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The substantial potential for the integration of renewable energy into power systems using power electronics converters might result in stability issues because of a lack of inertia. For this reason, this study introduces the concept of a virtual synchronous machine (VSM) control algorithm that emulates the properties of traditional synchronous machines. The literature includes references to several differently structured control algorithms. However, synchronous machine inertia and damping characteristics must be mimicked, which makes the cost and simplicity of implementation important from an economic perspective. This study presents a comprehensive comparison of VSM control algorithms. The most significant factor investigated in the work presented in this study is the viability of VSM algorithms during the kind of abnormal operation that might raise instability issues with respect to practical discrete time operation. The test system used in this study, which was simulated in a PSCAD/EMTDC environment, consisted of simulated voltage source converters based on a fully detailed switching model with two AC voltage levels. The results indicate a significant outcome that can facilitate a determination of the most effective VSM control algorithm.
This work presents a multiphase ac–dc converter-based electric vehicle (EV) charging station that is designed to meet IEEE-519 power-quality (PQ) standard. The proposed EV charging station draws current from the utility grid at low total harmonic distortion (THD) and high power factor (PF), without using PF corrector and active/passive filter circuits. This study evaluates an 18-phase ac–dc converter for an EV charging station, which consists of three single-phase multiwinding transformers (MWTs) and diode rectifiers. MWTs are connected to enable direct conversion of a three-phase utility supply into an 18-phase power supply that reduces the measured THD in the input line current. The ac–dc conversion stage of the proposed EV charging station is found to be reliable and operates at line-frequency, without the need for high-frequency active switches. For charging an EV in constant current (CC) and constant voltage (CV) mode, a multiphase (interleaved) dc–dc converter is used. MATLAB/Simulink environment is used to evaluate the performance of the proposed EV charging station in terms of THD and PF. The results are validated through an on-the-bench prototype hardware setup of the proposed EV charging station.
The integration of renewable energy resources into the electrical distribution systems faces several stability challenges especially in the low inertia conditions. To address these issues, this study introduces a virtual synchronous machine (VSM) control strategy for the intertying power electronic converters in the autonomous AC/DC hybrid microgrids. It is shown that the VSM‐based controller improves the system damping following the frequency disturbances and the AC/DC voltage variations. Moreover, a power management regulation topology is implemented in the active intertying converter to achieve an accurate bidirectional power flow under different loading conditions. A small‐signal state‐space model for the entire hybrid system is developed to assess the overall system performance. Time‐domain simulation results under the PSCAD/EMTDC environment are also presented to investigate the effectiveness of the proposed techniques. The introduction of the VSM control for the intertying converters in the hybrid AC/DC microgrids provides a significant improvement in the dynamic performance and increases the robustness against external disturbances.
Abstract Deployment of fast‐charging stations for electrified transportation is currently one of the limiting factors in the commercial deployment and paradigm shift of the mobility sector. The rapidly increasing demand for electric vehicles (EVs) brings the demand for accessible and affordable charging infrastructure. The commercial EV fast‐charging load profile depends on the customer's EV charging demand, which poses challenges in determining the overall peak profile. This could lead to unprecedented challenges of harmonic disruption, system losses, supply‐demand balance, and grid reliability. The emergence of bidirectional charging infrastructure and the realization of controlled charging strategies in coordination with the cumulative contribution of renewable energy resources could potentially reduce the challenge of utility grid stability and reliability shortly. Furthermore, the parallel development of smart grid technologies has promising features. This paper aims to provide a comprehensive state‐of‐the‐art review of the major challenges of the utility grid in the swift adoption of fast charging infrastructures available in the open literature, as well as the sustainable implications and potential safety measures. Furthermore, the potential solutions and best practices for the synchronization of electrified transportation with the emerging ecosystem of renewable power systems and various controlled charging strategies are reviewed in detail.
The high potentiality of integrating renewable energies, such as photovoltaic, into a modern electrical microgrid system, using DC-to-DC converters, raises some issues associated with controller loop design and system stability. The generalized state space average model (GSSAM) concept was consequently introduced to design a DC-to-DC converter controller in order to evaluate DC-to-DC converter performance and to conduct stability studies. This paper presents a GSSAM for parallel DC-to-DC converters, namely: buck, boost, and buck-boost converters. The rationale of this study is that modern electrical systems, such as DC networks, hybrid microgrids, and electric ships, are formed by parallel DC-to-DC converters with separate DC input sources. Therefore, this paper proposes a GSSAM for any number of parallel DC-to-DC converters. The proposed GSSAM is validated and investigated in a time-domain simulation environment, namely a MATLAB/SIMULINK. The study compares the steady-state, transient, and oscillatory performance of the state-space average model with a fully detailed switching model.
