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This paper presents a novel methodology for modeling hydropower plants (HPPs) with and without pumping capability in resource adequacy assessment studies. The proposed method is based on the premise that HPPs should maximize their contribution to system adequacy within their technical constraints by using the energy reserves in their upper reservoirs without significantly deviating from their market schedule. The approach of this paper differs from the conventional operating policies for incorporating HPPs into resource adequacy assessment studies, which either adhere to a fixed market schedule or perform peak shaving, and are inelastic to real-time events or do not resort to realistic temporal correlations between natural water inflows on upper reservoirs and the water discharge needs to cover demand peaks, respectively. The modeling approach focuses on large-reservoir HPPs with natural inflows and is generic enough to deal with both stations incorporating pumping capabilities and those without. It utilizes the state-of-the-art Monte Carlo simulation technique to form the availability of system assets and determine the loss of load incidents. The market schedule and level of reservoir fulfillment for the HPPs are retrieved from a cost-optimal power system simulation algorithm executed offline before the application of the resource adequacy assessment. The effectiveness of the proposed methodology is demonstrated through its implementation in a case study of a power system experiencing different levels of adequacy, comparing the obtained results with various traditional HPP modeling methods from the literature. [ABSTRACT FROM AUTHOR]

The integration of new battery technologies has become a focal point for distribution utilities, driven by decreasing costs and the need for fast responsiveness. Transportable battery energy storage systems (TBESSs) offer additional flexibility, allowing connection at multiple substations or grid feed points. However, concerns remain regarding their impact on distribution systems (DSs), particularly on protection devices (PDs). This study addresses these concerns by investigating the influence of TBESSs on the protection systems of a real-world distribution network. Given the lack of studies in the current literature on this topic, this research aims to fill this gap by examining the potential effects of TBESS integration on PDs, such as reclosers and fuses, within a DS. Utilizing a model based on real data from a Brazilian utility, we conducted simulations to analyze the effects of TBESSs in both charging and discharging modes on the protection systems of three feeders. The methodology involved assessing variations in the operation times and coordination of PDs to determine if TBESS integration would necessitate adjustments to existing protection configurations. The results demonstrated that TBESS integration resulted in only minor variations in PD operating times, typically within hundredths of a second, indicating a negligible impact on protection performance. Consequently, no significant modifications to the protection system are required to accommodate TBESSs. These findings suggest that TBESSs can be seamlessly integrated into existing distribution networks, maintaining system reliability and operational integrity. This study provides valuable insights and a robust procedure for utilities to analyze the integration of TBESSs, supporting the effective deployment of modern energy storage solutions in DSs. [ABSTRACT FROM AUTHOR]

From time to time, a series of unpredictable and conflicting contingencies can lead to angular instability of the power system and even blackouts if not adequately handled by an out-of-step (OOS) protection system. The key contribution of this research work, to the theory of out-of-step protection, is the identification and isolation after a given disruption of many unstable swings. This paper presents a proposed method to avoid false operation for distance function by out-of-step blocking to improve the system stability by using optimally placed PMUs for the fast detection of system analogue quantities. The studies were performed on a modified Eskom transmission network in the Western Cape with 765 kV and 400 kV voltage levels. The aim is to investigate the IEC 61850-90-5 standard for predictive dynamic stability maintaining systems using PMUs for out-of-step conditions of synchronous generators. The power system modelling and simulation are performed in the RSCAD-FX for the proposed multi-area power system network. An experimental lab-scale implementation is built to test the proposed out-of-step algorithm in a real-time digital simulator. Software-based PMU is incorporated to test and validate the IEC 61850-90-5 standard sampled values. Simulation and experimental results are presented. [ABSTRACT FROM AUTHOR]

The deployment of Electrically Trace Heated Pipe-in-Pipe (ETH-PiP) brings the challenges of reliable protection selection and setting. This paper presents a study of relays and protection function optimization for ETH-PiP systems. The study is based on the developed simulation model of a typical ETH-PiP system. The paper presents simulation studies of physical phenomena occurring during electrical disturbances in the ETH-PiP system and offers detailed analyses applicable to system protection, including detection of disturbances, location, and elimination. [ABSTRACT FROM AUTHOR]

A systematic definition of an aircraft generator's "available power" (used to supply loads on its DC bus) is given, which is defined in the context of constraints on transient and steady‐state performance. Using a geometric, data‐driven approach, such a characterisation has been achieved, and a new method, called Power availablE Estimation Tool (PEET), has been developed to determine in real‐time whether a given load can be fulfilled at a given time while maintaining power quality. This is an important problem, especially for safety critical electrical systems such as more electric aircraft, for which it is imperative to know a priori whether an added load will result in voltage variations outside of allowed values. PEET is introduced and its conceptual framework is formalised. Lastly, it provides simulation results that illustrate its performance. The results show that the PEET method produces reliable a priori estimates of power availability, and that this can be achieved within time frames that make it applicable in a real‐time implementation. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of an improved resonance-type FCL, designed to enhance the transient stability of a photovoltaic farm. This FCL overcomes the well-known drawbacks associated with the conventional resonance-based FCLs. This FCL limits the fault during the fault period, quickly achieves stability during the recovery period, independent of the reactor's charging state, and notably reduces DC-link voltage fluctuations during faults. A power system simulation setup comprising a PV farm, synchronous generator, transformers, circuit breakers, transmission system, and several branches of loads is used for testing the proposed FCL. The simulation results validate that the proposed FCL better improves the system's stability and leads to improved fault current, PCC voltage, active power, reactive power, and DC-link voltage compared to other common types of resonant FCLs. [ABSTRACT FROM AUTHOR]

