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We demonstrate femtosecond ultra-stable green laser generation by an ytterbium-doped polarization-maintaining fiber laser with a 2.4 mm long lithium triborate (LBO) crystal. We generated 5.6 W of femtosecond green light at 520 nm for a fundamental power of 12 W, which corresponds to a conversion efficiency of 46.7%. The fiber chirped-pulse amplifier, which has an environmentally immune front end, delivered 170 fs pulses at a 75 MHz repetition rate centered at 1040 nm. According to the dispersion of the optical material in a double-frequency setup, the introduced dispersion had a negligible effect for the green laser, and the pulse duration of the generated green laser was calculated to be 171 fs, resulting in an excellent power stability, with fluctuation as low as 0.16% of the generated green light. This system could be of great interest in ultrafast optical and photobiology research. [ABSTRACT FROM AUTHOR]

The urgency of addressing climate change has underscored the necessity for implementing a new energy policy. Lately, an increasing number of countries and corporations have initiated the exploration of alternative energy sources to replace fossil fuels. There is a rising interest among individuals in photovoltaic solar panels as a sustainable means of generating electricity. Photovoltaic solar systems, on the other hand, rely significantly on weather conditions. As a result, the electricity generated by photovoltaic (PV) systems is unreliable. Harnessing biogas might serve as a captivating alternative for generating electricity. The study presents a proposal for a hybrid power system that combines PV solar panels and biogas. This system regards the PV solar system as the primary system. A forecast of PV production power is calculated using advanced machine-learning techniques. Subsequently, the projected power is juxtaposed with an approximation of the necessary load. If the PV system is unable to provide the necessary power demand, it is advisable to employ a biogas system to achieve a consistent and reliable power supply. Furthermore, this method offers a forecast of the daily waste demand for a reliable electrical grid. High-capacity manufacturing during the winter season is tested using a proposed solution for calculating biogas capacity and waste amount. The study introduces mathematical equations to address the daily biomass requirements of the system and implements an automated control system to oversee operations. The utilization of the proposed equations and control flow chart methodology effectively facilitates the precise quantification of methane generated from beef manure, reducing the margin of error from 12.82% to 8.28%. Additionally, it enables prompt adjustments to optimize equipment performance. This approach assists engineers in streamlining assessments and lays the groundwork for future improvements in design parameters.

The droop-controlled inverters (DCIs), which can simulate synchronous generators’ frequency and voltage behavior and provide active and reactive power support for the utility grid, are universally regarded as grid-friendly interfaces. This paper aims to give a general parameter design outline for the DCIs to simplify the complicated parameter tuning task while assuring good performances. For this purpose, the DCIs’ equivalent output impendence and admittance models are first developed, based on which the effects of parameters on impedance characteristics and power stability are analyzed in detail. Afterward, the general parameter design outline with a comprehending parameter tuning scheme is proposed based on the impedance analysis results. In the end, a 15-kVA prototype is established and tested in the laboratory. The experimental results verified the effectiveness of the proposed parameter design and optimization method.

We demonstrate femtosecond ultra-stable green laser generation by an ytterbium-doped polarization-maintaining fiber laser with a 2.4 mm long lithium triborate (LBO) crystal. We generated 5.6 W of femtosecond green light at 520 nm for a fundamental power of 12 W, which corresponds to a conversion efficiency of 46.7%. The fiber chirped-pulse amplifier, which has an environmentally immune front end, delivered 170 fs pulses at a 75 MHz repetition rate centered at 1040 nm. According to the dispersion of the optical material in a double-frequency setup, the introduced dispersion had a negligible effect for the green laser, and the pulse duration of the generated green laser was calculated to be 171 fs, resulting in an excellent power stability, with fluctuation as low as 0.16% of the generated green light. This system could be of great interest in ultrafast optical and photobiology research.

As the proportion of renewable energy generation systems increases, traditional power generation facilities begin to face challenges, such as reduced output power and having the power turned off. The challenges are causing changes in the structure of the power system. Renewable energy sources, mainly wind and solar energy cannot provide stable inertia and frequency regulation capability. Ultimately, the power system's emergency response capability to face an N-1 is reduced, which leads to a reduction in system stability. Therefore, the application technology of the battery energy storage system is used to support the impact of changes in the new power system structure. This paper designed control technologies based on the WECC second-generation generic model, namely, dynamic regulation, steady regulation, and virtual inertia regulation. The models and control strategies are verified on Taiwan's 2025 power system target conditions, which consider the expected capacities for battery energy storage systems, and renewable energy sources with different load and N-1 fault levels. According to the simulation results, the capabilities of the RoCoF limitation, frequency nadir, frequency recovery, and system oscillation regulation are evaluated in the proposed strategies. Finally, the analysis results can help power operators make informed decisions when selecting and deploying battery energy storage systems. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the unwanted chaotic oscillation that can severely affect the reliable and safe operation of electrical power systems. The dynamical behavior of a benchmark three-bus nonlinear electrical power system model is explored using modern nonlinear analysis methods, where the Lyapunov exponents spectrum, bifurcation diagram, power spectral density and bicoherence are used to investigate the chaotic oscillation in the power system. The analysis shows the existence of critical parameter values that may drive the power system to an unstable region and can expose the system to bus voltage collapse and angle divergence or blackout. To eliminate the chaotic oscillation, a fractional-order fixed time sliding mode controller has been used to control the power system in a finite time that can be predetermined by the designer. The Lyapunov theorem has been used to prove the stability of the controlled power system. The results confirm the superiority, robustness, and effectiveness of the suggested control algorithm. [ABSTRACT FROM AUTHOR]

