What are the common faults and handling methods of 30kw grid-connection boxes?
Inverter: This is one of the most critical components in the grid-connection box. It is responsible for inverting the direct current generated by photovoltaic modules into alternating current, making it meet the requirements of the power grid in terms of voltage, frequency, etc.
Circuit Breaker: Including DC circuit breakers and AC circuit breakers, which are used to cut off the circuits on the DC side and AC side respectively. When the system has faults such as overload and short circuit, it can quickly disconnect the circuit to protect equipment and personnel safety.
Lightning protector: Used to prevent damage to the grid-connection box and other equipment of the photovoltaic system caused by lightning overvoltage, improving the lightning protection capability of the system.
Metering device: Used to measure the electric energy transmitted by the photovoltaic system to the power grid, facilitating users to know the power generation and the power grid company to settle electricity charges.
Monitoring and control module: It can monitor the operating parameters such as voltage, current, and power of the photovoltaic system in real time. Some grid-connection boxes also have remote communication functions, allowing users to view the system operation status remotely through mobile phone APPs or computers.
Residential distributed photovoltaics: For some families with large electricity consumption, such as villas or rural self-built houses, when installing a photovoltaic system of about 30kw, the 30kw grid-connection box can well meet their grid-connection needs, realizing self-use of generated electricity and surplus electricity being connected to the grid.
Small industrial and commercial places: Small factories, supermarkets, office buildings and other industrial and commercial places have certain space on the roof or idle sites to install photovoltaic modules. A 30kw photovoltaic system can provide part of the electricity for them, reducing electricity costs, and the 30kw grid-connection box is an important device to realize the grid connection of photovoltaic power.
Agricultural photovoltaic projects: Small photovoltaic power stations built on agricultural facilities such as agricultural greenhouses and fish ponds usually have a capacity of about 30kw. The 30kw grid-connection box can ensure the stable connection between these photovoltaic power stations and the power grid, realizing the complementarity between photovoltaic power generation and agricultural production.
Site selection: Choose a place with high terrain, good ventilation, and far from flammable and explosive materials. Avoid installing in low-lying waterlogged areas or environments with strong vibration and corrosive gases. At the same time, ensure that there is enough space around the grid-connection box to facilitate later maintenance and overhaul.
Fixing the box body: Firmly fix the grid-connection box on the preset foundation or bracket to ensure that the box body is vertical and stable, preventing the box body from tilting or shifting due to vibration or wind force.
Electrical connection: Wire according to the electrical schematic diagram, first connect the line from the photovoltaic module to the DC side of the grid-connection box, then connect the line from the AC side of the grid-connection box to the power grid. When wiring, ensure that all connection points are firm and reliable, avoiding looseness and poor contact. At the same time, pay attention to distinguishing positive and negative poles, phase lines, and neutral lines to prevent wrong connection.
Grounding: The grid-connection box must be reliably grounded, and the grounding resistance should meet the requirements of relevant standards (generally not greater than 4Ω). Grounding can effectively prevent electric shock to personnel due to equipment leakage and lightning overvoltage, ensuring the safe operation of the system.
Inspection and testing: After installation, conduct a comprehensive inspection of the wiring of the grid-connection box to ensure there is no wrong connection or missing connection. Then conduct a power-on test to check whether the inverter works normally, whether various operating parameters are within the normal range, and whether protection devices such as circuit breakers and lightning protectors are sensitive and reliable.
Regular cleaning: Regularly clean the dust and debris on the surface and inside of the grid-connection box to keep the box well-ventilated. When cleaning, first cut off the power supply, use a dry cloth or brush for cleaning, and avoid wiping with water or a damp cloth to prevent short-circuit faults.
Checking components: Regularly check the circuit breakers, lightning protectors, terminal blocks and other components inside the grid-connection box to see if there are phenomena such as looseness, overheating, and oxidation. If loose terminal blocks are found, tighten them in time; for components with overheating marks or damage, replace them in time.
Monitoring operating parameters: Through the monitoring and control module of the grid-connection box, regularly check the operating parameters such as voltage, current, and power of the system, compare with historical data, and timely find abnormal system operation. If abnormal parameters are found, find the cause and deal with it in time.
Lightning protection inspection: Before the thunderstorm season, check the lightning protector of the grid-connection box to see if it works normally. If it is damaged, replace it in time to ensure that the system can get effective lightning protection in thunderstorm weather.
Keeping the box intact: Check whether the box body is damaged, deformed, rusted, etc. Repair the damaged parts of the box body in time, and derust and anti-corrosion treatment for severely rusted ones to ensure the protective performance of the box body.
Inverter not working: It may be caused by too low or too high DC input voltage, internal failure of the inverter, abnormal AC side power grid, etc. First, check whether the photovoltaic modules generate electricity normally, and measure whether the DC input voltage is within the working range of the inverter; then check whether the AC side grid voltage is normal; if the above are normal, it may be an internal failure of the inverter, and at this time, contact professional maintenance personnel for repair or replacement.
Circuit breaker tripping: When the system has overload, short circuit, or leakage, the circuit breaker will trip automatically. When handling, first disconnect all loads, check whether the line has short circuit or leakage, and close the circuit breaker after troubleshooting. If it trips again after closing, further check the lines and equipment to find and eliminate the fault point.
Abnormal reduction in power generation: It may be caused by the decrease in inverter efficiency, too much dust on photovoltaic modules, failure of the metering device in the grid-connection box, etc. First, clean the photovoltaic modules to remove dust and debris on the surface; then check the operating parameters of the inverter to see if they are normal; if the power generation is still abnormal, check whether the metering device is accurate, and calibrate or replace it if necessary.
Damage to the lightning protector: After a thunderstorm, if the grid-connection box is found to be unable to work normally, the lightning protector may be damaged by lightning. At this time, replace it with a new one and check whether other equipment is affected.