This paper proposes a new comprehensive load restoration (LR) method for electrical distribution networks. Since two main technologies of switching equipment are there in the modern distribution networks, namely manual switches (MSs) and remote‐controlled switches (RCSs), this article has benefited from this concept effectively. A two‐stage algorithm that provides the system operators with the ability to recover part of the loads in the shortest possible time by RCSs is proposed. After this step, the remaining loads will be restored by a combination of MSs and RCSs. The other strength of this algorithm is to provide accurate and practical solutions so that the sequence of switching actions is clearly defined. Also, using an innovative index called expected weighted energy not supplied as the objective function of the main problem will ensure the operators recover the maximum amount of load in the shortest time possible. This novel method was applied on a sample standard IEEE distribution test network. The simulation results proved the effectiveness of this proposed method. [ABSTRACT FROM AUTHOR]

This paper sets out to develop an efficient probabilistic optimal power flow (POPF) algorithm to assess the influence of wind power on power grid. Given a set of wind data at multiple sites, their marginal distributions are fitted by a newly developed generalized Johnson system, whose parameters are specified by a percentile matching method. The correlation of wind speeds is characterized by a flexible Liouville copula, which allows to model the asymmetric dependence structure. In order to improve the efficiency for solving POPF problem, a lattice sampling method is developed to generate wind samples at multiple sites, and a logistic mixture model is proposed to fit distributions of POPF outputs. Finally, case studies are performed, the generalized Johnson system is compared with Weibull distribution and the original Johnson system for fitting wind samples, Liouville copula is compared against Archimedean copula for modelling correlated wind samples, and lattice sampling method is compared with Sobol sequence and Latin hypercube sampling for solving POPF problem on IEEE 118‐bus system, the results indicate the higher accuracy of the proposed methods for recovering the joint cumulative distribution function of correlated wind samples, as well as the higher efficiency for calculating statistical information of POPF outputs. [ABSTRACT FROM AUTHOR]

This study presents a systematic analysis of Brayton batteries using Ebsilon Professional® simulations. Over 200,000 concept configurations were evaluated, with less than 1% proving physically feasible. The research aimed to assess electricity generation; coupled generation of electricity and heat; coupled generation of electricity and cooling; and coupled generation of electricity, heat, and cooling, all with or without waste heat integration. Efficiency ranged from 20% to 50% for electricity generation alone, with higher efficiencies at a compressor discharge temperature of 625 °C compared to 450 °C. Co-generation improved the overall efficiency, although at the expense of power efficiency. Notably, simultaneous electricity, heat, and cooling generation solutions were absent within the study's parameters. Lead concepts, predominantly air-based systems with or without charging line recuperators and heat exchange at various stages, were identified. These will undergo detailed dynamic system simulations, focusing on thermal energy storage. Comparison with the existing literature was limited due to differing parameters and topologies, highlighting the value of this systematic analysis in identifying optimal solutions. [ABSTRACT FROM AUTHOR]

The power sector is the single industry with the largest carbon emission in China, the carbon emission of which accounts for more than 40% of China's total carbon emissions. In relevant research on the simulation of power system operation, current studies focus more on energy conservation and economical operation, while few consider the low-carbon optimization of the power system from the perspective of carbon emissions. In addition, in relevant research on carbon reduction in the power system, current studies focus more on controlling the direct carbon emission of the source side and less on the indirect carbon emissions of the load side, which focus on the reverse effect of a user's electricity consumption behavior on the carbon reduction goals of the power system. This article delved into a deterministic simulation model of power system operation based on time series load curves and proposed a carbon reduction mechanism called the low-carbon demand response mechanism, which guides users to actively respond and reduce the carbon emission of power systems. In addition, this article conducted an empirical analysis based on the planning data of the North China Power Grid. To minimize carbon emissions, a simulation of low-carbon optimization operation for the North China Power Grid in 2040 was carried out. Then, based on the simulation results, an analysis of the carbon reduction benefits of low-carbon demand response was carried out. Ultimately, the empirical analysis verified that low-carbon optimization operation and low-carbon demand response technology possess significant carbon reduction potential for the power system. [ABSTRACT FROM AUTHOR]

With the development of lithium-ion batteries and fuel cells, the application of hybrid power systems is becoming more and more widespread. To better optimize the energy management problem of fuel cell hybrid systems, the accuracy of system modeling and simulation is very important. The hybrid system is formed by connecting the battery to the fuel cell through an active topology. Digital twin technology is applicable to the mapping of physical entities to each other with high interactivity and fast optimization iterations. In this paper, a relevant model based on mathematical logic is established by collecting actual operational data; subsequently, the accuracy of the model is verified by combining relevant operating conditions and simulating the model. Subsequently, a three-dimensional visualization model of a hybrid power system-based sightseeing vehicle and its operating environment was established using digital twin technology to improve the model simulation of the fuel cell hybrid power system. At low speeds, the simulation results of the hybrid power system-based sightseeing vehicle have a small error compared with the actual running state, and the accuracy of the data related to each internal subcomponent is high. In the simple interaction between the model display vehicle and the environment, the communication state can meet the basic requirements of the digital twin model because the amount of data to be transferred is small. This study makes a preliminary attempt at digital parallelism by combining mathematical logic with visualization models and can be used as a basis for the subsequent development of more mature digital twin models. [ABSTRACT FROM AUTHOR]

Abstract The role of cybersecurity in cyber‐physical power systems (CPPS) is reviewed, focusing on the applications of dynamic state estimation (DSE) techniques. These DSE techniques are particularly relevant with the integration of phasor measurement units (PMUs) and advanced communication infrastructure. A comprehensive review on DSE techniques and applications to efficiently protect CPPS against cyberattacks is classified into three cyber resilience phases including prevention, detection, and mitigation. The DSE techniques in the prevention phase are surveyed to improve the observability of the CPPS by the robust design of the Kalman filter and optimal protection of PMUs. The DSE techniques in the detection phase are surveyed to improve the adaptability of CPPS in various attack detection scenerios and optimise the detection accuracy. The DSE techniques in the mitigation phase are surveyed to enhance the flexibility of CPPS resource utilisation with compensation‐based, isolation‐based, and scheduling‐based strategies. Finally, the benefits and limitations of each DSE technique are summarised with potential suggestions on research directions for enhancing the cyber resilience of CPPS.

