Inverter, also known as power regulator, according to the use of inverter in solar power generation system can be divided into independent power use and grid-connected use of two kinds. According to the waveform modulation can be divided into square wave inverter, step wave inverter, sine wave inverter and combined three-phase inverter. For inverters used in grid-connected systems, they can be categorized into transformer-type inverters and transformerless inverters according to the presence or absence of a transformer.
Solar Inverter Structure
As a direct AC conversion power adjustment device, the inverter is divided into two major parts, the boost circuit and the inverter bridge circuit, which are mainly composed of semiconductor devices. The main semiconductor devices are as follows:
(1) current sensor: requires its high, fast response, low temperature resistance, high temperature resistance, etc., different power taken by different current sensors, generally use Hall current sensor for current sampling;.
(2) current transformer: a wide range of current, generally use the BRS series current transformer;
3) Reactor.
Solar inverter working principle
Solar inverter consists of boost circuit and inverter bridge circuit, the boost circuit is mainly used to boost the DC voltage to the required DC voltage of the inverter output, and the inverter bridge circuit is mainly used to convert the boosted DC voltage into fixed frequency AC voltage. Therefore, the boost circuit and inverter bridge circuit complete the function of converting DC power to AC point.
Solar inverter has ten common faults and treatment methods
1、Grid abnormality
Grid abnormality is divided into grid voltage is too low, too high, grid frequency is too low, too high (corresponding to the error code F00-F03 respectively)
①Confirm whether the safety standard chosen by the machine meets the requirements of the local power grid.
② Check whether the AC output terminals are connected reliably and measure the voltage with a multimeter.
③ Disconnect the PV input, restart the machine and observe whether the machine can return to normal.
2、Low insulation impedance
Error code F07
① Disconnect the PV input, restart the machine, and observe whether the machine can return to normal.
② Check whether PV + and PV - to earth resistance is greater than 500KΩ.
③ If it is less than 500KΩ, please contact the local inverter distributor to help solve the problem, or contact the battery board supplier to deal with it.
3、Excessive leakage current
Error code F20
① Disconnect the PV input, restart the machine, and observe whether the machine can return to normal.
② Failure to solve the problem, contact the distributor.
4, The ambient temperature, radiator temperature is too high
Error code: F12, F13
① Disconnect the PV input, restart the machine after a few minutes to wait for the machine to cool down, and observe whether the machine can return to normal.
② Check whether the ambient temperature is beyond the normal operating temperature range of the machine.
5、Monitoring no data
WiFi monitoring:
Connect the inverter WiFi, check whether there is connected inverter in the monitoring page, if there is no inverter information, re-plug the built-in WiFi module or check the external WiFi RS485 connection; if you can't search the inverter WiFi, please check whether the built-in WiFi module has poor contact or the external WiFi is not powered.
GPRS monitoring:
Test the Internet signal strength of the same service provider at the inverter installation site, check whether the built-in GPRS module has poor contact or whether the external GPRS is not powered.
6、Low insulation impedance
Use the exclusion method. Pull down all the strings on the input side of the inverter, and then connect them one by one, use the function of inverter power-on detection of insulation impedance to detect the problem strings, find the problem strings and focus on checking the DC connector to see if there is a water-flooded shorting bracket or burnt fusion shorting bracket, and additionally check whether the component itself has a black spot burnt at the edge place leading to component leakage through the bezel to the ground network.
7、Leakage current failure
The root cause of this type of problem is the quality of the installation, choose the wrong installation location and low-quality equipment. There are many failure points: low-quality DC connectors, low-quality components, components installed at unqualified heights, grid-connected equipment of low quality or water leakage, but similar problems, you can find the leakage point in the leakage detection instrument and do a good job of insulation to solve the problem, if it is a problem of the province of the material can only replace the material.
8、Inverter power on no response
Please make sure that the DC input line is not connected to the reverse, generally DC connector has anti-dull effect, but the crimp terminal has no anti-dull effect, carefully read the inverter manual to ensure that the positive and negative poles before crimping is very important. The inverter has built-in reverse short-circuit protection, it will start normally after restoring normal wiring.
9、Grid fault
Grid over-voltage: Pre-survey of the grid heavy load (power consumption of large working hours) / light load (power consumption of less rest time) is reflected here, in advance to survey the health of the grid voltage, and inverter manufacturers to communicate with the grid to do a combination of technology to ensure that the project design within a reasonable range, do not "take for granted," especially the Rural power grids, inverters have strict requirements on grid voltage, grid waveform and grid distance. Most of the over-voltage problems are caused by the original grid light load voltage exceeding or close to the safety protection value, if the grid line is too long or poorly crimped, resulting in excessive line impedance / inductive impedance, the power plant can not be operated normally and stably. The solution is to find the power supply bureau to coordinate the voltage or correctly select the grid and pay close attention to the construction quality of the power station.
Grid under-voltage: This problem is the same as the treatment of grid over-voltage, but if there is an independent phase voltage is too low, in addition to the original grid load distribution is incomplete, the phase of the grid drop or disconnection can also lead to this problem, the virtual voltage.
Grid over/under frequency: If this type of problem occurs in a normal grid, it proves that the health of the grid is very worrying.
Grid No Voltage: Just check the grid tie lines.
Grid missing phase: check the missing phase circuit, that is, no voltage line.
10、 DC overvoltage protection
With the improvement of components in pursuit of high efficiency process, the power level is constantly updated to rise, while the components of the open-circuit voltage and operating voltage is also rising, the design stage must consider the temperature coefficient problem, to avoid low-temperature over-voltage lead to hard damage to the equipment.
