Site Acceptance Testing (SAT) demonstrates the successful operation of the SCADA system in the field, including software and hardware checks, HMI and alarm functionality, and controls.
In our previous article, we discussed SCADA Factory Acceptance Testing (FAT), which takes place before the SCADA rack ships to the solar PV project site. The SAT occurs after the SCADA system has been installed onsite, all devices are connected and communicating, and the SCADA integrator has been able to test and tune the controls. This may be during or after site commissioning.
The best way to prepare for a SAT is to understand its purpose, expected outcomes, and process.
1. What purpose does conducting a SAT serve after shipping a SCADA system to the field? What is the expected end goal or outcome?
The SAT serves as the final testing for a SCADA system, demonstrating all functionality and providing an opportunity to note and address any punch list items prior to finalizing the project and providing closeout documentation. It is the culmination of the whole project from the SCADA perspective.
The SAT is done once the SCADA system is installed in the field to demonstrate that:
- All connections and functionality verified in the FAT have been maintained
- All new connections and functionality that couldn't be tested prior to onsite installation meet customer expectations
Controls testing can be simulated during the FAT but can only truly be performed under actual site conditions once the SCADA system has been installed onsite and is connected to the field and substation devices. This ensures that customer expectations and utility/ISO requirements are met.
The end goal of the SAT is that either the customer approves all of the functionality, or any deviations from expectations are noted in the punch list to be addressed.
2. Why is it necessary to have the SAT be customer witnessed (either in person or virtually)?
It's necessary to have the SAT be customer witnessed and verified to ensure that all controls operate as expected, are represented properly on the HMI, and verified through accurate feedback from the site. The SAT is designed to make sure everyone agrees that the functionality is approved.
3. What things are tested during a SCADA system SAT? How does prior PPC, HIL modeling with a RTDS of the site help with conducting the SAT?
The standard SCADA system SAT verifies:
- Software installation and licensing
- Hardware appearance/locations/installation/functionality/etc.
- Backup power supply
- Communication to all internal and external devices
- HMI functionality verifications
- Alarm testing
- Controls testing for trackers (auto and manual mode, stow, clean, manual setpoints)
- Controls testing for inverters (individual start and stop, individual real and reactive power setpoints)
- Overall site controls testing:
- Real and reactive power (PF, AVR, Q) control loops
- Open/close breakers
- Capacitor banks (open/close, auto mode)
- Documentation check
Prior PPC, HIL modeling using RTDS real-time simulator software can make this testing process easier. By simulating the exact devices that will be out in the field, it allows the SCADA integrator to test the controls more accurately and thoroughly prior to shipping the SCADA rack to the field. It is much faster and easier for the SCADA integrator to make adjustments to the controls while the rack is still in-house, and there are less likely to be lengthy adjustments and delays before finalizing the project.
4. How do EPCs facilitate SATs? What is their role in the process?
EPCs facilitate SATs by:
- Coordinating commissioning of the site that must occur prior to final testing
- Ex: Trackers and inverters must be commissioned prior to controls testing, to ensure the SCADA integrator can send setpoints, issue start/stops, and troubleshoot any issues
- Addressing any issues that come up during commissioning and bringing relevant parties together to troubleshoot
- Approving the SAT functionality
- Generating punch list items (if any)
EPCs are also responsible for coordinating overall site testing with the utility and ISO, to ensure that approval is gained prior to adjusting real and reactive power setpoints that would affect the grid. The AVR testing usually involves voltage setpoint changes, so it has to be approved and scheduled in advance.
5. Do asset owners have a role in SATs?
Asset owners are welcome to witness the SAT, giving them an opportunity to ensure SCADA system functionality meets their expectations.
Nor-Cal Controls sets customers up for success with solar PV SCADA systems.
With over 14GW worth of successfully commissioned solar PV projects to date, Nor-Cal Controls provides SCADA systems that meet customer and ISO/utility requirements and deliver cost efficiency over the long term. Since our SCADA systems are based on open architecture hardware and software, our customers avoid proprietary data access fees and restrictive service contracts.
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