+DC was designed with reliability in mind, the radiator is positioned to take advantage of
natural cooling and forced-air and forced-coolant circulation occurs only when there is an elevated
temperature. The coolant circulating pump is a highly reliable magnetically coupled centrifugal
pump powered by a brushless DC motor. This pump operates only when there is an elevated
temperature within the stator or the PCM. The pump is maintenance-free for the life of the flywheel
system due to the infrequent operation of this high-reliability component.
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3. System Configuration
3.1. Modes of Operation
The VSS+DC consists of a variety of operational modes. Each Mode is based on a set of
programmed conditions. The Control Panel indicates the current Mode and the Status of that Mode.
Function keys are enabled or disabled depending on the Mode and Status.
The VSS+DC modes are:
ƒ OFF (3.1.1)
ƒ STARTUP (4.1.2)
ƒ CHARGE (3.1.3)
ƒ READY (3.1.4)
ƒ DISCHARGE (3.1.5)
ƒ SHUTDOWN (3.1.6)
ƒ COAST (3.1.7)
ƒ FAULT (3.1.8)
The VSS+DC is programmed to operate in a variety of conditional modes. The modes and the status
for each sode are indicated on the control panel. The VSS+DC is set up to transition through the
various modes with no or minimal user intervention.
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Figure 14 - Typical Modes of Operation
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3.1.1. OFF Mode
When the VSS+DC is initially powered on, it enters the OFF mode and magnetically levitates its
rotating group. A manual user command will make the system transition from OFF mode to
STARTUP mode if all start-up conditions are met.
NOTE
Start-up conditions are:
1. UPS DC bus voltage ≥ Vcharge; and
2. VSS+ status is “OK”.
The VSS+DC will also enter OFF mode at the end of a shutdown and will transition automatically
from SHUTDOWN mode to OFF mode.
3.1.2. STARTUP Mode
In STARTUP mode, the VSS+DC will charge (increase flywheel rotation speed) up to the
minimum operating speed. At this minimum speed the “State of Charge” = 0%. At that point the
VSS+DC will automatically transition into CHARGE mode.
The VSS+DC will be in STARTUP mode as long as:
1. VSS+DC SOC is less than 0%; and
2. UPS DC bus voltage ≥ Vcharge
NOTE
In STARTUP mode, the VSS+DC cannot support the UPS DC bus.
In case the UPS DC bus voltage drops below Vcharge while in STARTUP mode, the VSS+DC
will transition automatically into COAST mode. As soon as the UPS DC bus voltage rises above
Vcharge, the VSS+DC automatically exits COAST mode and resumes STARTUP mode.
3.1.3. CHARGE Mode
To charge itself, the VSS+DC will draw power from the UPS DC bus to accelerate the flywheel
(as long as the UPS DC bus voltage is over Vcharge). In this mode, the VSS+DC SOC will
progressively increase from 0% to 100%.
The VSS+DC will be in CHARGE mode as long as:
1. VSS+DC SOC is between 0% and 100%; and
2. UPS DC bus voltage ≥ Vcharge.
NOTE
While in CHARGE mode, the VSS+DC can still support the UPS DC bus.
3.1.4. READY Mode
When the SOC reaches 100%, the unit will automatically transition into READY mode. This is
the mode in which the VSS+DC will spend most of its operating time. In this mode, the VSS+DC
maintains its State Of Charge above 99.5%. The VSS+DC SOC will be allowed to drift down to
SOC = 99.5%, at which point it will temporarily transition back into CHARGE mode and charge
back up to READY mode and a SOC = 100%. During normal operation, the VSS+DC will
continue to automatically transition between the READY and CHARGE modes to maintain a
SOC between 99.5 and 100% until either a DISCHARGE or SHUTDOWN is initiated.
The VSS+DC will be in READY Mode as long as:
1. VSS+DC SOC is between 99.5% and 100%; and
2. UPS DC bus voltage > Vcharge.
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3.1.5. DISCHARGE Mode
Starting from either CHARGE or READY mode, the VSS+DC will enter the DISCHARGE mode if
the UPS DC bus voltage goes below Vcharge. In DISCHARGE mode, the VSS+ will regulate
the DC bus at Vreg.
The VSS+DC will be in DISCHARGE mode as long as:
1. UPS DC bus voltage < Vcharge; and
2. VSS+DC SOC is more than 0%.
NOTE
The VSS+DC will transition from DISCHARGE mode to CHARGE mode if the UPS DC
nus recovers (UPS DC Bus Voltage ≥ Vcharge) before the VSS+DC SOC reaches 0%.
In case the UPS DC bus doesn’t recover before the VSS+DC SOC reaches 0%, the
VSS+DC will transition into SHUTDOWN mode.
