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This paper proposes a new transformerless buck‐boost converter with an extended voltage conversion ratio. This converter has semi‐quadratic voltage gain, which provides more gain with lower duty cycles. This converter has a simple structure and easy implementation, which reduces the cost and increases efficiency. The proposed converter operates in continuous conduction mode and provides two operation modes by turning on and off the switches. The suggested converter has continuous input current and low input current ripple, which is important when utilizing renewable energy sources. The calculation of the proposed converter includes ideal and practical voltage gain, current calculations, voltage stresses of the switches and diodes, current stress of the switches, parameter design, efficiency, and a brief analysis of discontinuous conduction mode and boundary conditions. The proposed converter provides efficiency of about 93.1% in boost mode and 92.14% in buck mode at 50 W output power. The suggested converter varies the input voltage from 20 to 48 V in boost mode and changes the input voltage from 20 to 10.4 V in buck mode. Finally, a laboratory prototype has been built to prove and evaluate the simulation results and theoretical analysis of the proposed converter. [ABSTRACT FROM AUTHOR]

In this study, to solve total harmonic distortion (THD) and voltage stress on switches, challenges have been made by presenting a new multi‐level inverter (MLI). The proposed topology can operate with both symmetric and asymmetric sources. The proposed topology in symmetric and asymmetric mode with 18 switches can produce 17 and 49 voltage levels, respectively, with THD values of 4.14% and 1.45%, which passes the IEEE harmonic standard. The main advantage of the proposed topology is reducing the number of circuit devices, which reduces the price, volume, and complexity of the circuit by reducing the number of circuit devices. The proposed topology reduces the THD, the number of power electronics components, and voltage stress by increasing the output levels. The proposed topology is compared with other topologies and the advantage of the proposed topology is shown in terms of the number of switches and drivers. In addition, the proposed topology is compared in terms of the cost function. The power losses based on the thermal model of the proposed topology have been analysed and simulated. Simulation and experimental results are presented for different scenarios such as load type, load changes, and modulation index changes to validate the proposed topology. [ABSTRACT FROM AUTHOR]

Today, multilevel inverters are widely utilized in various applications. Reducing the number of components in the design of these converters is one of the crucial goals so that they have less volume and cost. This paper presents a single‐source structure for a multilevel switched‐capacitor inverter with voltage boost capability. The proposed structure can generate 25 sinusoidal‐like step voltage levels with a six times amplitude increase compared to the input. This converter uses only one direct current (DC) power source, 14 switches, and four capacitors. The nearest level control switching method has been used to control the converter, create voltage levels, and select the switching modes. A comprehensive comparison has been made with other recently presented structures to demonstrate the efficiency of the proposed structure. The advantages of the proposed structure include using only one DC voltage source, the ability to increase the output voltage six times compared to the input, the use of fewer power electronics components compared to the number of voltage levels, proper efficiency, self‐balancing of capacitors, and as a result, the lower cost. The performance accuracy of the proposed converter has been simulated in the MATLAB Simulink environment and then evaluated by a laboratory prototype. [ABSTRACT FROM AUTHOR]

Summary Multilevel inverters are known as essential converters in renewable sources. First, in this paper, a new submodule is presented, and based on it, a new sub‐multilevel inverter is presented. The proposed sub‐multilevel inverter consists of several unidirectional and bidirectional switches and DC voltage sources. Then, the generalized topology, developed in two modular and cascaded modes, is presented to increase production levels. The proposed submodules are connected in series in the modular topology, increasing production levels. The proposed topology to produce the maximum output levels has the minimum number of IGBTs, drivers, DC voltage sources, etc. Mathematical analyses for conduction and switching losses are provided, and mathematical analyses for the number of devices and voltage across the switches are also presented. In addition to the mathematical analysis of losses, the simulation results are also presented. A general comparison of proposed topology components is presented to demonstrate their advantages. This comparison shows that the proposed topology has the minimum number of power electronic devices. In this paper, nearest level modulation is used to control the proposed topology. The simulation and experimental results of the proposed sub‐multilevel verify the performance of the proposed topology. [ABSTRACT FROM AUTHOR]

