What are the characteristics of how to classify three types of photovoltaic inverters?

As an important part of photovoltaic power generation, inverters are mainly used to convert the direct current generated by photovoltaic modules into alternating current. At present, the common inverters on the market are mainly divided into centralized inverters and string inverters, as well as trendy collector-distributor inverters. Today, Xiao Bian talked about the characteristics of each of the three inverters.

A centralized inverter

As the name implies, the centralized inverter converts the DC power generated by the PV modules into AC power and then boosts the voltage and connects them to the grid. Therefore, the power of the inverter is relatively large. Photovoltaic power plants generally use centralized inverters of more than 500 kW.

The advantages of a centralized inverter are as follows:

(1) Large power, small quantity, easy management; fewer components, good stability, and easy maintenance;

(2) Less harmonic content, high power quality, complete protection function, and high safety;

(3) Power factor adjustment function and low voltage ride-through function are available, and the grid regulation is good.

The problems of centralized inverters are as follows:

(1) The MPPT voltage range of the centralized inverter is narrow, and the operation of each component cannot be monitored. Therefore, it is not possible to make each component at the optimal operating point, and the component configuration is not flexible;

(2) The centralized inverter covers a large area, requires a dedicated machine room, and is inflexible to install;

(3) Its own power consumption and the power consumption of the ventilation and heat dissipation in the engine room are large.

Second, the string inverter

As the name implies, the string inverters convert the direct current generated by the PV modules into AC power and then boost the pressure and connect them to the grid. Therefore, the power of the inverter is relatively small. In photovoltaic power plants, string inverters of 50 kW or less are generally used.

String inverter advantages:

(1) It is not affected by the module differences among the strings, and the shaded shadows, and at the same time, the mismatch between the best working point of the photovoltaic cell assembly and the inverter is reduced, and the power generation amount is increased to the maximum extent;

(2) The MPPT voltage range is wide, and the component configuration is more flexible; in cloudy and rainy days, there are many areas where there is much fog, and the power generation time is long;

(3) Small volume, small footprint, no special machine room, and flexible installation;

(4) Low self-consumption and small effect of failure.

String inverter problems:

(1) The power device has a small electrical clearance and is not suitable for high altitude areas; there are many components and they are integrated together, and the stability is slightly poor;

(2) outdoor installation, wind and sun will easily lead to aging of the shell and heat sink;

(3) With a large number of inverters, the total failure rate will increase, making system monitoring difficult;

(4) Without isolation transformer design, the electrical safety is slightly poor, and it is not suitable for the negative-electrode grounding system of thin-film modules.

Third, the distribution inverter

The distributed inverter is a new form of inverter proposed in the past two years. Its main features are "centralized inverter" and "dispersed MPPT tracking." The distributed inverter is the product of the advantages of two types of inverters, a centralized inverter and a string inverter. It achieves the low cost of a centralized inverter and the high power generation of a string inverter. ".

Distributive inverter advantages:

(1) Compared with the centralized model, "Dispersed MPPT tracking" reduces the chance of mismatch and increases the amount of power generated;

(2) Compared with the centralized and string type, the distributed inverter has a boost function and reduces the line loss.

(3) Compared with the string-type, "concentration and contravariance" has more advantages in terms of construction costs.

Distributed Inverter Problems:

(1) Little engineering experience. As it is the newly proposed form in the past two years. After all, the application of engineering projects is still a minority;

(2) Safety, stability, and high power generation capabilities also need to undergo testing of the project;

(3) Because of the “centralized inversion”, the large footprint and the need for a dedicated machine room also exist in the distributed inverter.

The above is the classification and characteristics of photovoltaic inverters compiled by Xiaobian, and share with you. Inadequacies, please correct me.

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