Broadband Techniques in Dynamic Characterization and Adaptive Control of Static Synchronous Compensators

Abstract

The integration of power electronic converters into modern power systems has led to significant challenges in maintaining system stability and control performance, particularly under weak or dynamically changing grid conditions. Static synchronous compensators (STATCOMs) are widely deployed power electronic devices used to enhance power quality and provide fast dynamic support to the power grids. However, their performance is strongly influenced by network impedance and system operating conditions, which are often unknown or time-varying. Conventional control strategies, relying on offline tuning and fixed models, may fail to ensure robust operation across diverse grid scenarios.

This thesis addresses these challenges by developing and experimentally validating a unified framework that combines real-time broadband system identification with adaptive and hybrid control strategies tailored for grid-connected STATCOMs. Broadband frequency response measurements are performed using computer optimized binary sequences, enabling accurate characterization of the STATCOM over a wide frequency range with negligible disturbance. Building upon the real-time measurements of grid impedance and control bandwidth, novel adaptive control methods are developed to dynamically adjust controller parameters, enhancing system robustness. Additionally, a hybrid current controller is proposed by integrating proportional– integral (PI), deadbeat, and repetitive control techniques, ensuring fast transient response, high steady-state accuracy, and effective harmonics suppression. The proposed techniques are validated using power hardware-in-the-loop (PHIL) setups. Results show that the adaptive measures can improve STATCOM response time by up to 35 percent and DC-link dynamics by up to 72 percent, while the hybrid control can increase the control bandwidth by up to 150 percent and reduce harmonics by about 38 percent. These findings contribute toward more intelligent and resilient STATCOM systems capable of supporting the evolving needs of future power grids.