Reactive power is in quadrature with active power and does not contribute in active power flow. DC power at the inverter input can be fully utilise to supply AC kW. Reactive power comes from the DC capacitor used at the inverter input.

Hi, according to power generation theory and IEEE-1547, reactive power generation follow quadrature rule and inverter capacity. Hence, it is not possible.

hi

Reactive energy is caused by the phase shift of current with respect to voltage. if the load has an inductive behavior, reactive energy appears. you must to correct it by adding capacitors or by didier control techniques for this phenomenon.

Dear Shaikat:

At the first, and as you know that an inverter is a power electronic device or circuitry that changes Direct Current (DC) electricity from sources such as batteries or fuel cells to Alternating Current (AC).

The input voltage, output voltage, frequency, and overall power handling depend on the design of the specific device or circuitry. The inverter does not produce any power; the power is provided by the DC source.

Power inverters are primarily used in electrical power applications where high currents and voltages are present.

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As for Reactive power is the power needed to keep the electric current flowing, and helps maintain voltage levels that are needed for system stability.

In the same way that we can think of real energy being stored in a battery, it is useful to think of reactive power as being stored within the electric field of a capacitor or the magnetic field of an inductor. To the degree that any circuit shifts the phase of the current to the voltage (and this can only apply to AC circuits), its impedance is said to have a reactive component. So, any circuit, including an inverter, that has an inductive or capacitive component to its impedance is temporarily storing reactive power in one or more of its components. An inverter often has a transformer as part of the circuit that attaches to an AC input and so is often an inductive load from the view of the power company.

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There is also another point to take into consideration which is the Renewable energy sources, such as solar power, provide not only electricity but can also be used to generate reactive power. To prevent blackouts, renewable energy systems also need smart inverters to control the energy flux and manage the passive power of electrical grids.

Reactive power does not do the work of electricity we all know, like lighting a lamp or heating water. Instead, the AC system consumes reactive power to keep electricity flowing.

As the amount of electricity flowing on a line increases, so does the amount of reactive power needed to move the additional electricity and maintain the proper voltage. The longer the distance power moves on a line, the more reactive power is consumed. When reactive power is insufficient, voltage drops. If it continues to drop, protective equipment will shut down affected power plants and lines to protect them from damage.

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As for the main point of your issue:

"How Power Inverter Generates Reactive Power" ... we can say the following:

We can use an inverter for reactive power generation. To deliver reactive power only, the voltage source connected to the main grid through a reactance has to generate a voltage in phase with the grid voltage but with higher amplitude. To absorb reactive power, it will generate a voltage still in phase with the grid voltage but with a lower amplitude.

Inverters generate reactive power by use of the freewheeling diodes on each of the power switches. The inductive nature of the load makes it want to draw current even after the power switch has been turned OFF. The load is shown as an induction motor but maybe the primary of a three-phase transformer or any other AC load. For an inverter to handle reactive power it must have the ability to run backward and absorb the reactive energy. This technology is called four-quadrant operation. The inverter can provide reactive power based on a function of the entire size of the inverter, not just on the level of generation. So, if cloudy skies drop solar generation from 100 percent to 10%, the inverter can use the other 90% of its remaining capacity to supply reactive power support and enhance utility grid power quality.

Reactive power control can be implemented in several ways – inverters can either be set to supply a specific ratio of active to reactive power, or set to dynamically match the reactive power requirements of the load as these change over time.

Inverter apparent power capacity is measured in Volt-Amps (VA). Historically, when inverters operated at unity power factor, the apparent power rating of an inverter (VA) was equal in value to the active power rating (W). So these terms were often used interchangeably. In the world of reactive power control, however, this is no longer the case, so the relationship between inverter capacity and active power needs to be clearly understood. Fortunately, it is a relatively simple relationship as shown in the following formula:

Inverter capacity x Power Factor = Active Power

Traditionally, PV Inverters were intentionally designed to feed as much active power (kW) as was available at unity power factor into the point of common coupling (PCC). More recently, utilities and independent power providers have shown tremendous interest in the three-phase inverter’s capability to also absorb and provide reactive power Q (kVAR) from and to the grid.

