Detailed explanation of PV grid-connected inverter parameters - power factor

The power factor of the photovoltaic grid-connected inverter is a point that has to be mentioned in the technical parameters. In an AC circuit, the cosine of the phase difference (Φ) between the voltage and the current is called the power factor, which is represented by the symbol cosΦ. In terms of value, the power The factor is the ratio of active power to apparent power, that is, cosΦ=P/S. Generally speaking, the power factor of resistive loads such as incandescent bulbs and resistance furnaces is 1. Generally, the power factor of circuits with inductive loads is less than 1. When the power factor of the equipment is less than 0.9, it will be fined.

The power factor output of the photovoltaic grid-connected inverter is required to be 1, and it can be adjusted between 0.8 leading and 0.8 lagging.

Power factor is a special concern for industrial and commercial distributed photovoltaic projects. It needs to be considered from the perspective of the system, not only the type and size of the load, but also the performance of the reactive power compensation device, test points and control methods. It is recommended to observe The operation of the entire photovoltaic system ensures that the active power of the system is normal.

What kind of parameter is the power factor? It can directly affect the calculation of electricity bills! Let's first look at the electricity company's electricity bill calculation method for industrial users:

Total electricity fee = active energy electricity fee + basic electricity fee + power factor adjustment electricity fee

In practical life applications, as long as there is an inductive load or a capacitive load, reactive power will be generated. The power loads in the power grid, such as motors, transformers, fluorescent lamps and electric arc furnaces, are mostly inductive loads. These inductive devices During operation, it is not only necessary to absorb active power from the power system, but also absorb reactive power at the same time. In addition any converter capable of storing and releasing energy can also generate reactive power. Too much reactive power will result in too low power factor, and thus be fined.

What should we do? At this time, we need to perform reactive power compensation. The purpose and energy-saving effect of reactive power compensation are to reduce load current, reduce line loss, improve power factor, and reduce electricity costs.

The main purpose of reactive power compensation is to improve the power factor of the compensation system. Because the electricity sent by the power supply bureau is calculated in kVA or MVA, but the charge is in kW, that is, the actual useful work done. There is a difference between the two inactive power, generally speaking, it is Reactive power in kvar.