Why are LVRT (Low Voltage Ride Through) and HVRT (High Voltage Ride Through) used in solar inverters?

LVRT (Low Voltage Ride Through):

LVRT is a crucial feature that ensures solar-generating plants continue to operate even when there are short-term low-voltage conditions on the grid. Voltage dips can occur due to various factors, like grid faults or the connection of large loads.

In the past, renewable generating plants could disconnect from the grid during such voltage dips and attempt to reconnect later. However, with the increasing share of renewables, such disconnections could lead to grid instability or blackouts. LVRT mandates that these plants stay connected to the grid during these voltage disturbances, helping to maintain grid stability.

HVRT (High Voltage Ride Through):

HVRT addresses situations when there is a sudden increase in the DC link voltage or when demand is rapidly reduced, causing voltage at the Point of Common Coupling (PCC) to exceed its nominal value.

This could potentially damage PV inverters and lead to disconnection of grid-connected PV systems. HVRT capability is essential to handle high-voltage conditions on the grid side and prevent disruptions or islanding scenarios.

In summary, both LVRT and HVRT are crucial for ensuring the stability and reliability of the power grid and preventing power outages caused by voltage fluctuations. These are especially important with the increasing grid penetration of solar and renewable energy sources.