Abstract A systematic definition of an aircraft generator's “available power” (used to supply loads on its DC bus) is given, which is defined in the context of constraints on transient and steady‐state performance. Using a geometric, data‐driven approach, such a characterisation has been achieved, and a new method, called Power availablE Estimation Tool (PEET), has been developed to determine in real‐time whether a given load can be fulfilled at a given time while maintaining power quality. This is an important problem, especially for safety critical electrical systems such as more electric aircraft, for which it is imperative to know a priori whether an added load will result in voltage variations outside of allowed values. PEET is introduced and its conceptual framework is formalised. Lastly, it provides simulation results that illustrate its performance. The results show that the PEET method produces reliable a priori estimates of power availability, and that this can be achieved within time frames that make it applicable in a real‐time implementation.

Abstract This paper sets out to develop an efficient probabilistic optimal power flow (POPF) algorithm to assess the influence of wind power on power grid. Given a set of wind data at multiple sites, their marginal distributions are fitted by a newly developed generalized Johnson system, whose parameters are specified by a percentile matching method. The correlation of wind speeds is characterized by a flexible Liouville copula, which allows to model the asymmetric dependence structure. In order to improve the efficiency for solving POPF problem, a lattice sampling method is developed to generate wind samples at multiple sites, and a logistic mixture model is proposed to fit distributions of POPF outputs. Finally, case studies are performed, the generalized Johnson system is compared with Weibull distribution and the original Johnson system for fitting wind samples, Liouville copula is compared against Archimedean copula for modelling correlated wind samples, and lattice sampling method is compared with Sobol sequence and Latin hypercube sampling for solving POPF problem on IEEE 118‐bus system, the results indicate the higher accuracy of the proposed methods for recovering the joint cumulative distribution function of correlated wind samples, as well as the higher efficiency for calculating statistical information of POPF outputs.

Abstract The virtual synchronous generator (SG) (VSG) can not only enhance the inertia of the grid, but also introduce the oscillation characteristics of SG, which is easy to interact with the power angle of SG in the grid, and even produce low‐frequency oscillation (LFO). The authors first construct a two‐machine interconnected power system model containing VSG and traditional SG. The model is linearised to construct the state space equations to obtain the Phillips–Heffron model with VSG. The LFO path of action between VSG and SG is analysed. To reduce the negative damping torque provided by VSG to SG through this path, a virtual power system stabiliser (VPSS) is proposed and the controller parameters are adjusted according to the phase compensation method. Finally, the effectiveness of VPSS is verified by modal analysis and simulation comparison.

Abstract Grid integration constraints are limiting the deployment potential of renewable energy sources in Malta. Large penetrations of photovoltaics in the low voltage (LV) distribution network pose a significant risk to grid stability due to their inherent intermittency and are known to cause overvoltages and reverse power flows. The authors evaluate how self‐consumption strategies with distributed battery energy storage systems can contribute to the voltage regulation in LV networks and the reduction of reverse power flows. The batteries are controlled to absorb the reverse power flow at the dwellings' point of common coupling, before this is injected into the LV network. Simulations show that uncoordinated strategies are not suitable to address the distribution network challenges during reverse power flows and evening peak demands. On the other hand, self‐consumption coordinated by a time‐varying feed‐in tariff (FiT) can provide higher profitability to the prosumers while providing added benefits to the utility. The net‐billing profitability for the prosumers in a self‐consumption scenario with time‐varying FiT is transformed from the downward trend of the uncoordinated scenario to an upward trend against the increasing values of storage capacity.

Abstract A new technique is proposed for loss of field (LOF) detection in synchronous generators (SGs). The proposed scheme employs the variations of SG angular velocity ∆ωφ and load angle ∆δφ to reach this goal, while the mentioned parameters are estimated through air gap flux estimation. The proposed scheme performance is evaluated using realistic simulation case studies based on IEEE C. 37. 102 standard compared to the conventional impedance‐based one. The obtained results show that the presented scheme excels the conventional scheme from speed and security viewpoints. Moreover, the estimation procedure of ∆ωφ and ∆δφ is experimentally validated by using a 10 kVA SG and the results demonstrate that the proposed technique can be easily set and implemented.

Abstract The voltage‐source virtual synchronous generator is a grid‐forming type power electronic control technology and is able to support converters that have the ability of inertial, primary frequency and voltage regulation. Firstly, the authors build the small‐signal model of the voltage‐source virtual synchronous generator and conventional converters, compare and analyse the characteristics of the high‐frequency resonance modes, the results show that the voltage‐source virtual synchronous generator has almost the same high‐frequency resonance characteristics as the conventional converter. Secondly, the different control parameters and power grid strength that affect the high‐frequency resonance characteristic are analysed with eigenvalue, and the mechanism of voltage‐source VSG that caused high‐frequency resonance is derived. The leading factor that causes high‐frequency resonance is power grid strengths, and the authors proposed introducing virtual impedance into the front‐end channel of the current inner loop control strategy to suppress resonance for the voltage‐source virtual synchronous generator based on the theoretical analysis with the small‐signal model and eigenvalue analysis. In addition, the electromagnetic transient simulation model and RT‐LAB controller‐in‐loop platform are built, and the simulation and experiment results indicate the effectiveness of the virtual impedance control strategy.