Electrification rate is an internationally accepted index for electric power access. However, electrification rate data are only commonly available at the national level in underdeveloped countries. In this article, we proposed a power stability method to estimate the electrification rate using night-time light data. The essence of this method is constructing a power stability index viewed as a key parameter, which is derived from daily night-time light data, and the method considers both the reliability of electricity supply and the average power supply which is represented by the annual night-time light luminosity. We assumed that areas with unstable night-time light had no reliable power supply, and the Landscan population map was overlaid to estimate electrification rates in different regions. As a study case, we used the method to estimate the multispatial scale electrification rates in Zimbabwe. We validated the estimated province-level electrification rates using the statistical data. The overall accuracy was 85.42% with an R-Square of 0.98, indicating the method is accurate for estimating the electrification rate. Consequently, we generated an electrification rate map at the district-level, which provides rich spatiotemporal information of the electrification. This research highlights the potential of using multisource night-time light imagery to locate population without a stable electricity supply.

We examined the effect and influence of power stability of different commonly used lasers on the outcome of phase-stepping shearographic experiments. We performed power stability measurements with three different lasers (helium–neon laser, red diode laser and green frequency-doubled neodymium laser). We subsequently performed phase-stepping shearography experiments using these lasers as light sources. We found a correlation with the quality of the shearograms and the power stability of the lasers. This enables us to compare the suitability of various lasers for phase-stepping shearography experiments and to choose the best laser for this application.

The power stability in power distribution systems are well studied. There exist numbers of models towards maintaining the power stability which consider the residual energy of PV systems. However, there are not efficient in maintaining the power stability and suffer to achieve higher efficiency in potential maximization. Towards maintaining higher potential maximization, an efficient Optimized Solar Potential Maximization Model (OSPMM) is presented in this article. The model considers the factors like Mean Voltage Generation, Mean Voltage Supply and Residual Voltage as the key in the selection of PV system towards power stability. To perform this, the method monitors the incoming voltage produced by various PV systems and collects such factors mentioned above. According to the factors identified, the method estimates Potential Maximization Support (PMS) for various PV systems. Based on the value of PMS, the method selects the PV system towards maintaining power stability. The proposed approach improves the performance of solar potential maximization and power stability maximization.

The problem of power stability in electrical systems has been well analyzed. There exist number of approaches to handle the issue which consider the factors like residual energy in various power grids of the system. However, they suffer to achieve higher performance in power stability. To handle this issue, an efficient deep learning based voltage switching model (DLVSM) is presented in this article. The proposed model adapts deep neural network towards the selection of electrical circuit from the list of serially connected grids. As the grids have their own residual energy and varying voltage production, the proposed model trains the network with different features like average voltage generation, average output voltage and residual energy. Using all these factors, the neurons are designed to measure the Optimized Power Stability Factor (OPSF) for various patterns of grid circuit. The network is designed with number of intermediate layers where each layer has set of neurons which estimates the Power stability factor (PSF) for specific grid unit. The output layer neurons estimates OPSF value for various sequences of grids. Based on the value of OPSF, the proposed model identifies a specific sequence and performs voltage switching to maintain the power stability in the electrical systems. The proposed model improves the performance of power stability and reduces voltage loss.

Towards effective voltage regulation and power stability, there exist number of approaches available in literature. The methods consider the residual voltage in various power grids in maximizing the power stability. However, the methods suffer to achieve higher performance in power stability and voltage regulation. To handle this issue, an efficient Electric Patter Based Voltage regulation model (EPVRM) is presented in this article. The method maintains the voltage trace belongs to various grids of the power system. Using the traces maintained, the method preprocesses the traces to remove the noisy records. The preprocessed trace has been used to generate the electrical pattern which contains residual voltage of various grid units. Using the electric pattern the method computes Electric Pattern Stability Support (EPSS) towards the required voltage. Based on the EPSS value, the method identifies the most efficient pattern to be scheduled for current cycle. The selected pattern has been scheduled to maintain the power stability. The proposed method improves the performance of voltage regulation and power stability.

