Part 3: Photovoltaic power station energy storage side converter (PCS) system equipment level inspection and operation and maintenance SOP
This article corresponds to the panoramic topology diagram of the energy storage power station [Module 3: Energy Storage Converter PCS System], covering the PCS cabin dustproof ventilation, AC and DC incoming switches, IGBT power modules, DC support capacitors, filter inductors and secondary control and protection logic.
1. PCS converter cabin appearance, dustproof ventilation and AC/DC inlet channels
(1) Cabin environment and protection level inspection
Cabin temperature and humidity control: Check the cabin temperature and humidity sensor. The ambient temperature inside the cabin must be controlled between 0 ℃ ~ 40 ℃; the relative humidity must be < 70% RH. The anti-condensation heater must start automatically when the humidity is ≥ 75% RH.
Hatch sealing: Check the EPDM sealing tape of the container door to see if there is any cracking or falling off, and there is no gap to let light through when closed.
(2) Dust filter cleaning and waterless purging SOP
Disassembly and cleaning of the dust filter: Remove the primary filter cotton from the air inlet, clean it with an industrial vacuum cleaner or rinse it with neutral detergent, and put it back after it is completely dried (moisture content 0%).
SOP for waterless purging in the cabin (annual power outage and overhaul): Apply for power outage for power inspection and connect the ground wire. Use a compressed air pump with a high-efficiency water removal filter (the air pressure is strictly controlled at 0.20 ~ 0.30 MPa), equipped with an insulated nozzle hose, and blow the gaps between the circuit board and the radiator in a "top to bottom" order.
It is strictly prohibited to use a wet cloth with water or an air gun that has not removed water to clean the circuit board.
(3) AC and DC incoming circuit breakers and fast fuses
DC side circuit breaker (DC Breaker): Disassemble the arc extinguishing cover and check that the grid plate has no ablation and deformation; the magnetic blowing coil is well insulated and has no burning smell.
aR-class semiconductor rapid fuse: Check that the red striker does not pop out, and use a microohmmeter to measure the contact resistance at both ends of the fuse, which must be ≤ 0.1 mΩ. If the resistance increases, it means that the internal melt has been partially ablated and must be replaced.
AC side circuit breaker (AC Breaker): Check the energy storage time of the electric energy storage mechanism < 10s; measure the three-phase closing asymmetry must be < 1.0 ms.
Infrared temperature measurement and tightening torque standards:
After running at full power for 30 minutes, use an infrared thermal imaging camera to scan the AC/DC circuit breaker terminals. The operating temperature must be < 65 ℃, and the temperature difference between phases/poles ΔT ≤ 5.0 ℃. If the temperature of the terminal block is > 75 ℃ or the temperature difference ΔT ≥ 15 ℃, the power must be cut off to disassemble the copper bar, polish the oxide layer and apply 0.1 mm anti-oxidation conductive paste, and then tighten the bolts according to the following table:
2. PCS core inverter unit and power module (IGBT) operation and maintenance
(1) IGBT module and thermal grease overcoating SOP
IGBT junction temperature monitoring: the junction temperature at full load operation must be < 85 ℃; when the junction temperature reaches 95 ℃, the power will be automatically derated by 50%; when the junction temperature reaches 105 ℃, an over-temperature trip will be triggered. Check that the driver board triggering fiber is not bent or blocked, and that the driver board indicator light is normal.
Thermal grease recoating SOP (performed every 3 years or when the junction temperature rises > 10°C from the initial level):
Step 1: Cut off the power, check the power, and use a special discharge rod to release the residual charge of the DC bus (make sure the DC bus voltage is < 10V).
Step 2: Remove the IGBT module and completely wipe off the old silicone grease from the base plate with isopropyl alcohol and a lint-free cloth.
Step 3: Use a scraper or screen printing to evenly apply a layer of new thermal conductive silicone grease (thermal conductivity > 3.0 W/m·K, thickness controlled at 50 ~ 100 μm).
Step 4: Reinstall the module, tighten the bolts twice in a diagonal cross sequence (torque: 3.0 ~ 5.0 N·m), and rewire and receive power.
(2) DC bus support capacitor (DC-Link) maintenance
Appearance inspection: There are no bulges in the capacitor shell, no leakage, and no explosion-proof valve rupture.
Capacity and ESR test: After full discharge after a power outage, use an LCR meter to measure the capacitance capacity. When the capacity attenuates > 10% from the nominal value or the equivalent series resistance (ESR) increases > 50% from the initial value, the entire capacitor must be replaced.
Bus voltage ripple coefficient: Under full power discharge, the actual measured DC bus voltage ripple coefficient using an oscilloscope (AC coupling mode) must be < 1.0%.
(3) Maintenance of filter inductor and LC filter
Insulation and temperature rise: Use a 1000V megger to measure the insulation resistance of the inductor winding to ground must be ≥ 100 MΩ; the operating temperature must be < 90 ℃.
Noise check: Under full load charging and discharging, the measured noise at a distance of 1 meter from the cabinet must be < 75 dB. If there are abnormal high-frequency magnetic shock noises, the iron core bolts must be retightened (M12 torque: 70 N·m).
3. Secondary control loop, sampling board, phase locking and grid adaptive protection logic
(1) Sampling accuracy and zero point calibration
Sampling accuracy: Use a power quality analyzer to measure the actual voltage/current and compare it with the monitoring screen. The voltage sampling error must be ≤ ± 0.5%, and the current sampling error must be ≤ ± 0.5%.
Zero point calibration: If the monitor displays a small current in the standby state (current 0 A), "zero offset automatic calibration" must be performed in the control background.
(2) Measured SOP of phase-locked loop (PLL) and anti-islanding (Anti-Islanding)
Phase-locked loop tracking: When the grid-side frequency fluctuates between 45.0 ~ 55.0 Hz, the phase-locked loop must accurately lock the phase within < 20 ms, with a tracking error of < 1°.
Measured SOP for anti-islanding protection: When the large power grid loses power, the PCS must automatically disconnect the grid-connected switch and stop inversion within ≤ 2.0s.
Actual measurement steps: In the grid-connected discharge (50% power) state, manually open the grid-side analog circuit breaker. Oscilloscope monitoring shows that the PCS must cut off the AC current output and report a grid-side power loss alarm within < 200 ms.
(3) Low/high voltage ride through (LVRT/HVRT) and wind turbine maintenance
Voltage ride-through: When the grid-side voltage drops to 20% of the rated voltage, the PCS must ensure that it does not go off-grid within 0.625s and inject dynamic reactive current; when the voltage rises to 130%, it must ensure that it does not go off-grid for 0.50s.
Fan array: Check the air pressure switch function. When a fan fails and stops spinning, the PCS must report a fan failure within <3 seconds and derate the power by 30%. Fans must be replaced in groups after 20,000 operating hours.
Photovoltaic power station energy storage side PCS converter container cabin/converter cabinet area on-site inspection sign-in form
Power station name: _______________________________ Inspection date: ____ month ____ day, 2026
Inspection area: PCS converter container cabin/converter cabinet area Inspection person in charge: ____________________
1. On-site equipment inspection and testing actual data records:
2. Inspection defect registration and defect elimination dispatch:
3. Inspection sign-in and review signature:
Inspection engineer (signature): _______________ Supervision engineer (signature): _______________
Review (signature) of the shift leader: _______________ Sign-in and filing time: ____ hour on ____ month ____ day 2026