What are the critical parameters to monitor in a SCADA system for a solar power plant, and how can these parameters be used to identify and diagnose equipment failures?

A SCADA (Supervisory Control and Data Acquisition) system is used to monitor and control a solar power plant. Critical parameters to monitor include: DC voltage and current from each string or combiner box, AC voltage and current from inverters, inverter power output (both active and reactive), inverter status (e.g., operating, fault, idle), grid voltage and frequency at the point of interconnection, weather data (irradiance, temperature, wind speed), and ambient and module temperature. Additionally, energy production (kWh) and performance ratio (PR) should be monitored. These parameters are used to identify and diagnose equipment failures by comparing real-time data to expected values and historical trends. For example, a sudden drop in DC current from a string could indicate a module failure, a string disconnection, or shading. A decrease in inverter power output coupled with a high inverter temperature might suggest an inverter overheating issue. A grid overvoltage or undervoltage condition can trigger protective actions. Irradiance and temperature measurements are crucial for calculating the expected power output and identifying performance deviations. Consistent deviations from expected values can indicate degradation, soiling, or other problems. Alarms and alerts can be set up in the SCADA system to automatically notify operators of abnormal conditions, allowing them to investigate and take corrective actions promptly. SCADA data can also be analyzed to perform predictive maintenance, anticipating potential equipment failures before they occur.