GHM GROUP CORPORATE | GHM Messtechnik GmbH Schloßstr. 6 | 88453 Erolzheim | GERMANY Phone +49 7354 937233-76 | Fax +49 7354 937233-88 www.ghm-group.de | [email protected]Product information IPV 1 pi-ipv_system_e V1.40-00 Monitoring and Controlling Energy Efficiency of Photovoltaic Installations Features System Current and voltage supervision of solar panels Control of switching states Sources Shunt and inductive sensors in string arrays Standard signals from temperature, wind speed, and irradiation sensors Door switches Digital outputs of power inverters Applications ● Solar Power Plants ● Off-Grid Systems ● Roof Systems
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Product Information IPV Monitoring and Controlling Energy … · Transmitter GTMU Optimum ...
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Functions and BenefitsInstallations generating green energy have to beoperated economically and efficiently to feed in amaximum of energy. For that consistent informationabout their efficiency is absolutely mandatory.Permanent control also provides early detection ofdefects and malfunction of a PV system or its solarpanels. Further on additional access control andequipment condition monitoring should be set up.
Data and state acquisition of the PV system isdesigned with modular components. There aremodules measuring DC current and voltage of theindividual strings, modules for panel temperature, andsignals of wind speed and irradiation sensors.
Digital-In modules monitor e.g. switching states ofdoor switches and inverters.
The individual DIN-rail modules are mounted in open-field array boxes or in a local indoor control cabinet asneeded by application and quantity. There they arelinked each time via an internal bus with an intelligentcommunication unit transmitting the collected dataover a field bus (Modbus RS485 or CAN) to the nexthigher control level.
The modular design allows manifold combinationsand upgradings.
So the modules are not just suited for large powerplants, but also for monitoring of medium and smallpower installations.
The current-to-voltage characteristic of a solar panelbuilt of several solar cells connected in series, reflectsthe specific properties of this power generator. Thecurve of a solar panel is very similar to a single cell,despite the different scale factor. Solar panels areagain connected in series or in parallel to generatemore current or voltage as appropriate.
Under normal conditions the characteristic curve islike:
Fig.1 Schematic view of IV characteristic
Voltage value at MPP is approximately 80% opencircuit voltage of a solar panel.
MPP (Maximum Power Point) is the operating pointwith maximum power as product of cell current andvoltage:
Fig. 2 Schematic view of maximum powercharacteristic
From the characteristics it can be learned howimportant it is, that the operating voltage of the panelsis not suppressed too much below the MPP, avoidingpotential energy losses. Degradation of cells byinternal or external influences over time can be seeninstantly from the measured curves. Depending onhow many panels are combined to a string, occurringmalfunctions can also be localized physically precise.
The energy efficiency of the strings is also remarkablydependent on a mismatch caused by e.g. shadowingof cells or different input resistances.
Fig.3 Schematic view of shadowing impact within a10..75 % range (solid line ideal characteristic)
The output current of a solar panel is proportional toincident solar radiation. Maximum radiated power onearth is in the range of 800 to 1200 W/m².
Fig. 4 Schematic view of irradiation impact within 100to 1000 W/m² (solid line
The energy yield of a panel is determined by its cellwith the lowest yield. Degradation of cells by internalor external influences over time, can be seen instantlyfrom the measured curves. Depending on how manypanels are combined to a string, yield losses can alsobe localized physically precise.
The energy yield of solar panels is also affected bycell temperature, as cell voltage is decreasing withincreasing temperature. For reference, temperature inan array is measured exemplarily at a characteristicspot.
Fig. 5 Schematic view of temperature impact within(from left) +80..25 °C (solid line)
Temperature measurement can be done with atemperature transmitter with signal current or voltageoutput . Pt100 sensors can be used directly withoptional adaptation of the AD module.
Data from wind speed and irradiation sensors viasignal current or voltage transmitters can also beacquired and incorporated in the monitoring of theinstallation.
Switching states of e.g. doors can be supervised withthe digital input module. This accommodates safetyaspects (security control) or shutdown of inverters.
The following listed measurement devices guaranteeefficient monitoring of PV systems' energy yield.Further on malfunction of or in strings depending onthe layout of the monitoring system can be recognizedquickly, avoiding potential energy and financial losseswith it.
Device Overview
Module Input Output
Pa
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Se
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Vo
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e
Cu
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nt
Sig
na
l
Vo
ltag
e
Sig
na
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Cu
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Pt1
00
Dig
ita
l-O
ut
Inte
rna
l (S
PI)
Mod
bu
s
RS
48
5
CA
N
IPV Voltage 5
IPV Current 5
IPV Signals AD 6
IPV Signals D 6
IPV Communication 7
Standard, Optional, per type of sensor
Mistakes reserved, technical specifications subject to change without notice
This IPV module serves to transmit data acquired by the current,voltage, and signal modules of solar systems for string efficiencymonitoring in medium sized or large facilities.
Data of the individual measurement modules are picked up overthe internal serial bus and processed. Up to 18 subscribers can beoperated via the internal bus, and configured for ID andmeasurement ranges accordingly. The digitized measurement dataare then transmitted via a field bus (Modbus RS485 or CAN) to thenext superordinate level (like a local control unit or to a data loggerfor smaller facilities).
Technical Data
Supply voltage 24 V DC ± 10 %
Power consumption at nominal voltage 10 W for 8 subscribers
Electrical isolation 1000 V DC
Environmental temperature -25..+60 °C
Module Communicationinternalexternal
serialField bus
(Modbus RS485, CAN bus)
Installation
Power supply and external bus via screw terminal2,5 mm²
Measuring quantities and supply of the modulesvia internal bus with T-Bus connection of housing
„Industrial Electronics“Displays / ControllerTransmitter / Signal conditioningIsolating convertersSafety and Monitoring DevicesPower ElectronicsCalibration and Testing
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