BACKGROUND
The rapid growth of renewable energy sources poses various challenges for reliable operation of power grids. Many of these challenges stem from the inverter interfaces of these sources with the grid. The current/voltage of these inverter-based resources (IBRs) rely on their control systems, which are proprietary and can differ from one manufacturer to another. As a result, several grid codes have been developed in different jurisdictions to standardize the operation of IBRs and ensure reliability of the grid. A common provision of these grid codes and standards is that IBRs must remain connected to the grid and meet certain requirements for their current when the grid voltage drops. In a system with high penetration of renewable energy sources, failure to meet this requirement, commonly known as low-voltage ride-through (LVRT), can put the grid on the brink of instability and trigger blackouts.
TECHNOLOGY
The LVRT provision of recent progressive grid codes commonly require that IBRs prioritize the generation of certain levels of positive- and negative-sequence reactive currents and utilize the IBR’s remaining capacity to generate the maximum possible active current. The research team’s work has shown existing inverter control schemes fail to satisfy these requirements as stipulated in grid codes. This invention, however, ensures full compliance with emerging grid codes and standards. The result is a significant increase in the power generated by IBRs during LVRT conditions.
- A three-step algorithm has been developed to satisfy the grid code requirements for IBRs during LVRT.
- This invention is partly founded upon the discovery that increasing the positive-sequence active current may counterintuitively decrease the maximum phase current of an IBR.
- Another pillar of this invention enables an inverter to generate a large active current even when using its full current capacity to generate reactive currents.
- Depending the on grid conditions, the reactive current setpoints given by the grid code may violate the phase current limit of an inverter. Under such conditions, the reactive current setpoints need to be scaled down. The scaling factor given by this invention is quite larger than that given by existing technologies, thereby maximizing reactive currents as well.
BENEFITS
This invention enables inverter interfaces of renewable energy sources to generate significantly larger active and reactive currents during LVRT conditions. The increase in the active and reactive powers reaches up to 100% and 15% of the maximum power generated by existing methods, respectively. This would make power systems substantially more resilient during disturbances, reducing the risk of grid instability and blackouts.
APPLICATIONS
Reducing greenhouse gas emissions will hinge on decarbonization of power grids through a massive shift towards renewable energy sources. More than 80% of all new generating capacity added to power grids around the world in 2020 was renewable[1]. The transition towards renewable sources is expected to intensify in coming years. These sources are often connected to the grid through power electronic inverters. To ensure quick recovery from disturbances and to prevent outages, this invention ensures power electronic inverters remain in compliance with grid code and standards.
STATUS
- PCT filed in Spring 2023
- Seeking strategic partners for licensing and/or co-development