This paper presents a non‐isolated single‐switch ultra‐high step‐up (UHSU) DC–DC converter with a three‐winding coupled inductor (CI) which is utilized to achieve ultra‐high voltage gain with a small amount of duty cycle leading to low conduction losses of the power switch and higher efficiency. The voltage gain of the suggested UHSU converter is adjusted by two methods: the duty cycle of the power switch and the three‐winding CI turn ratio, therefore enhancing the design flexibility of the suggested converter. Due to the utilization of the passive clamp circuit in the structure of the proposed converter, it is possible to select a power switch with low voltage rated and small ON‐state resistance, further enhancing the converter efficiency. The operation modes are discussed in detail and to clarify the salient features of the proposed converter, a comparison with other configurations is provided. Finally, to accredit the performance of the proposed converter, a 150‐W laboratory archetype with an input and output voltage of 20 and 300 V, respectively, at 50 kHz switching frequency is fabricated. [ABSTRACT FROM AUTHOR]

The optimal operation of power systems is one of the most critical issues for operators. Optimizing the operation of power systems while accommodating the increasing penetration of RES, owing to the intermittent and variable nature of these resources, stands as one of the most critical challenges for power systems. Numerous primary challenges, including fluctuations in load and nonlinear constraints, further complicate the issue, given its substantial dimensions. Therefore, this paper introduces an approach for improving the management of optimal generation and the associated carbon emissions costs of traditional power plants, which is achieved through integrating wind farms and incorporating battery energy storage. This enhancement is achieved by integrating wind farms and utilizing battery storage systems while considering the costs associated with traditional units using fossil fuels and the expenses related to carbon emissions. The simulation incorporates seven load customer types and five traditional generation sources integrated with wind farms and battery storage devices. The simulation results demonstrate that the new problem formulation has significantly improved the ability and performance of optimizing the scheduling of power plant generations. [ABSTRACT FROM AUTHOR]

Summary: Multilevel inverters have many applications, such as the grid integration of photovoltaic cells, FACTSs devices, electric vehicles, variable speed drives, and smart grids. In this paper, a new bidirectional diode‐based unit is proposed for a symmetric single‐phase modular inverter topology that can achieve high output levels by using a small number of switching and circuit devices. The basic structure can generate nine‐level voltage with only nine IGBTs and two diodes. Another advantage of the proposed topology is the utilization of a half‐bridge module to change the voltage polarity and the low number of its voltage sources. Additionally, the proposed topology can be used as the cascaded structure with different approaches to select the value of voltage sources. The power losses are discussed for the proposed basic module. A comparison has been made with some recently presented topologies to compare the proposed multilevel inverter and demonstrate its superiority. The comparison is performed for the basic module and its generalized structure. In this paper, the pulse width modulation technique is utilized to achieve a voltage waveform with low harmonic content. The proposed basic structure has an efficiency of 58.98% in 5KW power. Finally, the operation of the proposed basic module is simulated, and the laboratory prototype results confirm the accuracy of the simulation results. [ABSTRACT FROM AUTHOR]

In this paper, a new transformerless buck–boost converter is proposed. This converter is based on combining two basic converters, including Cuk and traditional buck–boost converters, along with a voltage multiplier (VM) at the output side. The proposed semi‐quadratic buck–boost converter operates in continuous conduction mode (CCM) and provides two operation modes by turning the switches on and off. This converter has some merits such as a wide conversion ratio and continuous input current. The proposed converter consists of two switches with simultaneous operation resulting in simplicity in control. A modular configuration and a wide range of duty cycles are available through the proposed converter, which causes higher or lower output voltage and facilitates the converter maintenance. The calculations of the ideal and the real voltage gain, voltage stress of switches and diodes, efficiency, and design consideration of elements are given in this paper. Finally, a prototype is implemented, and experimental waveforms are obtained to prove and validate the simulation results as well as the theoretical analysis of the proposed converter. [ABSTRACT FROM AUTHOR]