The photoinjector laser system of Shenzhen Superconducting Soft X-Ray Free Electron Laser (S3FEL) is reported in this paper. This laser system operates at up to 1 MHz and produces more than 50 μJ infrared (IR) laser pulses. With a customized fourth harmonic generation (FHG) module, more than 2 μJ ultraviolet (UV) laser pulses were obtained. The power standard deviations of the IR laser and the UV laser are 0.093% and 0.395% respectively. While the pulse energy standard deviations are 1.087% and 1.746% correspondingly. We implemented the pulse stacking scheme to generate flat-top pulses. With four birefringent uniaxial crystals, the Gaussian pulses were converted to flat-top shape, featuring 10 ps pulse width and 0.5 ps rising and falling edges. A cut-Gaussian transverse profile with very sharp rising and falling edges can be produced after the spatial pulse shaper.

Marine energy, as a renewable and environment-friendly energy, has presented promising solutions amid consumers' green concerns. However, manufacturers have to take the risk of marine energy's supply instability and green competition with market competitors. This study therefore investigates two competing manufacturers' equilibrium power strategies when they decide whether to use marine energy. We define the manufacturer's use of electricity from a fossil fuel power supplier as strategy T , and from a marine energy power supplier as strategy M. Our findings indicate that four strategy combinations may sustain as the equilibriums: T T , M T , T M and M M , depending on the sophisticated interactions of consumers' environmental concerns, marine energy stability and competition intensity. We identify the marine energy advantage and the demand shrinking effect to interpret the main findings. The marine energy advantage refers to the increased demand from eco-friendly consumers when using marine energy. The demand shrinking effect refers to the narrowing of demand due to increasing product homogeneity. We further find that the different competition landscapes drive power suppliers to adjust their power prices and thus affect the equilibriums, which is defined as the power price effect. Interestingly, we show that consumers' green concern may lead to a worse environmental performance because green demand is created but marine energy supply instability will induce the manufacturer with a larger demand size to opt for polluting and stable fossil energy power. • Two power strategies are formulated for energy supply chain operations • A two-pronged approach to technology development and green education can better drive manufacturers to use marine energy. • Economic and environmental performances under four strategy combinations are evaluated • Consumers' green concern may lead to a worse environmental performance under certain conditions [ABSTRACT FROM AUTHOR]

• The active power and reactive power coupling principle of the conventional grid-forming photovoltaic DC/AC converter is analyzed. • A reactive power decoupling control strategy is proposed. • The impact of key parameters on the grid-forming photovoltaic stability is analyzed. • The controller hardware-in-the-loop experiment is designed for verification. The grid-forming photovoltaic system (GFM-PV) can actively build up voltage without relying on the grid and exhibit voltage source characteristics. This paper proposes a reactive power decoupling control strategy for the problem of active and reactive power coupling in GFM-PV. Firstly, this paper analyzes the coupling principle of the active power and the reactive power of the GFM-PV DC/AC converter and proposes the reactive power decoupling control strategy. Then, this paper studies the influence of the DC/AC converter key parameters on the power stability of GFM-PV based on impedance analysis. Finally, the controller hardware-in-the-loop (C-HIL) experiments verify the effectiveness of the control strategy proposed in this paper and the correctness of the theoretical analysis. [ABSTRACT FROM AUTHOR]

As the proportion of renewable energy generation systems increases, traditional power generation facilities begin to face challenges, such as reduced output power and having the power turned off. The challenges are causing changes in the structure of the power system. Renewable energy sources, mainly wind and solar energy cannot provide stable inertia and frequency regulation capability. Ultimately, the power system’s emergency response capability to face an N-1 is reduced, which leads to a reduction in system stability. Therefore, the application technology of the battery energy storage system is used to support the impact of changes in the new power system structure. This paper designed control technologies based on the WECC second-generation generic model, namely, dynamic regulation, steady regulation, and virtual inertia regulation. The models and control strategies are verified on Taiwan’s 2025 power system target conditions, which consider the expected capacities for battery energy storage systems, and renewable energy sources with different load and N-1 fault levels. According to the simulation results, the capabilities of the RoCoF limitation, frequency nadir, frequency recovery, and system oscillation regulation are evaluated in the proposed strategies. Finally, the analysis results can help power operators make informed decisions when selecting and deploying battery energy storage systems.

This study investigates the power systems that involve various numbers of busbars. To prevent the disturbances and instabilities in the power systems, power system stabilizers and various control methods have been used. A hyperchaotic blackout has been created by using an existing hyperchaotic system. Hyperchaotic voltage collapse and hyperchaotic disturbance have been injected to the test systems. The situations of the various power systems are illustrated under proposed hyperchaotic blackout and noise. The stability analysis of the power system has been executed according to the dynamic features of hyperchaos.