At present, there is a global rise in electricity consumption, leading to an accelerated depletion of natural resources due to the reliance on fossil fuels to fulfill this energy demand. Consequently, there exists a worldwide emphasis on enhancing the proportion of renewable energy sources in electricity generation. Biomass, as a renewable energy source, presents a viable alternative to certain fossil energy sources for combustion in electricity generation. This study focuses on a 660 MW coal-fired power plant as the subject of investigation, employing Aspen Plus simulation software (V11) to replicate the operational dynamics of the plant. A model of the direct mixed combustion biomass system within the coal-fired boiler is constructed, and its accuracy is validated against operational data obtained from the power plant. Moreover, a model elucidating the direct co-combustion of biomass in a coal-fired boiler, augmented by flue gas recirculation, was developed through the integration of biomass pre-treatment and flue gas recirculation technologies. This study explores the impacts of varying biomass blending ratios and flue gas recirculation on parameters, including flue gas volume, power generation efficiency, boiler performance, water vapor content, and emissions of pollutants. These findings indicate an inverse relationship between the mixing ratio and various performance metrics as follows: power generation, boiler efficiency, as well as NOX and SO2 content, with larger mixing ratios resulting in diminished values. Furthermore, the incorporation of flue gas recirculation was observed to mitigate furnace temperatures and suppress NOX emissions. [ABSTRACT FROM AUTHOR]

Power system simulation is vital for designing and evaluating the performance of electrical system protection and control devices. Although several commercial simulators exist, most are expensive and not open-source code. It is essential to develop educational and research simulators that can prepare students, allow researchers to develop new methodologies, and assist system operators in making decisions. This paper aims to present a computer simulation platform called AnaDyn (dynamic analysis), a non-commercial and open-source platform. AnaDyn is an educational/research platform that allows dynamic (transient stability), quasi-steady-state simulation, modal, and power flow analysis. Short- and long-term studies of voltage, frequency, and rotor angle instability problems can be performed. The main characteristics of AnaDyn are quasi-steady-state simulation, in which the equations are not simplified; easy integration with other tools and toolboxes, since AnaDyn is developing in MATLAB; flexible modeling that allows the inclusion of new devices and controller tests. The detailed modeling of various power system devices, the description of the numerical solution method, and the interface are also presented in this work. The platform is validated by comparing a test system's results with those obtained with Brazil's most popular commercial software. The main potentials of quasi-steady-state simulation are also presented. The results indicate that AnaDyn is efficient for educational and research studies on the stability of short- and long-term electrical systems. [ABSTRACT FROM AUTHOR]

Inter-area power oscillations, a condition where a group of generators in different areas oscillate against each other, are becoming hard to control due to the recent complexity of power systems. This paper aims to enhance the stability of the modified Kundur two-area-four-machine network model, focusing on the implementation of a robust secondary controller on line commutated converter based multi-terminal high voltage direct current systems. This effort is to provide a better sustainable means of power transmission. The proposed solution entails integrating a local generator controller and a robust controller specifically designed to further mitigate inter-area power oscillations. This study conducted three operational scenarios: the local generator controller with double circuits alternating current lines, the local generator controller with multi-terminal direct current system controllers, and the local generator controller with direct current controllers and a secondary controller. Simulation results, executed using electromagnetic transient simulation engine on power systems computer aided design, demonstrated notable improvement in damping inter-area power oscillations with the incorporation of multi-terminal direct current system. A substantial enhancement of 100% in dampening inter-area power oscillations was observed upon implementing a secondary controller on the multi-terminal direct current system. [ABSTRACT FROM AUTHOR]

Medium-voltage DC (MVDC) technology has gained increasing attention in recent years. Power electronics devices dominate these grids. Accurate simulation of such a grid, with detailed models of switching semiconductors, can quickly became very time-consuming, according to the number of connected devices to be simulated. A simulation approach based on interactions on a continuous time model can be very interesting, especially for developing a system-level control model of such a modern MVDC distribution grid. The aim of this paper is to present all the steps required for obtaining a continuous time modelling of a +/−10 kV MVDC grid case study, including a solid-state transformer (SST)- and modular multilevel converter (MMC)-based active front end (AFE). An additional aim of this paper is to supply educational content about the use of the continuous time simulation approach, thanks to a detailed description of the various devices modelled into the presented MVDC grid. The results of a certain number of simulation scenarios are eventually presented. [ABSTRACT FROM AUTHOR]

Over the last decade considerable efforts have been made to reduce greenhouse gas emissions, leading to the significant development and implementation of renewable energy plants across all power systems in the world. Wind energy has consolidated its position as one of the two key energy sources (in conjunction with solar photovoltaics) to achieve completely green power systems. Integrating wind energy into power systems is a more complicated task compared to traditional generation systems, as wind energy relies on a variable energy source characterised by high variability. Several tools currently exist to simulate the effect of wind energy generation in power systems, but they often lack the versatility demanded by researchers. This paper analyses how both Python 3.11 and DIgSILENT PowerFactory 2024 can be used synergistically to assess the implementation of wind power plants, highlighting how the use of these two tools combined can be of great interest for both researchers and grid operators. [ABSTRACT FROM AUTHOR]

The integration of renewable energy sources into power systems has increased significantly in recent years. Among various types of renewable energy, the use of wind energy is growing rapidly due to its low operating cost, wide distribution worldwide, and no greenhouse gas emissions. However, power systems integrated with wind energy may face stability and reliability issues due to the intermittent nature of wind power. Therefore, in power systems connected to wind farms, it is usually required to use some compensators such as static synchronous series compensator (SSSC) to increase the system performance under abnormal conditions. On the other hand, for an SSSC to be effective in improving the system performance, it must be equipped with a suitable controller. In this paper, a fuzzy logic controller (FLC) is used for the SSSC because of its advantages over conventional controllers. Extensive research has been conducted in power systems with wind turbines in which SSSC or FLC has been used; however, their simultaneous application in such systems has received less attention. Therefore, this article aims to fill this gap. The proposed method is implemented on two power systems and the simulation results are analyzed. In both systems, the dynamic behavior of three different wind farms is examined. In the first and second wind farms, either a squirrel cage induction generator (SCIG) or doubly-fed induction generator (DFIG) are used, whereas in the third one which is a combined wind farm (CWF), an equal number of SCIG and DFIG are employed. In wind farms with SCIG or DFIG, an SSSC is also utilized. Furthermore, an FLC is employed for the SSSC to improve its efficacy. A proportional integral (PI) controller is also considered for the SSSC, and its results are compared with FLC results. The simulation results confirm the superiority of FLC over PI controller. [ABSTRACT FROM AUTHOR]