Multi‐level inverters (MLIs) for medium or high power and voltage utilization have acceptable application in industry and are utilized commercially. The performance of MLIs is considerably preferable to traditional two‐level inverters due to their negligible harmonic content, small filter size, utilization of lower‐rated voltage devices, low electromagnetic interference (EMI), and so on. However, in the face of these many advantages, few disadvantages can be expressed such as more device count and a sophisticated control strategy. This paper presents an improved switched‐ladder topology to enhance the performance of multi‐level inverters by improving the above drawbacks. Compared to existing inverter topologies, the proposed extendable diode‐containing bidirectional structure requires fewer switches and driver circuits. The proposed topology is compared with other similar topologies, and its superiority is examined. Fundamental switching frequency modulation technique is utilized to obtain high‐quality output voltage waveforms with lower harmonic contents and reduced switching losses. This converter, despite the use of diodes, can supply the low power factor inductive‐resistive loads, bidirectionally. To demonstrate the performance of the proposed topology, in addition to simulation with the nearest level modulation technique, a prototype of the proposed structure has been implemented and tested. The results display the proper performance of the proposed topology in the real‐time environment. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a bidirectional diode containing multilevel inverter is introduced to reduce the number of switching elements especially in the case of a high number of output voltage levels. In comparison with classic and recently introduced symmetrical topologies, which are trying to reduce the switch count, this topology has a lower number of semiconductor switches in the same number of output voltage levels. This makes the proposed inverter to be a suitable choice for medium voltage applications like renewable energy applications as well as medium voltage electric drives. Moreover, it can be used in a cascaded configuration for high voltage levels. To depict the performance of the proposed structure, a comprehensive comparison is made between this topology and classic and recently proposed symmetric topologies in terms of switch and gate driver count, power losses, and cost. The performance of the proposed symmetrical 11‐level converter is analyzed and simulated in MATLAB/Simulink for both PWM and selective harmonic elimination switching methods. Not only the results are desirable but also the experimental results of laboratory prototype validate the simulation results. [ABSTRACT FROM AUTHOR]

Inverters as one of the most important elements of power systems have been profoundly developed in recent decades and their performance has attracted researches in control and structure point of view. In this study, a novel structure based on the switch-diode-source cell is proposed for a multilevel converter that is capable of bidirectional feeding. The proposed structure is presented for symmetrical mode and the number of power electronic devices is decreased in comparison with similar works. Considering recent proposed symmetrical structures, the proposed structure has the superior condition in terms of semiconductor switches and drivers count as well as switching loss. Also, total blocked voltage (TBV) of the proposed converter is compared with conventional and novel symmetrical converters. Then, switch costs of the proposed converter are compared with the structure that its TBV is the lowest. The performance of the proposed symmetrical seven-level converter is analysed and simulated in MATLAB/Simulink for both PWM and selective harmonic elimination switching methods. Not only the results are desirable, but also the experimental results of laboratory prototype validate the simulation results. [ABSTRACT FROM AUTHOR]

Development in utilising the energy storage system (ESS) has led to increasing flexibility in the planning of energy networks. This study presents optimal day-ahead scheduling for multi-carrier energy networks in the presence of ESS. To achieve this purpose, a new economic approach for ESS is proposed that aims to utilise for generation management in the multi-carrier networks. Also, the proposed economic approach presents a novel pricing policy that reduces the total cost of the system at each time interval. Therefore, the proposed pricing policy results in obtaining the charging and discharging pattern of ESS adaptively. To solve the multi-period optimal energy flow problem in multi-carrier energy networks, this study utilises the well-known teaching-learning based optimisation algorithm. The investigated multi-carrier energy system consists of electrical, natural gas and district heating sub-networks in which an ESS is included in the electrical sub-network. The performance of the proposed approach is validated by comparing the ESS daily charging and discharging pattern and the daily load demand curve. The results show that the proposed method could be utilised for load shedding and tracking the load demand curve more effectively. [ABSTRACT FROM AUTHOR]

With the increasing trend in the integration and deployment of distributed energy resources, the real-time assessment of power system transient stability is becoming more and more challenging. This study presents an enhanced sensitivity-based decentralised transient stability assessment scheme, which first virtually decomposes the large-scale power network into several smaller areas. Then, a new sensitivity-based scheme is developed to derive and quantify the kinetic energy-based stability assessment index. This index allows taking into account the effects of both AC generators and power electronic-based generator units. In addition, thanks to the new sensitivity-based scheme, the transient stability can be assessed in a decentralised manner using only the boundary buses in each segmented area, which relaxes the need for massive data availability and transfer across the network and enables its applicability for online applications in large-scale power systems. Simulation results on the 48-machine IEEE 140-bus and 544-machine 2000-bus synthetic power grid test systems demonstrate the efficacy of the proposed method. [ABSTRACT FROM AUTHOR]