This extensive review article provides a comprehensive analysis of control strategies for power sharing in Multi-Terminal High Voltage Direct Current (MT-HVDC) systems utilizing voltage source converters (VSC) and multi-level modular converters (MMC). MT-HVDC systems have become essential components of modern power infrastructures due to their ability to efficiently transmit energy over long distances, connect renewable energy sources, and enhance grid stability. Effective power sharing control is of uttermost importance in these systems for ensuring equitable energy distribution between terminals and grid reliability. The paper begins with a thorough explanation of the fundamental concepts underlying MT-HVDC systems, emphasizing their significance, and examining the various configurations of such systems. The discussion then examines the functions of VSCs and MMCs in these systems, highlighting their distinct advantages and applications. The review analyses in depth the complex power sharing control strategies within VSC-based and MMC-based multi-terminal HVDC systems, as well as a number of control methods, algorithms, and optimization techniques. In addition, the article discusses difficulties and solutions associated with power sharing control in MT-HVDC systems, such as communication and synchronization issues.
In the context of integrating Renewable Energy Sources, Microgrid (MG) development is pivotal, particularly as a foundational technology for Smart-Grid evolution. Despite advancements in control techniques, challenges persist in ensuring system stability and accurate power sharing across diverse operational conditions and load types. The objective of this research is to control numerous paralleled inverters-based distributed generators (DGs) that contribute to power sharing in an island MG. The proposed methodology involves developing an innovative small-signal model for islanding MGs that incorporate virtual impedances. Subsequently, optimization algorithms based on Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) are proposed and compared for designing the virtual impedances. These algorithms analyze all potential operating points, aiming to minimize reactive power mismatches while maximizing MG stability. The suggested objective function facilitates the simultaneous achievement of these objectives. The proposed approaches were tested using MATLAB-Simulink software, and the comparison of the results between conventional approach and the proposed optimal approaches shows significant improvement in terms of the dynamic response during load changes, such as a decrease in response time by up to 20%, a reduction in overshoot percentage by approximately 15%, and a settling time improvement of nearly 25%. These quantified improvements highlight the effectiveness of the GA and PSO methods in minimizing the reactive power-sharing error while optimizing MG performance and stability.
The substantial potential for the integration of renewable energy into distribution power systems, through the use of power electronics converters, might result in instability due to a lack of inertia. For this reason, this paper introduces the benefit of a virtual synchronous machine (VSM) control algorithm that emulates the properties of traditional synchronous machines in the hybrid microgrid. This paper presents a novel control of the interlinking converter based VSM with an autonomous power sharing capability. The most significant factor investigated in the work presented in this paper is the power exchange from the AC into DC microgrid, and vice versa. The test system used in this study, which was simulated in a PSCAD/EMTDC environment, consisted of simulated voltage source converters based on an average model. The results indicate a significant outcome of the system performance that can achieve the benefit of considering VSM control algorithm in the interlinking converter in Hybrid microgrid.
Electric vehicles (EVs) are not only a viable energy efficient mode of transport, but they have considerable capacity of providing flexible and quick responding storage alternative based on vehicle-to-grid (V2G) scheme. V2G technology facilitates bidirectional flow of energy to and from the vehicle by a power converter. However, there is skepticism regarding the economic profitability of the V2G scheme. Despite the aforementioned challenges, the V2G technology is explored in matured markets. A number of V2G pilot projects across the world have investigated different aspects of V2G integration such as technological readiness, economic feasibility, social benefits, and challenges of V2G. This work aims to review the existing pilot projects on V2G functionality.
<title>Abstract</title> Maintaining a power balance between generation and demand is generally acknowledged as being essential to maintaining a system frequency within reasonable bounds. This is especially important for linked renewable-based hybrid power systems (HPS), where disruptions are more likely to occur. This paper suggests a prominent modified "Fractional order-proportional-integral with double derivative (FOPIDD2) controller" as an innovative HPS controller in order to navigate these obstacles. The recommended control approach has been validated in power systems including wind, reheat thermal, solar, and hydro generating, as well as capacitive energy storage and electric vehicle. The improved controller's performance is evaluated by comparing it to regular FOPID, PID, and PIDD2 controllers. Furthermore, the gains of the newly structured FOPIDD2 controller are optimized using a newly intended algorithm terms as squid game optimizer (SGO). The controller's performance is compared to benchmarks such as the grey wolf optimizer (GWO) and jellyfish search optimization. By comparing performance characteristics such as maximum frequency undershoot/overshoot, and steadying time, the SGO-FOPIDD2 controller outperforms the other techniques. The suggested SGO optimized FOPIDD2 controller was analyzed and validated for its ability to withstand the influence of power system parameter uncertainties under various loading scenarios and situations. Without any complicated design, the results show that the new controller can work steadily and regulate frequency with an appropriate controller coefficient.
