Inverter is a kind of power adjustment device composed of semiconductor devices, mainly used to convert DC power into AC power, generally composed of boost circuit and inverter bridge circuit. The boost circuit boosts the DC voltage of the solar cell to the DC voltage required by the inverter output control; The inverter bridge circuit converts the boosted DC voltage into the common frequency AC voltage equivalently.
Inverter, also known as power regulator, can be divided into two types of independent power supply and grid-connected according to the use of inverter in photovoltaic power generation system. According to the waveform modulation mode, it can be divided into square wave inverter, step wave inverter, sine wave inverter and combined three-phase inverter. For the inverter used in the grid-connected system, according to the presence or absence of transformer can be divided into transformer type inverter and transformer type inverter. The main technical parameters of solar photovoltaic inverter are:
1. Rated output voltage
The pv inverter should be able to output the rated voltage within the allowed fluctuation range of the specified input dc voltage. Generally, when the rated output voltage is single-phase 220v and three-phase 380v, the voltage fluctuation deviation has the following provisions.
(1) In steady state operation, the voltage fluctuation deviation is generally required not to exceed ± 5% of the rated value.
(2) Voltage deviation shall not exceed ± 10% of the rated value in case of load mutation.
(3) Under normal working conditions, the unbalance degree of three-phase voltage output of the inverter should not exceed 8%.
(4) The distortion of the three-phase output voltage waveform (sine wave) should not exceed 5%, and the single-phase output should not exceed 10%.
(5) The inverter output AC voltage frequency under normal working conditions its deviation should be within 1%. The output voltage frequency specified in the national standard gb/t 19064-2003 should be between 49 and 51hz.
2, load power factor
The load power factor indicates the capacity of the inverter with inductive load or capacitive load. Under sine wave conditions, the load power factor ranges from 0.7 to 0.9, and the rating is 0.9. In the case of a certain load power, if the power factor of the inverter is low, the required inverter capacity will increase, leading to an increase in cost, at the same time, the apparent power of the photovoltaic system AC loop increases, the loop current increases, the loss will inevitably increase, and the system efficiency will decrease.
3. Rated output current and capacity
Rated output current refers to the rated output current of the inverter within the specified load power factor range (unit: A). Rated output capacity is the product of the rated output voltage and rated output current of the inverter when the output power factor is 1(i.e., a pure resistive load), in KVA or kW
Post time: Aug-20-2022