The rapid development of society has led to a rapid increase in the demand for electricity and the scale expansion of power systems, and their stable operation is a top priority. This paper briefly introduced the structure of the photovoltaic microgrid and the electrical automation control strategy for stable grid-connected microgrid operation, improved the electrical automation control strategy with the extreme learning machine (ELM) algorithm, and conducted simulation experiments on two electrical automation control strategies in MATLAB software. The results showed that the voltage of the microgrid fluctuated when the load in the microgrid and the output of the photovoltaic power supply changed, and both automatic control strategies suppressed the fluctuations, and the improved automation control strategy had a better suppression effect and took less time to restore microgrid stability. [ABSTRACT FROM AUTHOR]

Distributed generation (DG) has environmental as well as economic benefits and develops new concepts to make the power network more effective and minimize pollution in the environment. Being the fluctuation behavior of renewable energy sources (RESs), generation, balance, and demand is not an easy task to control because it is not desirable to have a constant power generation from RESs due to natural prospects. As a result, the dynamic stability of power flow and control of frequency is becoming more challenging due to the high penetration impacts of RESs. In this article, we have proposed a control algorithm with two scenarios for a high-penetration/hybrid diesel wind-based energy storage system to maintain the dynamic stability of power flow and control the frequency in the overall power system. The results show, using an integral–derivative (I–D) controller, the transient time of wind power flow and the fluctuation rate of frequency are reduced significantly compared to the prior research of publication. To regulate the network frequency, a storage system (battery) was used to store the excess energy without throwing it to the secondary/dump load (DL) and minimize the wastage of power produced by the wind turbine. The battery was supplied the excess wind power when there is a high load demand. [ABSTRACT FROM AUTHOR]

The number of transient operations in hydraulic machinery connected to power grid, notably start-ups and shut-downs, has observed a substantial increase in recent decades, primarily driven by the global shift towards intermittent renewable energy sources. Simultaneously, advancements in MW power converter technology and its cost-effectiveness have altered the operational paradigms of hydropower plants. These transformations offer novel opportunities for asset management within the industry. This study introduces a new method aimed at forecasting stress during start-up procedures, leveraging steady-state measurements acquired from a reduced scale model of the hydraulic turbine. Through a dedicated modular telemetry measurement system and the integration of strain gauges onto the reduced-scale runner blades, a tool is devised to predict dynamic loads characteristic of these transient operations. Utilizing steady-state measurements and a Voronoi cell tessellation, the transient predicted stress signal is constructed by concatenating the information from each encountered cell, thus providing an estimated projection of the stress likely to occur during the sequence. The proposed methodology demonstrates a robust forecast of the stresses on the runner blades during steady-state and transient operations of Francis turbines. Its immediate value lies in the ability to correctly estimate the lifetime of the runner as well as the possible integration into an optimization framework for stress reduction, thereby potentially extending the operational lifespan of the unit, from the runner structure perspectives. • Experimental investigations using a reduced-scale model equipped with embedded sensors. • Methodology for accurately forecasting dynamic loads during diverse transient operations. • Assessing and determining the remaining lifespan of hydraulic machinery through estimation techniques. • Optimization tool for reducing damage induced by transient operation. [ABSTRACT FROM AUTHOR]

Smart Grid (S.G.) is a digitally enabled power grid with an automatic capability to control electricity and information between utility and consumer. S.G. data streams are heterogenous and possess a dynamic environment, whereas the existing machine learning methods are static and stand obsolete in such environments. Since these models cannot handle variations posed by S.G. and utilities with different generation modalities (D.G.M.), a model with adaptive features must comply with the requirements and fulfill the demand for new data, features, and modality. In this study, we considered two open sources and one real-world dataset and observed the behavior of ARIMA, ANN, and LSTM concerning changes in input parameters. It was found that no model observed the change in input parameters until it was manually introduced. It was observed that considered models experienced performance degradation and deterioration from 5 to 15% in terms of accuracy relating to parameter change. Therefore, to improve the model accuracy and adapt the parametric variations, which are dynamic in nature and evident in S.G. and D.G.M. environments. The study has proposed a novel adaptive framework to overcome the existing limitations in electrical load forecasting models. [ABSTRACT FROM AUTHOR]

