Supervisory control and data acquisition or SCADA is a computer system for gathering and analyzing real time data. It usually refers to centralized systems which monitor and control industrial plants, or complexes of systems spread out over large areas.
Following are the features of a typical SCADA system:
A SCADA collects data such as solar irradiation and ambient temperature from various environmental sensors. These sensors communicate with PLCs or PCs via communication interfaces like RS485 or TCP. The acquired data is then compiled and formatted in such a way that a workstation operator using the HMI can make supervisory decisions to adjust or override normal controls. Data may also be fed to databases and backup servers, often built on a commodity database management system or remote cloud server allowing for trending and other analytical auditing.
Human-Machine Interface or HMI
After collection of data, the information is displayed in such a manner both graphically and numerically such that the monitoring is easy to interpret. This is done using a HMI platform.
In order to prevent the yield losses, system administrators need to be able to remotely check the yielding information like the inverter status, panel status, environment condition etc. The SCADA system includes these data using web functions on it. In case of any faults, checking can be done remotely to solve the issues thus handling the fault on time.
Event and Alarm Management
In case of any system malfunctioning or upcoming maintenance schedules, the SCADA system sends a message and warns the operators.
SCADA also stores all the data from plant production and maintenance in the form of reports, data loggers etc. These data are saved in the local substations including a backup in the main server.
All the information acquired is exported to an SQL Server database for centralizing and analyzing the production of the power plants. Users or system administrators can later view the data for analyzing the performance of that particular plant. The database can be setup remotely using cloud server or local database servers.
Flexibility for Future Expansion
Most of the SCADA systems are designed for additional future inputs like sensors, solar panels, meters etc.
SCADA Solutions in Solar Power Plants
In terms of efficiency, a solar power plant might bring in some hurdles. Thus condition monitoring is very essential for keeping a record of the yield in real time. SCADA systems are designed in such a way that it keeps a track of certain factors such as wind velocity, ambient temperature, performance ratio to name a few.
Unlike Wind SCADA or Gas SCADA, in solar SCADA certain standards in terms of equipment or power plant design needs to be considered. Most of the technologies used for solar are rapidly developing and solar power companies are rushing to keep up. Moreover solar power plants require large areas in unfriendly terrain that is often located in remote or rural areas. Environments may be harsh, with physical exposure posing a continuous risk of damaging the equipments.
Need for SCADA systems
For real time data monitoring, mobile or remote SCADA plays a very important role. Operations and maintenance (O&M) might not always operate at the location of a solar plant site due to lack of resources or equipments. Thus remote monitoring with mobile SCADA proves to be the most efficient means of metering the energy output using remote data acquisition. This can incorporate licensed or license-free radio modems, cell phone, or even satellite connections. Moreover when solar modules fail to function, it becomes necessary for the solar SCADA system to diagnose and troubleshoot solutions for failing hardware. The SCADA system may also need to control functions such as turning cells online or offline as the position of the sun changes, or controlling the angle of the plates.
Commercial scale Solar SCADA
In general, a commercial solar plant sizes from 10kW to 5MW. There is need for a SCADA system in this type of plants too so that the plant works in good condition. Due to the lesser inputs as compared to utility scale plants, the SCADA system is much cheaper. Sometimes these commercial plants set up in academic institutions can not only be used for power output but also for education and demonstration purposes.