Solar inverter performance parameters

- Sep 17, 2018-

There are many parameters and technical conditions for describing the performance of the inverter. Here is only a brief description of the technical parameters commonly used in evaluating the inverter.

1. The environmental conditions of the inverter, the normal operating conditions of the inverter: the altitude is not more than 1000m, and the air temperature is 0~+40°C.

2. DC input power supply condition, input DC voltage fluctuation range: ±15% of the rated voltage of the battery pack.

3. The rated output voltage, within the allowable fluctuation range of the specified input DC voltage, indicates the rated voltage value that the inverter should be able to output. The stability accuracy of the output rated voltage value is generally as follows:

(1) In steady-state operation, the voltage fluctuation range should have a limit, for example, the deviation does not exceed ± 3% or ± 5% of the rated value.

(2) In the dynamic case of sudden load changes or other disturbance factors, the output voltage deviation should not exceed ± 8% or ± 10% of the rated value.

4. Rated output frequency, the frequency of the inverter output AC voltage should be a relatively stable value, usually 50Hz. Under normal working conditions, the deviation should be within ±1%.

5. Rated output current (or rated output capacity), which indicates the rated output current of the inverter within the specified load power factor range. Some inverter products give a rated output capacity, the unit of which is expressed in VA or kVA. The rated capacity of the inverter is the product of the rated output voltage as the rated output current when the output power factor is 1 (ie, purely resistive load).

6. Rated output efficiency, the efficiency of the inverter is the ratio of the output power to the input power under the specified working conditions, expressed in %. The efficiency of the inverter at rated output capacity is full load efficiency, and the efficiency at 10% rated output capacity is low load efficiency.

7, the maximum harmonic content of the inverter, sine wave inverter, under resistive load, the maximum harmonic content of the output voltage should be ≤ 10%.

8. The overload capacity of the inverter, under the specified conditions, the inverter output exceeds the rated current value in a short time. The overload capacity of the inverter should meet certain requirements under the specified load power factor.

9. Inverter efficiency, the ratio of the output active power of the inverter to the input active power (or DC power) at rated output voltage, output current and specified load power factor.

10. Load power factor, which characterizes the inverter's ability to carry inductive or capacitive loads. Under sine wave conditions, the load power factor is 0.7 to 0.9 (hysteresis) and the nominal value is 0.9.

11. The asymmetry of the load. Under the 10% asymmetric load, the asymmetry of the output voltage of the fixed-frequency three-phase inverter should be ≤10%.

12. The imbalance of the output voltage. Under normal working conditions, the three-phase voltage imbalance of the inverter output (the ratio of the reverse sequence component to the positive sequence component) should not exceed a specified value, generally expressed in %, such as 5 % or 8%.

13. Starting characteristics, under normal working conditions, the inverter should be able to start normally for 5 consecutive times under full load and no-load operating conditions.

14, protection function, the inverter should be set: short circuit protection, over current protection, over temperature protection, over voltage protection, under voltage protection and phase loss protection. The overvoltage protection means that for the inverter without voltage stability measures, there should be output overvoltage protection measures to protect the negative intercept from the output overvoltage. Overcurrent protection refers to the overcurrent protection of the inverter. It should be able to ensure that the load is short-circuited or the current exceeds the allowable value to prevent it from being damaged by the surge current.

15. Interference and anti-interference, the inverter should withstand the electromagnetic interference in the general environment under the specified normal working conditions. The anti-interference performance and electromagnetic compatibility of the inverter should comply with the relevant standards.

16. Inverters that are not frequently operated, monitored and maintained should be ≤95db; inverters that are frequently operated, monitored and maintained should be ≤80db.

17. It should be shown that the inverter should be equipped with data display of parameters such as AC output voltage, output current and output frequency, and display signal input with power, power and fault status.

18, communication function, remote communication function allows users to view the machine's operating status and stored data without having to go to the field.

19. The waveform distortion of the output voltage. When the inverter output voltage is sinusoidal, the maximum allowable waveform distortion (or harmonic content) should be specified. Usually expressed as the total waveform distortion of the output voltage, its value should not exceed 5% (single-phase output allows 10%).

20. Starting characteristics, which characterize the inverter's ability to start with load and performance during dynamic operation. The inverter should be guaranteed to start reliably under rated load.

21. Noise, transformers, filter inductors, electromagnetic switches and fans in power electronics will generate noise. When the inverter is in normal operation, the noise should not exceed 80dB, and the noise of the small inverter should not exceed 65dB.