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The increase in penetration levels of inverter-based resources (IBRs) is changing the dynamic performance of power grids of different parts of the world. IBRs are now being more and more integrated into the grid at a single connection point as an IBR plant. Due to the complex nature and dynamicity of each inverter model, it is not realistic to build and analyze full complex models of each inverter in the IBR plant. Moreover, simulating a large plant including detailed models of all the IBRs would require high computing resources as well as a long simulation time. This has been the main issue addressed in the new IEEE Std 2800-2022. This paper proposes a novel approach to model an IBR plant, which can capture the transient nature at the plant level, detailed IBR control at the inverter level, interactions of multiple IBR groups in a plant structure, and a collector system connecting the IBRs to the grid. The IBRs in the plant use a voltage source inverter topology combined with a grid-connected filter. The control structure of the IBR includes a cascaded loop control where an inner current control and outer power control are designed in the dq-reference frame, and a closed-loop phase-locked loop is used for the grid synchronization. The mathematical study is conducted first to develop aggregated plant models considering different operating scenarios of active IBRs in an IBR plant. Then, an electromagnetic transient simulation (EMT) model of the plant is developed to investigate the plant's dynamic performance under different operating scenarios. The performance of the aggregated plant model is compared with that of a detailed plant model to prove the effectiveness of the proposed strategy. The results show that the aggregated EMT simulation model provides almost the same result as the detailed model from the plant perspective while the running time/computation burden is much lower. [ABSTRACT FROM AUTHOR]

Nowadays, a large number of inverter-based resources (IBRs) are integrated into the grid at a single connection point as an IBR plant. In this article, a virtual dynamic grid impedance concept is introduced to evaluate the harmonics and stability for grid integration of an IBR plant containing multiple IBRs. First, a detailed theoretical study is conducted to build a foundation of the virtual grid impedance concept, which is a dynamic impedance that changes with the number of IBRs added into an IBR plant. Then, based on the new virtual dynamic grid impedance concept, frequency spectrum analysis is performed to explore harmonic impact at the interconnection point for an IBR plant with IBRs having L, LC, and LCL filters, respectively. An electromagnetic transient (EMT) simulation model of a grid-connected IBR plant is developed to explore the harmonics and stability of the IBR plant connected to the grid as well as the reliable operation of IBRs within the plant from the novel virtual equivalent dynamic grid impedance point of view. Hardware experiments are conducted to validate the EMT simulation evaluation. The results show that the number of IBRs added into an IBR plant influences the grid impedance, i.e., grid strength, and the grid impedance variation has multiple impacts on the IBR plant and IBRs within the plant depending on the grid-connected filters of the IBRs. [ABSTRACT FROM AUTHOR]

Electric vehicle grid integration (EVGI) is one of the most important parts of transportation electrification. However, large-scale EV charging/discharging can have an adverse effect on the distribution grid, due to a large amount of load being drawn from or fed back to the power grid. Additionally, the power electronics used in the grid interaction may impose additional complications, such as voltage and frequency deviation, harmonic distortion, etc. With proper control scheme designs for the grid-connected inverters, such complications can be mitigated, and several grid ancillary services, such as voltage and frequency support, reactive power support, and harmonic mitigation, can be facilitated from large-scale EVGI. In this study, a large-scale EVGI system is developed where the vector control implementation of a grid-connected inverter in the d-q reference frame is presented for providing different grid ancillary services using the EVGI system. The EVGI system is operated in different control modes to ensure multiple ancillary services of the power grid. The study is supported by the electromagnetic transient simulation performed in Matlab/Simulink of a large-scale EVGI system. The simulation shows that with the proper control mechanism of grid-connected inverters, EVGI can be used to provide several useful grid ancillary services. [ABSTRACT FROM AUTHOR]

Application of fuel cell (FC) in power generation requires efficient power converters and controllers for hybridization of energy storage devices. This paper presents the control technique in a fuel cell and ultracapacitor hybrid system to eliminate the slow dynamic problem of FC. The control technique involves a linear quadratic regulator and proportional integral (LQR–PI) controller, where the FC boost converter and the UC bidirectional converter are controlled using a double-loop PI controller and a voltage-mode LQR controller, respectively. The simulation with different types of load was performed to compare the performance of the proposed controller with both PI and LQR controllers. The results revealed that the LQR–PI controller had better overshoot and undershoot responses (7.37% and 6.43%, respectively) than the proportional integral controller (11.47% and 11.42%, respectively) and linear quadratic regulator (23.87% and 21.5%, respectively). The energy sharing performance was verified through variation in load resistance and disturbances in bus voltage. The voltage recovery time of LQR–PI controller was slightly higher (200 ms) than that of the LQR controller (23.8 ms) and, however, lower than that of the PI controller (300 ms). The results revealed that the proposed controller is efficient for load voltage as well as load current fluctuations. [ABSTRACT FROM AUTHOR]