Development in utilising the energy storage system (ESS) has led to increasing flexibility in the planning of energy networks. This study presents optimal day‐ahead scheduling for multi‐carrier energy networks in the presence of ESS. To achieve this purpose, a new economic approach for ESS is proposed that aims to utilise for generation management in the multi‐carrier networks. Also, the proposed economic approach presents a novel pricing policy that reduces the total cost of the system at each time interval. Therefore, the proposed pricing policy results in obtaining the charging and discharging pattern of ESS adaptively. To solve the multi‐period optimal energy flow problem in multi‐carrier energy networks, this study utilises the well‐known teaching‐learning based optimisation algorithm. The investigated multi‐carrier energy system consists of electrical, natural gas and district heating sub‐networks in which an ESS is included in the electrical sub‐network. The performance of the proposed approach is validated by comparing the ESS daily charging and discharging pattern and the daily load demand curve. The results show that the proposed method could be utilised for load shedding and tracking the load demand curve more effectively. [ABSTRACT FROM AUTHOR]

With the increasing trend in the integration and deployment of distributed energy resources, the real‐time assessment of power system transient stability is becoming more and more challenging. This study presents an enhanced sensitivity‐based decentralised transient stability assessment scheme, which first virtually decomposes the large‐scale power network into several smaller areas. Then, a new sensitivity‐based scheme is developed to derive and quantify the kinetic energy‐based stability assessment index. This index allows taking into account the effects of both AC generators and power electronic‐based generator units. In addition, thanks to the new sensitivity‐based scheme, the transient stability can be assessed in a decentralised manner using only the boundary buses in each segmented area, which relaxes the need for massive data availability and transfer across the network and enables its applicability for online applications in large‐scale power systems. Simulation results on the 48‐machine IEEE 140‐bus and 544‐machine 2000‐bus synthetic power grid test systems demonstrate the efficacy of the proposed method. [ABSTRACT FROM AUTHOR]

In this study, the holomorphic-embedding method as a linear and non-iterative method is developed and implemented to solve the load flow of the three-phase unbalanced radial distribution networks. Previously, this method was used to solve the load flow problem of balanced transmission networks. The proposed methodology could be applied for a variety of unbalanced radial distribution networks with any number of buses and branches. The characteristics of unbalanced radial distribution networks including line coupling effects, unbalanced loads and unsymmetrical phases are considered in this study. The proposed method uses an unbalanced network structure and modifies the calculation approach of the admittance matrix. In this manner, an unbalanced network is modelled the same as the balanced networks. The tap-changer, doubly-fed induction generator (DFIG), and photovoltaic system are modelled in the admittance matrix or current injection vector. The performance of the proposed method is validated on the 19-bus unbalanced radial distribution network. Finally, the effectiveness of the proposed method in solving the load flow problem is investigated. [ABSTRACT FROM AUTHOR]

In this study, the holomorphic‐embedding method as a linear and non‐iterative method is developed and implemented to solve the load flow of the three‐phase unbalanced radial distribution networks. Previously, this method was used to solve the load flow problem of balanced transmission networks. The proposed methodology could be applied for a variety of unbalanced radial distribution networks with any number of buses and branches. The characteristics of unbalanced radial distribution networks including line coupling effects, unbalanced loads and unsymmetrical phases are considered in this study. The proposed method uses an unbalanced network structure and modifies the calculation approach of the admittance matrix. In this manner, an unbalanced network is modelled the same as the balanced networks. The tap‐changer, doubly‐fed induction generator (DFIG), and photovoltaic system are modelled in the admittance matrix or current injection vector. The performance of the proposed method is validated on the 19‐bus unbalanced radial distribution network. Finally, the effectiveness of the proposed method in solving the load flow problem is investigated. [ABSTRACT FROM AUTHOR]

