Model reference adaptive control algorithm for power system interarea oscillations damping

Abstract

Low-Frequency Electromechanical Oscillations (LFEOs) represent a real threat to power system networks as they are the primary cause of inter-area oscillations and because they limit the generation’s output. Mitigating their effects is therefore crucial as it may lead to system collapse if not properly damped. As Rotor angle instability is the primary cause of LFEOs, this thesis presents a novel Model- Reference Adaptive Control scheme that enhances its stability. The proposed scheme is tested using the Single-Machine Infinite Bus (SMIB) network. Communication between the Real-Time Digital Simulator (RTDS) and SEL-3555 RTAC is done using the IEC 61850 communication standard. The results obtained validate the proposed decentralized control architecture. The robustness of the proposed interarea oscillations damping controller is verified through a Hardware-in-the-Loop (HIL) Lab-scale implementation comprising of the RTDS, SEL-3555 RTAC, SEL-3355 rugged computer. The system modelling and simulation are performed in the RSCAD software whilst the RTDS GTNET card in conjunction with the SEL-3555 controller are used for Analog GOOSE messages exchange between the system and the controller. With Gaussian noise added as input to the generator to emulate small load variations responsible for the rotor angle instability, the results showed that the rotor angle remain stable. Furthermore, when subjected to faults, the recovery time is less than 500 ms. Lastly, a comparison between the results previously obtained through digital simulation via the MATLAB/SIMULINK software is carried out. This thesis deliverables contribute to opening and bringing the knowledge behind Model- Reference Adaptive Control (MRAC) and its application in power system in conjunction with the IEC 61850 standard as follows: • Power system small signal rotor angle stability enhancement. The developed testbed shows that the stability of the rotor angle can be guaranteed irrespective of the contingencies. • Application of the IEC 61850 standard in a MRAC control strategy for power system small signal stability studies. Analog GOOSE messages are utilized for data exchange between the power system and the controller thus leveraging the interchangeability, interoperability, future proofing, and security that this communication protocol brings. The developed algorithm can therefore be used in a different controller provided it is IEC 61850 compatible with little or no changes. • Development of control and automation devices for smart grids by Original Equipment Manufacturers (OEMs). The proposed algorithm can be incorporated into Intelligent Electronic Devices (IEDs) for instance to work in conjunction with power system stabilizers and the synchronous generator excitation systems.