Over 95% of the time a PV inverter is running below its rated output current when converting DC solar power to AC active power. The unused capacity of the inverter can then be put to use to produce reactive power. The output of a smart PV inverter has both reactive and active AC currents that add geometrically to the apparent power, which will be limited by the current rating of the inverter.

There are many modern companies working on the production of such technology, such as GZ Industrial Supplies.

I hope it will be helpful...

With my best regards...

yes if inverter have dc link capacitors

Dear Hassan Nasser

Well explained answer. Only one doubt: Requirement of reactive power for the system is time independent and in that case utilization of unused capacity of Inverter may not match w.r.t. the time when it is available.

Hello Mohammed

DC electricity can only deliver active power however inverted AC electricity can deliver active and reactive power based on the phase displacement between the alternating current and voltage injected to the grid. Utilizing PV system as reactive power source to enhance the power quality of the grid had been researched in the literature, you can refer to this paper as it explains the process:

Article Grid-Connected PV System with Reactive Power Management and ...

Shaikat Debnath , if your converter is 100 kVA and has an active front-end (e.g. IGBTs), then it can deliver from 0 and up to 100kVAr of reactive power. A capacitor in the dc link would not even be necessary if there was no delay in the controllers and switches. Take a look at:

L. Malesani, L. Rossetto, P. Tenti, and P. Tomasin, “AC/DC/AC PWM converter with reduced energy storage in the DC link,” IEEE Trans. on Ind. Applicat., vol. 31, no. 2, pp. 287–292, Apr. 1995, doi: 10.1109/28.370275.

Article AC/DC/AC PWM converter with reduced energy storage in the DC link

But reactive power is much more than a "power factor". Distortion and harmonics (not only from your converter, but also from the grid) will produce reactive power as well. If you are interested, I recommend reading:

M. Godoy Simões, F. Harirchi, and M. Babakmehr, “Survey on time‐domain power theories and their applications for renewable energy integration in smart‐grids,” IET Smart Grid, vol. 2, no. 4, pp. 491–503, Dec. 2019, doi: 10.1049/iet-stg.2018.0244.

Article A Survey on Applicability of Instantaneous Power Theories an...

H. Akagi, E. H. Watanabe, and M. Aredes, Instantaneous power theory and applications to power conditioning. Hoboken, NJ: Wiley-Interscience, 2007.

P. Tenti, H. K. M. Paredes, and P. Mattavelli, “Conservative Power Theory, a Framework to Approach Control and Accountability Issues in Smart Microgrids,” IEEE Trans. Power Electron., vol. 26, no. 3, pp. 664–673, Mar. 2011, doi: 10.1109/TPEL.2010.2093153.

Article Conservative Power Theory, a Framework to Approach Control a...

No, an inverter does not generate reactive power from DC power. Reactive power is a component of AC power that does not contribute to real power flow. It is caused by the phase difference between the voltage and current in an AC circuit. Inverters convert DC power to AC power, but they do not create the phase difference that is necessary for reactive power to flow.

Reactive power can be generated by inductors and capacitors. Inductors store energy in a magnetic field and capacitors store energy in an electric field. When an inductor or capacitor is connected to an AC circuit, it alternately absorbs and releases energy. This causes the current in the circuit to lag or lead the voltage, depending on whether the inductor or capacitor is inductive or capacitive.

Inverters can be used to control the reactive power in a system. By adjusting the phase angle of the output voltage, inverters can be used to create leading or lagging reactive power. This can be used to improve the power factor of a system, which can reduce losses and improve voltage regulation.

Here are some additional details about reactive power:

• Reactive power is measured in kVAR (kilovolt-ampere reactive).
• Reactive power does not contribute to real power, which is measured in kW (kilowatts).
• Reactive power can cause voltage fluctuations and can lead to losses in the system.
• Reactive power can be controlled by using inductors and capacitors, or by using inverters.

I hope this helps!