Instantaneous power of photovoltaic grid-connected inverter

What is a photovoltaic inverter control strategy?

The main objective of the inverter control strategy remains to inject the energy from the photovoltaic panels into the electrical grid. However, it is designed to inject this power through unbalanced currents so that the local unbalance introduced by the inverter contributes to the overall rebalancing of the grid’s total currents.

How to provide voltage support in PV inverter?

To provide voltage support at the PCC, reactive power is injected into the grid under fault conditions as per the specified grid codes. As previously discussed, the simultaneous injection of peak active power from PVs and reactive power into the grid for voltage support can trigger the over current protection mechanism in PV inverter.

What are the goals of grid-connected PV inverters?

Under grid voltage sags, over current protection and exploiting the maximum capacity of the inverter are the two main goals of grid-connected PV inverters. To facilitate low-voltage ride-through (LVRT), it is imperative to ensure that inverter currents are sinusoidal and remain within permissible limits throughout the inverter operation.

What is the output voltage of a PV inverter?

It is seen that the inverter is operating smoothly during the normal operating condition and the output voltage of 796.4 V power of 1504 kW (approximate) from PV power plant as well as grid parameters, i.e. grid voltage of 33 kV and grid power of 1 MW are also maintaining normally.

How do grid-tied PV inverters work?

When a fault (such as a short circuit, flickering, or loss of grid power) occurs on the grid, even if it is transient in nature, the conventional grid-tied PV inverters automatically cut themselves off from the grid. The inverters are configured in this fashion to prevent damage from transients of over current or over voltage.

What is the difference between a grid-connected inverter and a PV string?

The total extracted power from PV strings is reduced, while the grid-connected inverter injects reactive power to the grid during this condition. One of the PV strings operates at MPP, while another PV string is open-circuited to reduce its power to zero. Sag II: It consists of a three-phase voltage sag of 70%, as shown in Fig. 10a.