Performance Evaluation of STATCOM for Voltage and Transient ‎Stability in Power Transmission Systems

Abstract

Modern power systems face challenges because of long-distance power transmission requirements, increasing power demand, and the widespread use of renewable energy sources. The research focuses on evaluating how Static Synchronous Compensator (STATCOM) systems improve voltage and transient stability assessment in power transmission networks. The research combines two methods which use both analytical techniques and simulation techniques to assess voltage stability through two indices (VSI and L-index) and critical clearing time (CCT) assessment and eigenvalue-based oscillation damping assessment. This study created mathematical models for STATCOM which include DC-link voltage dynamics and reactive power injection equations and they applied these models to a standard IEEE test system. The simulation results show that the installation of STATCOMs leads to a 25% to 40% improvement in voltage stability margin and it boosts minimum bus voltage from 0.82 p.u. to 0.95 p.u. under heavy loading conditions. Moreover, it extends CCT by 20% to 30% and shortens voltage recovery time by 35% to 50% and reduces low-frequency oscillation amplitudes by 40% to 60%. The quantitative findings, validated through time-domain simulation and eigenvalue analysis demonstrate that intelligent STATCOMs provide better results for transmission network stability than traditional compensation methods.

The increasing complexity of modern power systems, owing to long-distance load growth and large-scale integration of renewable energy sources, has created serious stability issues in power transmission systems. Voltage instability, transient instability, and lack of damping in low-frequency power swings are some of the major stability-related issues of critical concern in power systems. In addition, conventional reactive power compensation is not adequate under stressed conditions owing to poor controllability and dynamic response of reactive power compensators. This study aims at evaluating the potential of intelligent static compensators, such as Static Synchronous Compensators (STATCOMs), in improving power system stability.

This study is based on an analytical approach that combines power system stability and modern control concepts. The research is divided into three parts: (i) voltage stability enhancement, (ii) transient stability improvement, and (iii) low-frequency oscillation damping. The impact of intelligent static compensation is assessed using stability index and comparative performance evaluation. The study shows that intelligent static compensators, using smart control algorithms, have a significant impact on voltage profile improvement at weak buses, voltage stability enhancement, and reduction of voltage stability sensitivity. The research also shows that, under fault conditions, intelligent static compensators have a significant impact on critical clearing time extension and accelerated voltage recovery after faults. This shows that intelligent static compensators have a significant impact on transient stability improvement. The study shows that intelligent control of static compensators improves low-frequency oscillation damping, resulting in a reduction of oscillatory settling time. This improves overall performance and makes a stronger and more reliable power grid, especially under high-load conditions and renewable-rich regions.