Constraining the virtual inertia of variable-speed wind turbines within the variable frequency limit time will be the key to improving the wind power's reliability in actively supporting the system frequency. First, this paper analyzes the controllable characteristics and evaluation methods of the virtual inertia of the wind turbine. Second, it quantifies the variable frequency limit time of the grid with high-proportion wind power and considers the wind turbine speed and power margin to restrict the virtual inertia of the wind turbine during the period of frequency drop or increase to provide reliable inertia support to ensure the safety of the system frequency. On this basis, the inertia demand under the frequency safety of the system was analyzed, and the virtual inertia control strategy of the variable-speed wind turbine in the variable frequency limit time was proposed using the speed tracking performance of the wind turbine. Finally, the grid with a high-proportion wind power simulation system is built to verify that the variable- speed wind turbine can reliably satisfy the inertia demand of system frequency modulation under the proposed control strategy and significantly improve its active support performance to the power grid. [ABSTRACT FROM AUTHOR]

This paper introduces a novel and improved double-resistor damped double-tuned passive power filter (DR-DDTF), designed using multi-objective optimization algorithms to mitigate harmonics and increase the hosting capacity of distribution systems with distributed energy resources. Although four different topologies of single-resistor damped double-tuned filters (DDTFs) have been studied before in the literature, the effectiveness of two different DR-DDTF configurations has not been examined. This work redresses this gap by demonstrating that via comprehensive simulations on two power systems, DR-DDTF provides better harmonic suppression and resonance mitigation than single-resistor alternatives. When it comes to optimizing the DR-DDTF for maximum hosting capacity and minimum system active power losses, the multi-objective artificial hummingbird outperformed six other algorithms in the benchmark. To allow for higher penetration of distributed generation without requiring grid upgrades, this newly developed harmonic mitigation filter provides a good alternative. [ABSTRACT FROM AUTHOR]

The voltage‐source virtual synchronous generator is a grid‐forming type power electronic control technology and is able to support converters that have the ability of inertial, primary frequency and voltage regulation. Firstly, the authors build the small‐signal model of the voltage‐source virtual synchronous generator and conventional converters, compare and analyse the characteristics of the high‐frequency resonance modes, the results show that the voltage‐source virtual synchronous generator has almost the same high‐frequency resonance characteristics as the conventional converter. Secondly, the different control parameters and power grid strength that affect the high‐frequency resonance characteristic are analysed with eigenvalue, and the mechanism of voltage‐source VSG that caused high‐frequency resonance is derived. The leading factor that causes high‐frequency resonance is power grid strengths, and the authors proposed introducing virtual impedance into the front‐end channel of the current inner loop control strategy to suppress resonance for the voltage‐source virtual synchronous generator based on the theoretical analysis with the small‐signal model and eigenvalue analysis. In addition, the electromagnetic transient simulation model and RT‐LAB controller‐in‐loop platform are built, and the simulation and experiment results indicate the effectiveness of the virtual impedance control strategy. [ABSTRACT FROM AUTHOR]

A new technique is proposed for loss of field (LOF) detection in synchronous generators (SGs). The proposed scheme employs the variations of SG angular velocity ∆ωφ and load angle ∆δφ to reach this goal, while the mentioned parameters are estimated through air gap flux estimation. The proposed scheme performance is evaluated using realistic simulation case studies based on IEEE C. 37. 102 standard compared to the conventional impedance‐based one. The obtained results show that the presented scheme excels the conventional scheme from speed and security viewpoints. Moreover, the estimation procedure of ∆ωφ and ∆δφ is experimentally validated by using a 10 kVA SG and the results demonstrate that the proposed technique can be easily set and implemented. [ABSTRACT FROM AUTHOR]

With the escalating challenges of climate change and the imperative for carbon neutrality, evaluating the carbon footprint of regional power systems becomes crucial. To address this issue, a low-carbon evaluation framework for regional power systems is developed. First, this study identifies the fundamental requirements that the index system for the low-carbon power system should follow and specifies the general direction for the index system's creation. Second, an evaluation model for carbon reduction ability is proposed by considering generation side, grid side and load side of the power system. Then, a comparative evaluation model for the carbon reduction capability of multi-regional power systems is proposed to spatiotemporally compare the carbon reduction capability of different power systems. Next, a quantification method for the weights of low-carbon evaluation indicators is established based on the power system simulation of multi-scenario scheduling and index sensitivity analysis method. Finally, a low-carbon comprehensive score for regional power systems is created by combining the evaluation results of the system's carbon reduction capacity with index weights. The practical research results in a region of Zhejiang province in China demonstrate that the proposed model can provide a reasonable and feasible evaluation plan for the low-carbon construction of regional power systems. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of designing an observer-based event-triggered H ∞ controller for a Hamiltonian system with delays incorporated in the underlying network. As our contributions, we first propose an event-triggered scheme which uses the Hamiltonian to decide whether to trigger the event generator at the sampling time. Additionally, when states are not exactly known globally asymptotically stable, we proceed to design an observer-based controller with which the resulting closed-loop system can be transformed into a time-delay Hamiltonian system. Based on the structural characteristic of the Hamiltonian systems, sufficient conditions are given to guarantee the closed-loop system to achieve the H ∞ performance index with external disturbances in available and unavailable states, respectively. Finally, multi-machine power systems as simulation examples are illustrated to validate our proposed results. • Event-triggered H ∞ control is discussed via a Hamiltonian approach. • A discrete event-triggered scheme is proposed for saving communication resources. • An observer is designed for networked Hamiltonian systems with unknown states. • The influence of network-induced delay is considered. [ABSTRACT FROM AUTHOR]

In this paper we present a scalable approach based on the latency-based linear multistep compound method to use graphic processing unit (GPU) to accelerate the power system simulations with electromagnetic transients.To balance between the computational load and accuracy, we modeled the power system using shifted frequency analysis. Then, to efficiently exploit the hardware, our computational approach is designed to utilize both data-parallel and task-parallel execution. In addition, a graph-based thread safety design is introduced to achieve high scalability in the paralleled component computations. Furthermore, our implementation introduces a translation layer for different heterogeneous computing frameworks during compile time, so that a wide range of GPU devices can be supported without losing performance. Finally, benchmark results show that our approach achieves faster-than-real-time capability for systems with hundreds to thousands of nodes.