3.1.6. SHUTDOWN Mode
In SHUTDOWN mode, the flywheel will actively spin down. There are two ways the VSS+ can
transition into SHUTDOWN mode:
1. Following a VSS+DC discharge down to SOC = 0%
This is the most common SHUTDOWN process. This occurs when the VSS+DC SOC drops
below 0% and the UPS system DC bus voltage is less than Vcharge. If the VSS+DC entered
the SHUTDOWN mode after DISCHARGE mode, the VSS+DC will automatically transition
into STARTUP mode when the UPS system DC bus voltage returns to a value greater than
Vcharge (i.e. when utility input returns or the backup generator supplies power to the UPS).
2. User initiated SHUTDOWN
In any mode except OFF, the user may command the VSS+DC to transition to SHUTDOWN.
While in SHUTDOWN mode, the user will still be able to command the VSS+DC to transition
into CHARGE mode (if SOC > 0%) or STARTUP mode (if SOC<0%), provided that the
UPS system DC bus voltage is greater than Vcharge.
3.1.7. COAST Mode
A transition into COAST mode can only occur when the UPS system DC bus voltage droops
below Vcharge (and above 350 Vdc) while the VSS+DC is in STARTUP mode. While in COAST
mode the VSS+DC is in an idling condition. As soon as the UPS DC bus voltage rises above
Vcharge, the VSS+DC will automatically exit COAST mode and resume STARTUP mode. If the
voltage droops below 350 Vdc, the VSS+DC will enter SHUTDOWN mode.
3.1.8. FAULT Mode
The VSS+DC includes self-test and diagnostic circuitry such that most system malfunctions can
be identified. In case of a system malfunction, the VSS+ will transition into the FAULT mode.
While in FAULT mode, the VSS+DC is disabled – i.e. all power electronics are turned off. Most
faults are cleared automatically by the system without a need for user intervention. Some faults
do require user action to clear the fault or to notify your Pentadyne-Certified Service Provider
(Please refer to the Section 6 Troubleshooting for more information).
NOTE
Depending on the nature of the fault, the VSS+DC may still be capable of supporting the
UPS DC bus. Please refer to the Section 6 Troubleshooting for more information.
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3.2. User-configurable System Parameters
In order to support a wide array of UPS integrations, the VSS+DC can be configured using the
following parameters:
3.2.1. Charge Voltage (Vcharge)
Vcharge is the voltage threshold above which the VSS+DC begins to charge/recharge. Vcharge
must be set at least 10 Vdc greater than Vreg.
ƒ
ƒ
Range: 350-600 Vdc
Default setting: 520 Vdc
3.2.2. Regulation Voltage (Vreg)
Vreg is the voltage set-point at which the VSS+DC will regulate the DC bus voltage in discharge
mode. Vreg must be set at least 10 Vdc less than Vcharge.
ƒ
ƒ
Range: 340-590 Vdc
Default setting: 500 Vdc
3.2.3. Regulation Voltage Droop During Discharge (Vreg Delta)
Vreg Delta is the programmed amount of voltage drop from the beginning of discharge (Vreg)
to the end of discharge (SOC = 0%)
ƒ
ƒ
Range: From 0 to [Vreg - 250] Vdc (Ex: if Vreg = 500, then the Vreg Delta can be set
between 0 and 250 Vdc)
Default setting: 0 Vdc
3.2.4. Maximum Charge Current (Max Charge Current)
Max charge current is the maximum current the VSS+DC is allowed to draw from the UPS
DC bus.
ƒ
ƒ
Range: 1-50 A
Default setting: 20 A
3.2.5. Charge Conductance (Charge Amps/Volts)
Charge amps/volts is used to set the VSS+DC charging current drawn from the UPS DC bus
based upon how much the UPS DC bus voltage is above Vcharge and so without exceeding
the max charge current.
ƒ
ƒ
Range: 0.1-10 A/V
Default setting: 2 A/V
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4. Maintenance & Reliability
The VSS+DC is designed for maximum uptime availability and minimal preventive servicing while online.
There are no user serviceable parts in the VSS+DC other than the optional air filter. Please contact a
Pentadyne-Certified Technician before attempting to remove or service any components of the system.
No bearing maintenance or replacement is required over the life of the VSS+DC. No vacuum pump
maintenance or replacement is required over the life of the VSS+DC.
The optional inlet air filter in the cabinet will need to be replaced when dirty enough to reduce air flow
into the cabinet. Ambient conditions at the installation site will determine the frequency of replacement.
The VSS+DC flywheel module is designed for a 20-year service life before any recommended
maintenance interval. At that interval, the vacuum absorbers should be replaced or regenerated.
Replacement of the capacitor pack is recommended at 6-year intervals and is the only downtime
maintenance (one hour).
The reliability of the VSS+DC power electronics is consistent with UPS power electronics of comparable
energy levels. The mechanical assemblies are of higher life and reliability than other commercially
available flywheel systems due to the elimination of rolling element bearings and external vacuumpumping devices.
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