Describe the process of commissioning a new substation, including key tests and inspections performed before energization.

Commissioning a new substation is a critical process that ensures the substation is safe, reliable, and performs as designed before it is energized. The process involves a series of inspections, tests, and adjustments to verify that all equipment is properly installed, connected, and functioning correctly. Visual inspection is the first step. A thorough visual inspection is conducted to check for any signs of damage, missing components, or incorrect installation. Grounding system testing verifies the integrity of the grounding system. Ground resistance measurements are taken to ensure that the grounding system provides a low-impedance path to ground. Insulation resistance testing (Megger) measures the insulation resistance of all equipment to ground. Low insulation resistance indicates insulation damage or contamination. Turns ratio tests are performed on transformers to verify that the turns ratio is correct. Polarity tests are conducted on current transformers (CTs) and voltage transformers (VTs) to ensure that they are properly connected. Wiring checks verify the correctness of all wiring connections, including control circuits, protection circuits, and communication circuits. Functional testing verifies the operation of all control and protection systems. This includes testing circuit breaker operation, relay settings, and alarm functions. Protection relay testing tests the operation of all protective relays to ensure that they respond correctly to faults. This includes testing overcurrent relays, differential relays, and distance relays. Communication system testing verifies the communication between the substation and the control center. This includes testing SCADA (Supervisory Control and Data Acquisition) systems and other communication links. Voltage and current injection tests simulate fault conditions to verify the operation of the protection system and control systems. Transformer testing includes performing a variety of tests on transformers, such as insulation resistance tests, turns ratio tests, and excitation current tests. Oil testing is performed on oil-filled transformers to check the condition of the oil. The results of all tests and inspections are documented. Any discrepancies or problems are corrected before energization. After all tests are completed and verified, the substation is energized. The energization process is carefully controlled and monitored. The substation is gradually loaded to verify its performance under normal operating conditions. Therefore, a thorough commissioning process is essential for ensuring the safe and reliable operation of a new substation.