Abstract Although there are many methods to improve the fault ride‐through (FRT) capability of doubly‐fed induction generator (DFIG) systems at present, each method has its shortcomings, especially the applicability under different voltage dips (VDs), so an improved system structure with a dynamic switching topology and a corresponding control scheme is proposed. Based on the mechanism analysis that the series impedance of the stator can effectively reduce the overcurrent on the rotor side, and considering the feasibility of the FRT scheme in engineering, the dynamic switching topology is designed. The selection of theoretical parameters in different cases is also analysed and designed. Simultaneously, to cooperate with the hardware measures, the control scheme of the rotor side converter (RSC) under different conditions is also improved. The RSC can use the control scheme of active flux attenuation to effectively and quickly reduce the overcurrent on the rotor side, and use reactive power support to accelerate the voltage recovery. The novelty of the FRT scheme is that the scheme can dynamically adjust the topology structure and control scheme under different voltage dips. Thus, its ride‐through performance during fault is better under different conditions. A simulation model of the improved system structure and control scheme is built on the MATLAB/Simulink platform. Through the comparison of simulation data, the validity and correctness of the proposed FRT scheme are verified.

Abstract A Cyber‐Physical System (CPS) is a spatiotemporal multi‐dimensional and heterogeneous hybrid autonomous system composed of deep integration of information resources and physical systems. With the development of digitisation and digitalisation, a large number of data acquisition equipment, computing equipment, and electrical equipment are interconnected between the power grid and the information communication network. The power grid has thus been restructured as a mature and highly complex CPS. In order to promote the development of power grid CPS technologies and provide a reference for relevant researchers in the field, the origin and concept of CPS and features in power grid CPS are introduced firstly. Then the key technologies of power grid CPS simulation are discussed and further analysed from three perspectives, including modelling theory, simulation methods, and system‐level simulation. On this basis, the application of CPS simulation technology in future power grids has been prospected.

The recent transformation of the energy sector brings new challenges in areas such as supply security, efficiency, and reliability. Especially the increase of decentralized power plants leads to a more complex energy system and an increasing complexity. This requires expansion and digitization of the power grid as well as an initiative-taking operation of the grid operator. To investigate such complex systems and its phenomena, modern development methods such as real-time simulation or digital twins (DT) can be used. In this approach a digital replica of the real-world system, a grid section, is developed, which can represent or predict the behavior of the real distribution grid. For this, a model of the real-world system is derived and implemented in a co-simulation environment, in which it receives data via an analyzer or measurement system from the grid model. This paper focuses on the development of the digital twin of a testing grid and a grid analyzer for the measurement. With the digital twin of the testing grid, a first approach is achieved in a real-time capable environment showing the functionalities and interactions of a digital twin. Subsequently the development of the digital twin model is explained, and the results are discussed.

This research addresses a significant gap in power system protection methodologies by developing a dedicated simulation environment that supports the communication of protection relays via the IEC 61850 protocol. Current studies have focused on hardware-in-the-loop approaches, but there is a lack of research in the software-in-the-loop domain. This limitation means that manufacturer-independent simulations cannot be performed, restricting testing to the capabilities provided by the manufacturer. By introducing a relay capable of communicating within a Simulink-modeled power system through socket programming, this study harnesses the capabilities of the IEC 61850 GOOSE protocol and sampled values. This work aims to eliminate the manufacturer dependencies present in hardware-in-the-loop approaches, thereby enabling the independent development of new protection and control strategies in an academic context. Furthermore, by facilitating advanced communication strategies through a detailed simulation framework, this research contributes to the broader field of electrical engineering by offering a robust tool for developing, testing, and validating new relay communication techniques and protection schemes. This approach not only fills a critical gap in simulation capabilities but also paves the way for future advancements in power system protection and management regarding the IEC 61850 protocol.

As both the generation resources and load types have changed and grown over the past few decades, there is a growing need for analysis that spans traditional simulation boundaries; for example, evaluating the impact of distribution-level assets (e.g. rooftop solar, EV chargers) on bulk-power system operation. Co-simulation is a technique that allows simulators to trade information during run-time, effectively creating larger and more complex models. HELICS is a co-simulation platform that has been developed to enable these kinds of power system analysis, incorporating tools from a variety of domains including the electrical power grid, natural gas, transportation, and communications. This paper summarizes the technical design of HELICS, describes how tools can be integrated into the platform, and reviews a number of analyses that have been performed using HELICS. A short video summary of this paper can be found at https://youtu.be/BIUiR_K87Wc.

The large-scale offshore wind power integrated into the onshore power grid through voltage source converter-based high voltage direct current (VSC-HVDC) system is unable to provide inertia response and frequency support to the onshore power grid. To improve the frequency characteristics of the receiving-end power grid, a coordinated frequency control strategy combining VSC-HVDC and offshore wind power is proposed. The onshore converter adopts virtual inertia control, which uses DC capacitors to absorb or release energy for inertia support after the receiving-end grid is disturbed. Wind-farm-side VSC (WFVSC) obtains the frequency signal of the receiving-end power grid by detecting the local DC voltage. The offshore wind farm (OWF) transfers the frequency deviation into an additional power signal and sends it to the power controller to adjust the output, thereby performing inertia and primary frequency response. In addition, a secondary frequency regulation strategy for wind farms has been designed to achieve non-difference frequency regulation of the receiving-end power grid. Finally, a simulation model of VSC-HVDC integrated OWF system is constructed to demonstrate the proposed coordinated frequency control strategy for VSC-HVDC and OWF. The results indicate that the proposed control strategy can effectively enhance the frequency support capability of the receiving-end power grid. [ABSTRACT FROM AUTHOR]

