This thesis deals with the problem of control system design for power electronic controllers when high performance is desired despite unaccounted for internal and external conditions. Factors such as parameter variations, operating condition changes, and filtering and measurements delays, may adversely impact the performance of a circuit whose controller design is not immune to external and internal disturbances. The thesis explores the method of internal model design as a viable approach for designing controllers with superior performance despite system variations. Following a presentation of the theoretical background of the internal model design, the thesis considers two examples of state variable models, improving the stability of a voltage source converter and speed control of an induction motor. Conclusions show the new control system is more stable and offers better controllability despite unexpected system variations, compared to classical control system.

Large‐scale penetration of renewable resource based generation will displace conventional synchronous machine‐based power generation. This will lower the overall system inertia and will result in lower short circuit levels at point of connection (POC) of renewable resources. Renewable resources such as wind and solar photovoltaic (PV) are interfaced to the power system via power electronic inverters. Operation of inverter‐based equipment under low inertia and low short circuit conditions is challenging. Specific challenges include fault recovery response, unstable oscillatory interactions, and impact on torsional oscillations of thermal generating units. In this paper, the effectiveness of inverters, controlled as a virtual synchronous machine (VSM), to overcome some of these issues is investigated. A battery energy storage system (BESS) inverter is controlled as a VSM. The input signals provided to the BESS inverter are derived from solving the time domain equations of a synchronous machine. The response of exciter, governor, and power system stabilizer (PSS) are also included in the VSM strategy. The dynamic characteristics of the proposed VSM are verified using a single machine infinite bus (SMIB) test model. The effectiveness of the proposed VSM approach to mitigate specific technical challenges is verified by performing dynamic response studies on two test systems. The two test systems represent selected regions of practical power systems with high renewable penetration. The VSM response is compared with a conventional synchronous machine response in all test cases, to demonstrate the close correlation of dynamic response. The simulation results demonstrate that the VSM's response is as expected and is capable of mitigating stability‐related issues due to low system inertia and low short circuit strength.

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