We developed a new strength measure, the hybrid multi-infeed effective short-circuit ratio (HMESCR), for evaluating hybrid multi-infeed high-voltage direct current (MIDC) systems. The HMESCR defines the strength of hybrid MIDC systems with line-commutated converter (LCC) high-voltage direct current (HVDC) and voltage-source converter (VSC) HVDC systems. Unlike previous measures, the HMESCR considers the capacity of VSC HVDC systems to provide reactive power and thus, enhance the strength of AC systems connected at different buses with LCC HVDC systems. To demonstrate how the HMESCR reflects power stability (PS) and temporary overvoltage (TOV), we used MATLAB/Simulink software to perform quasi-steady-state analyses and dynamic simulations. The HMESCR can be used to determine the strength of hybrid MIDC systems. [ABSTRACT FROM AUTHOR]

Compared to air surroundings, the marine environment is not stable due to the influence of ocean currents and other factors. Misalignments always occur inevitably when autonomous underwater vehicles are charging wirelessly in the docking station. Therefore, misalignment insensitive underwater wireless power transfer system need to be investigated. In this article, a novel hybrid transmitter composed of conical and planar spiral coils is proposed that greatly improves the misalignment tolerance and transfer performance. First, the coil tilt angle theory (CTAT) is presented and verified to determine the optimum tilt angle of conical coil. Then, based on the CTAT, a circular uniform magnetic field zone with a diameter of 30 cm in charging plane can be achieved by flexibly designing the hybrid transmitter. Moreover, a three-dimensional finite-element simulation software is employed to study the eddy current loss under different circumstances. Finally, experimental results show that the proposed transmitter has better performance in output power and power transfer efficiency (PTE) stability within the possible working region compared with conventional transmitters. It has demonstrated that the output power changes only within 5.7% and the PTEs maintain at approximately 86% in excessive misalignment area with transfer distance of 2 cm. [ABSTRACT FROM AUTHOR]

Load shedding plays a key part in the avoidance of the power system outage. The frequency and voltage fluidity leads to the spread of a power system into sub-systems and leads to the outage as well as the severe breakdown of the system utility. In recent years, Neural networks have been very victorious in several signal processing and control applications. Recurrent Neural networks are capable of handling complex and non-linear problems. This paper provides an algorithm for load shedding using ELMAN Recurrent Neural Networks (RNN). Elman has proposed a partially RNN, where the feedforward connections are modifiable and the recurrent connections are fixed. The research is implemented in MATLAB and the performance is tested with a 6 bus system. The results are compared with the Genetic Algorithm (GA), Combining Genetic Algorithm with Feed Forward Neural Network (hybrid) and RNN. The proposed method is capable of assigning load releases needed and more efficient than other methods.

One of the confrontations with increasing demand on power in the entire world the methodologies of provided power divided into traditional methods against renewable methods. This article presents a simulation model to estimate the integrated power from vertical access wind turbine (VAWT) stages of development of a simulation model of local power supply system (LPSS) with (VAWT). However, wind power is one of the quickest developing advances for the sustainable power age. Disturbingly, in the ongoing years a few instances of corruption on telecommunication systems frameworks have emerged because of the presence of wind ranches, and costly and in fact complex restorative estimations needed. The grade of variation of power verified according to the grid size. The parameters were taken in the study through the preparation of the model are (efficiency, cost, and system response) compared to the benefits against disadvantages when combining the two systems to achieve a high performance of the power stability. [ABSTRACT FROM AUTHOR]

This paper analyzes the power stability of the hybrid dual-infeed high-voltage direct-current (HVDC) system containing a line commutated converter-based HVDC (LCC-HVDC) and a voltage source converter-based HVDC (VSC-HVDC). First, the concept and the calculation method of power stability for the hybrid dual-infeed HVDC system are introduced. Second, the influence of VSC-HVDC on the power stability of the system is investigated. Third, the relationship between the power stability and the effective short circuit ratio (ESCR) is discussed under different system parameters. Then, the value range of the critical effective short circuit ratio is determined. Finally, the evaluation criteria of power stability are proposed. The results show that the evaluation criteria of the single-infeed LCC-HVDC system can still be used, if the VSC-HVDC is in constant AC voltage control mode; if the VSC-HVDC is in constant reactive power control mode, the hybrid dual-infeed HVDC system cannot operate stably when the ESCR is less than 2.0 and can operate stably with high power stability margin when the ESCR is greater than 3.0. The ESCR index can still be used to measure the power stability of the hybrid dual-infeed HVDC system. [ABSTRACT FROM AUTHOR]

Based on the analysis of the relationship between the voltage sensitivity of the receiving system and the DC power stability, an evaluation index, Receiving System Voltage Support Strength Factor (RVSF), is proposed in this paper for identifying the voltage support strength of the receiving system. The threshold of RVSF is derived and used as the criteria for distinguishing the voltage support strength of the receiving system. The critical Receiving System Voltage Support Strength Factor (CRVSF) can keep constant in receiving systems which operate in different modes. Furthermore, the analytical expression of RVSF is derived from the Jacobian matrix form of the incremental flow equation of the AC system. By deriving the relationship between RVSF and power stability and considering the constraint of commutation angle, it can be obtained that the receiving system is a very weak system when RVSF2. Finally, the performance of RVSF and other widely used system strength indicators such as effective short circuit ratio (ESCR) and multi-infeed effective short circuit ratio (MIESCR) are compared and analyzed. Compared with other indicators, it is found that RVSF has a clear threshold when measuring the strength of different receiving systems.

