What are the key grid code requirements relating to fault ride-through capability for offshore wind farms?

Fault ride-through (FRT) capability is a critical requirement in grid codes for offshore wind farms. Grid codes are sets of technical standards that define the performance requirements for connecting to the electrical grid. FRT refers to the ability of a wind farm to remain connected to the grid and continue operating during and after a grid fault, such as a voltage dip caused by a short circuit. The key FRT requirements typically specify the minimum voltage level and the maximum duration for which the wind farm must remain connected. For example, a grid code might require that a wind farm must stay connected to the grid even if the voltage dips to 20% of its nominal value for up to 150 milliseconds. The specific requirements vary depending on the grid code of the country or region where the wind farm is located, but the general principle is the same: wind farms must not disconnect from the grid during faults, as this can exacerbate the problem and lead to wider grid instability. In addition to remaining connected, wind farms are often required to provide active and reactive power support during faults. Active power support helps to maintain the frequency of the grid, while reactive power support helps to stabilize the voltage. The grid code may specify the amount of active and reactive power that the wind farm must inject into the grid during a fault and the speed at which it must respond. Furthermore, wind farms are typically required to have control systems that can automatically adjust their power output to meet the grid's needs. This includes the ability to reduce power output during periods of high grid demand or to increase power output during periods of low grid demand. The wind farm must also be able to withstand temporary overvoltages and overfrequencies without disconnecting from the grid. These requirements are designed to ensure that wind farms contribute to the stability and reliability of the electrical grid, rather than exacerbating problems during faults. Compliance with FRT requirements is typically verified through simulations and field tests. Wind farms must demonstrate that they can meet the grid code requirements before they are allowed to connect to the grid. In summary, FRT capability is a crucial requirement for offshore wind farms, ensuring that they remain connected and provide support to the grid during fault conditions, contributing to overall grid stability and reliability.