In order to achieve the Paris climate targets, the German government has developed phased plans and anchored these in an amendment to the Renewable Energy Sources Act (EEG). This not only defines expansion targets for renewable energy producers, but also the additional amounts of energy that must be available in the electricity grid in future if it is to supply the mobility and building heating sectors, which are currently still powered by fossil fuels. While the lack of grid transport capacities is recognized and discussed in the public debate, another known and critical hurdle is rarely presented here. This is the temporal distribution of power from renewable energies and its effects on the processes involved in controlling the grid balance. By analyzing a target scenario specified in the EEG for 2030 and another for 2040+, which a German economic research institute recommends to policymakers, the aim is to investigate whether their targets can be achieved under the conditions of the natural fluctuations occurring in Germany and the quantities of renewable energy that can be harvested with a reasonable use of resources. The focus is on simulating future generation curves using historical data in such a way that they show the typical weather-driven behaviour to be expected in Germany. Unavoidable Surplus generation is used as efficiently as possible with electricity and hydrogen storage systems. Both scenarios fall considerably short of their targets. CO2-free coverage of the demand specified for the long-term future is only possible with a quantity of generators that is at the limit of what is feasible. The reason for this is that the current plans are obviously based on an unrealistic picture of the temporal distribution of renewable energy output. Achieving the transformation goals in Germany could be much more complex than politicians currently believe and may require a change in strategy sooner or later. [ABSTRACT FROM AUTHOR]

To address China's small coal power units facing shutdown and retirement, which urgently need life cycle extension and renovation, a complete solar thermal storage simulation power generation system based on the original site of a decommissioned thermal power unit is developed using Ebsilon software in this study. The operational characteristics of the simulated system are studied in depth to build a system with integrity and stability that can carry out economic and stable power production. The results of simulation tests on the solar collector system and the thermal storage subsystem show that the energy storage rate of the energy storage subsystem is affected by light intensity and significantly increases at approximately 8:00 a.m. The annual power generation capacity of the system is influenced by the energy storage hours set by the energy storage subsystem, and the annual power generation capacity increases more significantly when the energy storage hours are controlled within the range of 5–8 h. The operating efficiency of the corresponding subsystem can be improved by selecting a suitable location for the light intensity required and controlling the effective reflectivity of the mirror field and the energy storage hours, which can ensure the system's stable operation. The research results provide theoretical guidance for reusing and transforming retired thermal power units. [ABSTRACT FROM AUTHOR]

Aiming to solve the problems of insufficient dynamic responses, the large loss of energy storage life of a single power cell, and the large fluctuation in DC (direct current) bus voltage in fuel cell vessels, this study takes a certain type of fuel cell ferry as the research object and proposes an improved equivalent minimum hydrogen consumption energy management strategy, based on fuzzy logic control. First, a hybrid power system including a fuel cell, a lithium–iron–phosphate battery, and a supercapacitor is proposed, with the simulation of the power system of the modified mother ship. Second, a power system simulation model and a double-closed-loop PI (proportion integration) control model are established in MATLAB/Simulink to design the equivalent hydrogen consumption model and fuzzy logic control strategy. The simulation results show that, under the premise of meeting the load requirements, the control strategy designed in this paper improves the Li-ion battery's power, the Li-ion battery's SOC (state of charge), the bus voltage stability, and the equivalent hydrogen consumption significantly, compared with those before optimization, which improves the stability and economy of the power system and has certain practical engineering value. [ABSTRACT FROM AUTHOR]

This paper investigates the observer-based adaptive fuzzy quantized control problem for a class of fractional-order nonlinear time-delay systems with unknown control gains based on a modified fractional-order dynamic surface control (FODSC) technique and an indirect Lyapunov method. First, a fractional-order, high-gain state observer is constructed to estimate unavailable state information. Furthermore, the Nussbaum gain technique and a fractional-order filter are adopted to cope with the problem of unknown control gains and to reduce the computational complexity of the conventional recursive procedure, respectively. Moreover, through integration with the compensation mechanism and estimation model, the adaptive fuzzy quantized controllers and adaptive laws are designed to ensure that all the signals of the closed-loop system are bounded. In the end, the proposed controller is applied to a numerical example and a single-machine-infinite bus (SMIB) power system; the simulation results show the validity, superiority, and application potential of the developed control strategy. [ABSTRACT FROM AUTHOR]

Optimal power flow (OPF) analysis enables the in-depth study and examination of islanded microgrid design and operation. The development of the analysis framework, including modeling, formulating, and selecting effective OPF solvers, however, is a nontrivial task. As a result, this paper presents a tutorial on an OPF modeling framework, offering a mathematical model that can be readily implemented using established open-source software tools such as OpenDSS, Pyomo, and IPOPT. The framework is versatile, capable of representing single-phase and unbalanced three-phase islanded microgrids. Various inverter models, such as those of grid forming and following equipped with their operating characteristics, can be incorporated. The efficacy of the proposed framework is demonstrated in studying the OPF of single-phase and three-phase microgrids. [ABSTRACT FROM AUTHOR]

Among the skills to be developed in the study of reactive power compensation control devices in electrical power systems is the analysis of the control models of static reactive compensators. Python is free software that allows data analysis, control and simulation of electrical power systems. The objective of the article is to propose an application that allows the study of reactive power compensation that helps improve the teaching-learning process of the subject of Power Electronics. The study was based on a qualitative - descriptive methodology in which analytical - synthetic and inductive - deductive methods were used and the survey was used as empirical methods. For the processing and analysis of the information collected, the calculation of absolute and relative frequencies was used as a statistical method. The results corroborate the importance of using the proposed method to improve the teaching-learning process. [ABSTRACT FROM AUTHOR]

Abstract A novel method is introduced to determine cost‐optimized active power curtailment (APC) of renewable energy sources (RES) considering weather‐dependent dynamic line rating (DLR). A new formulation of the security‐constrained optimal power flow (SC‐OPF) is developed and applied in a case study. The reduction of the required preventive APC in the (N-0) case for (N-1) secure grid operation due to the consideration of thermal inertia of overhead power lines is demonstrated. Considering thermal inertia allows relying on curative APC that is activated only after an (N-1) situation occurs. The overhead power line temperature, calculated with the temperature‐dependent power flow (TDPF), acts as a new limit for line loading and releases unused transmission reserves. The TDPF algorithm is integrated in the open‐source Python library pandapower, providing access to it to the broader community. The power system can be utilized to a greater extent, with a reduced demand for congestion management.

