Before starting a 200 MW solar plant, a comprehensive electrical checklist and pre-commissioning tests must be performed on all components to ensure safety, functionality, and compliance with standards.
General Pre-Startup Checks
Documentation: Verify all design documents, "as-built" drawings, datasheets, and test certificates are complete and approved.
Safety & PPE: Ensure all personnel have the correct safety gear and understand the lock-out/tag-out (LOTO) procedures.
Visual Inspection: Conduct a site-wide visual inspection for any physical damage, loose connections, or foreign objects (e.g., bird nests).
Labeling and Signage: Confirm all equipment, disconnect switches, cables, and panels are clearly and permanently labeled with relevant warnings and electrical ratings.
Earthing/Grounding: Verify continuity and resistance of the entire grounding system (PV array frames, structures, inverters, transformers, panels) to ensure it meets relevant standards (e.g., less than 2 ohms for a large system).
Component-Specific Checklists
Modules and Array
Mounting Structure: Ensure all modules are securely mounted, and all fasteners are properly torqued.
Wiring & Polarity: Check all string wiring for correct polarity (a reversed polarity string can cause severe damage).
Voltage & Current: Measure the open-circuit voltage (
) and short-circuit current (
) of each string/array to confirm they are within manufacturer's specifications and match expected values under current sunlight conditions.
Insulation Resistance: Perform insulation resistance (Megger) tests on all DC cables to ensure no ground faults or punctures.
Cables and Cabling
Cable Integrity: Visually inspect all AC and DC cables for physical damage, proper routing (DC and AC cables segregated), and protection from physical damage or UV exposure.
Termination: Verify all cable terminations at junction boxes, inverters, and panels use properly crimped lugs/ferrules and are tightened to the correct torque settings.
Glanding: Ensure proper cable glands are installed and tightened to provide sealing and strain relief.
String Inverters
Installation: Verify the inverter(s) is installed in a well-ventilated area with adequate clearance.
Connections: Confirm secure AC and DC connections as per manufacturer instructions.
Settings: Ensure all grid parameters (voltage, frequency limits, anti-islanding protection) are set according to local utility requirements.
Functional Test: Once energized, verify the inverter starts up, synchronizes with the grid, and produces the expected power output.
Transformers, HT Panel, LV800, and ACB
Visual & Mechanical: Inspect for any oil leakages (for oil-filled transformers), proper oil levels, and physical damage.
Pre-Commissioning Tests:
Insulation Resistance (IR) & Winding Resistance: Perform IR tests on transformer windings and all associated panels/breakers.
Ratio & Polarity: Verify transformer turns ratio and CT/PT polarity are correct.
Protection Relays: Test all protective relays (overcurrent, earth fault, etc.) in the ACB and HT panels for correct settings and functionality.
Breaker Operation: Test the mechanical and electrical operation (ON/OFF/Trip) of the Air Circuit Breaker (ACB) and all breakers in the HT and LV panels.
Battery and SACU (Site Auxiliary Control Unit)
Battery Condition: Check individual cell/battery voltages and specific gravity (if applicable).
Connections: Ensure all battery connections are tight and coated with anti-corrosive gel; verify correct polarity.
Ventilation: Confirm the battery location has adequate ventilation and relevant safety equipment nearby (eyewash station, etc.).
Charge Controller: Verify charge controller settings are correct and functional, including low voltage disconnect (LVD) and high voltage disconnect (HVD).
SACU Functionality: Test the Site Auxiliary Control Unit (SACU) and its integration with the battery system to ensure seamless control and power transfer to essential loads.
SCADA and Monitoring
Communication: Verify all field devices (inverters, meters, sensors, switchgear) are communicating with the SCADA server via fiber optic or Ethernet networks.
Data Accuracy: Check that all data parameters (voltage, current, power, energy, irradiance, temperature, alarms) displayed on the monitoring system are accurate and reflect real-time conditions.
Alarm Testing: Simulate alarms and faults to ensure the SCADA system correctly logs and notifies operators.
Remote Control: Test remote control functions (e.g., inverter start/stop, breaker operations) if designed for remote operation.
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