Basic Circuit Model of Voltage Source Converters: Methodology and Modeling

The utilization of renewable energy sources for energy transition is gaining significant popularity due to pollution control and other environmental benefits. To move toward green energy generation, the integration of renewable energy sources with the existing conventional grid plays a key role. The performance of a modern interconnected power system, particularly with a high penetration of renewable energy sources, is significantly impacted by power system oscillations. Flexible Alternating Current Transmission System (FACTS) devices are recommended to improve control framework performance, and the power system stabilizer is the customary controller for damping such oscillations. FACTS offer a powerful strategy as they can control transport voltage, transmission line impedance, and power flows. This paper presents an efficient control scheme that combines four FACTS controllers: the static VAR compensator for controlling reactive power in control frameworks, the unified power flow controller for managing active and reactive power flows on transmission lines, the static synchronous compensator for maintaining system voltage stability, and the static synchronous series compensator for controlling transmission line impedance. To address the challenges posed by the variability of renewable energy sources such as wind and solar, the ant colony optimization algorithm is employed to optimally tune the controllers’ parameters. By generating controlled voltage and interfacing with the transmission line, these controllers enhance system stability, even under fluctuating renewable energy inputs. The IEEE 30-Bus system was used for simulation and control design, demonstrating the effectiveness of this approach in damping inter-area oscillations and improving the stability and resilience of a renewable-energy-integrated power system.

The integration of renewable energy sources (RESs) has become more attractive to provide electricity to rural and remote areas, which increases the reliability and sustainability of the electrical system, particularly for areas where electricity extension is difficult. Despite this, the integration of hybrid RESs is accompanied by many problems as a result of the intermittent and unstable nature of RESs. The extant literature has discussed the integration of RESs, but it is not comprehensive enough to clarify all the factors that affect the integration of RESs. In this paper, a comprehensive review is made of the integration of RESs. This review includes various combinations of integrated systems, integration schemes, integration requirements, microgrid communication challenges, as well as artificial intelligence used in the integration. In addition, the review comprehensively presents the potential challenges arising from integrating renewable resources with the grid and the control strategies used. The classifications developed in this review facilitate the integration improvement process. This paper also discusses the various optimization techniques used to reduce the total cost of integrated energy sources. In addition, it examines the use of up-to-date methods to improve the performance of the electrical grid. A case study is conducted to analyze the impact of using artificial intelligence when integrating RESs. The results of the case study prove that the use of artificial intelligence helps to improve the accuracy of operation to provide effective and accurate prediction control of the integrated system. Various optimization techniques are combined with ANN to select the best hybrid model. PSO has the fast convergence rate for reaching to the minimum errors as the Normalized Mean Square Error (NMSE) percentage reaches 1.10% in 3367.50 s.

Stochastic flexible transmission operation for coordinated integration of plug-in electric vehicles and renewable energy sources

This paper proposes a novel approach for Optimal Power Flow (OPF) problems in power systems by integrating the optimal placement of Flexible Alternating Current Transmission System (FACTS) devices with a hybrid renewable energy system comprising wind and photovoltaic (PV). The objective is to optimize the placement of FACTS devices to simultaneously minimize power loss, voltage deviation and reduce gross cost. To achieve this goal, the Enhanced Multi – Strategies Sparrow Search Algorithm (EMSSA) is employed, which combines multiple optimization strategies inspired by the collaborative foraging behavior of sparrows. By considering multiple objectives, including power loss reduction, voltage deviation reduction, and gross cost minimization, the proposed methodoloty aims to identify optimal locations for installing FACTS devices such as SVC (Static Var Compensator), TCSC (Thyristor Controlled Seris Compensator), TCPS (Thyristor Controlled Phase Shifter). The results showcase the capability of the proposed methodology to achieve significant improvements in power system performance, thereby contributing to the efficient and sustainable operation of modern power grids. This research also provides valuable insights for power system operators and planners to make decisions regarding the deployment of FACTS devices and the integration of renewable energy sources.