High-voltage direct current (HVDC) transmission is playing an increasingly important role in modern power systems, and the resulted power/voltage stability issue has raised widespread concern. This paper presents an on-line power/voltage stability index (PVSI) for multi-in-feed HVDC (MIDC) systems. Different from the existing indices which are developed mainly for off-line and static analysis, the proposed PVSI can be applied in real time. Effects of system changes on stability assessment such as change of system states and control strategies are considered. Thus, helpful guidance can be provided for on-line HVDC stability and controls. The PVSI is originally deduced for single-infeed HVDC systems in an “AC way” by analyzing the power and voltage stability of both pure AC systems and HVDC systems. Moreover, its on-line application in practical MIDC systems is realized by building an equivalent single-infeed model, and utilizing nowadays measurement and communication infrastructures such as wide-area measurement system (WAMS). The effectiveness of the PVSI is verified through simulations in real-time digital simulator (RTDS).

With the conversion of the global power economy and energy structure, access to a large amount of renewable energy has led to a decrease in power system inertia. The slight abnormal disturbance in the distribution network may have a significant impact on social and economic development. Aim at enhancing power stability and system resiliency; this study focuses on the detection and location of multiple abnormal sources in the distribution network. Most traditional methods use models relying on precise line parameters, subject to poor adaptability to the distribution network with a large number of nodes, and rapidly changing topology. Therefore, this study proposes a novel random matrix model, driven by monitoring data from phasor measurement units distributed on the overhead transmission lines. In this model, linear shrinkage (LS) theory, and Marchenko–Pastur law are combined for noise reduction to ensure the dynamic character and anti-noise ability. Moreover, data dimensions and sample points may be at the same level in an extensive scale network. The LS and standard condition number rule (SCN) are used for estimating the number of abnormal sources. Finally, the effectiveness of this paper's model is verified in PSCAD. The results indicate that the method has specific dynamic performance and anti-noise ability. [ABSTRACT FROM AUTHOR]

Matching of the colossal energy demand with carbon‐free resources originates a global challenge to produce and innovate advanced energy technologies that generate clean and friendly energy supplies without threatening our environment. Nevertheless, with the increase in the penetration from renewable energy resources like solar and wind farms many technical issues are presented typically; power stability, power quality, and frequency fluctuations. The aforementioned problems stem from the intermittent nature of renewable resources which makes the generated power unpredictable and requires controlling and smoothing before dispatching. Conventionally low pass filter (LPF) is used with a controlled energy storage system to smoothen the fluctuated power due to its simplicity, but a delay problem increases with higher values of the filtering the time constant. This study suggests a smoothing controller‐based fuzzy logic that determines the value of the filtering time constant based on the present solar power ramp rate to avoid the battery overworking, which results in the predetermined configuration of the LPF. The presented simulation results prove the smoothing performance of the proposed controller and compare its performance to the LPF during clear, normal, and cloudy irradiance profiles. [ABSTRACT FROM AUTHOR]

Summary: The presence of electric vehicles (EVs) directly affects the low voltage electric distribution networks. This article depicts the anticipated problems that occurred when it draws power from grid to vehicle in the charging scenario and critically analyze EV as dynamic storage while feeding the power grid in the discharging status (vehicle to grid). The merits and demerits by deploying the mass integration of EVs into the distribution network are comprehensively investigated. Moreover, the challenges of integrating renewable energy resources and deployment of EVs, for the efficient, reliable, and uninterruptible power flow are covered. The future scopes of electric mobility industry including wireless EV charging, vehicle to home, cloud to home charging are also highlighted. This comprehensive review is highly beneficial for the research community and design engineers working in this area. [ABSTRACT FROM AUTHOR]

Major changes in the technologies of power generation and distribution systems have been introduced in recent years due to concern over rapid climate change. Therefore, disturbances in the large-scale generation, transmission, and distribution of energy are expected to occur in the near future. This is due to the difficulty in controlling the transmission and distribution of energy produced from renewable energy sources (RESs), caused by the instability of these sources and the intermittent nature of their energy. As a result, maintaining the dynamic stability of wind power flow and control of the network frequency is becoming more challenging due to the high penetration impacts of RESs. In this paper, a control algorithm using the power-sharing method is proposed for a wind-based energy storage system to maintain the dynamic stability of wind power flow and control of frequency in the power network. To maintain the network stability, a storage system (battery) was installed to store the excess wind power without throwing it into the Secondary/Dump Load (SL) and minimize losses in power generated by the wind turbine. The results show, the transient time of wind power flow and the fluctuation rate of frequency are reduced significantly using a Fuzzy Logic (FL) controller compared to the Proportional Integral Derivative (PID) controller.

