Inverter as the detection center of the entire power plant, on the DC component, the next pair of grid-connected equipment, all the basic power plant parameters can be detected through the inverter. The basic information of the power station provided by the inverter covers: DC voltage, DC current, insulation resistance of DC to ground, DC leakage detection of AC power station, AC voltage, AC current, AC frequency, and AC phase sequence detection.
Generally, as long as the inverter is connected to the grid, the power curve displayed by the monitoring is a normal “hill†line, which proves that the power station is operating stably. If an abnormality occurs, the health status of the auxiliary equipment of the power station can be checked through the information fed back by the inverter. The following lists the basic information and processing methods:
Basic information and processing methods
1. Low insulation resistance: Use exclusion method. Unplug all the strings on the input side of the inverter, and then connect them one by one. Use the function of the inverter to detect the insulation resistance, detect the problem strings, and then check whether the DC connectors have flooding short-circuit brackets after finding the problem strings. Alternatively, the shorting brackets can be melted and the components themselves can be checked to see if there is a black spot on the edge and the components are leaked to the ground through the frame.
2. The bus voltage is low: If it is in the early/late hours, it is a normal problem because the inverter is trying to limit the power generation conditions. If it is in the normal daytime, the detection method is still the exclusion method, and the detection method is the same as the 1 item.
3. Leakage current failure: The root cause of this type of problem is the installation quality problem, which is caused by the wrong installation location and low quality equipment. There are many points of failure: low-quality DC connectors, low-quality components, unsatisfactory installation height of components, low quality of grid-connected equipment, or leakage of incoming water. Once similar problems occur, you can find out the Good insulation work to solve the problem, if it is the province of the material problems can only replace the material.
4, DC overvoltage protection: With the pursuit of high-efficiency process improvement of the components, the power level is constantly updated, and the open circuit voltage and the operating voltage of the components are also rising. The temperature coefficient must be considered in the design stage to avoid overvoltage in the low temperature condition, resulting in hard equipment. damage.
5. The inverter does not respond to power on: Make sure that the DC input circuit is not reversed. Generally, the DC connector has a fool-proof effect. However, the crimping terminal has no foolproof effect. Read the inverter instructions carefully to ensure that the positive and negative terminals are crimped. very important. Inverter built-in reverse short-circuit protection, normal start after restoring normal wiring.
6, power grid failure:
Overvoltage in power grid: The work of pre-investigating power grid heavy load (large working hours for power consumption)/light load (reduced power consumption time) is reflected here, and the health status of voltage points at the outlets is surveyed in advance, and the inverter manufacturers Communicating the situation of the power grid and combining technology can ensure that the project design is within a reasonable range, and do not “take it for grantedâ€, especially for rural power grids, inverters with grid voltage, grid-connected waveforms, and grid-connection distances are all strictly required. The majority of power grid overvoltage problems occur because the original power grid light load voltage exceeds or approaches the safety protection value. If the grid connection line is too long or the pressure connection is not good, the line impedance/inductance is too large, and the power station cannot operate normally. The solution is to find the power supply bureau to coordinate the voltage or to properly select the grid connection and strictly control the quality of the power station construction.
Grid undervoltage: This problem is consistent with the grid overvoltage treatment method, but if an independent one-phase voltage is too low, in addition to the original grid load distribution is incomplete, the phase grid power loss or open circuit can also cause the problem, Virtual voltage.
Grid over/under frequency: If the normal grid has such problems, it proves that the grid health is very worrying.
The grid has no voltage: check the grid connection.
Grid phase missing: Check for missing phase circuits, ie no voltage lines.
(Information reference point, inverter AC parameter monitoring page, and the grid-connected inverter output current according to the grid waveform, so the AC information shows the health of the grid, the DC information is the health information of the components, the grid-connected inverter The device serves as an integrated device for the energy conversion unit and the power station detection unit.
Three-phase imbalance
Grid-connected line plus special equipment causes abnormal grid connection
Long-distance grid-connected, grid overvoltage phase shift
7, the last point - monitoring lap: the correct reading of the device manual model circuit crimping, device connection, and set the device's communication address, time, is to ensure stable and effective communication guarantee!
8, power generation guarantee: free to wipe the board, power generation "convex" it up.
In fact, for a power plant, many problems arise when the problem is not caused by the inverter itself, but related to other equipment or installation methods, so the early selection and installation also need to pay attention to everyone.
The design of the azimuth angle of inclination, the design of the distance between components, the location of the installation site, the health check of the grid voltage, etc. also determine the performance of the power plant operation and power generation in the following 25 years. It can be said that the overall quality of the power station is determined by the material and installation quality of the power station!
1. Components: The A-class board is selected, and the judgment basis is determined by the price, and low-quality and low-quality products are rejected, for example, the gate line is bad.
2. Bracket: Use anti-corrosion brackets, components at least 30cm from the ground, such as ...
3, grounding flat steel: according to the size of the system correctly design and configure the grounding project, very important
4, DC terminal: very important material, poor quality of the terminal will often lead to a single point of contact with the terminal core to cause overheating and melting, and the terminal with a poor waterproof will lead to false short circuit and leakage of the terminal and the bracket in rainy days. Xiao Bian does not post the burned situation, leaving some room for imagination.
5, DC cable: The correct choice of cable model size, design honor should not be too small or too large, usually 1.2-1.5 times. Too small current carrying capacity is not enough. It is forbidden to use the "family line" casually.
6. Inverter: The inverter with excellent quality is selected. The installation of the inverter must pay attention to heat dissipation. At present, the inverter is installed with IP65 outdoors. It is recommended not to install it in a narrow room, especially for residential customers, to avoid the problem of heat dissipation. Equipment operation noise, correct reading instructions is the best choice.
7, AC cable: The correct choice of cable size, design honor should not be too small or too large, usually 1.2-1.5 times. Too small current carrying capacity is not enough.
8. Cable Bridge: A good power station will always be neat and tidy. Whether it is a bridge or a simple fixing method, it will determine the aesthetic level and durability of this power station.
9. AC grid-connected equipment: eliminate cutting-edge materials, properly select grid-connected switches and lightning protection equipment, and properly design grid-connected lines to ensure reliable operation of the system.
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