On small signal stability of an AC/DC power system with a hybrid MTDC network

A reactive scheduling and control framework for integration of renewable energy sources with a reformer-based fuel cell system and an energy storage device

Abstract-The modernization of the power grid, driven by the increasing integration of renewable energy sources, energy storage technologies, and electric vehicles, presents a critical challenge: maintaining grid stability. The intermittent power generation from renewables and the dynamic charging demands of EVs introduce imbalances that can lead to serious operational issues. While Voltage Source Converters (VSCs) are the key to integrating these technologies, their advanced functionalities are often underutilized. This paper proposes a novel control approach for a three-phase VSC that addresses this exact challenge. With only minimal modifications to the VSC's controller, our method enables the asymmetric distribution of power across the three phases. This capability allows for the VSC to mitigate grid imbalances actively, extending its basic function to become a key asset in maintaining network stability. The paper includes a detailed derivation of the controller and outlines its limitations. Both simulation and experimental validation are provided to demonstrate the simplicity and effectiveness of the proposed approach, highlighting its potential for integration into existing VSCs with minimal effort for maximum benefit.

Microgrid (MG) control in off-grid mode of operation is one of the main challenges in MGs. Under different loading conditions, voltage and frequency deviate from their nominal limits. The droop control method that applied with the current control and voltage control loops can restore the MG voltage and frequency to their nominal limits. However, it can’t regulate these parameters to their specified values. Additionally, the droop control method can’t do well when the system supplies either nonlinear or unbalanced loads. This paper proposes a control technique for adjusting the voltage and frequency of an MG in islanded mode under different loading conditions. The proposed method is based on applying the H-infinity ($$H\infty$$) robust control as a secondary controller with the droop control method to improve its performance. The proposed method is composed of four stages including; droop control loop, voltage control loop, current control loop and control loop for inductance–capacitance–inductance (LCL) filter and coupling circuit. $$H\infty$$ control has an internal model that can control the frequency and improve the system power quality by decreasing the disturbance frequencies. Moreover, it has two weighted parameters $$\xi$$ and $$\mu$$ that must be correctly adjusted to improve the stability of the system. For a proper adjusting of these parameters, the Harmony Search (HS) optimization method is applied. To prove the effectiveness and superiority of the proposed method, it is applied on a test system with three different loading scenarios using MATLAB/Simulink program. The results are compared with those of droop controller and they confirm that the proposed control method is more effective in controlling the microgrids under islanded mode operation.

Purpose of the Study. The study aims to investigate various approaches to mitigating the impact of renewable energy sources on the stability of the power system and to determine the optimal combination of conventional and renewable energy sources to ensure stable and reliable energy supply. The effectiveness of different approaches to minimizing the impact of renewable energy on grid stability is evaluated. Materials and Methods. Methods of eigenvalue analysis and transient process modeling were used. Correlation and regression analysis methods were used to assess the impact of renewable energy sources (RES) on the stability of the energy system. Data from the system operator «Ukrenergo» were used, including power system load schedules (hourly, daily, seasonal). Data from the Ukrainian Hydrometeorological Center for the years 2023–2024 were used to model RES generation: data on solar radiation (hourly, daily) and wind speed (hourly, daily). Technical specifications of solar panels and wind turbines installed in Ukraine were also used. The QGIS software was utilized for geoinformation analysis. The study employed artificial neural network theory, optimization methods based on linear programming and logical production rules, as well as methods for assessing and regulating steady-state operating conditions of the system, taking into account energy storage devices. Results. The scientific novelty lies in the development of an innovative method for assessing the reduction of the impact of renewable energy sources on power system stability. The feasibility of using artificial neural networks to forecast wind and solar power generation was demonstrated, as well as the optimization of the model structure and parameters to improve forecasting accuracy. The optimal combination of conventional and renewable energy sources was determined to ensure stable and reliable operation of the power system. Practical Significance. Based on experimental and theoretical research, specific recommendations and solutions are provided aimed at ensuring the stability of the power system during the integration of renewable energy sources, including optimization of management, use of new technologies, and infrastructure development