The measured fault voltage signal through coupling capacitor voltage transformer (CCVT) contains transient components which highly affect the estimated fundamental frequency phasor. This paper presents a new hybrid method which aims to calculate and remove the unwanted effect of CCVT transient on the fundamental phasor estimation. The main novelty of the proposed method is that proposed method is independent from the CCVT parameters involved in the transient response. In other words, unlike previously published papers, this method calculates the CCVT characteristics involved in the transient response. To such aim, by utilizing frequency modulation, fault voltage signal is shifted. Utilizing simple but comprehensive formulations based on integration and Prony‐complex theory, the CCVT characteristics are calculated in the first cycle after fault inception. After that, by utilizing modified discrete Fourier transform (MDFT), the fundamental phasor component is calculated in one cycle. Several simulated test signals are applied to the proposed method. The simulation results illustrate that the proposed method removes the unwanted effects of CCVT. Also, it is fast and has a good precision in estimating the fundamental phasor component of fault voltage signal under different simulation scenarios. [ABSTRACT FROM AUTHOR]

In addition to high‐order harmonic and noise components, the fault current may contain decaying DC components which highly affect the estimated fundamental frequency phasor. This study presents a new hybrid method which aims to calculate and remove the unwanted effect of decaying DC components on fundamental phasor estimation. The main novelty of the proposed method is that the proposed method is independent of the dynamic behaviour of the current transformer (CT). In other words, unlike previously published papers, this method analytically calculates the CT time constant. To such aim, utilising frequency modulation, fault current signal is shifted. Utilising simple but comprehensive formulations based on integration and Prony‐complex theory, the magnitude and time constant of decaying DC components are calculated in one cycle. After that, utilising a modified discrete Fourier transform the fundamental phasor component is calculated. Several test signals and also practical fault signals are applied to the proposed method. The simulation results illustrate the proposed method simply but comprehensively remove the unwanted effects of the decaying DC components. Also, it has quick speed as well as a high‐precision response in the estimation of fundamental phasor under different simulation scenarios. [ABSTRACT FROM AUTHOR]

In addition to high-order harmonic and noise components, the fault current may contain decaying DC components which highly affect the estimated fundamental frequency phasor. This study presents a new hybrid method which aims to calculate and remove the unwanted effect of decaying DC components on fundamental phasor estimation. The main novelty of the proposed method is that the proposed method is independent of the dynamic behaviour of the current transformer (CT). In other words, unlike previously published papers, this method analytically calculates the CT time constant. To such aim, utilising frequency modulation, fault current signal is shifted. Utilising simple but comprehensive formulations based on integration and Prony-complex theory, the magnitude and time constant of decaying DC components are calculated in one cycle. After that, utilising a modified discrete Fourier transform the fundamental phasor component is calculated. Several test signals and also practical fault signals are applied to the proposed method. The simulation results illustrate the proposed method simply but comprehensively remove the unwanted effects of the decaying DC components. Also, it has quick speed as well as a highprecision response in the estimation of fundamental phasor under different simulation scenarios. [ABSTRACT FROM AUTHOR]

This study presents a new powerful method for probability density function (PDF) estimation of the probabilistic power flow problem results. The proposed method works on a prior density function to improve its potential PDF estimation. The generalised cross-entropy method is used to refine the initial dataset. Most of the existing methods for PDF estimation do not provide a sparse result and rely on approximation and simplification. Compared to the other conventional methods, the proposed method has some remarkable features in density estimation. Low computational burden or high-speed response and high-precision results are the most prominent features of the proposed method. The method can deal with a correlated problem which is considered the correlation between uncertain parameters. It is tested on IEEE 14-bus and IEEE 118-bus systems, considering the non-stationary loads, some renewable energy resources and their correlations. The results of the proposed method are compared against more accurate results obtained from Monte Carlo simulation and some other conventional methods in density estimation. Comparisons confirm the high accuracy level and speed of the proposed density estimator against the other methods. [ABSTRACT FROM AUTHOR]

Expansion of cogeneration technologies, such as combined heat and power units, has boosted the growth of multi-carrier energy systems. A two-step method is presented to enable residential demand response (DR) programmes in the multi- carrier energy systems. In the first step, the energy management system at each home solves an optimisation problem to achieve the desired energy cost and demand schedule for the customer according to received price signals. In the second step, the system operator revises the demand scheduling by running another optimisation problem to minimise the total electrical losses, subject to the operational characteristics of electrical and natural gas systems. In order to persuade customers to participate in the DR programmes, it is guaranteed that the resulted cost of the second step is not more than the desired cost of the customer in the first step. Results of applying the proposed method, incorporating different penetration levels of customer participation in a time-of-use programme is studied in a test energy system. Simulation results verify the effectiveness of proposed method in minimising the total electrical losses, improving the operational characteristics of the energy system as well as providing customers' utilities. [ABSTRACT FROM AUTHOR]