Power sharing among multiterminal high voltage direct current terminals (MT-HVDC) is mainly developed based on a priority or sequential manners, which uses to prevent the problem of overloading due to a predefined controller coefficient. Furthermore, fixed power sharing control also suffers from an inability to identify power availability at a rectification station. There is a need for a controller that ensures an efficient power sharing among the MT-HVDC terminals, prevents the possibility of overloading, and utilizes the available power sharing. A new adaptive wireless control for active power sharing among multiterminal (MT-HVDC) systems, including power availability and power management policy, is proposed in this paper. The proposed control strategy solves these issues and, this proposed controller strategy is a generic method that can be applied for unlimited number of converter stations. The rational of this proposed controller is to increase the system reliability by avoiding the necessity of fast communication links. The test system in this paper consists of four converter stations based on three phase-two AC voltage levels. The proposed control strategy for a multiterminal HVDC system is conducted in the power systems computer aided design/electromagnetic transient design and control (PSCAD/EMTDC) simulation environment. The simulation results significantly show the flexibility and usefulness of the proposed power sharing control provided by the new adaptive wireless method.
This paper highlights some serious operating issues and challenges that are related to a parallel interlinking converters (ICs) interfacing an AC and a DC sub-grids of a hybrid AC/DC microgrid. These issue have not been investigated yet, especially in a hybrid AC/DC microgrid application. The first issue is the nonlinear load behavior of an IC during power exchange from AC to DC subgrid; which makes the IC acting like a harmonic voltage source that degrades the AC voltage and current. This behavior of the IC raises the second operation issue which is the circulating current that might exist in parallel ICs configuration. Seamless reconnection of an IC following abnormal operating conditions or schedule maintenance and the challenges associated with IC resynchronization are also examined. The paper also addresses in details the stability analysis, resynchronization issue and its effect on system stability. The theoretical expectations are verified by digital simulation using PSCAD/EM TDC simulation package.
This paper presents an optimal power flow (OPF) analysis of a multi-terminal high-voltage direct current (HVDC) system. The objective of the OPF analysis in this paper is to minimize not only the losses in the lines and the converters but also the generation cost by using a multi-objective function, which makes the system economically efficient. The constraints of voltages, both of the DC and AC power flows, and the line flows are the parameters that affect the optimization process. The proposed methodology covers both the AC and DC sides of the grid in terms of the lines as well as the DC/DC and AC/DC converter losses. In order to achieve a global optimal solution of the OPF problem, semidefinite programming (SDP) is used. SDP has been tested on an 8-bus system with one DC/DC converter and five AC/DC converters. The result of the optimization process is obtained and a comparison is made between neglecting and including the losses of the AC/DC and DC/DC converters.
Open Vehicle Grid Integration Platform (OVGIP) provides a unified interface using communication protocols where all the components of the VGI ecosystem can interact for managed EV charging. VGI allows two-way communication between the EVs and electricity grid to benefit EV owners and utility providers. However, VGI is a scale-based approach. It requires many EVs aggregated into the power grid to provide benefits of peak load management, smoothening of load curve, and balancing power supply and demand. The major challenge in India for commercial deployment of the VGI platform is insufficient charging infrastructure. In the present scenario, there are many obstacles in the path of OVGIP as it requires additional hardware, security and database management tools as well as modifications in the power supply systems, which is highly cost demanding. Moreover, EV charging is highly uneven, dynamic and unpredictable on the grid load, which causes inconveniences in the large-scale deployment of EVs. This paper emphasizes the importance of smart grid regulations, dynamic charging and demand response strategies explicitly designed for EV charging in India. Furthermore, this paper presents a comprehensive analysis of OVGIP for managed charging of EVs using proper communication and energy flow between the energy market, VGI platform and end-user interface. Lastly, the feasibility of OVGIP in the Indian scenario is thoroughly discussed and analyzed, addressing the technological, economic and electric power grid constraints.