Abstract In this paper, the problem of harmonic coupling between the converter transformer and the converter under the action of geomagnetically induced current (GIC) is proposed to be investigated. Firstly, a model of a 12‐pulse line commutated converter high voltage direct current (LCC‐HVDC) converter station based on harmonic state space (HSS) theory is established. Secondly, the harmonic components of the interaction between the AC‐side harmonic current and the DC‐side harmonic voltage are qualitatively analyzed by using the harmonic modulation theory. Through the simulation model and harmonic state space (HSS) calculation model, the harmonic coupling characteristics of power grid are analyzed. Finally, the harmonic current and voltage amplitude of AC / DC power grid under different GIC are calculated, and the characteristics and rules of AC / DC harmonic propagation are revealed. Among them, the amplitude of the 2nd harmonic current on the AC side and the 3rd harmonic current on the DC side increases linearly with the GIC. In addition, the 3rd and 9th harmonics on the AC side are also greatly affected by the magnetic bias of the converter.

The integration of new battery technologies has become a focal point for distribution utilities, driven by decreasing costs and the need for fast responsiveness. Transportable battery energy storage systems (TBESSs) offer additional flexibility, allowing connection at multiple substations or grid feed points. However, concerns remain regarding their impact on distribution systems (DSs), particularly on protection devices (PDs). This study addresses these concerns by investigating the influence of TBESSs on the protection systems of a real-world distribution network. Given the lack of studies in the current literature on this topic, this research aims to fill this gap by examining the potential effects of TBESS integration on PDs, such as reclosers and fuses, within a DS. Utilizing a model based on real data from a Brazilian utility, we conducted simulations to analyze the effects of TBESSs in both charging and discharging modes on the protection systems of three feeders. The methodology involved assessing variations in the operation times and coordination of PDs to determine if TBESS integration would necessitate adjustments to existing protection configurations. The results demonstrated that TBESS integration resulted in only minor variations in PD operating times, typically within hundredths of a second, indicating a negligible impact on protection performance. Consequently, no significant modifications to the protection system are required to accommodate TBESSs. These findings suggest that TBESSs can be seamlessly integrated into existing distribution networks, maintaining system reliability and operational integrity. This study provides valuable insights and a robust procedure for utilities to analyze the integration of TBESSs, supporting the effective deployment of modern energy storage solutions in DSs.

The deployment of Electrically Trace Heated Pipe-in-Pipe (ETH-PiP) brings the challenges of reliable protection selection and setting. This paper presents a study of relays and protection function optimization for ETH-PiP systems. The study is based on the developed simulation model of a typical ETH-PiP system. The paper presents simulation studies of physical phenomena occurring during electrical disturbances in the ETH-PiP system and offers detailed analyses applicable to system protection, including detection of disturbances, location, and elimination.

This paper examines the use of manifold learning in the context of electric power system transient stability analysis. Since wide-area monitoring systems (WAMSs) introduced a big data paradigm into the power system operation, manifold learning can be seen as a means of condensing these high-dimensional data into an appropriate low-dimensional representation (i.e., embedding) which preserves as much information as possible. In this paper, we consider several embedding methods (principal component analysis (PCA) and its variants, singular value decomposition, isomap and spectral embedding, locally linear embedding (LLE) and its variants, multidimensional scaling (MDS), and others) and apply them to the dataset derived from the IEEE New England 39-bus power system transient simulations. We found that PCA with a radial basis function kernel is well suited to this type of power system data (where features are instances of three-phase phasor values). We also found that the LLE (including its variants) did not produce a good embedding with this particular kind of data. Furthermore, we found that a support vector machine, trained on top of the embedding produced by several different methods was able to detect power system disturbances from WAMS data. [ABSTRACT FROM AUTHOR]

A novel method is introduced to determine cost‐optimized active power curtailment (APC) of renewable energy sources (RES) considering weather‐dependent dynamic line rating (DLR). A new formulation of the security‐constrained optimal power flow (SC‐OPF) is developed and applied in a case study. The reduction of the required preventive APC in the (N-0)$(N\text{-}0)$ case for (N-1)$(N\text{-}1)$ secure grid operation due to the consideration of thermal inertia of overhead power lines is demonstrated. Considering thermal inertia allows relying on curative APC that is activated only after an (N-1)$(N\text{-}1)$ situation occurs. The overhead power line temperature, calculated with the temperature‐dependent power flow (TDPF), acts as a new limit for line loading and releases unused transmission reserves. The TDPF algorithm is integrated in the open‐source Python library pandapower, providing access to it to the broader community. The power system can be utilized to a greater extent, with a reduced demand for congestion management. [ABSTRACT FROM AUTHOR]

Various methods are used to produce electrical energy, each of which has its own advantages and disadvantages. The power plant is one of the important parts of the power system, which is responsible for the proper production of electrical energy. In this study, the dynamic behavior of load frequency control is compared and analyzed for three power systems, each including a steam power plant, a hydro power plant, and a gas power plant. The state equations of each system are separately expressed, and then using the analysis of eigenvalues (system modes), the dynamic behavior of the power system is shown for changes in the consumption load. The power system model is simulated in MATLAB software showing the correctness of the analysis of eigenvalues. In addition, the power system model in Simulink MATLAB for each power plant is separately designed and the correctness of the results is shown. The frequency response of the transfer function, i.e., frequency changes to load demand changes, is shown in each production unit. The results of simulation and examination of the power system modes reveal that the steady state response of the three production units is similar to step changes in load demand, and only the speed of reaching the steady state will be different in them. [ABSTRACT FROM AUTHOR]