Graduate Thesis Or Dissertation


Inverter Current Limiting Impacts on Power System Stability Public Deposited
  • The need to keep the average global temperature increase to less than 1.5 °C combined with the decline in the cost of renewable energy technologies has led to an increase in the number of energy sources that have been connected to the power grid through inverters, called inverter-based resources (IBR). Because inverters are made using semiconductor switches that cannot withstand high current levels, they must have a method to limit the current that can pass through the device. This method is usually implemented digitally and is called a current limiter. While current limiters are not new, their impact on overall power system stability has not been fully explored. In addition, existing positive sequence modeling tools cannot capture fast inverter dynamics, and while electromagnetic transient studies can, studying large systems quickly becomes computationally intractable. Because of this, studying inverter interactions in large systems has been a challenge that limits our understanding of the behavior of the future power grid. A new open-source modeling tool called Sienna, built on the direct-quadrature-zero (dq0) model, is being developed to address this problem. The work in this thesis contributed instantaneous and magnitude current limiting models to Sienna and then explored the conditions under which these current limiters would cause a 14-bus system to become large signal unstable using grid forming (GFM) and grid following (GFL) IBR interacting with synchronous machines. The research found that the magnitude current limiter was less likely to cause large signal instability and that the pre-disturbance reactive conditions affected when the current limiter drove instability. It also found that a GFM IBR may enter a limit cycle when it reaches its current limit and there are synchronous machines on the system, and that there is a scenario when an unstable GFM IBR can trigger an additional source of instability in a GFL IBR. This demonstrates the importance of fully exploring how control structures like current limiting will behave and interact in a larger system.

Date Issued
  • 2023-08-07
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Last Modified
  • 2024-01-18
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