Fuel cell (FC) application in vehicular technology has gained much popularity since the past few years. Typically, fuel Cell Hybrid Electric Vehicle (FCHEV) consists of fuel cell, battery and/or ultracapacitor (UC) as the power sources. The power converter is integrated to the power sources to form the hybrid FC system. This helps to compensate the drawback of individual power sources. Apart from the technical efficiency of power sources itself, the performance of an FCHEV is governed by the efficiency of power electronics and associated controller. In this paper, a state-of-the-art of vehicle classification is reviewed, in which the focus is placed on the deployment of fuel cell, battery, ultracapacitor and flywheel. The configurations used in FCHEV, followed by the updated power converter topologies, are also discussed. The topologies are categorized and discussed according to the power stages and control techniques used in the configurations. Then, multiple stages conversion and single stage topologies are described chronologically. The advantages and disadvantages of each topology, safety standards, current situation and environmental impact of FCHEV are also discussed. In addition, the current development of FCHEV, challenges and future prospects are also elaborated. The rapid growth of FC based research and technology has paved great prospects for FCHEVs in the near future, with the prediction of the competitive cost of hydrogen as compared to gasoline. [ABSTRACT FROM AUTHOR]

Costly and eco-destructive diesel based systems are usually used for electrifying rural areas in Malaysia. Fuel transportation is another obstacle in this regard. Moreover, unpredictable fluctuation of fuel price makes the system cost unstable. The diesel based systems can be replaced with renewable energy (RE) based systems. Thus, a feasibility analysis is necessary to assess the potentiality of RE resources. This paper analyzes the potentiality of renewable energy in Sarawak, East Malaysia. The wind speed is insufficient, but solar energy is abundant at the location. Hence, the feasibility of photovoltaic (PV), Battery and Fuel Cell (FC) based systems are investigated for the load of a village longhouse comprising 50 families located in Kapit, Sarawak. Both systems, including FC (PV/Battery/FC) and excluding FC (PV/Battery) are analyzed and compared with conventional diesel based system. The analysis focuses on net present cost (NPC) and cost of energy (COE). Other cost parameters such as installation cost, operation and maintenance cost (O&M), operating cost are also analyzed. HOMER software provided by National Renewable Energy Laboratory (NERL) is used as an analyzing tool. This paper also focuses on the operational strategy and sensitivity analysis of the hybrid system for optimal performance. The HOMER optimization results and sensitivity analysis show that the PV/Battery system is economical and environmentally friendly with total net present cost of $ 335,297 and cost of energy of 0.323 $/kWh with no emission. Thus it can be a suitable replacement of diesel based system. The FC based system has higher costs; thus despite of its benefits, it is not suggested as the best system for the situation. [ABSTRACT FROM AUTHOR]

Due to the depletion of fossil fuel reserves, it is feared that the world will run out of its energy resources soon. Besides, unpredictable fluctuation of diesel prices in electricity generation is affecting the economy of a country. Thus, for developing country that's economically leans on the use of energy, renewable energy resources should be utilized to meet the increasing energy demand. In this regards, the cogeneration system using renewable energy sources is appropriate, because it has the advantage of producing both electrical power and heat energy from a single fuel. It is suitable for commercial clients like hospital buildings which requires to supply both electric and heat load. Therefore, the aim of this study is to assess the viability to develop a cogeneration system for a hospital building load in Malaysia. The proposed cogeneration system consists of grid connected photovoltaic (PV), fuel cell, and battery. Hybrid optimization model for electric renewable (HOMER) simulation software is used to perform the techno-economic analysis of the proposed system. The proposed system is then compared with other possible configurations. The economical comparison is based on the total net present cost (TNPC), levelized cost of energy (LCOE), renewable fraction, excess energy production and the pollutant gas emission of the system. The simulation result shows that, the proposed cogeneration system has the lowest TNPC, LCOE and operating cost which are $ 106,551, 0.091 $/kWh and 7245 $/yr respectively. Besides, the proposed cogeneration system is proven environmentally friendly as it only produces total 25,873 kg/yr of pollutant gas. The sensitivity analysis where fuel prices and annual interest rate are considered as sensitive parameters, shows impact on the TNPC and LCOE. Finally, the benefit from the Feed in Tariff (FiT) program provided by the government also has been presented. [ABSTRACT FROM AUTHOR]

Bangladesh being a developing country is struggling for the self-sufficiency of electric power for a very long time. In this run renewable energy can play an important role for electricity generation. Bangladesh abuts by Bay of Bengal, as a result the southern areas face around 2∼5 m of tidal head/height rise and fall and as it is in the tropical region it gets an average daylight of 7∼8 hper day. Thus the hydro (tidal) energy and solar energy can be the key points to meet the scarcity of power. This paper discusses a model of possible small hybrid power generation system consisting of a PV generation unit with storage and a micro-hydro generation unit and a diesel generator which can mitigate the rising energy demand at the southern areas of Bangladesh. In this paper the economic viability is discussed along with the technical aspects to set up such system via HOMER analysis. Moreover the system cost was analyzed together with a comparison of other system costs of similar capacity. [ABSTRACT FROM AUTHOR]