The separating pole connection (SPC) mode of ultra-high-voltage direct current (UHVDC) can significantly improve the power stability, but when the AC bus of one pole is failed and two receiving systems are near, it may cause subsequent commutation failure. In order to restrain subsequent commutation failure and accelerate system's recovery, an adaptive voltage-dependent current order limiter (VDCOL) control strategy based on granular computing is proposed. According to this VDCOL control strategy, VDCOL, which uses fuzzy rules to separate and granulate a different voltage level, can adjust DC current dynamically in a variety of environments. Also, some modifications on VDCOL characteristics are applied to reduce reactive power consumption during low-voltage situations. Then based on the MATLAB simulation platform, the simulation systems for 800 kV the UHVDC SPC system are built. Finally, the simulation example of the SPC mode with the adaptive VDCOL control strategy showed that this VDCOL control strategy can reduce the risk of subsequent commutation failure and improve the stability of the AC/DC interconnection system.

This paper analyzes the power stability of the hybrid dual-infeed high-voltage direct-current (HVDC) system containing a line commutated converter-based HVDC (LCC-HVDC) and a voltage source converter-based HVDC (VSC-HVDC). First, the concept and the calculation method of power stability for the hybrid dual-infeed HVDC system are introduced. Second, the influence of VSC-HVDC on the power stability of the system is investigated. Third, the relationship between the power stability and the effective short circuit ratio (ESCR) is discussed under different system parameters. Then, the value range of the critical effective short circuit ratio is determined. Finally, the evaluation criteria of power stability are proposed. The results show that the evaluation criteria of the single-infeed LCC-HVDC system can still be used, if the VSC-HVDC is in constant AC voltage control mode; if the VSC-HVDC is in constant reactive power control mode, the hybrid dual-infeed HVDC system cannot operate stably when the ESCR is less than 2.0 and can operate stably with high power stability margin when the ESCR is greater than 3.0. The ESCR index can still be used to measure the power stability of the hybrid dual-infeed HVDC system.

A tunable erbium-doped fiber laser (EDFL) is proposed and demonstrated experimentally. It is based on a tunable fiber filter using the pump induced refractive index change characteristics of the Er/Yb codoped phosphosilicate fiber (EYDF) based modal interferometer (MI). The laser achieves a tunability of 2.39 nm and 1.60 nm, with the wavelength linearly tuned from 1534.05 nm to 1536.44 nm and from 1554.36 nm to 1555.96 nm by changing the pump power injected into the MI. Its side mode suppression ratios are 30 dB and 33 dB, respectively. The stability of the tunable EDFL is getting better with the continuous improvement of the power of pump 1, and the dual-wavelength power fluctuations are less than 0.22 dB and 0.12 dB within 20 min at 250 mW of pump 1, respectively. [ABSTRACT FROM AUTHOR]

The separating pole connection (SPC) mode of ultra-high-voltage direct current (UHVDC) can significantly improve the power stability, but when the AC bus of one pole is failed and two receiving systems are near, it may cause subsequent commutation failure. In order to restrain subsequent commutation failure and accelerate system's recovery, an adaptive voltage-dependent current order limiter (VDCOL) control strategy based on granular computing is proposed. According to this VDCOL control strategy, VDCOL, which uses fuzzy rules to separate and granulate a different voltage level, can adjust DC current dynamically in a variety of environments. Also, some modifications on VDCOL characteristics are applied to reduce reactive power consumption during low-voltage situations. Then based on the MATLAB simulation platform, the simulation systems for 800 kV the UHVDC SPC system are built. Finally, the simulation example of the SPC mode with the adaptive VDCOL control strategy showed that this VDCOL control strategy can reduce the risk of subsequent commutation failure and improve the stability of the AC/DC interconnection system. [ABSTRACT FROM AUTHOR]

The article examines the current problems of improving the legal norms governing elections of the highest officials of Russian Federal entities, considers the problematic issues of the implementation of electoral mechanisms in the context of the subjects of the nomination of candidates, the features of the legal regulation of the institution of self-nomination in the elections of the highest official of Russian Federal entities. The authors analyze the legal norms that regulate the procedure for collecting signatures in support of candidates nominated by various subjects, consider the organizational and legal norms that regulate the procedure for recalling the highest official of the Russian Federation, and suggest ways to improve the regulatory and legal regulation of the election of the highest official of the Russian Federal entity.

