Design of a Resistive Brake Controller for Power System Stability Enhancement Using Reinforcement Learning

Computation of the closed-loop control laws, capable to realize multiple switching operations of a resistive brake (RB) aimed to enhance power system stability, is the primary topic of this brief. The problem is formulated as a multistage decision problem and use of a model-based reinforcement learning (RL) method, known as prioritized sweeping, to compute the control law is considered. To illustrate the performances of the proposed approach results obtained using the model of a synthetic four-machine power system are given. Handling measurement transmission delays is discussed and illustrated

Transient Stability Enhancement of Electric Power Grid by Novel Braking Resistor Models

The dynamic braking resistor is one of the effective methods to enhance the transient stability of power grid system. In this work, two new braking resistor models, namely, rectifier controlled braking resistor and chopper rectifier controlled braking resistor mod-els, using a single unit of braking resistor are proposed, and their performance is compared with the existing thyristor controlled braking resistor model. Comparison is made in terms of the speed indices, number of components used, heat loss, harmonics, and cost. The effectiveness of the proposed methodology is tested through Matlab/ Simulink simu-lations considering both temporary and permanent faults in power system. Simulation results for all braking resistor models are compared and analyzed. The performance of the proposed models is comparable to the existing braking resistor model. Therefore, the proposed braking resistor models can be considered as an alternative to the existing BR model for improving the transient stability of power systems

Hybrid Energy Storage Implementation in DC and AC Power System for Efficiency, Power Quality and Reliability Improvements

Battery storage devices have been widely utilized for different applications. However, for high power applications, battery storage systems come with several challenges, such as the thermal issue, low power density, low life span and high cost. Compared with batteries, supercapacitors have a lower energy density but their power density is very high, and they offer higher cyclic life and efficiency even during fast charge and discharge processes. In this dissertation, new techniques for the control and energy management of the hybrid battery-supercapacitor storage system are developed to improve the performance of the system in terms of efficiency, power quality and reliability. To evaluate the findings of this dissertation, a laboratory-scale DC microgrid system is designed and implemented. The developed microgrid utilizes a hybrid lead-acid battery and supercapacitor energy storage system and is loaded under various grid conditions. The developed microgrid has also real-time monitoring, control and energy management capabilities. A new control scheme and real-time energy management algorithm for an actively controlled hybrid DC microgrid is developed to reduce the adverse impacts of pulsed power loads. The developed control scheme is an adaptive current-voltage controller that is based on the moving average measurement technique and an adaptive proportional compensator. Unlike conventional energy control methods, the developed controller has the advantages of controlling both current and voltage of the system. This development is experimentally tested and verified. The results show significant improvements achieved in terms of enhancing the system efficiency, reducing the AC grid voltage drop and mitigating frequency fluctuation. Moreover, a novel event-based protection scheme for a multi-terminal DC power system has been developed and evaluated. In this technique, fault identification and classifications are performed based on the current derivative method and employing an artificial inductive line impedance. The developed scheme does not require high speed communication and synchronization and it transfers much less data when compared with the traditional method such as the differential protection approach. Moreover, this scheme utilizes less measurement equipment since only the DC bus data is required