With the proliferation of large-scale grid-connected wind farms, subsynchronous oscillation (SSO) incidents associated with Type-4 wind turbines (WTs) with a permanent magnet synchronous generator (PMSG) have occurred frequently. These incidents have caused severe reliability risks to the power grid. Conventionally, P-Q capability charts are utilized to ensure the safety operating region of a synchronous generator. However, a PMSG WT exhibits completely different and dynamic P-Q capability characteristics due to the difference in energy conversion technique and several critical factors related to the WT power converters. This paper presents a comprehensive dynamic P-Q capability study of a PMSG WT with sufficient and accurate considerations of the WT control and operation in the dq reference frame, its power converter constraints, and grid dynamics. Models of a PMSG WT are first developed based on its control principle in the dq reference frame. Then, algorithms for obtaining the P-Q capability charts of the WT are developed with the considerations of complete WT constraints in different aspects. The study analyzes the root cause of many abnormal operations of grid-connected PMSG WTs, reported in the literature, from the dynamic P-Q capability perspectives. The proposed study is verified via an electromagnetic transient (EMT) model of a grid-connected Type-4 WT. [ABSTRACT FROM AUTHOR]

• Vehicle-to-Grid (V2G) framework permits bi-directional power flow from a vehicle's battery to the power grid. • A deterministic and a probabilistic method of PHEV charging/discharging schedule are analyzed and their performances are compared based on a case study at Riyadh city, Saudi Arabia. • On the deterministic method, an optimization model is proposed to reduce overall grid power consumption for utilities and operate smart charging and discharging schedule for PHEV users. • The probabilistic method uses Monte Carlo Simulation (MCS) to analyze the impact and determine a coordinated Time of Unit (TOU) type for PHEV charging/ discharging schedule. Within the next decade, the number of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) will increase exponentially owing to the environmental benefits related to their utilization. In an ideal framework condition, the vehicle-to-grid (V2G) system provides advantages such as subordinate administration of load leveling and peak shaving guidelines, and minimized upgrade costs. In this paper, deterministic and probabilistic methods of scheduling PHEV charging/discharging are analyzed, and their performances are compared based on a case study. In the case of the deterministic method, an optimization model is proposed to reduce the overall grid output power consumption for utilities and operate a smart charging/discharging schedule for PHEV users. Quadratic programming (QP) is used to solve the optimization cost function. In contrast, the probabilistic method uses Monte Carlo simulation (MCS) to analyze the impact and determine a coordinated time-of-use (TOU) structure for the PHEV charging/discharging schedule. Both methods suggest V2G feasibility for the smart grid system. [ABSTRACT FROM AUTHOR]

Due to the rapid development in modern power industrial applications such as renewable energy, photovoltaic, laptop adapters and electric vehicles, DC/DC resonant converters have gained the attention of many researchers. The rise of the potential of this industry has since led to a plethora of studies on resonant converter topologies with the aim to enhance the features of soft switching, high power density, smooth waveforms and high efficiency. The efficiency of these converters has been proven, thus are undoubtedly favored over hard switching conventional converters because of their ability to both work at high frequency and reduce switching losses. Researches are still being continued to significantly reduce the cost and number of components, besides improving areas such as high power density, high efficiency, wide load variations, and reliability. This paper presents the principles of resonant power converters (RPCs) and their classifications based on their DC-DC converter family, and ability to achieve soft switching. Several recent research trends have focused on the development of their constructions, operational principles, merits and demerits. The study of different resonant DC–DC converter topologies suggests that there is no single topology which can achieve all requirements. Therefore, further research is required to produce a power circuit that can eliminate the addressed limitations as many as possible. [ABSTRACT FROM AUTHOR]

• NTSMC-based cascaded control for a DC/DC converter to increase the robustness. • A VIC method to increase the inertia of the DC/DC converter-interfaced DG unit. • Synchronization control to satisfy the plug-and-play of a buck-boost converter. • Hardware experimental results demonstrate the improved performance. To deal with the issues caused by the high integration of renewable resources, the parallel operation of the converters is generally required to improve the system stability and reliability. To support the parallel operation of buck-boost DC/DC converters, they are generally regulated by a cascaded control strategy, which includes droop control loop, and nested proportional-integral (PI) based voltage and current control loops. However, it can provide barely inertia support and needs precise system model to reach the desired performance. In order to overcome these drawbacks, this paper proposes a novel cascaded control strategy for parallel operation of buck-boost DC/DC converters. The proposed cascaded control strategy involves a voltage synchronization loop, a virtual inertia control (VIC) loop, and two nested NTSMC based voltage and current control loops. The voltage synchronization controller can enable the plug and play requirements by synchronizing the output voltage of the converter with the voltage at the point of common coupling (PCC) before connecting a DC/DC converter to the DC microgrid. The VIC can improve the inertia of the converter-interfaced DGs. The nested-loop NTSMC based voltage and current controller can improve the robustness of converter system. Hardware experiments demonstrate the improved performance of the proposed control strategy. [ABSTRACT FROM AUTHOR]