Due to current transformer (CT) saturation, the secondary current waveform may contain distortions which results in mal‐operation of the protective system. This study presents a framework that attempts to detect and reconstruct saturated secondary current of the CT. To such aim, first an algorithm is proposed which detects and discriminates between normal and abnormal condition. This algorithm which is based on high‐order derivatives and statistical criterion, classifies load change, inrush current and fault condition. In addition, this algorithm is designed so that it detects the first time that CT becomes saturated. After fault detection and phase fault selection, based on analytical and comprehensive formulations, the parameter of fault current signal is calculated in the sub‐cycle. Moreover, the dynamic behaviour of the CT is considered in the waveform reconstruction. Several case studies are carried out to investigate the performance of the proposed method. Simulation results show that proposed method can effectively classify the inrush current and fault signal even in the CT saturation condition. Also, under different CT saturation condition, proposed method quickly and precisely detects and reconstructs saturated waveform without sacrificing details. [ABSTRACT FROM AUTHOR]

The growth of utilisation of wind turbines in the contemporary power systems, the transient stability (TS) evaluation has turned to a challenging issue in the modern power grids. An innovative and high‐precision real‐time method based on the transient energy function (TEF) is proposed which aims to evaluate the TS of power system in the presence of wind turbines. The proposed method is designed so that the initial point of TEF is calculated precisely by performing offline calculations. Structure preserving is used to guarantee the accuracy of the proposed method in order to consider the details of power system modelling. Moreover, the proposed method takes into account the impacts of the wind turbines controllers utilising new formulation based on a sensitivity‐based approach. The new formulation is utilised to calculate the effects of the controllers reflected in the potential terms of TEF during the fault occurrence. As a result, in addition of considering fault‐on trajectory, the latter technique causes reducing the computational burden and also guarantees accurate real‐time assessment of TS. The simulation results demonstrate the efficiency and also comprehensiveness of the proposed method in calculation of critical clearing time and TS assessment. [ABSTRACT FROM AUTHOR]

Summary: This paper describes the experimental results from flexural strengthening of old‐type concrete columns reinforced with plain bars and different lap splices constructed before the 1970s. Nine half‐scale column specimens were tested under combined constant axial and quasi‐static cyclic lateral loads. The specimens included 3 control specimens and 6 other specimens strengthened via near surface mounted technique with glass‐fiber reinforced plastic and steel bars. The effect of different longitudinal bar lap splices of columns and the type of strengthening materials were also investigated. The results indicated that the proposed strengthening method significantly increases the flexural strength and improves the seismic parameters, for example, energy dissipation and hysteresis damping. The specimens strengthened with steel bars presented higher strength, ductility, and hysteresis damping compared to those strengthened with glass‐fiber reinforced plastic bars. The formation of struts at the control specimen with hooked lap splices caused severe damages at the spliced region; if appropriate wrapping is done at the column end, these damages will be constrained. Using steel bars as near surface mounted reinforcement, utilizing epoxy resins as bonding agent, and installing fiber‐reinforced polymer wrapping at the end of column will all make a more effective strengthening method. Finally, an analytical work was presented for predicting the capacity of test specimens, and the comparison between experimental results and theoretical predictions showed a good agreement. [ABSTRACT FROM AUTHOR]

Decaying DC component has considerable effect on both accuracy and speed of convergence in numerical and digital relays for estimating fundamental phasor. Basically, this component causes unwanted and undesired oscillations in the time response of the fundamental phasor. As a result, it extremely affects decision making of the protective relay, which operates according to fundamental phasor component. In this study, a novel hybrid algorithm based on integration and half-cycle discrete Fourier transform (HDFT) is presented. Proposed method of this study is able to efficiently estimate fundamental frequency component by taking different parameters, including DC offset in the fault current, DC offset in a current transformer secondary side and off-nominal frequency condition into account. Moreover, in this study, modified DFT-based method for phasor estimation that is called combined integration and HDFT (CIHDFT) is put forward, which accurately estimates the original value of fundamental frequency phasor in half-cycle by considering the presence of harmonics in the waveforms. The proposed method is successfully applied to different test cases, followed by discussion on the results. Analysing the simulation results, it can be concluded that CIHDFT algorithm has remarkable performance in comparison with previous phasor estimation algorithms. [ABSTRACT FROM AUTHOR]

