1、 Use equipment for testing
Testing equipment: High voltage insulation resistance analyzers or high-voltage insulation bridges are used to test the insulation impedance of equipment (such as inverters, transformers, combiner boxes, etc.) in photovoltaic power plants.
Self diagnosis: For photovoltaic power plants equipped with self diagnostic functions, historical data and electrical parameters can be used to analyze and determine whether there is insulation impedance abnormality.
2、 Check the insulation condition of the equipment
Appearance inspection: Inspect the surface of the equipment to see if there are any issues such as insulation layer damage, aging, or contamination.
Internal inspection: For critical equipment such as inverters, transformers, etc., internal inspection is required to determine whether there are insulation defects or faults.
3、 Trial operation testing
After necessary maintenance or replacement of the equipment, conduct a trial run test to determine if there are any insulation impedance issues during operation.
4、 Adjust settings and parameters
Comparison data: In the online state of the monitoring platform, starting from the time of fault triggering, compare the insulation impedance value of historical data with the insulation impedance protection value data value in the batch instructions entering the control equipment.
Adjust parameters: Based on the comparison results, adjust the "insulation impedance protection point" parameters to ensure the normal operation of the equipment.
5、 Targeted investigation and resolution
Disconnecting and testing: Disconnect the DC switch of the inverter on site, unplug the positive and negative poles of the PV, and use a resistance shaker or multimeter to test the insulation resistance of PV+to ground and PV - to ground. If the insulation resistance is less than the specified value (such as 2 megohms), it is determined to be caused by a PV side problem.
Environmental inspection: If fault alarms occur frequently on rainy days or in environments with prolonged humidity, the surface of the photovoltaic panel can be checked for cracks or water accumulation.
Interface resistance test: Disconnect the inverter DC switch and unplug all PV positive and negative poles, then close the inverter DC switch again (not working), and use the multimeter resistance range to test the resistance between the PV positive and negative input interfaces. If the resistance value is abnormal (such as less than 10K Ω), it is necessary to contact the inverter manufacturer for handling.
6、 Preventive measures
Equipment selection and installation: Choose equipment produced by reputable manufacturers and install it strictly according to the manufacturer's requirements. When installing equipment, insulation strength should be fully considered.
Equipment maintenance: Regularly maintain the equipment to ensure that its electrical parameters are within the normal range.
Plan inspection: Develop an inspection plan and regularly check the insulation impedance of the equipment.
Environmental management: Keep the on-site environment clean and tidy, and avoid situations such as water accumulation and humidity that may cause insulation impedance abnormalities.
By using the above methods, it is possible to effectively identify and solve insulation impedance anomalies in photovoltaic power plants, ensuring their safe and stable operation.