A central issue that was recently discussed within the power systems community is how the COVID-19 pandemic, and possibly other future pandemics, will affect the integration of renewable energy sources in the long-term. An interesting idea that may shed light on this question is the one of “economic shocks”, according to which, if the integration of renewable sources can be described as a dynamic system operating on time-scales of years, then several months of low consumption may be viewed as a negative impulse signal (a shock), which causes reactions and counter-reactions that evolve in a closed feedback loop. In this paper we explore this idea by means of a regression model, which attempts to reflect the relations between fossil-fuel based generation and day-ahead electricity prices and demand in the European market. The results point out to an interesting phenomenon of instability in fossil-fuel based generation following a shock in consumption, which may support the claim that pandemics and other economic shocks may promote the future integration of renewable energy sources.

Advancing sustainable energy systems—especially in rural areas and underdeveloped countries—depends on the integration of renewable energy sources into microgrids. This paper looks at the challenges connected to the integration of renewable energy sources—such as solar, wind, and hydro power—into microgrids as well as the recommended solutions to counterbalance these challenges. Along with innovative technologies and strategies that can enhance the efficiency and reliability of microgrid systems, issues such as intermittency, energy storage, grid stability, and system optimization are discussed. This paper also looks at the economic, technological, and regulatory factors influencing the establishment of renewable-powered microgrids and provides case examples demonstrating successful integration. Stressing the future potential for general adoption of renewable energy microgrids, the report concludes by underlining the significance of continuous research and government assistance in addressing present challenges.

<abstract> <p>This study proposes a centralized control system for an islanded multivariable minigrid to improve its performance, stability and resilience. The integration of renewable energy sources and distributed energy storage systems into microgrid networks is a growing trend, particularly in remote or islanded areas where centralized grid systems are not available. The proposed control system is designed to be implemented at two levels a high-level control system and a low-level control system. Hence, the high-level control system balances energy resources and demand, makes decisions for effective resource utilization and monitors energy transactions within the minigrid. Real-time data from various sources and advanced algorithms are used to optimize energy management and distribution enabling the integration of renewable energy sources and enhancing the resilience of the minigrid against power outages.</p> <p>Moreover, the low-level control system monitors energy parameters such as voltage, current, frequency and mechanical energy. The control system ensures these parameters remain within the specified range, maintaining system stability and ensuring efficient energy distribution. It also protects the minigrid against power outages improving system reliability and security. Finally, the proposed centralized control system offers a promising solution for improving the performance, stability and resilience of microgrid networks. The system provides real-time monitoring, efficient energy management and distribution, and the integration of renewable energy sources. These results have important implications for the development and deployment of microgrid networks in remote or islanded areas.</p> </abstract>

New features like high penetration level, low inertia, and weak damping are decreasing voltage support capacity in the power system as it sees large-scale renewable energy source (RES) integration continuously. The reasonable solution to this challenge is developing an additional active voltage regulation function for voltage source converters (VSCs). This study proposes a droop-based active voltage control strategy for VSCs in large-scale RES-integrated power systems to make VSCs continue to operate and regulate the voltage at the point of common coupling (PCC) during a fault without causing overcurrent. In order to meet the requirements of RESs and grid code, all control boundary conditions are designed based on practical engineering data. Meanwhile, plant uncertainty and parameter disturbance are introduced into a robust stability margin analysis model based on the component connection method (CCM) and structured singular value (SSV) to improve the engineering application prospect. The effectiveness and feasibility of this control strategy are proved by logical deduction and practical simulation based on a generalized small-signal model.

Power systems with high renewable energy sources: A review of inertia and frequency control strategies over time

GA-based optimization for integration of DGs, STATCOM and PHEVs in distribution systems