Building a multi-energy complementary power generation system is a viable way to encourage the use of renewable energy and decarbonize power generation. However, the intermittent nature of renewable power generation, such as photovoltaic and wind power, has prompted concerns regarding power grid stability. To balance such fluctuations, energy storage systems or other flexible power generation technologies should be integrated. In this paper, the peak regulation ability of integrated solar combined-cycle has been enhanced via employing a gas/oil exchanger between the top and bottom cycle. When integrating high penetration intermittent renewable energy, an appropriate operational strategy towards high-quality steady power output regulation is proposed. Dynamic performance analysis of the system, coupled characteristic of heat and mass transfer between subsystems have been highlighted. The case study demonstrates that fluctuations of the multi-energy complementary system power output can be controlled below 0.3 MW without renewable energy curtailment, even though wind-PV power generation fluctuates from 0.3 MW to 26.1 MW with variations per second reaching −2.8/3.7 MW. Furthermore, the system's levelized cost of electricity is down to 0.0512 $/kWh, which is cost-competitive with conventional power generation technologies. • Combination of integrated solar combined cycle with wind and PV power plant. • Power stability of system with high penetration intermittent energy. • Novel system configuration and operation strategy. • Deviations from target power output below 0.3 MW per second. [ABSTRACT FROM AUTHOR]

In this paper, we introduced an intermittent wave energy generator (IWEG) system with hydraulic power take-off (PTO) including accumulator storage parts. To convert unsteady wave energy into intermittent but stable electrical output power, theoretical models, including wave energy capture, hydraulic energy storage, and torque balance between hydraulic motor and electrical generator, have been developed. Then, the integrated IWEG simulator was constructed and tested at the Ningbo Institute of Technology. Through a series of experimental tests, the relationship between operating flow rates and pressure drops across the hydraulic motor was established. Furthermore, on the basis of the pressure drop signal, we proposed a feedback control method on the basis of the pressure drop database as the feedback control signal to eliminate the disturbance of periodic peak pressure impulse through the regulation of the opening ratio of a proportional flow valve and achieved the effective and stable electric power output, albeit intermittently. Compared with the previous complex control theories and algorithms, this method can keep the power output more stable over a wide range of operating conditions. Furthermore, experimental tests indicate that the IWEG system, with hydraulic PTO, including hydraulic accumulator and proportional flow control valve, is simple, reliable, and easy to control. Most importantly, the real-time power output is stable, and power quality and generation efficiency are significantly improved. [ABSTRACT FROM AUTHOR]

With the development of ultra-high-voltage direct current (UHVDC) transmission systems, the receiving AC systems face the problems of power flow transferring, integrating capability and voltage stability. A novel UHVDC hierarchical connection (HC) mode has been proposed and adopted in several real projects in China. The more complex electric coupling relationship of the entire systems made the power interaction characteristics different from those of previous multi-infeed HVDC systems. Thus, it is important to analyze the power stability of such systems in a systematic manner to avoid adverse interactions. In this study, the equivalent model of HC-UHVDC systems is established and several evaluation indices concerning power stability are discussed and improved. Furthermore, the power integration capability and reactive power interaction are evaluated based on real data. The results of this research can be used to provide technical support to real HC-UHVDC projects. [ABSTRACT FROM AUTHOR]

Magnetic resonance-based wireless power transfer system offers a promising solution to overcome power limitations typically encountered by capsule endoscopy. Despite of much attention in this area, aspects such as power stability and power transfer efficiency remain suboptimal and therefore investigation for further improvement is still required. This paper presents a method to improve power stability as well as power transfer efficiency for wireless capsule endoscopy. A new power transmission coil capable of producing uniform magnetic field is proposed to improve power stability through uniform field that at the same time minimizes the unnecessary peak electromagnetic exposure. To improve power transfer efficiency, a mixed resonance scheme is employed. Our experimental results show improvement over existing methods where the proposed system attained power stability of 94.62% and power transfer efficiency of 4.9% under worst position of the receiving coil. Furthermore, the proposed transmitting coil provides additional advantage, where it minimized the unnecessary peak electromagnetic exposure by 26% as compared to the conventional Helmholtz coil-based system. We believe the proposed system will open new direction for future wireless capsule endoscopy and can also be useful in other industrial applications. [ABSTRACT FROM AUTHOR]

In view of problem that traditional PID control for synchronous generator cannot meet with requirements of oscillation suppression and improvement of dynamic stability limit of power system, the paper proposed the optimal excitation control method for synchronous generator based on AC tracking. It gave deviation and linearization model of excitation system of synchronous generator based on Lagrange method, analyzed definition method of the optimal excitation control quantity and built simulation model of synchronous generator system based on the control method. The simulation result showed that the control method can real-timely control excitation system of synchronous generator to ensure output stability of synchronous generator comparing with traditional PID control method.