Constrained Voltage Compensation in Ring Power Network using Series Capacitor for a Hybrid Multi-Source with a 2500MVA Grid Connected System

• A hybrid ring-configured microgrid architecture is proposed, in which multiple generation sources -including two renewable and conventional main grid- operate simultaneously. The study systematically analyzes voltage instability phenomena arising from continuous fluctuations in renewable power output, which may escalate to severe voltage collapse and, in extreme cases, system-wide blackout conditions. To the best of the authors’ knowledge, voltage compensation using series capacitor in hybrid ring microgrids under sustained renewable intermittency has not been comprehensively investigated in existing literature. Some articles mention the voltage drop problem in ring networks, but none have included multi-source generation, including more than one renewable energy source, nor have they solved the problem using series capacitors. • Two distinct SCC based methodologies are formulated to mitigate voltage drops in distribution level microgrids. The proposed methods are designed to restore the voltage levels of the load bus to the constrained limits while at the same time reducing the magnitude of the line currents that will lead to a decrease in the feeder losses. • Multiple operating scenarios for the variation of the load power factor have been evaluated to test the performance of the SCC methods. To assess the steady state voltage behavior, a detailed time domain simulation had been done using MATLAB/Simulink software. • To support the long-term effectiveness and the practical applications of the SCC, continuous 12-month profiles are tested, capturing seasonal variations in the renewable energy generation and load demand. The resulting voltage profiles and power flow characteristics are analyzed over a full annual cycle. • A comparative assessment between ring and radial /tree network topologies is performed to quantify their relative advantages. The comparison demonstrates the superior voltage regulation capability and reduced cable losses achievable with the ring configured microgrid under high renewable penetration. Microgrids nowadays are affected directly by the voltage instability, bad voltage profiles (especially large load demand with the high variation of generation in renewable energy distributed sources), and unmoderated line losses. The inverter base interface with the intermittency of the renewable energy sources increases these challenges. Renewable energy generations produce a fluctuating power opposite to that of the conventional synchronous generators. Voltage stability suffers from those characteristics specifically in weak or low-inertia power systems such as microgrids. Extensively, series capacitor compensation (SCC) has been used in power transmission lines to improve power transfer capability, enhance voltage profile, and reduce the effective reactance of the line. Large-scale power systems are good evidence to highlight the SCC's effectiveness in solving voltage drops and improving the steady-state voltage stability. However, existing literature shows a limited attention toward the application of SCC for voltage improvement, especially in ring power networks, while the growing complexity and challenges of modern power networks with the increased involvement of renewable energy sources that have a high penetration have been sharply increased. This paper presents a constrained scope for sizing and placement of series capacitors in a hybrid alternating current (AC) microgrid with two renewable energy sources connected to the main grid. The aim of this study is to improve the steady-state voltage stability, reduce line losses, and enhance the load voltage profiles within the variation power from the two renewable energy sources. The constrained enhancement of the voltage level in this paper is set to be up to 5% of the load rated voltage. Through detailed simulations of a representative hybrid micro grid with renewable penetration, the efficacy of the proposed approach has been demonstrated. Results reveal significant improvements in voltage regulation, a marked reduction in active power losses, and enhanced resilience to intermittent generation. Thus, in this research, the application of series compensation for improving a continuous twelve months’ voltage profile within ring power hybrid micro grid, loaded by several scenarios using MATLAB/Simulink software are studied, to mitigate voltage drops, strengthen weak buses, and reduce cable power losses. On the other hand, a comparison study between radial, tree and ring networks had been done to highlight the advantages of the ring microgrids over the other types. To the authors’ knowledge, the present paper is the first to successfully reduce the voltage drop to its acceptable levels in two renewable energy sources operating simultaneously with the main grid in a ring microgrid using series capacitors.