Example of a Solar Photovoltaic (PV) Grid Connected Monitoring System
The system is designed to monitor solar photovoltaic system, using modern,
cost effective approach and software designed in LabVIEW graphical programming language.
A typical, grid tied PV system comprises of:
- Multiple PV panels
- Inverters
- PV panels temperature sensors
- Weather sensors
Sensors are an active type (DC powered), 4-20mA transmitters, AC and DC data is obtained from inverters or dedicated energy meters. The system will collect data from the following devices:
- Weather sensors:
- Ambient Temperature
- Relative Humidity
- Pyranometer
- Anemometer - wind speed and direction sensors
All environmental sensors (4-20mA) are connected to a Data Collector Unit that presents its' output as
Modbus interface to the Real-Time Data Concentrator with RS485 link.
- PV Temperature Sensors
All temperature sensors are of an active type, equipped with 4-20mA transmitters.
- Inverters - DC and AC parameters
All signals are monitored by the system and DC/AC parameters obtained from the Inverters.
Data is retrieved by using plain ASCII or Modbus RTU protocol over RS485 connection,
or any other protocols that is provided with the supplied equipment.
Data Concentrator unit is the National Instruments PXI controller or National Instruments Compact FieldPoint Programmable Automation Controller,
with RS485 ports and Ethernet port. Inverters are connected via RS485 link to the Data Concentrator, which periodically reads data from all the
connected devices and stores them in a large capacity flash memory. Data Storage PC receives real-time data from the Data Concentrator unit and periodically
downloads all the collected data from the Data Concentrator. Data Storage PC stores data records in a local database and generates daily reports in MS Excel
compatible format (TAB delimited text). Data Storage PC allows any PC on the network to connect via the Internet Explorer to view real-time data on demand.
The layout of the system is shown above.
Supported Input Signal Types:
Our monitoring system can be interfaced to a multitude of sensors and instruments. It accepts most commonly used input signal types:
- Voltage ( DC voltage from environmental and DC sensors)
- Current (0-20mA. 4-20 mA from current transmitters)
- Pulse (from energy meters, environmental sensors)
Any kind of electrical output signal from a sensor can be converted to a 4-20mA
current signal (with current transmitters) that has become industry standard due to
the long achievable range of hundreds of meters and very good noise immunity.
Supported Industrial Transmission Protocols
The system supports data transfer over the following industrial protocols:
- Modbus RTU/TCP
- CAN bus
- TCP/IP
- UDP
- ASCII serial communication protocols
- Datasocket
- Backnet-IP
- Profibus
WPG System, Open Architecture Monitoring Systems. August 2009 2
Conversion between protocols can be performed with small, embedded controllers.
Supported electrical communication standards:
- Ethernet
- RS232/RS485
- 1-wire (Dallas Semiconductor)
This allows the monitoring system to communicate and retrieve data from most of
the measuring instruments used in industry and science. These include:
- Laboratory Instruments
- Energy/Power Meters
- Inverters
- Specialized measuring devices
- PLCs, including legacy models; most brands are supported
- Networked, intelligent sensors
- Microcontrollers
Remote Access Methods:
- Cable Networks
The system can be applied to an area that has Ethernet cable network in place.
Extension in Ethernet network range can be made to reach tens of
kilometers by means of fiber optic links.
All transmission protocols listed above are supported over Ethernet networks
- Wireless Ethernet (WiFi)
- Wireless Internet
Through GPRS Modems using service provided by telecommunication company.
- Radio Frequency Transceivers
The system can support large area and form
a mesh radio network with multiple repeaters. Applicable to remote areas not
covered by GPRS service. (wireless Internet access)
- Satellite Phone in areas not covered by wireless Internet service.
Monitoring Systems Examples:
Customize Solutions
We customize all designs to suit the requirements for a specific scenario.
The software can present a SCADA type user interface, designed according to the customer requirements.
SMS messaging upon alarms can be implemented. Environmental sensors can be connected directly to the Data Collector unit or to a
device like SMA Sunny Sensor Box.
The main software features are common for all designs and provide the following:
- Continuous, uninterrupted data collection and storage
- Real-Time display of the parameters
- Long time data storage
- Data stored as binary files and/or in database
- Real-Time data publishing over Ethernet connection
- Historical data display
- Daily calculation of derived parameters
- Daily reports generation in MS Excel compatible format
- Data publishing to third party systems with OPC server or Modbus interface
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