The primary goal of a power distribution system is to provide nominal voltages and power with minimal losses to meet consumer demands under various load conditions. In the distribution system, power loss and voltage uncertainty are the common challenges. However, these issues can be resolved by integrating distributed generation (DG) units into the distribution network, which improves the overall power quality of the network. If a DG unit with an appropriate size is not inserted at the appropriate location, it might have an adverse impact on the power system’s operation. Due to the arbitrary incorporation of DG units, some issues occur such as more fluctuations in voltage, power losses, and instability, which have been observed in power distribution networks (DNs). To address these problems, it is essential to optimize the placement and sizing of DG units to balance voltage variations, reduce power losses, and improve stability. An efficient and reliable strategy is always required for this purpose. Ensuring more stable, safer, and dependable power system operation requires careful examination of the optimal size and location of DG units when integrated into the network. As a result, DG should be integrated with power networks in the most efficient way possible to enhance power dependability, quality, and performance by reducing power losses and improving the voltage profile. In order to improve the performance of the distribution system by using optimal DG integration, there are several optimization techniques to take into consideration. Computational-intelligence-based optimization is one of the best options for finding the optimal solution. In this research work, a computational intelligence approach is proposed to find the appropriate sizes and optimal placements of newly introduced different types of DGs into a network with an optimized multi-objective framework. This framework prioritizes stability, minimizes power losses, and improves voltage profiles. This proposed method is simple, robust, and efficient, and converges faster than conventional techniques, making it a powerful tool of inspiration for efficient optimization. In order to check the validity of the proposed technique standard IEEE 14-bus and 30-bus benchmark test systems are considered, and the performance and feasibility of the proposed framework are analyzed and tested on them. Detailed simulations have been performed in “MATLAB”, and the results show that the proposed method enhances the performance of the power system more efficiently as compared to conventional methods.
Multilevel inverters (MLIs) are a key solution for converting DC to AC power. In this article, an improved single-source SC-MLI topology is developed for solar PV applications. It consists of 12 unidirectional switches, 3 capacitors, and 3 diodes to provide sextuple voltage boosting with a lower cost function. Since the capacitor's voltage is self-balanced, there is no need for an additional circuit or sensors, bringing down the circuit's complexity. A simple and fundamental frequency-based control strategy, nearest-level pulse width modulation, is applied to assess the viability of the proposed topology. As a result, the proposed topology has an efficiency of over 97%, and it can generate 13 levels with a total harmonic distortion (THD) of 6.51%. Comparative analysis is performed to show the feasibility of the proposed topology which outperformed other 13-level similar topologies in terms of component count, cost factor, and boosting factor. The proposed topology's performance is evaluated under static and dynamic loads. Furthermore, the thermal analysis is performed using PLECS software to determine the efficiency of the circuit topology. Finally, the feasibility of the proposed circuit is verified for solar PV application.
The high potentiality for graphene to be used in nanotechnology may lead to an augmentation of the band gap issue due to the fact that the single layer of graphene officially has a zero band gap. Therefore, the concept of bilayer and trilayer is introduced to achieve a tunable band gap by applying an external electrical field. Considering that there is a limit to increasing the band gap by using the external electrical field, this paper presents a novel method that will increase the band gap based on Hummer's fabrication method. The simulation results show a significant outcome in the band gap tuning. The tests in this paper were simulated in a MATLAB environment.
This research paper proposes a novel generic synchronization method for microgrids that addresses the key limitations of existing approaches. The method enables seamless synchronization and reconnection across multiple microgrid operating scenarios without relying on communication infrastructure or phase-locked loops (PLLs). It can synchronize islanded microgrids with grid-connected systems, interconnect multiple islanded microgrids, and facilitate smooth transitions between operating modes. Notably, the approach maintains system stability and works effectively under both balanced and unbalanced conditions, including short circuits. The proposed technique is implemented at circuit breaker terminals and requires no modifications to the underlying converter control loops. This preserves system stability while enabling plug-and-play capability. The method also provides inherent protection features, automatically disconnecting during faults and re-synchronizing after fault clearance. Comprehensive simulations in PSCAD/EMTDC validate the approach across multiple test systems and operating scenarios. Results demonstrate the method’s effectiveness for synchronization, re-synchronization, and seamless mode transitions in various microgrid configurations including synchronizing multipoles microgrids with the IEEE 14-bus benchmark. The proposed generic synchronization technique represents a significant advancement in microgrid control, enhancing reliability and resiliency without compromising stability or requiring complex communication systems.
This paper presents an adaptive wireless droop control scheme that uses an adaptive virtual resistance to regulate the DC voltage and control the active power. The proposed methodology is implemented to address the power mismatch problem in a fixed-droop control for multi-terminal HVDC (MT-HVDC or MTDC) systems. Each inverter calculates available power and adjusts its output power accordingly while adapting the virtual resistance to mimic the behavior of a mesh system that is based on loading effects. The main objective of this methodology is to increase the reliability of the MTDC system by eliminating the need for fast communication links and ensuring proper power sharing between inverters. Additionally, this communication-free scheme includes a power management algorithm that controls power sharing during peak hours of the inverters among the rectifiers as per mutual agreements between the operators to mitigate the risk of a system overload and optimize the power sharing. A simulation of a five-terminal mesh MTDC system has been verified by using PSCAD/EMTDC to validate the performance and effectiveness of the proposed method. The results show the flexibility and feasibility of the proposed control method in three different modes.