Simultaneous expansion of the electrical and thermal energies collected with conventional expansion options is scrutinised. A robust, bio‐inspired evolutionary optimisation method is proposed, to handle the complex expansion planning of a system consisting of both electrical and thermal forms of energy. Rewiring, network reconfiguration, installation of new lines and also new electrical and thermal generation units are considered as the traditional alternatives in expansion planning. To solve the problem, overall generation requirements of a network are assigned along the planning horizon. The allocation problem is formulated as a mixed‐integer non‐linear programming problem that minimises the overall system cost owing to generation capacity among the grid nodes and the newly added or upgraded lines. The performance of the original shuffled frog leaping (SFL) optimisation algorithm is advanced to overcome the complexity of the proposed expansion planning problem. Two modification steps were added to the original SFL technique to enable the proposed modified SFL algorithm to extricate from local minima. The two modification phases pledge a fast convergence rate by achieving a rapid adaptive algorithm, besides a better diversification which is the key to extricate from local minima. The efficacy and robustness of the proposed methodology are verified by applying the method to two modified standard test systems. [ABSTRACT FROM AUTHOR]

In this study, a stochastic multi‐objective framework is proposed for energy expansion planning (EEP). The proposed multiobjective framework can concurrently optimise the competing objective functions including total real energy losses, voltage deviation and the total cost of the installation equipments. Also, regarding the uncertainties of the new complicated energy systems, in this study, for the first time, system uncertainties including load uncertainty are explicitly considered in the EEP problem by the use of the probabilistic load flow technique based on the point estimate method. Since the objectives are different and incommensurable, it is difficult to solve the problem by the conventional approaches that may optimise a single objective. Hence, the metaheuristic algorithm is applied to this problem. Here, the particle swarm optimisation (PSO) algorithm as a new evolutionary optimisation algorithm is utilised. To improve the total ability of the PSO for global search and exploration, a new modification adaptive process is suggested in such a way that the algorithm will search the total search space globally. To evaluate the feasibility and the effectiveness of the proposed algorithm, three modified standard distribution systems are used as the case studies. [ABSTRACT FROM AUTHOR]

Objectives: Safety of intravenous thrombolysis (IVT) within 3-4.5 hours of stroke onset in patients ≥80 years is still disputable. We evaluated the association of symptom onset-to-treatment time (SOTT) with the symptomatic intracranial hemorrhage (sICH), poor outcome, and mortality in patients≥80 years., Materials and Methods: In a retrospective study, patients treated with IVT following stroke were registered. Outcomes were poor outcome (mRS>2), sICH/ECASS-2, and in-hospital mortality. We compared the patients≥80 years who received IVT within 3 hours with those receiving IVT within 3-4.5 hours. We further compared the patients who were <80 years with those ≥80 years and SOTT of 3-4.5 hours., Results: Of 834 patients, 265 aged over 80. In those above 80 and in multivariable analysis, the associations of SOTT with poor outcome (aOR: 1.401, CI: 0.503-3.903, p=0.519), sICH (aOR=2.50, CI=0.76-8.26, p= 0.132) and mortality (aOR=1.12, CI=0.39-3.25, p= 0.833) were not significant. 106 patients received IVT within 3-4.5 hours. In multivariable analysis, the associations of age (≥80 versus <80) with poor outcome (aOR=1.87, CI=0.65-5.37, p=0.246), sICH (aOR=0.65, CI=0.14-3.11, p=0.590), and mortality (aOR=0.87, 95% CI=0.16-4.57, p=0.867) were not significant in patients with SOTT of 3-4.5 hours., Conclusion: IVT within 3-4.5 hours in patients ≥80 years is not associated with increased sICH, poor outcome, and mortality compared to the early time window, and also compared to the younger patients in 3-4.5 hours window period. The decision of IVT administration in this age group should not be made solely on the basis of stroke onset timing., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)